Pediatrics_Nelson

Pediatrics_Nelson. Increased flow across valve (ASD, PAPVR) Prolonged flow across valve (pulmonary stenosis) Electrical delay (right bundle branch block) Early aortic closure (severe mitral regurgitation) Increased in pulmonary hypertension Decreased in severe pulmonary stenosis, tetralogy of Fallot ASD, Atrial septal defect; d-TGA, dextro-transposition of the great arteries; l-TGA, levo-transposition of the great arteries; PAPVR, partial anomalous pulmonary venous return. Murmurs should be classified as systolic, diastolic, or continuous. Most murmurs are systolic and can be divided further into systolic ejection murmurs or holosystolic (also called pansystolic or regurgitant) murmurs. Ejection murmurs are crescendo-decrescendo with a short time between S1 and the onset of the murmur (isovolumic contraction). Systolic ejection murmurs require the ejection of blood from the ventricle and may occur with aortic stenosis, pulmonary stenosis, atrial


Pediatrics_Nelson

Pediatrics_Nelson. Grade I Very soft, heard in quiet room with cooperative patient Grade IV Loud with palpable thrill Grade V Loud with thrill, audible with stethoscope at 45° angle Grade VI Loud with thrill, audible with stethoscope off chest 1 cm septal defects (ASDs), and coarctation of the aorta. Holosystolic murmurs have their onset with S1. The murmur has a plateau quality and may be heard with ventricular septal defects (VSDs) and mitral or tricuspid regurgitation. A late regurgitant murmur may be heard after a midsystolic click in mitral valve prolapse.


Pediatrics_Nelson

Pediatrics_Nelson. Murmurs are often heard along the path of blood flow. Ejection murmurs usually are best heard at the base of the heart, whereas holosystolic murmurs are louder at the LLSB and apex. Pulmonary ejection murmurs radiate to the back and axilla. Aortic ejection murmurs radiate to the neck. The intensity or loudness of a heart murmur is assessed as grade I through VI (Table 139-4). The frequency or pitch of a murmur provides information regarding the pressure gradient. The higher the pressure gradient across a narrowed area (valve, vessel, or defect), the faster the flow and higher the frequency of the murmur. Low-frequency murmurs imply low pressure gradients and mild obstruction or less restriction to flow. vibratory murmur LLSB or between LLSB and apex Grades I-III/VI Vibratory, musical quality Intensity decreases in upright position


Pediatrics_Nelson

Pediatrics_Nelson. vibratory murmur LLSB or between LLSB and apex Grades I-III/VI Vibratory, musical quality Intensity decreases in upright position Venous hum Continuous murmur 3–6 yr Infraclavicular region (right > left) Grades I-III/VI Louder with patient in upright position Changes with compression of jugular vein or turning head Carotid bruit Systolic ejection murmur Any age Neck, over carotid artery Grade I-III/VI ejection murmur LUSB Grade I-III/VI Usually softer in upright position Does not radiate to back Peripheral Systolic ejection murmur Newborn to 6 mo pulmonary Axilla and back, LUSB/ stenosis RUSB Grade I-III/VI Harsh, short, high-frequency LLSB, Left lower scapular border; LUSB, left upper scapular border; RUSB, right upper scapular border.


Pediatrics_Nelson

Pediatrics_Nelson. Grade I-III/VI Harsh, short, high-frequency LLSB, Left lower scapular border; LUSB, left upper scapular border; RUSB, right upper scapular border. Diastolic murmurs are much less common than systolic murmurs, and should be considered abnormal. Early diastolic murmurs occur when there is regurgitation through the aortic or pulmonary valve. Mid-diastolic murmurs are caused by increased flow (ASD, VSD) or anatomic stenosis across the mitral or tricuspid valves. Continuous murmurs are heard when there is flow through the entire cardiac cycle and are abnormal with one common exception, the venous hum. A PDA is the most common abnormal continuous murmur. Continuous murmurs can also be heard with coarctation of the aorta when collateral vessels are present.


Pediatrics_Nelson

Pediatrics_Nelson. Normal physiologic or innocent murmurs are common, occurring in at least 80% of normal infants and children, heard most often during the first 6 months of life, from 3 to 6 years of age, and in early adolescence. They have also been called benign, functional, vibratory, and flow murmurs. Characteristic findings of innocent murmurs include the quality of the sound, lack of significant radiation, and significant alteration in the intensity of the murmur with positional changes (Table 139-5). Most important, the cardiovascular history and examination are otherwise normal. The presence of symptoms, including failure to thrive or dysmorphic features, should make one more cautious about diagnosing a normal murmur. Diastolic, holosystolic, late systolic, and continuous (except for the venous hum) murmurs and the presence of a thrill are not normal.


Pediatrics_Nelson

Pediatrics_Nelson. Mild desaturation that is not clinically apparent may be the onlyearly finding in complex congenital heart defects. Comparingpulse oximetry between the right arm and a lower extremity mayallow diagnosis of a ductal dependent lesion in which desaturatedblood flows right to left across a PDA to perfuse the lower body.This is now becoming a routine screening test in newborn infantsto rule out congenital heart disease. The 12-lead electrocardiogram (ECG) provides information about the rate, rhythm, depolarization, and repolarizationof the cardiac cells and the size and wall thickness of the chambers. It should be assessed for rate, rhythm, axis (P wave, QRS, and T wave), intervals (PR, QRS, QTc) (Fig. 139-2), and voltages (left atrial, right atrial, left ventricular, right ventricular) adjusted for the child’s age.


Pediatrics_Nelson

Pediatrics_Nelson. The P wave represents atrial depolarization. A criterion for right atrial enlargement is an increase of the amplitude of the P wave, reflected best in lead II. The diagnosis of left atrial enlargement is made by prolongation of the second portion of the P wave, exhibited best in the chest leads. The PR interval, measured from the beginning of the P wave to the beginning of the QRS complex, increases with age. Conduction time is shortened when the conduction velocity is increased (glycogen storage disease) or when the atrioventricular node is bypassed (Wolff-Parkinson-White syndrome). A prolonged PR interval usually indicates slow conduction through the atrioventricular node. Diseases in the atrial myocardium, bundle of His, or Purkinje system may also contribute to prolonged PR intervals.


Pediatrics_Nelson

Pediatrics_Nelson. The QRS complex represents ventricular depolarization. A greater ventricular volume or mass causes a greater magnitude of the complex. The proximity of the right ventricle to the chest surface accentuates that ventricle’s contribution to the complex. Changes in the normal ECG occur with age. Normative data for each age group must be known to make a diagnosis from the ECG. The QT interval is measured from the beginning of the QRS complex to the end of the T wave. The corrected QT interval (corrected for rate) should be less than 0.45 second (QTc = QT/ precedingR to R interval). The interval may be prolonged in children with hypocalcemia or severe hypokalemia. It is also prolonged in a group of children at risk for severe ventricular arrhythmias and sudden death (prolonged QT syndrome). Drugs such as quinidine and erythromycin may prolong the QT interval.


Pediatrics_Nelson

Pediatrics_Nelson. A systematic approach to reading a chest radiograph includes assessment of extracardiac structures, the shape and size of the heart, and the size and position of the pulmonary artery and aorta (Fig. 139-3). Assessment of the location and size of the heart and cardiac silhouette may suggest a cardiac defect. On a good inspiratory film, the cardiothoracic ratio should be Figure 139-2 Nomenclature of electrocardiogram (ECG) waves and intervals.


Pediatrics_Nelson

Pediatrics_Nelson. SVCAoPARARVLVLAABFigure 139-3 A, Parts of the heart whose outlines can be identified on a routine chest x-ray. B, Routine posteroanterior x-ray of the normal cardiac silhouette. Ao, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; SVC, superior vena cava. (From Andreoli TE, Carpenter CCJ, Plum F, et al, editors: Cecil Essentials of Medicine, ed 2, Philadelphia, 1990, WB Saunders.) less than 55% in infants under 1 year of age and less than 50% in older children and adolescents. An enlarged heart may be due to an increased volume load (left-right shunt) or due to myocardial dysfunction (dilated cardiomyopathy). The shape of the heart may suggest specific congenital heart defects. The most common examples are the boot-shaped heart seen with tetralogy of Fallot, the egg-on-a-string seen with dextroposed transposition of the great arteries, and the “snowman” seen with supracardiac total anomalous pulmonary venous return. The chest


Pediatrics_Nelson

Pediatrics_Nelson. with tetralogy of Fallot, the egg-on-a-string seen with dextroposed transposition of the great arteries, and the “snowman” seen with supracardiac total anomalous pulmonary venous return. The chest x-ray can aid in the assessment of pulmonary blood flow. Defects associated with left-to-right shunting have increased pulmonary blood flow (shunt vascularity) on x-ray. Right-to-left shunts have decreased pulmonary blood flow.


Pediatrics_Nelson

Pediatrics_Nelson. Echocardiography has become the most important noninvasive tool in the diagnosis and management of cardiac disease,providing a full anatomic evaluation in most congenital heartdefects (Fig. 139-4). Physiologic data on the direction of bloodflow can be obtained with the use of pulsed, continuous wave,and color flow Doppler. Imaging from multiple views providesan assessment of spatial relationships. Three-dimensional (3D)and four-dimensional (4D) imaging now allows reconstruction of the heart and manipulation of the images to providemore detail, especially with regard to valve structure and function. Prenatal or fetal echocardiography can diagnose congenital heart disease by 18 weeks of gestation and allows for delivery of the infant at a tertiary care hospital, improving thetimeliness of therapy. Many congenital heart defects now aresurgically repaired based on the echocardiogram without needfor cardiac catheterization.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 139-4 Four-chamber echocardiogram of an atrial septal defect. The defect margins are identified by the two arrows. LA, Left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. Transesophageal echocardiography (TEE) provides better imaging when transthoracic imaging is inadequate. It is used intraoperatively to assess results and cardiac function after surgery. TEE and intracardiac echocardiography are used to guide interventional catheterization and radiofrequency ablation of dysrhythmias.


Pediatrics_Nelson

Pediatrics_Nelson. Cardiac catheterization is performed in patients who needadditional anatomic information or precise hemodynamicinformation before operating or establishing a managementplan. Pressures, oxygen saturations, and oxygen content aremeasured in each chamber and blood vessel entered (Fig. 139-5). This information is used to calculate systemic andpulmonary blood flow and resistance. Angiography is performed by injecting contrast material into selected sites to define anatomy and supplement noninvasive information.An increasing percentage of cardiac catheterizations are doneto perform an intervention, including balloon dilation of stenotic valves and vessels, ballooning and stenting of stenoticlesions, closure of collateral vessels by coil embolization, anddevice closure of PDAs, secundum ASDs, patent foramen ovales, and muscular VSDs. Catheterization with electro-physiologic studies allows for precise mapping of the electrical activity, can assess the risk of abnormal heart rhythms,and often


Pediatrics_Nelson

Pediatrics_Nelson. foramen ovales, and muscular VSDs. Catheterization with electro-physiologic studies allows for precise mapping of the electrical activity, can assess the risk of abnormal heart rhythms,and often is done in anticipation of radiofrequency ablationof the site of a dysrhythmia.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 139-5 The normal heart. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle. Circled values are oxygen saturations. Available @ StudentConsult.com Syncope is the transient loss of consciousness and muscle tone that, by history, does not suggest other altered states of consciousness. Presyncope or near-syncope has many or all of the prodromal symptoms without loss of consciousness. Syncope is relatively common (Table 140-1). The frequency of episodes, amount of stress, and functional impairment caused by syncope vary. Most syncopal events are relatively benign, but can represent a serious cardiac condition that may lead to death (Table 140-1). The differential diagnosis for typical syncope includes seizure, metabolic cause (hypoglycemia), hyperventilation, atypical migraine, and breath holding.


Pediatrics_Nelson

Pediatrics_Nelson. Typical syncopal events usually occur in the upright position or are related to changing position. Syncope may be associated with anxiety, pain, blood drawing or the sight of blood, fasting, a hot environment, or crowded places. The patient often appears pale. A prodrome, consisting of dizziness, lightheadedness, nausea, diaphoresis, visual changes (blacking out), or possibly palpitations, warns the patient and often prevents Table 140-1 Syncope and Dizziness: Etiology DIAGNOSIS HISTORY SIGNS/ SYMPTOMS DESCRIPTION HEART RATE/ BLOOD PRESSURE DURATION POSTSYNCOPE RECURRENCE Neurocardiogenic (vasodepressor) At rest Pallor, nausea, visual changes Brief ± convulsion ↓/↓<1 min Residual pallor, sweaty, hot; recurs Common Micturition Postvoiding Pallor, nausea Brief; ↓/↓ < 1 min Carotid sinus Tight collar, Vague, visual Sudden onset, Usually ↓/↓ <5 min Fatigue or (+) turned head changes pallor Tumor or mass Recumbent, SOB ± chest Pallor ↑/↓ Any duration Baseline (+) paroxysmal pain


Pediatrics_Nelson

Pediatrics_Nelson. Tumor or mass Recumbent, SOB ± chest Pallor ↑/↓ Any duration Baseline (+) paroxysmal pain Coronary artery Exercise SOB ± chest Pallor ↑/↓ Any duration Fatigue, chest (+) disease From Lewis DA: Syncope and dizziness. In Kliegman RM, editor: Practical Strategies in Pediatric Diagnosis and Therapy, Philadelphia, 1996, WB Saunders. LVOT, Left ventricular outflow tract; SOB, shortness of breath; ±, with or without; (+), yes but not consistent or predictable. injury. Unconsciousness lasts for less than 1 minute. A return to normal consciousness occurs relatively quickly. Most of these syncopal episodes are vasovagal or neurocardiogenic in origin. The physical examination is normal.


Pediatrics_Nelson

Pediatrics_Nelson. Syncopal episodes may require no more than reassurance to the patient and family. If the episodes have a significant impact on daily activities, further evaluation may be indicated. An electrocardiogram (ECG) should be obtained with attention to the QTc and PR intervals (see Chapter 139). Although reassurance and increasing fluid and salt intake may be adequate to treat most cases of syncope, medical management is sometimes indicated. Available @ StudentConsult.com Chest pain in the pediatric patient often generates a significant amount of patient and parental concern. Although chest pain is rarely cardiac in origin in children, common knowledge about atherosclerotic heart disease raises concerns about a child experiencing chest pain. Most diagnosable chest pain in childhood is musculoskeletal in origin. A significant amount Anxiety, hyperventilation


Pediatrics_Nelson

Pediatrics_Nelson. Anxiety, hyperventilation Ischemia (coronary artery abnormalities, severe AS or PS, HOCM, cocaine) Infection/inflammation (myocarditis, pericarditis, Kawasaki disease) Dysrhythmia Abnormalities of rib cage/thoracic spine Tietze syndrome Slipping rib Tumor Pleurisy Pneumothorax, pneumomediastinum Pleural effusion Pulmonary embolism AS, Aortic stenosis; HOCM, hypertrophic obstructive cardiomyopathy; PS, pulmonary stenosis. remains idiopathic, however. Knowledge of the complete differential diagnosis is necessary to make an accurate assessment (Table 141-1).


Pediatrics_Nelson

Pediatrics_Nelson. remains idiopathic, however. Knowledge of the complete differential diagnosis is necessary to make an accurate assessment (Table 141-1). Assessment of a patient with chest pain includes a thorough history to determine activity at the onset; the location, radiation, quality, and duration of the pain; what makes the pain better and worse during the time that it is present; and any associated symptoms. A family history and assessment of how much anxiety the symptom is causing are important and often revealing. A careful general physical examination should focus on the chest wall, heart, lungs, and abdomen. A history of chest pain associated with exertion, syncope, or palpitations or acute onset associated with fever suggests a cardiac etiology. Cardiac causes of chest pain are generally ischemic, inflammatory, or arrhythmic in origin.


Pediatrics_Nelson

Pediatrics_Nelson. Tests rarely are indicated based on the history. A chest x-ray, electrocardiogram (ECG), 24-hour Holter monitoring, echo-cardiogram, and exercise stress testing may be obtained based on history and examination. Referral to a pediatric cardiologist is based on the history, physical examination findings, family history, and, frequently, the level of anxiety in the patient or family members regarding the pain. Available @ StudentConsult.com Cardiac dysrhythmias or abnormal heart rhythms are uncommon in pediatrics but may be caused by infection and inflammation, structural lesions, metabolic abnormalities, and intrinsic conduction abnormalities (Table 142-1). Many pediatric dysrhythmias are normal variants that do not require treatment or even further evaluation.


Pediatrics_Nelson

Pediatrics_Nelson. Sinus rhythm originates in the sinus node and has a normal axis P wave (upright in leads I and AVF) preceding each QRS complex. Because normal rates vary with age, sinus bradycardia and sinus tachycardia are defined based on age. Sinus arrhythmia is a common finding in children and represents a normal variation in the heart rate associated with breathing. The heart rate increases with inspiration and decreases with expiration, producing a recurring pattern on the electrocardiogram (ECG) tracing. Sinus arrhythmia is normal and does not require further evaluation or treatment. Intoxication (cocaine, tricyclic antidepressants, and others) Antiarrhythmic agents (proarrhythmic agents [quinidine]) Sympathomimetic agents (caffeine, theophylline, ephedrine, and Electrolyte disturbances (↓↑K+, ↓↑Ca2+, ↓Mg2+) Cardiomyopathy Thyrotoxicosis Uremia Pheochromocytoma Porphyria Mitochondrial myopathies


Pediatrics_Nelson

Pediatrics_Nelson. Electrolyte disturbances (↓↑K+, ↓↑Ca2+, ↓Mg2+) Cardiomyopathy Thyrotoxicosis Uremia Pheochromocytoma Porphyria Mitochondrial myopathies A wandering atrial pacemaker is a change in the morphology of the P waves with variable PR interval and normal QRS complex. This is a benign finding, requiring no further evaluation or treatment. Premature atrial contractions are relatively common prenatally and in infants. A premature P wave, usually with an abnormal axis consistent with its ectopic origin, is present. The premature atrial activity may be blocked (no QRS following it), conducted normally (normal QRS present), or conducted aberrantly (a widened, altered QRS complex). Premature atrial contractions are usually benign and, if present around the time of delivery, usually disappear during the first few weeks of life.


Pediatrics_Nelson

Pediatrics_Nelson. Atrial flutter and atrial fibrillation are uncommon dysrhythmias in pediatrics and usually present after surgical repairof complex congenital heart disease. They may also be seen inpatients with myocarditis or in association with drug toxicity.


Pediatrics_Nelson

Pediatrics_Nelson. Supraventricular tachycardia (SVT) is the most common symptomatic dysrhythmia in pediatric patients. The rhythm has a rapid, regular rate with a narrow QRS complex. SVT in infants is often 280 to 300 beats/minute with slower rates for older children and adolescents. The tachycardia has an abrupt onset and termination. In a child with a structurally normal heart, most episodes are relatively asymptomatic other than a pounding heartbeat. If there is structural heart disease or the episode is prolonged (>12 hours), there may be alteration in the cardiac output and development of symptoms of heart failure. Although most patients with SVT have structurally normal hearts and normal baseline ECGs, some children have Wolff-Parkinson-White syndrome or preexcitation as the cause of the dysrhythmia.


Pediatrics_Nelson

Pediatrics_Nelson. Premature ventricular contractions (PVCs) are less common than premature atrial contractions in infancy but more common in older children and adolescents (Table 142-2). The premature beat is not preceded by a P wave and the QRS complex is wide and bizarre. If the heart is structurally normal, and the PVCs are singleton, uniform in focus, and disappear with increased heart rate. The PVCs are usually benign and require no treatment. Any deviation from the presentation (history of syncope or a family history of sudden death) requires further investigation and possibly treatment with antiarrhythmic medications.


Pediatrics_Nelson

Pediatrics_Nelson. Ventricular tachycardia, defined as three or more consecutive PVCs, is also relatively rare in pediatric patients. Although there are multiple causes of ventricular tachycardia, it usually is a sign of serious cardiac dysfunction or disease. Rapid-rate ventricular tachycardia results in decreased cardiac output and cardiovascular instability. Treatment in symptomatic patients is synchronized cardioversion. Medical management with lidocaine or amiodarone may be appropriate in a conscious asymptomatic patient. Complete evaluation of the etiologic picture is necessary, including electrophysiologic study.


Pediatrics_Nelson

Pediatrics_Nelson. Firstdegree heart block is the presence of a prolonged PRinterval. It is asymptomatic and, when present in otherwisenormal children, requires no evaluation or treatment. Seconddegree heart block is when some, but not all, of the P waves are followed by a QRS complex. Mobitz type I (also known asWenckebach) is characterized by a progressive prolongationof the PR interval until a QRS complex is dropped. It is oftenseen during sleep, usually does not progress to other forms ofheart block, and does not require further evaluation or treatment in otherwise normal children. Mobitz type II is presentwhen the PR interval does not change, but a QRS is intermittently dropped. This form may progress to complete heart blockand may require pacemaker placement. Thirddegree heart block, whether congenital or acquired, is present when thereis no relationship between atrial and ventricular activity. Theventricular rate is much slower than the atrial rate. Congenital complete heart block is associated


Pediatrics_Nelson

Pediatrics_Nelson. or acquired, is present when thereis no relationship between atrial and ventricular activity. Theventricular rate is much slower than the atrial rate. Congenital complete heart block is associated with maternal collagen vascular disease (such as systemic lupus erythematosus or Sjögrensyndrome) or congenital heart disease. The acquired form mostoften occurs after cardiac surgery but may be secondary toinfection, inflammation, or drugs.


Pediatrics_Nelson

Pediatrics_Nelson. Supraventricular tachycardia Rate usually >220 beats/min (range, 180–320 beats/min); Increase vagal tone (bag of ice water to face, abnormal atrial rate for age; P waves may be present Valsalva maneuver); adenosine; digoxin; and are related to QRS complex; normal, narrow QRS sotalol; electrical cardioversion if acutely ill; complexes unless aberrant conduction is present catheter ablation Atrial flutter Atrial rate usually 300 beats/min, with varying degrees of Digoxin, sotalol, cardioversion block; sawtooth flutter waves Ventricular fibrillation No distinct QRS complex or T waves; irregular Nonsynchronized cardioversion undulations with varied amplitude and contour, no conducted pulse First-degree heart block Prolonged PR interval for age Observe, obtain digoxin level if on therapy


Pediatrics_Nelson

Pediatrics_Nelson. First-degree heart block Prolonged PR interval for age Observe, obtain digoxin level if on therapy Mobitz type I (Wenckebach) Progressive lengthening of PR interval until P wave is not Observe, correct underlying electrolyte or second-degree heart block followed by conducted QRS complex other abnormalities Mobitz type II second-degree Sudden nonconduction of P wave with loss of QRS Consider pacemaker heart block complex without progressive PR interval lengthening Sinus tachycardia Rate <240 beats/min Treat cause (fever), remove sympathomimetic drugs AV, Atrioventricular; ECG, electrocardiogram. Ia Prolongation of QRS complex and QT interval Quinidine, procainamide, disopyramide Ib Significant effect on abnormal conduction Lidocaine, mexiletine, phenytoin, tocainide Ic Prolongation of QRS complex and PR interval Flecainide, propafenone, moricizine? β blockade; slowing of sinus rate; prolongation of PR interval Propranolol, atenolol, acebutolol


Pediatrics_Nelson

Pediatrics_Nelson. Ic Prolongation of QRS complex and PR interval Flecainide, propafenone, moricizine? β blockade; slowing of sinus rate; prolongation of PR interval Propranolol, atenolol, acebutolol Prolongation of action potential; prolongation of PR, QT intervals, QRS Bretylium, amiodarone, sotalol complex; sodium and calcium channel blockade Calcium channel blockade; reduction in sinus and AV node pacemaker activity Verapamil and other calcium channel blocking and conduction; prolongation of PR interval agents AV, Atrioventricular.


Pediatrics_Nelson

Pediatrics_Nelson. Most atrial dysrhythmias require no intervention. Treatment of SVT depends on presentation and symptoms.Acute treatment of SVT in infants usually consists of vagal maneuvers, such as application of cold (ice bag) to the face.Intravenous (IV) adenosine usually converts the dysrhythmia because the atrioventricular node forms a part of thereentry circuit in most patients with SVT. In patients withcardiovascular compromise at the time of presentation, synchronized cardioversion is indicated using 1 to 2 J/kg. Inpatients with palpitations, it is important to document heartrate and rhythm during their symptoms before consideringtherapeutic options. The frequency, length, and associatedsymptoms during the episodes, as well as what is required to convert the rhythm, determine the need for treatment.Some patients require only education regarding the dysrhythmia and follow-up. Ongoing pharmacologic management with either digoxin or a β-blocker is usually the firstchoice. However, digoxin is


Pediatrics_Nelson

Pediatrics_Nelson. patients require only education regarding the dysrhythmia and follow-up. Ongoing pharmacologic management with either digoxin or a β-blocker is usually the firstchoice. However, digoxin is contraindicated in patientswith Wolff-Parkinson-White syndrome. Additional antiarrhythmic medications are rarely needed. In patients who aresymptomatic or those not wanting to take daily medications,radiofrequency ablation may be performed.


Pediatrics_Nelson

Pediatrics_Nelson. A variety of antiarrhythmic agents are used to treat ventricular dysrhythmias that require intervention (Table 142-3).Management of third-degree heart block depends on the ventricular rate and presence of symptoms. Treatment, if needed, often requires placement of a pacemaker. Available @ StudentConsult.com Congenital heart disease occurs in 8 per 1000 births. The spectrum of lesions ranges from asymptomatic to fatal. Although most cases of congenital heart disease are multifactorial, some lesions are associated with chromosomal disorders, single gene defects, teratogens, or maternal metabolic disease (see Table 139-2). Congenital heart defects can be divided into three pathophysiologic groups (Table 143-1). 1. 2. 3.


Pediatrics_Nelson

Pediatrics_Nelson. Congenital heart defects can be divided into three pathophysiologic groups (Table 143-1). 1. 2. 3. Obstructive, stenotic lesions Acyanotic congenital heart disease includes left-to-right shunts resulting in an increase in pulmonary blood flow (patent ductus arteriosus [PDA], ventricular septal defect [VSD], atrial septal defect [ASD]) and obstructive lesions (aortic stenosis, pulmonary stenosis, coarctation of the aorta), which usually have normal pulmonary blood flow.


Pediatrics_Nelson

Pediatrics_Nelson. The ventricular septum is a complex structure that can be divided into four components. The largest component is the muscular septum. The inlet or posterior septum comprises endocardial cushion tissue. The subarterial or supracristal septum comprises conotruncal tissue. The membranous septum is below the aortic valve and is relatively small. VSDs occur when any of these components fails to develop normally (Fig. 143-1). VSD, the most common congenital heart defect, accounts for 25% of all congenital heart disease. Perimembranous VSDs are the most common of all VSDs (67%).


Pediatrics_Nelson

Pediatrics_Nelson. Although the location of the VSD is important prognostically and in approach to repair, the amount of flow crossing a VSD depends on the size of the defect and the pulmonary vascular resistance. Large VSDs are not symptomatic at birth because the pulmonary vascular resistance is normally elevated at this time. As the pulmonary vascular resistance decreases over the first 6 to 8 weeks of life, the amount of shunt increases, and symptoms may develop. Small VSDs with little shunt are often asymptomatic but have a loud murmur. Moderate to large VSDs result in pulmonary Coarctation of Tricuspid Atrial septal HLH the aorta atresia defect HLH, Hypoplastic left heart syndrome; TAPVR, total anomalous pulmonary venous return. Figure 143-1 Ventricular septal defect. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 143-1 Ventricular septal defect. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle. overcirculation and heart failure. The typical physical finding with a VSD is a pansystolic murmur, usually heard best at the lower left sternal border. There may be a thrill. Large shunts increase flow across the mitral valve causing a middiastolic murmur at the apex. The splitting of S2 and intensity of P2 depend on the pulmonary artery pressure.


Pediatrics_Nelson

Pediatrics_Nelson. Electrocardiogram (ECG) and chest x-ray findings depend on the size of the VSD. Small VSDs usually have normal studies. Larger VSDs cause volume overload to the left side of the heart, resulting in ECG findings of left atrial and ventricular enlargement and hypertrophy. A chest x-ray may reveal cardiomegaly, enlargement of the left ventricle, an increase in the pulmonary artery silhouette, and increased pulmonary blood flow. Pulmonary hypertension due to either increased flow or increased pulmonary vascular resistance may lead to right ventricular enlargement and hypertrophy.


Pediatrics_Nelson

Pediatrics_Nelson. Approximately one third of all VSDs close spontaneously. Small VSDs usually close spontaneously and, if they do not close, surgical closure may not be required. Initial treatment for moderate to large VSDs includes diuretics (± digoxin) and afterload reduction. Continued poor growth or pulmonary hypertension despite therapy requires closure of the defect. Most VSDs are closed surgically, but some VSDs, especially muscular defects, can be closed with devices placed at cardiac catheterization. Figure 143-2 Atrial septal defect. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 143-2 Atrial septal defect. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle. During the embryologic development of the heart, a septum grows toward the endocardial cushions to divide the atria. Failure of septal growth or excessive reabsorption of tissue leads to ASDs (Fig. 143-2). ASDs represent approximately 10% of all congenital heart defects. A secundum defect, with the hole in the region of the foramen ovale, is the most common ASD. A primum ASD, located near the endocardial cushions, may be part of a complete atrioventricular canal defect or may be present with an intact ventricular septum. The least common ASD is the sinus venosus defect, which may be associated with anomalous pulmonary venous return.


Pediatrics_Nelson

Pediatrics_Nelson. The pathophysiology and amount of shunting depend on thesize of the defect and the relative compliance of the both ventricles. Even with large ASDs and significant shunts, infants andchildren are rarely symptomatic. A prominent right ventricular impulse at the left lower sternal border (LLSB) often can bepalpated. A soft (grade I or II) systolic ejection murmur in the region of the right ventricular outflow tract and a fixed split S2 (due to overload of the right ventricle with prolonged ejectioninto the pulmonary circuit) are often audible. A larger shuntmay result in a mid-diastolic murmur at the LLSB as a result ofthe increased volume passing across the tricuspid valve. ECG and chest x-ray findings reflect the increased blood flow through the right atrium, right ventricle, pulmonary arteries, Figure 143-3 Patent ductus arteriosus. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 143-3 Patent ductus arteriosus. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle. and lungs. The ECG may show right axis deviation and right ventricular enlargement. A chest radiograph may show cardiomegaly, right atrial enlargement, and a prominent pulmonary artery. Medical management is rarely indicated. If a significant shunt is still present at around 3 years of age, closure is usually recommended. Many secundum ASDs can be closed with an ASD closure device in the catheterization laboratory. Primum and sinus venosus defects require surgical closure.


Pediatrics_Nelson

Pediatrics_Nelson. The ductus arteriosus allows blood to flow from the pulmonary artery to the aorta during fetal life. Failure of the normal closure of this vessel results in a PDA (Fig. 143-3). With a falling pulmonary vascular resistance after birth, left-to-right shunting of blood and increased pulmonary blood flow occur. Excluding premature infants, PDAs represent approximately 5% to 10% of congenital heart disease. Symptoms depend on the amount of pulmonary blood flow. The magnitude of the shunt depends on the size of the PDA (diameter, length, and tortuosity) and the pulmonary vascular resistance. Small PDAs are asymptomatic; moderate to large shunts can produce the symptoms of heart failure as the pulmonary vascular resistance decreases.


Pediatrics_Nelson

Pediatrics_Nelson. The physical examination findings depend on the size of the shunt. A widened pulse pressure is often present as a result of the runoff of blood into the pulmonary circulation during diastole. A continuous, machinelike murmur can be heard at the left infraclavicular area, radiating along the pulmonary arteries and often well heard over the left side of the back. Larger shunts with increased flow across the mitral valve may result in a mid-diastolic murmur at the apex and a hyperdynamic precordium. Splitting of S2 and intensity of P2 depend on the pulmonary artery pressure. A thrill may be palpable. Figure 143-4 Atrioventricular canal defects. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 143-4 Atrioventricular canal defects. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle. ECG and chest x-ray findings are normal with small PDAs. Moderate to large shunts may result in a full pulmonary artery silhouette and increased pulmonary vascularity. ECG findings vary from normal to evidence of left ventricular hypertrophy. If pulmonary hypertension is present, there is also right ventricular hypertrophy. Spontaneous closure of a PDA after a few weeks of age is uncommon in full-term infants. Moderate and large PDAs may be managed initially with diuretics, but eventually require closure. Elective closure of small, hemodynamically insignificant PDAs is controversial. Most PDAs can be closed in the catheterization laboratory by either coil embolization or a PDA closure device.


Pediatrics_Nelson

Pediatrics_Nelson. Endocardial cushion defects, also referred to as atrioventricular canal defects, may be complete or partial (Fig. 143-4).Failure of the septum to fuse with the endocardial cushion results in abnormal atrioventricular valves as well. The complete defect results in a primum ASD, a posterior or inlet VSD, and clefts in the anterior leaflet of the mitral and septal leaflet of the tricuspid valves. In addition to left-to-right shunting at both levels, there may be atrioventricular valve insufficiency.


Pediatrics_Nelson

Pediatrics_Nelson. The symptoms of heart failure usually develop as the pulmonary vascular resistance decreases over the first 6 to 8 weeks of life. Symptoms may be earlier and more severe with significant atrioventricular valve insufficiency. Pulmonary hypertension resulting from increased pulmonary circulation often develops early. The presence of murmurs varies depending on the amount of shunting at both atrial and ventricular levels. If there is a large VSD component, S2 will be single. Growth is usually poor. Complete endocardial cushion defects are most commonly seen in children with Down syndrome. The diagnosis usually is made with echocardiography. A chest radiograph reveals cardiomegaly with enlargement of all chambers and the presence of increased vascularity. An ECG reveals left axis deviation and combined ventricular hypertrophy and may show combined atrial enlargement.


Pediatrics_Nelson

Pediatrics_Nelson. Initial management includes diuretics (± digoxin) and after-load reduction for treatment of heart failure. Surgical repair of the defect ultimately is required. Pulmonary stenosis accounts for approximately 10% of all congenital heart disease and can be valvular, subvalvular, or supravalvular in nature. Pulmonary stenosis results from the failure of the development, in early gestation, of the three leaflets of the valve, insufficient resorption of infundibular tissue, or insufficient canalization of the peripheral pulmonary arteries. Symptoms depend on the degree of obstruction present. Mild pulmonary stenosis is asymptomatic. Moderate to severe stenosis results in exertional dyspnea and easy fatigability. Newborns with severe stenosis may be more symptomatic and even cyanotic because of right-to-left shunting at the atrial level.


Pediatrics_Nelson

Pediatrics_Nelson. Pulmonary stenosis causes a systolic ejection murmur at the second left intercostal space which radiates to the back. A thrill may be present. S2 may be widely split with a quiet pulmonary component. With more severe pulmonary stenosis, an impulse at the lower left sternal border results from right ventricular hypertrophy. Valvular stenosis may result in a click that varies with respiration. Worsening stenosis causes an increase in the duration of the murmur and a higher frequency of the sound. The systolic ejection murmurs of peripheral pulmonary stenosis are heard distal to the site of obstruction in the pulmonary circulation, including radiation to the back.


Pediatrics_Nelson

Pediatrics_Nelson. ECG and chest x-ray findings are normal in mild stenosis. Moderate to severe stenosis results in right axis deviation and right ventricular hypertrophy. The heart size is usually normal on chest x-ray, although dilation of the main pulmonary artery may be seen. Echocardiography provides assessment of the site of stenosis, degree of hypertrophy, and valve morphology, as well as an estimate of the pressure gradient. Valvular pulmonary stenosis usually does not progress, especially if it is mild. Balloon valvuloplasty is usually successful in reducing the gradient to acceptable levels for more significant or symptomatic stenosis. Surgical repair is required if balloon valvuloplasty is unsuccessful or when subvalvular (muscular) stenosis is present. Valvular, subvalvular, or supravalvular aortic stenosis represents approximately 5% of all congenital heart disease. Lesions result from failure of development of the three leaflets or failure of resorption of tissue around the valve.


Pediatrics_Nelson

Pediatrics_Nelson. Mild to moderate obstructions cause no symptoms. More severe stenosis results in easy fatigability, exertional chest pain, and syncope. Infants with critical aortic stenosis may present with symptoms of heart failure. A systolic ejection murmur is heard at the right second intercostal space along the sternum and radiating into the neck. The murmur increases in length and becomes higher in frequency as the degree of stenosis increases. With valvular stenosis, a systolic ejection click often is heard, and a thrill may be present at the right upper sternal border or in the suprasternal notch. The aortic component of S2 may be decreased in intensity.


Pediatrics_Nelson

Pediatrics_Nelson. ECG and chest x-ray findings are normal with mild degrees of stenosis. Left ventricular hypertrophy develops with moderate to severe stenosis and is detected on the ECG and chest x-ray. Dilation of the ascending aorta or aortic knob due to an intrinsic aortopathy may be seen on chest radiographs. Echocardiography shows the site of stenosis, valve morphology, and the presence of left ventricular hypertrophy, and it allows an estimate of the pressure gradient. The degree of aortic stenosis frequently progresses with growth and age. Aortic insufficiency often develops or progresses. Serial follow-up with echocardiography is indicated. Balloon valvuloplasty is usually the first interventional procedure for significant stenosis. It is not as successful as pulmonary balloon valvuloplasty and has a higher risk of significant valvular insufficiency. Surgical management is necessary when balloon valvuloplasty is unsuccessful or significant valve insufficiency develops.


Pediatrics_Nelson

Pediatrics_Nelson. Coarctation of the aorta occurs in approximately 10% of all congenital heart defects. It is almost always juxtaductal in position. During development of the aortic arch, the area near the insertion of the ductus arteriosus fails to develop correctly, resulting in a narrowing of the aortic lumen. Timing of presentation depends on the severity of obstruction and associated cardiac defects. Infants presenting withcoarctation of the aorta frequently have hypoplastic aortic arches, abnormal aortic valves, and VSDs. They may bedependent on a patent ductus arteriosus to provide descending aortic flow. Symptoms develop when the aortic ampullaof the ductus closes. Less severe obstruction causes no symptoms.


Pediatrics_Nelson

Pediatrics_Nelson. Symptoms, including poor feeding, respiratory distress, and shock, may develop before 2 weeks of age. Classically thefemoral pulses are weaker and delayed compared with theright radial pulse. The blood pressure in the lower extremities is lower than that in the upper extremities. If cardiac function is poor, however, these differences may not be asapparent until appropriate resuscitation is accomplished. Inthis situation, there may be no murmur, but an S3 is often present.


Pediatrics_Nelson

Pediatrics_Nelson. Older children presenting with coarctation of the aorta are usually asymptomatic. There may be a history of leg discomfort with exercise, headache, or epistaxis. Decreasedor absent lower extremity pulses, hypertension (upperextremity), or a murmur may be present. The murmur istypically best heard in the left interscapular area of the back.If significant collaterals have developed, continuous murmurs may be heard throughout the chest. An abnormal aortic valve is present approximately 50% of the time, causing asystolic ejection click and systolic ejection murmur of aorticstenosis.


Pediatrics_Nelson

Pediatrics_Nelson. The ECG and chest x-ray show evidence of right ventricular enlargement and hypertrophy in infantile coarctation with marked cardiomegaly and pulmonary edema. Echocardiography shows the site of coarctation and associated lesions. In older children, the ECG and chest x-ray usually show left ventricular hypertrophy and a mildly enlarged heart. Rib notching may also be seen in older children (>8 years of age) with large collaterals. Echocardiography shows the site and degree of coarctation, presence of left ventricular hypertrophy, and aortic valve morphology and function.


Pediatrics_Nelson

Pediatrics_Nelson. Management of an infant presenting with cardiac decompensation includes intravenous infusion of prostaglandin E1 (chemically opens the ductus arteriosus), inotropic agents, diuretics, and other supportive care. Balloon angioplastyhas been done, especially in critically ill infants, but surgical repair of the coarctation is most commonly performed. Ballooning and stenting of older patients with coarctation has become more accepted as primary therapy, but surgical repair remains a common form of management. Available @ StudentConsult.com


Pediatrics_Nelson

Pediatrics_Nelson. Available @ StudentConsult.com Cyanotic congenital heart disease occurs when some of the systemic venous return crosses from the right side of the heart to the left and returns to the body without going through the lungs (righttoleft shunt). Cyanosis, the visible sign of this shunt, occurs when approximately 5 g/100 mL of reduced hemoglobin is present in systemic blood. Thus, a polycythemic patient appears cyanotic with a lower percentage of reduced hemoglobin. A patient with anemia requires a higher percentage of reduced hemoglobin for the recognition of cyanosis. The most common cyanotic congenital heart defects are the five Ts: Tetralogy of FallotTransposition of the great arteriesTricuspid atresiaTruncus arteriosus Total anomalous pulmonary venous return


Pediatrics_Nelson

Pediatrics_Nelson. The most common cyanotic congenital heart defects are the five Ts: Tetralogy of FallotTransposition of the great arteriesTricuspid atresiaTruncus arteriosus Total anomalous pulmonary venous return Other congenital heart defects that allow complete mixing of systemic and pulmonary venous return can present with cyanosis depending on the amount of pulmonary blood flow that is present. Many cyanotic heart lesions present in the neonatal period (Table 144-1).


Pediatrics_Nelson

Pediatrics_Nelson. Tetralogy of Fallot is the most common cyanotic congenital heart defect, representing about 10% of all congenital heart defects (Fig. 144-1). There are four structural defects: ventricular septal defect (VSD), pulmonary stenosis, overriding aorta, and right ventricular hypertrophy. Tetralogy of Fallot is due to abnormal septation of the truncus arteriosus into the aorta and pulmonary artery that occurs early in gestation (3to 4 weeks). The VSD is large and the pulmonary stenosis is most commonly subvalvular or infundibular. It may also be valvular, supravalvular, or, frequently, a combination of levels of obstruction.


Pediatrics_Nelson

Pediatrics_Nelson. Infants initially may be acyanotic. A pulmonary stenosis murmur is the usual initial abnormal finding. The amount of right-to-left shunting at the VSD (and the degree of cyanosis) increases as the degree of pulmonary stenosis increases. With increasing severity of pulmonary stenosis, the murmur becomes shorter and softer. In addition to varying degrees of cyanosis and a murmur, a single S2 and right ventricular impulse at the left sternal border are typical findings. When hypoxic (Tet) spells occur, they are usually progressive. During a spell, the child typically becomes restless and agitated and may cry inconsolably. An ambulatory toddler may ASD, Atrial septal defect; AV, atrioventricular; AVM, arteriovenous malformation; PDA, patent ductus arteriosus; VSD, ventricular septal defect. Figure 144-1 Tetralogy of Fallot. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 144-1 Tetralogy of Fallot. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle. squat. Hyperpnea occurs with gradually increasing cyanosis and loss of the murmur. In severe spells, prolonged unconsciousness and convulsions, hemiparesis, or death may occur. Independent of hypoxic spells, patients with unrepaired tetralogy of Fallot are at increased risk for cerebral thromboembolism and cerebral abscesses resulting, in part, from their right-to-left intracardiac shunt.


Pediatrics_Nelson

Pediatrics_Nelson. The electrocardiogram (ECG) usually has right axis deviation and right ventricular hypertrophy. The classic chest x-ray finding is a bootshaped heart created by the small main pulmonaryartery and upturned apex secondary to right ventricular hypertrophy. Echocardiography shows the anatomic features, including the anatomic level and quantification of pulmonary stenosis.Coronary anomalies, most commonly a left anterior descendingcoronary artery arising from the right coronary artery and crossing the anterior surface of the right ventricular outflow tract, arepresent in 5% of patients with tetralogy of Fallot.


Pediatrics_Nelson

Pediatrics_Nelson. The natural history of tetralogy of Fallot is progression of pulmonary stenosis and cyanosis. Treatment of hypoxic spells consists of oxygen administration and placing the child in the knee-chest position (to increase venous return). Traditionally, morphine sulfate is given (to relax the pulmonary infundibulum and for sedation). If necessary, the systemic vascular resistance can be increased acutely through the administration of an α-adrenergic agonist (phenylephrine). The occurrence of a cyanotic spell is an indication to proceed with surgical repair.


Pediatrics_Nelson

Pediatrics_Nelson. Complete surgical repair with VSD closure and removal or patching of the pulmonary stenosis can be performed in infancy. Occasionally, palliative shunt surgery between the subclavian artery and pulmonary artery is performed for complex forms of tetralogy of Fallot and more complete repair is done at a later time. Subacute bacterial endocarditis prophylaxis is indicated until 6 months after complete repair unless there is a residual VSD. Prophylaxis is then continued as long as there is a residual VSD. Figure 144-2 Transposition of the great vessels. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


Pediatrics_Nelson

Pediatrics_Nelson. Although dextroposed transposition of the great arteries represents only about 5% of congenital heart defects, it is the mostcommon cyanotic lesion to present in the newborn period(Fig. 144-2). Transposition of the great arteries is ventriculoarterial discordance secondary to abnormalities of septationof the truncus arteriosus. In dextroposed transposition, theaorta arises from the right ventricle, anterior and to the rightof the pulmonary artery, which arises from the left ventricle.This results in desaturated blood returning to the right sideof the heart and being pumped back out to the body, whilewell-oxygenated blood returning from the lungs enters the leftside of the heart and is pumped back to the lungs. Withoutmixing of the two circulations, death occurs quickly. Mixing can occur at the atrial (patent foramen ovale/atrial septal defect [ASD]), ventricular [VSD], or great vessel (patentductus arteriosus [PDA]) level.


Pediatrics_Nelson

Pediatrics_Nelson. A history of cyanosis is always present, although it depends on the amount of mixing. Quiet tachypnea and a single S2 are typically present. If the ventricular septum is intact, there may be no murmur. Children with transposition and a large VSD have improved intracardiac mixing and less cyanosis. They may present with signs of heart failure. The heart is hyperdynamic, with palpable left and right ventricular impulses. A loud VSD murmur is heard. S2 is single. ECG findings typically include right axis deviation and right ventricular hypertrophy. The chest x-ray reveals increased pulmonary vascularity, and the cardiac shadow is classically an egg on a string created by the narrow superior mediastinum. Echocardiography shows the transposition of the great arteries, the sites and amount of mixing, and any associated lesions. Figure 144-3 Tricuspid atresia with ventricular septal defect. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 144-3 Tricuspid atresia with ventricular septal defect. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium. Initial medical management includes prostaglandin E1 to maintain ductal patency. If significant hypoxia persists on prostaglandin therapy, a balloon atrial septostomy improves mixing between the two circulations. Complete surgical repair is most often an arterial switch. The arterial switch usually is performed within the first 2 weeks of life, when the left ventricle can still maintain systemic pressure. Tricuspid atresia accounts for approximately 2% of all congenital heart defects (Fig. 144-3). The absence of the tricuspid valve results in a hypoplastic right ventricle. All systemic venous return must cross the atrial septum into the left atrium. A PDA or VSD is necessary for pulmonary blood flow and survival.


Pediatrics_Nelson

Pediatrics_Nelson. Infants with tricuspid atresia are usually severely cyanotic and have a single S2. If a VSD is present, there may be a murmur. A diastolic murmur across the mitral valve may be audible. Frequently there is no significant murmur. The ECG shows left ventricular hypertrophy and a superior QRS axis (between 0° and –90°). The chest x-ray reveals a normal or mildly enlarged cardiac silhouette with decreased pulmonary blood flow. Echocardiography shows the anatomy, associated lesions, and source of pulmonary blood flow. Management initially depends on the presence of a VSD and the amount of antegrade blood flow to the lungs. If there is no VSD, or it is small, prostaglandin E1 maintains pulmonary Figure 144-4 Truncus arteriosus. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 144-4 Truncus arteriosus. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle. blood flow until surgery. Surgery is staged with an initial subclavian artery-to-pulmonary shunt (BlalockTaussig procedure)typically followed by a two-stage procedure: bidirectional cavopulmonary shunt (bidirectional Glenn) and Fontan procedure. These surgeries direct systemic venous return directly to the pulmonary arteries. Truncus arteriosus occurs in less than 1% of all cases of congenital heart disease (Fig. 144-4). It results from the failure of septation of the truncus during the first 3 to 4 weeks of gestation. A single arterial trunk arises from the heart with a large VSD immediately below the truncal valve. The pulmonary arteries arise from the single arterial trunk either as a single vessel that divides or individually from the arterial trunk to the lungs.


Pediatrics_Nelson

Pediatrics_Nelson. Varying degrees of cyanosis depend on the amount of pulmonary blood flow. If not diagnosed at birth, the infantmay develop signs of heart failure as pulmonary vascularresistance decreases. The signs then include tachypnea andcough. Peripheral pulses are usually bounding as a result ofthe diastolic runoff into the pulmonary arteries. A single S2 is due to the single valve. There may be a systolic ejection click, and there is often a systolic murmur at the left sternal border. ECG findings include combined ventricular hypertrophy and cardiomegaly. A chest x-ray usually reveals increased pulmonary blood and may show displaced pulmonary arteries. Echocardiography defines the anatomy, including theVSD, truncal valve function, and origin of the pulmonaryarteries.


Pediatrics_Nelson

Pediatrics_Nelson. Figure 144-5 Total anomalous pulmonary venous return. AO, Aorta; IVC, inferior vena cava; LA, left atrium; LV, left ventricle; PA, pulmonary artery; PV, pulmonary vein; RA, right atrium; RV, right ventricle; SVC, superior vena cava. Medical management is usually needed and includes anticongestive medications. Surgical repair includes VSD closure and placement of a conduit between the right ventricle and pulmonary arteries. Total anomalous pulmonary venous return accounts for about 1% of congenital heart disease (Fig. 144-5). Disruption of the development of normal pulmonary venous drainage during the third week of gestation results in one of four abnormalities. All of the pulmonary veins fail to connect to the left atrium and return abnormally via the right side of the heart. They may have supracardiac, infracardiac, cardiac, or mixed drainage. An atrial-level communication is required for systemic cardiac output and survival.


Pediatrics_Nelson

Pediatrics_Nelson. The most important determinant of presentation is the presenceor absence of obstruction to the pulmonary venous drainage.Infants without obstruction have minimal cyanosis and may beasymptomatic. There is a hyperactive right ventricular impulse with a widely split S2 (owing to increased right ventricular volume) and a systolic ejection murmur at the left upper sternalborder. There is usually a mid-diastolic murmur at the lowerleft sternal border from the increased flow across the tricuspidvalve. Growth is relatively poor. Infants with obstruction present with cyanosis, marked tachypnea and dyspnea, and signs ofright-sided heart failure including hepatomegaly. The obstruction results in little, if any, increase in right ventricular volume,so there may be no murmur or changes in S2. For infants without obstruction, the ECG is consistent with right ventricular volume overload. Cardiomegaly with


Pediatrics_Nelson

Pediatrics_Nelson. For infants without obstruction, the ECG is consistent with right ventricular volume overload. Cardiomegaly with Figure 144-6 Hypoplastic left side of the heart. AO, Aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; PDA, patent ductus arteriosus; RA, right atrium; RV, right ventricle. increased pulmonary blood flow is seen on chest x-ray. Infants with obstructed veins have right axis deviation and right ventricular hypertrophy on ECG. On chest x-ray, the heart is normal or mildly enlarged with varying degrees of pulmonary edema that can appear similar to hyaline membrane disease or pneumonia. Echocardiography shows the volume-overloaded right side of the heart, right-to-left atrial level shunting, and common pulmonary vein site of drainage and degree of obstruction. At surgery, the common pulmonary vein is opened into the left atrium, and there is ligation of any vein or channel that had been draining the common vein.


Pediatrics_Nelson

Pediatrics_Nelson. At surgery, the common pulmonary vein is opened into the left atrium, and there is ligation of any vein or channel that had been draining the common vein. Hypoplastic left heart syndrome accounts for 1% of all congenital heart defects (Fig. 144-6) but is the most common cause of death from cardiac defects in the first month of life. Hypoplastic left heart syndrome occurs when there is failure of development of the mitral or aortic valve or the aortic arch. A small left ventricle that is unable to support normal systemic circulation is a central finding, regardless of etiology. Associated degrees of hypoplasia of the ascending aorta and aortic arch are present. Left-to-right shunting occurs at the atrial level.


Pediatrics_Nelson

Pediatrics_Nelson. The newborn is dependent on right-to-left shunting at the ductus arteriosus for systemic blood flow. As the ductus arteriosus constricts, the infant becomes critically ill with signs and symptoms of heart failure from excessive pulmonary blood flow and obstruction of systemic blood flow. Pulses are diffusely weak or absent. S2 is single and loud. There is usually no heart murmur. Cyanosis may be minimal, but low cardiac output gives a grayish color to the cool, mottled skin. CNS abscess Right-to-left shunting Antibiotics, drainage Gingival disease Polycythemia, gingivitis, bleeding Dental hygiene Gout Polycythemia, diuretic agents Allopurinol Arthritis, clubbing Hypoxic arthropathy None Pregnancy Poor placental perfusion, poor ability to increase cardiac output Bed rest Infectious disease Associated asplenia, DiGeorge syndrome Antibiotics Fatal RSV pneumonia with pulmonary hypertension Ribavirin, RSV immune globulin


Pediatrics_Nelson

Pediatrics_Nelson. Infectious disease Associated asplenia, DiGeorge syndrome Antibiotics Fatal RSV pneumonia with pulmonary hypertension Ribavirin, RSV immune globulin Growth Failure to thrive, increased oxygen consumption, decreased Treat heart failure; correct defect early nutrient intake Psychosocial adjustment Limited activity, peer pressure; chronic disease, multiple Counseling hospitalizations, cardiac surgical techniques CNS, Central nervous system; RSV, respiratory syncytial virus. ECG findings include right ventricular hypertrophy with decreased left ventricular forces. The chest x-ray reveals car


Pediatrics_Nelson

Pediatrics_Nelson. Figure 145-1 Ventricular function curve illustrating the effect of inotropic agents or arterial vasodilators. In contrast to diuretics, the effect of digitalis or arterial vasodilator therapy in a patient with heart failure is movement onto another ventricular function curve intermediate between the normal and the depressed curves. When the patient’s ventricular function moves from A to B by the administration of one of these agents, the left ventricular end-diastolic pressure may also decrease because of improved cardiac function; further administration of diuretics or venodilators may shift the function further to the left along the same curve from B to C and eliminate the risk of pulmonary edema. A vasodilating agent that has arteriolar and venous dilating properties (e.g., nitroprusside) would shift this function directly from A to C. If this agent shifts the function from A to D because of excessive venodilation or administration of diuretics, the cardiac output may decrease too


Pediatrics_Nelson

Pediatrics_Nelson. would shift this function directly from A to C. If this agent shifts the function from A to D because of excessive venodilation or administration of diuretics, the cardiac output may decrease too much, even though the left ventricular end-diastolic pressure would be normal (10 mm Hg) for a normal heart. Left ventricular end-diastolic pressures of 15 to 18 mm Hg are usually optimal in the failing heart to maximize cardiac output, but to avoid pulmonary edema. (From Andreoli TE, Carpenter CCJ, Griggs RC, Loscalzo J, editors: Cecil essentials of medicine, ed 5, Philadelphia, Saunders, 2001.) pulmonary edema. Echocardiographyshows the small left side of the heart, the degree of stenosis of theaortic and mitral valves, the hypoplastic ascending aorta, and the adequacy of left-to-right atrial flow and right-to-left ductal flow.


Pediatrics_Nelson

Pediatrics_Nelson. Medical management includes prostaglandin E1 to open the ductus arteriosus, correction of acidosis, and ventilatory and blood pressure support as needed. Surgical repair is stagedwith the first surgery (Norwood procedure) done in the newborn period. Subsequent procedures create a systemic source for the pulmonary circulation (bidirectional Glenn and Fontan procedures), leaving the right ventricle to supply systemic circulation. There have been many modifications to all three stages of the repair. Prognosis for survival has improved significantly over the past two decades. Extracardiac complications are summarized in Table 144-2.


Pediatrics_Nelson

Pediatrics_Nelson. Extracardiac complications are summarized in Table 144-2. The force generated by the cardiac muscle fiber depends onits contractile status and basal length, which is equivalent to the preload. As the preload (fiber length, left ventricular filling pressure, or volume) increases, myocardial performance(stroke volume and wall tension) increases up to a point (thenormal Starling curve). The relationship is the ventricular function curve (Fig. 145-1). Alterations in the contractilestate of the muscle lower the relative position of the curve,but retain the relationship of fiber length to muscle work.Heart rate is another important determinant of cardiac work because the cardiac output equals stroke volume times theheart rate. Additional factors also affect cardiac performance(Table 145-1).


Pediatrics_Nelson

Pediatrics_Nelson. Heart failure occurs when the heart is unable to pump blood at a rate commensurate with metabolic needs (oxygen delivery). It may be due to a change in myocardial contractility that results in low cardiac output or to abnormal loading conditions being placed on the myocardium. The abnormal loading conditions may be afterload (pressure overload, such as with aortic stenosis, pulmonary stenosis, or coarctation of the aorta) or preload (volume overload, such as in ventricular septal defect (VSD), patent ductus arteriosus (PDA), or valvular insufficiency. Volume overload is the most common cause of heart failure in children.


Pediatrics_Nelson

Pediatrics_Nelson. The age of presentation is helpful in creating the differential diagnosis (Table 145-2). In the first weeks of life, excessive afterload being placed on the myocardium is most common. Heart failure presenting around 2 months of age is usually due to increasing left-to-right shunts that become apparent as the pulmonary vascular resistance decreases. Acquired heart disease, such as myocarditis and cardiomyopathy, can present at any age. Total blood volume Venous tone (sympathetic tone) Body position Intrathoracic and intrapericardial pressure Atrial contraction Pumping action of skeletal muscle Peripheral vascular resistance Left ventricular volume (preload, wall tension) Physical characteristics of the arterial tree (elasticity of vessels or presence of outflow obstruction)


Pediatrics_Nelson

Pediatrics_Nelson. Peripheral vascular resistance Left ventricular volume (preload, wall tension) Physical characteristics of the arterial tree (elasticity of vessels or presence of outflow obstruction) Sympathetic nerve impulses* Circulating catecholamines* Digitalis, calcium, other inotropic agents* Increased heart rate or postextrasystolic augmentation* Anoxia, acidosis† Pharmacologic depression† Loss of myocardium† Intrinsic depression† Autonomic nervous system Temperature, metabolic rate From Andreoli TE, Carpenter CCJ, Griggs RC, Loscalzo J: Cecil Essentials of Medicine, ed 5, Philadelphia, 2001, Saunders. *Increases contractility. †Decreases contractility. Severe anemia (hemolysis, fetal-maternal transfusion, hypoplastic anemia) Supraventricular tachycardia Ventricular tachycardia Complete heart block Atrioventricular valve insufficiency High-output cardiac failure (arteriovenous malformation, teratoma)


Pediatrics_Nelson

Pediatrics_Nelson. Asphyxial cardiomyopathy Arteriovenous malformation (vein of Galen, hepatic) Left-sided obstructive lesions (coarctation of aorta, hypoplastic left heart, critical aortic stenosis) Transposition of great arteries Large mixing cardiac defects (single ventricle, truncus arteriosus) Viral myocarditis Anemia Supraventricular tachycardia Complete heart block Left-to-right cardiac shunts (VSD) Hemangioma (arteriovenous malformation) Anomalous left coronary artery Metabolic cardiomyopathy Acute hypertension (hemolytic uremic syndrome) Supraventricular tachycardia Kawasaki disease Postoperative repair of congenital heart disease Rheumatic fever Acute hypertension (glomerulonephritis) Viral myocarditis Thyrotoxicosis Hemochromatosis/hemosiderosis Cancer therapy (radiation, doxorubicin) Sickle cell anemia Endocarditis Cor pulmonale (cystic fibrosis) Arrhythmias Chronic upper airway obstruction (cor pulmonale) Unrepaired or palliated congenital heart disease Cardiomyopathy


Pediatrics_Nelson

Pediatrics_Nelson. BPD, Bronchopulmonary dysplasia; PDA, patent ductus arteriosus; VSD, ventricular septal defect. Available @ StudentConsult.com Heart failure presents in infants as poor feeding, failure to thrive, tachypnea, and diaphoresis with feeding. Older children may present with shortness of breath, easy fatigability, and edema. The physical examination findings depend on whether pulmonary venous congestion, systemic venous congestion, or both are present. Tachycardia, a gallop rhythm, and thready pulses may be present with either cause. If left-sided Oxygen Improves oxygenation in presence of pulmonary edema Sodium, fluid Decreases vascular congestion; decreases restrictions preload Furosemide Salt excretion by way of ascending loop of Henle; reduces preload; afterload reduced with control of hypertension; may also cause venodilation Combination of Greater sodium excretion distal tubule and loop diuretics


Pediatrics_Nelson

Pediatrics_Nelson. Combination of Greater sodium excretion distal tubule and loop diuretics Digitalis Inhibits membrane Na+, K+-ATPase and increases intracellular Ca2+, improves cardiac contractility, increases myocardial oxygen consumption Dopamine Releases myocardial norepinephrine plus direct effect on β-receptor, may increase systemic blood pressure; at low infusion rates, dilates renal artery, facilitating diuresis Dobutamine β1-Receptor agent; often combined with dopamine Amrinone/ Nonsympathomimetic, noncardiac glycosides milrinone with inotropic effects; may cause vasodilation Captopril/enalapril Inhibition of angiotensin-converting enzyme; reduces angiotensin II production Mechanical Improves coronary flow, afterload counterpulsation failure is predominant, tachypnea, orthopnea, wheezing, and pulmonary edema are seen. Hepatomegaly, edema, and distended neck veins are signs of right-sided failure.


Pediatrics_Nelson

Pediatrics_Nelson. The absence of cardiomegaly on a chest x-ray usually rules out the diagnosis of heart failure. An echocardiogram assesses the heart chamber sizes, measures myocardial function, and diagnoses congenital heart defects when present. Initial treatment is directed at improving myocardial function and optimizing preload and afterload. Diuretics, inotropic support, and, often, afterload reduction are employed (Table 145-3). Long-term therapy usually consists of diuretics and afterload reduction is added. Long-term therapy withβblockers also may be beneficial, although this remainssomewhat controversial in pediatric patients. Spironolactoneis usually added to the medical regimen because of its effecton cardiac remodeling.


Pediatrics_Nelson

Pediatrics_Nelson. Although uncommon in the United States, acute rheumatic fever remains an important preventable cause of cardiac disease. It is most common in children 6 to 15 years of age. It is due to an immunologic reaction that is a delayed sequela of group A beta-hemolytic streptococcal infections of the pharynx. A family history of rheumatic fever and lower socioeconomic status are additional factors. Available @ StudentConsult.com Acute rheumatic fever is diagnosed using the clinical and laboratory findings of the revised Jones criteria (Table 146-1).The presence of either two major criteria or one major and two minor criteria, along with evidence of an antecedent streptococcal infection, confirm a diagnosis of acute rheumatic fever. The infection often precedes the presentation of rheumatic fever by 2 to 6 weeks. Streptococcal antibody tests, such as the antistreptolysin O titer, are the most reliable laboratory evidence of prior infection.


Pediatrics_Nelson

Pediatrics_Nelson. Table 146-1 Major Jones Criteria for Diagnosis of Acute Rheumatic Fever*,† Polyarthritis Common; swelling, limited motion, tender, erythema Migratory; involves large joints but rarely small or unusual joints, such as vertebrae Carditis Common; pancarditis, valves, pericardium, myocardium Tachycardia greater than explained by fever; new murmur of mitral or aortic insufficiency; Carey-Coombs mid-diastolic murmur; heart failure marginatum proximal extremities, evolving to serpiginous border with central clearing; evanescent, elicited by application of local heat; nonpruritic Subcutaneous Uncommon; associated with repeated nodules episodes and severe carditis; located over extensor surface of elbows, knees, knuckles, and ankles or scalp and spine; firm, nontender *Minor criteria include fever (temperatures of 101°–102°F [38.2°–38.9°C]), arthralgias, previous rheumatic fever, leukocytosis, elevated erythrocyte sedimentation rate/C-reactive protein, and prolonged PR interval.


Pediatrics_Nelson

Pediatrics_Nelson. †One major and two minor, or two major, criteria with evidence of recent group A streptococcal disease (e.g., scarlet fever, positive throat culture, or elevated antistreptolysin O or other antistreptococcal antibodies) strongly suggest the diagnosis of acute rheumatic fever.


Pediatrics_Nelson

Pediatrics_Nelson. Arthritis is the most common major manifestation. It usually involves the large joints and is migratory. Arthralgia cannot be used as a minor manifestation if arthritis is used as a major manifestation. Carditis occurs in about 50% of patients. Tachycardia, a new murmur (mitral or aortic regurgitation), pericarditis, cardiomegaly, and signs of heart failure are evidence of carditis. Erythema marginatum, a serpiginous, nonpruritic, and evanescent rash, is uncommon, occurs on the trunk, and is brought out by warmth. Subcutaneous nodules are seen predominantly with chronic or recurrent disease. They are firm, painless, nonpruritic, mobile nodules found on the extensor surfaces of the large and small joints, the scalp, and the spine. Chorea (Sydenham chorea or St. Vitus dance) consists of neurologic and psychiatric signs. It also is uncommon and often presents long after the infection.


Pediatrics_Nelson

Pediatrics_Nelson. Management of acute rheumatic fever consists of benzathine penicillin to eradicate the beta-hemolytic streptococcus, anti-inflammatory therapy with salicylates, and bed rest. Additional supportive therapy for heart failure or chorea may be necessary. Longterm penicillin prophylaxis, preferably with intramuscular benzathine penicillin G, 1.2 million U every 28 days, is required. Oral regimens for prophylaxis generally are not as effective. The prognosis of acute rheumatic fever depends on the degree of permanent cardiac damage. Cardiac involvement may resolve completely, especially if it is the first episode and the prophylactic regimen is followed. The severity of cardiac involvement worsens with each recurrence of rheumatic fever. A cardiomyopathy is an intrinsic disease of the heart muscle and is not associated with other forms of heart disease (Table 147-1). There are three types of cardiomyopathy based on anatomic and functional features: 1. 2. 3.


Pediatrics_Nelson

Pediatrics_Nelson. 2. 3. Dilated cardiomyopathies are the most common. They are often idiopathic, but may be due to infection (echovirus or Coxsackie B virus) or be postinfectious, familial, or secondary to systemic disease or to cardiotoxic drugs. Hypertrophic cardiomyopathies are usually familial with autosomal dominant inheritance, but may occur sporadically. Restrictive cardiomyopathies are rare; they may be idiopathic or associated with systemic disease (Table 147-2). Available @ StudentConsult.com


Pediatrics_Nelson

Pediatrics_Nelson. Available @ StudentConsult.com Dilated cardiomyopathies result in enlargement of the leftventricle only or of both ventricles. Myocardial contractility is variably decreased. Children with dilated cardiomyopathy present with signs and symptoms of inadequate cardiac output and heart failure. Tachypnea and tachycardia are present on examination. Peripheral pulses are often weak because of a narrow pulse pressure. Rales may be audible on auscultation. The heart sounds may be muffled, and an S3 is often present. Concurrent infectious illness may result in circulatory collapse and shock in children with dilated cardiomyopathies.


Pediatrics_Nelson

Pediatrics_Nelson. Hypertrophic cardiomyopathy is initially difficult to diagnose. Infants, but not older children, frequently present withsigns of heart failure. Sudden death may be the initial presentation in older children. Dyspnea, fatigue, chest pain,syncope or near-syncope, and palpitations may be present.A murmur is heard in more than 50% of children referred after identification of an affected family member. Restrictive cardiomyopathies are relatively rare in pediatrics. Presentingsymptoms usually include dyspnea exacerbated by a respiratory illness, syncope, hepatomegaly, and an S4 heart sound on examination.


Pediatrics_Nelson

Pediatrics_Nelson. Duchenne muscular dystrophy Other muscular dystrophies (Becker, limb-girdle) Myotonic dystrophy Kearns-Sayre syndrome (progressive external ophthalmoplegia) Carnitine deficiency syndromes Endocardial fibroelastosis Mitochondrial myopathy syndromes Familial dilated cardiomyopathy (dominant, recessive, X-linked) Familial hypertrophic cardiomyopathy Familial restrictive cardiomyopathy Pompe disease (glycogen storage) Viral (e.g., coxsackievirus infection, mumps, Epstein-Barr virus infection, influenza, parainfluenza infection, measles, varicella, HIV infection) Rickettsial (e.g., psittacosis, Coxiella infection, Rocky Mountain spotted fever) Bacterial (e.g., diphtheria, Mycoplasma infection, meningococcal disease, leptospirosis, Lyme disease) Parasitic (e.g., Chagas disease, toxoplasmosis) Hypothyroidism Hyperthyroidism Pheochromocytoma Mitochondrial myopathies and oxidative respiratory chain defects Type II, X-linked 3-methylglutaconic aciduria HIV, Human immunodeficiency virus.


Pediatrics_Nelson

Pediatrics_Nelson. Hypothyroidism Hyperthyroidism Pheochromocytoma Mitochondrial myopathies and oxidative respiratory chain defects Type II, X-linked 3-methylglutaconic aciduria HIV, Human immunodeficiency virus. Etiology Infectious Sporadic Infiltrative (amyloidosis, sarcoidosis) Metabolic Inherited (autosomal dominant) Noninfiltrative (idiopathic, familial) Toxic Storage disease (hemochromatosis, Fabry Idiopathic Available @ StudentConsult.com


Pediatrics_Nelson

Pediatrics_Nelson. Storage disease (hemochromatosis, Fabry Idiopathic Available @ StudentConsult.com Cardiomegaly usually is seen on chest radiographs for all three types of cardiomyopathies. The electrocardiogram (ECG) in dilated cardiomyopathy may have nonspecific ST-T wave changes and left ventricular hypertrophy. ECG evidence of right ventricular hypertrophy is present in 25% of children with cardiomyopathy. The ECG with hypertrophic cardiomyopathy is universally abnormal, but changes are nonspecific. Primary hypertrophic cardiomyopathy is associated with a prolonged QT interval. Children with restrictive cardiomyopathies may show atrial enlargement on the ECG. Echocardiography features vary by type of cardiomyopathy.


Pediatrics_Nelson

Pediatrics_Nelson. Dilated cardiomyopathies result in left atrial and ventricular dilation, a decreased shortening fraction, and globally depressed contractility. Asymmetrical septal hypertrophy and left ventricular outflow tract obstruction are seen in hyper-trophic cardiomyopathies. Massive atrial dilation is seen in restrictive cardiomyopathies. Endomyocardial biopsy specimens, obtained while the patient is hemodynamically stable, identify histologic type and allow tests for mitochondrial or infiltrative diseases. Supportive therapy, including diuretics, inotropic medications, and afterload reduction, is provided for all three types of cardiomyopathy. If a specific etiology can be identified, treatment is directed at the etiology. Symptomatic therapy with close monitoring and follow-up is crucial. Because of the high mortality rate associated with all forms of cardiomyopathy, cardiac transplantation must be considered.


Pediatrics_Nelson

Pediatrics_Nelson. Pericarditis is inflammation of the parietal and visceral surfaces of the pericardium. It is most often viral in origin, with many viruses identified as causative agents. A bacterial etiology is rare but causes a much more serious and symptomatic pericarditis. Staphylococcus aureus and Streptococcus pneumoniae are the most likely bacterial causes. Pericarditis is associated with collagen vascular diseases, such as rheumatoid arthritis, and is seen with uremia (Table 148-1). Postpericardiotomy syndrome is a relatively common form of pericarditis that follows heart surgery. Pneumococcus, meningococcus* Coxsackievirus (group A, B) Echovirus Mumps Influenza Epstein-Barr Cytomegalovirus From Sigman G: Chest pain. In Kliegman RM, Nieder ML, Super DM. editors: Practical Strategies in Pediatric Diagnosis and Therapy, Philadelphia, 1996, WB Saunders. *Infectious or immune complex.


Pediatrics_Nelson

Pediatrics_Nelson. From Sigman G: Chest pain. In Kliegman RM, Nieder ML, Super DM. editors: Practical Strategies in Pediatric Diagnosis and Therapy, Philadelphia, 1996, WB Saunders. *Infectious or immune complex. †Common (viral pericarditis or myopericarditis is probably the most common cause of acute pericarditis in a previously normal host). Chest pain (worsened if lying down or with inspiration) Dyspnea Malaise Patient assumes sitting position Fever Tachycardia Friction rub (accentuated by inspiration, body position) Enlarged heart by percussion and x-ray examination Distant heart sounds As above, plus: Distended neck veins Hepatomegaly Pulsus paradoxus (>10 mm Hg with inspiration) Narrow pulse pressure Weak pulse, poor peripheral perfusion Available @ StudentConsult.com


Pediatrics_Nelson

Pediatrics_Nelson. As above, plus: Distended neck veins Hepatomegaly Pulsus paradoxus (>10 mm Hg with inspiration) Narrow pulse pressure Weak pulse, poor peripheral perfusion Available @ StudentConsult.com The symptoms of pericarditis (Table 148-2) depend on the amount of fluid in the pericardial space and how fast it accumulates. A small effusion usually is well tolerated. A large effusion may be well tolerated if it accumulates slowly. The faster the fluid accumulates, the sooner the patient is hemodynamically compromised and develops symptoms.


Pediatrics_Nelson

Pediatrics_Nelson. Echocardiography is the most specific and useful diagnostictest for detection of pericardial effusions. A chest x-ray mayreveal cardiomegaly. A large effusion creates a rounded, globular cardiac silhouette. The electrocardiogram (ECG) may showtachycardia, elevated ST segments, reduced QRS voltage orelectrical alternans (variable QRS amplitude). The causative organism may be identified through viral titers, antistreptolysin O (ASO) titers, or diagnostic testing of the pericardial fluid. Pericardiocentesis is indicated for treatment of hemodynamically significant effusions and to determine the etiology of the pericarditis. Additional treatment is directed at the specific etiology. There is no specific treatment for viral pericarditis other than antiinflammatory medications. Kliegman RM, Behrman RE, Jenson HB, et al: Nelson Textbook of Pediatrics, ed 19, Philadelphia, 2011, Saunders Lai WW, Mertens LL, Cohen MS, Geva T: Echocardiography in Pediatric and


Pediatrics_Nelson

Pediatrics_Nelson. Kliegman RM, Behrman RE, Jenson HB, et al: Nelson Textbook of Pediatrics, ed 19, Philadelphia, 2011, Saunders Lai WW, Mertens LL, Cohen MS, Geva T: Echocardiography in Pediatric and Congenital Heart Disease: from Fetus to Adult, Oxford, UK, 2009, Blackwell Moller JH, Hoffman JI, Benson DW, Van Hare GF, Wren C: Pediatric Cardio vascular Medicine, ed 2, West Sussex, UK, 2012, Wiley-Blackwell Shaddy RE: Heart Failure in Congenital Heart Disease, London, 2011, Springer Wren C: Concise Guide to Pediatric Arrhythmias, West Sussex, UK, 2012, Julie A. Panepinto, Rowena C. Punzalan, and J. Paul Scott 20 A detailed history of the onset, severity, progression, associated symptoms, presence of systemic complaints, and exacerbating factors is crucial to the diagnosis of a blood disorder. In many blood disorders, a detailed pedigree identifying a pattern of inheritance can point to the diagnosis. Available @ StudentConsult.com


Pediatrics_Nelson

Pediatrics_Nelson. Available @ StudentConsult.com Jaundice Anemia Bleeding Petechiae/Purpura Pancytopenia Failure to Thrive The physical examination of patients with blood disordersfirst focuses on hemodynamic stability. Acute episodes ofanemia may be life-threatening, presenting with impairment of perfusion and cognitive status. The two mostcommon findings of anemia include pallor and jaundice. The presence of petechiae, purpura, or deeper sites of bleeding, including generalized hemorrhage, indicatesabnormalities of platelets, coagulation factors, or both.Growth parameters point to whether anemia is an acuteor chronic process. Severe types of anemia, thrombocytopenia, and pancytopenia often are associated with congenital anomalies and a pattern of growth delay. Organsystem involvement (especially hepatosplenomegaly and lymphadenopathy) or systemic illness point to a generalized illness as the cause for hematologic abnormalities(Table 149-1).


Pediatrics_Nelson

Pediatrics_Nelson. Diagnosis of pediatric blood disorders requires a detailed knowledge of normal hematologic values and varies according to ageand, after puberty, according to sex (Table 149-2). Directed bythe history, physical examination, and screening laboratorystudies, specific diagnostic testing can confirm the diagnosis.


Pediatrics_Nelson

Pediatrics_Nelson. Hematopoiesis begins by 3 weeks of gestation with erythropoiesis in the yolk sac. By 2 months’ gestation, the primary site of hematopoiesis migrates to the liver. By 5 to 6 months’ gestation, the process shifts from the liver to the bone marrow. An extremely premature infant may have significant extramedullary hematopoiesis due to limited bone marrow hematopoiesis. During infancy, virtually all marrow cavities are actively hematopoietic and the proportion of hematopoietic to stromal elements is quite high. As the child grows, hematopoiesis moves to the central bones of the body (vertebrae, sternum, ribs, and pelvis), and the marrow is gradually replaced with fat. Hemolysis or marrow damage may lead to marrow repopulation of cavities where hematopoiesis previously had ceased or may delay the shift of hematopoiesis. Hepatosplenomegaly in patients with chronic hemolysis may signify extramedullary hematopoiesis. When a patient with cytopenia is being evaluated, a bone marrow examination


Pediatrics_Nelson

Pediatrics_Nelson. the shift of hematopoiesis. Hepatosplenomegaly in patients with chronic hemolysis may signify extramedullary hematopoiesis. When a patient with cytopenia is being evaluated, a bone marrow examination provides valuable information about processes that lead to underproduction of circulating cells. In addition, bone marrow infiltration by neoplastic elements or storage cells often occurs in concert with infiltration in the spleen, liver, and lymph nodes.


Pediatrics_Nelson

Pediatrics_Nelson. The hematopoietic cells consist of the following: 1. Small compartment of pluripotential progenitor stem cells that resemble small lymphocytes and are capable of forming all myeloid elements 2. Large compartment of committed, proliferating cells of myeloid, erythroid, and megakaryocytic lineage 3. Large compartment of postmitotic maturing cells(Fig. 149-1) The bone marrow is the major storage organ for mature neutrophils and contains about seven times the intravascular pool of neutrophils. It contains 2.5 to 5 times as many cells of myeloid lineage as cells of erythroid lineage. Smaller numbers of megakaryocytes, plasma cells, histiocytes, lymphocytes, and stromal cells are also stored in the marrow. Erythropoiesis (red blood cell [RBC] production) iscontrolled by erythropoietin, a glycoprotein that stimulatesprimitive pluripotential stem cells to differentiate along the


Pediatrics_Nelson

Pediatrics_Nelson. Figure 149-1 Major cytokine sources and actions to promote hematopoiesis. Cells of the bone marrow microenvironment, such as macrophages, endothelial cells, and reticular fibroblasts, produce macrophage colony-stimulating factor (M-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and granulocyte colony-stimulating factor (G-CSF) after stimulation. For all lineages, optimal development requires a combination of early and late acting factors. BFU, Burst-forming unit; CFU, colony-forming unit; EPO, erythropoietin; IL, interleukin; MSC, myeloid stem cell; PSC, pluripotent stem cell; TNF, tumor necrosis factor; TPO, thrombopoietin. (From Sieff CA, Nathan DG, Clark SC: The anatomy and physiology of hematopoiesis. In Orkin SH, Nathan DG, editors: Hematology of Infancy and Childhood, ed 5, Philadelphia, 1998, WB Saunders, p 168.)


Pediatrics_Nelson

Pediatrics_Nelson. Table 149-1 Presentation of Hematologic Disorders CONDITION SYMPTOMS AND SIGNS COMMON EXAMPLES Anemia Pallor, fatigue, heart failure, jaundice Iron deficiency, hemolytic anemia Polycythemia Irritability, cyanosis, seizures, jaundice, stroke, headache Cyanotic heart disease, infant of diabetic mother, cystic fibrosis Neutropenia Fever, pharyngitis, oral ulceration, cellulitis, Congenital or drug-induced agranulocytosis, leukemia lymphadenopathy, bacteremia, gingivitis Thrombocytopenia Petechiae, ecchymosis, gastrointestinal hemorrhage, ITP, leukemia epistaxis Coagulopathy Bruising, hemarthrosis, mucosal bleeding von Willebrand disease, hemophilia, DIC Thrombosis Pulmonary embolism, deep vein thrombosis Lupus anticoagulant; protein C, protein S, or antithrombin III deficiency; factor V Leiden, prothrombin 20210 DIC, Disseminated intravascular coagulation; ITP, idiopathic thrombocytopenic purpura.


Pediatrics_Nelson

Pediatrics_Nelson. DIC, Disseminated intravascular coagulation; ITP, idiopathic thrombocytopenic purpura. Cord 16.8 13.7–20.1 55 45–65 5 18,000 9000–30,000 61 40–80 31 2 6 7 blood 2 wk 16.5 13–20 50 42–66 1 12,000 5000–21,000 40 3 mo 12.0 9.5–14.5 36 31–41 1 12,000 6000–18,000 30 6 mo–6 12.0 10.5–14 37 33–42 1 10,000 6000–15,000 45 7–12 yr 13.0 11–16 38 34–40 1 8000 4500–13,500 55 Female 14.0 12–16 42 37–47 1.6 7500 5000–10,000 55 35–70 35 3 7 0 Male 16.0 14–18 47 42–52 From Behrman RE, editor: Nelson Textbook of Pediatrics, ed 14, Philadelphia, 1992, WB Saunders. WBCs, White blood cells.


Pediatrics_Nelson

Pediatrics_Nelson. erythroid line and is made by the juxtaglomerular apparatus of the kidney in response to local tissue hypoxia. Thenormally high hemoglobin level of the fetus is a result of fetal erythropoietin production in the liver in response tolow Po2 in utero. Erythropoietin leads to production of theerythroid colony-forming unit. The earliest recognizableerythroid cell is the erythroblast, which forms eight or moredaughter cells. The RBC nucleus becomes gradually pyknotic and eventually is extruded. The cell is then releasedfrom the marrow as a reticulocyte that maintains residual mitochondrial and protein synthetic capacity. Thesehighly specialized RBC precursors are engaged primarily inthe production of globin chains, glycolytic enzymes, and heme. Iron is taken up via transferrin receptors and incorporated into the heme ring, which combines with globinchains synthesized within the immature RBC. When themessenger RNA and mitochondria are gone from the RBC,heme or protein synthesis is no longer


Pediatrics_Nelson

Pediatrics_Nelson. into the heme ring, which combines with globinchains synthesized within the immature RBC. When themessenger RNA and mitochondria are gone from the RBC,heme or protein synthesis is no longer possible; however,the RBC continues to function for its normal life span of about 120 days.


Pediatrics_Nelson

Pediatrics_Nelson. Embryonic hemoglobins are produced during yolk sacerythropoiesis, then replaced by fetal hemoglobin (hemoglobin F, α2γ2) during the hepatic phase. During the thirdtrimester, gamma chain production gradually diminishes,replaced by beta chains, resulting in hemoglobin A (a2β2). Some fetal factors (e.g., infant of a diabetic mother) delayonset of beta chain production, but premature birth doesnot. Just after birth, with rapid increases in oxygen saturation, erythropoietin production stops and, thus, erythropoiesis ceases. Fetal RBCs have a shorter survival time (60days).


Pediatrics_Nelson

Pediatrics_Nelson. During the first few months of postnatal life, rapid growth, shortened RBC survival, and cessation of erythropoiesis cause a gradual decline in hemoglobin levels, with a nadir at 8 to 10 weeks of life. This so-called physiologic nadir is accentuated in premature infants. Erythropoietin is produced in response to the decline in hemoglobin and decreased oxygen delivery. Erythropoiesis subsequently resumes with an increase in the reticulocyte count. The hemoglobin level gradually increases, accompanied by synthesis of increasing amounts of hemoglobin A. By 6 months of age in healthy infants, only trace gamma chain synthesis occurs.


Pediatrics_Nelson

Pediatrics_Nelson. Production of neutrophil precursors is controlled predominantly by two different colony-stimulating factors (seeFig. 149-1). The most immature neutrophil precursors arecontrolled by granulocyte-macrophage colony-stimulating factor (GM-CSF), produced by monocytes and lymphocytes. GM-CSF increases the entry of primitive precursorcells into the myeloid line of differentiation. Granulocyte colony-stimulating factor (G-CSF) augments the production of more mature granulocyte precursors. GM-CSF and G-CSF, working in concert, can augment production of neutrophils, shorten the usual 10to 14-day production timefrom stem cell to mature neutrophil, and stimulate functional activity. The rapid increase in neutrophil count thatoccurs with infection is caused by release of stored neutrophils from the bone marrow, under the control of GM-CSF.During maturation, a mitotic pool of neutrophil precursorsexists—myeloblasts, promyelocytes, and myelocytes possessing primary granules. The postmitotic pool


Pediatrics_Nelson

Pediatrics_Nelson. bone marrow, under the control of GM-CSF.During maturation, a mitotic pool of neutrophil precursorsexists—myeloblasts, promyelocytes, and myelocytes possessing primary granules. The postmitotic pool consists ofmetamyelocytes, bands, and mature polymorphonuclear leukocytes containing secondary or specific granules thatdefine the cell type. Only bands and mature neutrophils arefully functional with regard to phagocytosis, chemotaxis,and bacterial killing. Neutrophils migrate from the bonemarrow, circulate for 6 to 7 hours, and enter the tissues, where they become end-stage cells that do not recirculate.Eosinophil production is under the control of a related glycoprotein hormone, interleukin 3. Eosinophils, which playa role in host defense against parasites, also are capable ofliving in tissues for prolonged periods.


Pediatrics_Nelson

Pediatrics_Nelson. Megakaryocytes are giant, multinucleated cells derivedfrom the primitive stem cell and are polyploid (16 to 32 timesthe normal DNA content) because of nuclear but not cytoplasmic cell division. Platelets form by invagination of themegakaryocytic cell membrane and bud off from the periphery. Thrombopoietin is the primary regulator of plateletproduction. Platelets adhere to damaged endothelium andsubendothelial surfaces via specific receptors for the adhesive proteins, von Willebrand factor (vWF), and fibrinogen.Platelets also have specific granules that readily release theircontents after stimulation and trigger the process of plateletaggregation. Platelets circulate for 7 to 10 days and have nonucleus. Lymphocytes are particularly abundant in the bone marrow of young children. These are primarily B lymphocytes arising in the spleen and lymph nodes, but T lymphocytes also are present.


Pediatrics_Nelson

Pediatrics_Nelson. Lymphocytes are particularly abundant in the bone marrow of young children. These are primarily B lymphocytes arising in the spleen and lymph nodes, but T lymphocytes also are present. The diagnosis of anemia is determined by comparison of thepatient’s hemoglobin level with age-specific and sex-specific normal values (see Table 149-2). The production ofandrogens at the onset of puberty in boys causes males tomaintain a normal hemoglobin value about 1.5 to 2 g/dLhigher than girls. The easiest quantitative definition of anemia is any hemoglobin or hematocrit value that is 2 standard deviations (SDs) (95% confidence limits) below themean for age and gender. However, in certain pathologicstates, anemia may be present with a normal hemoglobinlevel (e.g., cyanotic cardiac or pulmonary disease or abnormally high hemoglobin affinity for oxygen). This is a physiologic definition of anemia. Anemia is often a manifestationof some other primary process and may accentuate otherorgan dysfunction.


Pediatrics_Nelson

Pediatrics_Nelson. Anemias are classified based on the size and hemoglobincontent of the cells (Fig. 150-1). Hypochromic, microcytic anemia is caused by an inadequate production of hemoglobin. The most common causes of this type of anemia are iron deficiency and thalassemia. Most normocytic anemias are associated with a systemic illness that impairs Hypochromic, Microcytic ° major, minor disease Copper deficiency Sideroblastic anemia Aluminum, (?) lead Normochromic, Normocytic • Hemoglobin SS, S-C, S-° thalassemia DIC, HUS, TTP Figure 150-1 Use of the complete blood count, reticulocyte count, and blood smear in the diagnosis of anemia. DIC, Disseminated intra-vascular coagulation; G6PD, glucose-6-phosphate dehydrogenase; HUS, hemolytic uremic syndrome; R/O, rule out; RPI, reticulocyte production index; TTP, thrombotic thrombocytopenic purpura.