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UR Medicine / Neurosurgery / For Patients / Treatments / Merci Retrieval


Merci Retrieval


What is it?

The Merci device is a tool your doctor may use to help treat a recent stroke. A stroke occurs when the blood supply to part of the brain is suddenly interrupted. Brain cells rely on a constant blood supply, so interrupting this supply, even for a few minutes, can lead to permanent brain damage.

Symptoms of a stroke appear suddenly. Watch for these symptoms:

  • Sudden confusion, trouble talking, or understanding speech
  • Sudden trouble seeing in one or both eyes
  • Sudden severe headache with no known cause

If you or someone you know is experiencing any of these symptoms, do not wait. Call 911 immediately. Time is of the essence.

What is its goal?

Most strokes are caused by a blockage of one of the brain’s blood vessels. In certain situations, if the stroke is diagnosed quickly enough, doctors have a variety of tools that may be able to remove this blockage and return blood flow to the brain. This can sometimes reverse stroke symptoms, or other times make the symptoms less severe than they would have otherwise been.

How is it done?

If there is concern that a patient may have suffered a stroke, the patient is quickly brought to the Emergency Department. Detailed imaging studies (CT or MRI scans) are performed to determine if the patient is a candidate for treatment. If it is felt the patient may gain benefit from the Merci device, they are brought to a specially equipped room called an angiography suite. There, doctors insert a small catheter, or tube, through blood vessels towards the blocked vessel within the brain. The catheter is carefully snaked through the clot. Next, the catheter is slowly pulled back to expose a wire contained within the catheter. As the wire is released, it forms a corkscrew shape. The wire is then slowly pulled back, trapping the clot. Once the clot is trapped within the wire, it can be retrieved from the body and blood flow is restored.

What are the risks?

As with any disease of the brain, the decision to undergo treatment for stroke requires a careful consideration of possible benefits versus risks. Stroke treatments can limit the damage to brain tissue that has not yet died, but come with their own risks. Risks of using the Merci device include bleeding at the site of entry into the body, bleeding within the brain, and causing more damage to the brain. There is no easy formula that can allow physicians and their patients to reach a decision on the best course of therapy—all therapeutic decisions must be made on a case-by-case basis.

What is the success rate?

A patient may undergo Merci retrieval within eight hours of their stroke, but not all patients are candidates. In patients who undergo the procedure, the clot causing the stroke can be removed approximately 50% of the time. A patient’s prognosis depends on how much brain damage has occurred by the time the clot is removed, but patients who have their clot removed generally do better than those who don’t.

How long will I stay in the hospital?

Length of hospitalization will largely depend on the severity of a patient’s stroke. Typically, patients can expect to recover quickly from the procedure, but may stay in the hospital so doctors can treat effects from the stroke. The total amount of time will vary from patient to patient.

What makes URMC special?
