 The viewpoint of the echocardiogram may distort the true diameter of the LVOT in some patients.For verification purposes of the obtained valve area using echocardiogram and doppler measures, especially if the obtained valve area is in the range requiring surgery and cardiac output is low, the Gold standard of left heart catheterization for true hemodynamics should be obtained for validation using the Gorlin formula, so patient does not go for unneeded surgery.The Gorlin equation states that the aortic valve area is equal to the flow through the aortic valve during ventricular systole divided by the systolic pressure gradient across the valve times a constant.