Echo/Doppler evaluation of hemodynamics after aortic valve replacement: principles of interrogation and evaluation of high gradients.

Echocardiography/Doppler is the standard clinical tool for the assessment of hemodynamics after aortic valve replacement. Analysis can include mean and peak transvalvular gradients, dimensionless valve index, effective orifice area from the continuity equation, geometric orifice area from planimetry, and energy loss coefficient. High gradients after aortic valve replacement can be, but are not necessarily, caused by left ventricular outflow obstruction; and not all left ventricular outflow obstruction after aortic valve replacement is due to prosthesis dysfunction. Understanding the methods by which echocardiography and Doppler are used to noninvasively assess aortic valve hemodynamics, and the caveats associated with those methods, can help the clinician distinguish obstructive from nonobstructive causes of high gradients, and prosthesis dysfunction from other causes of obstruction.