ANSWER 1: D. The patient has a subaortic membrane. The images illustrate the importance of thorough interrogation of the area of the left ventricular outflow tract (LVOT) and implementing use of color Doppler. Figure 36-1 does not visualize any aortic valve disease or a membrane. Figure 36-2 demonstrates color aliasing in the LVOT, suggesting high-velocity flow. No mitral regurgitation is seen. On zoom images with the transducer slightly angulated (Figs. 36-3 and 36-4), the membrane is visualized. Additional Doppler images shown in Figures 36-5 and 36-6 confirmed a fixed (nondynamic) gradient consistent with moderate obstruction at rest. There was only minimal aortic regurgitation. A stress echocardiogram may demonstrate increased gradient correlating with the patient’s symptoms during stress.