Complete AE-Adult-Echocardiography ARDMS Materials

The Doppler signal shown is a continuous wave (CW) Doppler tracing typical of measuring high velocity flow, such as an intracavitary gradient in the left ventricle, often seen in hypertrophic obstructive cardiomyopathy (HOCM). CW Doppler is needed to capture the highest velocity flow across the entire ventricular cavity and outflow tract.

Pulsed wave Doppler has limited spatial resolution and cannot measure high velocities without aliasing; thus, it is less useful for localizing gradients in this context. Pulsed wave at mitral leaflet tips is used for mitral inflow assessment, not intracavitary gradients.

This approach is recommended in ASE guidelines for cardiomyopathy and valvular obstruction evaluation【12:ASE Doppler Guidelines†p.120-125】【16:Textbook of Clinical Echocardiography, 6e†p.350-355】

Comprehensive and Detailed Explanation From Exact Extract:

Mitral regurgitation (MR) Doppler signals tend to be longer in duration because MR occurs throughout systole, often spanning most or all of ventricular systole, resulting in a prolonged jet on continuous wave Doppler.

Aortic stenosis (AS) velocities can be high but may vary and are not necessarily always higher than MR velocities. The density of waveforms is not a reliable discriminator. MR only happens in systole, not diastole, which makes option C incorrect.

Therefore, the duration or length of the Doppler signal (longer for MR) is the best differentiating feature.

This differentiation is explained in the "Textbook of Clinical Echocardiography, 6e", Chapter on Doppler Assessment of Valvular Disease【20:320-325†Textbook of Clinical Echocardiography】.

Severe mitral regurgitation (MR) is typically characterized by significant left atrial dilation due to volume overload, and systolic flow reversal in the pulmonary veins caused by retrograde flow from the left ventricle into the left atrium during systole.

An eccentric mitral regurgitant jet is common in severe MR, often due to leaflet prolapse or flail, resulting in directed jets that hug the atrial wall.

Mitral regurgitant jet velocity, however, is usually significantly higher in severe MR due to the high pressure gradient between the left ventricle and left atrium during systole. A jet velocity less than 0.5 cm/sec is extremely low and inconsistent with severe MR. Typically, MR jet velocities are in the range of several meters per second.

Thus, a mitral regurgitant jet velocity less than 0.5 cm/sec is NOT associated with severe MR.

This is detailed in echocardiography literature discussing MR quantification and Doppler findings, emphasizing high-velocity regurgitant jets in severe MR and hemodynamic consequences seen on pulmonary vein flow and LA size .

During dobutamine stress testing, a normal physiological response includes increased myocardial contractility leading to a decrease in left ventricular (LV) cavity size during systole due to more effective ejection. Concurrently, systolic blood pressure increases due to the inotropic and chronotropic effects of dobutamine.

An increase in LV cavity size during stress would suggest impaired contractility or ischemia, which is abnormal.

This normal response is detailed in the "Textbook of Clinical Echocardiography, 6e", Chapter on Stress Echocardiography and Hemodynamic Responses【20:400-405†Textbook of Clinical Echocardiography】.