In hypertrophic obstructive cardiomyopathy, which statement describes the murmur?

In hypertrophic obstructive cardiomyopathy, which statement describes the murmur?

• A. It intensifies with Valsalva
• B. It diminishes with Valsalva
• C. It is a diastolic murmur
• D. It is best heard with inspiration

Answer: (A)

In hypertrophic obstructive cardiomyopathy, the murmur is a dynamic systolic outflow tract (LVOT) murmur that becomes louder when preload is reduced. During Valsalva, venous return drops and the left ventricular cavity size shrinks, increasing the degree of LVOT obstruction from the hypertrophied septum and systolic anterior motion of the mitral valve. That greater obstruction amplifies the murmur. Conversely, things that raise preload or afterload—like squatting, leg elevation, or handgrip—lessen the obstruction and soften the murmur. It is not a diastolic murmur, and it is not specifically best heard with inspiration (inspiration more relates to right‑sided murmurs).

In hypertrophic obstructive cardiomyopathy, the murmur is a dynamic systolic outflow tract (LVOT) murmur that becomes louder when preload is reduced. During Valsalva, venous return drops and the left ventricular cavity size shrinks, increasing the degree of LVOT obstruction from the hypertrophied septum and systolic anterior motion of the mitral valve. That greater obstruction amplifies the murmur. Conversely, things that raise preload or afterload—like squatting, leg elevation, or handgrip—lessen the obstruction and soften the murmur. It is not a diastolic murmur, and it is not specifically best heard with inspiration (inspiration more relates to right‑sided murmurs).