In hypertrophic obstructive cardiomyopathy, which maneuver increases the murmur intensity?

In hypertrophic obstructive cardiomyopathy, which maneuver increases the murmur intensity?

• A. Squatting decreases murmur
• B. Valsalva maneuver increases murmur
• C. Handgrip increases murmur
• D. Standing from squatting lowers the murmur

Answer: (B)

The murmur in hypertrophic obstructive cardiomyopathy changes with preload, afterload, and contractility because the obstruction in the left ventricular outflow tract becomes more severe when the ventricle is smaller and the flow is more hyperdynamic. The Valsalva maneuver reduces venous return (preload) and, during the strain phase, tends to increase sympathetic drive and contractility. With less preload, the left ventricular cavity is smaller, narrowing the LVOT even more and intensifying the dynamic obstruction, which makes the murmur louder. In contrast, squatting increases preload and afterload, which expands the LV cavity and reduces the obstruction, softening the murmur. Handgrip raises afterload, which also tends to lessen the obstruction and reduce murmur intensity. Standing up from a squat reduces preload and typically increases the murmur, not decreases it.

The murmur in hypertrophic obstructive cardiomyopathy changes with preload, afterload, and contractility because the obstruction in the left ventricular outflow tract becomes more severe when the ventricle is smaller and the flow is more hyperdynamic. The Valsalva maneuver reduces venous return (preload) and, during the strain phase, tends to increase sympathetic drive and contractility. With less preload, the left ventricular cavity is smaller, narrowing the LVOT even more and intensifying the dynamic obstruction, which makes the murmur louder.

In contrast, squatting increases preload and afterload, which expands the LV cavity and reduces the obstruction, softening the murmur. Handgrip raises afterload, which also tends to lessen the obstruction and reduce murmur intensity. Standing up from a squat reduces preload and typically increases the murmur, not decreases it.