How can you distinguish between aortic stenosis and hypertrophic obstructive cardiomyopathy during a Valsalva maneuver?

In the context of distinguishing between aortic stenosis and hypertrophic obstructive cardiomyopathy (HOCM) during a Valsalva maneuver, recognizing how each condition responds is crucial. During the Valsalva maneuver, which involves forced expiration against a closed airway, there is a decrease in preload due to reduced venous return to the heart.

In aortic stenosis, the left ventricular outflow tract is already narrowed, which naturally leads to a decreased stroke volume when preload is reduced by the Valsalva maneuver. Consequently, you would observe a decrease in the intensity of the systolic ejection murmur associated with aortic stenosis as the outflow is further compromised by the reduced blood volume.

On the other hand, hypertrophic obstructive cardiomyopathy is characterized by a hypertrophied septum that can obstruct the outflow tract, particularly during states of reduced preload. During the Valsalva maneuver, the decreased venous return exacerbates this obstruction, resulting in an increase in the outflow tract gradient, and thus the murmur associated with HOCM becomes louder.

This nuanced understanding of hemodynamics during the Valsalva maneuver provides the basis for correctly identifying the behaviors of these conditions. A