Originally Posted by dr-ahmed
Why patients with hypertrophic cardiomyopathy would have crescendo-decrescendo murmur ? and why would it be increased with Valsalva maneuver ?
In hypertrophic cardiomyopathy, a decrease in left ventricular outflow size is associated with an increase in the intensity of the ejection systolic murmur. Remember that this patients have a dynamic outflow obstruction, usually due to systolic anterior motion (SAM) of the anterior leaflet of the mitral valve.
So, with a valsalva maneuver -> decreases preload -> decreased filling of the left ventricle -> increase in LVOT obstruction.
Audible murmurs and Valsalva maneuver