Final answer:
The Valsalva maneuver increases the murmur intensity of left ventricular outflow tract obstruction, commonly seen in hypertrophic cardiomyopathy, by reducing left ventricular volume and increasing outflow tract obstruction.
Step-by-step explanation:
The Valsalva maneuver has a specific effect on the murmur caused by left ventricular outflow tract obstruction (LVOTO) often due to hypertrophic cardiomyopathy (HCM). During the maneuver, intrathoracic pressure increases, reducing venous return to the heart and consequently decreasing ventricular filling. This results in a decrease in the left ventricular volume, which in turn increases the obstruction in the outflow tract, leading to the intensification of the murmur associated with LVOTO. Clinically, heart sounds related to heart murmurs and blood flow can often be auscultated using a stethoscope to detect the 'lub' and 'dub' sounds, which correspond to the closing of the atrioventricular valves and semilunar valves, respectively. The Valsalva maneuver is one of several actions that can modulate heart murmurs, evidencing the pathological enlargement of the heart or other cardiac anomalies.