Which combination of maneuvers will increase murmur intensity in a patient with hypertrophic obstructive cardiomyopathy (HOCM)?

In hypertrophic obstructive cardiomyopathy (HOCM), certain maneuvers can significantly influence the intensity of the associated murmurs due to the dynamic nature of the left ventricular outflow tract (LVOT) obstruction.

When assessing the effects of different maneuvers, it is important to understand how they alter preload and afterload. Standing and values related to preload, such as the volume of blood returning to the heart, can change the intensity of the murmur.

In the case of HOCM, standing leads to a decrease in venous return, resulting in decreased preload. This decreases the size of the left ventricle, further narrowing the outflow tract and increasing the intensity of the murmur. This phenomenon occurs because the decreased blood volume exacerbates the obstruction through the left ventricle outflow tract, thus increasing the velocity of flow and consequently the intensity of the murmur that is generated.

Therefore, decreased preload coupled with the standing position leads to an increase in murmur intensity due to its unique hemodynamic characteristics in patients with HOCM.