Which statement best describes the mechanism of a heart murmur?

Which statement best describes the mechanism of a heart murmur?

• A. The valve does not close completely, allowing backflow into the chamber it just left.
• B. Blockage of a coronary artery due to atherosclerosis.
• C. The heart pumps too slowly.
• D. An enlarged heart pressing on the lungs.

Answer: (A)

Heart murmurs come from turbulent blood flow, which usually results from abnormal valve function. The mechanism described as the valve not closing completely, allowing backflow into the chamber it just left, is the classic cause of regurgitant murmurs. When a valve fails to seal, blood leaks backward during the heart’s cycle, and the ensuing chaotic flow creates the audible sound we recognize as a murmur. This backflow and turbulence can occur with different valves and can be accompanied by a murmur heard in systole or diastole, depending on the timing of the regurgitation. Other scenarios don’t explain the murmur mechanism. Blockage of a coronary artery causes ischemia and chest pain, not a murmur from valvular flow. A slow heart rate changes rhythm and output but doesn’t inherently create turbulent flow through a valve. An enlarged heart can cause symptoms and structural changes, but the heart sound associated with a murmur is specifically due to abnormal valve closure and resultant turbulence, not simply size or rate of the heart.

Heart murmurs come from turbulent blood flow, which usually results from abnormal valve function. The mechanism described as the valve not closing completely, allowing backflow into the chamber it just left, is the classic cause of regurgitant murmurs. When a valve fails to seal, blood leaks backward during the heart’s cycle, and the ensuing chaotic flow creates the audible sound we recognize as a murmur. This backflow and turbulence can occur with different valves and can be accompanied by a murmur heard in systole or diastole, depending on the timing of the regurgitation.

Other scenarios don’t explain the murmur mechanism. Blockage of a coronary artery causes ischemia and chest pain, not a murmur from valvular flow. A slow heart rate changes rhythm and output but doesn’t inherently create turbulent flow through a valve. An enlarged heart can cause symptoms and structural changes, but the heart sound associated with a murmur is specifically due to abnormal valve closure and resultant turbulence, not simply size or rate of the heart.