Which murmur is pandiastolic and loudest in early diastole?

• A. Aortic regurgitation
• B. Mitral stenosis
• C. Tricuspid regurgitation
• D. Pulmonary regurgitation

Answer: (A)

The main idea is that aortic regurgitation causes backward flow from the aorta into the left ventricle during diastole. Because the gradient between aortic pressure (which is relatively high) and LV diastolic pressure (which remains low early in diastole and rises as the ventricle fills) persists throughout most of diastole, the regurgitant flow can produce a murmur that is heard across the entire diastolic period (pandiastolic). It is loudest early in diastole because that’s when the pressure gradient is greatest right after S2, so the regurgitant jet is strongest at the start and then diminishes as diastole progresses and LV pressure rises. This murmur is typically a high-pitched, blowing, decrescendo murmur best heard along the left sternal border, and it often becomes louder with increased afterload (for example, with handgrip).

In contrast, other diastolic murmurs have different timing and characteristics (for instance, mitral stenosis is a diastolic rumble that’s more prominent later in diastole, and tricuspid regurgitation is a systolic murmur; pulmonary regurgitation is diastolic but often described with a different auscultation window). The combination of pandiastolic timing with loud early diastolic peak points to aortic regurgitation.