Diastolic murmurs include aortic and pulmonic regurgitation (early diastolic), and mitral or tricuspid stenosis (mid-late diastolic).
Tricuspid stenosis is very rare and is discussed further in the valvular heart disease section.
Aortic regurgitation (AR)
The murmur of aortic regurgitation is a soft, high-pitched, early diastolic decrescendo murmur usually heard best at the third intercostal space on the left (Erb's point) at end expiration while the patient is sitting up and leaning forward. If the aortic regurgitation is due to aortic root disease, the murmur is best heard at the right upper sternal border and not at Erb's point. As aortic regurgitation worsens in severity, the pressure between the left ventricle and the aorta equalize much faster, thus the murmur becomes significantly shorter.
In people with aortic regurgitation, an early diastolic rumble may also be heard at the apex due to the regurgitant jet striking the anterior leaflet of the mitral valve causing it to vibrate. This murmur is termed the Austin-Flint murmur.
In addition to the above two murmurs, a systolic ejection murmur may be present in people with severe aortic regurgitation at the right upper sternal border, simply due to the large stroke volume passing through the aortic valve with each systolic contraction of the LV.
Pulmonic regurgitation (PR)
Pulmonic regurgitation produces a murmur that is often indistinguishable from that of aortic regurgitation. Pulmonic regurgitation produces a soft, high-pitched, early diastolic decrescendo murmur heard best at the pulmonic listening post (LUSB). The murmur of pulmonic regurgitation increases in intensity during inspiration, unlike that of aortic regurgitation. The murmur of pulmonic regurgitation is classically referred to as the "Graham-Steell murmur" after it's initial describers.
Mitral stenosis results in a uniquely shaped, low-pitched diastolic murmur best heard at the cardiac apex. The opening of the mitral valve produces an "opening snap" due to the high left atrial pressures, which is immediately followed by a decrescendo murmur as blood flows passively from the left atrium to the left ventricle through the stenosed mitral valve, creating turbulence. Immediately before the S1 sound, active left ventricular filling occurs when the left atrium contracts and forces more blood through the stenosed mitral valve, creating a late diastolic crescendo murmur. In the presence of atrial fibrillation, the active left ventricular filling phase does not take place and the latter part of the mitral stenosis murmur disappears.
As mitral stenosis worsens, left atrial pressure increases forcing the mitral valve open earlier in diastole. Thus, in severe mitral stenosis, the opening snap occurs earlier as does the initial decrescendo part of the murmur. The opening snap and murmur of mitral stenosis also respond to dynamic auscultation.
The murmur of a patent ductus arteriosus is continuous throughout systole and diastole. Often the S2 heart sound is difficult to detect. The murmur begins just after S1 and crescendos, peaks at S2, then decrescendos to S1.
Summary of Diastolic Murmurs