Additional heart sounds

Additional heart sounds

Clicks: Clicks may be divided into ejection and non-ejection clicks. The click of mitral valve prolapse is a non-ejection click. It is typically mid systolic. Ejection clicks are heard in aortic and pulmonary stenosis. Vascular ejection clicks may be heard when the aorta or pulmonary artery is dilated. There is one view that ejection clicks should be called ejection sounds. Ejection clicks are early systolic. Aortic ejection click does not move with respiration and hence it is a non-phasic ejection click. Pulmonary ejection click moves away from first heart sound in expiration and is called a phasic ejection click. Pulmonary ejection click becomes closer to the first heart sound as the severity of pulmonary stenosis increases. It is the only right sided event which becomes more prominent in expiration. The phasic nature is due to changes in the pulmonary hang out interval. Hang out interval is the time delay for closure of the pulmonary valve after the crossover of the pulmonary and right ventricular pressure tracings. Longer hang out interval of the pulmonary valve than the aortic valve is due to the lower resistance of the pulmonary circulation. A phasic aortic ejection click may be heard in tetralogy of Fallot. It is a vascular ejection click due to the dilated aorta which receives blood from both ventricles.

Opening snap: Opening snap (OS) is typically heard in mitral stenosis, though it may be there in tricuspid stenosis, though seldom appreciated. Opening snap is a sharp, high pitched sound, heard better with the diaphragm of the stethoscope. It is heard best slightly medial to the apex rather than the at the apex. It occurs after the S2 and is earlier in severe mitral stenosis. Hence S2-OS interval is inversely related to severity of mitral stenosis. Opening snap disappears when the valve becomes non pliable with severe calcification. The mid diastolic murmur of mitral stenosis starts immediately after the opening snap.

Tumor plop: Tumor plop occurs soon after the second sound when a pedunculated atrial myxoma (right or left) pops into the tricuspid or mitral orifice in early diastole.

Pericardial knock: Pericardial knock is an early diastolic sound heard in constrictive pericarditis. It is also called and ‘early S3’. The sudden rush of blood flow from the atria to the ventricles is halted soon by the thickened pericardium which causes restraint for ventricular relaxation, leading to pericardial knock.

Pericardial rub: Pericardial rub is a superficial scratchy sound which is better heard with the person leaning forward. Intensity increases when the diaphragm is pressed on the chest wall. It persists on breath holding and is synchronous with the heart beats, differentiating it from the pleural rub. Pericardial rub is triphasic, with one phase each in systole, diastole and atrial systole. All phases may not be heard always and it is well known to be evanescent.