There are a few common extra heart sounds that the clinician may encounter. These include ejection sounds that occur with pulmonic or AS heard in early systole, “clicks” that are heard in mitral or tricuspid valve prolapse occurring later in systole, as well as “snaps,” “knocks” and “plops.”
Systolic ejection click: A systolic ejection click frequently indicates a bicuspid aortic valve. This sound is heard just after the S1 heart sound. Usually, the opening of the aortic valve is not audible; however, with a bicuspid aortic valve, the leaflets dome suddenly prior to opening and create a systolic ejection click. The click may be difficult to hear in the presence of significant AS.
Mitral valve prolapse click: Mitral valve prolapse produces a mid systolic click, usually followed by a uniform, high-pitched murmur. The murmur is actually due to MR that accompanies the MVP; thus, it is heard best at the cardiac apex. MVP responds to dynamic auscultation. After sudden standing, preload is decreased, and the click moves earlier in systole. With sudden squatting, preload increases, and the click moves later in systole.
Opening snap: In the setting of MS, the increased left atrial opening pressures cause an opening snap to occur when the mitral valve leaflets suddenly tense and dome into the LV in early diastole. This high-frequency sound is best heard at the apex.
Tumor plop: A tumor plop is an early diastolic low-pitched sound just after the S2 heart sound. This is in contrast to the opening snap of rheumatic mitral valve stenosis, which is high pitched. A tumor plop may be followed by a low-pitched diastolic murmur. If the mitral valve inflow obstruction is significant enough, physical exam findings of congestive HF will be present.
Pericardial knock: A pericardial knock can be present in patients with constrictive pericarditis, as the early filling of the LV is limited from the constrictive process. The knock occurs earlier than a S3 heart sound. which is the distinguishing factor; this is because the S3 heart sound occurs from a stretch of a very compliant LV, which takes a short time longer.