When you hear an extra heart sound that is not a murmur, what are the possible causes of that sound? How do you determine what it is?

Common “extra” heart sounds are:

• well-heard physiological splitting of S2;

• pathological splitting of S2;

• early systolic ejection clicks (aortic ejection sound or ejection click);

• midsystolic clicks;

• opening snap;

• S3; and/or

• S4.

In order to determine the nature of the extra sound you must assess:

• The point of maximum intensity of the sound and its radiation.

• The timing of the sound: Is it in early, mid or late systole? Is it in early, mid or late diastole?

• The quality of the sound: Is it high-pitched (best heard with the diaphragm) or low-pitched (best heard with the bell)?

4. Associated findings. For example, what positional changes affect the sound? Are there associated murmurs? Is there cardiomegaly?

What are the characteristics of physiological or pathological splitting of S2?

Splitting of the second sound, whether physiological or pathological, is best heard over the pulmonic area in the second interspace just to the left of the sternal border or in the third interspace just below the pulmonic area (see diagram at right).

In the presence of pulmonary hypertension or an increased pulmonary flow, splitting may be heard in more distant locations, such as over the left lower parasternal region or even over the apex. However, even if splitting of S2 is heard in such distant locations, it will be loudest around the pulmonic area.

The quality of the sound of a split S2 is high-pitched and is best heard with the diaphragm. The timing of the sound is, of course, intimately related to the second sound.

What are the characteristics of an early systolic ejection click, and what is the clinical significance of this sound?

An early systolic ejection click is a frequently heard sound, usually originating from the aortic valve. If an early aortic ejection click is heard in a young individual, the cause might be a bicuspid aortic valve. Bicuspid aortic valves are quite a common congenital anomaly. In older individuals, early aortic ejection clicks are usually associated with rigid valves. Rigid aortic valves may result from aortic stenosis or from dilatation of the aortic root, as often occurs in old age or in hypertension (the dilated root stretches the valves taut). An aortic ejection click may be heard anywhere in the more broadly defined aortic area (i.e., over the band extending from the left second interspace to the apex). It is often loudest at the apex (diagram at right).

An aortic ejection click is high-pitched and often clicking in quality; it is best heard with the diaphragm. As its name implies, the sound occurs early in systole and it may be considered as one—and, for that matter, the most common—cause of a split S1.

What are the characteristics of midsystolic clicks? What is the clinical significance?

One or more midsystolic clicks are characteristic of mitral valve prolapse. They may or may not be associated with a mid or late systolic murmur. Conversely, in some patients with mitral valve prolapse, a murmur may be heard in the absence of clicks.

As its name implies, a midsystolic click is usually heard in midsystole, although in the sitting position it may move to early systole. A midsystolic click is best heard at the apex or just medial to the apex. It is high-pitched and best heard with the diaphragm (see diagram above). A midsystolic click or midsystolic clicks may be made louder by having the patient sit or stand, or by having them perform a Valsalva manoeuvre.

Next issue: More on extra systolic and diastolic sounds.