Heart Sounds

Normal heart sounds

S1 is “slurred” or very slightly split and S2 (at the apex) is single as the pulmonic component (P2) is not audible at the apex but should be searched for in the left third interspace (looking for physiologic splitting)

Normal splitting of the first heart sound

S1 is “slurred” indicating its two components, the mitral valve closure sound which occurs first and the tricuspid valve closure sound which follows. This is of no clinical consequence but it should be distinguished from other sounds which occur very close to S1 such as an S4 gallop, early ejection sound, pacemaker sounds and others.

Widely split first heart sound

Whenever the right ventricle’s activation is delayed, S1 is widely split. The most frequent cause of wide splitting of S1 is right bundle branch block. Some other causes are idioventricular rhythm from the left ventricle, left ventricle ectopic beats and left ventricular pacing.

Physiologic splitting of the second heart sound

Physiologic splitting of S2

Listen carefully to the second heart sound. You will notice that the second heart sound gradually and progressively splits into two sounds and then slowly reverses the process to become one sound. This is physiologic splitting of the second heart sound and is cyclical as it is due to the inspiratory/expiratory breathing cycle.

Clearly heard splitting of the second heart sound implies a normal cardiac ejection fraction.

After age 50, or so, splitting of the second heart sound occurs much less frequently and its absence is not necessarily abnormal.

Mitral regurgitation, an example of a systolic flat murmur

Midsystolic flat murmur of mitral regurgitation

The murmur is “flat” in the sense that it maintains the same pitch and “shape” throughout. Many would call this a “holosystolic” murmur.

Aortic stenosis, an example of a crescendo-decrescendo murmur

Aortic stenosis murmur

Aortic stenosis. Example of an ejection or crescendo/decrescendo murmur. Also known as a diamond shaped murmur. In this case, the severity of the aortic stenosis is mild as the murmur peaks in early systole.

Aortic insufficiency, an example of a decrescendo diastolic murmur

Aortic insufficiency murmur

A diastolic, decrescendo, blowing murmur.

Improving detection of an aortic insufficiency murmur: Position – sitting up and leaning forward. Lying in bed on the stethoscope in the left upper sternal border. Having the patient hold his or her breath after full exhalation.

Aortic insufficiency due to a valvular vs. aortic root problem suggested by the location of the loudest murmur (Best heard over the right 2^nd ICS suggests an aortic cause whereas if best heard in the left 2^nd ICS suggests an aortic valve cause).