third heart sound (S3), S3 gallop

Etiology

• normal in children & in pregnant women
• after the age of 30-35, an S3 indicates
  • left ventricular failure
  • volume overload on the left ventricle
    • aortic regurgitation
    • mitral regurgitation
    • cardiomyopathy
  • pulmonary hypertension*

* S3 gallop best heard at the left sternal border with the patient supine

* right-sided gallops best heard with the patient supine

* left-sided gallops best heard with patient in left lateral decubitus position

Pathology

• probably caused by tensing of the chordae tendinae as blood distends the left ventricle during diastole

Clinical manifestations

• low-pitched sound following S2, heard best with the bell of the stethoscope at the apex of the heart

Management

• avoid beta-blockers & calcium channel blockers in patients with decompensated heart failure