Third heart sound

A low-frequency, brief, early diastolic ventricular sound caused by rapid passive ventricular filling, best heard with the bell of the stethoscope at the cardiac apex

Causes

• Physiological causes

  • Children and young adults

  • High-output states: Anemia or thyrotoxicosis

  • Trained athletes

  • Pregnancy

• Pathological cardiac causes

  • Heart failure (especially systolic heart failure)

  • Dilated cardiomyopathy

  • Valvular heart disease

  • Restrictive cardiomyopathy

  • Pericarditis

  • Left-to-right cardiac shunts

• Volume overload states