split first (1st) heart sound
The differential contraction of the left and right ventricle causes a splitting of the first heart sound.
An abnormally large splitting of the first heart sound is heard when there are:
- either conduction abnormalities:
- right bundle branch block
- pacing from an electrode on the LV
- left ventricular ectopics
- or mechanical causes:
- Ebsteins anomaly
- atrial septal defect
- tricuspid stenosis
- Kirby B (1993).Clinical examination of the heart. Medicine International, 21(8), 294-99.
Last reviewed 01/2018