wide split second (2nd) heart sound

Last reviewed 01/2023

The second heart sound is widely split if there is an early A2 or if the P2 is delayed.

• Early A2 can occur in mitral regurgitation or ventricular septal defect. There is a shortening of left ventricular systole because of diminished resistance to left ventricular ejection.
• Delayed P2 - possible causes include :-
• right bundle branch block, where there is delay in the activation of the right ventricle
• pulmonary stenosis - the P2 is soft and delayed;
• atrial septal defect with left to right shunt - there is an increase in right ventricular stroke volume which causes a delayed P2
• prolonged right ventricular contraction as a result of right ventricular failure.