Search
second heart sound (S2)
Occurs following the T wave on EKG & reflects closing of the aortic valve & pulmonic valves.
The aortic valve heart sound A2 generally precedes the pulmonic valve heart sound P2 (splitting of S2) & splitting increases with inspiration.
Also see aortic valve heart sound (A2) & pulmonic valve heart sound (P2).
Causes of widened splitting:
1) occurs normally with inspiration
2) occurs in conditions that delay right ventricular ejection
3) right bundle branch block
4) pulmonic stenosis
5) pulmonary hypertension [4]
6) mitral regurgitation
7) left to right shunt [4]
- ventricular septal defect
- atrial septal defect
Fixed splitting (no changes with inspiration)
- atrial septal defect
- severe pulmonic stenosis with fixed right ventricular output [4]
Paradoxical splitting (splitting narrows with inspiration)
1) occurs with conditions that prolong LV ejection
2) aortic stenosis
3) left bundle branch block
4) congestive heart failure (CHF)
5) acute coronary syndrome with LV dysfunction [4]
6) left ventricular hypertrophy
- hypertrophic cardiomyopathy
7) due to:
a) delayed closure of aortic valve
b) A2 occurring subsequent to P2
At a rate of about 120 beats/second, systole & diastole become indistinguishable by auscultation & S1 must be distinguished from S2 from the timing of the carotid or apical impulse, both which occur in early systole, immediately after S1.
Specific
aortic valve heart sound (A2)
pulmonic valve heart sound (P2)
General
heart sound(s)
References
- Harrison's Principles of Internal Medicine, 13th ed.
Companion Handbook, Isselbacher et al (eds), McGraw-Hill
Inc. NY, 1995, pg 327
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 38
- Guide to Physical Examination & History Taking, 6th edition,
Bates B, JB Lippincott, Philadelphia, 1995, pg 283-85
- Medical Knowledge Self Assessment Program (MKSAP) 14, 18.
American College of Physicians, Philadelphia 2006, 2018.