first heart sound (S1)
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Introduction
Occurs immediately following the QRS complex on EKG & reflects closing of the mitral valve & tricuspid valve. 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.
Loud S1:
- mitral stenosis
- short PR interval
- thin chest wall
Soft S1:
- long PR interval
- heart failure
- mitral regurgitation
- heavily calcified mitral valve
- thick chest wall
- pulmonary emphysema
More general terms
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