Which physical findings are characteristic of first-degree atrioventricular (AV) block?

Updated: Jan 06, 2020
  • Author: Jamshid Alaeddini, MD, FACC, FHRS; Chief Editor: Jose M Dizon, MD  more...
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No findings on the physical examination are specifically associated with first-degree AV block; it is generally an incidental finding noted on an electrocardiogram (ECG).

The intensity of the first heart sound (S1) is decreased in patients with first-degree AV block. Patients with first-degree AV block may have a short, soft, blowing, diastolic murmur heard at the cardiac apex. This diastolic murmur is not caused by diastolic mitral regurgitation, because it reaches its peak before the onset of regurgitation. The diastolic murmur is thought to be related to antegrade flow through closing mitral valve leaflets that are stiffer than normal. [26] Administration of atropine may reduce the duration of this murmur by shortening the PR interval.

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