Because of this, medications such as beta-blockers can lengthen the PR interval and result in a first-degree AV block. Also, a longer PR interval can cause the first heart sound (S1) to sound soft ...

A PR interval consistently longer than 0.20 seconds (greater than 5 small boxes) indicates a first-degree AV block. Note: There is a 1:1 ratio between P waves and QRS complexes, unlike 2nd degree ...

"First-degree Fetal Heart Block May Be Reversible." ScienceDaily. www.sciencedaily.com / releases / 2007 / 02 / 070210170613.htm (accessed May 8, 2025). Explore More ...

The primary categories include first-degree heart block, characterised by a prolonged PR interval but generally considered benign; second-degree heart block, which is further divided into Type I ...

First-degree heart block: This is when the signals slow down. ... Mobitz type I causes a progressive prolongation of the PR interval, which eventually builds to a non-conducting P wave.

To search for sequence variants that modulate heart rate, PR interval and QRS ... S. et al. Long-term outcomes in individuals with prolonged PR interval or first-degree atrioventricular block ...

There are three main types of heart block, and depending on the type, symptoms and treatment vary. First-degree heart block is the mildest type and often requires no treatment.

Type II second-degree AV block. According to the definitions codified by the WHO and the American College of Cardiology (ACC) (both in 1978),13 14 type II second-degree AV block should be defined as ...