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Second Degree Heart Block Type II | Reference Guide

ecg rhythm strip for reference guide


EKG Features

Rate: Characterized by Atrial rate usually faster than ventricular rate (usually slow)
Rhythm: Regular (atrial) and irregular (ventricular)
P Wave: Normal form, but more P waves than QRS complexes
PR Interval: Normal or prolonged
QRS: Normal or wide
A constant P-R interval with missing QRS complexes. Occurring in a specific pattern in a ratio with the P waves.
Second degree Heart Block Mobitz II is characterized by intermittently non-conducted P waves which are not preceded by PR prolongation and are not followed by PR shortening. Mobitz II is usually caused by conduction failure/delay of the His-Purkinje system. In three out of four cases, this conduction block is located distal to the Bundle of His, creating wide QRS complexes. In the other 25% of cases, the block is located within the Bundle of His, producing narrower QRS complexes.
External Source: http://http://texasheart.org/HIC/Topics/Cond/bbblock.cfm
Texas Heart Institute
Second Degree Heart Block Type II - Reference Guide

Authors and Reviewers

Authored by Thomas O Brien
. Medically reviewed by Dr. Jonathan Keroes, MD
Last Update: 11/8/2021



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