Second Degree Heart Block Type I ECG Interpretation with Sample Strip

ECG Strip

Second Degree Heart Block Type I ecg rhythm strip

Second Degree Heart Block Type I Rhythm Strip Features

Rate: The underlying rate
Rhythm: Irregular but with progressively longer PR interval lengthening
P Wave: Normal
PR Interval: Progressively longer until a QRS complex is missed, then cycle repeats
QRS: Normal (0.06-0.10 sec)
A prolonging P-R interval from one cardiac complex to the next, until it reaches a point where the QRS complex is non-conducted (blocked or more simply missing). Then the pattern starts over again.
Second degree Heart Block Type I Wenckebach is a condition where the atrioventricular node conducts each successive impulse earlier and earlier. The PQ interval prolongs from beat to beat up until a drop-out of one QRS complex. The following impulse will then be conducted normally and the cycle to begin again. Thus, the presence of second-degree AV block is diagnosed when one or more (but not all) of the atrial impulses fail to conduct to the ventricles.
External Source: http://www.uptodate.com/contents/second-degree-atrioventricular-block-mobitz-type-i-wenckebach-block
UpToDate

Return to ECG Reference Guide Index

Authors and Sources

Authors and Reviewers

ECG heart rhythm modules: Thomas O'Brien.
ECG monitor simulation developer: Steve Collmann
12 Lead Course: Dr. Michael Mazzini, MD.
Spanish language ECG: Breena R. Taira, MD, MPH
Medical review: Dr. Jonathan Keroes, MD
Medical review: Dr. Pedro Azevedo, MD, Cardiology
Last Update: 11/8/2021

Sources

Electrocardiography for Healthcare Professionals, 6th Edition Kathryn Booth and Thomas O'Brien
ISBN10: 1265013470, ISBN13: 9781265013479
McGraw Hill, 2023
Rapid Interpretation of EKG's, Sixth Edition
Dale Dublin
Cover Publishing Company
EKG Reference Guide
EKG.Academy
12 Lead EKG for Nurses: Simple Steps to Interpret Rhythms, Arrhythmias, Blocks, Hypertrophy, Infarcts, & Cardiac Drugs
Aaron Reed
Create Space Independent Publishing
Heart Sounds and Murmurs: A Practical Guide with Audio CD-ROM 3rd Edition
Elsevier-Health Sciences Division
Barbara A. Erickson, PhD, RN, CCRN
The Virtual Cardiac Patient: A Multimedia Guide to Heart Sounds, Murmurs, EKG Jonathan Keroes, David Lieberman
Publisher: Lippincott Williams & Wilkin)
ISBN-10: 0781784425; ISBN-13: 978-0781784429
Project Semilla, UCLA Emergency Medicine, EKG Training Breena R. Taira, MD, MPH
ECG Reference Guide
PracticalClinicalSkills.com