Left Bundle Branch Block Case Studies

Home » MEDCLIN530 » EKG » 12-Lead EKG Confidence » IV. EKG Changes Related to Conduction Abnormalities » 12. Left Bundle Branch Block » Left Bundle Branch Block Case Studies
Headshot of Kevin Hodges, Vice Chair, Emergency Medicine
Kevin Hodges
Vice Chair, Emergency Medicine
envelope icon phone icon
Headshot of Chris Anderson, Vice Chair, Pediatrics
Chris Anderson
Vice Chair, Pediatrics
envelope icon
Table of Contents

Case 1: Left bundle branch block

Tap the arrow to view the case.
This is an example of LBBB. It meets the two criteria for diagnosis. First, the QRS interval is 0.12 seconds or more. This means the ventricles were not depolarized simultaneously, but sequentially. Since the ventricles are out of sequence, inspection of the last half of the QRS identifies the late or delayed ventricle. In Figure 12.12, the end of the QRS is positive in lead I (an R wave), and so points to the patient's left. The end of the QRS in lead V1 is negative, and so points posteriorly and leftward. In both leads I and V1, the delayed part of the QRS points to the left ventricle. Since the left ventricle is delayed, it must be the left bundle that is blocked.

Image credits

Unless otherwise noted, images are from Adobe Stock.

Warning: Copyright restrictions

This course content and all writings and materials provided to you at the Elson S. Floyd College of Medicine are protected by federal copyright law and Washington State University policy. The content is copyrighted by the Washington State University Board of Regents or licensed to the Elson S. Floyd College of Medicine by the copyright owner. Limited access to this content is given for personal academic study and review purposes of registered students and faculty of Elson S. Floyd College of Medicine. You shall not otherwise copy, share, distribute, modify, transmit, upload, post, republish, reuse, sell, gift, rent, lend or otherwise disseminate any portion of this course content without permission in writing, signed by an individual authorized by Washington State University.

 

The Digital Publishing team makes every effort to ensure these educational materials are accessible to all learners. If you run into problems, please contact us with your concerns at medicine.digipub@wsu.edu. We will respond within 2 business days.

Site Menu