Right Bundle Branch Block Case Studies

Home » MEDCLIN530 » EKG » 12-Lead EKG Confidence » IV. EKG Changes Related to Conduction Abnormalities » 11. Right Bundle Branch Block » Right 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: Right bundle branch block

Tap the arrow to view the case.
This is an example of the simple case of RBBB. 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 in sequence. Since the ventricles are out of sequence, inspection of the last half of the QRS identifies the late or delayed ventricle. In Figure 11.13, the end of the QRS in lead I is an S wave, and so points rightward. The end of the QRS in lead V1 is positive, and so points anteriorly and rightward. In both leads I and V1, the delayed part of the QRS points to the right ventricle. Since the right ventricle is delayed, it must be the right bundle that is blocked.

Case 2: Right bundle branch block with hemiblock

Tap the arrow to view the case.
This is an example of RBBB with associated hemiblock. First, the QRS interval is 0.12 seconds or more. This is the diagnostic hallmark of bundle branch block. 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 again identifies the late or delayed ventricle. In Figure 11.14, the end of the QRS in lead I is an S wave, and so points rightward. The end of the QRS in lead V1 is positive, and so points anteriorly and rightward. In both leads I and V1, the delayed part of the QRS points to the right ventricle. Since the right ventricle is delayed, it must be the right bundle that is blocked.
Remember, only the end of the QRS is used to diagnose bundle branch block. To determine if hemiblock is also present, the entire QRS is evaluated and visualized to determine its direction. Right bundle branch block does not alter the overall direction of the QRS, which should still be pointing inferiorly and to the patient’s left side. In this example the whole QRS points upward (since it is negative in leads II, III, and AVF—mathematically it is—75 degrees). Therefore, the EKG in Figure 11.14 has LAHB as well. The same criteria apply for diagnosing hemiblock whether or not RBBB is present. Always check for the presence of hemiblock when RBBB is detected.

Case 3: Right bundle branch block with anterior infarction

Tap the arrow to view the case.
RBBB can be associated with infarction of the anterior wall (see Chapter 15). The criteria for RBBB remain unaffected by the presence of infarction or hemiblock. First, the QRS interval in Figure 11.15 is 0.12 seconds or more. This is the diagnostic hallmark of bundle branch block. Again, 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 again identifies the late or delayed ventricle.
In Figure 11.15, the end of the QRS in lead I is an S wave, and so points rightward. The end of the QRS in lead V1 is positive, and so points anteriorly and rightward. In both leads I and V1 the delayed part of the QRS points to the right ventricle. Since the right ventricle is delayed, it must be the right bundle that is blocked. Using a step-by-step approach, the diagnosis of RBBB in the presence of infarction or hemiblock is straightforward.

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