ECG Guru - Instructor Resources

A gathering place for instructors of ECG and cardiac topics.

       

Subscribe to me on YouTube

Welcome to the ECG GURU

Serving ECG instructors and their students since 2011.
Download ECGs, Illustrations, and other Resources for your classes!

 

Featured App

Instructors Collection ECG of the Week: Left Bundle Branch Block With Left Ventricular Hypertrophy

Tue, 09/20/2016 - 23:14 -- Dawn

This 92-year-old patient was diagnosed with left bundle branch block on ECG, and left ventricular hypertrophy on echocardiogram.  The two conditions are very often seen together, in fact, a majority of LBBB patients have LVH.  Since the two conditions can have similar ECG changes, it is difficult from the ECG alone to determine the presence of LVH when LBBB is present.  If the ECG criteria for LVH are present, it can be assumed that LVH is present, even in the presence of LBBB.  For determining LVH by ECG criteria, the Sokolov-Lyon criteria are commonly used ( S wave in V1 + R wave in V5 or V6 > 35 mm). 

The common criteria for left bundle branch block include:  wide QRS complex, frontal plane axis normal or leftward, negative QRS in V1, and positive QRS in leads I and V6.   LBBB is only found in supraventricular rhythms (not ventricular rhythms).  The ST segment and T wave will be negative in leads with positive QRS complexes, and positive in leads with negative QRSs (discordant).

Left ventricular hypertrophy also widens the QRS, although not often as much as LBBB does.  There will be discordant ST segments and T waves, which is called the "strain" pattern.  It also is easier to diagnose in supraventricular rhythms, because ventricular rhythms usually have large QRS complexes due to the depolarization wave being in one direction across the heart.

For confirmation of LVH, an echocardiogram is recommended.

This ECG also has an interesting rhythm.  The first beat appears normal, the second beat is a PAC.  The third beat appears to arise from a different focus, which would make it an escape beat, but it is very difficult to determine this due to the very tiny P waves.  After a pause, a regular sinus rhythm resumes.  To see the P waves, look at the right chest leads:  V1, V2, V3.  Since left bundle branch block only occurs in SUPRAVENTRICULAR rhythms, it is important to determine the rhythm, and P waves are a definite sign of SV rhythm.  We wish the P waves here were taller.

References:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC482258/http://www.ncbi.nlm.nih.gov/pmc/articles/PMC482000/, http://journal.publications.chestnet.org/article.aspx?articleid=1058580, http://lifeinthefastlane.com/ecg-library/basics/left-ventricular-hypertrophy/

Ventricular Systole

Click to open: 
Ventricular systole

This is an original illustration by Dawn Altman. It may be used free of charge for enhancement of classroom teaching materials. For commercial publication, please contact the artist at [email protected] 

ECG Basics: Second-degree AV Block With Characteristics of Type I and Type II

Thu, 09/01/2016 - 11:51 -- Dawn

This strip shows a second-degree AV block.  During most of the strip, 2:1 conduction is present.  At the beginning, however, two consecutive p waves are conducted, revealing progressive prolongation of the PR interval.  This usually represents a Type I , or nodal, block:  progressive refractoriness of the AV node.   However, the wide QRS ( possibly left bundle branch block), and the fact that the non-conducted p waves are "out in the open" where they should have conducted, points to Type II - an intermittant tri-fascicular block. Wenckebach periods in patients with LBBB can be caused by progressive conduction delay in the right bundle branch.

ECG Guru Ads - Products and Services of Interest to our Members

 If you would like to place ads for products or services of interest to our readers, please contact us at Dawn...@gmail.com

 

1924:  Willem Einthoven wins the Nobel prize for inventing the electrocardiograph.

All our content is FREE & COPYRIGHT FREE for non-commercial use

Please be courteous and leave any watermark or author attribution on content you reproduce.

Subscribe to ECG Guru - Instructor Resources RSS