The 12 Rhythms of Christmas: Type II AV-Block

This article is the sixth in our latest series, The 12 Rhythms of Christmas, where each day we examine a new rhythm disorder. It’s a continuation of the theme behind last year’s 12 Leads of Christmas. Type II AV-Block Except for first degree,  type II is probably the simplest of the AV-blocks to identify. There’s really only two major criteria: A P-wave suddenly and unexpectedly fails to conduct to the ventricles. The PR-intervals of the P-waves that do conduct are fixed and equal. Let’s examine the ECG below, which exhibits both of those findings. The computer, however, disagrees and suggests and alternate diagnosis. Which of is right? Figure 1. This ECG has P-waves that don’t conduct; is it type II AV-block? The first step in our rhythm analysis is to examine the atrial rate for regularity. Why is that important? Because: The most common cause of a pause is a non-conducted PAC. Non-conducted PAC’s Let’s digress for a moment and examine an ECG that the computer interprets as actually showing type II AV-block. It was obtained on a 33 year old male with a chief complaint of pleuritic chest pain x 3 weeks. Figure 2. Sinus rhythm with frequent non-conducted PAC’s interpreted as type II AV-block by the computer. The first thing you’ll notice on the above ECG is that there are several pauses in the regular sinus rhythm. Close inspection, however, reveals the culprit… Figure 3. Non-conducted PAC’s. There are P-waves burie...
Source: EMS 12-Lead - Category: Cardiology Authors: Tags: 12 Rhythms of Christmas Vince DiGiulio Source Type: research