The 12 Rhythms of Christmas: First Degree AV-Block

This article is the fourth in our latest series, The 12 Rhythms of Christmas, where each day we examine a new rhythm disorder. It is a continuation of the theme behind last year’s 12 Leads of Christmas. An 84 year old male presents with a chief complaint of abdominal pain. The ECG below is performed: Figure 1. What is the rhythm? What is the rhythm? You may think the title of this article gives the answer away but, as we learned in the series’ first post on sinus tachycardia, the obvious can fool you when we’re dealing with ECG’s. Let’s walk through it step by step. There are regular P-waves of normal polarity at about 60 bpm Though they look like rounded U-waves in several leads (I, II, V5, V5), they are sharply peaked in V1–V4, confirming them as P-waves. U-waves will never come to a point like this. There are regular, narrow (suprventricular) QRS complexes at a rate of approximately 60 bpm. There is a 1:1 ratio between the P-waves and QRS-complexes. And that’s all we know for certain at this point. The first step to dissecting tricky rhythms is to accept as fact only those things that we can state objectively. Never assume a relationship between complexes unless there is convincing evidence for it. Why is that important? At this point in our analysis the large distance between the P-waves and QRS-compelxes raises doubts that the two are even connected! That leaves us three major rhythm diagnoses in play: Sinus rhythm with marked firs...
Source: EMS 12-Lead - Category: Cardiology Authors: Tags: 12 Rhythms of Christmas Vince DiGiulio Source Type: research