AFL has remarkably constant cycle lengths, as do junctional/ventricular escape rhythms this allows for a quick determination of presence or absence of atrioventricular conduction on the surface ECG by applying the aforementioned principles. Mathematically, if flutter waves are regular and QRS intervals are regular, they must keep a constant relationship when atrioventricular conduction is present and no relationship when conduction is absent as shown in the ladder diagrams ( Figure 3). The ECG was obtained from a different patient to show the constant flutter to QRS complex intervals when atrioventricular conduction is present in contrast to the presenting rhythm shown in Figure 1. The lead II rhythm strip at the bottom shows a fixed flutter wave to QRS interval, indicating the presence of atrioventricular conduction. ECG with atrial flutter and constant 5:1 atrioventricular (AV) conduction. The ventricular rates are similar, but the constant intervals between the QRS complexes and preceding flutter waves indicate that the flutter waves conduct to the QRS complexes, verifying atrioventricular conduction is present.įigure 2. For comparison, an ECG of a different patient with AFL and 5:1 atrioventricular conduction with regular QRS intervals is shown in Figure 2. The right bundle-branch block and left posterior fascicular block noted on the presenting ECG can alert the clinician to cardiac conduction system disease, although it does not indicate CHB. When the atrial and ventricular rhythms are regular, a varying relationship between the 2 indicates dissociation of the 2 rhythms and CHB. 1 The patient’s presenting ECG ( figure 1) shows regular flutter waves and regular QRS complexes but with varying intervals from flutter wave to QRS complex. Customer Service and Ordering InformationĪ slow regular ventricular rhythm during AFL raises the question of whether it is AFL with fixed atrioventricular conduction or AFL with underlying complete heart block (CHB) and a junctional/ventricular escape rhythm.Stroke: Vascular and Interventional Neurology. Journal of the American Heart Association (JAHA).Circ: Cardiovascular Quality & Outcomes. Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).
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