The patient’s symptoms improved with rate-responsive permanent ventricular pacing, and restoration of sinus rhythm was not attempted based on patient preference.Of occlusion of central retinal vein History of paroxysmal atrial tachycardia History of paroxysmal. Entrainment from the cavotricsupid isthmus resulted in a long postpacing interval indicating that the flutter was not typical. Ventricular escape rhythms would not be preceded by His bundle electrograms, and low His/bundle-branch sites of escape rhythm would show a short HV interval. The escape rhythm was preceded by a His bundle electrogram and normal His bundle to ventricle (HV) interval, indicating a junctional escape from the atrioventricular node or upper His bundle. An electrophysiology study was also undertaken where CHB was noted, again from the dissociation between the constant atrial rhythm and constant ventricular rhythm ( Figure 4). He underwent permanent pacemaker implantation first for symptomatic bradycardia. Identifying the absence of atrioventricular conduction from the presenting surface ECG was important in the decision-making process for the patient. A indicates atrium AVN, atrioventricular node H, His bundle and V, ventricle. Note the variable flutter wave to QRS interval with complete heart block. C, Atrial flutter with complete heart block and junctional escape. However, clinically, when atrial and ventricular rhythms are regular, one can simply interrogate the interval between the QRS complexes and preceding flutter wave. The ladder diagram is an oversimplification because it is not possible to determine which flutter wave is actually conducted to the ventricle. Note the consistent flutter wave (F) to QRS interval. B, The corresponding ladder diagram of atrioventricular conduction.
A, Atrial flutter with a constant 5:1 atrioventricular conduction. An accelerated junctional or ventricular rhythm can lead to atrioventricular dissociation without CHB during AFL or sinus rhythm and should be considered when the ventricular rate is relatively high.įigure 3. Here, the dissociation of flutter and QRS complexes will be evident when a longer rhythm strip is examined. An exception to this rule would be isorhythmic dissociation of the flutter and ventricular rhythms. 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.
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