Alternating Narrow and Wide Complex Tachycardia:

Abstract

Case PresentationA 38-year-old man presented with a 20 year history of repeated episodes of paroxysmal palpitations, terminating spontaneously or with verapamil. Clinical examination and 12-lead electrocardiography (ECG) during sinus rhythm were normal, and echocardiography showed a structurally normal heart. The patient was referred for electrophysiological study and radiofrequency ablation (RFA). During electrophysiological study, tachycardia was induced; the ECG (leads I and V 1 ) is shown in top panel of Figure 1. What is the best explanation for this rhythm? CommentaryThe bottom panel of Figure 1 shows narrow QRS tachycardia recorded just before the top panel of Figure 1. The initial part of tracing of the top panel of Figure 1 shows a narrow QRS tachycardia with cycle length of 325 ms that transitions to a wide QRS tachycardia with right bundle branch block morphology and cycle length of 320 ms. The wide QRS tachycardia then changes again to narFigure 1. (Top panel) Surface leads I and V 1 depict transition from a narrow to right bundle branch block with inferior axis QRS complex tachycardia, and back to narrow complex tachycardia. Note the variable fusion beats of narrow and wide complex tachycardia (beats 4,5, and 10). (Bottom panel) Surface leads I and V 1 depict a segment of more pure narrow QRS tachycardia recorded just before the top panel of Figure 1.row QRS tachycardia in the last part of the tracing, and only the last beat shows entirely narrow QRS. The clinical tachycardia of this patient always showed a right bundle branch block with inferior axis pattern. At electrophysiological study, three multipolar catheters were positioned via the right and left femoral veins at the high right atrium, right ventricle, and the His-bundle region, and another was positioned in the coronary sinus via the right internal jugular vein. Atrial premature stimulation at baseline did not reveal dual atrioventricular (AV) nodal physiology. The narrow QRS tachycardia was induced with right atrial and right ventricular premature stimuli (Figure 2 A). A His bundle depolarization preceded each tachycardia beat with an HV interval of 46 ms, and 1:1 ventriculoatrial (VA) conduction was present with the site of earliest retrograde conduction located at the distal coronary sinus. An identical retrograde activation pattern was present during right ventricular pacing without decremental retrograde conduction. The mechanism of this tachycardia was confirmed to be AV reentrant tachycardia (AVRT) based on the fact that the retrograde earliest atrial electrogram was recorded at the left lateral wall and because of the absence of dual AV nodal pathway physiology, with induction of tachycardia upon reaching a critical AH delay. On multiple occasions, tachycardia converted from a narrow to wide QRS morphology, or vice versa. An example of this transformation is 246

Coexistent Idiopathic Left Ventricular Tachycardia and Atrial Fibrillation Induced by Maintained VA Conduction during Ventricular Tachycardia

“…The present case was the first report demonstrating the coincidence of ILVT and AF. Coexistences of ILVT and SVT, such as AVNRT and AVRT, have been reported 1–3 . A previous report described that dual AV nodal pathways were more prevalent in patients with ILVT than in patients with structural heart disease undergoing catheter ablation of ventricular tachycardia (70% vs 27%, P < 0.001), and the incidence of AVNRT was more frequent in patients with ILVT than that in patients without ILVT (21% vs 1%, P = 0.002) 4 .…”

“…Idiopathic left ventricular tachycardia (ILVT) is a verapamil‐sensitive intrafascicular ventricular tachycardia characterized by the right bundle branch block (RBBB) morphology with left or northwest axis deviation, which can be treated with radiofrequency catheter ablation effectively. Coexistence of ILVT and supraventricular tachycardias (SVTs), such as atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) have been reported previously 1–3 . However, simultaneous occurrence of ILVT and atrial fibrillation (AF) has never been reported.…”

“…Coexistence of ILVT and supraventricular tachycardias (SVTs), such as atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) have been reported previously. [1][2][3] However, simultaneous occurrence of ILVT and atrial fibrillation (AF) has never been reported. We present the case of a patient with double tachycardia of ILVT and AF in which AF was induced by maintained ventriculoatrial (VA) conduction during ILVT.…”