Atrial flutter and atrioventricular conduction disorder

N° 5
78-year-old man with arterial hypertension and fatigue;
Atrial flutter and atrioventricular conduction disorder

This patient presented an atrial flutter and a high-grade atrioventricular conduction disorder, which is characterized by a slow ventricular rate and a lack of direct relationship between atrial activities and ventricular activities. The highlighting of a second-degree AV block after return to sinus rhythm confirms the presence of this likely junctional conduction disorder (Wenckebach periods with a significant increment in PR interval suggesting a nodal block). This patient was not under any treatment aimed at slowing atrioventricular conduction. The electrical pattern evolved toward an escalation of the conduction disorder with 2:1 atrioventricular rhythm and symptomatic bradycardia of 30 beats/minute. The patient therefore underwent implantation of a dual-chamber pacemaker.

A second-degree AV block type 1 corresponds in the majority of instances to a conduction disorder located in the atrioventricular node and to an exaggeration of decremental conduction. This location explains the predominantly normal morphology of the QRS complexes. Electrophysiological study hence reveals a gradual prolongation of the AH interval, followed by a blocked atrial activity but not followed by a His potential (supra-Hisian block).
Atrial flutter and atrioventricular conduction disorder