57-year-old woman with pulmonary arterial hypertension under anticoagulant and amiodarone therapy for episodes of paroxysmal AF, implanted with a dual-chamber pacemaker for episodes of syncope due to paroxysmal atrioventricular conduction disorder; hospitalization for cardiac decompensation with palpitations since 2 weeks.
Tracing 31a: the first line corresponds to lead I with the superimposed markers, the second line to the atrial EGM and the last line to the ventricular EGM;
Tracing 31b: pacemaker interrogation shows that the blanked flutter search algorithm is deprogrammed; programming of this algorithm;
Tracing 31c: the 12-lead electrocardiogram is indicative of a common flutter;
Tracing 31d: the patient underwent a well conducted anticoagulant treatment; attempted termination by rapid pacing of the atrium with the aid of the pacemaker;
Tracing 31e: renewed attempt at termination;
The initial absence of fallback on this episode of undiagnosed flutter was hence responsible for a prolonged rapid ventricular pacing favoring cardiac decompensation. Indeed, this patient experienced palpitations for almost 2 weeks, day and night. The programming of the blanked flutter search algorithm allowed terminating this inappropriate pacing and the return to a more acceptable ventricular conduction rate. The attempt to terminate this arrhythmia could only be achieved because the effective anticoagulation conditions were met (INR > 2 for more than 3 weeks). Pacing above the flutter rate proved ineffective. Acceleration of the pacing did not allow a return to sinus rhythm although degraded the arrhythmia into atrial fibrillation. This patient showed spontaneous termination a few minutes after pacing. It is common that, once installed, an atrial flutter can persist for long periods of time. An attempt at termination can lead to immediate success with a return to sinus rhythm but also to a more delayed success with, in the first stage, a transformation of the arrhythmia into AF followed secondly by termination.
The blanked flutter algorithm is no longer present on the new dual-chamber pacemaker platforms. Indeed, as explained previously, it is now possible to program the blanking to partial or partial + which enables atrial sensing in this phase following ventricular pacing and which considerably limits the risk of not sensing 1 out of 2 atrial activities. However, regardless of the programming, there is an absolute blanking of 30 ms to avoid sensing of the pacing spike (very limited risk that an atrial activity is contemporaneous with this spike).
