Loss of biventricular pacing due to crosstalk

Patient

68 years old man implanted with a triple chamber defibrillator Viva XT CRT-D for dilated cardiomyopathy with atypical bundle branch block ; routine follow-up ; reduction of the percentage of biventricular pacing.

Trace

Episodes of ventricular sensed event in the device memory;

3 consecutive cycle AR-VS ;
commutation (MS : mode switch) to DDD mode with recovery of the atrial synchronism ;
alternation of AS-BV-Ab cycles ; probable V/A crosstalk ;
commutation to DDIR (MS) ;
asynchronous mode (DDIR) with no AV delay after an atrial sensed event; spontaneous ventricular events (VS) ;

Recording of an episode of AT/AF in the device memories ;

on the plot, typical aspect in rail (alternation of 2 different atrial frequencies) compatible with a crosstalk ;
probable crosstalk following the spontaneous ventricular depolarization ; Fixed AR-VS-Ab sequence, except for some cycles with a very short VS-Ab interval ;
intermittent interruption of the crosstalk ;
commutation to a synchronous mode (MS), exit form mode switch;
crosstalk restart ;
diagnosis of AF and commutation to DDIR mode ;
absence biventricular stimulation (spontaneous ventricular events) ;
diagnosis of AF made by the device for a duration of 20 seconds ; Tracing recorded during the consultation;
biventricular stimulation and crosstalk, the ventricular signal being detected by the atrial channel in the PVARP (AR) ;
decrease of the atrial sensitivity (from 0.3 to 0.6 mV) ;
crosstalk disappearing ;

Comments

Defibrillator memories were saturated by short episodes of misdiagnosed atrial arrhythmia related to crosstalk. The atrial detection following a ventricular pacing has been changed in the new ICD platforms with 3 programming possibilities of post ventricular atrial blanking: the absolute blanking period corresponding to a traditional blanking (no marker), a partial blanking and a partial + blanking period (marker Ab). A signal detected in this blanking period does not trigger AV delay but is counted for the analysis of the atrial rhythm (for the discrimination process) and for the mode switch algorithm. This new blanking period is associated with an increased risk of inappropriate commutation of mode due to VA crosstalk. The recorded electrograms must be systematically analyzed to confirm the diagnosis made by the device. In this patient, repeated episodes of false AF were responsible for a significant decrease in the percentage of biventricular pacing. Programming a partial blanking + (with a reduction of the atrial sensitivity at the beginning of ventricular cycle) did not suppress the crosstalk. However, reprogramming of the constant atrial sensitivity 0.6 mV was effective.

Pacing & Defibrillation

ECG

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