Crosstalk and ventricular oversensing

Patient

65 years old man, implanted with a triple chamber defibrillator Concerto II CRT-D for ischemic cardiomyoaphty with complete AV bloc and episodes of atrial arrhythmias; Implanted with a true bipolar ventricular lead in the interventricular septum; Several episodes of dizziness;

Trace

Tracing

Episodes of ventricular sensed event in the device memory;

possible atrial arrhythmia and biventricular pacing ;
spontaneous atrial and ventricular rhythm (with a 1/1 ratio and synchronous atrium and ventricle) ;
recovery of biventricular pacing ;

Episodes of non-sustained VT in the device memory;

diagnosis of non sustained VT;
atrial arrhythmia and biventricular pacing; paced ventricular event are detected in the atrium (V/A crosstalk) ; We can also identify on the ventricular channel a small amplitude signal (non detected) preceding the atrial signals ;
probable A/V crosstalk with detection of the atrial signal by the ventricular channel and inhibition of biventricular pacing resulting in a pause of 2 to 3 seconds ; the atrial component that was present before but not detected at the ventricular level, is now detected ; these are noted TS (in the VT zone) ;
recovery of biventricular pacing;

During this consultation, the complete interrogation of the device was performed with a programmed sensitivity of 0.5 mV ;

EGM1 : Atrial EGM, EGM2 : Ventricular EGM (bipolar channel), EGM3 : Ventricular EGM (far-field channel)

atrial arrhythmia and biventricular pacing;
modification of the programming (Increase of the ventricular sensitivity at 0.3 mV) ;
A/V crosstalk ; Ventricular oversensing of the atrial activity during respiratory movements (breath) ; ventricular pause (false diagnosis of non-sustained VT) ;
biventricular pacing recovery ;
programming of a sensitivity at 0.5 mV ;
atrial arrhythmia and biventricular pacing ;
activation of the algorithm of response to sensed event and of a ventricular sensitivity of 0.3mV ;
ventricular oversensing occurring during a deep breath but no pause because the biventricular pacing response to a detected ventricular event is activated (VVT) ; markers are difficult to see because they are superimposed (fusion of VS and BV) ; this type of particular stimulation is limited in frequency ; However the device is less sensitive after a stimulation than after a sensed event. Accordingly, the first signals following the ventricular pacing are not detected (detection occur at the end of the cycle when the sensitivity is maximal), which explain a limited frequency of intervention.
end of oversensing;
new episode of ventricular oversensing due to respiratory movements;

Comments

This pacemaker-dependent patient had multiple episodes of presyncope related to a crosstalk of an atrial arrhythmia to the ventricular channel, inducing inappropriate inhibition of the ventricular stimulation and prolonged asystole. This ventricular oversensing of the atrial signal varied with the respiratory cycles, appearing only during inhalation, which explained the brief duration of the pauses and the relatively modest symptoms.

There is no post atrial-sensed ventricular blanking period that can protect against this type of ventricular oversensing. In addition, the atrial signal was first seen by the ventricular channel then by the atrial channel, which precludes the effectiveness of such a blanking period.

Both options should be preferred in this context: 1) reposition the right ventricular lead; in this patient the lead was positioned on the high inter-ventricular septum (No lead displacement seen on the chest X-ray); 2) find a compromise for the device programming; the first option would be to reprogram the RV detection in integrated bipolar (ventricular sensing between the coil and the tip electrode); In this case, this option did not allow to suppress the atrial oversensing; A second option would be to program the response to a detected ventricular sensed event option. As demonstrated in this case, this option allowed to avoid pacing inhibition without suppressing the atrial oversensing; A third option would be to reduce ventricular sensitivity to avoid the atrial oversensing. However, this would be associated with an increased risk of undersensing true ventricular arrhythmias; In this patient, reprogramming the ventricular sensitivity at 0.6 mV has eliminated these episodes of oversensing; Induction of a FV was performed to verify the accurate detection of the ventricular arrhythmia despite the alteration of the ventricular sensitivity.

Pacing & Defibrillation

ECG

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