Loss of biventricular capture secondary to an episode of noise on the right ventricular lead
Patient
61 years old man implanted with a triple chamber defibrillator Viva XT CRT-D for ischemic cardiomyopathy with a wide QRS ; interrogation of the device with the recording of several episode of non sustained VT;
Trace
Plots
- atrio-ventricular rhythm ;
- acceleration of the ventricular rhythm with very short cycles close to the ventricular blanking limit and extremely short cycles of a few dozen of ms ;
- regularization of the ventricular rhythm ;
- novel episode of acceleration of the ventricular rate;
Tracing
- atrial stimulation and biventricular pacing (AP-BV) ;
- very fast ventricular signal detected at the limit of the ventricular blanking (120 ms) within the FV zone (FS), inhibiting the biventricular stimulation ;
- detection of a signal in the safety window, triggering a ventricular safety pacing at the end of the safety window (110 ms), with very short VS-VP cycles corresponding to the shortest cycle represented on the plot.
- interruption of the oversensing and recovery of a biventricular stimulation ;
- oversensing restarts;
Comments
This tracing corresponds to the oversensing by the right ventricular lead of a 50 Hz signal emitted by a poorly insulated electric saw. This noise temporarily inhibits the biventricular stimulation. This type of episode may be symptomatic in a pacemaker dependent patient (which is not the case of this patient) by inducing a more or less prolonged ventricular pause. As for the previous tracing, treatment consists in recognizing the emitting source to prevent recurrences.
