65 years old man, implanted with a triple chamber defibrillator Concerto II CRT-D for valvular cardiomyopathy with left bundle branch block; Crosstalk and adjustment of the atrial sensitivity at 0.5 mV; interrogation of the device demonstrating ventricular sensed episodes.
Tracing
Ventricular sensed episode obtained during the initial interrogation of the device;
This tracing illustrates the difficulty of adjusting the atrial sensitivity in CRT patients. This patient has both a VA crosstalk justifying a decrease of the atrial sensitivity, and an atrial detection signal (in sinus rhythm) of small amplitude, warranting an increase of the atrial sensitivity. At rest, the atrial amplitude was measured at 0.8 mV. The crosstalk was permanent with the atrial sensitivity programmed at 0.5 mV. The quality of the atrial detection can be altered with the chest expansion. In patients with preserved atrioventricular conduction, the sudden loss of the atrial detection will result in an interruption of biventricular pacing. In patients with no AV conduction (Pmk dependent patients), the sudden loss of the atrial detection will result in a sharp drop of the heart rate. In this patient, the solution is probably not trying to find a compromise in programming the atrial sensitivity (avoid crosstalk and preserve detection) but to set a high sensitivity (0.3 mV) and trying to avoid crosstalk by extending an absolute post-ventricular atrial blanking period. However, this may reduce the device capacity to detect episodes of atrial arrhythmia.
