47 year old man implanted with a triple chamber defibrillator Viva XT in the context of an idiopathic dilated cardiomyopathy with left bundle branch block; 3 months post implant, good clinical response, Device interrogation and identification of episodes of ventricular sense.
On the recorded tracings of ventricular sense in the device memories, we find the atrial and ventricular markers but no electrograms;
This tracing demonstrates the interest to analyze carefully the episodes of ventricular sensing stored in the device memory. This patient has a left bundle branch block but does not present a major atrioventricular conduction disorder (the PR interval of 190 ms at rest and 170 ms at peak exercise). Programming a spontaneous AV delay at150 ms at rest with rate adaptive AV delay of 110 ms at peak exercise ensures a good biventricular capture up to the upper tracking rate. The tracing shows that the recorded rate displayed by the patient exceeds the upper tracking rate (sinus tachycardia). In a patient in complete atrioventricular block, this would result in a Wenckebach operation. In this patient with a preserved atrioventricular conduction, no ventricular pacing being possible beyond the upper tracking rate, the AV delay gradually lengthens before the spontaneous conduction reappears with the loss of biventricular pacing at peak exercise. An increase of the upper tracking rate to 140 bpm has eliminated this type of episodes.
