Ventricular detection during exercise

Tracing N° 1
Medtronic Devices: CRT Field: Effort

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.  

Graph and trace

On the recorded tracings of ventricular sense in the device memories, we find the atrial and ventricular markers but no electrograms;

  1. Fast sinus rhythm at the upper tracking rate (460 ms, 130 bpm) biventricular stimulation (AS-BV) ;
  2. Atrial rate above the upper tracking rate, spontaneous conducted ventricule (AS-VS) and loss of biventricular stimulation ;

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.


Theoritical features / Basic concepts

Rate-Responsive Pacing Maximal tracking rate AV-delay optimization during exercise Atrial sensitivity Ventricular extrasystole in patients with a long PR interval   In a resynchronized patient, the main objectives of the programming during exercise are: to maintain a permanent and effective biventricular capture for high heart rates, to ensure a good contribution of atrial systole to cardiac output, and to allow for appropriate heart rate acceleration which is the fundamental adaptive mechanism of the cardiac output during exercise, in particular in heart failure patients. Checking for the maintenance of a permanent biventricular capture during exercise must be part of the standard CRT patient assessment. The recording of episodes of ventricular sensing occurring at high sinus rate in...