Causes of impaired biventricular pacing in cardiac resynchronization devices with left ventricular sensing

Clinical use of CRT-D devices with left ventricular sensing: Impact of the desynchronization-detection algorithm

The use of CRT-D devices with left ventricular (LV) sensing has created controversy about programming various parameters especially the left ventricular T wave protection (LVTP) designed to prevent the delivery of a pacing stimulus into the LV vulnerable period. Such devices are available from two manufacturers. This review focuses only on those provided by Biotronik. As the LVTP controls LV sensing, some investigators have advocated turning off the LVTP to prevent episodic desynchronization known a CRT pacing interrupt. However, LVTP off reduces but does not eliminate this type of desynchronization if triggering of an LV stimulus upon right ventricular sensing (RVs) is programmed on. Deactivation of the LVTP incurs loss of diagnostic data provided by CRT pacing interrupt itself. By choice, the occurrence of CRT pacing interrupt can be totally eliminated by appropriate programming of the LV upper rate interval, LVTP and triggering of an LV pacing event upon RVs. Various programmability options are available according to clinical circumstances. As a rule, clinical judgement must weigh the potential diagnostic benefit of preserving the LVTP capable of recording of episodic CRT pacing interrupt against the loss of diagnostic benefit when LVTP is programmed off (with or without triggering of an LV stimulus upon RVs).

Loss of cardiac synchronisation due to automatic sense testing

In the latest generation Biotronik cardiac resynchronisation devices, cardiac resynchronisation therapy (CRT) may be inadvertently interrupted due to automatic sense testing. This issue can easily be recognized during device interrogation by the 'CRT interrupt warning' To avoid CRT interruption, both understanding of the algorithm and correct device programming are critical. The automatic sense testing algorithm has no built-in protection to avoid CRT interrupted pacing. When implanting this generation of devices programming needs to be adequate to avoid the occurrence of this phenomenon. This article is protected by copyright. All rights reserved.