Left ventricular sensing in cardiac resynchronization devices—opportunities and pitfalls for device programming

Abstract

Introduction: Some cardiac resynchronization therapy (CRT) device manufacturers (Biotronik, Germany; Boston Scientific, United States) have implemented left ventricular (LV) sensing functionality to prevent pacing into the vulnerable phase.Physicians are only partially aware of programming pitfalls related to LV sensing and general programming advice is lacking. Methods and Results:We provide an illustrative case-series-based review of the variety of potential problems with LV sensing. LV sensing may inappropriately impair CRT delivery due to LV-sensing issues or improper device programming. This can cause beat-wise loss of resynchronization but also ongoing desynchronization. On the other hand, LV sensing provides additional diagnostic information, which may reveal intermittent problems of the LV lead such as capture loss.We summarize the available evidence to provide manufacturer-specific recommendations on device programming and troubleshooting for daily clinical practice.Conclusion: CRT devices with LV sensing may suffer from impaired resynchronization due to programming pitfalls. If LV sensing is active (nominal setting in Biotronik and Boston Scientific devices), careful lookout for related problems and resynchronization percentage is required. Optimization is mandatory and even deactivation of LV sensing may have to be considered. K E Y W O R D S cardiac resynchronization therapy, left ventricular lead, left ventricular sensing, lock-in

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

“…The programmed duration of the LVURI or LVPP plays a crucial role in this situation and has a deleterious effect on biventricular pacing (Figure 4). The appearance of lock‐in in devices from Boston Scientific seems unlikely, as the sensing in these devices is coupled with a nonprogrammable LV refractory period of at least 250 ms 12 . This refractory period would cover even long interventricular delays (RVp‐to‐LVs), preventing sustained lock‐in.…”

“…However, LV sensing is not only used to monitor the LV lead but is also associated with LV pacing inhibition (ie, to prevent pacing during the vulnerable phase of the cardiac cycle). This can reduce the amount of biventricular pacing and even trigger arrhythmias 10‐12 …”

Left ventricular inhibition during cardiac resynchronization caused by sensed left‐sided ventricular premature complexes

“…BIOTRONIK and Boston Scientific devices used for CRT can sense from the LV lead . LV sensing was designed primarily to prevent competitive pacing outside the LV myocardial absolute refractory period and it works by inhibiting the release of an LV stimulus in the vulnerable period of the LV myocardium.…”

“…LV sensing in Boston Scientific and BIOTRONIK CRT devices do not influence traditional DDD RV timing cycles. The special LV sensing function is based on limitation of the LV pacing rate by means of the LVURI . The LV Protection Period of Boston Scientific devices (LVPP) is equivalent to the LVURI .…”

“…The special LV sensing function is based on limitation of the LV pacing rate by means of the LVURI . The LV Protection Period of Boston Scientific devices (LVPP) is equivalent to the LVURI . This LVURI is initiated only by an LV paced event (LVp) or an LV sensed event (LVs), and the interval duration is programmable.…”