Understanding the Timing Cycles of a Cardiac Resynchronization Device Designed with Left Ventricular Sensing

Abstract

Some devices used for cardiac resynchronization therapy (CRT) can sense from the left ventricular (LV) lead as in Biotronik CRT devices (Biotronik GmbH, Berlin, Germany), whose special LV timing cycles form the basis of this report. LV sensing (LVs) was designed to prevent competitive pacing outside the LV myocardial absolute refractory period. LVs works by inhibiting the release of an LV pacemaker stimulus (LVp) in the vulnerable period of the LV during a programmable period. LVs with stored LV electrograms may also provide recordings of diagnostic value in tachyarrhythmias. LVs has added a new dimension to the evaluation of the function of CRT devices, because it is manifested by unfamiliar timing cycles. In this respect, Biotronik devices can initiate an LV upper rate interval (URI) upon sensing a right-sided event when LVs is turned off. An inhibited LVp can also initiate an LVURI. The LVURI should generally be programmed to a relatively short duration and shorter than the right ventricular URI to prevent a special form of desynchronization arrhythmia sustained by LVs. This arrhythmia is characterized by recurring delayed LVs events in sequences associated with RV pacing followed by LVs events with loss of LVp.

Inhibition of left ventricular stimulation due to left ventricular lead failure and the left ventricular T‐wave protection algorithm in patient with cardiac resynchronization therapy and pacemaker dependency

“…These include T‐wave oversensing by the LV channel and far‐field atrial sensing by the LV channel before RV activity during sinus rhythm and atrial tachyarrhythmia (D'Ivernois & Barold, ). Moreover, when LVURI interval is longer than RV upper tracking interval resynchronisation stops due to repeated LVURI restarting (Barold & Kucher, ; Barold, Mello Porto, & Kucher, ).…”

“…The mechanism which explains the intermittent loss of resynchronization is an algorithm LVTP set to on. In Biotronik CRT devices, the LVURI controls the delivery of LV stimulation (Barold & Kucher, ). LVURI is started by ventricular sensing, either via LV channel when LVTP is turned on, or via RV channel when LVTP is turned off.…”

Loss of cardiac resynchronization therapy in a patient with a biventricular implantable cardioverter‐defibrillator

“…LVURI should be programmed shorter than the RVURI, and the difference should be sufficient in order to compensate for the interventricular delay [2]. Otherwise, it can lead to a form of desynchronization arrhythmia, which is characterized by RV pacing followed by an LV sensed event and loss of LV pacing (like in our patient).…”

“…The difference is about LV sensed events. When the left ventricle T‐wave protection (LVTP) function is on, LV sensed events will start an LVURI, but when LVTP is programmed off, then the device cannot sense LV events and instead sensed RV events will initiate and reset an LVURI [1,2].…”

Left ventricular sensing by cardiac resynchronization devices

“…An LVs event detected during the LVPP will restart the LVPP. In contrast, the LV T wave protection (LVTP) of BK devices that controls LV sensing can simply be turned on or off and, therefore, it has no measurable duration …”