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.
Our data demonstrate the necessity of systematic postmortem CIED interrogation in forensic medicine to determine the cause and timing of death more accurately. In addition, CIED analysis is an important tool to detect potential CIED-related safety issues.
cardiac resynchronization, cardiac pacing, left ventricular sensing, T wave oversensing sensing, implantable cardioverter-defibrillatorClinical Summary A 60-year-old man received a transvenous cardiac resynchronization device (Biotronik Lumax 340 HF-T, Biotronik, Berlin, Germany) 1 in 2009 for a nonischemic cardiomyopathy congestive heart failure (left ventricular [LV] ejection fraction = 26%), and complete left bundle branch block. LV pacing and sensing were performed from the tip and ring electrodes of the LV lead. Infrequent intermittent T-wave oversensing by the right ventricular (RV) channel involving only one or two spontaneous beats was first detected in November 2012. The RV sensitivity was left at 0.8 mV but the sensing LV amplifier was turned off. At the time of a follow-up 1 month later, the parameters were as follows: Low rate = 60 pulses per minute (ppm), RV and LV upper rate = 130 ppm (upper rate interval = 460 ms, RVURI = RV upper rate interval, LVURI = LV upper rate interval), postventricular atrial refractory period = 250 ms (475 ms after a ventricular premature complex [VPC]), paced atrioventricular (AV) delay = 100 ms, sensed AV delay = 80 ms, upper threshold = 75% (programmed sensitivity becomes 75% of the maximum, lasting for 350 ms), amplitude mode for detection of the peak R wave, and high pass 1 = 20 Hz, LV lead impedance = 545 Ohms. LV blanking after sensing was 200 ms before the LV-sensing amplifier was turned off. The AV control (AVC) window (discrimination after atrial sensing) was 350 ms, interventricular delay basically zero (triggered delay = 3-5 ms), and triggered function (LV-paced events [LVp]) after RV sensing (RVs) was within the AVC window. The LV sensitivity was not reprogrammed and
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