PO-04-080 AN UNUSUAL CASE OF LEFT BUNDLE BRANCH AREA PACING LEAD MALFUNCTION

Abstract

Left Bundle Branch Area Pacing (LBBAP) is being used for conduction system/physiological pacing. It is important to be aware of manifestations and causes of LBBAP lead malfunction. Identify set screw and connector block damage as a cause of LBBAP lead malfunction with varying pacing parameters. N/A 78 years old lady with dual chamber permanent pacemaker for sick sinus syndrome developed progressive rate related left bundle branch block with left ventricular (LV) systolic dysfunction. She underwent upgrade to a cardiac resynchronization therapy-pacemaker device with addition of LBBAP lead (SelectSecure 3830 Medtronic lead) with confirmation of lead position by typical LBBAP parameters and demonstration of optimal septal penetration on contrast administration (Figure). Unipolar and bipolar lead tip impedance was found to be extremely elevated at follow-up interrogation with elevated LBBAP threshold. Over the next few weeks, LBBAP lead impedance varied between 1000 to >3000 Ohms with variable capture threshold 1.2 to >5 Volt at 0.4 milliseconds (ms) (Figure). Bipolar pacing at capture threshold was septal morphology with only variable typical LBBAP pattern, consistent with anodal capture. LBBAP lead position appeared stable on chest X-ray and transthoracic echocardiogram without clear lead discontinuity. Available near-field electrogram (EGM) on device interrogation showed no noise with provocative maneuvers. Patient underwent elective lead revision. Trans esophageal echocardiogram (TEE) prior to pocket access confirmed stable lead position with adequate septal penetration without protrusion into LV (Figure). On opening the pocket, the 3830 lead was found to be minimally retracted in the header and was easily pulled out manually. Lead parameters including sensing, impedance and capture threshold were normal with selective LBBAP and local LBB potential (Figure). The lead remained loose within the header after set screw deployment. These findings were reproduced with right ventricular (model 5076) lead indicating set screw failure. A new pacemaker generator was implanted with consistently stable LBBAP parameters on follow-up. The explanted generator analysis showed LV setscrew socket and connector block damage (Figure). Set screw failure is a rare cause of pacemaker lead failure. LBBAP lead set screw failure may manifest in an atypical manner without lead noise and should be suspected in acute lead malfunction.