412. What is exit block and what are its causes? / Most common cause of undersensing / What does undersensing look like on ECG? July 11th, 2008 by reuben in pacemaker Back Top Tags: card 411. What is the first sign of battery voltage depletion? / Most common cause of failure to capture / Where do leads commonly displace? / Where do lead fractures occur? 413. What does oversensing look like on ECG? / What is runaway pacemaker and endless loop tachycardia? / What therapy may interrupt pacemaker-mediated tachycardia? Leave a Reply Cancel reply Please post any discussion to the emupdates Reddit page.