A man with two pacemakers: the mystery of the electrocardiogramYingchun Hu1*, Xiaoyu Chen2*, Hui Huang1, Weiming Luo1,Yisheng Zhou1, Xingkao Chen1, Guoping Liu1, Hanping Zhang1#1Department of Cardiology, Guangzhou Development District Hospital, 196 Youyi Road, Huangpu District, Guangzhou 510730, Guangdong, China2Department of Nephrology, Rheumatism and Immunology, Chongqing Jiulongpo People’s Hospital, Chongqing, 400050, China* These authors have contributed equally to this work and were both the first authors.# The author is the corresponding author.# Correspondence to : Hanping ZhangE-mail: [email protected] to: Department of Cardiology, Guangzhou Development District Hospital, 196 Youyi Road, Huangpu District, Guangzhou 510730, Guangdong, ChinaKey words: electrocardiogram, pacemaker, battery depletion, pacing spikes, His bundle pacingKey Clinical MessageThe increasing growth in the elderly population and expanding indications for pacemaker use have led to a progressive rise in the number of pacemaker implants. As the number of pacemaker implants continues to grow, the demand for pacemaker replacements also increases. Therefore, regular follow-up and timely detection of pacemaker issues are particularly important. Our findings reported a confusing but interesting clinical practice. In our study, three spike signals are observed during stable pacing periods, with fixed spikes occurring during in AV delay at 180 ms intervals, excluding other operation types such as CRT and His bundle pacing.