Performance Evaluation Of Traditional Endocardial Pacing System And Clinical Feasibility Study Of Non - Wire Pacemaker

Part I.Long-term Reliability and Durability of Traditional Pacing SystemAims:Cardiac pacemaker therapy has been the cornerstone of the bradyarrhythmia treatment. However, there are limited data regrading long-term reliability and durability of pacemaker generators and endocardial pacing leads. The aims of the present study were to access the reliability and durability of pacing system, and to identify the replacement causes of generators and leads.Methods:Adult patients undergoing endocardial pacing system replacement between year 1990 and 2013 at Fuwai hospital were included. Long-term performances of generators and leads were retrospectively evaluated and reasons for replacement were identified.Results:A total of 2369 leads in 1403 patients were included. During a mean period of 9.1±3.1 years,1538 generators and 120 leads were replaced. The average longevity of generators was 8.3±2.4 years, and more than 92% of the devices were removed for normal battery depletion. Devices replaced for premature battery depletion, recall advisory, infection, and device upgrade accounted for 4.0%,1.6%, 1.1%, and 0.5% respectively. The annual rates for normal device removal had increased over time. The cumulative lead survival at 5,10,15 years were 99.0%, 93.7%, and 84.9% respectively. Unacceptable electrical performance was principal reason for lead replacement, and the incidence of lead integrity failure was 1.6%. Dislocation, infection, device upgrade resulted in 0.5%,0.5%, and 0.4% lead replacement respectively. In leads implanted more than 10 years, the electrical performances were stable within the accepted range.Conclusions:During the past 24 years, the vast majority of pacing systems in this study had satisfactory performances. Battery longevity was durable and the generator capability was improved over time. Long-lasting reliability and electrical stability were observed in leads.Part Ⅱ.Incidence, risk factors, and outcome of lead-related tricuspid regurgitation in patients with ventricular lead implantationAims:Although complications induced by lead implantation have been extensively studied, the systematic evaluations of lead-related tricuspid regurgitation (TR) are very limited. This study aimed to determine the incidence, risk factors and outcome of lead-related TR in patients implanted with ventricular lead.Methods:Patients undergoing cardiac rhythm devices implantation and at least one replacement between January 2000 and December 2014 at Fuwai hospital were included. Echocardiographs done prior to implantation and replacement were retrospectively analyzed. Patients were followed up by outpatient visit or telephone contact, whose all-cause mortality and cardiac death were recorded.Results:A total of 705 patients were included. Lead-related TR (TR increasing ≥2 grades) was found in 245 patients (34.8%) during a mean period of 8.0±1.8 years after implantation, which was statistically associated with marked enlargements of right atrium and right ventricle. Age (p=0.012), atrial fibrillation (p＜0.001), and pre-implantation TR grade (p<0.001) were independent predictors of lead-related TR. During a mean follow-up of 4.5±2.4 years, patients without lead-related TR exhibited better life survival of all-cause mortality and cardiac death (log rank p=0.019 and p=0.044 respectively). Lead-related TR was associated with higher risk of all-cause mortality and cardiac death in multivariate Cox regression model (P=0.007 and P=0.026 respectively).Conclusion:Lead-related TR is common and associated with age, atrial fibrillation and pre-implantation TR grade. Patients with lead-related TR had higher risk of all-cause mortality and cardiac death in the long-term.Part III.Effect of Multiple Transcatheter Pacemakers Implanted in the Right Ventricle on Cardiac Function in SwineAims:The transcatheter leadless pacemaker has recently emerged as a bradycardia therapy in humans and many patients may need at least two transcatheter pacemakers in their lifetime. The present study aimed to assess the impact of two transcatheter pacemakers (Micra) in the right ventricle on cardiac function in a swine model.Methods:A total of 25 mini pigs were chronically studied,14 received Micra devices (the test group) and 11 received defibrillation leads (the control group). Each animal received either two Micra devices or two defibrillation leads in the right ventricle with one month between two separate implants. All animals were then followed for 6 months. Cardiac function was assessed with echocardiograph at baseline, the second implant, and the end of the 6-month follow-up. The necropsy was performed to measure the length of fibrous tissue attaching the devices or leads and assess the tricuspid valve injury.Results:There were no significant changes in left ventricular ejection fraction and cardiac output from baseline to the end of the study in either group. The length of fibrous tissue attaching on Micra devices was 14.3±7.8 mm that was significantly shorter than that attaching to defibrillation leads (86.5±26.1mm, p=0.01vs. the test group). The tricuspid injury was observed in 4 animals of the control group but not in the test group (P=0.004 between two groups).Conclusion:Multiple Micra devices implanted in the right ventricle do not negatively impact on cardiac function when compared to transvenous defibrillation leads. The finding supports the safe use of multiple Micra devices.