Multiple leadless pacemakers implanted in the right ventricle of swine.

Aims: The miniaturized leadless pacemaker has recently emerged as a bradycardia therapy in humans, and many patients may need at least two pacemakers in their lifetime. Thus, the present study assessed the effect of two leadless pacemakers in the right ventricle (RV) on cardiac function in a swine model.

Methods And Results: Fourteen mini pigs were chronically studied. Each animal received two sequential leadless pacemakers in the RV with 1 month between two separate implantations. All animals were then followed for 6 months. Cardiac function was assessed with echocardiography at baseline, the second implantation, and the end of the 6-month follow-up. A necropsy at the end of the study was performed to measure the length of the fibrous tissue covering the devices and assess tricuspid valve integrity. Four animals died during the surgical procedure, and one animal died of infection during the follow-up period. In the remaining nine animals, there were no significant changes in left ventricular ejection fraction, aortic time integral, cardiac output, and left ventricular size from baseline to the end of the study. The mean length of fibrous tissue covering Micra devices was 14.3 ± 7.8 mm. No tricuspid valve injury was observed.

Conclusion: Multiple leadless pacemakers implanted in the RV do not appear to impact cardiac function. Therefore, it appears safe to implant multiple leadless pacemakers in the same heart.