A New Minimal-Invasive Concept for Permanent Epicardial Pacing Shows Promising Acute and Long-Term Results in an Infant Swine Model

Objectives: Epicardial pacing often is the best (and sometimes only) choice in congenital heart disease although it requires open heart surgery. To avoid the associated trauma, we developed a new percutaneous pericardial implantation technique utilizing 3D steerable catheters to deliver prototype bipolar screw-in leads. Feasibility and chronic performance was tested in an infant animal model.

Methods: Subxiphoidal micro puncture (22 G) was used to establish pericardial access in 13 minipigs (15.2 ± 2.3 kg). Steerable delivery catheters were introduced under fluoroscopic guidance. The leads were fixated in atrial and ventricular positions. Lead function was evaluated by measurement of intrinsic P/R wave signal, pacing threshold (PT) and impedance. Cardiac structures were visualized by angiography. Weekly follow-up measurements were performed up to 12 (n = 11) resp. 24 (n = 4) weeks. Macroscopic and histologic results were correlated to the electrical performance.

Results: Fully functional dual chamber pacemakers were successfully implanted in all 13 animals. One animal died at the end of implantation not procedure related and one dropped-out after 2 months due to infection. Absence of vascular or myocardial injury was documented. Acute, 12 week and 24 week follow-up data are summarized below.

Acute electrical performance of all leads was excellent. During follow-up ventricular lead function remained stable. For the atrial site relevant deterioration was noted in 4 animals, but no exit block occurred. Unipolar pacing was superior over bipolar pacing. Increased PTs were associated with more superficial tissue penetration and increased fibrotic reaction.

Conclusion: Feasibility and safety of the method was proven. Lead performance, especially for the ventricular position, remained good during long- term follow-up. This new approach has the potential to achieve synchronous selective pacing with a less invasive approach and improved long-term performance compared with current practice.