Percutaneous epicardial placement of a prototype miniature pacemaker under direct visualization: An infant porcine chronic survival study

Emerging Technologies for the Smallest Patients

Pediatric and congenital heart disease patients may require cardiac implantable electronic device implantation, inclusive of pacemaker, ICD, and implantable cardiac monitor, for a variety of etiologies. While leads, generators, and monitors have decreased in size over the years, they remain less ideal for the smallest patients. The potential for a miniature pacemaker, fetal micropacemaker, improving leadless technology, and rechargeable devices creates hope that the development of pediatric-focused devices will increase. Further, alternative approaches that avoid the need for a transvenous or surgical approach may add more options to the toolbox for the pediatric and congenital electrophysiologist.

Percutaneous epicardial pacing in infants using direct visualization: A feasibility animal study

BACKGROUND

Pacemaker implantation in infants and small children is limited to epicardial lead placement via open chest surgery. We propose a minimally invasive solution using a novel percutaneous access kit.

OBJECTIVE

To evaluate the acute safety and feasibility of a novel percutaneous pericardial access tool kit to implant pacemaker leads on the epicardium under direct visualization.

METHODS

A custom sheath with optical fiber lining the inside wall was built to provide intrathoracic illumination. A Veress needle inside the illumination sheath was inserted through a skin nick just to the left of the xiphoid process and angled toward the thorax. A needle containing a fiberscope within the lumen was inserted through the sheath and used to access the pericardium under direct visualization. A custom dilator and peel-away sheath with pre-tunneled fiberscope was passed over a guidewire into the pericardial space via modified Seldinger technique. A side-biting multipolar pacemaker lead was inserted through the sheath and affixed against the epicardium.

RESULTS

Six piglets (weight 3.7-4.0 kg) had successful lead implantation. The pericardial space could be visualized and entered in all animals. Median time from skin nick to sheath access of the pericardium was 9.5 (interquartile range [IQR] 8-11) min. Median total procedure time was 16 (IQR 14-19) min. Median R wave sensing was 5.4 (IQR 4.0-7.3) mV. Median capture threshold was 2.1 (IQR 1.7-2.4) V at 0.4 ms and 1.3 (IQR 1.2-2.0) V at 1.0 ms. There were no complications.

CONCLUSION

Percutaneous epicardial lead implantation under direct visualization was successful in six piglets of neonatal size and weight with clinically acceptable acute pacing parameters.

Design and Functionality of a Multilumen Thoracic Access Port for Pericardial Access Under Direct Visualization

Small vasculature, venous obstruction, or congenital anomalies can preclude transvenous access to the heart, often resulting in open chest surgery to implant cardiac therapy leads for pacing, defibrillation, or cardiac resynchronization. A minimally invasive approach under direct visualization could reduce tissue damage, minimize pain, shorten recovery time, and obviate the need for fluoroscopy. Therefore, PeriPath was designed as a single-use, low-cost pericardial access tool based on clinical requirements. Its mechanical design aids in safe placement of conductive leads to the pericardium using a modified Seldinger technique. The crossed working channels provide an optimal view of the surgical field under direct visualization. Finite element analysis (FEA) confirms that the device is likely not to fail under clinical working conditions. Mechanical testing demonstrates that the tensile strength of its components is sufficient for use, with minimal risk of fracture. The PeriPath procedure is also compatible with common lead implantation tools and can be readily adopted by interventional cardiologists and electrophysiologists, allowing for widespread implementation. Prior animal work and a physician preliminary validation study suggest that PeriPath functions effectively for minimally invasive lead implantation procedures.

Epicardial implantation of a leadless pacemaker in a lamb model

BACKGROUND

Pacemaker used in small children typically consist of an abdominally placed generator and epicardially affixed leads, making such a system prone to lead dysfunction during growth. Aim of this study was to investigate the feasibility of epicardial pacing with a leadless pacemaker in a lamb model.

ANIMALS AND METHODS

Seventeen lambs underwent epicardial implantation of a Micra transcatheter pacing system (TPS) (Medtronic, Minneapolis, MN, USA) via left-lateral thoracotomy to the left ventricle (LV) surface (n = 11/17) and to the left atrial appendage (n = 6). Ventricular devices were fixated with the tines within the pericardium, whereas the tines of the atrial devices penetrated the myocardium of the left atrial appendage. After 31 weeks, animals were sacrificed and hearts were explanted for histological analysis.

RESULTS

Following implantation, median P/R amplitude was 4.25/5.5 mV while median pacing threshold was 1.1/1.9 V at 0.24 ms. After 31 weeks, median P/R amplitude was 3.3/4.2 mV. Median atrial pacing threshold was 0.5/0.24 ms. Eight of 10 ventricular pacemakers had lost capture at standard impulse width even at maximum impulse amplitude. On explantation, firm adhesion of the device to the thoracic wall and dislodgement of the electrode tip was found in those ventricular devices.

CONCLUSIONS

Firm fixation of the Micra electrode to the epicardial surface as applied to the atrial devices resulted in excellent electrical properties during midterm follow up. Pericardial fixation as in the ventricular devices was associated with loss of capture. Therefore, it is important to embed the tines in the myocardium and to choose an alternative implantation site allowing for safe fixation of the Micra TPS in a position perpendicular to ventricular epimyocardium.

The Future of Percutaneous Epicardial Interventions

The pericardial space provides a unique vantage point to access different cardiac structures for diagnosis and treatment of arrhythmias and other nonelectrophysiologic conditions, such as heart failure. There have been notable innovations to improve safety of percutaneous pericardial access and its use for various procedures. Percutaneous pericardial device therapies for pacing and defibrillation have been in development, success of which will be a significant advance in treatment of bradyarrhythmias, cardiac resynchronization therapy, and prevention of arrhythmic deaths. There is need for continued efforts in development and expansion of this technique and a systematic approach to monitor efficacy and safety outcomes.