A Rationale for Minimally Invasive Permanent Pediatric Pericardial Pacing Device Implantation

DOI: 10.19102/icrm.2015.060605

¹CHRISTOPHER P. JORDAN, MD, ²FAHAD A. ALFARES, MD, ¹JEFFREY P. MOAK, MD, ²DILIP S. NATH, MD, ¹CHARLES I. BERUL, MD

¹Division of Cardiology, Children’s National Medical Center, Washington, DC

²Cardiovascular Surgery, Children’s National Medical Center, Washington, DC

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ABSTRACT. Epicardial device implantation in small children and patients with congenital heart defects (CHDs) presents the cardiologist and surgeon with unique challenges. These patients are often too small for implanters to insert the pacemaker or implantable cardioverter-defibrillator (ICD) lead via the standard transvenous approach. This report reviews our single-institutional 5-year surgical epicardial device implantation experience in infants and smaller pediatric patients (<15 kg) and offers insight into the rationale for future minimally invasive pericardial device implantation as the preferred approach for infants, small children, and CHD patients for whom a transvenous approach is contraindicated. We reviewed all patients of less than 15 kg undergoing epicardial device implantation (pacemaker or ICD) via median sternotomy or thoracotomy between January 2009 and December 2013, including demographics and implant characteristics. The median age for the pacemaker implantation was 1.1 year, with median weight of 7.2 kg and median height of 67.7 cm. The most common indication for placement of an epicardial device was heart block, either congenital or postoperative (43%), followed by sinus node disease, either congenital or postoperative (27%). Three patients required device revision. During the period from 2009 to 2014, six patients (16%) died, all within the first year following pacemaker placement, but none of the deaths related to the pacemaker surgery. Infants and congenital heart disease patients requiring permanent pacemaker or ICD make up a small but important patient population for whom the standard transvenous approach may be complicated by anatomical complexities, such as small veins or absence of standard venous connections. For patients requiring a non-transvenous device, the current standard of epicardial device implantation via median sternotomy or thoracotomy entails multiple inpatient days, including a stay in the cardiac intensive care unit, and prolonged recovery times, as well as pain and associated mediastinal scarring and adhesions. All of these issues could be improved upon with implementation of a minimally invasive pericardial device insertion technique for human infants and CHD patients. At less than 15 kg, the patients reviewed in this series are the target human population for this approach.

KEYWORDS. congenital heart disease, innovation, pacemaker, pediatrics.

Dr. Berul reports he has received a research grant from Medtronic, Inc.
Manuscript received March 21, 2015, Final version accepted May 3, 2015.

Address correspondence to: Address correspondence to: Charles I. Berul, MD, Children’s National Medical Center, 111 Michigan Ave NW, Washington, DC 20010. E-mail: cberul@childrensnational.org

Introduction

Epicardial device implantation in small children and patients with congenital heart defects (CHDs) presents the cardiologist and surgeon with unique challenges. These patients are often too small for implanters to insert the pacemaker or implantable cardioverter-defibrillator (ICD) lead via the standard transvenous approach. CHD patients may have congenital anomalies of the venous system, which preclude the ability to insert a pacemaker lead through the venous system to the correct position in the heart. Previous work from our group demonstrates both proof of concept and feasibility of thoracoscope-guided minimally invasive epicardial pacemaker lead implantation in an infant-sized animal model.¹ Using a subxiphoid approach similar to pericardiocentesis, we described techniques to access the pericardial space, and fixate a lead over the body of either the atria or the ventricle in an infant-sized animal model. This report reviews our single-institutional 5-year surgical epicardial device implantation experience in infants and smaller pediatric patients (<15 kg) and offers insight into the rationale for future minimally invasive pericardial device implantation as the preferred approach for infants, small children and CHD patients for whom a transvenous approach is contraindicated (Table 1).

Methods

Patients

We reviewed all patients of less than 15 kg undergoing epicardial device implantation (pacemaker or ICD) via median sternotomy or thoracotomy between January 2009 and December 2013, including demographics and implant characteristics. Approval for chart review was obtained from the Children’s National Health System Institutional Review Board. Variables of interest include age, sex, diagnosis, indication for device, lead implantation route and location, complications, and outcomes as documented in the medical record. Device interrogation data include atrial and/or ventricular pacing capture thresholds, atrial and/or ventricular sensing thresholds, and lead impedance. All patient records were reviewed under an approved institutional review board protocol. During the 5-year review period, 37 patients underwent permanent pacemaker placement. Device interrogation data were available at discharge, 3 months, 6 months and 1 year postoperatively with a maximum follow-up of 5 years. One patient with long QT (LQTS) syndrome had an epicardial ventricular pacing system placed as an infant that was later converted to an ICD during the study period.

Surgical technique

The surgical approach was via median sternotomy, lower sternotomy, or left thoracotomy. A 25-cm lead length was selected in all patients with pacing systems, utilizing steroid-eluting epicardial leads (bipolar model 4968 or unipolar model 4965, Medtronic, St. Paul, MN). In 36 patients, a subrectus pocket was created and irrigated with antibiotic solution; the generator was fixed to the linea alba using an interrupted 2-0 Ethibond suture (Ethicon, Inc, Somerville, NJ). One patient had the generator placed in a left thoracic pocket. Patients were managed postoperatively in the cardiac intensive care unit with regular device interrogations performed by the electrophysiology service.

Results

Patient characteristics

The median age for pacemaker implantation was 1.1 year, with median weight 7.2 kg and median height 67.7 cm. Seventeen patients (45.9%) had a structurally normal heart. Twenty patients had structural congenital heart disease: d-transposition of great arteries (TGA) (3), complete atrioventricular (AV) canal (4), ventricular septal defects (VSDs) (2), single ventricle anatomic variants (4), and miscellaneous cardiac defects (7). The most common indication for placement of an epicardial device was heart block, either congenital or postoperative (43%), followed by sinus node disease, either congenital or postoperative (27%). Four patients (11%) required pacemaker insertion because of LQTS. One LQTS patient went on to receive an epicardial ICD because of medically refractory ventricular tachycardia (VT).

Pacemaker data and lead performance

Table 2 demonstrates the electrical performance for the atrial and ventricle pacing leads 1 year postoperatively. The median pacing threshold for atrial and ventricle leads remained below 0.9 V and 1.25 V, respectively. Three patients required device revision. One LQTS patient had persistent VT despite VVI pacemaker and medical management, and a decision was made to upgrade to a dualchamber ICD system, using a pericardial defibrillator coil.² The second patient requiring surgical revision had congenital complete heart block secondary to maternal lupus and developed severe left ventricular dysfunction, which improved with conversion to a dual-chamber biventricular pacing system.^3,4 The third patient developed left-sided phrenic nerve palsy following implantation of an epicardial unipolar DDD pacemaker (left atrial and left ventricular leads), and after that he presented with loss of capture of the ventricular lead and pacemaker dysfunction. The pacing system was revised to a DDD bipolar pacing system (right atrial and left ventricular pacing leads).

Survival and mortality

During the period from 2009 to 2014, six patients (16%) died, all within the first year following pacemaker placement, but none of the deaths related to the pacemaker surgery. Three patients died of respiratory failure, two patients died of cardiogenic shock as a complication of their cardiac surgery, and one patient died of pulmonary hypertension. During the study period, three additional patients were lost to follow-up in the first year, and one patient in the second year.

Discussion

Infants and congenital heart disease patients requiring a permanent pacemaker or ICD make up a small but important patient population for whom the standard transvenous approach may be complicated by anatomical complexes: small veins or absence of standard venous connections. For patients requiring a non-transvenous device, the current standard of epicardial device implantation via median sternotomy or thoracotomy entails multiple inpatient days, including a stay in the cardiac intensive care unit, and prolonged recovery times, as well as pain and associated mediastinal scarring and adhesions. All of these issues could be improved upon with implementation of a minimally invasive pericardial device insertion technique for human infants and CHD patients. At less than 15 kg, the patients reviewed in this series are the target human population for this approach. The direct visualization of critical cardiac structures, as we previously reported¹ is essential to minimizing risk of inadvertent injury, especially as the standard open approach has proven long-term safety and efficacy.^5–7 Other groups have demonstrated similar minimally invasive techniques for pacemaker insertion in larger animal models and patients.^8,9

The majority of devices (28/37) in this cohort were indicated for reasons other than postoperative heart block, and nearly half (17/36) of all patients had normal cardiac anatomy. Thus, many patients in need of a pacemaker or ICD who are too small for the standard transvenous approach might avoid these large incisions. Reported known adverse outcomes from sternotomy incisions include mediastinal adhesions and its attendant long-term associated risks, phrenic and vagal nerve injury, and scoliosis.^10,11 Although the absolute risk of complication from sternotomy is low, under the current state of the art these infants face repeated procedures for lead revision and possible removal over the course of a lifetime that is, hopefully, many decades in duration. Placement of these non-removable pacing leads prevents the patient from being eligible for future magnetic resonance imaging studies, particularly when abandoned.

Ongoing survival studies in our animal model are under way to establish safety and efficacy of our proposed alternative minimally invasive approach. Percutaneous pericardial lead insertion may ultimately prove to be feasible in the adult congenital heart disease (ACHD) population as well. ACHD patients requiring device therapy are also constrained by contraindications to transvenous lead implantation at higher rates than the general adult population with normal intracardiac anatomy. These patients present the added challenge of overcoming adhesions or obliteration of the pericardial space not seen in infants and small children without prior cardiac surgery. Innovations benefiting this unique and growing population of patients who consume disproportionately vast amounts of health-care resources should help reduce cost and shorten the postoperative length of stay.

References

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