Cardiac Pacing in Neonates, Infants, and Preschool Children PAUL C. GILLETTE, VICKI L. ZEIGLER, AMY T. WINSLOW, and JOHN M. KRATZ From the South Carolina Children's Heart Center, Medical University of South Carolina, Charleston, South Carolina GILLETTE, P.C., ET AL.: Cardiac Pacing in Neonates, Infants, and Preschool Children. A series of 37
children < 5 years old at pacemaker implant were followed from 1 to 105 months. Five of 37 patients required reoperation for battery depletion while two required reoperation for exit block of epicardial ventricular leads. Each patient paced in the DDD or AAI mode was still in the original mode at the end of follow up. (PACE, VoJ. 15, November, Part II 1992) neonatal pacing, pediatric pacing, transvenous pacing
Introduction Cardiac pacing is being increasingly prescribed for neonates, infants, and young children.^ This is partially because physicians and other health care professionals who care for these children are more aware of potential symptomatic bradydysrhythmias and because cardiac surgery is being performed in smaller children with increasingly more complex cardiac defects. The techniques and results of cardiac pacing in adults and older children have been well described in the literature. We therefore, set out to review our experience with cardiac pacing in children < 5 years old over an 8-year period at the Medical University of South Carolina. Methods Data were collected from the records of the Pediatric Cardiac Pacemaker Clinic, as well as from the implant records of the operating room and cardiac catheterization laboratory of the South Carolina Children's Heart Center. The patient's outpatient charts and records of electrocardi-
Address for reprints: Paul C. Gillette, M.D., Medical LFniversity of South Carolina, South Carolina Children's Heart Center, 171 Ashley Avenue, Charleston, SC 29425. Fax: (803) 792-3284.
2046
ograms and Holter monitors were also reviewed. The patient's follow up in the Pediatric Pacemaker Clinic began immediately after implant and continued at 6 weeks, 6 months, and yearly thereafter. Transtelephonic follow up included weekly transmissions for the first 6 weeks, monthly transmissions for the rest of the first year, and 3-month transmissions thereafter. The patients were also instructed to send a telephone strip and voice message when concerned about the function of their pacing system, particularly after sustaining a physical trauma. Results Thirty-seven children had had implantation of a cardiac pacemaker at the Medical University of South Carolina before the age of 5 years. They ranged in age from 1 day to 57 months (mean = 23 months), and their weights ranged from 1.3 to 19.8 kg (mean = 10.3 kg). Their anatomical diagnosis showed that 14 had normal cardiovascular systems while 23 had had repairs of congenital heart defects (Table I). Their electrophysiological diagnosis are in Table II. The implantation technique was chosen according to the patient's characteristics.^ If an intracardiac shunt was present, an epicardial system was recommended. Patients under 5 kg w h o required a single lead received epicardial implants
November, Part II 1992
PACE, V o l . 15
PEDIATRIC PACING
Table I. Anatomical Diagnoses in Postoperative Children Requiring Permanent Pacing Senning/Mustard Septal defects Fontan Subaortic stenosis Complex CHD Cardiomyopathy
Table III. Pacing Mode
as well as patients under 10 kg who required dual chamber pacing. Other candidates for dual chamber implants were postoperative patients and patients with normal hearts but with depressed cardiac function. Using these criteria, 20 patients had endocardial and 17 had epicardial implantation. Pacemakers were carefully chosen to allow the pacing mode most appropriate to the patient's need. For example, patients who had atrial reentry tachycardia after repair of a transposition of the great arteries or a Fontan repair for a single ventricular complex, received a multiprogrammable atrial demand pacemaker capable of overdrive atrial pacing. Patients who had uncomplicated sinus bradycardia and who could be paced to an atrial rate of at least 120 without developing second-degree AV block, had implantation of an atrial demand pacemaker. Patients, who had complete AV block or high grade AV block, received dual chamber pacemakers initially programmed to the DDD mode. Patients, who had transient AV block but were considered to be at risk of sudden death or at risk of increase in degree of AV block, received ventricular demand pacemakers. Three pa-
Table II. Pacing Indications in Children < 5 Years of Age Congenital AV block Acquired AV block Electrical cardiomyopathy Sinus node dysfunction Atrial R/E tachycardia + sinus node dysfunction Others
PACE, Vol. 15
AAI VVI DDD
4 12 3 t 2 t
9 15 2 5 4 2
AAICP VVIR
3 13 14 4 3
tients had a ventricular demand rate responsive pacemaker implanted because no more than one lead could be introduced into the subclavian vein. Table III shows the pacing mode selected for the various patients. The pacemakers were selected very carefully for size and functionality. Because of these patients' very young age and small size, the smallest pacemaker available was chosen while providing the most possible programmability to meet the expected changing needs of this very young patient population. Implant Technique
Transvenous implantations were performed in the cardiac catheterization laboratory. A venous angiogram was performed to determine the anatomy of the subclavian vein and its suitability for positioning of the pacemaker lead. The angiographic catheter was left in the left subclavian vein to be used as a target during needle entry into the subclavian vein. The most common lead used was a bipolar, silicone insulated, screw-in, porous tipped electrode. More recently, a mannitolcoated lead has been used to facilitate manipulation across the tricuspid valve. A curved stylet was used to help the lead cross the tricuspid valve and approach the ventricular septum approximately one third of the way from the apex to the pulmonary valve. Therightventricular apex was avoided as a lead position because of possible pacing of the diaphragm. The atrial lead was screwed at the base of the right atrial appendage or other positions as necessary if the base of the right atrial appendage failed to give adequate signals or pacing thresholds. The leads were positioned further into the heart to try to leave small loops for growth. Large loops were not sought since it was felt that they
November, Part II 1992
2047
GILLETTE, ET AL.
might cause extrasystoles. The leads were sutured down at the subclavian puncture site, the pacemaker was interfaced and positioned in the subpectoral pocket, and telemetry testing of the entire pacing system was performed using a sterile programming wand. The muscle layer was then closed with 2-0 absorbable suture, as was the subcutaneous tissue, and the skin was approximated using a 4-0 absorbable suture and steri-strips. Epicardial Implant Technique The patients who received epicardial pacemakers had their implants in the operating room by a cardiovascular surgeon.^ Except for five patients in this series, myocardial stab-on or screwin leads were used. For the most part, screw-in leads with a 2H turn screw were used in the ventricle, whereas stab-on leads were used in the atrium. A few patients had a stab-on lead positioned in the ventricle and in the atrium. Five patients had implantation of an investigational steroid epicardial lead or leads that had no screw or barb. It was sutured to the myocardium using three suture holes and a plaque electrode affixed to the myocardium. Follow Up Implants were successfully completed in each patient. One patient died within 24 hours of pacemaker implantation of progressive preexisting congestive heart failure and respiratory failure. Seven patients died during follow up of congestive heart failure. None died suddenly and in none was the pacing system considered to have contributed to the death. Two patients were reoperated for epicardial ventricular lead problems. These were corrected by electively intervening when the output of the pulse generator had to be programmed at 8 V/1 msec. In both cases, the lead was replaced by a steroid epicardial ventricular lead. In one case, the threshold remained low over 1 year of follow up. In the other case, threshold rose again within months, and an endocardial steroid ventricular lead was substituted. Five patients underwent reoperation for replacements of epicardial units that had been programmed at relatively high output in order to keep an adequate safety margin for pacing. All patients who had two leads implanted are cur-
2048
rently paced in the DDD or DDI mode. All atrial leads are still functioning. Discussion Cardiac pacing has been used with increasing frequency in neonates, infants, and small children. This report demonstrates that it can be used safely and efficaciously. There is a trend towards using more and more transvenous units, which is justified since reoperations were necessary in two patients with epicardial leads. In addition, tke need for high pulse generator outputs in the epicardial group caused earlier battery depletion. Therefore, it seems justified to continue to attempt transvenous implantations in smaller and smaller children as techniques, lead sizes, and pacemaker sizes evolve. In order to perform this procedure safely, a dedicated catheterization laboratory experienced in catheterizing neonates as well as in performing electrophysiological studies and pacemaker implants is necessary. In addition, we have found the use of general anesthesia useful in infants under 1 year of age. Epicardial techniques have also improved considerably, and the size a dual chamber pacemaker is now the same as that of a single chamber device except for an extra lead header. Thus, if myocardial function is abnormal, or if there is a congenital cardiac defect, we recommend the implantation of a dual chamber pacemaker, even in neonates. The stab-on lead has recently been platinized, resulting in lower pacing thresholds, and the recent clinical trials with the steroid epicardial lead have been promising. There are still problems with fibrous adhesions from previous heart surgery. The implantation of the steroid sew-on epicardial lead is more difficult than the stab-on or screw-in systems, but lower pacing thresholds make the extra effort worthwhile. Other technical aspects deserve extra comment. The use of a subpectoral pocket makes the implantation less unsightly than a subcutaneous pocket.^ Perhaps more importantly, it adds another layer of protection against infection of the pacing system. If superficial infection occurs of the wound during healing after pacemaker implantation, it is much less likely to reach the pacemaker when it is in a subpectoral position then when it is in a subcutaneous position. If the punc-
November, Part n 1992
PACE, Vol. 15
PEDIATRIC PAGING
ture of the subclavian vein is also made below the pectoralis muscle, then this also applies to the leads. We have not had a pacemaker pocket infection in our group of patients with subpectoral implantation, and have not observed a lead fracture or damage in patients under 5 years old.^ In order to prevent problems with growth, we have left modest loops of lead in the right atrium in each patient with transvenous implantation. In addition, we have tied the suture around the suture sleeve with absorbable 2-0 suture. In this group of
patients under 5 years as well as our older group, there has been no need to push in leads during follow-up as long as 8 years. Although we occasionally find leads to have extended further into the heart at 6-week or 6-month follow-up, this has not caused clinical problems, such as premature beats or valve insufficiency. In summary, the results of this study show that transvenous and epicardial pacing may be performed in infants and children of any size with excellent results.
References 1. Smith RT Jr. Pacemakers for children. In PC Gillette, A Garson Jr (eds.): Pediatric Arrhythmias: Electrophysiology and Pacing. New York, NY, Grune and Stratton, 1990, pp. 532-558. 2. Gillette PC, Zeigler VL. Transvenous implantation technique. In PC Gillette, A Garson Jr (eds.): Pediatric Arrhythmias: Electrophysiology and Pacing. New York, NY, Grune and Stratton, 1990, pp. 559-574. 3. Ott DA. Epicardial pacemaker implantation. In PC Gillette, A Garson Jr (eds.): Pediatric Arrhythmias:
PACE, Vol. 15
Electrophysiology and Pacing. New York, NY, Grune and Stratton, 1990, pp. 575-579. Gillette PC, Edgerton J, Kratz JM, et al. The subpectoral pocket: The preferred implant site for pediatric pacemakers. PACE 1991; 14:1089-1092. Lau YR, Gillette PC, Buckles DS, et al. Actuarial survival of transvenous pacing leads in a pediatric population, (abstract) Presented at the 13th Annual Scientific Session of the North American Society of Pacing and Electrophysiology, May 14-16, 1992, Chicago, Illinois.
November, Part II 1992
2049
children < 5 years old at pacemaker implant were followed from 1 to 105 months. Five of 37 patients required reoperation for battery depletion while two required reoperation for exit block of epicardial ventricular leads. Each patient paced in the DDD or AAI mode was still in the original mode at the end of follow up. (PACE, VoJ. 15, November, Part II 1992) neonatal pacing, pediatric pacing, transvenous pacing
Introduction Cardiac pacing is being increasingly prescribed for neonates, infants, and young children.^ This is partially because physicians and other health care professionals who care for these children are more aware of potential symptomatic bradydysrhythmias and because cardiac surgery is being performed in smaller children with increasingly more complex cardiac defects. The techniques and results of cardiac pacing in adults and older children have been well described in the literature. We therefore, set out to review our experience with cardiac pacing in children < 5 years old over an 8-year period at the Medical University of South Carolina. Methods Data were collected from the records of the Pediatric Cardiac Pacemaker Clinic, as well as from the implant records of the operating room and cardiac catheterization laboratory of the South Carolina Children's Heart Center. The patient's outpatient charts and records of electrocardi-
Address for reprints: Paul C. Gillette, M.D., Medical LFniversity of South Carolina, South Carolina Children's Heart Center, 171 Ashley Avenue, Charleston, SC 29425. Fax: (803) 792-3284.
2046
ograms and Holter monitors were also reviewed. The patient's follow up in the Pediatric Pacemaker Clinic began immediately after implant and continued at 6 weeks, 6 months, and yearly thereafter. Transtelephonic follow up included weekly transmissions for the first 6 weeks, monthly transmissions for the rest of the first year, and 3-month transmissions thereafter. The patients were also instructed to send a telephone strip and voice message when concerned about the function of their pacing system, particularly after sustaining a physical trauma. Results Thirty-seven children had had implantation of a cardiac pacemaker at the Medical University of South Carolina before the age of 5 years. They ranged in age from 1 day to 57 months (mean = 23 months), and their weights ranged from 1.3 to 19.8 kg (mean = 10.3 kg). Their anatomical diagnosis showed that 14 had normal cardiovascular systems while 23 had had repairs of congenital heart defects (Table I). Their electrophysiological diagnosis are in Table II. The implantation technique was chosen according to the patient's characteristics.^ If an intracardiac shunt was present, an epicardial system was recommended. Patients under 5 kg w h o required a single lead received epicardial implants
November, Part II 1992
PACE, V o l . 15
PEDIATRIC PACING
Table I. Anatomical Diagnoses in Postoperative Children Requiring Permanent Pacing Senning/Mustard Septal defects Fontan Subaortic stenosis Complex CHD Cardiomyopathy
Table III. Pacing Mode
as well as patients under 10 kg who required dual chamber pacing. Other candidates for dual chamber implants were postoperative patients and patients with normal hearts but with depressed cardiac function. Using these criteria, 20 patients had endocardial and 17 had epicardial implantation. Pacemakers were carefully chosen to allow the pacing mode most appropriate to the patient's need. For example, patients who had atrial reentry tachycardia after repair of a transposition of the great arteries or a Fontan repair for a single ventricular complex, received a multiprogrammable atrial demand pacemaker capable of overdrive atrial pacing. Patients who had uncomplicated sinus bradycardia and who could be paced to an atrial rate of at least 120 without developing second-degree AV block, had implantation of an atrial demand pacemaker. Patients, who had complete AV block or high grade AV block, received dual chamber pacemakers initially programmed to the DDD mode. Patients, who had transient AV block but were considered to be at risk of sudden death or at risk of increase in degree of AV block, received ventricular demand pacemakers. Three pa-
Table II. Pacing Indications in Children < 5 Years of Age Congenital AV block Acquired AV block Electrical cardiomyopathy Sinus node dysfunction Atrial R/E tachycardia + sinus node dysfunction Others
PACE, Vol. 15
AAI VVI DDD
4 12 3 t 2 t
9 15 2 5 4 2
AAICP VVIR
3 13 14 4 3
tients had a ventricular demand rate responsive pacemaker implanted because no more than one lead could be introduced into the subclavian vein. Table III shows the pacing mode selected for the various patients. The pacemakers were selected very carefully for size and functionality. Because of these patients' very young age and small size, the smallest pacemaker available was chosen while providing the most possible programmability to meet the expected changing needs of this very young patient population. Implant Technique
Transvenous implantations were performed in the cardiac catheterization laboratory. A venous angiogram was performed to determine the anatomy of the subclavian vein and its suitability for positioning of the pacemaker lead. The angiographic catheter was left in the left subclavian vein to be used as a target during needle entry into the subclavian vein. The most common lead used was a bipolar, silicone insulated, screw-in, porous tipped electrode. More recently, a mannitolcoated lead has been used to facilitate manipulation across the tricuspid valve. A curved stylet was used to help the lead cross the tricuspid valve and approach the ventricular septum approximately one third of the way from the apex to the pulmonary valve. Therightventricular apex was avoided as a lead position because of possible pacing of the diaphragm. The atrial lead was screwed at the base of the right atrial appendage or other positions as necessary if the base of the right atrial appendage failed to give adequate signals or pacing thresholds. The leads were positioned further into the heart to try to leave small loops for growth. Large loops were not sought since it was felt that they
November, Part II 1992
2047
GILLETTE, ET AL.
might cause extrasystoles. The leads were sutured down at the subclavian puncture site, the pacemaker was interfaced and positioned in the subpectoral pocket, and telemetry testing of the entire pacing system was performed using a sterile programming wand. The muscle layer was then closed with 2-0 absorbable suture, as was the subcutaneous tissue, and the skin was approximated using a 4-0 absorbable suture and steri-strips. Epicardial Implant Technique The patients who received epicardial pacemakers had their implants in the operating room by a cardiovascular surgeon.^ Except for five patients in this series, myocardial stab-on or screwin leads were used. For the most part, screw-in leads with a 2H turn screw were used in the ventricle, whereas stab-on leads were used in the atrium. A few patients had a stab-on lead positioned in the ventricle and in the atrium. Five patients had implantation of an investigational steroid epicardial lead or leads that had no screw or barb. It was sutured to the myocardium using three suture holes and a plaque electrode affixed to the myocardium. Follow Up Implants were successfully completed in each patient. One patient died within 24 hours of pacemaker implantation of progressive preexisting congestive heart failure and respiratory failure. Seven patients died during follow up of congestive heart failure. None died suddenly and in none was the pacing system considered to have contributed to the death. Two patients were reoperated for epicardial ventricular lead problems. These were corrected by electively intervening when the output of the pulse generator had to be programmed at 8 V/1 msec. In both cases, the lead was replaced by a steroid epicardial ventricular lead. In one case, the threshold remained low over 1 year of follow up. In the other case, threshold rose again within months, and an endocardial steroid ventricular lead was substituted. Five patients underwent reoperation for replacements of epicardial units that had been programmed at relatively high output in order to keep an adequate safety margin for pacing. All patients who had two leads implanted are cur-
2048
rently paced in the DDD or DDI mode. All atrial leads are still functioning. Discussion Cardiac pacing has been used with increasing frequency in neonates, infants, and small children. This report demonstrates that it can be used safely and efficaciously. There is a trend towards using more and more transvenous units, which is justified since reoperations were necessary in two patients with epicardial leads. In addition, tke need for high pulse generator outputs in the epicardial group caused earlier battery depletion. Therefore, it seems justified to continue to attempt transvenous implantations in smaller and smaller children as techniques, lead sizes, and pacemaker sizes evolve. In order to perform this procedure safely, a dedicated catheterization laboratory experienced in catheterizing neonates as well as in performing electrophysiological studies and pacemaker implants is necessary. In addition, we have found the use of general anesthesia useful in infants under 1 year of age. Epicardial techniques have also improved considerably, and the size a dual chamber pacemaker is now the same as that of a single chamber device except for an extra lead header. Thus, if myocardial function is abnormal, or if there is a congenital cardiac defect, we recommend the implantation of a dual chamber pacemaker, even in neonates. The stab-on lead has recently been platinized, resulting in lower pacing thresholds, and the recent clinical trials with the steroid epicardial lead have been promising. There are still problems with fibrous adhesions from previous heart surgery. The implantation of the steroid sew-on epicardial lead is more difficult than the stab-on or screw-in systems, but lower pacing thresholds make the extra effort worthwhile. Other technical aspects deserve extra comment. The use of a subpectoral pocket makes the implantation less unsightly than a subcutaneous pocket.^ Perhaps more importantly, it adds another layer of protection against infection of the pacing system. If superficial infection occurs of the wound during healing after pacemaker implantation, it is much less likely to reach the pacemaker when it is in a subpectoral position then when it is in a subcutaneous position. If the punc-
November, Part n 1992
PACE, Vol. 15
PEDIATRIC PAGING
ture of the subclavian vein is also made below the pectoralis muscle, then this also applies to the leads. We have not had a pacemaker pocket infection in our group of patients with subpectoral implantation, and have not observed a lead fracture or damage in patients under 5 years old.^ In order to prevent problems with growth, we have left modest loops of lead in the right atrium in each patient with transvenous implantation. In addition, we have tied the suture around the suture sleeve with absorbable 2-0 suture. In this group of
patients under 5 years as well as our older group, there has been no need to push in leads during follow-up as long as 8 years. Although we occasionally find leads to have extended further into the heart at 6-week or 6-month follow-up, this has not caused clinical problems, such as premature beats or valve insufficiency. In summary, the results of this study show that transvenous and epicardial pacing may be performed in infants and children of any size with excellent results.
References 1. Smith RT Jr. Pacemakers for children. In PC Gillette, A Garson Jr (eds.): Pediatric Arrhythmias: Electrophysiology and Pacing. New York, NY, Grune and Stratton, 1990, pp. 532-558. 2. Gillette PC, Zeigler VL. Transvenous implantation technique. In PC Gillette, A Garson Jr (eds.): Pediatric Arrhythmias: Electrophysiology and Pacing. New York, NY, Grune and Stratton, 1990, pp. 559-574. 3. Ott DA. Epicardial pacemaker implantation. In PC Gillette, A Garson Jr (eds.): Pediatric Arrhythmias:
PACE, Vol. 15
Electrophysiology and Pacing. New York, NY, Grune and Stratton, 1990, pp. 575-579. Gillette PC, Edgerton J, Kratz JM, et al. The subpectoral pocket: The preferred implant site for pediatric pacemakers. PACE 1991; 14:1089-1092. Lau YR, Gillette PC, Buckles DS, et al. Actuarial survival of transvenous pacing leads in a pediatric population, (abstract) Presented at the 13th Annual Scientific Session of the North American Society of Pacing and Electrophysiology, May 14-16, 1992, Chicago, Illinois.
November, Part II 1992
2049
