Permanent cardiac pacemakers in children: technical considerations

The Southern Thoracic Surgical Association 50th anniversary celebration: the impact of STSA pediatric cardiothoracic surgery manuscripts on surgical practice

BACKGROUND

Members of the Southern Thoracic Surgical Association (STSA) have presented important pediatric cardiothoracic surgery papers at the annual meetings over the last 50 years. In order to determine the influence of these presentations on the practice of surgery, a review was undertaken. Early papers were characterized by emerging advances in open-heart surgery, anatomic congenital heart studies, and electrophysiologic discoveries that extended life with pacemakers. Later years were characterized by innovative myocardial preservation methods, improved cardiopulmonary bypass techniques, expanded homograft availability, emphasis on accurate repairs, intraoperative transesophageal echocardiography, and cardiopulmonary transplantation.

METHODS

All but one of the scientific programs of the annual meetings (that of 1964) were located. The programs were reviewed and 180 presentations were identified on topics in congenital heart disease, pediatric thoracic disease, and pediatric thoracic wall abnormalities. Of those 180 oral presentations, 155 manuscripts (86%) were eventually published or in press and available for critical review and analysis. Manuscripts were grouped by diagnosis or therapeutic intervention. We determined a "cumulative citation frequency" (CCF), which measures the number of times an article is cited in the bibliography of related papers in the universe of participating journals. The selected manuscripts were compared with the historic landmark contributions and the existing trends at the time, and the number of articles both by individual authors and from institutions were tallied.

RESULTS

Grouping by authors and institutions showed that 100 of 155 pediatric cardiothoracic manuscripts (65%) originated from 13 institutions. The CCF for the 20 leading articles ranged from 26 to 93.

CONCLUSIONS

This historical STSA 50-year record of pediatric cardiothoracic advances was accomplished in a milieu of collegial respect and camaraderie. Our annual meetings over the years have provided a venue for thoracic surgeons to share their ideas, innovations, and scientific inquiry. These contributions have significantly affected the practice of pediatric cardiothoracic surgery. The STSA has worked for 50 years and we trust that it will work for another 50 years and beyond.

Permanent pacemaker implantation in premature infants less than 2,000 grams of body weight

Pacemaker implantation in premature infants presents technical problems because of the relatively larger size of the pulse generator compared with their bodies. A new technique with which successful generator implantation was performed in 2 premature infants less than 2,000 g of body weight is described. The generator is wrapped in a Gore-Tex surgical membrane. A piece of membrane overlying the electrical contact surface of the generator is removed, and the generator is fixed to the abdominal wall in the peritoneal cavity. The technique is simple to perform and would give relative ease in generator exchange.

Pacemakers in children: an update

This report reviews recent pacemaker technological advances as they apply to infants, children, and adolescents. Indications for pacemaker implantation in children have evolved since the 1984 Joint Task Force Guidelines. Recent data show that pacemaker implantation should be strongly considered in patients who have (1) asymptomatic congenital complete AV block with a mean heart rate less than 50 beats/min or other evidence of junctional instability; (2) congenital AV block with long QT interval; or (3) congenital long QT syndrome with bradyarrhythmias, or when conventional beta-blocker therapy is unsuccessful. Permanent pacemaker implantation is not necessarily an effective prophylactic measure against sudden death in patients following their operation who are receiving drug therapy for atrial tachyarrhythmias, and so is not absolutely indicated. New developments in lead technology have made transvenous lead systems more feasible for pediatric use. Because epicardial leads are required for small infants and for cosmetic reasons in some older children, design improvements are needed to enhance epicardial lead performance. Rate-responsive pacing is an acceptable alternative to dual-chamber pacing for augmenting exercise tolerance, and for children with sinus node dysfunction it is the preferred pacing mode. Pacemakers with automatic antitachycardia capabilities and with noninvasive electrophysiology features are valuable in children with atrial tachyarrhythmias. New data suggest that chronic atrial pacing also may be effective in controlling atrial tachyarrhythmias. New developments in pacemaker systems for the young parallel those for the older population, but differences between adult and pediatric patients demand ongoing increased participation by pediatric cardiologists.

A new technique for permanent pacemaker implantation in infants and children

Permanent pacemaker implantation in the infant or young child presents the surgeon with many technical problems unique to this population. A new technique of implantation is described that was used successfully in 6 pediatric patients. The technique is simple to perform and gives very satisfactory results.

Permanent pacemaker therapy in corrected transposition of the great arteries: analysis of site of lead placement in 40 patients

A retrospective analysis of 58 pacemaker leads in 40 patients with corrected transposition of the great arteries (CTGA) was made to compare the function of endocardial and epicardial leads. Extensive trabeculations of the normal right ventricle are generally thought to be essential for endocardial pacemaker lead stability. Because the systemic venous ventricle in CTGA lacks an extensive trabecular network, there has been concern that transvenous lead placement may result in a high rate of dislodgement. Epicardial leads have been assumed to be more reliable in these patients. Forty-seven epicardial and 11 endocardial leads were placed in 40 patients with CTGA who required permanent pacemaker therapy for symptomatic bradycardia. Of 13 episodes of epicardial lead malfunction in 158 patient-years, 3 were due to lead fracture and 10 to high thresholds. Surgery was required to correct the lead malfunction in 12 instances and thoracotomy was necessary for new lead placement in 6 patients. During 26.2 patient-years, there were 2 episodes of endocardial lead failure due to a high acute threshold and perforation. There were no instances of endocardial lead dislodgement. No association between type of failure and lead design was noted for either endocardial or epicardial leads. Actuarial analysis of survival revealed no significant differences in reliability between endocardial and epicardial leads. Endocardial lead fixation in the systemic venous ventricle in patients with CTGA is adequate to prevent lead dislodgement and preferable to epicardial lead placement because thoracotomy is avoided.

Epicardial corkscrew lead fracture: an underreported cause of pacing failure?

Three children with a pacemaker sustained similar lead fractures within a two-year period. Each fracture occurred in the corkscrew portion of a Medtronic Model 6917 epicardial lead. All patients were boys. The leads had been in place for 12, 45, and 43 months prior to fracture. None of the patients had sustained major trauma. Fracture of the corkscrew lead has been considered an uncommon complication. However, three lead fractures in the corkscrew area in a population of 60 children followed at this institution indicate that this may be a more common cause of pacemaker-system malfunction than previous data suggest. A plea is made for reporting all pacing failure to the manufacturer.

Electrophysiologic residua and sequelae of surgery for congenital heart defects

Postoperative arrhythmias may occur in any patient who undergoes intracardiac surgery for a congenital heart defect. The correction of certain intracardiac heart defects predisposes to a large incidence of cardiac arrhythmias. Ventricular arrhythmias and conduction disturbances are seen after correction of tetralogy of Fallot, ventricular septal defect and atrioventricular canal defect. Supraventricular arrhythmias and sinus nodal dysfunction may be seen after surgery for transposition of the great arteries or atrial septal defect. The identification, evaluation and treatment of these patients are discussed.

Long-term endocardial atrial pacing in children with postoperative bradycardia-tachycardia syndrome and limited ventricular access

Permanent pacing in children, including those with postoperative bradycardia-tachycardia syndrome has been compromised by the availability of pulse generators, electrode leads and implantation techniques designed for the adult patient. Recent technologic improvements and simplified implantation techniques have reduced many of these barriers and have made endocardial as well as epicardial ventricular pacing more feasible. However, in some children, ventricular pacing may be impeded by anatomic abnormalities due to congenital anomalies or prior cardiac operations. In these instances, endocardial atrial pacing may provide an alternative therapeutic approach in selected patients. This report describes the use of endocardial atrial demand pacing in four children with postoperatively bradycardia-tachycardia syndrome and restricted ventricular access. This approach controls symptomatic bradycardia, helps prevent and convert paroxysmal intraatrial tachycardia and overcomes the problems of limited ventricular access.

Changing indications for pacemakers in children

Permanent pacemakers were implanted in 50 children. Indications were symptomatic sinus node dysfunction in 34 (68%), surgical block in 9 (18%), and congenital block in 7 (14%). Twenty-three (68%) of the 34 children with sinus node dysfunction had undergone prior cardiac operations. Only 4 of the 50 patients (8%) had electrode problems after a mean pacing time of 29.5 months (range, 1 to 96 months). All 35 of the mercury-cell pulse generators used in 28 patients ceased to function after an average useful life of 20.8 months (range, 1 to 51 months). The lithium-powered units in the 45 survivors all show satisfactory pacing after 5 to 44 months (mean, 28.1 months). With improved pacemaker technology, longer survival after complex repairs, and better monitoring techniques, the indications for cardiac pacing in children have broadened. Surgical block now is an indication in only a small fraction of the pediatric pacemaker population. Sinus node dysfunction accounts for an ever-increasing majority of the pacemakers we currently implant in children.

Pacemaker implantation in infants and children: a simplified approach

A technique for epicardial pacemaker implantation is described. A single incision is utilized through which the electrode and power pack are implanted. Twelve infants and children were operated on in the last four years using this procedure. The marked improvement in cosmetic appearance and the relative ease in module replacement are major advantages of this method.

The recessed chest wall pacemaker pocket

Recurrent pouch problems led to the development of a recessed chest wall pacemaker pocket. Segments of the seventh and eighth ribs were resected in the mid-axillary line resulting in a "tailor-made" space suitable for generator implantation. Follow-up at one year has proven the chest wall to be a satisfactory alternative site for a pacemaker pocket.

Permanent cardiac pacing in infants and children

This clinical review details our 15 year experience with permanent cardiac pacemakers in 81 infants and children. Pacing was found inappropriate in one infant. The other 80 patients were paced because of congenital heart block [24], post-operative block [50], or sick sinus syndrome [6]. Maintenance of long-term pacing requires all too frequent re-operation for battery depletion [37%], lead related problems [32%] or wound dehiscence [31%]. Problems related to pacemaker size and the presence of a high myocardial threshold are particularly important in the pediatric patient. In spite of these problems, children requiring cardiac pacemakers can be extremely well, their prognosis depending almost entirely on the presence of underlying heart disease.

Pacemakers in young patients: 1977

Recent experience with implanted cardiac pacemakers in nine young patients is reported. Advance in technology include improved pacemaker generator design and placement, and improved lead design and placement. No patients died; our only complication, failure to capture, required repositioning of the lead. All pacemaker replacements were elective. This series helps to define the more favorable current prognosis for the young patient needing pacemaker therapy.

Intermuscular abdominal implantation of permanent pacemakers in infants and children

Pacemaker implantation in infants and young children presents technical problems because of the relatively large size of the units. Various implantation sites have been employed to avoid the problems of unsightliness, migration, skin necrosis with infection, and patient discomfort. We are presenting a new technique which obviates these difficulties. The pacemaker generator is located in a space developed between the muscles and fascia of the abdominal wall. This site will accept even the largest of demand pacemakers with cosmetically acceptable results.

Fourteen years of implanted pacemakers in children

Twenty-six children who had permanent pacemakers implanted at 6 hours to 11 years of age have been followed for up to 163 months. There were 14 children with surgical heart block, 9 with congenital heart block, 2 with postcatheterization complete heart block, and 1 with bradytachydysrhythmia syndrome. Eighteen of the 26 patients (69%) are still being paced with their original electrodes, some for more than eight years. Sixty pulse generators lasted an average of 17 months (range, 1 to 55 months). Five of the 26 patients (19%) are dead. Three died of noncorrectable heart disease, but there were 2 sudden unexplained deaths at home, both apparently due to sudden arrhtthmias. Both of these patients had received fixed-rate pulse generators, and 1 had a known potential for competing rhythms. The current optimal choices of equipment and techniques, including the role of synchronized, demand, lithium-powered, and nuclear-powered pulse generators, are discussed.

Cardiac pacing in children and adolescents

Nineteen patients aged 1 month to 18 years underwent implantation of a cardiac pacemaker and were followed up for up to 9 years (average duration of pacing 54 months). Complete heart block was present in 16 patients and sinus nodal dysfunction in 3. Heart block was presumably of congenital orgin in eight, secendary to cardiac surgery in seven and subsequent to cardiac catheterization in one. Sinus nodal dysfunction was of presumed congenital origin in one and occurred after cardiac surgery in two. Pacing was required because of syncopal attacks in eight patients, three of whom had congestive heart failure or low cardiac output on physiologic studies. It was required in four because of congestive heart failure, in two because of low cardiac output (one with a wide QRS complex), and in five for postoperative rhythm control. With return of sinus rhythm after 2 and 3 months, respectively, pacing was discontinued in two patients. One child was partially corrected disease died within 3 months, one died of wound breakdown and sepsis after 10 months of pacing and one died suddenly 4 years after implantation. All others have returned to normal activity; only one requires cardiac medication. The degree of emotional stability has been striking. Asynchronous and atrial synchronous pacing are of equal therapeutic value. The very small radiofrequency implanted receiver has been useful in younger children. The major problems have been caused by the large size and short longevity of the generators and the child's growth stressing the lead system. Transvenously implanted pacemakers have presented no greater management problems than those placed during thoracotomy.