Implantable Pacemakers
in Children
Joseph
D. Marco, MD; John E. Codd, MD; Hendrick B. Barner, MD; Barbara S. Czerwinski, RN; George C. Kaiser, MD
Permanent pacemakers were implanted in 12 children, ages 2 weeks to 6 years. The cause of the arrhythmia was congenital in three, postoperative in six, viral in one, and unknown in two. One operative death occurred on the second postoperative day. Two late deaths occurred five and 10\m=1/2\years postoperatively. The late deaths were in patients with good cardiac capture in whom the block followed repair of tetralogy of Fallot. Ventricular arrhythmias were believed to be the cause of death. Reoperation was required 37 times: for pacemaker exhaustion, 17; electrode problems, 15; wound problems, four; and arrhythmia, one. Nine of 12 patients are alive nine months to ten years eight months postoperatively. The remaining three survived for eight to ten years. Frequent reoperation and diligent correction of defective pacing is rewarded with long, active lives in children requiring implantable pacemakers.
block, generally Heartdisease, entity
associated with degenerative of the elderly that is well man¬ aged with permanent pacemakers.12 Implantable pace¬ makers are infrequently employed in childhood, but are occasionally used in the treatment of congenital and post¬ operative heart block.3,4 is
able block in one child; this following repair of transposition of the great vessels, and atrial and ventricular septal defects (VSD)
(Table).
All but one patient with a nonoperative cause of arrhythmia ex¬ perienced syncope as the indication for pacing. The exception was a 15-day-old infant with congenital heart block who developed poor cardiac output and cyanosis during periods of bradycardia. None of the patients with traumatic bradycardia had syncope in the interval between surgery and the institution of pacing. The technique of initial electrode insertion was transthoracic, epicardial in all instances. Two had subsequent permanent transvenous electrodes. Ventricular asynchronous impulse generators were initially employed in seven, atrial synchronous in three, and
demand in two. Reoperation has been required 37 times. One patient has re¬ quired 12, another eight, and a third six operations. Thirty-eight impulse generators have been used; 12 initially and 17 for impulse generator failure. Nine others were changed electively at the time of operation for other reasons.
an
PATIENTS AND METHODS From July 6, 1964, to the present we have treated 12 children, four girls and eight boys, with bradycardia by permanent pace¬ maker implantation. Their ages at initial implantation ranged from 15 days to 16 years (Table). The cause of the rhythm disturbance was congenital in three and acquired in nine; of the latter, six were traumatic (operative). The basic rhythm was complete heart block in nine, intermittent block in two, and intermittent bradycardia-tachycardia with vari-
Accepted for publication March 27, 1975. From the Department of Surgery, St.
Louis University, School of Medicine. Read before the 32nd annual meeting of the Central Surgical Association, Chicago, Feb 27, 1975. Reprint requests to 1325 S Grand Ave, St. Louis, MO 63104 (Dr. Kaiser).
RESULTS
All patients have been followed up since implantation for an average of 4M years (range, nine months to 11 years). The one early death occurred in a 15-day-old boy on the second postoperative day from low cardiac output. There were two sudden late deaths, one in an 11-year-old boy five years after initial pacemaker insertion with heart block following repair of a right ventricular aneurysm and recurrent VSD, and the other in a 17y2-year-old boy lOVé years after initiation of pacing for postoperative heart block from repair of tetralogy of Fallot. In both instances, the boys had led very active lives and were verified as pac¬ ing well within a few days of death. In both instances, postmortem electrocardiograms showed electrically satis¬ factory pacemaker function and in one roentgenogram as¬ sured integrity of the leads. One was known to have fre¬ quent ventricular arrhythmias. Impulse generator failure was the most common indica¬ tion for reoperation. In these 12 patients, a total of 38 im-
Downloaded From: http://archsurg.jamanetwork.com/ by a Oakland University User on 06/10/2015
Clinical Data Patient
Date of
Age 5V2 yr
Implantation 7/6/64
6 yr
7/13/64
7yr
8/26/64
16 yr
5/6/66
No. of
Rhythm
Operative
Associated Disease Tetralogy of Fallot
Operative
Tetralogy of Fallot
Operative
Tetralogy of Fallot
& Heart Block
Permanent
Third-degree Permanent
Third-degree Permanent
Third-degree
Cause
Permanent
Third-degree
Congenital
9V2 yr*
7/29/70
Permanent
Operative
12V2yr
8/20/71
Permanent
17
4/25/72
Permanent
3yr
7/10/72
4 yr
8/1/72
mo
10 yr 6
mof
2
Variable Second- 8 third-degree
mo
10 yr 7
8yr 9
6/24/69
Third-degree
Third-degree
12
Time Paced 5 yr 1 mof
Idiopathic
days
15
Operations
Operative
Endocardial cushion defect Tetralogy of Fallot
mo
dayst
4 yr 7
mo
3 yr 6
mo
Congenital
2 yr 10
Permanent
Viral"
2 yr 7 mo
Third-degree Bradycardia-tachycardia
Operative
Third-degree
Transposition great vessels, atrial and ventricular septal
2 yr 6
mo
mo
defects
yr*
6/19/73
4V2 yr*
5/24/74
16
*
Variable First- & second-degree Permanent
Third-degree
Idiopathic
1 yr 8 mo
Congenital
9 mo
Girls.
t Deaths.
pulse generators were inserted, 30 asynchronous, six atrial synchronous, and two demand. The median time of gener¬ ator failure was 29.5 months for asynchronous pacemakers and 22.5 months for atrial synchronous pacemakers. Atrial synchronous or demand pacemakers were used in those patients with variable block. In no patient is atrial syn¬ chronous pacing currently in effect as atrial synchrony has failed in all, presumably due to decreased atrial voltage. Electrode fracture, the second most common indication for reoperation, occurred on 11 occasions in four patients. It occurred four times in one patient, three times in an¬ other, and on two occasions in each of the two other pa¬ tients. It has not been shown as a cause of sudden death in any of our patients and we have not attempted to limit
activity.
Stimulation threshold increase or exit block occurred on four occasions in two patients. In both, the myocardial electrodes had been inserted into the right ventricle in which a ventriculotomy had been done for repair for VSD. Both hearts were subsequently well captured by perma¬ nent transvenous electrodes at low thresholds. One of these later had conversion to left ventricular epicardial electrodes when the impulse generator was replaced for rate change. Positioning of this patient could precipitate intermittent cardiac capture. It was noted by roentgen¬ ogram that the electrode had withdrawn slightly from the
heart, secondary
to
growth.
Wound erosion occurred on three occasions and infec¬ tion in one patient required reoperation. Erosion was treated by revision of the impulse generator pocket or, as
with the two infected tion.
pockets, placement in
another loca¬
COMMENT
Impulse generator failure is the most frequent indica¬ pacemaker reoperation. This is principally due to battery exhaustion and secondarily to electronic failure.7' Our experience confirms that power source failure in chil¬ dren, as in adults, is the most frequent reason for reopera¬ tions.1 Impulse generator failure carries with it the theo¬ retical implication of sudden death, but most failures occur gradually and are easily detected and corrected by appropriate monitoring of patients. Reoperation carries with it the practical potential for infection each time the pacemaker system is manipulated. Any technique to re¬ duce the number of reoperations should reduce this haz¬ ard. Improved energy sources with greater longevity tion for
strive toward this end.68 Other methods to conserve energy have involved decreasing pacemaker output or pulse duration. Telephone surveillance systems have ex¬ tended the time conventional power sources can safely and effectively be left in place.5-9 While many of the el¬ derly will not need improved power sources because their longevity is influenced by complications of other diseases, children should potentially benefit from these improve¬ ments.
Electrode fracture, the second most common indication for reoperation in our children, is observed infrequently in adult patients.12 The fact that electrode fracture occurred only in the boys suggests that increased physical activity
Downloaded From: http://archsurg.jamanetwork.com/ by a Oakland University User on 06/10/2015
is related. These children engaged in normal, vigorous ac¬ tivities limited only be exclusion from organized, competi¬ tive or contact sports. Retroperitoneal pacemaker and electrode placement or having the leads exit through the diaphragm, to avoid angulation over the ribs or costal margin, might be helpful in reducing lead fractures. The relatively large pacemaker size has stimulated ef¬ forts in chosing the best location for impulse generator placement in the smaller child.310 In two instances, we have resorted to retroperitoneal impulse generator place¬ ment behind the left iliac crest in attempts to avoid skin erosion and injury to the electrode. The use of atrial synchronous pacemakers in children has been advocated by some as the ideal pacing mode.2 Our experience is at variance with this. In no instance is any patient currently being paced with atrial synchrony. All survivors have been converted to fixed-rate pacing for lack of atrial synchrony. While the theoretical advantages of atrial synchronous pacing have been extensively dis¬ cussed, for practical purposes asynchronous pacing in chil¬ dren has been associated with normal growth and develop¬ ment and has not impaired physical activity. Late sudden death occurred in two boys with complete heart block following repair of tetralogy of Fallot, five
and 10% years after institution of pacing. Pacemaker function was satisfactory in both by postmortem ECGs. The one child had been noted to have episodes of ventricu¬ lar irritability including ventricular tachycardia requiring defibrillation beginning nine years after pacing. It is notable that late sudden deaths, attributable to arrhyth¬ mias, in otherwise healthy patients following successful repair of tetralogy of Fallot have become more widely rec¬ ognized.11·12 In view of the similarity of the deaths and the clinical courses of these two patients, it is highly proba¬ ble that sudden ventricular arrhythmias were the cause of death in both instances. CONCLUSION From this experience it is apparent that asynchronous cardiac pacing has been effective in permitting unre¬ stricted activity along with normal growth and develop¬ ment in a group of children. The paced child requires vigorous surveillance for generator function and lead con¬ tinuity, but with close attention and repeated adjust¬ ments of the hardware, long-term survival with normal growth and development is attainable. Improved gener¬ ator reliability and longevity should strikingly improve the course of this group of patients.
References 1. Kaiser GC, Barner HB, Willman VL, et al: Surgical treatment of bradycardia. Arch Surg 98:612-618, 1969. 2. Stoney WS, William CA, Burrus GR, et al: Complications of long-term pacing. Read before the 21st annual meeting of the Southern Thoracic Surgical Association, Williamsburg, Va, 1974. 3. Lindesmith GG, Stiles QR, Meyer BW, et al: Experience with an implantable synchronous pacemaker in children. Ann Thorac Surg 6:358-364,
1968. 4. Daicoff GR, Aslami A, Tobias JA, et al: Management of postoperative complete heart block in infants and children. Chest 66:639-641, 1974. 5. Furman S: Transtelephone pacemaker monitoring: Five years later. Read before the 11th annual meeting of the Society of Thoracic Surgeons, Montreal, 1975. 6. Huffman FN, Norman JC: Nuclear-fueled cardiac pacemakers. Chest 65:667-672, 1974.
7. Lillehei RC, Romero LH, Beckman CB, et al: A new solid-state, long\x=req-\ life, lithium-powered pulse generator. Ann Thorac Surg 18:479-489, 1974. 8. Lewis KB, Criley JM, Nelson RJ, et al: Early clinical experience with the rechargeable cardiac pacemaker. Ann Thorac Surg 18:490-493, 1974. 9. Goldman BS, Heller JG, Noble EJ, et al: Critical analysis of pulse generator replacement. Ann Thorac Surg 18:156-163, 1974. 10. Williams GD, Campbell GS: Pacemaker installation in the pediatric patient: An improved technique. Surgery 66:412-414, 1969. 11. James FW, Kaplan S: Sudden unexpected cardiac arrest in patients after surgical correction for tetralogy of Fallot. Am J Cardiol 35:146,1975. 12. Quattlebaum TG, Varghese PJ, Neill CA, et al: Sudden death among postoperative patients with tetralogy of Fallot: A follow-up study of 251 patients for an average of 12 years. Am J Cardiol 35:164, 1975. 13. Bairan AC, Cherry JD, Fagan LF, et al: Complete heart block and respiratory syncytial virus. Am J Dis Child 127:264-265, 1974.
Discussion James W. Kilman, MD, Columbus, Ohio: I would like to con¬ group on bringing to our attention a problem that those of us who work in pediatrie cardiovascular surgery realize exists and yet one we do not think about too often. I was asked to discuss this paper and, as a result, looked up our own series of pacemakers in children; interestingly enough, we have had 12 children requiring pacemakers at the Columbus Chil¬ dren's Hospital of Ohio State University. Our problems have been quite similar to those the group pre¬ sented here. We do not have as good a follow-up, and maybe it in¬ dicates that the children in Columbus are a little more active than those in St. Louis, but we have had more wire fractures, and we have had five patients die. More and more is being learned about the postoperative results of the tetralogy of Fallot and from real¬ izing that these children do die from ventricular arrhythmias that occur after repair of the VSD in tetralogy. Some good studies in Cincinnati, by Dr. Kaplan and his group, have shown that if one does very careful studies the Fallot pa¬ tients have a very high incidence of ventricular arrhythmias. So, I think these deaths are probably a combination of failure of the
gratulate the
pacemaker systems and the natural history of the disease. Our recent indications show that we have not been required to put a pacemaker in for an acquired surgical block since 1969, but recently we have implanted one for Ebstein anomaly following to¬ tal repair and one in an attempt to improve a block acquired from viral myocardiopathy and for congenital block. I have two questions I would like to ask the authors: What in¬ formation do they have concerning sensing problems in the longterm use of pacemakers? We are running into this more and more often in our adult population with long-term use of pacemakers, particularly in the postoperative patient who has fibrosis, both endocardial and epicardial. Johann L. Ehrenhaft, MD, Iowa City: I enjoyed Dr. Marco's paper very much. This is a most difficult problem. The children who have rhythm disturbances and heart block at birth are a really troublesome group of patients. Most get along for a while, but some will have some heart failure early. We pres¬ ently have no pacemakers and leads that could be adequately min¬ iaturized for use in infants. The reports of placements of pace¬ makers in infants have been very sporadic.
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In the group of children who have atrioventricular dissociations
following cardiac operations, the incidence is now very low, the placement of pacemakers is often very necessary because they do not survive prolonged periods of atrioventricular block without Stokes-Adams attacks and other problems. The real dilemma is which patients to treat with pacemaker im¬ plants; very rigid criteria should be adopted before this group of patients is condemned to the lifelong problems of being pace¬ maker-dependent. I wish the authors would say more about the make of pacemak¬ ers, the mode of implantation, and the systems used, either stan¬ dard, lithium, or atomic. Our experience in about the same number of patients has been very difficult due to the frequence of change of the battery packs, frequent problems with electrode repair, and breakage and wound problems. Second, what exact system would they prefer and advise the young surgeon to put in today if he is faced with a block after the repair of a VSD or tetralogy of Fallot? Dr. Kaiser: Dr. Kilman, we have not had too much of a sensing problem with demand units in children. We have had problems with atrial pacing, and we believe this adds very little long-term, as it ceases to function after a period of time. We used atrial syn¬ chronous pacing infrequently. We have seen two instances of so-
called entrance block in adults who have failed to sense, and sup¬ press, a demand unit, both with epicardial electrodes. Dr. Ehrenhaft, no patient with congenital heart block has re¬ ceived a pacemaker unless he has become symptomatic. With con¬ genital heart block we consider symptoms necessary before in¬ serting a pacemaker. The reason most patients with permanent block following operation are not symptomatic is that with per¬ sistent postoperative block, we do not wait for symptoms to occur before inserting a permanent pacemaker. It has been well shown that epicardial electrodes are better. They maintain a lower threshold for a longer period of time. Cer¬ tainly the required operation, a thoracotomy, is well tolerated in children. This would be our preference for the lead system. We have had experience with pacemakers of three or four manufac¬ turers and usually employ asynchronous and, more rarely, demand
pacemakers.
There are techniques currently available to increase the life of the standard power source, such as reducing the pulse width, or the output of the pacemaker. We have had no experience with lith¬ ium batteries, but plan to insert atomic units, particularly in this group of patients who have potential for such long lives. This is one aspect which should be most helpful in the future manage¬ ment of these patients.
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in Children
Joseph
D. Marco, MD; John E. Codd, MD; Hendrick B. Barner, MD; Barbara S. Czerwinski, RN; George C. Kaiser, MD
Permanent pacemakers were implanted in 12 children, ages 2 weeks to 6 years. The cause of the arrhythmia was congenital in three, postoperative in six, viral in one, and unknown in two. One operative death occurred on the second postoperative day. Two late deaths occurred five and 10\m=1/2\years postoperatively. The late deaths were in patients with good cardiac capture in whom the block followed repair of tetralogy of Fallot. Ventricular arrhythmias were believed to be the cause of death. Reoperation was required 37 times: for pacemaker exhaustion, 17; electrode problems, 15; wound problems, four; and arrhythmia, one. Nine of 12 patients are alive nine months to ten years eight months postoperatively. The remaining three survived for eight to ten years. Frequent reoperation and diligent correction of defective pacing is rewarded with long, active lives in children requiring implantable pacemakers.
block, generally Heartdisease, entity
associated with degenerative of the elderly that is well man¬ aged with permanent pacemakers.12 Implantable pace¬ makers are infrequently employed in childhood, but are occasionally used in the treatment of congenital and post¬ operative heart block.3,4 is
able block in one child; this following repair of transposition of the great vessels, and atrial and ventricular septal defects (VSD)
(Table).
All but one patient with a nonoperative cause of arrhythmia ex¬ perienced syncope as the indication for pacing. The exception was a 15-day-old infant with congenital heart block who developed poor cardiac output and cyanosis during periods of bradycardia. None of the patients with traumatic bradycardia had syncope in the interval between surgery and the institution of pacing. The technique of initial electrode insertion was transthoracic, epicardial in all instances. Two had subsequent permanent transvenous electrodes. Ventricular asynchronous impulse generators were initially employed in seven, atrial synchronous in three, and
demand in two. Reoperation has been required 37 times. One patient has re¬ quired 12, another eight, and a third six operations. Thirty-eight impulse generators have been used; 12 initially and 17 for impulse generator failure. Nine others were changed electively at the time of operation for other reasons.
an
PATIENTS AND METHODS From July 6, 1964, to the present we have treated 12 children, four girls and eight boys, with bradycardia by permanent pace¬ maker implantation. Their ages at initial implantation ranged from 15 days to 16 years (Table). The cause of the rhythm disturbance was congenital in three and acquired in nine; of the latter, six were traumatic (operative). The basic rhythm was complete heart block in nine, intermittent block in two, and intermittent bradycardia-tachycardia with vari-
Accepted for publication March 27, 1975. From the Department of Surgery, St.
Louis University, School of Medicine. Read before the 32nd annual meeting of the Central Surgical Association, Chicago, Feb 27, 1975. Reprint requests to 1325 S Grand Ave, St. Louis, MO 63104 (Dr. Kaiser).
RESULTS
All patients have been followed up since implantation for an average of 4M years (range, nine months to 11 years). The one early death occurred in a 15-day-old boy on the second postoperative day from low cardiac output. There were two sudden late deaths, one in an 11-year-old boy five years after initial pacemaker insertion with heart block following repair of a right ventricular aneurysm and recurrent VSD, and the other in a 17y2-year-old boy lOVé years after initiation of pacing for postoperative heart block from repair of tetralogy of Fallot. In both instances, the boys had led very active lives and were verified as pac¬ ing well within a few days of death. In both instances, postmortem electrocardiograms showed electrically satis¬ factory pacemaker function and in one roentgenogram as¬ sured integrity of the leads. One was known to have fre¬ quent ventricular arrhythmias. Impulse generator failure was the most common indica¬ tion for reoperation. In these 12 patients, a total of 38 im-
Downloaded From: http://archsurg.jamanetwork.com/ by a Oakland University User on 06/10/2015
Clinical Data Patient
Date of
Age 5V2 yr
Implantation 7/6/64
6 yr
7/13/64
7yr
8/26/64
16 yr
5/6/66
No. of
Rhythm
Operative
Associated Disease Tetralogy of Fallot
Operative
Tetralogy of Fallot
Operative
Tetralogy of Fallot
& Heart Block
Permanent
Third-degree Permanent
Third-degree Permanent
Third-degree
Cause
Permanent
Third-degree
Congenital
9V2 yr*
7/29/70
Permanent
Operative
12V2yr
8/20/71
Permanent
17
4/25/72
Permanent
3yr
7/10/72
4 yr
8/1/72
mo
10 yr 6
mof
2
Variable Second- 8 third-degree
mo
10 yr 7
8yr 9
6/24/69
Third-degree
Third-degree
12
Time Paced 5 yr 1 mof
Idiopathic
days
15
Operations
Operative
Endocardial cushion defect Tetralogy of Fallot
mo
dayst
4 yr 7
mo
3 yr 6
mo
Congenital
2 yr 10
Permanent
Viral"
2 yr 7 mo
Third-degree Bradycardia-tachycardia
Operative
Third-degree
Transposition great vessels, atrial and ventricular septal
2 yr 6
mo
mo
defects
yr*
6/19/73
4V2 yr*
5/24/74
16
*
Variable First- & second-degree Permanent
Third-degree
Idiopathic
1 yr 8 mo
Congenital
9 mo
Girls.
t Deaths.
pulse generators were inserted, 30 asynchronous, six atrial synchronous, and two demand. The median time of gener¬ ator failure was 29.5 months for asynchronous pacemakers and 22.5 months for atrial synchronous pacemakers. Atrial synchronous or demand pacemakers were used in those patients with variable block. In no patient is atrial syn¬ chronous pacing currently in effect as atrial synchrony has failed in all, presumably due to decreased atrial voltage. Electrode fracture, the second most common indication for reoperation, occurred on 11 occasions in four patients. It occurred four times in one patient, three times in an¬ other, and on two occasions in each of the two other pa¬ tients. It has not been shown as a cause of sudden death in any of our patients and we have not attempted to limit
activity.
Stimulation threshold increase or exit block occurred on four occasions in two patients. In both, the myocardial electrodes had been inserted into the right ventricle in which a ventriculotomy had been done for repair for VSD. Both hearts were subsequently well captured by perma¬ nent transvenous electrodes at low thresholds. One of these later had conversion to left ventricular epicardial electrodes when the impulse generator was replaced for rate change. Positioning of this patient could precipitate intermittent cardiac capture. It was noted by roentgen¬ ogram that the electrode had withdrawn slightly from the
heart, secondary
to
growth.
Wound erosion occurred on three occasions and infec¬ tion in one patient required reoperation. Erosion was treated by revision of the impulse generator pocket or, as
with the two infected tion.
pockets, placement in
another loca¬
COMMENT
Impulse generator failure is the most frequent indica¬ pacemaker reoperation. This is principally due to battery exhaustion and secondarily to electronic failure.7' Our experience confirms that power source failure in chil¬ dren, as in adults, is the most frequent reason for reopera¬ tions.1 Impulse generator failure carries with it the theo¬ retical implication of sudden death, but most failures occur gradually and are easily detected and corrected by appropriate monitoring of patients. Reoperation carries with it the practical potential for infection each time the pacemaker system is manipulated. Any technique to re¬ duce the number of reoperations should reduce this haz¬ ard. Improved energy sources with greater longevity tion for
strive toward this end.68 Other methods to conserve energy have involved decreasing pacemaker output or pulse duration. Telephone surveillance systems have ex¬ tended the time conventional power sources can safely and effectively be left in place.5-9 While many of the el¬ derly will not need improved power sources because their longevity is influenced by complications of other diseases, children should potentially benefit from these improve¬ ments.
Electrode fracture, the second most common indication for reoperation in our children, is observed infrequently in adult patients.12 The fact that electrode fracture occurred only in the boys suggests that increased physical activity
Downloaded From: http://archsurg.jamanetwork.com/ by a Oakland University User on 06/10/2015
is related. These children engaged in normal, vigorous ac¬ tivities limited only be exclusion from organized, competi¬ tive or contact sports. Retroperitoneal pacemaker and electrode placement or having the leads exit through the diaphragm, to avoid angulation over the ribs or costal margin, might be helpful in reducing lead fractures. The relatively large pacemaker size has stimulated ef¬ forts in chosing the best location for impulse generator placement in the smaller child.310 In two instances, we have resorted to retroperitoneal impulse generator place¬ ment behind the left iliac crest in attempts to avoid skin erosion and injury to the electrode. The use of atrial synchronous pacemakers in children has been advocated by some as the ideal pacing mode.2 Our experience is at variance with this. In no instance is any patient currently being paced with atrial synchrony. All survivors have been converted to fixed-rate pacing for lack of atrial synchrony. While the theoretical advantages of atrial synchronous pacing have been extensively dis¬ cussed, for practical purposes asynchronous pacing in chil¬ dren has been associated with normal growth and develop¬ ment and has not impaired physical activity. Late sudden death occurred in two boys with complete heart block following repair of tetralogy of Fallot, five
and 10% years after institution of pacing. Pacemaker function was satisfactory in both by postmortem ECGs. The one child had been noted to have episodes of ventricu¬ lar irritability including ventricular tachycardia requiring defibrillation beginning nine years after pacing. It is notable that late sudden deaths, attributable to arrhyth¬ mias, in otherwise healthy patients following successful repair of tetralogy of Fallot have become more widely rec¬ ognized.11·12 In view of the similarity of the deaths and the clinical courses of these two patients, it is highly proba¬ ble that sudden ventricular arrhythmias were the cause of death in both instances. CONCLUSION From this experience it is apparent that asynchronous cardiac pacing has been effective in permitting unre¬ stricted activity along with normal growth and develop¬ ment in a group of children. The paced child requires vigorous surveillance for generator function and lead con¬ tinuity, but with close attention and repeated adjust¬ ments of the hardware, long-term survival with normal growth and development is attainable. Improved gener¬ ator reliability and longevity should strikingly improve the course of this group of patients.
References 1. Kaiser GC, Barner HB, Willman VL, et al: Surgical treatment of bradycardia. Arch Surg 98:612-618, 1969. 2. Stoney WS, William CA, Burrus GR, et al: Complications of long-term pacing. Read before the 21st annual meeting of the Southern Thoracic Surgical Association, Williamsburg, Va, 1974. 3. Lindesmith GG, Stiles QR, Meyer BW, et al: Experience with an implantable synchronous pacemaker in children. Ann Thorac Surg 6:358-364,
1968. 4. Daicoff GR, Aslami A, Tobias JA, et al: Management of postoperative complete heart block in infants and children. Chest 66:639-641, 1974. 5. Furman S: Transtelephone pacemaker monitoring: Five years later. Read before the 11th annual meeting of the Society of Thoracic Surgeons, Montreal, 1975. 6. Huffman FN, Norman JC: Nuclear-fueled cardiac pacemakers. Chest 65:667-672, 1974.
7. Lillehei RC, Romero LH, Beckman CB, et al: A new solid-state, long\x=req-\ life, lithium-powered pulse generator. Ann Thorac Surg 18:479-489, 1974. 8. Lewis KB, Criley JM, Nelson RJ, et al: Early clinical experience with the rechargeable cardiac pacemaker. Ann Thorac Surg 18:490-493, 1974. 9. Goldman BS, Heller JG, Noble EJ, et al: Critical analysis of pulse generator replacement. Ann Thorac Surg 18:156-163, 1974. 10. Williams GD, Campbell GS: Pacemaker installation in the pediatric patient: An improved technique. Surgery 66:412-414, 1969. 11. James FW, Kaplan S: Sudden unexpected cardiac arrest in patients after surgical correction for tetralogy of Fallot. Am J Cardiol 35:146,1975. 12. Quattlebaum TG, Varghese PJ, Neill CA, et al: Sudden death among postoperative patients with tetralogy of Fallot: A follow-up study of 251 patients for an average of 12 years. Am J Cardiol 35:164, 1975. 13. Bairan AC, Cherry JD, Fagan LF, et al: Complete heart block and respiratory syncytial virus. Am J Dis Child 127:264-265, 1974.
Discussion James W. Kilman, MD, Columbus, Ohio: I would like to con¬ group on bringing to our attention a problem that those of us who work in pediatrie cardiovascular surgery realize exists and yet one we do not think about too often. I was asked to discuss this paper and, as a result, looked up our own series of pacemakers in children; interestingly enough, we have had 12 children requiring pacemakers at the Columbus Chil¬ dren's Hospital of Ohio State University. Our problems have been quite similar to those the group pre¬ sented here. We do not have as good a follow-up, and maybe it in¬ dicates that the children in Columbus are a little more active than those in St. Louis, but we have had more wire fractures, and we have had five patients die. More and more is being learned about the postoperative results of the tetralogy of Fallot and from real¬ izing that these children do die from ventricular arrhythmias that occur after repair of the VSD in tetralogy. Some good studies in Cincinnati, by Dr. Kaplan and his group, have shown that if one does very careful studies the Fallot pa¬ tients have a very high incidence of ventricular arrhythmias. So, I think these deaths are probably a combination of failure of the
gratulate the
pacemaker systems and the natural history of the disease. Our recent indications show that we have not been required to put a pacemaker in for an acquired surgical block since 1969, but recently we have implanted one for Ebstein anomaly following to¬ tal repair and one in an attempt to improve a block acquired from viral myocardiopathy and for congenital block. I have two questions I would like to ask the authors: What in¬ formation do they have concerning sensing problems in the longterm use of pacemakers? We are running into this more and more often in our adult population with long-term use of pacemakers, particularly in the postoperative patient who has fibrosis, both endocardial and epicardial. Johann L. Ehrenhaft, MD, Iowa City: I enjoyed Dr. Marco's paper very much. This is a most difficult problem. The children who have rhythm disturbances and heart block at birth are a really troublesome group of patients. Most get along for a while, but some will have some heart failure early. We pres¬ ently have no pacemakers and leads that could be adequately min¬ iaturized for use in infants. The reports of placements of pace¬ makers in infants have been very sporadic.
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In the group of children who have atrioventricular dissociations
following cardiac operations, the incidence is now very low, the placement of pacemakers is often very necessary because they do not survive prolonged periods of atrioventricular block without Stokes-Adams attacks and other problems. The real dilemma is which patients to treat with pacemaker im¬ plants; very rigid criteria should be adopted before this group of patients is condemned to the lifelong problems of being pace¬ maker-dependent. I wish the authors would say more about the make of pacemak¬ ers, the mode of implantation, and the systems used, either stan¬ dard, lithium, or atomic. Our experience in about the same number of patients has been very difficult due to the frequence of change of the battery packs, frequent problems with electrode repair, and breakage and wound problems. Second, what exact system would they prefer and advise the young surgeon to put in today if he is faced with a block after the repair of a VSD or tetralogy of Fallot? Dr. Kaiser: Dr. Kilman, we have not had too much of a sensing problem with demand units in children. We have had problems with atrial pacing, and we believe this adds very little long-term, as it ceases to function after a period of time. We used atrial syn¬ chronous pacing infrequently. We have seen two instances of so-
called entrance block in adults who have failed to sense, and sup¬ press, a demand unit, both with epicardial electrodes. Dr. Ehrenhaft, no patient with congenital heart block has re¬ ceived a pacemaker unless he has become symptomatic. With con¬ genital heart block we consider symptoms necessary before in¬ serting a pacemaker. The reason most patients with permanent block following operation are not symptomatic is that with per¬ sistent postoperative block, we do not wait for symptoms to occur before inserting a permanent pacemaker. It has been well shown that epicardial electrodes are better. They maintain a lower threshold for a longer period of time. Cer¬ tainly the required operation, a thoracotomy, is well tolerated in children. This would be our preference for the lead system. We have had experience with pacemakers of three or four manufac¬ turers and usually employ asynchronous and, more rarely, demand
pacemakers.
There are techniques currently available to increase the life of the standard power source, such as reducing the pulse width, or the output of the pacemaker. We have had no experience with lith¬ ium batteries, but plan to insert atomic units, particularly in this group of patients who have potential for such long lives. This is one aspect which should be most helpful in the future manage¬ ment of these patients.
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