Postoperative complete heart block in 64 children treated with and without cardiac pacing

Incidence, Risk Factors, and Outcome of Cardiac Arrhythmia Postcardiac Surgery in Children

Objective

To study the incidence of postoperative cardiac arrhythmias in children undergoing cardiac surgery and to evaluate the risk factors and outcome of these patients.

Materials and Methods

This retrospective observational study was conducted in the cardiac pediatric intensive care unit and included children <18 years of age. Children were monitored in the early postoperative period (72 h) for any sustained rhythm abnormality and were classified using standard definition. Details of treatment and their response were assessed. Risk factors for arrhythmias were evaluated using multivariate logistic regression analysis.

Results

Five hundred and thirty-six children were included and the prevalence of arrhythmia was 14.4% (n = 77). The most common arrhythmia was complete heart block (CHB) (n = 28; 5.2%), followed by junctional ectopic tachycardia (JET) (n = 25; 4.7%), junctional escape rhythm (n = 13; 2.4%), supraventricular tachycardia (SVT) (n = 8; 1.5%), and ventricular tachycardia (VT) (n = 3; 0.6%). Cardiac pacing was required in all CHB; 8 (28.6%) required a permanent pacemaker. Six (24%) patients with JET responded to conventional measures; 19 (76.0%) patients required amiodarone and 5 (20%) required cooling to 34°C or cardiac pacing. Temporary cardiac pacing was required in 9 (69.2%) cases of junctional escape rhythm. Seven (87.5%) events of SVT responded to adenosine and 1 (12.5%) required cardioversion. Two (66.7%) of VT responded to cardioversion while 1 (33.3%) was refractory. Five (6.5%) patients with arrhythmia died. In the multivariate logistic regression analysis, age <1 year, risk adjustment for congenital heart surgery category ≥3, and cross-clamp time >67 min were independent risk factors.

Conclusion

Early postoperative period following cardiac surgery is extremely vulnerable to cardiac arrhythmias. Although majority are self-limiting, some can be life-threatening.

Incidence and characteristics of heart block after heart surgery in pediatric patients: A multicenter study

BACKGROUND

Advanced second- or third-degree heart block has been reported with variable incidence after surgery for congenital heart disease in children. We report the incidence of heart block requiring a pacemaker and describe the risk factors for this complication in a large multicenter study.

METHODS

We performed a retrospective cohort study, using the Pediatric Health Information System database from 45 hospitals in the United States, for all children aged 18 years, discharged between January 1, 2004, and December 31, 2013, who underwent open surgery for congenital heart disease. Patients who had heart block and placement of a pacemaker during the same hospitalization were identified. Demographic characteristics, procedure and diagnostic codes, length of stay, and mortality were analyzed. Univariable and multivariable analyses were performed.

RESULTS

There were 101,006 surgeries performed. The median age of patients was 0.5 years (interquartile range, 26 days to 3.2 years), and 1% of patients (n = 990) had heart block and placement of a pacemaker. Surgeries associated with the highest incidences of heart block and placement of a pacemaker included the double switch operation (15.6%), tricuspid valve (7.8%) and mitral valve (7.4%) replacement, atrial switch with ventricular septal defect repair (6.4%), and Rastelli operation (4.8%). On multivariable analysis, after controlling for surgical complexity, other comorbidities, age at surgery, admission year, and clustering by institution, patients with heart block and placement of a pacemaker had higher odds of mortality (odds ratio, 1.67; 95% confidence interval, 1.24-2.26; P < .001).

CONCLUSIONS

The incidence of postoperative heart block requiring permanent pacemaker placement immediately after congenital heart surgery is low (1%). However, these patients have higher mortality even after adjusting for heart surgery complexity.

Natural history and current therapy for complete heart block in children and patients with congenital heart disease

Complete heart block, either congenital or acquired, in children and patients with congenital heart disease is a relatively frequent occurrence requiring therapy. The natural history of this condition has been distorted by the advent of new diagnostic and therapeutic modalities. The therapy of complete heart block is evolving with new data suggesting that traditional treatment strategies utilizing right ventricular apical pacing may have inadvertent deleterious effects on cardiac function. In the following manuscript, the natural history of complete heart block is reviewed and the current therapy examined.

Natural history of postoperative heart block in congenital heart disease: Implications for pacing intervention

After half a century of major progress in congenital heart disease management, atrioventricular conduction block continues to complicate 1-3% of surgical procedures. Unless treated with an implanted pacemaker, permanent postoperative heart block is associated with 28-100% mortality. Postoperative heart block often proves to be transient, typically resolving within 10 days of onset. The duration of postoperative heart block is widely used as a key determinant for permanent pacemaker implantation. Current professional pacemaker implantation guidelines are largely based on this criterion. However, available natural history data suggest that other factors, such as residual conduction system injury, likely play a role in increasingly recognized cases of very late postoperative mortality and morbidity in patients who have experienced transient postoperative heart block. As growing numbers of congenital heart disease patients survive into adulthood, and artificial pacemaking capabilities continue to improve, it might be necessary to reconsider and refine currently accepted pacing indications for postoperative heart block.

Management of postoperative arrhythmias and junctional ectopic tachycardia

The critical postoperative period in children who have undergone palliative or corrective surgery for congenital heart disease is often complicated with cardiac arrhythmias. In spite of improved myocardial preservation techniques and better understanding of the surgical anatomy of the conduction system, postoperative arrhythmias are inevitable. Although most arrhythmias are transient, they can be associated with high mortality and morbidity if vigorous appropriate management is not instituted. This is especially true for postoperative junctional ectopic tachycardia. Lack of atrioventricular synchrony and reduced diastolic time secondary to a fast heart rate lead to decreased cardiac output, and the patient's condition tends to deteriorate rather rapidly. Recent advances in the management of postoperative arrhythmias have been gratifying. The most encouraging response has been that of junctional ectopic tachycardia to intravenous amiodarone. Also, the practice of routinely placing temporary epicardial wires in all patients undergoing surgery for congenital heart disease has provided a very useful diagnostic and therapeutic tool. Early recognition, precise diagnosis, and timely therapy can be very effective in avoiding adverse hemodynamic consequences of postoperative arrhythmias. Copyright 1998 by W.B. Saunders Company

Heart block in children. Evaluation of subsidiary ventricular pacemaker recovery times and ECG tape recordings

To evaluate subsidiary ventricular pacemaker function in 20 children with congenital or surgically induced complete heart block, we measured recovery times following overdrive ventricular pacing. Long-term ECG tape recordings were performed in eight of these children. Ages ranged from 1 month to 17 years. The resting R-R intervals ranged from 595 to 1,740 msec. The ventricles were paced at various cycle lengths of 400 to 1,000 msec with either transvenous electrode catheters or surgically implanted epicardial electrodes. His bundle recordings showed that the site of block did not allow separation of patients with symptoms from those without symptoms. Prolonged recovery times were present in patients with block above the His bundle recording site who had symptoms of syncope or dizziness, as well as in patients who had a wide QRS. However, some asymptomatic patient with heart block above the His bundle recording site also had long recovery times. None of the asymptomatic patients who had ECG tape recordings had paroxysmal tachycardia in more than 300 hours of recordings. However, one symptomatic patient with congenital heart block and a prolonged recovery time had brief episodes of paroxysmal ventricular tachycardia that produced no symptoms at the time of recording. The results suggest that the coexistence of prolonged recovery times and paroxysmal tachycardia may be predisposing factors to the development of symptoms in patients with complete heart block. We believe that further electrophysiologic investigation of this possibility is warranted in patients with heart block.

Indications, effectiveness, and long-term dependency in permanent pacing after cardiac surgery

The purposes of this study were to define predictors of long-term pacemaker dependency in patients having permanent pacemakers implanted shortly after cardiac surgery, and to evaluate short- and long-term results and survival in this population. Data from 120 adult patients with implantation since 1980 were retrospectively analyzed. Acute and chronic complication rates (4.2% and 16.6%, respectively) were not higher than those expected in the general paced population. In addition, continuous rhythm was evaluated by use of pacemaker inhibition in a subgroup of 20 patients to verify the validity of clinical criteria for pacemaker dependency. Of the patients evaluated for dependency, 41% eventually became nondependent. Prolonged monitoring with an inhibited pacemaker confirmed the accuracy of our method of clinical evaluation of pacemaker dependency. Significant predictors of long-term pacemaker dependency were complete atrioventricular block as the indication and bypass time of > 120 minutes (by multivariate and univariate analyses, respectively). Postoperative complete atrioventricular block is the most important predictor of pacemaker dependency, enabling an earlier decision on permanent pacemaker implantation (no later than the sixth and the ninth postoperative days for wide-complex and narrow-complex escape, respectively). Further prospective studies are needed to define optimal implantation times for indications other than complete atrioventricular block.

Implantation of transvenous pacemakers in infants and small children

A series of 14 infants and small children ranging from 7 months to 7 years in age (mean, 2.5 years) underwent implantation of transvenous pacemaker systems. Three factors are of utmost importance in children: small subclavian vein size, thin subcutaneous layer in the chest, and growth. A five-point protocol is followed strictly: (1) duplex assessment of upper veins, (2) use of active fixation leads, (3) use of short (36 to 45 cm) leads, (4) anchoring of pulse generator with nonabsorbable material to prevent migration, and (5) routine use of the "lateral approach" in children more than 2 years old when the pulse generator is implanted in the chest. Because lead diameters measure 2 to 2.3 mm, a one-lead system needs a vein diameter of 5 mm (cross-sectional area of 19 mm2). A two-lead system needs a vein at least 7 mm in diameter and a cross-sectional area of 38 mm2 to prevent vein occlusion. Therefore all children less than 3 years of age had the leads implanted via the internal jugular vein. In 50% of children between 4 and 7 years of age, the internal jugular system also was used. Children more than 7 years old have leads implanted via the subclavian veins. Duplex ultrasound assessment of the upper veins is important to decide route of implantation. Use of short leads is recommended to reduce bulk at the pulse generator site. The "lateral approach" prevents problems at the generator implantation site.

Sudden death after repair of double-outlet right ventricle

The outlook for patients with double-outlet right ventricle has improved since the development of corrective operations. Late arrhythmic deaths after successful procedures have been reported; however, the magnitude remains unknown. This study was undertaken to identify the magnitude of late sudden death and the significant factors associated with it. From 1965 through 1985, 118 patients underwent corrective operation for double-outlet right ventricle; of these, 23 died in the hospital and six were lost to follow-up. The 89 remaining patients (52 male and 37 female) made up the study population. Their mean age (+/- SD) was 10.3 +/- 7.8 years at the time of repair. The mean duration of follow-up was 82 months. Of the 22 late deaths, 16 (73%) were sudden. Eight (50%) of the sudden deaths occurred within 1 year of operation. Cox proportional hazards multivariate analysis revealed the following significant risk factors for late sudden death: older age at the time of operation, perioperative or postoperative ventricular tachyarrhythmias, and third-degree atrioventricular block. Factors not associated with late sudden death included year of operation, sex, type and number of associated cardiac anomalies, preoperative functional class, previous palliative procedures, surgical technique, perioperative or postoperative single premature ventricular contractions, and postoperative left or right bundle branch block with or without fascicular block. We conclude that the incidence of late sudden death after successful surgical repair of double-outlet right ventricle is very high. Complete corrective operation at an early age and aggressive diagnosis and treatment of arrhythmias and conduction defects after operation are warranted.

Evaluation of pacemaker pulse generator and patient longevity in patients aged 1 day to 20 years

The longevity of pediatric patients requiring pacemakers and the survival rates of the implanted generators were evaluated. From January 1970 to December 1985, 96 patients aged 1 day to 20 years underwent 162 pulse generator implantation procedures. Indication for initial implantation was surgically induced heart block in 52 patients, sick sinus syndrome in 20, congenital complete heart block with symptoms of low cardiac output in 19 and tachydysrhythmia control in 5. Modal age at initial implantation was less than 1 year; median age was 5 years. During this period 90 generators were removed from service: 49 (54%) because of generator failure, 22 (24%) because the patient died, 12 (13%) because of elective upgrade at the time of lead failure or cardiac surgery, 5 (6%) because of generator pocket infection and 2 (2%) because of manufacturer's recall. Pulse generators were separated into 4 groups based upon generator technology. Group I (n = 16) were asynchronous units with mercury-zinc batteries; group II (n = 18) were single-chamber demand units with mercury-zinc batteries; group III (n = 14) were single-chamber demand units with rechargeable batteries; and group IV (n = 114) were single- or dual-chamber demand units with lithium batteries. Patient survival rate was 84% at 6 months and 70% by 109 months. There was no further decrease to the end of the study period. Six-month generator survival rate was 82% for all groups, mostly a reflection of patient deaths.(ABSTRACT TRUNCATED AT 250 WORDS)

Pacing in children

Fourteen children had a permanent pacemaker implanted between May 1967 and July 1983. Postoperative complete heart block was the indication in nine cases, congenital complete heart block in three, and sick sinus syndrome in two. Two patients died, one suddenly and one after aortic valve replacement. A total of 48 pulse generators were implanted; five patients were given an isotopic pacemaker. Twelve patients had epicardial leads implanted initially, and two received a transvenous endocardial system. The lead system implanted initially remained without malfunction in only seven patients. In the other seven patients 20 lead malfunctions occurred. Psychological maturity and physical development seemed to be normal in all 14 children. Improvement in equipment and technique will improve the outlook for paced children in the future.

Redundant pacing: case report and review

A 17-year-old boy with severe sick sinus bradycardia had a doubly redundant pacemaker inserted. With two separate ventricular leads inserted by the epicardial route, the pacemaker is able to compensate for a lead that has developed high threshold by activation of an alternate lead. The two pacing channels of the pulse generator can be programmed independently of one another. In addition, there is a back-up pacing circuit separate from the two primary channels. The pacer can be used with both channels active for continuous automatic redundancy for safety, or with one channel active and the other in reserve.

Transient atrioventricular block after open-heart surgery for congenital heart disease

The records of 22 patients with transient atrioventricular (AV) block after open-heart surgery for congenital heart disease from 1972 to 1978 were reviewed to determine the natural history of this entity. Preoperatively, no patient had AV block; 3 had right bundle branch block (BBB), 1 had left BBB and 5 had nonspecific intraventricular conduction delay. Complete AV block developed in 20 patients and Mobitz II AV block in 2. Transient AV block occurred intraoperatively in 14 patients and within 48 hours postoperatively in 8; AV block persisted for greater than or equal to 48 hours postoperatively in all patients, for a mean of 7.3 days (range 2 to 28). During a follow-up of 5.5 years (range 2.5 to 10), late AV block developed in 2 patients. None of the 18 patients whose escape QRS complex morphology during AV block was similar to the final QRS complex during normal sinus rhythm or atrial fibrillation with AV conduction had late AV block, whereas 2 of the 4 in whom it differed did (p less than 0.01). There was no difference in the escape rate between the 2 groups. Thus, late development of high-grade AV block is infrequent among patients with transient postoperative AV block. An escape QRS complex during postoperative AV block that differs from the QRS complex seen on recovery of normal sinus rhythm or atrial fibrillation with anterograde conduction may identify those at high risk of late AV block.

Ventricular pacing in children

Ventricular pacing was performed in forty-one children ranging from one day to twenty years of age (median age = 10). Weight of the recipient at implant ranged from 2 kg. to 86 kg. Indications included presyncope, syncope, dyspnea on exertion, congestive heart failure, postoperative infra-Hisian heart block, and inadequate cardiac rate during pharmacotherapy. Four patients died during follow-up, but no deaths were attributable to pacemaker management. In contrast, 66% of the patients required more than one pacemaker related-operative procedure, and 43% of leads implanted failed by 48 hours. Indications for permanent cardiac pacing in this population at this time are symptomatic congenital AV block, symptomatic sinus node disease, and AV block in the postoperative period. Technological developments which might reduce complications seen in this population and electrophysiologic techniques which may better define indications for pacing in children are also reviewed.

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.

Cardiac pacing in children

Twenty patients aged between 12 months and 13 years underwent permanent pacemaker implantation. The main indication for pacing was post-surgical atrioventricular block. The complication rate was high and related mainly to infections and lead system problems. The use of small multiprogrammable pacemakers is expected to reduce the reoperation rate for system malfunction and elective replacement. Newer methods of electrode insertion and active fixation devices in smaller diameter leads make endocardial pacing a practical alternative to epicardial pacing in the larger child who did not require a pacing system at the time of surgery.

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.

Comparison of the sutureless and suture-type epicardial electrodes in pediatric cardiac pacing

Fourteen consecutive patients with the suture-type electrode (Group 1) were compared with the previous 14 patents having the sutureless electrode (Group 2). five patients in Group 1 had had failure with the sutureless electrode, for a total of 23 patients. In Group 1, no exit block was encountered. One patient had sensing problems corrected simply by increasing the pacer rate. One patient had generator failure and another, lead fracture. In 5 patients in Group 2, exit block developed early (less than 6 months after implantation); 3 patients had the problem twice, making a total of eight early failures. Two patients had late exit block (more than 6 months after implantation). Improved results with the suture-type electrode can probably be explained by its smaller head, larger surface area, ease of placement in a small space, and control of direction and depth of implantation.

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.

Temporary pacemaker treatment in open heart surgery: pre- to postoperative changes in the electrogram characteristics

Thirty-three patients undergoing cardiac surgery in general hypothermia were investigated during temporary pacemaker treatment for changes in right ventricular electrogram amplitudes (AMAX, UMAX) and maximum derivatives (DMAX, SMAX) from pre-to postoperative phase (AMAX = amplitude of the part of the electrogram with highest mean maximum derivative (SMAX), DMAX = maximum derivative, UMAX = maximum amplitude deflection). Standard commercially available electrodes were used in 28 of the patients. A paired comparison (n = 29) showed a fall in AMAX from 8.64 +/- 0.91 mV (mean +/- SEM) preoperatively to 4.94 +/- 0.43 mV (p < 0.001) between the 4th and 6th postoperative day; UMAX dropped from 11.09 +/- 0.95 mV preoperatively to 5.44 +/- 0.42 mV (p < 0.000001) from the fourth to the sixth postoperative day. In the same period DMAX fell from 1.57 +/- 0.13 V/s to 0.67 +/- 0.05 V/s (p < 0.000001), and SMAX from 0.76 +/- 0.06 V/s to 0.32 +/- 0.02 V/s (p < 0.000001). The most marked fall in amplitudes and maximum derivatives occurred during the first 24 hours. A slight, but nonsignificant increase occurred in amplitudes and maximum derivatives from the 4th to 6th postoperative day until the electrodes were removed the 10th to 19th postoperative day. Amplitudes and maximum derivatives were of the same value in patients with aortic valve compared with coronary heart diseases in spite of a more deteriorated myocardial function in the former group. The changes in amplitudes and maximum derivatives followed the same pattern in the two groups from the pre- to postoperative phase. This indicates that the additional local hyperthermia applied to the patients undergoing valve surgery was of no importance in the electrogram changes. Despite the fact that the electrogram maximum derivative and maximum amplitude needed to inhibit a temporary pulse generator are of a low magnitude, the values found were so small that they might provoke demand failure. This actually occurred in four patients.

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.

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.