Postoperative complete heart block in children

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.

Permanent complete heart block following surgical correction of congenital heart disease

BACKGROUND

The risk of complete heart block (CHB) from congenital heart repairs in Ghana is unknown. This information is important for referring physicians and in pre-operative counselling of patients and facilitates the process of obtaining informed consent for such repairs.

OBJECTIVES

This study was undertaken to determine the incidence of permanent post-operative CHB requiring pacemaker implantation; and the post-operative problems related to the pacemaker.

DESIGN

Retrospective study design.

SETTING

The National Cardiothoracic Centre (NCTC), Korle-Bu Teaching Hospital, Accra, Ghana.

METHOD

Review of all patients who had intra-cardiac repair of congenital heart disease known to predispose to post-operative complete heart block from January 1993 to December 2008 was carried out with computation of the frequency of complete heart block according to the intra-operative diagnoses.

RESULTS

Six out of 242 patients (2.5%) developed permanent post-operative CHB. All underwent closure of a large perimembranous ventricular septal defect (VSD) either as an isolated defect (2 of 151 or 1.3%) or in the setting of conotruncal anomalies (4 of 73 or 5.5%). The dominant parental concern relating to the implanted device was the financial implications of future multiple surgeries to replace a depleted pulse generator.

CONCLUSION

Permanent post-operative complete heart block occurred in 1.3% of patients undergoing VSD repair and 5.5% of those undergoing repair of conotruncal anomalies (Fallot's tetralogy). The dominant anatomic risk factor was a large perimembranous VSD as an isolated defect or as part of a conotruncal anomaly. Permanent pacemaker implantation in this setting is attended by a low morbidity.

Late recovery of surgically-induced atrioventricular block in patients with congenital heart disease

OBJECTIVES

To assess the incidence and establish possible predictors of late recovery of post-surgical heart block, treated with pacemaker implantation, in patients with congenital heart defects.

BACKGROUND

The American College of Cardiology/American Heart Association Task Force has recommended pacemaker implantation for advanced second or third degree atrioventricular block which persists for 7 to 14 days after surgery. The incidence of late recovery of post-surgical heart block following pacemaker implantation has not been reported.

METHODS

Records of 44 patients with post-surgical heart block who underwent pacemaker implantation at our institutions since 1976 were reviewed for demographic, anatomic, surgical and surface electrocardiographic data to assess the incidence of, and factors associated with, recovery of atrioventricular conduction on long-term follow-up.

RESULTS

32% (14) of patients recovered atrioventricular conduction at a median follow-up of 5.5 years while 68% (30) remained pacemaker dependent. The groups were similar in age and weight at surgery and period of follow-up p = 0.5). Types of defect and surgical repair were not significantly different (p > 0.1). There was a similar number of patients with second degree-type II block in both groups (p = 0.15). The groups did not differ in timing of pacemaker implantation (<10 days p = 0.14, >14 days p = 0.18).

CONCLUSIONS

Late recovery of atrioventricular conduction following pacemaker implantation for postsurgical heart block is common. However, clinical predictors, with reference to current recommendations, could not be identified. Prospective electrophysiologic evaluations may be warranted to establish guidelines for long term pacemaker dependency and criteria for pacing.

[Arrhythmias in patients with congenital heart disease and their impact on prognosis]

Patients with congenital heart disease have an increased chance to suffer from brady- as well as tachyarrhythmias. The impact of these on quality of life, morbidity and mortality is more often imperative as compared to heart-healthy individuals. The substrate for these may be either congenital or acquired. Improvements of the surgical management of these patients have led, on the one hand, to improved survival rates with prolonged life expectancy within the last 2 decades, which on the other hand provided the basis for a higher rate of acquired cardiac arrhythmias. Together, this not only challenges diagnostics and therapy but also the prognostic relevance of these arrhythmias. The therapeutic strategies and prognostic markers have until now mostly been based on retrospective studies limited by the low number of patients and inhomogeneous patient selection. Despite these limitations, an increased risk of sudden cardiac death has been substantiated for certain patient groups, e.g., those operated on by the Mustard- or Senning procedures in patients with transposition of the great arteries and patients operated on with correction of the tetralogy of Fallot. However, until now it has not been possible to identify reliable markers for establishing the risk on an individual basis within these patient cohorts. For achieving reliable data on the symptomatic and prognostic effects of present-day--as well as new-coming--therapeutic strategies, it is mandatory to perform prospectively based, randomized multicenter studies. Furthermore, the well-appreciated synergism of hemodynamically and primarily of arrhythmia-based effects on prognosis could potentially be divided into their relative weight to better guide appropriate, substrate-related therapy. In addition, this should help to get better estimates of the risk for sudden cardiac death in different, etiologically homogeneous, groups of patients with congenital heart disease.

Electrical instability in patients undergoing surgery for atrioventricular septal defect

Postoperative 24-hour Holter monitoring was performed in 106 patients with atrioventricular septal defect in order to identify the incidence of atrial and ventricular arrhythmias. Of the patients, 72 had separate atrioventricular orifices, including 13 with a small ventricular component to the defect, and 34 patients had a common atrioventricular orifice. Two groups of abnormal patients were found. First, patients with good electrical stability characterized by isolated atrial (9 patients) and ventricular (25 patients) extrasystoles falling in classes I and II of Lown. Second, patients with marked electrical instability characterized in one patient by repetitive atrial extrasystoles, in another by atrial flutter, in 2 by polymorphic ventricular extrasystole and in 8 by couplets or triplets. Electrical instability in individual patients was then compared, by means of logistic regression analysis, with operative, surgical and postoperative variables. There was no incidence of sudden death in our series. After surgical repair, ventricular arrhythmias were more frequent than atrial arrhythmias (33% vs. 10%) and were unrelated to the type of atrioventricular septal defect. Cardiac electrical instability after operation was significantly related to larger operative body size, higher postoperative end diastolic diameter of the right ventricle, larger size of the ventricular septal defect, coexistence of postoperative right bundle branch block and left anterior hemiblock. Conversely, the risk of arrhythmias was reduced by more recent operative data and by greater shortening fraction of the left ventricle.

Electrophysiologic cardiac function before and after surgery in children with atrioventricular canal

Thirty-two children with atrioventricular (AV) canal underwent electrophysiologic studies: 18 underwent preoperative studies at a median age of 3 years (range 6 months to 16 years); 14 underwent postoperative studies at a median age of 4 years (range 2 to 19); and 2 underwent both preoperative and postoperative matched studies. In the preoperative group the following abnormalities were observed: first-degree AV block in 5 patients (due to internodal conduction delay in 1, AV nodal conduction delay in 2 and normal intracardiac intervals in 2); internodal conduction delay but normal PR interval in 4; and disease of the sinus node in only 1. In the postoperative group the following abnormalities were observed: first-degree AV block in 9 (due to AV nodal conduction delay in 2, His-Purkinje system conduction delay in 1, upper normal intracardiac intervals in 3 and unidentified in 3); prolongation of the right ventricular apical activation time in 11 of 13 with right bundle branch block; abnormal sinus node function in 3; and abnormal AV nodal function in 4 (1 of whom had associated sinus node disease). Atrial and ventricular functions were normal in all preoperative and postoperative patients. Electrophysiologic dysfunction is rare in preoperative patients with AV canal; in postoperative patients electrophysiologic abnormalities occur in 38% and involve the sinus and AV nodes in 19 and 25%, respectively.

Arrhythmias after coronary bypass surgery

Ninety patients undergoing coronary bypass surgery were studied prospectively by bedside and subsequent ambulatory electrocardiographic monitoring to investigate the incidence, possible causes, and prevention of atrial fibrillation. Patients with good left ventricular function were divided randomly into a control group or groups treated with digoxin or propranolol. In the control group the incidence of atrial fibrillation was 27% and of significant ventricular extrasystoles 3%. Propranolol reduced the incidence of atrial fibrillation (14.8%), whereas digoxin had no effect and increased the incidence of ventricular extrasystoles. Age, sex, severity of symptoms, cardiomegaly, heart failure, previous myocardial infarction, and number of grafts did not affect the result. The operative myocardial ischaemic time was related to the occurrence of atrial fibrillation. There was also a significant relation between atrial fibrillation and bundle branch block. Atrial fibrillation is common after coronary artery grafting; it may be due to diffuse myocardial ischaemia or hypothermic injury. The incidence may be reduced by beta blockade.

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.

Electrophysiologic characteristics of sustained ventricular tachycardia occurring after repair of tetralogy of fallot

The electrophysiologic characteristics of sustained ventricular tachycardia occurring after total repair of tetralogy of Fallot are reported. Four patients, 8 to 31 years of age, who had spontaneous episodes of sustained ventricular tachycardia underwent electrophysiologic study to determine the mechanism and site of origin of the tachycardia. In each patient, the tachycardia could be reproducibly initiated and terminated by programmed electrical stimulation. In two patients, initiation and maintenance of the tachycardia depended on the development and perpetuation of continuous electrical activity in the right ventricular outflow tract. These observations suggested a reentrant mechanism. In each patient, catheter endocardial mapping demonstrated the site of origin to be the right ventricular outflow tract. In two patients intraoperative mapping showed the reentrant circuit originating at the site of healed right ventriculotomy site. We conclude that sustained ventricular tachycardia after repair of tetralogy of Fallot in our patients was caused by reentry at the site of the previous operation in the right ventricular outflow tract.

Intraoperative identification of the conduction system in repair of endocardial cushion defect

Electrophysiological identification intraoperatively of the His-Purkinje system eliminates the complication of complete heart block consequent upon repair of endocardial cushion defect (ECD). Ten patients, 6 with complete ECD and 4 with incomplete ECD, underwent repair of the defect. None of the patients developed heart block. Slight variations were noted in the location of the His bundle in 9 patients, and a major deviation was found in 1 patient with incomplete ECD. The data support the use of intraoperative recordings as a necessary acconpaniment to the operative repair of ECD.

Reversion to sinus rhythm 11 years after surgically induced heart block

A patient is presented in whom the heart reverted spontaneously to sinus rhythm 11 years after surgical closure of a ventricular septal defect complicated by complete heart block. It seems unlikely that regeneration of fibres in the bundle of His, if these had indeed been destroyed, could account for the restoration of sinus rhythm after so long an interval.

Unexpected cardiac arrest in patients after surgical correction of tetralogy of Fallot

Four of 220 patients without bifasicular block (complete right bundle branch block and left anterior hemiblock) or transient complete heart block immediately after surgery had an unexpected cardiac arrest one to 15 years after satisfactory surgical repair of tetralogy of Fallot. The postoperative electrocardiograms (ECG) revealed complete right bundle branch block in two patients and no intraventricle conduction abnormality in two patients. Each of the four patients had premature ventricular contractions on previous postoperative ECG. The cardiac arrest occurred during normal activity in three patients and mild exercise in one. Following the cardiac arrest, three patients died and one patient survived. Eighteen months before the cardiac arrest, the survivor had a stress test which revealed multifocal premature ventricular contractions with short bursts of ventricular tachycardia after exercise. This ventricular arrhythmia was suppressed with quinidine therapy. Although complete heart block cannot be excluded in these four patients, we reasoned that the cardiac arrests were probably preceded by ventricular tachyarrhythmia. Because of this experience, we believe that any patient who has had intraventricular surgery should be evaluated for ventricular arrhythmia. If frequent premature ventricular contractions or serious ventricular arrhythmias are documented, we seriously consider antiarrhythmic therapy in an attempt to prevent ventricular tachyarrhythmias and sudden death.

Bundle of His recordings in congenital heart disease

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Conduction disturbances after surgical closure of ventricular septal defect

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