Electrophysiologic consequences of the arterial switch repair of d-transposition of the great arteries

Late Atrio-ventricular Block After Arterial Switch for D-transposition of the Great Vessels With Intact Interventricular Septum

Arterial switch operation for transposition of the great arteries without ventricular septal defect usually does not lead to atrio-ventricular conduction disturbances. We discuss the case of a young boy presenting with first and second degree supra hisian atrio-ventricular block late after switch operation.

Late Complications Following the Arterial Switch Operation

The arterial switch operation has been the principal treatment for transposition of the great arteries and its variants for the last 25 years. Early mortality has decreased significantly over time, but long-term complications include pulmonary artery stenosis, coronary artery obstruction, neoaortic valvar insufficiency, arrhythmia, and aortic arch obstruction. This article provides an overview of the history, anatomic patterns, surgical results, and possible operative solutions discussed in the literature for patients with transposition of the great arteries who undergo arterial switch operations that result in late complications. Published journal articles were identified through PubMed literature search. The authors selected 72 articles for analysis. It is concluded that modifications can be made to the arterial switch operation in an effort to meet the challenges presented by late complications.

Guidelines for the outpatient management of complex congenital heart disease

An increasingly complex group of children is now being followed as outpatients after surgery for congenital heart disease. A variety of complications and physiologic perturbations, both expected and unexpected, may present during follow-up, and should be anticipated by the practitioner and discussed with the patient and family. The purpose of this position article is to provide a framework for outpatient follow-up of complex congenital heart disease, based on a review of current literature and the experience of the authors.

Prevalence of arrhythmias and their risk factors mid- and long-term after the arterial switch operation

Early results of the arterial switch operation (ASO) for transposition of the great arteries (TGA) are good, but there are few mid- and long-term data on postoperative arrhythmias, especially in Japan. In this study, clinical data on 624 1-year survivors who had an ASO between 1976 and 1995 were collected from six institutes in Japan up to October 2002. Sixty (9.6%) 1-year survivors had significant arrhythmias. Bradycardia occurred in 22 patients, including complete atrioventricular block (CAVB) in 12, sick sinus syndrome (SSS) in 6, and second-degree atrioventricular block in 4. Syncope developed in 2 with CAVB and 2 with SSS. Ten patients with bradycardia underwent permanent pacemaker implantation. Supraveutricular tachycardia (SVT) was seen in 25 patients, including paroxysmal supraventricular tachycardia in 16, atrial flutter in 7, and atrial fibrillation in 2. Six patients with SVT received antiarrhythmic medication. SVT was transient in 20 and persistent in 5. Ventricular arrhythmias occurred in 13 patients, including nonsustained ventricular tachycardia in 5, paroxysmal ventricular contractions with couplets in 5, ventricular flutter in 2, and sustained ventricular tachycardia in 1. Four patients with ventricular arrhythmias received antiarrhythmic medication. Of the study patients, 8 died 1 year or more after ASO. Death was directly related to arrhythmia in 1 patient and was due to nonsustained ventricular tachycardia with severe congestive heart failure. The presence of a ventricular septal defect (VSD) was a risk factor for postoperative arrhythmia. Patients with TGA and VSD had more arrhythmias than those with TGA and an intact ventricular septum (13.7 vs 8.7%, p < 0.05), and this was especially true for CAVB (3.9% vs 1.0%, p < 0.05). In 36 patients clearly documented time onset of postoperative arrhythmia arrhythmia developed in 18 (50%) after less than 1 year and in 15 (42%) after more than 5 years. In summary serious arrhythmias after ASO were uncommon, but postoperative arrhythmias, such as unpaced CAVB, SSS, and VT, were related to morbidity and mortality. VSD was a risk factor for postoperative arrhythmia, especially CAVB. Approximately half of the arrhythmias developed late. Lifelong monitoring with respect to arrhythmia is needed for patients after ASO.

The electrophysiology of atrioventricular nodal reentry tachycardia following the Mustard or Senning procedure and its radiofrequency ablation

We describe the electrophysiological studies undertaken in four patients with atrioventricular nodal reentry tachycardia in the setting of concordant atrioventricular and discordant ventriculo-arterial connections (transposition). Radiofrequency ablation was attempted in three, all with success. Clear evidence of dual antegrade pathways through the atrioventricular node was present in only one of the four, but other characteristics of discrete fast and slow pathways into the atrioventricular node were present in all. Atrioventricular nodal reentry tachycardia was inducible in all. In the three patients in whom ablation was attempted, the application of radiofrequency energy to the low medial regions of the systemic venous atrium (morphologically left) consistently caused junctional accelerated rhythm, but these lesions were not successful in eliminating the tachycardia. Successful radiofrequency ablation required a retrograde approach to the region of the slow pathway in the pulmonary venous atrium (morphologically right).

Intra-atrial reentry tachycardia in pediatric patients

Intra-atrial reentry tachycardia (IART), also known as atrial flutter, is a major problem in pediatric cardiology and adult congenital cardiology. Patients have significant morbidity and even mortality associated with this arrhythmia. The use of antiarrhythmic medications has been disappointing in this population. Ablation techniques are being developed which offer some advantages over the use of medication. These techniques include: sophisticated mapping using entrainment, electro-anatomic and non-contact methods for assessment of the anatomy and the reentrant circuit; radiofrequency ablation methods which allow for the creation of linear and transmural lesions; and new methods for assessment of the effects of ablation which focus on the documentation of the creation of a new line of block. These new techniques provide hope for more effective ablation procedures and the possibility of definitive cure of atrial flutter in many patients in this population.

Long-term results of arterial switch repair of transposition of the great vessels

The arterial switch operation has become the preferred surgical procedure for transposition of the great arteries worldwide. The low operative mortality at "low-risk" institutions has been well documented. The advantages of the arterial switch compared with atrial-level repairs include a lower incidence of arrhythmias and the likelihood of normal systemic ventricular function over the long term. However, the long-term sequelae of this operation must be continually evaluated, including the fate of the supravalvular pulmonary and aortic anastomoses, growth of the aortic root, competency of the neoaortic valve, patency of the coronary arteries, effects on the conduction system, and adequacy of ventricular function. These anatomic results, as well as the neurodevelopmental outcomes of these patients, are summarized in this review. Copyright 1998 by W.B. Saunders Company

Sustained bundle branch reentry in a patient with hypertrophic cardiomyopathy and nondilated left ventricle

Ventricular tachycardia is a well-known complication in patients with hypertrophic cardiomyopathy. We report the case of a patient with hypertrophic cardiomyopathy with easily inducible monomorphic ventricular tachycardia. Electrophysiology study demonstrated that bundle branch reentry was the mechanism of the tachycardia. The tachycardia was rendered non-inducible by radiofrequency ablation of the right bundle branch.

Arrhythmias and intracardiac conduction after the arterial switch operation

Intraatrial baffling procedures such as the Mustard or Senning repair of transposition of the great arteries have been associated with a high incidence of cardiac arrhythmias. These abnormalities are thought to arise from trauma to the sinus node and atrial muscle during the procedure. In the arterial switch operation, there is little intraatrial manipulation other than the repair of the atrial septal defect. In theory, rhythm disturbances after the arterial switch operation should be less prevalent. From January 1, 1983, to December 31, 1990, 390 patients (230 with intact ventricular septum and 160 with a coexisting ventricular septal defect) underwent an arterial switch operation. Electrocardiograms and 24-hour Holter monitor studies were obtained in the 364 survivors at hospital discharge and during follow-up. Limited intracardiac electrophysiologic studies were performed 6 to 12 months after the operation.

RESULTS

Atrioventricular node function was preserved in most patients; seven patients (2%) had first-degree, two (0.7%) second-degree, and five (1.7%) had complete atrioventricular block (all with coexisting ventricular septal defect). All five patients with complete heart block received a permanent pacemaker. In those patients not having a permanent pacemaker, sinus rhythm was present in 96% on the surface electrocardiogram and 99% during 24-hour Holter monitor studies (1 month to 8.5 years, mean 2.1 years after the operation). Intracardiac electrophysiologic studies (n = 158) demonstrated normal corrected sinus node recovery times and AH intervals in 97% of patients. Atrial ectopy was present in 152 of 172 (81%) patients, with the majority (64%) of patients having only occasional premature beats without repetitive forms. Ventricular ectopy was a frequent finding during 24-hour monitoring. At hospital discharge 70% had ventricular ectopy; these values fell to 57% (in patients with intact ventricular septum) and 30% (in patients with a coexisting ventricular septal defect) at follow-up. In the early postoperative period, there were 25 episodes of supraventricular tachycardia (14 of which required therapy), 6 episodes of junctional ectopic tachycardia, and 9 episodes of ventricular tachycardia. The incidence of supraventricular tachycardia had fallen to 5% at follow-up, with no atrial flutter or fibrillation noted. Three patients had ventricular tachycardia on follow-up Holter studies. In summary, our results confirm the theoretical advantages of anatomic correction over atrial level correction of transposition of the great arteries with respect to preservation of sinus node function and low incidence of clinically significant tachyarrhythmias.

Factors influencing early and late outcome of the arterial switch operation for transposition of the great arteries

Between January 1983 and January 1992, 470 patients underwent an arterial switch operation at our institution. An intact (or virtually intact) ventricular septum was present in 278 of 470 (59%); a ventricular septal defect was closed in the remaining 192. Survivals at 1 month and 1, 5, and 8 years among the 470 patients were 93%, 92%, 91%, and 91%, respectively. The hazard function for death (at any time) had a rapidly declining single phase that approached zero by one year after the operation. Risk factors for death included coronary artery patterns with a retropulmonary course of the left coronary artery (two types) and a pattern in which the right coronary artery and left anterior descending arose from the anterior sinus with a posterior course of the circumflex coronary. The only procedural risk factor identified was augmentation of the aortic arch; longer duration of circulatory arrest was also a risk factor for death. Earlier date of operation was a risk factor for death, but only in the case of the senior surgeon. Reinterventions were performed to relieve right ventricular and/or pulmonary artery stenoses alone in 28 patients. The hazard function for reintervention for pulmonary artery or valve stenosis revealed an early phase that peaked at 9 months after the operation and a constant phase for the duration of follow-up. Incremental risk factors for the early phase included multiple ventricular septal defects, the rapid two-stage arterial switch, and a coronary pattern with a single ostium supplying the right coronary and left anterior descending, with a retropulmonary course of the circumflex. The need for reintervention has decreased with time. The arterial switch operation can currently be performed early in life with a low mortality risk (< 5%) and a low incidence of reintervention (< 10%) for supravalvular pulmonary stenosis. The analyses indicate that both the mortality and reintervention risks are lower in patients with less complex anatomy.

Late death after arterial switch operation for transposition of the great arteries

Fifty-nine patients survived for more than 1 month after an arterial switch operation (ASO). Diagnoses in these patients included transposition of the great arteries in 27, transposition of the great arteries with ventricular septal defect in 28, and double-outlet right ventricle in four. There were six late deaths (10%) during the follow-up period, and all of them occurred suddenly and unexpectedly. Four of the six late deaths were in patients who had undergone ASO in the neonatal period. Late deaths occurred from 40 days to 10 months after the operation. Autopsies were performed in all six patients. The cause of these late deaths was acute myocardial infarction. Five patients died of subendocardial infarction resulting from stenosis of the left main coronary artery. On pathologic examination, a fibrocellular intimal thickening was noted at the proximal region of the right and left coronary arteries, which resulted in 80% stenosis on average.

Arrhythmias after surgery for complete transposition: Do they matter?

SummaryConcern about long-term complications after intraatrial repair of complete transposition has been used as an argument in favor of "anatomic" repair by the arterial switch operation. Late arrhythmias, including loss of sinus rhythm and the development of supraventricular tachycardias, particularly atrial flutter, are widely reported after intraatrial repair. Despite modifications of technique, the electrophysiologic substrate for arrhythmia results from the extensive atrial surgery required. Arrhythmias occur, even in the "modern surgical era" after both Mustard and Senning operations, are progressive, and appear to be inevitable. The circulation after an intraatrial repair is more vulnerable to the effects of excessive tachycardia, and this may place the patient at risk from sudden cardiac death. Current attempts at individual stratification of risk are disappointing using even aggressive electrophysiologic approaches, and a combined assessment involving hemodynamics is likely to be necessary. The electrophysiologic and arrhythmic consequences of the arterial switch operation have been less extensively researched but, as might be expected, are quite different from those seen after intraatrial repair. The atrial activation sequence is relatively undisturbed, and sinus nodal dysfunction and supraventricular arrhythmia are uncommon. Ventricular extrasystoles are the arrhythmia most consistently found during the short follow-up currently available. In the longer term, myocardial ischemia, hemodynamic disturbances and autonomic imbalance may predispose to late arrhythmia. Current evidence would suggest that the lack of clinically significant arrhythmia and the restoration of the left ventricle to the systemic circulation are significant advantages of the arterial switch operation over intraatrial repair procedures.

Electrophysiologic findings after Fontan repair of functional single ventricle

Cardiac arrhythmias are well recognized sequelae of the Fontan operation for complex congenital anomalies. In this study the electrophysiologic effects of the Fontan procedure were evaluated in 30 patients who underwent cardiac catheterization with electrophysiologic study 1.9 +/- 1.3 years (mean +/- SD) after modified Fontan repair for functional single ventricle. Abnormalities of sinus node or ectopic pacemaker automaticity were detected in 50% (15 patients) by determination of a prolonged corrected sinus node or pacemaker recovery time. Total sinoatrial conduction time was prolonged in 50% of the patients with normal sinus rhythm. Sinus node or ectopic atrial pacemaker function was entirely normal in only 43% of patients. The predominant atrial rhythm was normal sinus in 70% and ectopic atrial or junctional in 30%. Abnormalities of atrial effective and functional refractory periods were noted in 43% of patients and were most pronounced at faster paced cycle lengths. Atrial endocardial catheter mapping revealed intraatrial conduction delays between adjacent sites in 76% of the patients tested and in eight of nine patients with inducible intraatrial reentry. Programmed atrial stimulation induced nonsustained supraventricular arrhythmias in 10% of the 30 patients and sustained arrhythmias in 27%. Intraatrial reentry was the most common inducible arrhythmia and was present in seven of the eight patients with sustained and two of the three patients with nonsustained atrial arrhythmias. Atrioventricular conduction abnormalities were noted in 10% (three patients). No patient had inducible ventricular arrhythmias with programmed ventricular stimulation. The electrophysiologic findings after Fontan repair include abnormal sinus node function, prolonged atrial refractoriness, delayed intraatrial conduction and inducible atrial arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Results of the arterial switch operation in patients with transposition of the great arteries and abnormalities of the mitral valve or left ventricular outflow tract

Between January 1983 and October 1989, 290 patients underwent an arterial switch operation for transposition of the great arteries; 30 (10.3%) of the patients had abnormalities of the left ventricular outflow tract or mitral valve, or both. These abnormalities included isolated pulmonary valve stenosis (n = 9), septal (dynamic) subpulmonary stenosis (n = 5), anatomic (fixed) subpulmonary stenosis (n = 7), abnormal mitral chordae attachments (n = 2) or a combination of abnormalities (n = 7). There were two early deaths, one of which was due to previously unrecognized mitral stenosis and a subpulmonary (neo-aortic) membrane and one late death due to presumed coronary obstruction. Of the nine patients with pulmonary valve abnormalities due to either a bicommissural (n = 5) or a thickened tricommissural (n = 4) valve, only one underwent valvotomy. Peak systolic ejection gradients in these nine patients measured preoperatively ranged from 0 to 50 mm Hg. At follow-up study 5 to 30 months postoperatively, the neo-aortic valve gradient was less than or equal to 15 mm Hg in all patients; three patients had mild neo-aortic regurgitation. Preoperative gradients may overestimate the degree of obstruction because of the increased pulmonary blood flow present in transposition. No patient with "dynamic" subpulmonary obstruction before the arterial switch operation had a surgical procedure performed on the left ventricular outflow tract; none had evidence of subaortic obstruction after the arterial switch.(ABSTRACT TRUNCATED AT 250 WORDS)

An electrocardiographic midterm follow-up study after anatomic repair of transposition of the great arteries

Prospective studies of rhythm and conduction, before and after 1-stage anatomic repair of simple transposition of the great arteries, were performed on 24 survivors. Pre- and postsurgical serial standard electrocardiograms were obtained on each patient. Fourteen patients underwent perioperative 24-hour electrocardiograms; all had follow-up 24-hour electrocardiograms. Rare atrial or occasional ventricular premature complexes were detected in 3 (11%) patients before operation. After surgery, 1 patient developed right bundle branch block. Two patients developed a left bundle branch block. One patient had a QS pattern in V6, which disappeared on follow-up electrocardiogram. Transient second-degree atrioventricular block was detected in 1 patient. A normal P-R interval and P-wave axis were present in all but 1 patient. Mild sinus bradycardia or rare atrial or ventricular premature complexes were detected in 4 of twenty-nine 24-hour electrocardiograms performed in the first 2 years after surgery. At 3 years after repair, 5 patients had a normal 24-hour electrocardiogram and 1 had low-grade ectopy (rare atrial and ventricular premature complexes). At 4 years, all 4 patients studied had normal 24-hour electrocardiograms. During a mean follow-up of 3 years, we have yet to document any symptomatic arrhythmias.

Results of the arterial switch operation for transposition of the great arteries with ventricular septal defect. Surgical considerations and midterm follow-up data

Between January 1983 and December 1987, 62 patients underwent an arterial switch operation for transposition of the great arteries with ventricular septal defect or double outlet right or left ventricle. There were three hospital deaths (4.8%), and no deaths occurred in neonates (less than 1 month of age, n = 18). There were three late deaths, one due to coronary obstruction and two due to pulmonary vascular obstructive disease. One child has been lost to follow-up. We have prospectively evaluated the remaining 55 survivors by clinical evaluation, echocardiography, cardiac catheterization, ambulatory electrocardiographic monitoring, and limited electrophysiologic studies. The mean length of follow-up has been 27 +/- 16 months since surgery. One child has required reoperation for a residual ventricular septal defect; no child has undergone reoperation for supravalvar pulmonary or aortic stenosis. Aortic regurgitation was identified in 12 children (22%), which was mild in 11 and moderate in one. One child has asymptomatic occlusion of the left main coronary artery, one child has a tiny right coronary artery-to-pulmonary artery fistula, and one child has abnormal left ventricular wall motion according to follow-up angiography. No other abnormalities of systemic (left) ventricular function have been identified at late follow-up. In addition to the two late deaths due to pulmonary vascular obstructive disease, three children, all of whom were repaired at more than 6 months of age, have elevated pulmonary vascular resistance. Notable postoperative arrhythmias include complete heart block in four patients and nonsustained supraventricular or ventricular tachycardia early after surgery in eight patients (all resolved without medication at later follow-up). Only two patients have evidence of sinus node dysfunction and have not required treatment. The low hospital mortality and encouraging early follow-up data represent a significant improvement over atrial level repairs, supporting the arterial switch operation as the procedure of choice for children who have transposition of the great arteries with ventricular septal defect or double outlet ventricle. Because of the potential for the development of early pulmonary vascular obstructive disease in these patients, repair is recommended within the first 2 months of life.