Corrected transposition with severe intracardiac deformities with Wolff-Parkinson-White syndrome in a child. Electrophysiologic investigation and surgical correction

Management Options for Congenitally Corrected Transposition: Which, When, and for Whom?

Management strategies for congenitally corrected transposition of the great arteries (ccTGA) historically consisted of a physiologic repair, resulting in the morphologic right ventricle (mRV) supporting systemic circulation. This strategy persisted despite the development of heart failure by middle age because of the reasonable short-term outcomes, and the natural history of some patients with favorable anatomy (felt to demonstrate the mRV's ability to function in the long-term), and due to the less-than-optimal outcomes associated with anatomical repair. As outcomes with anatomical repair improved, and the long-term risk of systemic mRV dysfunction became apparent, more have begun to realize its advantages. In addition to the decision on whether or not to pursue anatomical repair, and the optimal timing, studies demonstrating the nuance to morphologic left ventricle retraining have demonstrated its feasibility. Further considerations in ccTGA have begun to be better understood, including: the management of a poorly functioning mRV, systemic tricuspid valve regurgitation, the utility of morphologic left ventricle outflow tract obstruction (native or surgically created) and pacing strategies. While some considerations are apparent: biventricular pacing is superior to univentricular, tricuspid regurgitation must be managed early with either progression towards anatomical repair (pulmonary artery banding if needed for retraining) or tricuspid replacement (not repair) based on the patient's age; others remain to be completely elucidated. Overall, the heterogeneity of ccTGA, as well as the unique presentation with each patient regarding ventricular and valvular function and center-to-center variability in management strategies has made the interpretation of published data difficult. That said, more recent long-term outcomes favor anatomical repair in most situations.

Multiple accessory pathways in the young: the impact of structural heart disease

BACKGROUND

The presence of multiple accessory pathways (MultAP) is described in structural heart disease (SHD) such as Ebstein's anomaly and cardiomyopathies. Structural defects can impact the tolerability of tachyarrhythmia and can complicate both medical management and ablation. In a large cohort of pediatric patients with and without SHD undergoing invasive electrophysiology study, we examined the prevalence of MultAP and the effect of both MultAP and SHD on ablation outcomes.

METHODS

Accessory pathway number and location, presence of SHD, ablation success, and recurrence were analyzed in consecutive patients from our center over a 16-year period.

RESULTS

In 1088 patients, 1228 pathways (36% retrograde only) were mapped to the right side (TV) in 18%, septum (S) in 39%, and left side (MV) in 43%. MultAP were present in 111 pts (10%), involving 250 distinct pathways. SHD tripled the risk of MultAP (26% SHD vs 8% no SHD, P < .001). Multivariable adjusted risk factors for MultAP included Ebstein's (OR 8.7[4.4-17.5], P < .001) and cardiomyopathy (OR 13.3[5.1-34.5], P < .001). Of 1306 ablation attempts, 94% were acutely successful with an 8% recurrence rate. Ablation success was affected by SHD (85% vs 95% for no SHD, P < .01) but not by MultAP (91% vs 94% for single, P = .24). Recurrence rate was higher for SHD (17% SHD vs 8% no SHD, P < .05) and MultAP (19% MultAP vs 8% single, P < .001).

CONCLUSIONS

MultAP are found in 10% of pediatric patients, and are more common in SHD compared to those with normal hearts. Both the presence of MultAP and SHD negatively influence ablation outcomes.

Outcomes of radiofrequency catheter ablation of atrioventricular reciprocating tachycardia in patients with congenital heart disease

OBJECTIVES

Assessment of clinical outcomes of catheter ablation of atrioventricular reciprocating tachycardias in patients with congenital heart disease (CHD).

BACKGROUND

Atrioventricular reciprocating tachycardias occur in patients with CHD and may be poorly tolerated.

METHODS

Retrospective review of all 105 such ablations in 83 patients performed between 03/90 and 02/02 at one institution.

RESULTS

The dominant arrhythmia mechanism was accessory pathway (70 patients, 84%), and the most common indications were drug-refractory tachycardia, life-threatening arrhythmia, and elective presurgical ablation. Congenital heart disease diagnoses were diverse, with one third of patients having Ebstein's anomaly. Twenty patients (24%) had catheter access limited by prior surgeries or occluded vascular access. Of 109 accessory pathways (APs), 74 (68%) were manifestly preexcited, and 71 (65%) were located on the right atrioventricular groove. Fourteen patients (20%) had multiple pathways. There were 2 major complications (1 death, 1 hemorrhage), and 3 minor complications (5.5% of procedures). Acute success rate was 80% per procedure, 82% for left- and 70% for right-sided APs. Acute success rates for patients with Ebstein's anomaly were similar to patients with other CHD diagnoses, but Ebstein's patients were more likely to have recurrence. At 44 +/- 35 months follow-up, successful ablation was achieved in 59% of procedures and 68% of patients, with 19 patients (23%) undergoing one or more repeat ablations.

CONCLUSIONS

Compared to patients with normal cardiac anatomy, patients with CHD of all varieties have lower rates of acute and long-term success for ablation for atrioventricular reciprocating tachycardias.

Role of catheter and surgical ablation in congenital heart disease

The role of surgery and radiofrequency current ablation for the treatment of tachycardias in patients with congenital heart disease The use of radiofrequency current application as a treatment strategy has stimulated a revolution in our understanding of tachycardia mechanisms. The extension of its use to patients with congenital heart defects and tachyarrhythmias has opened the door to new treatments with known success rates and known risks for mortality and morbidity. Antiarrhythmic surgery aims to dissect or excavate a responsible substrate and is especially worth considering if cardiac surgery is being undertaken for other reasons. With suitable surgical skill and interest, and with strong electrophysiologic support, high success rates have been documented. Antiarrhythmic surgical incisions have the advantage of being visually controllable regarding the extent and location of damage to myocardial tissue. In other situations, radiofrequency current ablation is preferred because of its less-invasive character, its use of local anesthesia, and the avoidance of surgical trauma. Both surgery and catheter ablation require precise clarification of the tachycardia mechanism and precise localization of the underlying substrate. The importation of such techniques into the realm of open chest surgery would be difficult in light of the need for multiple intracardiac catheters and repeated fluoroscopically guided catheter positioning. Electrophysiologic studies performed during the antiarrhythmic surgical procedure cannot provide complete information, and their use is thus restricted to the arrhythmogenic myocardial target only [32,45]. In contrast, catheter-mediated electrophysiologic studies offer the option of exact diagnosis, precise substrate localization, and interventional treatment in a single session. Moreover, validation of the linear lesion's completeness has become a reliable predictor for mid- and long-term success in avoiding recurrences. As a result, the application of catheter-mediated ablation has exploded within the past 15 years. Antiarrhythmic surgery has survived as a discipline in a decreasing number of experienced hands [43,44]. As a result of recent experiences and modern technology, success rates above 90% [74-76, 81,88] for the interventional treatment of congenital tachycardias have become comparable to those reported in patients with "normal" hearts. For acquired tachycardias, acute success rates today range about 80% at the atrial level. The rate of recurrence is still relatively high at about 10-25% [73,76,77,79,91,96,102]. Further improvements are being pursued. Data on the treatment of acquired tachycardias at the ventricular level is largely anecdotal. Good early success rates are combined with a tendency to recurrence in longer-term follow-up [50,76,103-108]. Some of the late VT ablation recurrences may be explained by the fact that fibrotic, scarred, and hypertrophic myocardial tissue at the targeted site often prevents effective radiofrequency current application and lesion generation. In order to improve RF lesion depth and continuity, newly designed technologies for radiofrequency current ("cooled tip electrode", Cordis Webster, Baldwin Park, CA), and alternative energy sources (cryo-ablation, micro-wave, or ultrasound) are being readied for introduction in the very near future. For patients suffering from recurrent tachycardias and having other reasons for open-heart surgery, a hybrid concept can be created, utilizing modern 3-D electro-anatomical reconstruction as a basis for an electrophysiologically informed surgical procedure. Following such a concept, a hemodynamic catheterization can be combined with an electrophysiologic study to define critical myocardial zones for induced macro-re-entry tachycardias, or of those zones expected to play an arrhythmogenic role in the future. With such information, surgical incisions for cardiac access and repair can be planned and performed. The role of surgery in antiarrhythmic treatment can become preventive. Myocardial tissue is incised for cannulation and repair in a way that can reduce the chance of later scar-associated tachycardias [109]. The extension of surgical cuts to physiologic barriers of electrical conduction is a major strategy for the primary prevention of postsurgical or incisional arrhythmias. In addition, the simultaneous treatment at heart surgery of already existing tachycardias can be offered within the same session as a secondary preventive concept. Despite the immense growth of knowledge and experience in recent years, there is still a need for more knowledge about the factors causing arrhythmogenesis and their interactions. Prospective and randomized studies are needed to show the most effective strategies to prevent arrhythmia-mediated death. The future of antiarrhythmic treatment will less be directed by the limitations of current interventional tools, which will be improved, and more by an evolutionary process in philosophy regarding the understanding of arrhythmogenesis in these patients as the basis for new concepts of arrhythmia prevention and treatment.

[High frequency current ablation of supraventricular tachyarrhythmias in congenital heart defects]

Supraventricular tachycardia is a frequent cause of disease in patients with congenital heart defects and has a potentially high impact on quality of life, morbidity and mortality of this patient cohort. Conventional treatment often fails to avoid recurrences of tachycardia in a long-term perspective. Potential side effects of antiarrhythmic drugs include aggravation of heart disease related disturbances of impulse generation and conduction properties or negative inotropic effects on haemodynamically impaired ventricular chambers. For these reasons, interventional electrophysiology is increasingly used for the treatment of supraventricular tachycardias in patients with congenital heart disease. Until March 1998 a total of 83 patients with congenital heart defects underwent an attempt for radiofrequency current treatment of supraventricular tachycardias. Among these were 36 children with an age of 5 months to 15 years (8.2 +/- 4.6 years) and 4.7 grown ups with an age of 17 to 76 years (39.3 +/- 14.3 years). In a natural course or preoperative status of the congenital heart disease were 35 patients, while palliative or corrective surgery was performed in 48 patients. Supraventricular tachycardia was based on a total of 63 congenital arrhythmogenic substrates, among them were 53 accessory pathways, 4 Mahaim fibres, 5 functionally dissociated AV-nodes and an anatomically doubled specific conduction system including 2 distinct AV-nodes in one case. In the remaining patients with tachycardia based on acquired arrhythmogenic substrates there were 45 incisional atrial reentrant tachycardias, 15 atrial flutters of the common type and 6 ectopic atrial tachycardias. In a total of 105 sessions 78 of the 83 patients were successfully treated with the use of radiofrequency current ablation. There were no significant procedure related complications. Radiofrequency current ablation can be carried out safely and successfully for the treatment of supraventricular tachycardia in young and adult patients with congenital heart disease. As such therapeutic strategy meets the specific requirements of this patient cohort, early consideration for this therapy is recommended.

Pathologic anatomy of corrected transposition of the great arteries: medical and surgical implications

BACKGROUND

Because the double-switch operation (atrial switch plus arterial switch) has recently become feasible in selected patients with congenitally physiologically corrected transposition of the great arteries, a detailed understanding of the pathologic anatomy is now mandatory for cardiologists, radiologists, and surgeons.

METHODS

A detailed study of the pathologic anatomy, the clinical implications, and the surgical implications was undertaken on 33 postmortem cases with two ventricles. A companion study was also performed of 44 postmortem cases with functionally only one ventricle. Hence this was an investigation of 77 postmortem cases.

RESULTS

Three main anatomic types of corrected transposition of the great arteries (TGA) with two ventricles were found: (1) TGA with solitus atria (S), L-loop ventricles (L), and L-TGA (L), that is, TGA [S,L,L] in 31 cases (94%); (2) TGA with solitus atria (S), L-loop ventricles (L), and D-TGA (D), that is, TGA [S,L,D] in 1 case (3%); and (3) TGA with inverted atria (I), D-loop ventricles (D), and D-TGA (D), that is, TGA [I,D,D] in 1 case (3%). Associated malformations resulted in 13 anatomic subtypes. In classical corrected TGA [S,L,L] with two ventricles, anomalies of the left-sided systemic tricuspid valve were present in 97%, with malformations of the left-sided systemic right ventricle in 91%.

CONCLUSIONS

The findings in corrected TGA with two ventricles and in cases with single ventricle support the view that anatomic repair such as the double-switch procedure, or left-sided right ventricle bypass such as the modified Norwood procedure followed by the modified Fontan procedure, is indicated in selected patients.

Radiofrequency ablation of accessory pathways associated with congenital heart disease

The coexistence of significant congenital cardiac disease with accessory pathways is not uncommon, and presents a number of issues for clinical management. These issues include the propensity of such patients to have poorly tolerated tachycardia; the difficulties in choosing appropriate medical management given potential problems with preexisting sinus node disease, poor contractility, and the possibility of proarrhythmia; the need to seriously consider ablation prior to, or at the time of, intracardiac repair of congenital cardiac defects; and finally, the difficulties that complex anatomy may pose to the interventional electrophysiologist. Definitive management requires expertise both in electrophysiology and in pediatric cardiology. Success can usually be achieved with a careful, anatomically precise approach, combined with imagination and persistence. Because of the difficulties with medical management, catheter ablation may be the most attractive modality for control of accessory pathway tachycardia in this patient population.

Rhythm and conduction disturbances in isolated, congenitally corrected transposition of the great arteries

The incidence and types of rhythm and conduction disturbances in 11 male and 6 female patients with congenitally corrected transposition of the great arteries and no other intrinsic complicating anomalies were studied. Patient age ranged from 5 to 54 years; follow-up ranged from 5 to 37 years. Surface electrocardiograms were recorded in each patient; 15 also underwent 24-hour Holter monitoring and 10 underwent electrophysiologic study. The conduction system of a 54-year-old woman who died suddenly, with complete atrioventricular (AV) block since age 30 years, was studied by serial histologic sections. Fifteen patients were asymptomatic and 2 reported repeated episodes of palpitation since childhood. Ten patients presented with a normal PR interval and 2 with first-degree AV block (12%). Five patients had complete AV block (29%), but none had had it at birth; first- and second-degree AV block preceded complete AV block in 2 patients. The morphologic pattern and duration of QRS suggested a junctional rhythm in 4 patients and an idioventricular pacemaker in 1 patient. Electrophysiologic studies confirmed that the complete AV block site was supra-Hisian in 2 patients and proximal to the His bundle bifurcation in 1 patient. However, histologic investigation disclosed fibrosis and disruption of the proximal nonbifurcating His bundle in the patient who died suddenly. In 2 patients with recurrent supraventricular tachycardia, electrophysiologic studies suggested reentry through James fibers (or dual AV nodal pathway) in 1 and the presence of a left lateral accessory AV pathway in the other. Holter monitoring showed a high incidence of ventricular arrhythmias.

The electrophysiologic basis and management of symptomatic recurrent tachycardia in patients with Ebstein's anomaly of the tricuspid valve

Twenty-two patients with Ebstein's anomaly were evaluated because of recurrent tachycardia. A total of 30 accessory pathways were present in 21 of the 22 patients. Twenty-six accessory pathways were of the atrioventricular (A-V) type while four were Mahaim fibers. Multiple accessory pathways were present in eight patients. Twenty-five of the 26 accessory A-V pathways were right-sided, either in the posterior septum (12 pathways) or the posterolateral free wall (13 pathways); one patient with corrected transposition of the great arteries had a left-sided accessory A-V pathway in a lateral free wall location. Patients with accessory A-V pathways had a long minimal ventriculoatrial (V-A) conduction time during reciprocating tachycardia (192 +/- 47 ms) and usually showed a persistent complete or incomplete right bundle branch block morphology. At surgery, preexcitation was invariably localized to the atrialized ventricle. The long V-A conduction time during reciprocating tachycardia appeared to consist of late activation of the local ventricle in the region of the accessory pathway with a further delay occurring before excitation of adjacent atrium presumably due to conduction over the accessory pathway. Accessory A-V pathways were successfully sectioned with no deaths in 13 of 15 patients. On the basis of these data, certain electrocardiographic findings encountered in the study of patients with recurrent tachycardia should point to the possibility of associated Ebstein's anomaly: morphology of the surface electrocardiogram suggesting preexcitation of the right posterior septum or right posterolateral free wall as well as the combination during reciprocating tachycardia of a long V-A interval and right bundle branch block.

Electrophysiologic evaluation and surgical correction of Wolff-Parkinson-White syndrome in children

The Wolff-Parkinson-White syndrome is due to a congenital heart malformation that is the result of one or more persistent anomalous atrioventricular pathway(s). While supraventricular tachycardia is the most commonly associated arrhythmia, there is a wide spectrum of associated arrhythmias including fatal ventricular fibrillation. It is now known that surgical ablation of the anomalous pathway(s) can result in complete cure of arrhythmias in some patients. The purpose of this report is to describe the current methods used for the preoperative and operative electrophysiologic evaluation and surgical treatment in children with the Wolff-Parkinson-White syndrome, as illustrated by the case presentation of a normal eight-year-old patient who had ventricular fibrillation.