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Experience gained from interruption of 45 anterior and posterior septal Kent bundles has permitted the formulation of a safe surgical approach to the anterior and posterior divisions of the septal area. To clarify the surgical anatomy of this difficult region, the posterior space has been likened to a trihedral pyramid, toppled on its side, with the apex the right fibrous trigone, the right and left atria making two of its sides, and the muscular ventricular septum and the left ventricle or third side, the floor. The pyramidal space contains fat, the atrioventricular (AV) nodal artery, and coronary sinus. The anterior division extends from the right fibrous trigone anteriorly to the free wall. The right atrium is connected to the anulus fibrosus, which rests upon the muscular septum and infundibulum. The AV node and His bundle are protected from dissections in both divisions by the atrial septum and right fibrous trigone. The cases of 31 patients with posterior septal Kent bundles in whom interruption was attempted resulted in division in 20, forced His division in four, and failure in seven. Elective His interruption was done in three. Success occurred in the last 10. Three failures at interruption occurred in 14 anterior septal Kent bundles.

Between July 1, 1980, and April 1, 1985, 118 patients underwent operation for correction of the Wolff-Parkinson-White syndrome. There were 72 male and 46 female patients with ages ranging from 9 months to 70 years (mean 28 +/- 6 years). The major indications for operation were medical refractoriness or drug intolerance (60%) and previous cardiac arrest (14%). Associated abnormalities included Ebstein's anomaly (12%), other arrhythmias (34%), coronary artery disease (6%), cardiomyopathy (6%), and congenital heart disease other than Ebstein's anomaly (22%). Two patients had undergone operations for Wolff-Parkinson-White syndrome previously at other institutions. Twenty percent of patients had multiple (two to four) accessory pathways, a total of 149 pathways being present in the 118 patients. Distribution of the accessory pathways was as follows: 58% left free wall, 24% posterior septal, 13% right free wall, and 5% anterior septal. The surgical technique employed previously for the Wolff-Parkinson-White syndrome and for the first 10 patients in the present series was modified in August, 1981, to include 2.5 power optical magnification, exclusive use of the endocardial approach under cardioplegic arrest, wider margins of surgical dissection, sharp dissection of the involved valve anulus, division of only the ventricular insertion of the accessory pathway, and internal identification of the ventricular epicardial peel in all regions of dissection. Of the 149 accessory pathways present, 148 were successfully divided in the 118 patients and, by means of the above modifications, 137 of 137 accessory pathways have been divided successfully in the last 108 patients in the series. The surgical results in these patients document an increase in the success rate for division of accessory pathways from 86% to 99.3%, a decrease in the reoperation rate from approximately 15% to 0%, and a decrease in the incidence of permanent complete heart block from 10.5% to 0.8%. The mortality was 5.0% in the entire series, but only one death occurred following elective operation in the absence of associated cardiac abnormalities (0.8%). Using the present surgical technique, these results suggest that surgical therapy is a conservative alternative to a lifetime of medical therapy in young, otherwise healthy patients with the Wolff-Parkinson-White syndrome.

The report relates experience with six patients with Kent bundles, five of whom had the Wolff-Parkinson-White syndrome, operated upon for tachyarrhythmias caused by the presence of the pathway. It was successfully divided in four patients, its antegrade conduction capacity interrupted in one, and a failure occurred in the sixth patient. In the three patients who had a Kent bundle with a short effective refractory period for antegrade conduction, the life-endangering potential of the Kent pathway was corrected. To emphasize the complexities of the tachyarrhythmias in Ebstein's anomaly, two patients have mild but controllable postoperative supraventricular tachyarrhythmias (SVT) due to a Mahaim pathway. The surgical problems encountered in these patients are reviewed.

This report relates the surgical experience with 79 patients with arrhythmias who had 82 left free wall accessory pathways of atrioventricular conduction of the Kent type. The current operation for the interruption of the pathway consists of two steps. First, the localization of the pathway is done by mapping the epicardial excitation sequence of the atria and the ventricles. This is followed by a set group of maneuvers needed to divide the pathway, which is not visible or palpable. First, an endocardial atrial incision is made just above the anulus fibrosus extending 1.5 to 2.0 cm on each side of the pathway's crossing point. Then, a wide separation of the coronary sulcus fat from the atria and ventricles is done. Finally, superficial fibers of the ventricular myocardium are separated from the anulus fibrosus. The surgical problems such as the possible coronary sinus origin of a pathway and the proximity of pathways to the left fibrous trigone are discussed, both from the electrophysiological and the surgical standpoints. The overall success rate for interruption of left free wall pathways has been 90% with no failure in the last 34 patients.

In this report, we have outlined our experiences with the direct surgical treatment of 16 patients with supraventricular tachyarrhythmias (SVTA). Re-entry supraventricular tachycardia (SVT) was demonstrated by the 4 patients who had retrograde-conducting Kent pathways. The SVT was corrected by the successful division of the Kent bundle in 3 and a partially successful His bundle division in one patient. The remaining 9 patients with re-entry, which included 6 with Kent pathways and WPW, all had His bundle section. The remaining 3 with His interruption had focal tachycardias associated with dysfunction of the atrioventricular (AV) node. Of the 13 His bundle interruptions, nine were successful, three resulted in questionable AV conduction, and one failed. Problems with suture ligation and cautery explained the failures. Cryothermia was the most successful procedure used. However, excision of that portion of the atrium containing the AV node shows promise of being satisfactory. The possibility is discussed of using measures much more precise and less destructive than His bundle interruption for SVTA.

Thirty-six accessory pathways of atrioventricular conduction of the Kent type were found in 17 patients in a series of 161 patients subjected to direct operation for arrhythmias caused by the pathways. Careful preoperative studies detected the multiple pathways in 11 patients. In four patients, the additional pathways were found at operation, and in two patients they were found after operation. The operation successfully interrupted 32 of the 36 pathways. Multiple pathways must be sought for in all patients who are operated upon for arrhythmias caused by accessory pathways.

The development of the procedure for interruption of a Kent bundle for the correction of the tachyarrhythmias associated with the Wolff-Parkinson-White syndrome has been hampered by the lack of anatomic descriptions of the pathways. Only 21 descriptions are given in enough detail for guidance to the surgeon. Our experience with our first 100 patients operated upon for serious dysrhythmias associated with Kent bundles has supplemented this information. In our first 40 patients the Kent was divided in 22 of 39, one having elective and four having forced interruption of the His bundle, with success in 28. In the next 60 the Kent was divided in 52 of 59 attempts, one had elective and three had forced His bundle interruption, and the success rate was 56 of 60 patients. This increased success occurred because we learned the following: (1) The anomalous pathways are best approached through the atrium and can be for out in the fat, even subepicardial in the coronary sulcus or adjacent to the anulus. (2) Interruption should be started with an incision made just above the anulus fibrosus. (3) Posterior septal pathways can be adjacent to the His bundle or in the septum from this point posteriorly to the crux. (4) Anterior septal pathways can be divided and the His bundle protected. The details for the approach to the right and left free wall, posterior septal, and anterior septal pathways will be given. The approach to all pathways is now safe enough to allow the surgeon to offer this operation to patients with life-threatening tachyarrhythmias as well as the ones with rhythm disturbances that are either burdensome or impossible to treat medically.

Nonischemic ventricular tachycardia most commonly arises in the right ventricular free wall and is frequently refractory to medical therapy. Many different types of surgical procedures have been employed to treat medically refractory nonischemic ventricular tachycardia arising in the right ventricle, but the results of these procedures have been less than optimal. The majority of these surgical procedures have been directed toward ablation of the site (or sites) of origin of the tachyarrhythmia and have failed because of the frequent occurrence of multifocal or polymorphic ventricular tachycardia in these patients. We first employed localized surgical isolation procedures to control nonischemic ventricular tachycardia arising in the right ventricular free wall in 1979. These localized procedures evolved into the development of a technique for isolating the entire right ventricular free wall from the remainder of the heart to control ventricular tachyarrhythmias arising from multiple sites in the right ventricle. Case histories are reported of two patients who underwent localized isolation procedures in 1979 as well as two patients who underwent total disconnection of the right ventricle in 1982. The follow-up period in these four patients ranges from 2 to 5 years and the control of their tachyarrhythmias has been uniformly successful. However, surgical isolation of the entire right ventricular free wall has resulted in progressive dilatation of the right ventricle as documented by serial echocardiography. The pathophysiology of the progressive right ventricular dilatation postoperatively is discussed in terms of etiology and prevention, and the indications for application of localized and total isolation procedures for nonischemic right ventricular tachycardia are outlined.