13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

RT-92

Antiarrhythmic surgery for treatment of atrial fibrillation

Hans Kottkamp, Gerhard Hindricks, Dieter Hammel, Jörg Mergenthaler, Martin Borggrefe, Hans H. Scheld, Günter Breithardt.
Hospital of the Westfälische Wilhelms-University, Department of Cardiology and Angiology, Institute for Arteriosclerosis Research, Münster, Germany

Surgical procedures for treatment of atrial fibrillation

Left atrial isolation

Williams and coworkers² reported in 1980 on the left atrial isolation procedure. Surgical incisions result in complete electrical isolation of the body of the left atrium from the rest of the heart. Thereby, the isolated left atrium may develop its own rhythm that is asynchronous to the right atrial rhythm and does not interfere with atrioventricular conduction. The left atrial isolation procedure has been primarily developed for treatment of ectopic left atrial tachycardia. In cases with persistent left atrial fibrillation, the sinus node can still act as a normal pacemaker and conduction through the right atrium to the atrioventricular node is also preserved. Therefore, the normal regularity of the heart beat during sinus rhythm may be preserved. On the other hand, persistent left atrial fibrillation still carries the risk of thrombus formation within the left atrial appendage and the concomitant risk of thromboembolism and stroke necessitating continuation of anticoagulant therapy.

Corridor procedure

In 1985, Guiraudon and coworkers³ introduced a surgical procedure for treatment of atrial fibrillation with separation of the right atrium from the left atrium by incising the atrial septum. A small part of the lateral free wall of the right atrium is excluded from the isolation. Thereby, a broad conduit is constructed that permits conduction from the sinus node area through the atrial septum towards the atrioventricular node. In addition, the left and right atrial appendages are removed^3-5. The purpose of the creation of this corridor is to restore a regular rhythm to the ventricles that is driven by normal sinus rhythm with physiologic chronotropic response. This operation permits the left atrium to fibrillate. On the other hand, the reduction of the right atrial mass should inhibit atrial fibrillation within the corridor. The thromboembolic vulnerability with the risk of stroke is not relieved by the corridor operation and patients still need oral anticoagulation for prevention of thromboembolism. In addition, the hemodynamic compromises associated with atrial fibrillation are not improved.

Recently, van Hemel et al⁶ reported on the long-term follow-up of 30 patients who had undergone the corridor operation for lone paroxysmal atrial fibrillation and who had normal preoperative sinus node function. Five years after surgery, the actuarial proportion of patients with recurrence of atrial fibrillation within the corridor was 8 ± 5%, with new atrial arrhythmias consisting of atrial flutter and atrial tachycardia in the corridor 27 ± 8%, and with sinus node dysfunction requiring pacing therapy 13 ± 6%⁶. Overall, the actuarial arrhythmic event rate was 48% at 5 years. In patients without recurrence of atrial fibrillation and normal sinus node function, right atrial transport was preserved in 69%. Van Hemel and coworkers discussed that the presumed ongoing atrial disease that constitutes the arrhythmogenic substrate for atrial fibrillation may affect the electrophysiologic properties of the atria and may provoke new arrhythmic events⁶.

Maze procedure

In 1991, Cox and coworkers⁷ reported on their initial experience with a surgical procedure that is based on the principle of an electrical maze. Surgical incisions are employed to reduce the contiguous atrial tissue mass that is available for reentrant circuits in atrial fibrillation. In their approach, both atrial appendages are excised and the pulmonary veins are isolated. The atrial incisions are properly placed to guide the elctrical impulse from the sinus node area to the atrioventricular node along a specified route^7,8. In addition, the sinus impulse is directed to the entire right and left atrium except for the atrial appendages and pulmonary vein area through multiple blind alleys that are created by a series of long insulating atrial incisions. The design for the maze procedure therefore not only aims at regu-larization of the heart beat but also at relief of the vulnerability to thromboembolism and preservation of atrial transport function. The maze procedure has been modified twice by Cox and coworkers with a significant improvement in outcome^7,8.

In their five-year experience paper, Cox et al⁸ reported on the outcome of 75 patients with a mean age of 52 years who had undergone the maze procedure. In 65 of their patients, the follow-up period was at least 3 months after surgery with a range of 3 to 63 months. One patient died 10 days after a combined maze procedure and operation for hypertrophic obstructive cardiomyopathy. The maze procedure cured atrial fibrillation without the need for antiarrhythmic medication in 58 of 65 patients (89%) and with medication in 64 of 65 patients (98%). In 28% of the patients, concomitant cardiac procedures were performed in addition to the maze procedure. In patients who underwent only the maze procedure and had not had previous surgical treatment (n = 49), the cardiopulmonary bypass time averaged 184 minutes and the aortic cross clamping time 69 minutes^7,8. Postoperative atrial pacemakers were required in 40% of the patients, 26% for preoperative sick sinus syndrome, 6% for iatrogenic injury of the sinus node, and 8% had pacemakers in place preoperatively.