Ann Thorac Surg 2002;73:661-663
© 2002 The Society of Thoracic Surgeons
Case report
Modification of the radial procedure in a patient with partial atrioventricular septal defect
Takashi Nitta, MD*a,
Hitoshi Yamauchi, MDa,
Naoko Ohkubo, MDa,
Yosuke Ishii, MDa,
Shigeo Tanaka, MDa,
Meiso Hayashi, MDb,
Yoshinori Kobayashi, MDb,
Teruo Takano, MDb
a Department of Cardiothoracic Surgery, Nippon Medical School, Tokyo, Japan
b Department of Cardiology, Nippon Medical School, Tokyo, Japan
Accepted for publication May 17, 2001.
* Address reprint requests to Dr Nitta, Department of Cardiothoracic Surgery, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan
e-mail: nitta_takashi_surg2{at}nms.ac.jp
 |
Abstract
|
|---|
We successfully cured atrial fibrillation while preserving internodal conduction in a patient with a partial atrioventricular septal defect. Because the anterior and middle internodal tracts are interrupted by the defect, the lower right atrial incision of either the maze or the radial procedure may interrupt the remaining posterior tract, resulting in internodal conduction block. We deleted the posterior septal incision from the radial procedure and replaced it with a right-side left atriotomy. The patient resumed normal sinus rhythm with significant contraction of the right and left atria. The preserved internodal pathway through the posterior interatrial septum was confirmed by electrophysiologic study.
|
Introduction
|
|---|
Atrial fibrillation (AF) is frequently complicated in adult patients with congenital heart disease [1, 2]. In patients with an atrioventricular septal defect (AVSD), completion of the maze or the radial procedure may result in interatrial conduction block [3, 4]. This is because the anterior and middle internodal tracts are interrupted by the defect as they course from the sinus node to the atrioventricular node [5, 6], and the lower right atrial incision and the septal incision interrupt the remaining posterior tract. We successfully cured AF while preserving the internodal conduction by modifying the radial procedure in a patient with mitral valve regurgitation and atrial fibrillation associated with a partial AVSD.
A 41-year-old man was referred for congestive heart failure due to severe mitral valve regurgitation and AF. He had undergone an operation to close the partial AVSD at the age of 8. The cleft on the anterior mitral valve leaflet was not closed during that procedure because the valve regurgitation was trivial at that time. We performed a modified radial procedure and mitral valve replacement on April 25, 2000. The location of the atrial incisions and the cryolesions is schematically drawn in Figure 1. In order to avoid internodal conduction block, the posterior septal incision was deleted from the radial procedure. Instead, the left atrium was opened through a right-side left atriotomy. This incision was extended inferoposteriorly toward the commissure between the middle and posteromedial scallops of the mitral valve. The left atrial appendage was excised, and the incision was extended toward the anterior left atrium between the right and left upper pulmonary veins. The posterior left atrium around the right and left pulmonary vein orifices was cryoablated circumferentially in order to block propagation of the focal activation arising in the pulmonary veins. The cryolesions were connected to the upper or lower left atriotomies to avoid reentrant activation around the pulmonary veins. The right atrial incisions were the same as in the radial procedure. A complete mitral valve cleft was present. The mitral valve leaflets were severely thickened and were replaced with an ATS valve (ATS Medical Inc, Minneapolis, MN). The patient was cured of AF, but he required ventricular pacing for complete atrioventricular block postoperatively. On postoperative day 4, normal sinus rhythm and atrioventricular conduction resumed, and the pacing was terminated. Otherwise, the postoperative course was uneventful.
View larger version (43K):
[in this window]
[in a new window]
|
Fig 1. Radial procedure (left) and its modification for partial atrioventricular septal defect (AVSD) (right). The upper and middle schemas represent the superior and posterior epicardial views of the atria. The lower schemas represent the right-side endocardial view of the interatrial septum. The dotted lines indicate the atrial incisions, and the small circles indicate the cryolesions at the atrioventricular valve annuli. The other gray areas represent the excised left atrial appendage and cryolesions encircling the pulmonary vein orifices. Arrows represent the activation sequence during sinus rhythm. The sinus node is depicted as a gray area at the junction of the right atrium and superior vena cava. The atrioventricular node is depicted as a gray area at the interatrial septum inferior to the patch attached to the partial AVSD. In the radial procedure, the activation wavefronts from the sinus node are blocked by the lower right atriotomy, AVSD, fossa ovalis (FO), and posterior septal incision. Deleting the posterior septal incision from the radial procedure allowed the sinus impulse to propagate to the atrioventricular node while eliminating all possible macroreentry. (CS = coronary sinus; IVC = inferior vena cava; LAA = left atrial appendage; MV = mitral valve; RAA = right atrial appendage; STL = septal tricuspid leaflet; SVC = superior vena cava; TV = tricuspid valve.)
|
|
Electrophysiologic study was performed 3 months after the operation. Atrial fibrillation was not inducible by programmed electrical stimulation or by atrial burst pacing. The sinus node function was normal. The right atrial endocardium was mapped by means of a basket catheter carrying 25 bipolar electrodes. The map demonstrated that the activation that arose from the sinus node came around the superior vena cava and reached the top of the interatrial septum, then propagated downward through the posterior septum and forward above the orifice of the inferior vena cava, finally reaching the atrioventricular node (Fig 2).
The PR interval measured 228 milliseconds on the electrocardiogram, and the conduction time from the sinus node region to the atrioventricular node region was prolonged 138 milliseconds. No slow conduction was seen in the pathway. Both the right and left atrial transport functions were demonstrated by Doppler echocardiography. The patient has remained in normal sinus rhythm without any antiarrhythmic drugs for a postoperative period of 10 months.
View larger version (39K):
[in this window]
[in a new window]
|
Fig 2. Postoperative activation maps of the right atrial endocardium during sinus rhythm. The endocardial surfaces of the lateral right atrium (right) and right-side interatrial septum (left) observed from outside the atrium are shown. The atrial incisions are shown, and the arrows indicate the activation wavefronts during sinus rhythm. The sinus impulse reached the top of the septum, propagated downward through the posterior septum, went forward above the orifice of the inferior vena cava, and finally reached the atrioventricular node. The internodal conduction time was 138 ms. (AVN = atrioventricular node; FO = fossa ovalis; IVC = inferior vena cava; RAA = right atrial appendage; SAN = sinoatrial node; SVC = superior vena cava.)
|
|
|
Comment
|
|---|
We successfully cured AF and prevented internodal conduction block in a patient with a partial AVSD. In patients with an AVSD, the anterior and middle internodal tracts are either interrupted or grossly distorted as they course through the interatrial septum [6]. Although the internodal tracts are not histologically specialized pathways, the posterior tract, which courses down the crista terminalis and traverses the lower right atrium, remains as a conduction pathway from the sinus node to the atrioventricular node. In the maze or the radial procedure, the posterior internodal tract is interrupted by the incision at the lower right atrium [3, 4]. Therefore, completion of the maze or the radial procedure may result in internodal conduction block, necessitating pacemaker implantation. Simply deleting the lower right atrial incision from these procedures preserves the posterior internodal tract but forms a circular reentrant pathway around the tricuspid valve and predisposes the patient to a common-type atrial flutter. Instead, we deleted the posterior septal incision to allow the posterior septum to act as a conduction pathway from the sinus node to the atrioventricular node. This modification allowed preservation of the internodal conduction and elimination of all possible macroreentry.
Transient atrioventricular block occurred immediately after the operation, and the PR interval and internodal conduction time were prolonged postoperatively in this patient. In patients with an AVSD, the longer length of the posterior internodal tract compared to the anterior or middle tract has been shown to be the cause of the prolonged PR interval in the electrocardiogram [6]. The postoperative endocardial map directly demonstrated the internodal conduction pathway through the posterior interatrial septum without any slow conduction on the pathway. The incidence of atrioventricular block after surgical repair of AVSD has been reported to be 1.2% to 5.1% [7, 8]. Careful monitoring for atrioventricular block should be continued in patients after correction of AVSD.
Atrial structural anomalies specific to the underlying defect should be considered in surgical procedures for AF associated with congenital heart disease. In patients with atrial septal defect, the anterior internodal tract is intact and serves as the dominant pathway for internodal conduction. Therefore, there would be little chance for internodal conduction block to occur even after the posterior interatrial septum is incised [9]. More complex anomalies such as single atrium, particularly when the interatrial septum is involved, may carry a risk of internodal conduction block when the patient undergoes surgical treatment for AF. It is extremely important to take the atrial conduction routes into account in order to prevent a conduction disturbance when performing surgical treatment for AF in patients with congenital heart disease.
|
References
|
|---|
-
Vetter V.L., Horowitz L.N. Electrophysiologic residua and sequelae of surgery for congenital heart defects. Am J Cardiol 1982;50:588-604.[Medline]
-
Hynes J.K., Tajik A.J., Seward J.B., et al. Partial atrioventricular canal defect in adults. Circulation 1982;66:284-287.[Abstract/Free Full Text]
-
Cox J.L., Jaquiss R.D., Schuessler R.B., Boineau J.P. Modification of the maze procedure for atrial flutter and atrial fibrillation, II: surgical technique of the maze III procedure. J Thorac Cardiovasc Surg 1995;110:485-495.[Abstract/Free Full Text]
-
Nitta T., Sakamoto S., Miyagi Y., et al. Initial experience with the radial incision approach for atrial fibrillation. Ann Thorac Surg 1999;68:805-811.[Abstract/Free Full Text]
-
James T.N. The connecting pathways between the sinus node and A-V node and between the right and the left atrium in the human heart. Am Heart J 1963;66:498-508.[Medline]
-
Waldo A.L., Kaiser G.A., Bowman F.O., Jr, Malm J.R. Etiology of prolongation of the P-R interval in patients with an endocardial cushion defect: further observations on internodal conduction and the polarity of the retrograde P wave. Circulation 1973;48:19-26.[Abstract/Free Full Text]
-
Goldfaden D.M., Jones M., Morrow A.G. Long-term results of repair of incomplete persistent atrioventricular canal. J Thorac Cardiovasc Surg 1981;82:669-673.[Abstract]
-
El-Najdawi E.K., Driscoll D.J., Puga F.J., et al. Operation for partial atrioventricular septal defect: a forty-year review. J Thorac Cardiovasc Surg 2000;119:880-889.[Abstract/Free Full Text]
-
Kobayashi J., Yamamoto F., Nakano K., Sasako Y., Kitamura S., Kosakai Y. Maze procedure for atrial fibrillation associated with atrial septal defect. Circulation 1998;19(Suppl II):399-402.
Top
Abstract
Introduction
