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Repair of Corrected Transposition Associated with Ventricular Septal Defect and Pulmonary Stenosis
Repair of Corrected Transposition Associated with Ventricular Septal Defect and Pulmonary Stenosis Florentino J. Vargas, M.D.,* Guillermo 0. Kreutzer, M.D., Andres J. Schlichter, M.D., Miguel A. Granja, M.D., and Eduardo A. Kreutzer, M.D. ABSTRAn Five patients with the diagnosis of classically corrected transposition of the great arteries, ventricular septal defect (VSD), and pulmonary outflow tract obstruction underwent surgical repair. A variant of a previously described technique was used to avoid injury to conduction tissue. Through an incision into the anatomical left ventricle, the VSD patch was sutured inferiorly to the right and away from the edges of the defect and superiorlyto the epicardial border of the ventriculotomy. The pulmonary artery was opened, and its proximal end was closed with a suture. A pouch containing the conduction tissue was therefore obtained. Pulmonary ventriculoarterial continuity was reestablished using a valved or nonvalved Dam n or pericardial conduit. The postoperative course of the patients was uneventful. No changes were demonstrated on comparison with preoperative cardiac rhythm. Good hemodynamic performance was noted in 2 patients in whom postoperative catheterizationwas performed.
Atrioventricular discordance is usually associated with ventriculoarterialdiscordance. This combination is commonly called congenitally corrected transposition of the great arteries (CTGA). Although CTGA may exist without other intracardiac malformations, associated anomalies are frequently present, including ventricular septal defect (VSD), pulmonary outflow tract obstruction (POTO), or anatomical tricuspid valve regurgitation [l51. When both VSD and POTO are present, surgical repair may present difficulties in that closure of the defect and release of the subpulmonary obstruction carry the risk of injury to the conduction tissue. A more detailed knowledge of the anatomy and location of the His bundle led to the development of surgical techniques devoted to preserve its integrity. Satisfactory results have already been achieved in the treatment of these combined anomalies [6-161. Since 1978, we have successfully operated on 5 patients with CTGA, VSD, and POTO using a procedure that is based on the same principle as that previously described by Marcelletti and colleagues [12,13, 15, 161. The VSD is closed such that both great arteries are From the Division of Cardiovascular Surgery, Hospital de N3os and Clinica Baztemca, Buenos Aires, Argentina. Accepted for publication Feb 8, 1985. Address reprint requests to Dr.F. J. Vargas, Clinica Baztemca, Juncal 3002, Buenos Aires 1425, Argentina. ‘Currently Graham Fellow of The American Association for Thoracic Surgery at the Department of Cardiovascular Surgery, Children’s Hospital of Boston, Harvard Medical School, Boston, MA.
excluded from the venous ventricle. After closure of the previously transected pulmonary artery, pulmonary ventriculoarterialcontinuity is reestablished with a conduit. The tailoring of the patch, however, is carried out in a different manner. Since the endocardial surface of the anterior superior wall of the anatomical left ventricle can be potentially dangerous because of the risk related to the presence of conduction tissue in a subendocardial location, we suture the patch superiorly to the border of the ventriculotomy. A pouch of the systemic ventricle is thereby created that contains the blind outflow of the pulmonary ventricle and, thus, the area where the penetrating His bundle is located.
Patients and Methods Three boys and two girls ranging in age from 2 to 7 years were operated on at Children’s Hospital of Buenos Aires from August, 1978, through July, 1982. The clinical impression of CTGA, VSD, and POTO was confirmed during a hemodynamic and angiocardiographicevaluation in all of the patients. None had evidence of right atrioventricular valve regurgitation. The nature of the pulmonary ventricular outflow obstruction was subpulmonary alone in 2, and combined subpulmonaryand valvular in 3. In all patients, the temperature was lowered at operation to 25”C, and aortic crosstlamping was performed under cold crystalloid potassium cardioplegia. After previous identification of the anterior papillary muscle through the right atrium, an oblique ventriculotomywas performed in between the overlying right coronary artery and the apex (Fig 1). The VSD and the subpulmonary area were exposed, and a Teflon patch was used to exclude the VSD and the subpulmonary outflow tract from the remaining chamber of the pulmonary ventricle. A running suture that started 10 mm below the inferior edge of the VSD was directed posteriorly to the superior border of the ventriculotomy; in this way, a part of the patch was attached to the base of the adjoining mitral valve leaflet (see Fig 1). The sutures were placed anteriorly in the septum, away from the VSD, and were also directed to the ventriculotomy. Finally, both the superior edges of the ventriculotomyand the patch were oversewn. In the fvst 3 patients in the series, the pulmonary artery was opened vertically and the pulmonary valve leaflets sutured together from inside with a double running suture. In the last 2, the pulmonary artery was transected and the proximal stump oversewn. In the first patient we operated on, pulmonary ventriculoarterial continuity was reestablished with a 19mm nonvalved Dacron conduit. In the second patient, an 18-mm xenograft valved conduit was used. A non-
510 The Annals of Thoracic Surgery Vol 40 No 5 November 1985
Fig 2. Patient 4. (A)Postoperative systemic ventriculogram showing the systemic right ventricular chamber (SV)and the aorta (AO). Arrow points to a superiorly placed pouch thut connects with the SV. ( B ) Diagram of same structure shows a conduit interposed between the pulmonary artery and the pulmonary zmtricle (W).The proximal stump of the pulmonary artery has been OveTSewn (S).
triculograms showed a sharply defined pouch in the apical part of the interventricular septum in continuity with the systemic ventricular chamber (Fig 2).
Comment Fig I. Repair of corrected transposition of the great arteries with mtricular septal defect (vsd) and pulmonary outflow tract obstruction (POTO). (A)Incision of the anatomical left ventricle (dashed line) is performed after previous identification of the mitral valve attachment through the right atrium. (B) The V S D is exposed through the ventriculotomy. The suture ofthe patch (dashed line) stays to the right and away from the border of the VSD. Through a vertical incision in the pulmonary artery, the free edges of the pulmonary valve leaflets (pvl)are sutured together (in the last 2 patients, the pulmonary artery was transected and the proximal end closed with a suture). (C) A large T@on patch is attachedfrom 10 mm below the V S D to the epicardial border of the mtriculotomy. I t must therefore be sutured to the mitral valve leaflet (M)posteriorly and to the interventricular septum (away from the VSD) anteriorly. A pouch of the systemic ventricle containing the POTO and the His bundle is thereby obtained. (0)Pulmonary mtriculwrterial continuity is re-established by a conduit (COND). A 0 = aorta; PA = pulmonary artery.
valved pericardial conduit was employed in the remaining 3 patients, who were 2, 3, and 5 years old. Postoperative recovery was uneventful, and all patients were discharged from the hospital in good hemodynamic condition. None had rhythm disturbances.
Results Follow-up on the 5 patients ranges from 2 to 6 years, and 3 of them have been followed for more than 4 years. All of them are in New York Heart Association Functional Class I, free from symptoms and without medication. Hemodynamic evaluation performed in 2 patients in whom nonvalved conduits were placed showed Satisfactory cardiac performance, even though a pulmonary ventriculoarterial gradient of 25 mm H g was present in 1 child. End-diastolic pressure in the anatomical left ventricle was within normal limits in both patients. Ven-
Avoidance of injury to the bundle of His represents the main challenge in surgical management of CTGA, VSD, and POTO. Despite the extensive literature on this topic [7-161, a final conclusion cannot be made regarding the exact location of the atrioventricular bundle as detected at operation [ l l , 17, 181. Agreement exists, however, that in situs solitus, the penetrating bundle merges into the pulmonary ventricle somewhere in the area of pulmonary-mitral continuity to follow a subendocardial course along the anterior wall of the ventricle, below the pulmonary annulus [8, 91. It is therefore closely related to the anterior and superior border of the VSD and embedded within the subpulmonary obstructive tissue. Attempts to directly relieve the subpulmonary obstruction or to close the VSD by suturing the patch on the morphological left side of the septum carry a substantial risk of surgically induced heart block [19]. Interposition of a pulmonary ventriculoarterial conduit and placement of the stitches on the morphologicid right side of the septum during closure of the septal defect [ll]constitute the major advances in lowering the risk of damage to the conduction tissue when treating these associated malformations. An alternative technique has been suggested by Marcelletti and associates [16] at Mayo Clinic. They deviated the patch from the lower edge of the defect to the endocardial surface of the anterior and superior wall of the pulmonary ventricular outflow; both great arteries were thereby connected with the systemic ventricle. After closing the proximal transected pulmonary artery, they reestablished pulmonary ventriculoarterial continuity with a conduit. With this approach, the conduction system should stay to the left of the patch. Despite the attractiveness of the technique, however, objections
511 Vargas et a1 Corrected Transposition with VSD and Pulmonary Stenosis
have been made mainly because of the potential risk involved in placing sutures on the anterior and superior wall of the outflow tract of the anatomical left ventricle in the subpulmonary area, where the proximal part of the penetrating His bundle is in a vulnerable subendocardial position [ll]. Using a rationale similar to the one just described, we employed a somewhat different procedure in our 5 patients. In all of them, the patch was attached superiorly to the epicardial border of the ventriculotomy, beyond the subpulmonary, subendocardial area where the His bundle is located. Since the patch goes from the lower edge of the VSD to the epicardial border of the ventriculotomy, adequate exposure is obtained with no need for retraction of the left ventricular outflow tract, which remains hidden by the patch itself during the procedure. This minimizes the manipulation of and pressure trauma in the critical subpulmonary area. A decision has to be made concerning the use of a valved or a nonvalved conduit. A pericardial tube can be easily placed without risk of compression, even in the chest of a small infant. Also, no substantialdeposition of fibrinous tissue is expected to develop in the inner surface of the tube. These are major advantages over a valved Dacron tube [20, 211. The pulmonary regurgitation resulting from overloading an anatomical left ventricle will probably have little or no hemodynamic importance. Clinical or hemodynamic evidence of overloading an anatomical left ventricle has not been demonstrated in our patients. Nevertheless, the long-term follow-up will ultimately show if the performance of these ventricles remains normal. Use of a valved conduit may preclude such complications, but the patient will probably have to undergo reoperation in the future for replacement of the prosthesis [19]. The long-term outcome of the xenograft and homograft valved conduits seems to be deterioration of the valve and progressive obstruction of the conduit by fibrinous tissue [20-221. Our experience, as reported in this article, has been encouraging. In our small series, there has been no mortality or rhythm disturbances. In addition, the procedure itself does not present technical difficulties. Therefore, it seems valid to consider this technique as an alternative for repair of CTGA with VSD and POTO. Closure of the VSD by suturing the patch to the left aspect of the septum would be reserved for patients without POTO.
Addendum Since submission of this article, 2 additional patients were successfully operated on with the same technique. An autologous pericardial valved conduit was used to reestablish the pulmonary ventricle-pulmonary artery continuity in both.
References 1. Fontana RS, Edwards JE: Frequency of occurrence of various anatomic types of malformations. In Congenital Cardiac Diseases: Review of 357 Cases Studied Pathologically. Philadelphia, Saunders, 1962, p 40
2. Van Praagh R: Complete transposition of the great arteries. In Keith JD, Rowe RD, Vlad P (eds): Heart Disease in Infancy and Childhood. New York, Maanillan, 1%7, pp 682744 3. Williams WG, Sun R, Shindo G, et a1 Repair of major intracardiac anomalies associated with atrioventricular discordance. Ann Thorac Surg 31:527, 1981 4. Hallman GL, Gill SS, Bloodwell RD, et al. Surgical treatment of cardiac defects associated with corrected transposition of the great vessels. Circulation 35Suppl 1:133, 1967 5. Friedberg DZ, Nadar AS Clinical profile of patients with congenital corrected transposition of the great arteries. N Engl J Med 2821053, 1970 6. Westerman GR, Norwood WI, Castaneda AR: Corrected transposition: repair of associated intracardiac defects (abstract). Circulation 64:Suppl432,1981 7. El Sayed H, Qeland WP, Bentall HH, et ak Corrected transposition of the great arterial trunks. surgical treatment of the associated defects. J Thorac Cardiovasc Surg e4:443, 1%2 8. Anderson RH, Arnold R, Wilkinson J L The conducting system in congenitally corrected transposition. Lancet 1:1286,1973 9. Anderson RH, Becker AE, Arnold R, Wilkinson J L The conducting tissues in classically corrected transposition. Circulation 50:911, 1974 10. Danielson GK, McGoon DC, Wallace RB, et a1 Surgery of corrected transposition. In Anderson RH, Shineboume EA (eds): Paediatric Cardiology 1977. Edinburgh, Churchill/ Livingstone, 1978, pp 224-230 11. de Leva1 MR,Bastos P, Stark J, et a1 Surgical technique to reduce the risks of heart block followingclosure of ventricular septal defect in atrioventricular discordance. J Thorac Cardiovasc Surg 78515, 1979 12. Marcelletti C, Maloney JD, Ritter DC, et al: Corrected transposition and ventricular septal defect: surgical experience (abstract). Circulation 58.Suppl2149, 1978 13. McGoon DC:Discussion of [ll] 14. Stewart S The technique of ventricular septal defect closure in L-transposition of the great vessels. Ann Thorac Surg 23:156, 1977 15. Danielson GK Atrioventricular discordance. In Stark J, de Leva1 M (eds): Surgery for Congenital Heart Defects. London, Grune & Stratton, 1983, pp 387-395 16. Marcelletti C, Maloney JD, Ritter C, et al: Corrected transposition and VSD surgical experience. Ann Surg 191:751, 1980 17. Fox L, Kirklin J, Pacifico A, et ak Intracardiac repair of cardiac malformations with atrioventricular discordance. Circulation 54.123, 1976 18. Waldo A, Pacifico A, Bargeron L, et al: Electrophysiological delineation of the specialized AV conduction system in patients with corrected transposition of the great vessels and ventricular septal defect. Circulation 52435, 1975 19. Westerman GR, Lang P, Castaneda AR, Norwood WI:Corrected transposition and repair of associated intracardiac defects. Circulation 66.Suppl 1:1, 1982 20. Saravalli OA, Somerville J, Jefferson KE: Calcification of aortic homografts used for reconstruction of the right ventricular outflow tract. J Thorac Cardiovasc Surg 80:909,1980 21. Schlichter AJ, Kreutzer GO: Autologous pericardial valved conduit. Rev Latin Cardiol y Cir Cardiovasc Inf 1:43, 1985 22. Marcelletti C, McGoon DC, Wallace RB, Mair D D Early and late results of surgical repair of truncus arteriosus (abstract). Circulation 51:Suppl2101, 1975
Atrioventricular discordance is usually associated with ventriculoarterialdiscordance. This combination is commonly called congenitally corrected transposition of the great arteries (CTGA). Although CTGA may exist without other intracardiac malformations, associated anomalies are frequently present, including ventricular septal defect (VSD), pulmonary outflow tract obstruction (POTO), or anatomical tricuspid valve regurgitation [l51. When both VSD and POTO are present, surgical repair may present difficulties in that closure of the defect and release of the subpulmonary obstruction carry the risk of injury to the conduction tissue. A more detailed knowledge of the anatomy and location of the His bundle led to the development of surgical techniques devoted to preserve its integrity. Satisfactory results have already been achieved in the treatment of these combined anomalies [6-161. Since 1978, we have successfully operated on 5 patients with CTGA, VSD, and POTO using a procedure that is based on the same principle as that previously described by Marcelletti and colleagues [12,13, 15, 161. The VSD is closed such that both great arteries are From the Division of Cardiovascular Surgery, Hospital de N3os and Clinica Baztemca, Buenos Aires, Argentina. Accepted for publication Feb 8, 1985. Address reprint requests to Dr.F. J. Vargas, Clinica Baztemca, Juncal 3002, Buenos Aires 1425, Argentina. ‘Currently Graham Fellow of The American Association for Thoracic Surgery at the Department of Cardiovascular Surgery, Children’s Hospital of Boston, Harvard Medical School, Boston, MA.
excluded from the venous ventricle. After closure of the previously transected pulmonary artery, pulmonary ventriculoarterialcontinuity is reestablished with a conduit. The tailoring of the patch, however, is carried out in a different manner. Since the endocardial surface of the anterior superior wall of the anatomical left ventricle can be potentially dangerous because of the risk related to the presence of conduction tissue in a subendocardial location, we suture the patch superiorly to the border of the ventriculotomy. A pouch of the systemic ventricle is thereby created that contains the blind outflow of the pulmonary ventricle and, thus, the area where the penetrating His bundle is located.
Patients and Methods Three boys and two girls ranging in age from 2 to 7 years were operated on at Children’s Hospital of Buenos Aires from August, 1978, through July, 1982. The clinical impression of CTGA, VSD, and POTO was confirmed during a hemodynamic and angiocardiographicevaluation in all of the patients. None had evidence of right atrioventricular valve regurgitation. The nature of the pulmonary ventricular outflow obstruction was subpulmonary alone in 2, and combined subpulmonaryand valvular in 3. In all patients, the temperature was lowered at operation to 25”C, and aortic crosstlamping was performed under cold crystalloid potassium cardioplegia. After previous identification of the anterior papillary muscle through the right atrium, an oblique ventriculotomywas performed in between the overlying right coronary artery and the apex (Fig 1). The VSD and the subpulmonary area were exposed, and a Teflon patch was used to exclude the VSD and the subpulmonary outflow tract from the remaining chamber of the pulmonary ventricle. A running suture that started 10 mm below the inferior edge of the VSD was directed posteriorly to the superior border of the ventriculotomy; in this way, a part of the patch was attached to the base of the adjoining mitral valve leaflet (see Fig 1). The sutures were placed anteriorly in the septum, away from the VSD, and were also directed to the ventriculotomy. Finally, both the superior edges of the ventriculotomyand the patch were oversewn. In the fvst 3 patients in the series, the pulmonary artery was opened vertically and the pulmonary valve leaflets sutured together from inside with a double running suture. In the last 2, the pulmonary artery was transected and the proximal stump oversewn. In the first patient we operated on, pulmonary ventriculoarterial continuity was reestablished with a 19mm nonvalved Dacron conduit. In the second patient, an 18-mm xenograft valved conduit was used. A non-
510 The Annals of Thoracic Surgery Vol 40 No 5 November 1985
Fig 2. Patient 4. (A)Postoperative systemic ventriculogram showing the systemic right ventricular chamber (SV)and the aorta (AO). Arrow points to a superiorly placed pouch thut connects with the SV. ( B ) Diagram of same structure shows a conduit interposed between the pulmonary artery and the pulmonary zmtricle (W).The proximal stump of the pulmonary artery has been OveTSewn (S).
triculograms showed a sharply defined pouch in the apical part of the interventricular septum in continuity with the systemic ventricular chamber (Fig 2).
Comment Fig I. Repair of corrected transposition of the great arteries with mtricular septal defect (vsd) and pulmonary outflow tract obstruction (POTO). (A)Incision of the anatomical left ventricle (dashed line) is performed after previous identification of the mitral valve attachment through the right atrium. (B) The V S D is exposed through the ventriculotomy. The suture ofthe patch (dashed line) stays to the right and away from the border of the VSD. Through a vertical incision in the pulmonary artery, the free edges of the pulmonary valve leaflets (pvl)are sutured together (in the last 2 patients, the pulmonary artery was transected and the proximal end closed with a suture). (C) A large T@on patch is attachedfrom 10 mm below the V S D to the epicardial border of the mtriculotomy. I t must therefore be sutured to the mitral valve leaflet (M)posteriorly and to the interventricular septum (away from the VSD) anteriorly. A pouch of the systemic ventricle containing the POTO and the His bundle is thereby obtained. (0)Pulmonary mtriculwrterial continuity is re-established by a conduit (COND). A 0 = aorta; PA = pulmonary artery.
valved pericardial conduit was employed in the remaining 3 patients, who were 2, 3, and 5 years old. Postoperative recovery was uneventful, and all patients were discharged from the hospital in good hemodynamic condition. None had rhythm disturbances.
Results Follow-up on the 5 patients ranges from 2 to 6 years, and 3 of them have been followed for more than 4 years. All of them are in New York Heart Association Functional Class I, free from symptoms and without medication. Hemodynamic evaluation performed in 2 patients in whom nonvalved conduits were placed showed Satisfactory cardiac performance, even though a pulmonary ventriculoarterial gradient of 25 mm H g was present in 1 child. End-diastolic pressure in the anatomical left ventricle was within normal limits in both patients. Ven-
Avoidance of injury to the bundle of His represents the main challenge in surgical management of CTGA, VSD, and POTO. Despite the extensive literature on this topic [7-161, a final conclusion cannot be made regarding the exact location of the atrioventricular bundle as detected at operation [ l l , 17, 181. Agreement exists, however, that in situs solitus, the penetrating bundle merges into the pulmonary ventricle somewhere in the area of pulmonary-mitral continuity to follow a subendocardial course along the anterior wall of the ventricle, below the pulmonary annulus [8, 91. It is therefore closely related to the anterior and superior border of the VSD and embedded within the subpulmonary obstructive tissue. Attempts to directly relieve the subpulmonary obstruction or to close the VSD by suturing the patch on the morphological left side of the septum carry a substantial risk of surgically induced heart block [19]. Interposition of a pulmonary ventriculoarterial conduit and placement of the stitches on the morphologicid right side of the septum during closure of the septal defect [ll]constitute the major advances in lowering the risk of damage to the conduction tissue when treating these associated malformations. An alternative technique has been suggested by Marcelletti and associates [16] at Mayo Clinic. They deviated the patch from the lower edge of the defect to the endocardial surface of the anterior and superior wall of the pulmonary ventricular outflow; both great arteries were thereby connected with the systemic ventricle. After closing the proximal transected pulmonary artery, they reestablished pulmonary ventriculoarterial continuity with a conduit. With this approach, the conduction system should stay to the left of the patch. Despite the attractiveness of the technique, however, objections
511 Vargas et a1 Corrected Transposition with VSD and Pulmonary Stenosis
have been made mainly because of the potential risk involved in placing sutures on the anterior and superior wall of the outflow tract of the anatomical left ventricle in the subpulmonary area, where the proximal part of the penetrating His bundle is in a vulnerable subendocardial position [ll]. Using a rationale similar to the one just described, we employed a somewhat different procedure in our 5 patients. In all of them, the patch was attached superiorly to the epicardial border of the ventriculotomy, beyond the subpulmonary, subendocardial area where the His bundle is located. Since the patch goes from the lower edge of the VSD to the epicardial border of the ventriculotomy, adequate exposure is obtained with no need for retraction of the left ventricular outflow tract, which remains hidden by the patch itself during the procedure. This minimizes the manipulation of and pressure trauma in the critical subpulmonary area. A decision has to be made concerning the use of a valved or a nonvalved conduit. A pericardial tube can be easily placed without risk of compression, even in the chest of a small infant. Also, no substantialdeposition of fibrinous tissue is expected to develop in the inner surface of the tube. These are major advantages over a valved Dacron tube [20, 211. The pulmonary regurgitation resulting from overloading an anatomical left ventricle will probably have little or no hemodynamic importance. Clinical or hemodynamic evidence of overloading an anatomical left ventricle has not been demonstrated in our patients. Nevertheless, the long-term follow-up will ultimately show if the performance of these ventricles remains normal. Use of a valved conduit may preclude such complications, but the patient will probably have to undergo reoperation in the future for replacement of the prosthesis [19]. The long-term outcome of the xenograft and homograft valved conduits seems to be deterioration of the valve and progressive obstruction of the conduit by fibrinous tissue [20-221. Our experience, as reported in this article, has been encouraging. In our small series, there has been no mortality or rhythm disturbances. In addition, the procedure itself does not present technical difficulties. Therefore, it seems valid to consider this technique as an alternative for repair of CTGA with VSD and POTO. Closure of the VSD by suturing the patch to the left aspect of the septum would be reserved for patients without POTO.
Addendum Since submission of this article, 2 additional patients were successfully operated on with the same technique. An autologous pericardial valved conduit was used to reestablish the pulmonary ventricle-pulmonary artery continuity in both.
References 1. Fontana RS, Edwards JE: Frequency of occurrence of various anatomic types of malformations. In Congenital Cardiac Diseases: Review of 357 Cases Studied Pathologically. Philadelphia, Saunders, 1962, p 40
2. Van Praagh R: Complete transposition of the great arteries. In Keith JD, Rowe RD, Vlad P (eds): Heart Disease in Infancy and Childhood. New York, Maanillan, 1%7, pp 682744 3. Williams WG, Sun R, Shindo G, et a1 Repair of major intracardiac anomalies associated with atrioventricular discordance. Ann Thorac Surg 31:527, 1981 4. Hallman GL, Gill SS, Bloodwell RD, et al. Surgical treatment of cardiac defects associated with corrected transposition of the great vessels. Circulation 35Suppl 1:133, 1967 5. Friedberg DZ, Nadar AS Clinical profile of patients with congenital corrected transposition of the great arteries. N Engl J Med 2821053, 1970 6. Westerman GR, Norwood WI, Castaneda AR: Corrected transposition: repair of associated intracardiac defects (abstract). Circulation 64:Suppl432,1981 7. El Sayed H, Qeland WP, Bentall HH, et ak Corrected transposition of the great arterial trunks. surgical treatment of the associated defects. J Thorac Cardiovasc Surg e4:443, 1%2 8. Anderson RH, Arnold R, Wilkinson J L The conducting system in congenitally corrected transposition. Lancet 1:1286,1973 9. Anderson RH, Becker AE, Arnold R, Wilkinson J L The conducting tissues in classically corrected transposition. Circulation 50:911, 1974 10. Danielson GK, McGoon DC, Wallace RB, et a1 Surgery of corrected transposition. In Anderson RH, Shineboume EA (eds): Paediatric Cardiology 1977. Edinburgh, Churchill/ Livingstone, 1978, pp 224-230 11. de Leva1 MR,Bastos P, Stark J, et a1 Surgical technique to reduce the risks of heart block followingclosure of ventricular septal defect in atrioventricular discordance. J Thorac Cardiovasc Surg 78515, 1979 12. Marcelletti C, Maloney JD, Ritter DC, et al: Corrected transposition and ventricular septal defect: surgical experience (abstract). Circulation 58.Suppl2149, 1978 13. McGoon DC:Discussion of [ll] 14. Stewart S The technique of ventricular septal defect closure in L-transposition of the great vessels. Ann Thorac Surg 23:156, 1977 15. Danielson GK Atrioventricular discordance. In Stark J, de Leva1 M (eds): Surgery for Congenital Heart Defects. London, Grune & Stratton, 1983, pp 387-395 16. Marcelletti C, Maloney JD, Ritter C, et al: Corrected transposition and VSD surgical experience. Ann Surg 191:751, 1980 17. Fox L, Kirklin J, Pacifico A, et ak Intracardiac repair of cardiac malformations with atrioventricular discordance. Circulation 54.123, 1976 18. Waldo A, Pacifico A, Bargeron L, et al: Electrophysiological delineation of the specialized AV conduction system in patients with corrected transposition of the great vessels and ventricular septal defect. Circulation 52435, 1975 19. Westerman GR, Lang P, Castaneda AR, Norwood WI:Corrected transposition and repair of associated intracardiac defects. Circulation 66.Suppl 1:1, 1982 20. Saravalli OA, Somerville J, Jefferson KE: Calcification of aortic homografts used for reconstruction of the right ventricular outflow tract. J Thorac Cardiovasc Surg 80:909,1980 21. Schlichter AJ, Kreutzer GO: Autologous pericardial valved conduit. Rev Latin Cardiol y Cir Cardiovasc Inf 1:43, 1985 22. Marcelletti C, McGoon DC, Wallace RB, Mair D D Early and late results of surgical repair of truncus arteriosus (abstract). Circulation 51:Suppl2101, 1975