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Secondary left atrioventricular valve replacement in atrioventricular septal (AV canal) defect: A method to avoid left ventricular outflow tract obstruction
The Journal of Thoracic and Cardiovascular
6 3 2 Brief communications
Surgery
of these patients have done well. The third patient died of prosthetic valve endocarditis. The infrequency of operative treatment no doubt has reflected the generalized nature of the endocardial fibrosis in most patients. Surgical intervention for diffuse endomyocardial fibrosis (EMF), recently described by Dubost," Metras,? Moraes," and their co-workers, consists of endocardial resection with atrioventricular valve replacement. However, this disease differs from IHES even though the cardiac lesions are histologically indistinguishable. II IHES is a systemic disease of eosinophilia that can affect any tissue, with the most clinically significant lesions occurring in the cardiac and central nervous systems. 1-3 EMF appears to be limited to the ventricular endocardium, with secondary organ injury being related to ventricular failure.r'? IHES primarily affects men and is found worldwide, whereas EMF has little sexual predilection and is usually found in well-defined geographic regions. I. 9. II It is likely that the spectrum of endocardial response to injury is limited and the histologically identical fibrotic lesions of EMF and IHES are but the final result of an end organ response." In IHES this response is due to eosinophilia, whereas in EMF the cause has not yet been defined. The endocardial fibrosis of IHES is usually diffuse and may be either univentricular or biventricular, with the atrioventricular valves being affected in half of the patients."? The unusual feature of our patient was the very localized area of endocardial fibrosis involving the mitral valve and the rapid progression of left ventricular failure. The approach to our patient was similar to that of Bell," Weyman,' Fauci,' and their co-workers. A patient with IHES and worsening cardiac symptoms with a regurgitant or stenotic atrioventricular valve may be an excellent candidate for valve replacement or repair if the cardiomyopathy is not severe, provided that the extracardiac manifestations of the eosinophilic process, especially referable to the central nervous system, can be controlled medically. The encouraging reports from the NIH I -3 suggested that aggressive medical therapy may prevent progressive restrictive cardiomyopathy. More patients whose principal disability is the result of hemodynamic compromise from valvular insufficiency or stenosis could then benefit from valvular operations. Our patient had a relatively localized process that was amenable to resection en bloc with the valve. His favorable response to steroid therapy along with a most satisfactory operation has made us cautiously optimistic that he will enjoy a more favorable long-term result than might have been predicted earlier in his course.
REFERENCES
2
3
4
5
6
7
8
9
10
II
Fauci AS, Harley JB, Roberts WC, Ferrans VJ, Gralnick HR, Bjornson BH: The idiopathic hypereosinophilic syndrome. Clinical, pathophysiologic and therapeutic considerations. Ann Intern Moo 97:78-92, 1982 Parrillo JE, Fauci AS, Wolff SM: Therapy of the hypereosinophilic syndrome. Ann Intern Moo 89: 167-172, 1978. Parrillo JE, Borer JS, Henry WL, Wolff SM, Fauci AS: The cardiovascular manifestations of the hypereosinophilic syndrome. Prospective study of 26 patients, with review of the literature. Am J Moo 67:572-582, 1979 Chusid MJ, Dale DC, West BC, Wolff SM: The hypereosinophilic syndrome: Analysis of fourteen cases with review of the literature. Medicine 54:1-27, 1975 Roberts WC, Liegler DC, Carbone PP: Endomyocardial disease and eosinophilia. A clinical and pathologic spectrum. Am J Moo 46:28-42, 1969 Bell JA, Jenkins BS, Webb-Peploe MM: Clinical, haemodynamic, and angiographic findings in Loffler's eosinophilic endocarditis. Br Heart J 38:541-548, 1976 Weyman AE, Rankin R, King H: Loeffler's endocarditis presenting as mitral and tricuspid stenosis. Am J Cardiol 40:438-444, 1977 Dubost C, Prigent C, Gerbaux A, Maurice P, Passelecq J, Rulliere R, Carpentier A, Deloche A: Surgical treatment of constrictive fibrous endocarditis. J THORAC CARDlOVASC SURG 82:585-591,1981 Metras D, Coulibaly AO, Ouattara K, Chauvet J, Ekra A, Longechaud A, Bertrand E: Endomyocardial fibrosis. Early and late results of surgery in 20 patients. J THORAC CARDIOVASC SURG 83:52-64, 1982 Moraes CR, Buffolo E, Lima R, Victor E, Lira V, Escobar M, Rodrigues J, Saraiva L, Andrade JC: Surgical treatment of endomyocardial fibrosis. J THORAC CARDIOV ASC SURG 85:738-745,1983 Brockington IF, Olsen EGJ: Loffler's endocarditis and Davies' endomyocardial fibrosis. Am Heart J 85:308-322, 1973
Secondary left atrioventricular valve replacement in atrioventricular septal (AV canal) defect: A method to avoid left ventricular outflow tract obstruction Lynn B. McGrath, M.D., John W. Kirklin, M.D., Benigno Soto, M.D., and L. M. Bargeron, Jr., M.D., Birmingham, Ala. From the Departments of Surgery, Pediatrics, and Radiology, School of Medicine and the Medical Center, The University of Alabama in Birmingham, and the Alabama Congenital Heart Disease Diagnosis and Treatment Center, Birmingham, Ala. Address for reprints: John W. Kirklin, M.D., Department of Surgery, University Station, Birmingham, Ala. 35294.
Volume 89 Number 4
Brief communications 6 3 3
April. 1985
Patients with atrioventricular septal defects are morphologically predisposed to subaortic obstruction. Some individuals require secondary left atrioventricular valve replacement for severe incompetence persisting after repair, and they are especially susceptible to left ventricular outflow tract obstruction. A surgical technique is described for replacement of the atrioventricular valvewhich seems to avoid the complication of left ventricular outflow tract obstruction by the prosthesis.
Predisposition to left ventricular outflow tract (LVOT) obstruction is a well-known phenomenon in patients with atrioventricular septal (AV canal) defects,1,2 and rarely actual subaortic stenosis exists or develops." Patients with this anomaly who require left AV valve replacement because of persisting severe incompetenceafter repair are therefore at increased risk of LVOT obstruction, and important obstruction has developed in a few patients. A method designed to prevent this problem is described here. Operative technique. After the secondary median sternotomy incision is made, cardiopulmonary bypass is established with direct caval cannulation, ascending aortic cannulation, moderate systemic hypothermia at 25° C, and periods of low-flow perfusion as required to facilitate exposure. Myocardial preservation is achieved with multidose high-potassium cold cardioplegia. When the operation is done as a secondary procedure, the left
AV valve is exposed by a right-sided left atriotomy or transseptally through a right atriotomy. When the operation is done immediately after repair, the left AV valve is exposed by dividing the sutures between the pericardial patch and atrial septum. The left AV valve is examined carefully to determine if secondary repair is possible. If it is not, the leaflets are excised, with a fringe of leaflet tissue left along the base of the left inferior leaflet inferiorly and along the undersurface of the pericardial patch superiorly (Fig. 1). A crescent-shaped knitted Dacron cuff is prepared and attached to the superior aspect of the anulus with a continuous suture (Fig. I). It can be thought of as widening of the "mitral" aortic anulus. The valve prosthesis is sutured into place with interrupted sutures as shown in Fig. I. The Dacron cuff tilts the prosthesis upward into the left atrial chamber and thus out of the LVOT. Use of the cuff also avoids suturing in the area occupied by the AV node and His bundle. Patients. Five patients who had undergone repair of an AV septal defect, either that day or previously, were operated upon between January, 1983, and July 1,1984, because of continuing severe left AV valve incompetence (Table I). The technique of left AV valve replacement described was used. The ages of the patients ranged from 8 months to 19 years. Two were boys and three
Fig. I. Left atrioventricular (A V) valve replacement for incompetence late after repair of complete (or partial) AV canal defect, with an approach through the right side of the left atrium. A, The proposed incision into the left atrium is shown. The artist also has shown the right atrium open to aid in orientation of the subsequent drawings. B, The left atrium is opened from the right side, as is usual for mitral valve operations. The left AV valve is excised, with a fringe of leaflet tissue left anteriorly, along the undersurface of the pericardial patch, and inferiorly. The position of the left ventricular outflow tract is shown. Ao, Aorta. SVC, Superior vena cava.
The Journal of
6 3 4 Brief communications
Thoracic and Cardiovascular Surgery
Fig. 1. Cont'd. C. A crescent-shaped Dacron patch is fashioned and attached to the area of annular attachment of the now excised left superior leaflet, thereby effectively lengthening the "mitral"-aortic anulus so that the valve replacement device will be away from the left ventricular outflow tract. D, A low-profile valve replacement device is inserted, sewn to the free edge of Dacron patch superiorly, to the anulus posteriorly, and to leaflet remnants inferiorly and anteriorly. Using leaflet remnants in this region avoids damage to the AV node and His bundle. E, Thereby, the valve is positioned up out of the left ventricular outflow tract and into the left atrium.
Table I. Patients receiving left atrioventricular (AY) valve replacement by the technique described
Patient
1 2 3 4 5
Type of AV septal defect
Date of repair of AV septal defect
Date of valve replacement
Complete Partial Complete Complete Partial
4/1977 2/1975 11/1983 12/1981 2/1984
3/1983 7/1983 11/1983 1/1984 2/1984
Age at valve replacement
NYHA functional class at follow-up
2\12 yr yr mo yr yr
II 8 4 19
Rhythm at follow-up
Prosthesis
NSR NSR NSR NSR NSR
25 mm B-S 21 mm SJM 19 mm SJM 23 mm B-S 29 mm B-S
Legend: NYHA, New York Heart Association. NSR, Normal sinus rhythm. B-S, Bjork-Shiley,SJM, SI. Jude Medical.
girls. The patients were placed on a regimen of warfarin on postoperative day 2. Follow-up. Each of the five patients and/or his physician was contacted by telephone on Aug. 1, 1984. Follow-up ranged from 35 to 348 days, with a mean of 152 days. Results. All patients have survived, and all are presently in New York Heart Association Functional Class I with normal sinus rhythm. There have been no episodes of thromboembolism, prosthetic valve endocarditis, or periprosthetic leakage. There have been no further reoperations.
Postoperative two-dimensional echocardiograms were performed on all patients, and no evidence for subaortic obstruction was found. Catheterization, performed on postoperative day 6 in one patient, showed normal prosthetic valve function and a mild LVOT gradient (Fig. 2). Discussion. A hallmark of an AV canal defect is a disproportion in length between the lengthened outlet ventricular septum and the shortened inlet septum. I There is a spectrum of associated malformations, one of which is the lengthening of the LVOT because of a rightward and anterior deviation of the aorta, and a
Volume 89 Number 4
Brief communications
April, 1985
Fig. 2. Four-chamber view of the left ventricular angiogram in a patient with atrioventricular septal defect (complete AV canal defect) who required left AV valve replacement. The technique described was used. The Bjork-Shiley prosthesis does not project into the congenitally narrow left ventricular outflow tract. Postoperatively, systolic pressure in the left ventricle was 125 mm Hg and in the aorta, 115 mrn Hg.
narrowing of the LVOT because of the A V valve attachments to the deficient interventricular septum (Fig. 3). Related to this malformation is the fact that narrowing is an intrinsic characteristic of the L VOT of patients with AV canal defects.' Indeed, an anterior position of the LVOT, with rightward deviation and increased outflow tract length, was present in 56 (49%; 70% confidence limits 44% to 54%) of 114 cases from the autopsy series examined by Piccoli and colleagues.' In rare cases, severe subaortic stenosis may coexist with an AV septal defect.' Also, the repair of an AV septal defect is known to create an actual stenosis from potential subaortic stenosis in some patients.v' For these same morphologic reasons, insertion of a prosthetic valve into the left A V valve orifice in patients with AV canal defects may convert potential LVOT obstruction into actual obstruction, and valve replacement also carries an increased risk of complete heart block.
635
Fig. 3. Anteroposterior view of left ventricular angiogram in diastole in another patient with atrioventricular septal defect (complete AV canal defect). The arrows indicate the elongated left ventricular outflow tract, due to absence of the AV septum, anterior migration of the aortic valve, shortening of the inlet septum, and lengthening of the left ventricular outflow tract. A prosthesis projecting into the outflow tract could produce important obstruction. The technique described here permits the prosthesis to sit up in the left atrial chamber and seems to avoid LVOT obstruction. The technique also allows insertion of a prosthesis with a larger diameter than that of the native valve orifice and seems to minimize the risk of complete heart block.
2
3 4
5
REFERENCES Piccoli GP, GerIis LM, Wilkinson JL, Lozsardi K, Macartney FJ, Anderson RH: Morphology and classification of atrioventricular defects. Br Heart J 42:621-632, 1979 Piccoli GP, Ho SY, Wilkinson JL, Macartney FJ, GerIis LM, Anderson RH: Left-sided obstructive lesions in atrioventricular septal defects. J THORAC CARDIOVASC SURG 83:453-460, 1982 Sellers RD, Lillehei CW, Edwards JE: Subaortic stenosis caused by anomalies of the atrioventricular valves. J THoRAc CARDIOVASC SURG 48:289-302, 1964 Ben-Shachar G, Moller JH, Castaneda-Zuniga W, Edwards JE: Signs of membranous subaortic stenosis appearing after correction of persistent common atrioventricular canal. Am J Cardiol 48:340-344, 1981 Lappen RS, Muster AJ, Idriss FS, Riggs TW, Ilbawi M, Paul MH, Bharati S, Lev M: Masked subaortic stenosis in ostium primum atrial septal defect. Recognition and treatment. Am J Cardiol 52:336-340, 1983
6 3 2 Brief communications
Surgery
of these patients have done well. The third patient died of prosthetic valve endocarditis. The infrequency of operative treatment no doubt has reflected the generalized nature of the endocardial fibrosis in most patients. Surgical intervention for diffuse endomyocardial fibrosis (EMF), recently described by Dubost," Metras,? Moraes," and their co-workers, consists of endocardial resection with atrioventricular valve replacement. However, this disease differs from IHES even though the cardiac lesions are histologically indistinguishable. II IHES is a systemic disease of eosinophilia that can affect any tissue, with the most clinically significant lesions occurring in the cardiac and central nervous systems. 1-3 EMF appears to be limited to the ventricular endocardium, with secondary organ injury being related to ventricular failure.r'? IHES primarily affects men and is found worldwide, whereas EMF has little sexual predilection and is usually found in well-defined geographic regions. I. 9. II It is likely that the spectrum of endocardial response to injury is limited and the histologically identical fibrotic lesions of EMF and IHES are but the final result of an end organ response." In IHES this response is due to eosinophilia, whereas in EMF the cause has not yet been defined. The endocardial fibrosis of IHES is usually diffuse and may be either univentricular or biventricular, with the atrioventricular valves being affected in half of the patients."? The unusual feature of our patient was the very localized area of endocardial fibrosis involving the mitral valve and the rapid progression of left ventricular failure. The approach to our patient was similar to that of Bell," Weyman,' Fauci,' and their co-workers. A patient with IHES and worsening cardiac symptoms with a regurgitant or stenotic atrioventricular valve may be an excellent candidate for valve replacement or repair if the cardiomyopathy is not severe, provided that the extracardiac manifestations of the eosinophilic process, especially referable to the central nervous system, can be controlled medically. The encouraging reports from the NIH I -3 suggested that aggressive medical therapy may prevent progressive restrictive cardiomyopathy. More patients whose principal disability is the result of hemodynamic compromise from valvular insufficiency or stenosis could then benefit from valvular operations. Our patient had a relatively localized process that was amenable to resection en bloc with the valve. His favorable response to steroid therapy along with a most satisfactory operation has made us cautiously optimistic that he will enjoy a more favorable long-term result than might have been predicted earlier in his course.
REFERENCES
2
3
4
5
6
7
8
9
10
II
Fauci AS, Harley JB, Roberts WC, Ferrans VJ, Gralnick HR, Bjornson BH: The idiopathic hypereosinophilic syndrome. Clinical, pathophysiologic and therapeutic considerations. Ann Intern Moo 97:78-92, 1982 Parrillo JE, Fauci AS, Wolff SM: Therapy of the hypereosinophilic syndrome. Ann Intern Moo 89: 167-172, 1978. Parrillo JE, Borer JS, Henry WL, Wolff SM, Fauci AS: The cardiovascular manifestations of the hypereosinophilic syndrome. Prospective study of 26 patients, with review of the literature. Am J Moo 67:572-582, 1979 Chusid MJ, Dale DC, West BC, Wolff SM: The hypereosinophilic syndrome: Analysis of fourteen cases with review of the literature. Medicine 54:1-27, 1975 Roberts WC, Liegler DC, Carbone PP: Endomyocardial disease and eosinophilia. A clinical and pathologic spectrum. Am J Moo 46:28-42, 1969 Bell JA, Jenkins BS, Webb-Peploe MM: Clinical, haemodynamic, and angiographic findings in Loffler's eosinophilic endocarditis. Br Heart J 38:541-548, 1976 Weyman AE, Rankin R, King H: Loeffler's endocarditis presenting as mitral and tricuspid stenosis. Am J Cardiol 40:438-444, 1977 Dubost C, Prigent C, Gerbaux A, Maurice P, Passelecq J, Rulliere R, Carpentier A, Deloche A: Surgical treatment of constrictive fibrous endocarditis. J THORAC CARDlOVASC SURG 82:585-591,1981 Metras D, Coulibaly AO, Ouattara K, Chauvet J, Ekra A, Longechaud A, Bertrand E: Endomyocardial fibrosis. Early and late results of surgery in 20 patients. J THORAC CARDIOVASC SURG 83:52-64, 1982 Moraes CR, Buffolo E, Lima R, Victor E, Lira V, Escobar M, Rodrigues J, Saraiva L, Andrade JC: Surgical treatment of endomyocardial fibrosis. J THORAC CARDIOV ASC SURG 85:738-745,1983 Brockington IF, Olsen EGJ: Loffler's endocarditis and Davies' endomyocardial fibrosis. Am Heart J 85:308-322, 1973
Secondary left atrioventricular valve replacement in atrioventricular septal (AV canal) defect: A method to avoid left ventricular outflow tract obstruction Lynn B. McGrath, M.D., John W. Kirklin, M.D., Benigno Soto, M.D., and L. M. Bargeron, Jr., M.D., Birmingham, Ala. From the Departments of Surgery, Pediatrics, and Radiology, School of Medicine and the Medical Center, The University of Alabama in Birmingham, and the Alabama Congenital Heart Disease Diagnosis and Treatment Center, Birmingham, Ala. Address for reprints: John W. Kirklin, M.D., Department of Surgery, University Station, Birmingham, Ala. 35294.
Volume 89 Number 4
Brief communications 6 3 3
April. 1985
Patients with atrioventricular septal defects are morphologically predisposed to subaortic obstruction. Some individuals require secondary left atrioventricular valve replacement for severe incompetence persisting after repair, and they are especially susceptible to left ventricular outflow tract obstruction. A surgical technique is described for replacement of the atrioventricular valvewhich seems to avoid the complication of left ventricular outflow tract obstruction by the prosthesis.
Predisposition to left ventricular outflow tract (LVOT) obstruction is a well-known phenomenon in patients with atrioventricular septal (AV canal) defects,1,2 and rarely actual subaortic stenosis exists or develops." Patients with this anomaly who require left AV valve replacement because of persisting severe incompetenceafter repair are therefore at increased risk of LVOT obstruction, and important obstruction has developed in a few patients. A method designed to prevent this problem is described here. Operative technique. After the secondary median sternotomy incision is made, cardiopulmonary bypass is established with direct caval cannulation, ascending aortic cannulation, moderate systemic hypothermia at 25° C, and periods of low-flow perfusion as required to facilitate exposure. Myocardial preservation is achieved with multidose high-potassium cold cardioplegia. When the operation is done as a secondary procedure, the left
AV valve is exposed by a right-sided left atriotomy or transseptally through a right atriotomy. When the operation is done immediately after repair, the left AV valve is exposed by dividing the sutures between the pericardial patch and atrial septum. The left AV valve is examined carefully to determine if secondary repair is possible. If it is not, the leaflets are excised, with a fringe of leaflet tissue left along the base of the left inferior leaflet inferiorly and along the undersurface of the pericardial patch superiorly (Fig. 1). A crescent-shaped knitted Dacron cuff is prepared and attached to the superior aspect of the anulus with a continuous suture (Fig. I). It can be thought of as widening of the "mitral" aortic anulus. The valve prosthesis is sutured into place with interrupted sutures as shown in Fig. I. The Dacron cuff tilts the prosthesis upward into the left atrial chamber and thus out of the LVOT. Use of the cuff also avoids suturing in the area occupied by the AV node and His bundle. Patients. Five patients who had undergone repair of an AV septal defect, either that day or previously, were operated upon between January, 1983, and July 1,1984, because of continuing severe left AV valve incompetence (Table I). The technique of left AV valve replacement described was used. The ages of the patients ranged from 8 months to 19 years. Two were boys and three
Fig. I. Left atrioventricular (A V) valve replacement for incompetence late after repair of complete (or partial) AV canal defect, with an approach through the right side of the left atrium. A, The proposed incision into the left atrium is shown. The artist also has shown the right atrium open to aid in orientation of the subsequent drawings. B, The left atrium is opened from the right side, as is usual for mitral valve operations. The left AV valve is excised, with a fringe of leaflet tissue left anteriorly, along the undersurface of the pericardial patch, and inferiorly. The position of the left ventricular outflow tract is shown. Ao, Aorta. SVC, Superior vena cava.
The Journal of
6 3 4 Brief communications
Thoracic and Cardiovascular Surgery
Fig. 1. Cont'd. C. A crescent-shaped Dacron patch is fashioned and attached to the area of annular attachment of the now excised left superior leaflet, thereby effectively lengthening the "mitral"-aortic anulus so that the valve replacement device will be away from the left ventricular outflow tract. D, A low-profile valve replacement device is inserted, sewn to the free edge of Dacron patch superiorly, to the anulus posteriorly, and to leaflet remnants inferiorly and anteriorly. Using leaflet remnants in this region avoids damage to the AV node and His bundle. E, Thereby, the valve is positioned up out of the left ventricular outflow tract and into the left atrium.
Table I. Patients receiving left atrioventricular (AY) valve replacement by the technique described
Patient
1 2 3 4 5
Type of AV septal defect
Date of repair of AV septal defect
Date of valve replacement
Complete Partial Complete Complete Partial
4/1977 2/1975 11/1983 12/1981 2/1984
3/1983 7/1983 11/1983 1/1984 2/1984
Age at valve replacement
NYHA functional class at follow-up
2\12 yr yr mo yr yr
II 8 4 19
Rhythm at follow-up
Prosthesis
NSR NSR NSR NSR NSR
25 mm B-S 21 mm SJM 19 mm SJM 23 mm B-S 29 mm B-S
Legend: NYHA, New York Heart Association. NSR, Normal sinus rhythm. B-S, Bjork-Shiley,SJM, SI. Jude Medical.
girls. The patients were placed on a regimen of warfarin on postoperative day 2. Follow-up. Each of the five patients and/or his physician was contacted by telephone on Aug. 1, 1984. Follow-up ranged from 35 to 348 days, with a mean of 152 days. Results. All patients have survived, and all are presently in New York Heart Association Functional Class I with normal sinus rhythm. There have been no episodes of thromboembolism, prosthetic valve endocarditis, or periprosthetic leakage. There have been no further reoperations.
Postoperative two-dimensional echocardiograms were performed on all patients, and no evidence for subaortic obstruction was found. Catheterization, performed on postoperative day 6 in one patient, showed normal prosthetic valve function and a mild LVOT gradient (Fig. 2). Discussion. A hallmark of an AV canal defect is a disproportion in length between the lengthened outlet ventricular septum and the shortened inlet septum. I There is a spectrum of associated malformations, one of which is the lengthening of the LVOT because of a rightward and anterior deviation of the aorta, and a
Volume 89 Number 4
Brief communications
April, 1985
Fig. 2. Four-chamber view of the left ventricular angiogram in a patient with atrioventricular septal defect (complete AV canal defect) who required left AV valve replacement. The technique described was used. The Bjork-Shiley prosthesis does not project into the congenitally narrow left ventricular outflow tract. Postoperatively, systolic pressure in the left ventricle was 125 mm Hg and in the aorta, 115 mrn Hg.
narrowing of the LVOT because of the A V valve attachments to the deficient interventricular septum (Fig. 3). Related to this malformation is the fact that narrowing is an intrinsic characteristic of the L VOT of patients with AV canal defects.' Indeed, an anterior position of the LVOT, with rightward deviation and increased outflow tract length, was present in 56 (49%; 70% confidence limits 44% to 54%) of 114 cases from the autopsy series examined by Piccoli and colleagues.' In rare cases, severe subaortic stenosis may coexist with an AV septal defect.' Also, the repair of an AV septal defect is known to create an actual stenosis from potential subaortic stenosis in some patients.v' For these same morphologic reasons, insertion of a prosthetic valve into the left A V valve orifice in patients with AV canal defects may convert potential LVOT obstruction into actual obstruction, and valve replacement also carries an increased risk of complete heart block.
635
Fig. 3. Anteroposterior view of left ventricular angiogram in diastole in another patient with atrioventricular septal defect (complete AV canal defect). The arrows indicate the elongated left ventricular outflow tract, due to absence of the AV septum, anterior migration of the aortic valve, shortening of the inlet septum, and lengthening of the left ventricular outflow tract. A prosthesis projecting into the outflow tract could produce important obstruction. The technique described here permits the prosthesis to sit up in the left atrial chamber and seems to avoid LVOT obstruction. The technique also allows insertion of a prosthesis with a larger diameter than that of the native valve orifice and seems to minimize the risk of complete heart block.
2
3 4
5
REFERENCES Piccoli GP, GerIis LM, Wilkinson JL, Lozsardi K, Macartney FJ, Anderson RH: Morphology and classification of atrioventricular defects. Br Heart J 42:621-632, 1979 Piccoli GP, Ho SY, Wilkinson JL, Macartney FJ, GerIis LM, Anderson RH: Left-sided obstructive lesions in atrioventricular septal defects. J THORAC CARDIOVASC SURG 83:453-460, 1982 Sellers RD, Lillehei CW, Edwards JE: Subaortic stenosis caused by anomalies of the atrioventricular valves. J THoRAc CARDIOVASC SURG 48:289-302, 1964 Ben-Shachar G, Moller JH, Castaneda-Zuniga W, Edwards JE: Signs of membranous subaortic stenosis appearing after correction of persistent common atrioventricular canal. Am J Cardiol 48:340-344, 1981 Lappen RS, Muster AJ, Idriss FS, Riggs TW, Ilbawi M, Paul MH, Bharati S, Lev M: Masked subaortic stenosis in ostium primum atrial septal defect. Recognition and treatment. Am J Cardiol 52:336-340, 1983