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Extended aortic root replacement with cryopreserved allografts: Do they hold up?
Extended Aortic Root Replacement With Cryopreserved Allografts: Do They Hold Up? David R. Clarke, MD Division of Cardiothoracic Surgery, The Children's Hospital, University of Colorado Health Sciences Center, Denver, Colorado
The extended aortic root replacement technique is used for the surgical repair of left ventricular outflow tract obstruction complicated by concurrent hypoplastic aortic annulus, multiple levels of obstruction, or aortic insufficiency. Extended aortic root replacement incorporates the concepts of aortic root replacement and aortoventriculoplasty to create a comparatively simple procedure. Unique features of the technique include the implantation of an allograft, which makes the need for anticoagulation obsolete, and use of the donor mitral leaflet to enlarge the outflow tract. Since 1985, 32 patients in
M
urray [l]first implanted the aortic valve allograft in a clinical setting in 1956. More than 30 years later, advances in methods of preservation and in surgical techniques have propelled allografts to the forefront as tools for the repair of complex congenital cardiac anomalies. Compared with bioprostheses and mechanical valves, allografts are easier to insert with minimal bleeding, show minor gradients, and exhibit a decreased incidence of thromboembolism and hemolysis [2]. Aortic valve allografts used for extended aortic root replacement (EARR) offer an effective option in the surgical management of left ventricular (LV) outflow tract obstruction complicated by the presence of hypoplastic annulus, aortic insufficiency, or multiple levels of obstruction.
Material and Methods Thirty-two patients underwent 33 EARR procedures from September 1985 through September 1990 at The Children's Hospital and the University of Colorado Health Sciences Center in Denver. There were 20 male (63%)and 12 female patients (38%).At the time of operation, age ranged from 11 days to 29 years (mean age, 10.1 years). Indication for operation was complex aortic stenosis in 13 patients (41%),recurrent subvalvar aortic stenosis in 13 (41%), hypoplastic aortic annulus in 4 (13%), and aortic valve insufficiency with stenosis in 2 (6%). Preoperative transvalvar aortic gradients at cardiac catheterization ranged from 22 to 100 mm Hg with a mean gradient of 68 mm Hg. Aortic valve insufficiency was present in 22 patients (69%). Presented in part at the Current Controversies and Techniques in Congenital Heart Surgery Meeting, Baltimore, MD, Sep %9, 1989. Address reprint requests to Dr Clarke, The Children's Hospital, Cardiothoracic Surgery, 8200, 1056 E 19th Ave, Denver, CO 80218.
0 1991 by The Society of
Thoracic Surgeons
Denver have undergone placement of a cryopresewed aortic valve allograft as part of extended aortic root replacement. There were four hospital deaths (13%), and 1child underwent cardiac transplantation 30 hours after operation. In 6 months to 4.8 years of follow-up, a 14-year-old boy with familial hyperlipidemia required coronary artery bypass grafting, and 3 children experienced allograft calcification with progressive insufficiency, which prompted allograft replacement. The other 23 patients are clinically well. (Ann Thorac Surg 1991;52:669-75)
With the exception of 1 patient with Phemolytic streptococci endocarditis, all patients had undergone at least one prior cardiovascular operation. There were 16 previous aortic subvalvar membrane resections or myectomies, 15 aortic valvotomies, and 10 interrupted aortic arch or coarctation repairs. Two patients had required atrial septal defect repair. There were single instances of prior aortic valve replacement, placement of a ventricular apexdescending aorta conduit, atrial and ventricular septa1 defect repair, and creation of a portacaval shunt. The EARR technique emerged when the concepts of aortic root replacement of Somerville and Ross [3] were combined with those of aortoventriculoplasty as described independently by Konno and associates [4] and Rastan and Koncz [5]. Extended aortic root replacement is unique in that a cryopreserved valve allograft is used rather than a mechanical or bioprosthetic valve. The anterior mitral leaflet attached to the aortic valve allograft provides a natural patch with which the subvalvar area in the interventricular septum can be enlarged [6]. In anticipation of EARR, patient weight is used to determine suitable conduit size (Fig 1). During preparations for cardiopulmonary bypass, the allograft is extracted from the liquid nitrogen refrigerator. Still enveloped in three pouches, the valved conduit is thawed in a nonsterile water bath at 37" to 42°C for no longer than 16 minutes. The two outer pouches are removed, and the sterile inner one is passed to the scrub nurse. To dilute the dimethyl sulfoxide cryoprotectant, the graft is rinsed successively in three basins containing increasing concentrations of Dulbecco's medium with a final rinse in lactated Ringer's solution. The allograft is ready for implantation after acquisition of a tissue sample for microbiological culture. The chest is entered through a median sternotomy. After cannulation of the ascending aorta and superior and 0003-4975/91/$3.50
670
CONGENITAL HEART CLARKE EXTENDED AORTIC ROOT REPLACEMENT
Ann Thorac Surg 1991;52:669-75
Fig 1 . Patient weight is used to determine appropriate range of allograft sizes suitable for implantation.
0
4
8
12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 Patient Weight (Kg)
inferior venae cavae, total bypass is initiated. Body temperature is reduced to 20°C. Blood cardioplegia is infused to preserve the myocardium, either anterograde or retrograde through the coronary sinus when there is aortic regurgitation. The incision that begins an EARR is similar to that performed in aortoventriculoplasty. A vertical ascending aortic incision meets an oblique one that traverses the right ventricular outflow tract. They intersect at the aortic annulus between the right and left coronary ostia. From that point, the incision crosses the annulus and divides the interventricular septum. The ascending aorta is transected with subsequent excision of coronary ostial buttons (Fig 2). Native aortic valve leaflets are excised from the annulus, and excess muscle is trimmed from the thawed allograft. The proximal anastomosis commences as allograft and recipient annuli are approximated posteriorly. Their orientation is crucial. The donor right coronary stump is aligned with the recipient left coronary button. Suture lines are continued right and left to the interventricular septum (Fig 3). The donor mitral valve anterior leaflet is modified to allow repair of the septal incision and outflow tract enlargement (Fig 4). The suture line to the right ventricular edge of the septal incision is reinforced with buttressed sutures. Distally, the allograft conduit is severed to provide the exact length necessary to complete its connection to the ascending aorta. The visible valve leaflets must be protected while an aortic punch creates 5- or 6-mm holes in the donor aortic root. Holes are placed in proximity to the coronary ostial buttons to facilitate suturing. To eliminate a potential bleeding source behind the aorta, the donor right coronary stump can be resected to serve as an implantation site for the left coronary button. The distal anastomosis is initiated posteriorly from inside the lumen and progresses to the exterior to complete lateral and anterior connections. After a final warm dose of blood cardioplegia is administered anterograde, the aortic crossclamp is released
Fig 2 An incision similar to that performed in aortoventriculoplasty crosses the aortic annulus and divides the interventricular septum The ascending aorta is transected, and coronary buttons are excised (Reprinted from Clarke DR Extended aortic root replacement for treatment of left ventricular outflow tract obstruction J Cardiac Surg 1987, 2lSuppll 121-8, by permission of Futura Publishing Company, Inc )
CONGENITAL HEART CLARKE EXTENDED AORTIC ROOT REPLACEMENT
Ann Thorac Surg 1991;52669-75
671
A triangular patch cut from the remaining distal allograft aorta is used to repair the right ventricular outflow tract. The base of the patch is sutured to the donor aortic root annulus; tailoring of the corners is done with special care to avoid bleeding (Fig 5). The right ventricular suture line is then completed with the heart beating as rewarming progresses. Temporary pacemaker wires are placed for postoperative management. After the patient is weaned from cardiopulmonary bypass, the operation is completed in standard manner.
Results Aortic valve allografts with an internal diameter of 11 to 25 mm (mean diameter, 19 mm) were implanted. Children weighing as little as 15 kg were able to receive adult-sized allografts. Three patients (9%)died intraoperatively. A 24-year-old man had undergone three previous cardiac surgical procedures. At 4 years of age, he required aortic valvotomy. Eight years later, the aortic valve was replaced, and at age
.-
Fig 4. The anterior leaflet of the donor mitral valve is used to repair the septa1 incision and to enlarge the outflow tract. This portion of the suture line is usually reinforced with pledgeted sutures. (Reprinted from Clarke DR. Extended aortic root replacement for treatment of left ventricular outflow tract obstruction. Cardiac Surg 1987;2[Suppll: 121-8; by permission of Futura Publishing Company, Znc.)
. .. ?. Fig 3 . Allograft and recipient annuli are approximated posteriorly. Suture lines continue right and left to the interventricular septum. (Reprinted from Clarke DR. Extended aortic root replacement for treatment of left ventricular outflow tract obstruction. ] Cardiac Surg 1987;21Suppll:121-8; by permission of Futura Publishing Company, rnc.)
15 years, a ventricular apex-descending aorta conduit was placed. He was seen for his fourth cardiac procedure with severe aortic stenosis and apicoaortic conduit valve insufficiency. On completion of EARR, there was excessive blood loss during takedown of the apicoaortic conduit, and this caused hypotension with subsequent LV failure and death. The second intraoperative death occurred in a 3-yearold girl with a transvalvar aortic gradient of 80 mm Hg, moderate insufficiency, and progressive LV hypertrophy. She had undergone aortic valvotomy at the age of 20 months. Problems were encountered with reimplantation of the left coronary artery, and the child could not be weaned from cardiopulmonary bypass secondary to ischemic contracture. An 11-day-old female neonate had undergone aortic valvotomy on the first day of life. Severe aortic stenosis with LV dysfunction persisted. At the time of EARR, severe (3 to 4 mm thick) endocardia1 fibroelastosis of the left ventricle was discovered. The LV dysfunction caused her death. One hospital death occurred in a 9-year-old boy. He had had prior aortic coarctation repair as well as an LV
672
CONGENITAL HEART CLARKE EXTENDED AORTIC ROOT REPLACEMENT
f
'
Fig 5. Buttons of coronary ostia have been reimplanted, and the distal anastomosis is complete. A triangular patch of distal allograft is used to repair the right ventricular outflow tract. (Reprinted from Clarke DR. Extended aortic root replacement for treatment of left ventricular outflow tract obstruction. J Cardiac Surg 2987;2iSuppll:2228; by permission of Futura Publishing Company, Inc.)
outflow tract myectomy. Reoperation was performed when recurrent subvalvar aortic stenosis in addition to aortic and mitral valve stenosis and pulmonary hypertension developed. At the time of EARR, mitral subvalvar chordal fusion was fenestrated. The postoperative course was marked by hemodynamic deterioration with intermittent stabilization. He died of biventricular failure on the seventh postoperative day. Cardiac transplantation was ultimately done in a 5-yearold child with multilevel aortic stenosis and congenital mitral stenosis. Prior cardiac operations included repair of coarctation of the aorta at 4 days of age and aortic subvalvar membrane resection at 8 months. Mitral valve replacement was performed concurrently with EARR. Intraoperatively, LV failure necessitated the use of an LV assist device. With no improvement in LV function and deteriorating right ventricular function, the child underwent cardiac transplantation 30 hours after the allograft procedure and is alive and well at 6 months' follow-up.
Ann Thorac Surg 1991;52:669-75
Of the other patients, 9 (33%) experienced a benign hospitalization. Although the list of postoperative complications is extensive, the majority were temporary and had resolved by discharge (Table 1). Noteworthy was the development of Serratia marcescens mediastinitis and bacteremia in 1 child, which required debridement and irrigation. A 6-week course of antibiotics was administered. Allograft function was unaffected. The surviving EARR recipients have been followed up clinically for 6 months to 4.8 years (mean follow-up, 2.5 years). Coronary artery bypass grafting was necessary in a 14-year-old boy with familial hyperlipidemia. Six months after allograft placement secondary to a hypoplastic aortic annulus, the child was readmitted with angina pectoris. On cardiac catheterization, a narrowed distal allograft-native aorta anastomosis was evidenced as well as 80% obstruction of the left main coronary artery. Surgical inspection revealed a normal allograft valve with lipid deposits on the intima. The coronary artery lesion was attributed to progression of the hyperlipidemia, as the stenosis was 2 cm from the ostia. The allograft was not replaced. Three infants aged 3, 7, and 12 months experienced allograft calcification, stenosis, and progressive insufficiency, which eventually required reoperation. One child underwent redo EARR 8 months after the initial procedure. Intraoperative findings were compatible with rejection. Calcification involved the allograft conduit wall and right ventricular outflow tract patch; the aortic valve leaflets were fibrotic and retracted. The donor mitral leaflet in the septum was unaffected. Reoperative techniques were identical to those of the first EARR including replacement of the calcified right ventricular outflow tract patch to allow implantation of a larger conduit. Administration of cyclosporine was initiated concurrent with the implantation of a second allograft. Twenty-one months later, the child is normally active and asymptomatic.
Table 1 . Early Postoperative Complications of Extended Aortic Root Replacement Complication Transient heart block Bleeding leading to reoperation Postpericardiotomy syndrome Arrhythmias Pleural effusion Serratia marcescens mediastinitis Superficial wound infection Right phrenic nerve palsy Incisional ventral hernia Pericardial effusion Dialysis and ventilatory support Mucous secretions leading to bronchoscopy Atelectasis No complications
No. of Patients
4 3 3 3 2
1 1 1 1 1 1 1 1
9
CONGENITAL HEART CLARKE EXTENDED AORTIC ROOT REPLACEMENT
Ann Thorac Surg 1991:52:669-75
Table 2 . Most Recent Echocardiographic Evaluation After Extended Aortic Root Replacement Variable Left ventricular function Good Depressed Aortic stenosis None Mild Moderate Aortic insufficiency None Mild Moderate
No. of Patients 21 2 10 12 1 6 15 2
Of the 2 other patients who required allograft replacement, 1 infant received a mechanical aortic valve prosthesis through an aortoventriculoplasty technique 37 months after EARR. The other underwent a pulmonary autograft procedure [7, 81 39 months after allograft insertion. In each case, the calcified right ventricular outflow tract patch was replaced. Twenty-three survivors continue to lead clinically asymptomatic lives. Most recent echocardiographic evaluations at 6 months to 3.9 years (mean duration, 1.9 years) after EARR reveal mild aortic stenosis or insufficiency or both to be common. Left ventricular function is good in 21 (91%) of these patients (Table 2).
Comment Cryopreserved aortic valve allografts have enhanced the surgeon’s ability to correct extremely complex congenital cardiac anomalies. At times, they are the only available surgical option. The EARR technique is straightforward, prolonged or severe early postoperative complications are not excessive, and permanent complete heart block has not occurred. Of primary concern are the early allograft failures. Seven children less than 3 years old had EARR with one hospital death. Three of the other 6 children have ultimately required allograft replacement. This trend will be monitored intensively. In young patients, immunosup-
673
pressive therapy with low-dose cyclosporine or use of the pulmonary autograft procedure [8] are alternatives worthy of consideration. After nearly 5 years of follow-up, it is impossible to adequately answer the question posed by the title of this article. The long-term fate of allografts used in EARR procedures remains undetermined. Improved techniques of cryopreservation provide superior tissue viability, which may produce increased allograft durability [9]. Intermediate follow-up of aortic allograft valved conduits in the LV outflow tract is generally favorable. This observation in conjunction with the immediate advantages such as their relative ease of insertion, their versatility and resistance to infection, the avoidance of anticoagulation in the pediatric population, and the ability to implant adult sizes in children certainly justifies their continued use for LV outflow tract reconstruction, particularly in the older child.
References 1. Murray G. Homologous aortic valve segment transplants as surgical treatment for aortic and mitral insufficiency. Angiology 1956;7:466-71. 2. Matsuki 0, Robles A, Gibbs S, Bodnar E, Ross DN. Long-term performance of 555 aortic homografts in the aortic position. Ann Thorac Surg 1988;46:187-91. 3. Somerville J, Ross D. Homograft replacement of aortic root with reimplantation of coronary arteries. Results after one to five years. Br Heart J 1982;47473-82. 4. Konno S, Imai J, Iida Y, et al. A new method for prosthetic valve replacement in congenital aortic stenosis associated with hypoplasia of the aortic valve ring. J Thorac Cardiovasc Surg 1975;70:909-17. 5. Rastan H, Koncz J. Aortoventriculoplasty. A new technique for the treatment of left ventricular outflow tract obstruction. J Thorac Cardiovasc Surg 1976;71:920-7. 6. Clarke DR. Extended aortic root replacement in 12 patients with complex left ventricular outflow tract obstruction. In: Yankah AC, Hetzer R, Miller DC, et al, eds. Cardiac valve allografts 1962-1987: current concepts on the use of aortic and pulmonary allografts for heart valve substitutes. New York: Springer-Verlag, 1988:15745. 7. Stelzer P, Jones DJ, Elkins RC. Aortic root replacement with pulmonary autograft. Circulation 1989;8O(Suppl3):209-13. 8. Matsuki 0, Okita Y, Almeida RS, et al. Two decades’ experience with aortic valve replacement with pulmonary autograft. J Thorac Cardiovasc Surg 1988;95:70511. 9. O‘Brien MF, Stafford G, Gardner M, et al. The viable cryopreserved allograft aortic valve. J Cardiac Surg 1987;1:153-67.
COMMENTARY: Homograft Aortic Root Replacement I read with interest Dr Clarke’s paper on extended aortic root replacement and have heard him talk on the subject on a number of occasions. We are in complete agreement on the advantages of using an adult-sized homograft root that the child will grow into rather than a small mechan-
ical valve that the child will outgrow and therefore be seen later with an obstructive prosthesis. The homograft is the only biological valve (apart from the pulmonary autograft) applicable to children, and because it is inserted as a complete functional entity and is not distorted by sur-
The extended aortic root replacement technique is used for the surgical repair of left ventricular outflow tract obstruction complicated by concurrent hypoplastic aortic annulus, multiple levels of obstruction, or aortic insufficiency. Extended aortic root replacement incorporates the concepts of aortic root replacement and aortoventriculoplasty to create a comparatively simple procedure. Unique features of the technique include the implantation of an allograft, which makes the need for anticoagulation obsolete, and use of the donor mitral leaflet to enlarge the outflow tract. Since 1985, 32 patients in
M
urray [l]first implanted the aortic valve allograft in a clinical setting in 1956. More than 30 years later, advances in methods of preservation and in surgical techniques have propelled allografts to the forefront as tools for the repair of complex congenital cardiac anomalies. Compared with bioprostheses and mechanical valves, allografts are easier to insert with minimal bleeding, show minor gradients, and exhibit a decreased incidence of thromboembolism and hemolysis [2]. Aortic valve allografts used for extended aortic root replacement (EARR) offer an effective option in the surgical management of left ventricular (LV) outflow tract obstruction complicated by the presence of hypoplastic annulus, aortic insufficiency, or multiple levels of obstruction.
Material and Methods Thirty-two patients underwent 33 EARR procedures from September 1985 through September 1990 at The Children's Hospital and the University of Colorado Health Sciences Center in Denver. There were 20 male (63%)and 12 female patients (38%).At the time of operation, age ranged from 11 days to 29 years (mean age, 10.1 years). Indication for operation was complex aortic stenosis in 13 patients (41%),recurrent subvalvar aortic stenosis in 13 (41%), hypoplastic aortic annulus in 4 (13%), and aortic valve insufficiency with stenosis in 2 (6%). Preoperative transvalvar aortic gradients at cardiac catheterization ranged from 22 to 100 mm Hg with a mean gradient of 68 mm Hg. Aortic valve insufficiency was present in 22 patients (69%). Presented in part at the Current Controversies and Techniques in Congenital Heart Surgery Meeting, Baltimore, MD, Sep %9, 1989. Address reprint requests to Dr Clarke, The Children's Hospital, Cardiothoracic Surgery, 8200, 1056 E 19th Ave, Denver, CO 80218.
0 1991 by The Society of
Thoracic Surgeons
Denver have undergone placement of a cryopresewed aortic valve allograft as part of extended aortic root replacement. There were four hospital deaths (13%), and 1child underwent cardiac transplantation 30 hours after operation. In 6 months to 4.8 years of follow-up, a 14-year-old boy with familial hyperlipidemia required coronary artery bypass grafting, and 3 children experienced allograft calcification with progressive insufficiency, which prompted allograft replacement. The other 23 patients are clinically well. (Ann Thorac Surg 1991;52:669-75)
With the exception of 1 patient with Phemolytic streptococci endocarditis, all patients had undergone at least one prior cardiovascular operation. There were 16 previous aortic subvalvar membrane resections or myectomies, 15 aortic valvotomies, and 10 interrupted aortic arch or coarctation repairs. Two patients had required atrial septal defect repair. There were single instances of prior aortic valve replacement, placement of a ventricular apexdescending aorta conduit, atrial and ventricular septa1 defect repair, and creation of a portacaval shunt. The EARR technique emerged when the concepts of aortic root replacement of Somerville and Ross [3] were combined with those of aortoventriculoplasty as described independently by Konno and associates [4] and Rastan and Koncz [5]. Extended aortic root replacement is unique in that a cryopreserved valve allograft is used rather than a mechanical or bioprosthetic valve. The anterior mitral leaflet attached to the aortic valve allograft provides a natural patch with which the subvalvar area in the interventricular septum can be enlarged [6]. In anticipation of EARR, patient weight is used to determine suitable conduit size (Fig 1). During preparations for cardiopulmonary bypass, the allograft is extracted from the liquid nitrogen refrigerator. Still enveloped in three pouches, the valved conduit is thawed in a nonsterile water bath at 37" to 42°C for no longer than 16 minutes. The two outer pouches are removed, and the sterile inner one is passed to the scrub nurse. To dilute the dimethyl sulfoxide cryoprotectant, the graft is rinsed successively in three basins containing increasing concentrations of Dulbecco's medium with a final rinse in lactated Ringer's solution. The allograft is ready for implantation after acquisition of a tissue sample for microbiological culture. The chest is entered through a median sternotomy. After cannulation of the ascending aorta and superior and 0003-4975/91/$3.50
670
CONGENITAL HEART CLARKE EXTENDED AORTIC ROOT REPLACEMENT
Ann Thorac Surg 1991;52:669-75
Fig 1 . Patient weight is used to determine appropriate range of allograft sizes suitable for implantation.
0
4
8
12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 Patient Weight (Kg)
inferior venae cavae, total bypass is initiated. Body temperature is reduced to 20°C. Blood cardioplegia is infused to preserve the myocardium, either anterograde or retrograde through the coronary sinus when there is aortic regurgitation. The incision that begins an EARR is similar to that performed in aortoventriculoplasty. A vertical ascending aortic incision meets an oblique one that traverses the right ventricular outflow tract. They intersect at the aortic annulus between the right and left coronary ostia. From that point, the incision crosses the annulus and divides the interventricular septum. The ascending aorta is transected with subsequent excision of coronary ostial buttons (Fig 2). Native aortic valve leaflets are excised from the annulus, and excess muscle is trimmed from the thawed allograft. The proximal anastomosis commences as allograft and recipient annuli are approximated posteriorly. Their orientation is crucial. The donor right coronary stump is aligned with the recipient left coronary button. Suture lines are continued right and left to the interventricular septum (Fig 3). The donor mitral valve anterior leaflet is modified to allow repair of the septal incision and outflow tract enlargement (Fig 4). The suture line to the right ventricular edge of the septal incision is reinforced with buttressed sutures. Distally, the allograft conduit is severed to provide the exact length necessary to complete its connection to the ascending aorta. The visible valve leaflets must be protected while an aortic punch creates 5- or 6-mm holes in the donor aortic root. Holes are placed in proximity to the coronary ostial buttons to facilitate suturing. To eliminate a potential bleeding source behind the aorta, the donor right coronary stump can be resected to serve as an implantation site for the left coronary button. The distal anastomosis is initiated posteriorly from inside the lumen and progresses to the exterior to complete lateral and anterior connections. After a final warm dose of blood cardioplegia is administered anterograde, the aortic crossclamp is released
Fig 2 An incision similar to that performed in aortoventriculoplasty crosses the aortic annulus and divides the interventricular septum The ascending aorta is transected, and coronary buttons are excised (Reprinted from Clarke DR Extended aortic root replacement for treatment of left ventricular outflow tract obstruction J Cardiac Surg 1987, 2lSuppll 121-8, by permission of Futura Publishing Company, Inc )
CONGENITAL HEART CLARKE EXTENDED AORTIC ROOT REPLACEMENT
Ann Thorac Surg 1991;52669-75
671
A triangular patch cut from the remaining distal allograft aorta is used to repair the right ventricular outflow tract. The base of the patch is sutured to the donor aortic root annulus; tailoring of the corners is done with special care to avoid bleeding (Fig 5). The right ventricular suture line is then completed with the heart beating as rewarming progresses. Temporary pacemaker wires are placed for postoperative management. After the patient is weaned from cardiopulmonary bypass, the operation is completed in standard manner.
Results Aortic valve allografts with an internal diameter of 11 to 25 mm (mean diameter, 19 mm) were implanted. Children weighing as little as 15 kg were able to receive adult-sized allografts. Three patients (9%)died intraoperatively. A 24-year-old man had undergone three previous cardiac surgical procedures. At 4 years of age, he required aortic valvotomy. Eight years later, the aortic valve was replaced, and at age
.-
Fig 4. The anterior leaflet of the donor mitral valve is used to repair the septa1 incision and to enlarge the outflow tract. This portion of the suture line is usually reinforced with pledgeted sutures. (Reprinted from Clarke DR. Extended aortic root replacement for treatment of left ventricular outflow tract obstruction. Cardiac Surg 1987;2[Suppll: 121-8; by permission of Futura Publishing Company, Znc.)
. .. ?. Fig 3 . Allograft and recipient annuli are approximated posteriorly. Suture lines continue right and left to the interventricular septum. (Reprinted from Clarke DR. Extended aortic root replacement for treatment of left ventricular outflow tract obstruction. ] Cardiac Surg 1987;21Suppll:121-8; by permission of Futura Publishing Company, rnc.)
15 years, a ventricular apex-descending aorta conduit was placed. He was seen for his fourth cardiac procedure with severe aortic stenosis and apicoaortic conduit valve insufficiency. On completion of EARR, there was excessive blood loss during takedown of the apicoaortic conduit, and this caused hypotension with subsequent LV failure and death. The second intraoperative death occurred in a 3-yearold girl with a transvalvar aortic gradient of 80 mm Hg, moderate insufficiency, and progressive LV hypertrophy. She had undergone aortic valvotomy at the age of 20 months. Problems were encountered with reimplantation of the left coronary artery, and the child could not be weaned from cardiopulmonary bypass secondary to ischemic contracture. An 11-day-old female neonate had undergone aortic valvotomy on the first day of life. Severe aortic stenosis with LV dysfunction persisted. At the time of EARR, severe (3 to 4 mm thick) endocardia1 fibroelastosis of the left ventricle was discovered. The LV dysfunction caused her death. One hospital death occurred in a 9-year-old boy. He had had prior aortic coarctation repair as well as an LV
672
CONGENITAL HEART CLARKE EXTENDED AORTIC ROOT REPLACEMENT
f
'
Fig 5. Buttons of coronary ostia have been reimplanted, and the distal anastomosis is complete. A triangular patch of distal allograft is used to repair the right ventricular outflow tract. (Reprinted from Clarke DR. Extended aortic root replacement for treatment of left ventricular outflow tract obstruction. J Cardiac Surg 2987;2iSuppll:2228; by permission of Futura Publishing Company, Inc.)
outflow tract myectomy. Reoperation was performed when recurrent subvalvar aortic stenosis in addition to aortic and mitral valve stenosis and pulmonary hypertension developed. At the time of EARR, mitral subvalvar chordal fusion was fenestrated. The postoperative course was marked by hemodynamic deterioration with intermittent stabilization. He died of biventricular failure on the seventh postoperative day. Cardiac transplantation was ultimately done in a 5-yearold child with multilevel aortic stenosis and congenital mitral stenosis. Prior cardiac operations included repair of coarctation of the aorta at 4 days of age and aortic subvalvar membrane resection at 8 months. Mitral valve replacement was performed concurrently with EARR. Intraoperatively, LV failure necessitated the use of an LV assist device. With no improvement in LV function and deteriorating right ventricular function, the child underwent cardiac transplantation 30 hours after the allograft procedure and is alive and well at 6 months' follow-up.
Ann Thorac Surg 1991;52:669-75
Of the other patients, 9 (33%) experienced a benign hospitalization. Although the list of postoperative complications is extensive, the majority were temporary and had resolved by discharge (Table 1). Noteworthy was the development of Serratia marcescens mediastinitis and bacteremia in 1 child, which required debridement and irrigation. A 6-week course of antibiotics was administered. Allograft function was unaffected. The surviving EARR recipients have been followed up clinically for 6 months to 4.8 years (mean follow-up, 2.5 years). Coronary artery bypass grafting was necessary in a 14-year-old boy with familial hyperlipidemia. Six months after allograft placement secondary to a hypoplastic aortic annulus, the child was readmitted with angina pectoris. On cardiac catheterization, a narrowed distal allograft-native aorta anastomosis was evidenced as well as 80% obstruction of the left main coronary artery. Surgical inspection revealed a normal allograft valve with lipid deposits on the intima. The coronary artery lesion was attributed to progression of the hyperlipidemia, as the stenosis was 2 cm from the ostia. The allograft was not replaced. Three infants aged 3, 7, and 12 months experienced allograft calcification, stenosis, and progressive insufficiency, which eventually required reoperation. One child underwent redo EARR 8 months after the initial procedure. Intraoperative findings were compatible with rejection. Calcification involved the allograft conduit wall and right ventricular outflow tract patch; the aortic valve leaflets were fibrotic and retracted. The donor mitral leaflet in the septum was unaffected. Reoperative techniques were identical to those of the first EARR including replacement of the calcified right ventricular outflow tract patch to allow implantation of a larger conduit. Administration of cyclosporine was initiated concurrent with the implantation of a second allograft. Twenty-one months later, the child is normally active and asymptomatic.
Table 1 . Early Postoperative Complications of Extended Aortic Root Replacement Complication Transient heart block Bleeding leading to reoperation Postpericardiotomy syndrome Arrhythmias Pleural effusion Serratia marcescens mediastinitis Superficial wound infection Right phrenic nerve palsy Incisional ventral hernia Pericardial effusion Dialysis and ventilatory support Mucous secretions leading to bronchoscopy Atelectasis No complications
No. of Patients
4 3 3 3 2
1 1 1 1 1 1 1 1
9
CONGENITAL HEART CLARKE EXTENDED AORTIC ROOT REPLACEMENT
Ann Thorac Surg 1991:52:669-75
Table 2 . Most Recent Echocardiographic Evaluation After Extended Aortic Root Replacement Variable Left ventricular function Good Depressed Aortic stenosis None Mild Moderate Aortic insufficiency None Mild Moderate
No. of Patients 21 2 10 12 1 6 15 2
Of the 2 other patients who required allograft replacement, 1 infant received a mechanical aortic valve prosthesis through an aortoventriculoplasty technique 37 months after EARR. The other underwent a pulmonary autograft procedure [7, 81 39 months after allograft insertion. In each case, the calcified right ventricular outflow tract patch was replaced. Twenty-three survivors continue to lead clinically asymptomatic lives. Most recent echocardiographic evaluations at 6 months to 3.9 years (mean duration, 1.9 years) after EARR reveal mild aortic stenosis or insufficiency or both to be common. Left ventricular function is good in 21 (91%) of these patients (Table 2).
Comment Cryopreserved aortic valve allografts have enhanced the surgeon’s ability to correct extremely complex congenital cardiac anomalies. At times, they are the only available surgical option. The EARR technique is straightforward, prolonged or severe early postoperative complications are not excessive, and permanent complete heart block has not occurred. Of primary concern are the early allograft failures. Seven children less than 3 years old had EARR with one hospital death. Three of the other 6 children have ultimately required allograft replacement. This trend will be monitored intensively. In young patients, immunosup-
673
pressive therapy with low-dose cyclosporine or use of the pulmonary autograft procedure [8] are alternatives worthy of consideration. After nearly 5 years of follow-up, it is impossible to adequately answer the question posed by the title of this article. The long-term fate of allografts used in EARR procedures remains undetermined. Improved techniques of cryopreservation provide superior tissue viability, which may produce increased allograft durability [9]. Intermediate follow-up of aortic allograft valved conduits in the LV outflow tract is generally favorable. This observation in conjunction with the immediate advantages such as their relative ease of insertion, their versatility and resistance to infection, the avoidance of anticoagulation in the pediatric population, and the ability to implant adult sizes in children certainly justifies their continued use for LV outflow tract reconstruction, particularly in the older child.
References 1. Murray G. Homologous aortic valve segment transplants as surgical treatment for aortic and mitral insufficiency. Angiology 1956;7:466-71. 2. Matsuki 0, Robles A, Gibbs S, Bodnar E, Ross DN. Long-term performance of 555 aortic homografts in the aortic position. Ann Thorac Surg 1988;46:187-91. 3. Somerville J, Ross D. Homograft replacement of aortic root with reimplantation of coronary arteries. Results after one to five years. Br Heart J 1982;47473-82. 4. Konno S, Imai J, Iida Y, et al. A new method for prosthetic valve replacement in congenital aortic stenosis associated with hypoplasia of the aortic valve ring. J Thorac Cardiovasc Surg 1975;70:909-17. 5. Rastan H, Koncz J. Aortoventriculoplasty. A new technique for the treatment of left ventricular outflow tract obstruction. J Thorac Cardiovasc Surg 1976;71:920-7. 6. Clarke DR. Extended aortic root replacement in 12 patients with complex left ventricular outflow tract obstruction. In: Yankah AC, Hetzer R, Miller DC, et al, eds. Cardiac valve allografts 1962-1987: current concepts on the use of aortic and pulmonary allografts for heart valve substitutes. New York: Springer-Verlag, 1988:15745. 7. Stelzer P, Jones DJ, Elkins RC. Aortic root replacement with pulmonary autograft. Circulation 1989;8O(Suppl3):209-13. 8. Matsuki 0, Okita Y, Almeida RS, et al. Two decades’ experience with aortic valve replacement with pulmonary autograft. J Thorac Cardiovasc Surg 1988;95:70511. 9. O‘Brien MF, Stafford G, Gardner M, et al. The viable cryopreserved allograft aortic valve. J Cardiac Surg 1987;1:153-67.
COMMENTARY: Homograft Aortic Root Replacement I read with interest Dr Clarke’s paper on extended aortic root replacement and have heard him talk on the subject on a number of occasions. We are in complete agreement on the advantages of using an adult-sized homograft root that the child will grow into rather than a small mechan-
ical valve that the child will outgrow and therefore be seen later with an obstructive prosthesis. The homograft is the only biological valve (apart from the pulmonary autograft) applicable to children, and because it is inserted as a complete functional entity and is not distorted by sur-