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Late results after right ventricular outflow tract reconstruction with aortic root homografts
Late results after right ventricular outflow tract reconstruction with aortic root homografts Robert K. Brawley, M.D., Timothy J. Gardner, M.D., James S. Donahoo, M.D., Catherine A. Neill, M.D., Richard D. Rowe, M.D., and Vincent L. Gott, M.D., Baltimore, Md.
XXomografts of the ascending aorta that include the aortic valve have now been used to reconstruct the right ventricular outflow tract in a number of patients with congenital malformations of the heart. Anatomic corrections by means of aortic root homografts have been reported in patients who have transposition of the great arteries in association with ventricular septal defect and subpulmonary stenosis, 5 ' ie in patients who have truncus arteriosus,r>-13>21 and in certain patients who have Fallot's tetralogy.3' 19>20 Substantial enthusiasm has been generated by the excellent function of aortic root homografts immediately after operation and by the good initial results obtained in these patients, many of whom were previously considered to have uncorrectable lesions. From the outset, however, there have been reservation and concern regarding the long-term durability and function of aortic root homografts. The widely recognized failure of arterial homografts used in From the Departments of Surgery and Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Md. 21205. Received for publication May 5, 1972. Address for reprints: Robert K. Brawley, M.D., The Johns Hopkins Hospital, Baltimore, Md. 21205.
3 14
the past for peripheral vascular reconstructions has contributed in large measure to the skepticism toward aortic root homografts in the outflow portion of the right ventricle. In the present report, followup data obtained from 8 patients who survived cardiac reconstructions with aortic root homografts are presented. Clinical material Aortic root homografts were used to reconstruct the right ventricular outflow tracts of 12 patients at The Johns Hopkins Hospital during the 5 years between November, 1966, and December, 1971. These homografts consisted of ascending aortas that contained the aortic valve. They were obtained from cadavers and were sterilized and preserved by one of three different methods (Table I ) . The aortic leaflet of the mitral valve was also included in most of the homografts used. Eight of the patients survived operation and the immediate postoperative period and have been followed from 6 to 59 months after operation. The techniques used for cardiac reconstruction and the initial results in 6 of the patients have been previously reported. 3 ' 20 ' 21 One of the 8 patients, an 11-year-old
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boy, had truncus arteriosus. A normal circulation was established in this patient by detachment of the pulmonary arteries from the truncus, right ventricular myomectomy, closure of the ventricular septal defect, and insertion of an aortic root homograft containing an aortic valve between the right ventricle and the pulmonary arteries.21 This patient died 6 months after the operation. Two months prior to his death, cardiac catheterization was performed. The pulmonary artery pressure was 96/18 mm. Hg, and there was no evidence of an intracardiac shunt. Mild pulmonary valvular insufficiency was demonstrated. Postmortem examination showed far-advanced pulmonary vascular changes in the lungs, but the homograft was intact with no evidence of destruction of the valve tissue. Although this patient died of severe pulmonary hypertension a few months after operation, the aortic root homograft had allowed the reconstruction of the right ventricular outflow tract and had functioned well until his sudden death. The other 7 patients had tetralogy of Fallot malformations with right ventricular outflow tracts that could not be satisfactorily reconstructed with conventional methods of tetralogy repair. One of the 7 had congenital absence of the pulmonary valve. Three others had grossly malformed or atretic pulmonary valves; in these cases, total correction of the tetralogy by the usual operative techniques would have resulted in severe pulmonary regurgitation. Malformations, either congenital or acquired, of the main and/or right and left pulmonary arteries were the indication for insertion of the aortic root homograft in the remaining 3 patients. One of the patients with tetralogy of Fallot also died 6 months after total correction and reconstruction of the right ventricular outflow tract witii an aortic root homograft. The homograft, obtained from a cadaver, had been sterilized with betapropiolactone and stored at 4° C. Initially, the patient's condition improved considerably, but 3 months after operation she developed congestive heart failure
and became febrile. Streptococci were grown from blood cultures. She was treated with antibiotics and became afebrile. Cardiac catheterization, performed 5 months after operation, demonstrated a small residual left-to-right shunt, moderate bifurcation stenosis of the pulmonary artery, and what appeared to be a well-functioning homograft valve. Three weeks later, the patient had a sudden cardiac arrest from which she never recovered. Postmortem examination revealed a probe-patent residual ventricular septal defect and complete destruction of the valve leaflets of the homograft with calcification and scarring of the leaflet remnants. The findings were interpreted as bacterial destruction of the homograft valve leaflets. Another of the patients with tetralogy of Fallot malformation was operated upon in February, 1967. Total correction was achieved with the use of an aortic root homograft for reconstruction of the right ventricular outflow tract. The aortic homograft had been sterilized with betapropiolactone and preserved in refrigerated Hanks solution. At this time, nearly 5 years after the open-heart operation, the patient is asymptomatic and has no clinical evidence of pulmonary regurgitation. Calcification in the region of the aortic homograft is not present on chest x-ray films. He has refused postoperative cardiac catheterization. The remaining 5 patients with tetralogy of Fallot malformations have been followed 17, 18, 25, 54, and 59 months after total correction and right ventricular outflow tract reconstruction with aortic root homografts, and all have recently undergone postoperative cardiac catheterization (Table I ) . Severe pulmonary insufficiency is not evident clinically in any of the 5 patients. Three of them are asymptomatic and appear to have an excellent result 17, 25, and 54 months after operation. One of the other 2 is doing well 59 months after operation but has evidence of a moderate-sized residual left-to-right shunt both clinically and by cardiac catheterization. In this pa-
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Thoracic and Cardiovascular Surgery
Table I
Patient
Age at operation (years)
Homograft treatment*
Diagnosis
Duration of follow-up (months)
Status
L. H. (126 89 64)
11
Type 1
TA
6
Died with pulmonary hypertension
C. W. ( 95 86 91)
11
Type 2
T/F
6
Died after SBE
M. L. ( 90 16 76)
22
Type 1
T/F
17
Excellent
P. H. ( 95 12 39)
16
Type 1
T/F
18
Good after SBE
F.W. ( 38 05 05)
28
Type 1
T/F
25
Excellent
M. M. ( 83 90 80)
15
Type 1
T/F
54
Excellent
D.T. ( 47 50 97)
23
Type 3
T/F
57
Excellent
D. K. ( 95 62 99)
9
Type 2
T/F
59
Good
Legend: TA, Truncus arteriosus. T / F , Tetralogy of Fallot. SBE, Subacute bacterial endocarditis. RV, Right ventricle. PA •Type 1, Homograft preserved by freezing at -70° C. and sterilized in the frozen state in an electron-beam accelerator which deliver with betapropiolactone and preserved in refrigerated Hanks solution.
tient, pulmonary regurgitation was estimated to be trivial by angiocardiography. The final patient (P.H.) did extremely well for 15 months following operation. Cardiac catheterization 1 year postoperatively demonstrated trivial pulmonary regurgitation. How ever, 2 months after postoperative cardiac catheterization, she developed subacute bacterial endocarditis and azotemia. She responded to antibiotic therapy and recovered from the endocarditis. At the present time, she has no clinical evidence of pulmonary regurgitation and is doing well. Calcification in the wall of the aortic root homograft has been demonstrated by chest x-ray films and cardiac fluoroscopy in only 1 of the 6 surviving patients (Fig. 1). This calcification is in the homograft wall and does not appear to involve the valve leaflets. Of the 5 patients who underwent postoperative cardiac catheterization, all have residual right ventricular hypertension and right ventricular-pulmonary artery pressure gradients. Right ventricular pres-
sures ranged from 54 to 92 mm. Hg, and pressure gradients between the right ventricle and the pulmonary artery ranged from 29 to 62 mm. Hg. The precise location of these pressure gradients could not be determined. In 3 patients, angiography demonstrated narrowing at the distal anastomosis between the aortic root homograft and the pulmonary artery (Figs. 2 and 3). A pressure gradient of 62 mm. Hg was thought to be located at the junction of aortic root homograft and right ventricle or the crista supraventricularis in the fourth patient (M. M.) in the fifth patient (D.K.), a gradient of 29 mm. Hg was probably located at the level of the pulmonary artery annulus. In this patient, who had a diagnosis of tetralogy of Fallot and congenital absence of the pulmonary valve, the pulmonary valve ring was not incised at the time of operation, and the aortic root homograft was inserted distal to the patient's pulmonary annulus. In Patient M.M. and D.K., it is conceivable that the homograft valve is, in fact,
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Postoperative RV pressure (mm. Hg)
RV-PA gradient (mm. Hg)
cardiac
catheterization
Probable location gradient
of
Estimate of PI
Comments Homograft was intact with normal-appearing valve leaflets at autopsy Homograft valve leaflets found to be destroyed and calcified at autopsy
59
38
Distal anastomosis
Trivial
74
36
Distal anastomosis
Trivial
68
31
Distal anastomosis
Trivial
92
62
Proximal anastomosis or crista
Trivial
Developed SBE 15 months after operation; recovered
Patient has refused postoperative cardiac catheterization 54
29
Pulmonary annulus
Trivial
Residual VSD
Pulmonary artery. PI, Pulmonary insufficiency. VSD, Ventricular septal defect. 2 megarads in 12 seconds. Type 2, Homograft sterilized with betapropiolactone and stored at 4° C. Type 3, Homograft sterilized
stenotic. However, by cineangiograms the homograft valves appear to open well, and the areas of stenosis are therefore thought to be just proximal to the homograft valve in both patients. Pulmonary regurgitation was considered to be trivial by angiography in the 5 patients who underwent postoperative cardiac catheterizations (Fig. 3). Dicussion In this clinic, 8 patients have survived operations in which a homograft of the ascending aorta that included an aortic valve was utilized to reconstruct the outflow portion of the right ventricle (Table I ) . Two of these patients died 6 months after operation. In 1 of them, the homograft valve was completely destroyed, presumably due to infection. In the second patient, who died of severe and persistent pulmonary hypertension, the aortic root homograft, including the aortic valve, was intact and appeared to be functional. The current clinical status of the 6 surviving patients is
good or excellent 17 to 59 months after operation. Although the presence of persistent right ventricular hypertension and pressure gradients between the right ventricle and the distal pulmonary arteries has been disappointing, the results of operation are acceptable in this small series of patients. Calcification has been seen in only 1 of the 6 patients, and, in this case, the calcification appears to be in the wall of the homograft aorta and not within the valve leaflets. In the entire series, homograft malfunction has contributed to death only once, in the 1 patient in whom the aortic root homograft was destroyed by bacteria. Significant valvular insufficiency has not been demonstrated in any other patient. Late failure of arterial homografts used for peripheral vascular reconstruction has been responsible for much of the pessimism concerning the long-term fate of aortic root homografts in the pulmonary area."' 1 4 The development of thromboses, aneurysms,
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Fig. 1. Frontal (A) and lateral (B) chest x-ray films of Patient M. M. taken almost 5 years after operation. Arrows indicate calcification in the wall of the aortic root homograft, which was used to reconstruct the right ventricular outflow tract of this patient.
and calcification in aortic and arterial homografts has been used as evidence to argue against the durability and continued function of aortic root homografts. Mead and colleagues14 reported the microscopic findings obtained in seventy-five arterial homografts removed from patients as long as 9 years after insertion. The homografts were found to be fibrous tubes lined with pseudoendothelium and surrounded by dense scar tissue. They were noted to be rigid and inflexible. It has been reported that the arterial homograft wall frequently becomes calcified.' Careful analysis of the reported long-term results of arterial homografts reveals that homografts composed of iliac and femoral arteries often failed because of thrombosis or aneurysm formation, whereas homografts consisting only of aortic segments rarely developed these complications. Knox and Miller,11 reporting on long-term appraisal of aortic and arterial homografts, found no aneurysms in any of the bifurcation aortic grafts, although wall calcification was present without exception at the time of death. Mead's
group11 found no instance of aneurysm in aortic sleeve grafts or in the aortic portion of a bifurcation graft. Brock4 followed patients for from 8 to 17 years and reported excellent functional results in cases in which aortic segment homografts were used to replace a portion of aorta resected for aneurysm or for coarctation. However, there was a high incidence of homograft calcification in these patients. It would appear from these reports that in most instances aortic segment homografts are transformed by the recipient into fibrous tubes that contain wall calcification, are lined with pseudoendothelium, and are surrounded by scar. In spite of these degenerative changes, the aortic segment homograft
can
be
expected
to
function
satisfactorily as a conduit for blood for a long period of time.
Although the reported experience with aortic valve homografts in the subcoronary aortic position varies,2, ir>*1S satisfactory function of the homograft valve for extended periods of time has been observed.15'1S At present, there is no reported evidence
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, ^MV^^M^'i*
Fig. 2. Right ventriculogram in Patient P. H. 1 year after operation. The right ventricle (R.V.), aortic root homograft, and pulmonary artery (P.A.) are filled with dye, and mild stenoses are present at the proximal and distal homograft anastomoses.
Fig. 3. Dye injection into the aortic root homograft in Patient M. L. 1 year after operation. The absence of dye in the right ventricle (R.V.) when the homograft and pulmonary artery (P.A.) are well filled demonstrates competency of the homograft valve.
to demonstrate that a composite homograft which includes a segment of the ascending aorta and an aortic valve will function less well than either of its components used alone. The reports of Brock,4 Reichenbach and colleagues,17 and Angell and colleagues1 suggest a possible advantage in the use of fresh rather than freeze-dried homograft material, because degenerative changes in the homograft may be diminished and partial replacement of donor graft cells with host cells may be possible. Any criticism of the use of aortic root homografts for reconstruction of the right ventricular outflow tract must take into consideration alternative methods of treatment. Currently, the alternative to the use of aortic root homografts for the correction of truncus arteriosus is the use of a tube made of prosthetic or autologous material and containing a valve composed of prosthetic, homologous, or autologous material.7' s- "' A similar alternative would be required for the anatomic correction of transposition of the great arteries with ventricular septal defect and pulmonary stenosis in patients in whom construction of an intra-atrial baffle, closure of the ventricular septal defect, and relief of pulmonary obstruction6 were not possible. In a
small portion of patients with tetralogy of Fallot, total correction which provides adequate relief of right ventricular outflow tract obstruction produces severe pulmonary valvular insufficiency because of the absence of any functional pulmonic valve. 3 '"' 2 " Furthermore, in some patients with tetralogy, it is impossible for incisions in the right ventricular outflow tract to be extended from the right ventricle through the pulmonary valve annulus and into the pulmonary artery because of an anomalous coronary artery which traverses the outflow tract. Total correction by conventional methods is not possible in other patients with Fallot's malformation because of the absence of any connection between the right ventricle and pulmonary arteries (pulmonary atresia). 10 The alternative to the use of aortic root homografts in these patients is the acceptance of marked pulmonary incompetence or reconstruction with prosthetic, homograft, or autologous material alone or in various combinations. 7 - 8 ' 10 ' 12 Aortic root homografting compares favorably with these alternatives, which are all clearly less than ideal. Based upon these considerations and upon the experience reported above, continued use of aortic root homografts for reconstruction of the pulmonary artery, pulmonary valve, and out-
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flow portion of the right ventricle appears to be indicated in certain patients. Summary Late results are presented in 8 patients who survived operation during which a homograft of the ascending aorta that included the aortic valve was used to reconstruct the outflow tract of the right ventricle. Two of the patients died 6 months after operation; the homograft valve was destroyed, presumably by bacteria, in 1 patient but appeared to be functional in the other. The remaining 6 patients have been followed from 17 to 59 months postoperatively. The clinical status of these 6 patients is good or excellent. Cardiac catheterizations, performed a year or more following operation in 5 of the patients, have demonstrated that the aortic root homografts are functioning well. The experience with this small group of patients suggests that aortic root homografts, when used for reconstruction of the right ventricular outflow tract, function satisfactorily for long periods of time in certain patients with congenital malformations of the heart.
REFERENCES
1 Angell, W. W., Stinson, E. B., Iben, A. B., and Shumway, N. E.: Multiple Valve Replacement With Fresh Aortic Homograft, J. THORAC. CARDIOVASC. SURG. 56: 323, 1968.
2 Beach, P. M., Bowman, F. O., Kaiser, G. A., and Malm, J. R.: Aortic Valve Replacement Using Frozen Irradiated Homografts: LongTerm Evaluation, Circulation. In press. 3 Bender, H. W., Jr., Haller, J. A., Jr., Brawley, R. K., Humphries, J. O., Neill, C. A., and Gott, V. L.: Experience in Repair of Tetralogy of Fallot Malformation in Adults, Ann. Thorac. Surg. 11: 508, 1971. 4 Brock, R. C : Long-Term Degenerative Changes in Aortic Segment Homografts With Particular Reference to Calcification, Thorax 23: 249, 1968. 5 Ching, E., DuShane, J. W., McGoon, D. C , and Danielson, G. K.: Total Correction of Cardiac Anomalies in Infancy Using Extracorporeal Circulation, J. THORAC. CARDIOVASC. SURG. 62: 117, 1971.
Thoracic and Cardiovascular Surgery
6 Daicoff, G. R., Schiebler, G. L., Elliott, L. P., Van Mierop, H. S., Bartley, T. D., Gessner, I. H., and Wheat, M. W., Jr.: Surgical Repair of Complete Transposition of the Great Arteries With Pulmonary Stenosis, Ann. Thorac. Surg. 7: 529, 1969. 7 Duran, C. M., Whitehead, R., and Gunning, A. J.: Implantation of Homologous and Heterologous Aortic Valves in Prosthetic Vascular Tubes, Thorax 24: 142, 1969. 8 Gott, V. L., Daggett, R. L., Koepke, D. E., Rowe, G. G., and Young, W. P.: Replacement of the Canine Pulmonary Valve and Pulmonary Artery With Graphite-Coated Valve Prosthesis, J. THORAC. CARDIOVASC. SURG. 44:
713, 1962. 9 Hawe, A., Rastelli, G. C , Ritter, D. G., DuShane, J. W., and McGoon, D. C : Management of the Right Ventricular Outflow Tract in Severe Tetralogy of Fallot, J. THORAC CARDIOVASC SURG. 60: 131, 1970.
10 Horiuchi, R., Abe, T., Okada, Y., Kuribayashi, R., Suzuki, Y., and Ishizawa, E.: Reconstruction of the Main Pulmonary Artery With a Valve-Bearing Tube Graft Made of Autologous Pericardium, J. THORAC CARDIOVASC SURG. 62: 793, 1971.
11 Knox, W. G., and Miller, R. E.: Long-Term Appraisal of Aortic and Arterial Homografts Implanted in Years 1954-1957, Ann. Surg. 172: 1076, 1970. 12 Marchand, P.: The Use of a Cusp-Bearing Homograft Patch to the Outflow Tract and Pulmonary Artery in Fallot's Tetralogy and Pulmonary Valvular Stenosis, Thorax 22: 497, 1967. 13 McGoon, D. C , Rastelli, G. C , and Ongley, P. A.: An Operation for the Correction of Truncus Arterious, J. A. M. A. 205: 59, 1968. 14 Mead, J. W., Linton, R. R., Darling, R. C , and Menendez, C. V.: Arterial Homografts, Arch. Surg. 93: 392, 1966. 15 Pacifico, A. D., Karp, R. B., and Kirklin, J. W.: A Comparison of Homografts and StarrEdwards Prostheses for Aortic Valve Replacement, Circulation. In press. 16 Rastelli, G. C , McGoon, D. C , and Wallace, R. B.: Anatomic Correction of Transposition of the Great Arteries With Ventricular Septal Defect and Subpulmonary Stenosis, J. THORAC CARDIOVASC SURG. 58: 545, 1969.
17 Reichenbach, D. D., Mohri, H., Sands, M., and Merendino, K. A.: Viability of Connective Tissue Cells Following Storage of Aortic Valve Leaflets,
J. THORAC. CARDIOVASC SURG. 62:
690, 1971. 18 Ross, D. N.: Biological Valves: Their Performance and Prospects, Circulation. In press.
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19 Ross, D. N., and Somerville, J.: Correction of Pulmonary Atresia With a Homograft Aortic Valve, Lancet 2: 1446, 1966. 20 Weldon, C. S., Rowe, R. D., and Gott, V. L.: Clinical Experience With the Use of Aortic Valve Homografts for Reconstruction of the
Pulmonary Artery, Pulmonary Valve, and Outflow Portion of the Right Ventricle, Circulation 37: 51, 1968 (Suppl. 2). 21 Weldon, C. S., and Cameron, J. L.: Correction of Persistent Truncus Arteriosus, J. Cardiovasc. Surg. 9: 2, 1968.
XXomografts of the ascending aorta that include the aortic valve have now been used to reconstruct the right ventricular outflow tract in a number of patients with congenital malformations of the heart. Anatomic corrections by means of aortic root homografts have been reported in patients who have transposition of the great arteries in association with ventricular septal defect and subpulmonary stenosis, 5 ' ie in patients who have truncus arteriosus,r>-13>21 and in certain patients who have Fallot's tetralogy.3' 19>20 Substantial enthusiasm has been generated by the excellent function of aortic root homografts immediately after operation and by the good initial results obtained in these patients, many of whom were previously considered to have uncorrectable lesions. From the outset, however, there have been reservation and concern regarding the long-term durability and function of aortic root homografts. The widely recognized failure of arterial homografts used in From the Departments of Surgery and Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Md. 21205. Received for publication May 5, 1972. Address for reprints: Robert K. Brawley, M.D., The Johns Hopkins Hospital, Baltimore, Md. 21205.
3 14
the past for peripheral vascular reconstructions has contributed in large measure to the skepticism toward aortic root homografts in the outflow portion of the right ventricle. In the present report, followup data obtained from 8 patients who survived cardiac reconstructions with aortic root homografts are presented. Clinical material Aortic root homografts were used to reconstruct the right ventricular outflow tracts of 12 patients at The Johns Hopkins Hospital during the 5 years between November, 1966, and December, 1971. These homografts consisted of ascending aortas that contained the aortic valve. They were obtained from cadavers and were sterilized and preserved by one of three different methods (Table I ) . The aortic leaflet of the mitral valve was also included in most of the homografts used. Eight of the patients survived operation and the immediate postoperative period and have been followed from 6 to 59 months after operation. The techniques used for cardiac reconstruction and the initial results in 6 of the patients have been previously reported. 3 ' 20 ' 21 One of the 8 patients, an 11-year-old
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boy, had truncus arteriosus. A normal circulation was established in this patient by detachment of the pulmonary arteries from the truncus, right ventricular myomectomy, closure of the ventricular septal defect, and insertion of an aortic root homograft containing an aortic valve between the right ventricle and the pulmonary arteries.21 This patient died 6 months after the operation. Two months prior to his death, cardiac catheterization was performed. The pulmonary artery pressure was 96/18 mm. Hg, and there was no evidence of an intracardiac shunt. Mild pulmonary valvular insufficiency was demonstrated. Postmortem examination showed far-advanced pulmonary vascular changes in the lungs, but the homograft was intact with no evidence of destruction of the valve tissue. Although this patient died of severe pulmonary hypertension a few months after operation, the aortic root homograft had allowed the reconstruction of the right ventricular outflow tract and had functioned well until his sudden death. The other 7 patients had tetralogy of Fallot malformations with right ventricular outflow tracts that could not be satisfactorily reconstructed with conventional methods of tetralogy repair. One of the 7 had congenital absence of the pulmonary valve. Three others had grossly malformed or atretic pulmonary valves; in these cases, total correction of the tetralogy by the usual operative techniques would have resulted in severe pulmonary regurgitation. Malformations, either congenital or acquired, of the main and/or right and left pulmonary arteries were the indication for insertion of the aortic root homograft in the remaining 3 patients. One of the patients with tetralogy of Fallot also died 6 months after total correction and reconstruction of the right ventricular outflow tract witii an aortic root homograft. The homograft, obtained from a cadaver, had been sterilized with betapropiolactone and stored at 4° C. Initially, the patient's condition improved considerably, but 3 months after operation she developed congestive heart failure
and became febrile. Streptococci were grown from blood cultures. She was treated with antibiotics and became afebrile. Cardiac catheterization, performed 5 months after operation, demonstrated a small residual left-to-right shunt, moderate bifurcation stenosis of the pulmonary artery, and what appeared to be a well-functioning homograft valve. Three weeks later, the patient had a sudden cardiac arrest from which she never recovered. Postmortem examination revealed a probe-patent residual ventricular septal defect and complete destruction of the valve leaflets of the homograft with calcification and scarring of the leaflet remnants. The findings were interpreted as bacterial destruction of the homograft valve leaflets. Another of the patients with tetralogy of Fallot malformation was operated upon in February, 1967. Total correction was achieved with the use of an aortic root homograft for reconstruction of the right ventricular outflow tract. The aortic homograft had been sterilized with betapropiolactone and preserved in refrigerated Hanks solution. At this time, nearly 5 years after the open-heart operation, the patient is asymptomatic and has no clinical evidence of pulmonary regurgitation. Calcification in the region of the aortic homograft is not present on chest x-ray films. He has refused postoperative cardiac catheterization. The remaining 5 patients with tetralogy of Fallot malformations have been followed 17, 18, 25, 54, and 59 months after total correction and right ventricular outflow tract reconstruction with aortic root homografts, and all have recently undergone postoperative cardiac catheterization (Table I ) . Severe pulmonary insufficiency is not evident clinically in any of the 5 patients. Three of them are asymptomatic and appear to have an excellent result 17, 25, and 54 months after operation. One of the other 2 is doing well 59 months after operation but has evidence of a moderate-sized residual left-to-right shunt both clinically and by cardiac catheterization. In this pa-
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Table I
Patient
Age at operation (years)
Homograft treatment*
Diagnosis
Duration of follow-up (months)
Status
L. H. (126 89 64)
11
Type 1
TA
6
Died with pulmonary hypertension
C. W. ( 95 86 91)
11
Type 2
T/F
6
Died after SBE
M. L. ( 90 16 76)
22
Type 1
T/F
17
Excellent
P. H. ( 95 12 39)
16
Type 1
T/F
18
Good after SBE
F.W. ( 38 05 05)
28
Type 1
T/F
25
Excellent
M. M. ( 83 90 80)
15
Type 1
T/F
54
Excellent
D.T. ( 47 50 97)
23
Type 3
T/F
57
Excellent
D. K. ( 95 62 99)
9
Type 2
T/F
59
Good
Legend: TA, Truncus arteriosus. T / F , Tetralogy of Fallot. SBE, Subacute bacterial endocarditis. RV, Right ventricle. PA •Type 1, Homograft preserved by freezing at -70° C. and sterilized in the frozen state in an electron-beam accelerator which deliver with betapropiolactone and preserved in refrigerated Hanks solution.
tient, pulmonary regurgitation was estimated to be trivial by angiocardiography. The final patient (P.H.) did extremely well for 15 months following operation. Cardiac catheterization 1 year postoperatively demonstrated trivial pulmonary regurgitation. How ever, 2 months after postoperative cardiac catheterization, she developed subacute bacterial endocarditis and azotemia. She responded to antibiotic therapy and recovered from the endocarditis. At the present time, she has no clinical evidence of pulmonary regurgitation and is doing well. Calcification in the wall of the aortic root homograft has been demonstrated by chest x-ray films and cardiac fluoroscopy in only 1 of the 6 surviving patients (Fig. 1). This calcification is in the homograft wall and does not appear to involve the valve leaflets. Of the 5 patients who underwent postoperative cardiac catheterization, all have residual right ventricular hypertension and right ventricular-pulmonary artery pressure gradients. Right ventricular pres-
sures ranged from 54 to 92 mm. Hg, and pressure gradients between the right ventricle and the pulmonary artery ranged from 29 to 62 mm. Hg. The precise location of these pressure gradients could not be determined. In 3 patients, angiography demonstrated narrowing at the distal anastomosis between the aortic root homograft and the pulmonary artery (Figs. 2 and 3). A pressure gradient of 62 mm. Hg was thought to be located at the junction of aortic root homograft and right ventricle or the crista supraventricularis in the fourth patient (M. M.) in the fifth patient (D.K.), a gradient of 29 mm. Hg was probably located at the level of the pulmonary artery annulus. In this patient, who had a diagnosis of tetralogy of Fallot and congenital absence of the pulmonary valve, the pulmonary valve ring was not incised at the time of operation, and the aortic root homograft was inserted distal to the patient's pulmonary annulus. In Patient M.M. and D.K., it is conceivable that the homograft valve is, in fact,
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Postoperative RV pressure (mm. Hg)
RV-PA gradient (mm. Hg)
cardiac
catheterization
Probable location gradient
of
Estimate of PI
Comments Homograft was intact with normal-appearing valve leaflets at autopsy Homograft valve leaflets found to be destroyed and calcified at autopsy
59
38
Distal anastomosis
Trivial
74
36
Distal anastomosis
Trivial
68
31
Distal anastomosis
Trivial
92
62
Proximal anastomosis or crista
Trivial
Developed SBE 15 months after operation; recovered
Patient has refused postoperative cardiac catheterization 54
29
Pulmonary annulus
Trivial
Residual VSD
Pulmonary artery. PI, Pulmonary insufficiency. VSD, Ventricular septal defect. 2 megarads in 12 seconds. Type 2, Homograft sterilized with betapropiolactone and stored at 4° C. Type 3, Homograft sterilized
stenotic. However, by cineangiograms the homograft valves appear to open well, and the areas of stenosis are therefore thought to be just proximal to the homograft valve in both patients. Pulmonary regurgitation was considered to be trivial by angiography in the 5 patients who underwent postoperative cardiac catheterizations (Fig. 3). Dicussion In this clinic, 8 patients have survived operations in which a homograft of the ascending aorta that included an aortic valve was utilized to reconstruct the outflow portion of the right ventricle (Table I ) . Two of these patients died 6 months after operation. In 1 of them, the homograft valve was completely destroyed, presumably due to infection. In the second patient, who died of severe and persistent pulmonary hypertension, the aortic root homograft, including the aortic valve, was intact and appeared to be functional. The current clinical status of the 6 surviving patients is
good or excellent 17 to 59 months after operation. Although the presence of persistent right ventricular hypertension and pressure gradients between the right ventricle and the distal pulmonary arteries has been disappointing, the results of operation are acceptable in this small series of patients. Calcification has been seen in only 1 of the 6 patients, and, in this case, the calcification appears to be in the wall of the homograft aorta and not within the valve leaflets. In the entire series, homograft malfunction has contributed to death only once, in the 1 patient in whom the aortic root homograft was destroyed by bacteria. Significant valvular insufficiency has not been demonstrated in any other patient. Late failure of arterial homografts used for peripheral vascular reconstruction has been responsible for much of the pessimism concerning the long-term fate of aortic root homografts in the pulmonary area."' 1 4 The development of thromboses, aneurysms,
3 18
The Journal of
Brawley et al.
Thoracic and Cardiovascular Surgery
Fig. 1. Frontal (A) and lateral (B) chest x-ray films of Patient M. M. taken almost 5 years after operation. Arrows indicate calcification in the wall of the aortic root homograft, which was used to reconstruct the right ventricular outflow tract of this patient.
and calcification in aortic and arterial homografts has been used as evidence to argue against the durability and continued function of aortic root homografts. Mead and colleagues14 reported the microscopic findings obtained in seventy-five arterial homografts removed from patients as long as 9 years after insertion. The homografts were found to be fibrous tubes lined with pseudoendothelium and surrounded by dense scar tissue. They were noted to be rigid and inflexible. It has been reported that the arterial homograft wall frequently becomes calcified.' Careful analysis of the reported long-term results of arterial homografts reveals that homografts composed of iliac and femoral arteries often failed because of thrombosis or aneurysm formation, whereas homografts consisting only of aortic segments rarely developed these complications. Knox and Miller,11 reporting on long-term appraisal of aortic and arterial homografts, found no aneurysms in any of the bifurcation aortic grafts, although wall calcification was present without exception at the time of death. Mead's
group11 found no instance of aneurysm in aortic sleeve grafts or in the aortic portion of a bifurcation graft. Brock4 followed patients for from 8 to 17 years and reported excellent functional results in cases in which aortic segment homografts were used to replace a portion of aorta resected for aneurysm or for coarctation. However, there was a high incidence of homograft calcification in these patients. It would appear from these reports that in most instances aortic segment homografts are transformed by the recipient into fibrous tubes that contain wall calcification, are lined with pseudoendothelium, and are surrounded by scar. In spite of these degenerative changes, the aortic segment homograft
can
be
expected
to
function
satisfactorily as a conduit for blood for a long period of time.
Although the reported experience with aortic valve homografts in the subcoronary aortic position varies,2, ir>*1S satisfactory function of the homograft valve for extended periods of time has been observed.15'1S At present, there is no reported evidence
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August, 1972
, ^MV^^M^'i*
Fig. 2. Right ventriculogram in Patient P. H. 1 year after operation. The right ventricle (R.V.), aortic root homograft, and pulmonary artery (P.A.) are filled with dye, and mild stenoses are present at the proximal and distal homograft anastomoses.
Fig. 3. Dye injection into the aortic root homograft in Patient M. L. 1 year after operation. The absence of dye in the right ventricle (R.V.) when the homograft and pulmonary artery (P.A.) are well filled demonstrates competency of the homograft valve.
to demonstrate that a composite homograft which includes a segment of the ascending aorta and an aortic valve will function less well than either of its components used alone. The reports of Brock,4 Reichenbach and colleagues,17 and Angell and colleagues1 suggest a possible advantage in the use of fresh rather than freeze-dried homograft material, because degenerative changes in the homograft may be diminished and partial replacement of donor graft cells with host cells may be possible. Any criticism of the use of aortic root homografts for reconstruction of the right ventricular outflow tract must take into consideration alternative methods of treatment. Currently, the alternative to the use of aortic root homografts for the correction of truncus arteriosus is the use of a tube made of prosthetic or autologous material and containing a valve composed of prosthetic, homologous, or autologous material.7' s- "' A similar alternative would be required for the anatomic correction of transposition of the great arteries with ventricular septal defect and pulmonary stenosis in patients in whom construction of an intra-atrial baffle, closure of the ventricular septal defect, and relief of pulmonary obstruction6 were not possible. In a
small portion of patients with tetralogy of Fallot, total correction which provides adequate relief of right ventricular outflow tract obstruction produces severe pulmonary valvular insufficiency because of the absence of any functional pulmonic valve. 3 '"' 2 " Furthermore, in some patients with tetralogy, it is impossible for incisions in the right ventricular outflow tract to be extended from the right ventricle through the pulmonary valve annulus and into the pulmonary artery because of an anomalous coronary artery which traverses the outflow tract. Total correction by conventional methods is not possible in other patients with Fallot's malformation because of the absence of any connection between the right ventricle and pulmonary arteries (pulmonary atresia). 10 The alternative to the use of aortic root homografts in these patients is the acceptance of marked pulmonary incompetence or reconstruction with prosthetic, homograft, or autologous material alone or in various combinations. 7 - 8 ' 10 ' 12 Aortic root homografting compares favorably with these alternatives, which are all clearly less than ideal. Based upon these considerations and upon the experience reported above, continued use of aortic root homografts for reconstruction of the pulmonary artery, pulmonary valve, and out-
The Journal of
3 2 0 Brawley et al.
flow portion of the right ventricle appears to be indicated in certain patients. Summary Late results are presented in 8 patients who survived operation during which a homograft of the ascending aorta that included the aortic valve was used to reconstruct the outflow tract of the right ventricle. Two of the patients died 6 months after operation; the homograft valve was destroyed, presumably by bacteria, in 1 patient but appeared to be functional in the other. The remaining 6 patients have been followed from 17 to 59 months postoperatively. The clinical status of these 6 patients is good or excellent. Cardiac catheterizations, performed a year or more following operation in 5 of the patients, have demonstrated that the aortic root homografts are functioning well. The experience with this small group of patients suggests that aortic root homografts, when used for reconstruction of the right ventricular outflow tract, function satisfactorily for long periods of time in certain patients with congenital malformations of the heart.
REFERENCES
1 Angell, W. W., Stinson, E. B., Iben, A. B., and Shumway, N. E.: Multiple Valve Replacement With Fresh Aortic Homograft, J. THORAC. CARDIOVASC. SURG. 56: 323, 1968.
2 Beach, P. M., Bowman, F. O., Kaiser, G. A., and Malm, J. R.: Aortic Valve Replacement Using Frozen Irradiated Homografts: LongTerm Evaluation, Circulation. In press. 3 Bender, H. W., Jr., Haller, J. A., Jr., Brawley, R. K., Humphries, J. O., Neill, C. A., and Gott, V. L.: Experience in Repair of Tetralogy of Fallot Malformation in Adults, Ann. Thorac. Surg. 11: 508, 1971. 4 Brock, R. C : Long-Term Degenerative Changes in Aortic Segment Homografts With Particular Reference to Calcification, Thorax 23: 249, 1968. 5 Ching, E., DuShane, J. W., McGoon, D. C , and Danielson, G. K.: Total Correction of Cardiac Anomalies in Infancy Using Extracorporeal Circulation, J. THORAC. CARDIOVASC. SURG. 62: 117, 1971.
Thoracic and Cardiovascular Surgery
6 Daicoff, G. R., Schiebler, G. L., Elliott, L. P., Van Mierop, H. S., Bartley, T. D., Gessner, I. H., and Wheat, M. W., Jr.: Surgical Repair of Complete Transposition of the Great Arteries With Pulmonary Stenosis, Ann. Thorac. Surg. 7: 529, 1969. 7 Duran, C. M., Whitehead, R., and Gunning, A. J.: Implantation of Homologous and Heterologous Aortic Valves in Prosthetic Vascular Tubes, Thorax 24: 142, 1969. 8 Gott, V. L., Daggett, R. L., Koepke, D. E., Rowe, G. G., and Young, W. P.: Replacement of the Canine Pulmonary Valve and Pulmonary Artery With Graphite-Coated Valve Prosthesis, J. THORAC. CARDIOVASC. SURG. 44:
713, 1962. 9 Hawe, A., Rastelli, G. C , Ritter, D. G., DuShane, J. W., and McGoon, D. C : Management of the Right Ventricular Outflow Tract in Severe Tetralogy of Fallot, J. THORAC CARDIOVASC SURG. 60: 131, 1970.
10 Horiuchi, R., Abe, T., Okada, Y., Kuribayashi, R., Suzuki, Y., and Ishizawa, E.: Reconstruction of the Main Pulmonary Artery With a Valve-Bearing Tube Graft Made of Autologous Pericardium, J. THORAC CARDIOVASC SURG. 62: 793, 1971.
11 Knox, W. G., and Miller, R. E.: Long-Term Appraisal of Aortic and Arterial Homografts Implanted in Years 1954-1957, Ann. Surg. 172: 1076, 1970. 12 Marchand, P.: The Use of a Cusp-Bearing Homograft Patch to the Outflow Tract and Pulmonary Artery in Fallot's Tetralogy and Pulmonary Valvular Stenosis, Thorax 22: 497, 1967. 13 McGoon, D. C , Rastelli, G. C , and Ongley, P. A.: An Operation for the Correction of Truncus Arterious, J. A. M. A. 205: 59, 1968. 14 Mead, J. W., Linton, R. R., Darling, R. C , and Menendez, C. V.: Arterial Homografts, Arch. Surg. 93: 392, 1966. 15 Pacifico, A. D., Karp, R. B., and Kirklin, J. W.: A Comparison of Homografts and StarrEdwards Prostheses for Aortic Valve Replacement, Circulation. In press. 16 Rastelli, G. C , McGoon, D. C , and Wallace, R. B.: Anatomic Correction of Transposition of the Great Arteries With Ventricular Septal Defect and Subpulmonary Stenosis, J. THORAC CARDIOVASC SURG. 58: 545, 1969.
17 Reichenbach, D. D., Mohri, H., Sands, M., and Merendino, K. A.: Viability of Connective Tissue Cells Following Storage of Aortic Valve Leaflets,
J. THORAC. CARDIOVASC SURG. 62:
690, 1971. 18 Ross, D. N.: Biological Valves: Their Performance and Prospects, Circulation. In press.
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19 Ross, D. N., and Somerville, J.: Correction of Pulmonary Atresia With a Homograft Aortic Valve, Lancet 2: 1446, 1966. 20 Weldon, C. S., Rowe, R. D., and Gott, V. L.: Clinical Experience With the Use of Aortic Valve Homografts for Reconstruction of the
Pulmonary Artery, Pulmonary Valve, and Outflow Portion of the Right Ventricle, Circulation 37: 51, 1968 (Suppl. 2). 21 Weldon, C. S., and Cameron, J. L.: Correction of Persistent Truncus Arteriosus, J. Cardiovasc. Surg. 9: 2, 1968.