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Ann Thorac Surg 2005;80:832-838
© 2005 The Society of Thoracic Surgeons
a Cardiothoracic Centre, All India Institute of Medical Sciences, New Delhi, India
b Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India
Accepted for publication March 16, 2005.
* Address reprint requests to Dr Kumar, Department of Cardiothoracic and Vascular Surgery, Cardiothoracic Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029, India; (Email: asampath_kumar{at}hotmail.com).
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Abstract |
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METHODS: From January 1994 through September 2003, 154 patients with aortic valve disease (rheumatic = 118, nonrheumatic = 36), and a mean age of 28.8 ± 18.2 years, underwent aortic valve replacement with an aortic homograft by the scalloped subcoronary (n = 110) or root replacement (n = 38) technique, or as a valved homograft conduit (n = 6). Associated procedures included mitral valve repair (n=30), open mitral commissurotomy (n = 22), tricuspid valve repair (n = 8), coronary artery bypass grafting (n = 6), and atrial septal defect closure (n = 1).
RESULTS: Early mortality was 7.8% (12 patients). Mean follow-up was 62 ± 33.4 months (4 to 127 months; median, 68.5 months). One hundred and twenty-four survivors (87.3%) had no or trivial to mild aortic regurgitation. A total of six patients required reoperation for homograft dysfunction alone (n = 4), infective endocarditis (n = 1), or failure of mitral valve repair (n = 1). There were four late deaths. Actuarial and reoperation-free survival at the median follow-up were 92.2 ± 2.2% and 95.8 ± 1.9%, respectively. Freedom from significant aortic stenosis or regurgitation was 86.1 ± 3.2%.
CONCLUSIONS: Aortic valve replacement with an aortic homograft can be performed with acceptable early and late mortality and provides satisfactory midterm results. We did not note any difference in homograft dysfunction and reoperation with the use of either scalloped subcoronary or root replacement technique.
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Introduction |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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Homograft Preparation and Preservation
One hundred and forty-eight (96%) homografts were obtained from cadaveric donors 15 to 45 years of age. The hearts were obtained at autopsy within 24 hours of death using a sterile technique. The heart was rinsed in cold saline solution to remove blood and was then packed in 500 mL cold saline (4°C) in a sterile double bag and transported to our own valve bank adjacent to the operating room. Here the valves were dissected using an aseptic technique within a laminar flow hood. In the initial part of our experience, only antibiotic preservation was used. The following antibiotics were added to 1 liter of sterile filtered nutrient tissue culture medium (Hank’s solution): Cefoxitin 250 mg; lincomycin 120 mg; polymyxin B 100 mg; vancomycin 50 mg; and nystatin 1 million units. The N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffer was added to maintain a pH between 6.6 and 7.0. One hundred milliliters of sterile solution was added to each homograft (n = 28) for storage at 4°C. These antibiotic preserved homografts were used within 40 days. After dissection under sterile conditions, they were treated with an antibiotic solution for 48 hours at 4°C and used within 40 days (antibiotic preserved homografts, n = 28). In the latter part of our experience, these homografts were cryopreserved (n = 126, 81.2%). After 48 hours of incubation in the antibiotic solution, the homografts were removed from the antibiotic container and packaged with Rosewell Park Memorial Institute tissue culture medium no:1640 (RPMI 1640), 10% fetal calf serum, and 10% dimethyl sulfoxide. After sterile packaging, they were frozen at a rate of 1°C per minute in a Kryo 10 controlled rate freezer (Planer Products Ltd, Sunbury-on-Thames, Middlesex, UK) to a temperature of –40°C and then rapidly cooled to –150°C. They were then transferred for permanent storage in vapor phase liquid nitrogen between –150°C and –190°C in an XCL 500 vacuum insulated Dewar flask (Minnesota Valley Engineering Inc, Bloomington, MN). Six homografts were procured from cardiac transplant recipients; two of these were used immediately and the rest cryopreserved. These techniques have been described in detail in our prior publication [11].
Surgical Technique
Intraoperative TEE was performed in all patients to enable selection of an appropriate size homograft. The procedure was performed under standard moderately hypothermic (prior to 1996) or normothermic (after 1996) cardiopulmonary bypass. Antegrade direct ostial cold (4°C), hyperkalemic blood cardioplegia with topical ice slush was used for myocardial protection in all patients. Mitral valve repair was performed first if the patient had associated mitral valve disease. The HAVR was performed only if the mitral valve repair was satisfactory and the aortic valve was unsuitable for repair. No additional procedure was performed for correction of AF.
In 110 (71.4%) patients, the scalloped subcoronary implantation technique described by Ross [12] was used. In 38 (24.7%), the root replacement technique [13] was used. In six (3.9%) patients, both the aortic valve and the ascending aorta were replaced using a valved homograft conduit as described by us earlier [14]. Associated procedures included mitral valve repair (n = 30), open mitral commissurotomy (n = 22), tricuspid valve repair (n = 8), coronary artery bypass grafting (n = 6), and atrial septal defect closure (n = 1). After discontinuation of cardiopulmonary bypass, TEE was performed in all patients to confirm normal homograft function and for assessment of associated procedures.
No anticoagulants or antiplatelet drugs were prescribed. Long acting benzathine penicillin was prescribed every 3 weeks to all patients less than 45 years of age with rheumatic heart disease. All patients received Itraconazole for 6 weeks after operation as a prophylaxis against fungal endocarditis.
Follow-Up
Prior to discharge from the hospital, TEE was performed in all patients. All survivors were seen in the outpatient clinic after one month, three months, six months, and then at yearly intervals, and underwent clinical examination, chest radiographs, and detailed echocardiography. Echocardiographic assessment consisted of serial evaluation of homograft function (regurgitation, stenosis, dilatation, calcification, vegetations), assessment of mitral valve repair, and measurement of left ventricular end-systolic and end-diastolic diameter, and ejection fraction. The period between April 2004 and September 2004 was the closing interval when 137 of the 142 survivors were last seen and underwent echocardiography. Their last follow-up during this period was taken for reporting the results.
Aortic regurgitation (AR) was assessed on a scale of +1 to +4 according to published criteria [15]. The AR with grade +1 was considered of mild severity. Mean gradient across the aortic valve was used to define the severity of AS (mild, 
25 mm Hg; moderate, 25–50 mm Hg; severe, > 50 mm Hg). In the absence of a mean gradient, peak gradients 50 mm Hg or greater and 75 mm Hg or greater across the aortic valve were considered as moderate and severe AS (Table 3)
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Results |
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Early Homograft Function
In all patients, intraoperative TEE revealed trivial or no aortic regurgitation. Transthoracic echocardiography prior to discharge from the hospital showed mild AR in six patients and mild AS in two patients.
Late Outcome
The follow-up data (96% complete) ranged from 4 to127 months (mean, 62 ± 33.4 months; median, 68.5 months) and totaled 738.4 patient years. Among survivors, 5 (3.5%) patients were followed up for 10 or more years, 51 (35.9%) were followed for 7 or more years, 89 (62.7%) for more than 5 years, 123 (86.6%) for more than 3 years, and 131 (92.2%) for more than 2 years.
Thromboembolism
There were no thromboembolic complications in the survivors.
Hemolysis
Two patients had significant hemolysis (0.3 events per 100 patient years). This was associated with mild mitral regurgitation (MR) in one and severe MR in another patient. In the first patient, it subsided gradually. The second patient underwent mitral valve rerepair 26 months later and recovered uneventfully.
Infective Endocarditis
Five patients developed infective endocarditis (0.67 events per 100 patient years). This was due to Aspergillus in three and Staphylococcus aureus in two patients. One patient each with bacterial and fungal endocarditis died within a month of initial operation without reoperation. The other patient with bacterial endocarditis recovered after antibiotic therapy and the other two patients with fungal endocarditis died three and five months later; one of these died after reoperation.
Late Homograft Function
Serial TEE showed no significant aortic regurgitation in 124 (87.3%, none in 90 and mild in 34) survivors. Eighteen patients had significant aortic regurgitation (2.4 events per 100 patient years). Moderate (n = 12, 8.5%) to severe (n = 6, 4.2%) aortic regurgitation was noted in 18 (13.3%) of the 142 survivors at a mean follow-up of 32 ± 20 months after operation. The probability of development of AR was independent of the etiology, technique of implantation, and the method of valve preservation. One patient with severe AR was lost to follow-up and the other five underwent reoperation. In four of these, prosthetic valves were implanted on patient request and all recovered uneventfully. The fifth patient had AR secondary to fungal endocarditis. She died after redo-HAVR. The remaining 12 patients with moderate AR are in NYHA class I without evidence of left ventricular dysfunction and are being closely followed up. Two of these also have moderate AS with mean gradients of 35 mm Hg and 40 mm Hg, respectively. Besides these, four patients have mild AS (mean gradients less than 25 mm Hg) and are being followed up. At median follow-up, freedom from homograft dysfunction was 86.1 ± 3.2% (95% confidence interval [CI] 79.8 to 92.4); at 10 years it was 84.9 ± 3.31% (95% CI 78.4 to 91.4) (Fig 1).
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Three reoperations each were required in patients undergoing HAVR with the scalloped subcoronary or root replacement technique. In patients undergoing reoperation other than for endocarditis, the geometry of the aortic sinuses was maintained. The homograft cusps showed thickening and failure of coaptation. The aortic root was not dilated in any patient. Only one 29-year-old patient who underwent HAVR with the root replacement technique 65 months earlier had evidence of homograft calcification. At the median follow-up period, freedom from reoperation was 95.8 ± 1.9% (95% CI 92.1 to 99.5) and at 10 years it was 94.3 ± 2.3 % (95% CI 89.8 to 98.8) (Fig 2).
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Late Deaths and Survival
There were four late deaths (0.5 events per 100 patient years). Two of these were due to infective endocarditis as discussed above and two were due to progressive left ventricular dysfunction with normal valve function. At a median follow-up of 68.5 months, the actuarial survival was 92.2 ± 2.2% (95% CI 87.9 to 96.5) and was similar at 10 years (Fig 3).
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Comment |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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Operative techniques for HAVR were described by Barratt-Boyes [19], Ross [20], and Paneth and O’Brien [21]. Their initial popularity was due to the low mortality and good intermediate-term results. However the problems of donor supply, storage, and limited durability of chemically treated and antibiotic-preserved allografts limited their use [8]. With the advent of cryopreservation and adherence to strict protocols of valve collection, disinfection and storage, there was a resurgence in their use and long-term results in this subset of patients were available [1–4]. In our own surgical practice, their use in the aortic position increased after our disappointing results with the pulmonary autograft in young rheumatics with associated mitral valve disease [10]. We now consider all suitable young rheumatic patients (as detailed above) as ideal candidates for this procedure, particularly if the mitral valve disease is amenable to repair.
There is debate about the best technique for HAVR [22–27]. The scalloped subcoronary technique carries the advantage of an easier reoperation in the event of structural deterioration as compared to the root replacement technique [23]. However, the technique is difficult, has a definite learning curve, and leads to a higher incidence of early reoperations if the exact geometry is not maintained. Elkins and colleagues advocate the aortic root inclusion whereas O’Brien and colleagues favor the root replacement technique [3, 23, 25]. The root replacement technique is easier to perform but reoperations after this technique are difficult. Aortic root inclusion technique may be associated with increased gradients across the homograft and distortion of coronary anastomosis because of a blood filling space between the homograft and the native aortic wall. Currently we prefer the scalloped subcoronary technique in younger patients in whom reoperation is anticipated earlier than the older patients (> 60 years). However, we would prefer the root replacement technique in young patients requiring root and ascending aorta replacement [14]. On comparison of the two techniques in our patients, we found no difference in the early and late mortality and the early and late reoperation rate.
Reoperation for structural deterioration has been a concern after HAVR. In our patients, the freedom from reoperation was 94.3 ± 2.3% at 10 years. This compares favorably with the 92% freedom from reoperation reported by Doty and colleagues [2], and O’Brien and colleagues [3], and 86% freedom at 8 years reported by Kirklin and colleagues [26]. The longest follow-up of up to 15 years is by O’Brien and colleagues [3] and they report a freedom from structural deterioration of 80% at 15 years. This is also comparable with the 85% freedom from reoperation noted with the use of the commercially available stented bovine Carpentier-Edwards pericardial bioprosthesis [18]. However, the hemodynamics provided by the homografts are much better than the bioprosthesis; with the use of the latter, gradients more than 20 mm Hg are common even at operation [4]. Use of homografts is especially advantageous in the younger age group not only to avoid anticoagulation, but also because excellent hemodynamics favor a more vigorous functional status in young patients [28].
Another advantage of HAVR is their durability in the setting of native or prosthetic valve endocarditis. Riberi and colleagues [5] and Niwaya and colleagues [6] have reported excellent results with the use of homografts in these patients, with no recurrent infection.
The 10-year actuarial survival has been good after HAVR. In a recent report of nearly 400 patients [1] it was 86.2% at 10 years; in Lund and colleagues’ series [29] it was 84% at 10 years, and in O’Brien’s series [3] it was 87%. This is much higher than the 53% survival at 10 years reported with the use of mechanical valves [30] and is mainly due to the avoidance of anticoagulation and the reduced risk of endocarditis.
The potential limiting factor for routine use of HAVR is the limited donor supply, difficulties of establishing valve banks [11], and mastering the techniques of HAVR. However, once the valve banks are established and the appropriate techniques mastered, the procedure is very cost effective.
Aortic valve replacement with the aortic homograft can be performed with low early and late mortality and provides satisfactory midterm results. We did not note any difference in homograft dysfunction and reoperation with the use of either scalloped subcoronary or root replacement techniques.
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References |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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