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Interact CardioVasc Thorac Surg 2009;9:775-779. doi:10.1510/icvts.2008.200097 © 2009 European Association of Cardio-Thoracic Surgery
Reconstruction of atrioventricular valves with photo-oxidized bovine pericardiumDepartment of Cardiac Surgery, Katholieke Universiteit Leuven, Herestraat 49, B-3000 Leuven, Belgium Received 4 December 2008; received in revised form 22 July 2009; accepted 23 July 2009
*Corresponding author. Tel.: +32 16 344260; fax: +32 16 344616.
Repair of complex valve pathological processes often requires the use of leaflet tissue or pericardium. The use of bovine photo-oxidized pericardium may be an alternative, a tissue less prone to calcification. The aim of this study is to evaluate the use of photo-oxidized bovine pericardial tissue in the reconstruction of atrioventricular valves in humans. Between July 2001 and September 2006, 21 patients with complex valve pathology underwent a reconstruction with photo-oxidized pericardium. The pericardial patch was used for the reconstruction of a tricuspid valve leaflet in two patients, the reconstruction of a mitral valve leaflet in six patients, the reconstruction of the tricuspid annulus in one patient and the reconstruction of the mitral annulus in 12 patients. The follow-up ranged from 13.9 to 43.2 months. There were five perioperative deaths. Four patients developed failure of the reconstruction, in one patient there was thinning and perforation of the pericardial patch without signs of infection or abrasion. The other patients were free from thromboembolism, endocarditis, hemorrhagic complications or echocardiographic signs of failure of the reconstruction. Photo-oxidized bovine pericardium is a versatile material for complex reconstruction of the atrioventricular valvular structures. Its durability should, however, be investigated in comparison with alternative tissues in a randomized trial.
Key Words: Heart valve; Reconstruction; Photo-oxidation; Pericardium
Valvuloplasty is an established therapeutic modality for the surgical treatment of mitral or tricuspid insufficiency [1, 2]. However, an occasional problem for repair of complex valve pathological processes, such as extensive calcification of the annulus and infective endocarditis, is the lack of sufficient leaflet tissue or autologous pericardium. The use of bovine photo-oxidized pericardium in these occasions might be an alternative. Glutaraldehyde is the most frequently used chemical preservative for bioprosthetic tissue. Glutaraldehyde cross-linking potentiates mineral deposition, leading to structural degeneration of the tissue [3–6]. An alternative for this treatment is dye-mediated photo-oxidation, which relies on methylene blue and light to create new cross-links in collagenous substrate [7, 8]. Previously, photo-oxidation was used to study protein function through amino acid alterations [9]. The discovery that photo-oxidation could stabilize a protein solution [10] led to the development of this technology for biomedical purposes. The process was found suitable for the preparation of biological tissues for long-term implantation in humans. The required properties are solvent and enzymatic stability, stability to chemical degradation, low calcification potential, low immunogenicity, biocompatibility, and biostability [11–13]. The only human results so far are those reported by Schoen [14] who assessed the pathologic findings in explanted valves fabricated from photo-oxidized bovine pericardium. His principal findings were that the cause of tissue failure by perforation was in all cases design-related and that the microscopic tissue quality remained generally sound. This report describes our experience with reconstruction of atrioventricular valves with photo-oxidized bovine pericardium.
Between July 2001 and September 2006, 21 patients aged 60±16 years (range 27 to 80 years) underwent a reconstruction of the atrioventricular valve with photo-oxidized pericardium, in the University Hospitals of the Katholieke Universiteit Leuven. Table 1 summarizes the clinical profile of these patients [15]. The preoperative evaluation of the cardiac function was often incomplete seeing the emergency of operation in several patients. As shown, most of the patients were in New York Heart Association (NYHA) functional class IV when operated on, and three of them were in septic or cardiogenic shock or both. Three patients had at least one cardiac operation in history: one had five mitral valve replacements (MVR), one had aortic valve replacement (AVR) and one had MVR and AVR. Three underwent percutaneous coronary interventions, two of them within three weeks before the valve operation.
Table 2 shows the operative data. The indication for operation was infective endocarditis in 15 patients, extensive calcification in four patients, a papillary fibroelastoma in one patient and a paravalvular leak after five previous valve replacements in one patient. The pericardial patch was used for the reconstruction of a tricuspid valve leaflet in two patients, the reconstruction of a mitral valve leaflet in six patients, the reconstruction of the tricuspid annulus in one patient and 12 patients underwent a reconstruction of the mitral annulus with implantation of a prosthetic valve. An annuloplasty ring was used in all other patients. In addition to the reconstruction of one of the atrioventricular valves, 10 of the 21 patients had at least one more cardiac intervention during the same operation. When the patch was used for annular reconstruction, it was inserted with running 4/0 polypropylene sutures. For partial replacement of the leaflet of the atrioventricular valve, it was inserted with running 5/0 polypropylene.
For the follow-up, every hospitalization and consultation letter was evaluated for symptoms and clinical signs of cardiac failure, thromboembolic events, bleeding, infective endocarditis and valve failure. The patients and general practitioners were also interviewed by telephone contact using a standardized questionnaire. The pre- and postoperative echocardiographic parameters were evaluated. The following parameters were studied: survival, hospital mortality, late mortality, cause of death, postoperative morbidity and NYHA functional class. Hospital mortality is defined as the number of patients who died during the hospital stay after the cardiac operation.
The follow-up ranged from 13.9 to 43.2 months (mean follow-up 28.6±10.4 months). No patient was lost to follow-up. Table 3 shows the use of the patches and fate of each patient. There were five perioperative deaths, so a hospital mortality rate of 24%. The reason for surgery was endocarditis in all these patients, four of them underwent a complex combined procedure. One patient died during reintervention from a rupture of the posterior wall of the left ventricle after reconstruction of the posterior annulus with a pericardial patch and implantation of a prosthetic valve. Two patients died of multiple organ failure 10 and 16 weeks after surgery. The two other patients died of intractable septic shock two days, and 22 weeks, respectively, after the intervention.
The median stay at intensive care was 6.5 days (range 1–124 days), the median duration of hospitalization was 50.5 days (range 10–124 days). Postoperative complications were frequent. One patient needed reintervention for a ventricle rupture. Two patients needed reexploration for bleeding. One patient developed acute leg ischemia, treated by surgical thrombectomy. Two patients were resuscitated successfully, one because of asphyxia as a result of a thrombus in the trachea caused by a throat bleeding and another because of sudden cardiac collapse. Eight patients needed hemodialysis, two of them chronically, one of them was already in chronic renal failure preoperatively. Two patients needed implantation of a pacemaker for a third degree atrio-ventricular block. Ten patients had a postoperative episode of atrial fibrillation or flutter, and in four of them this was also present preoperatively. Five of them were reconverted successfully. One patient had percutaneous ablation of an intra-atrial reentry tachycardy. Three patients died after hospital discharge. One 80-year-old patient died 19 weeks after reconstruction of the annulus. Four weeks after the operation he developed a paravalvular leak with clinical and echocardiographic signs of recurrent endocarditis. Reoperation was deemed impossible and the patient went home for palliative care. Two other patients died – both around 24 months postoperatively. One of them died as a consequence of a resistant sepsis, without clinical or echocardiographic signs of failure of the reconstruction. The other one that had received a partial leaflet replacement by the patch died after reoperation for massive mitral valve regurgitation. This massive mitral regurgitation first appeared 22 months after his mitral leaflet reconstruction. During the reintervention, a perforation of the pericardial patch was seen, with the parts of the pericardial patch around the perforation very thin and translucent. No sutures or other foreign material were present in the neighborhood of the perforation, and no acute or healed vegetations were seen (Fig. 1). Histology of this valve showed no inflammation or cellular infiltration of the patch, but progressive thinning of the patch. The perforation was on all sides surrounded by patch material, excluding suture dehiscence.
After discharge no thromboembolism, new endocarditis or a major hemorrhagic complication was encountered. At the most recent follow-up (mean 29 months, range 15–43 months) five patients (38%) are in NYHA functional class I, 6 (46%) in class II and 2 (15%) in class III. Echocardiographic studies were performed in all patients, except two who died shortly after operation. These were done preoperatively, before hospital discharge, 6 months postoperatively, and then every 12 months after operation. In the group who underwent a leaflet reconstruction, one patient developed a significant valve insufficiency, grade 3/4, 22 months postoperative. This is the patient who died after reoperation. All other patients who underwent a leaflet reconstruction had a good echocardiographic result of the reconstruction, with only slight valvular insufficiency. Two patients who underwent a reconstruction of the annulus developed a significant paravalvular leak (grade 3 or 4/4), one 4 weeks after intervention as a consequence of recurrent endocarditis. The other patient developed a leak 16 months after annulus reconstruction. This is a patient who underwent an implantation of a prosthetic mitral valve for the sixth time in the treatment of a paravalvular leak. In both cases, the paravalvular leak appeared at the site of the annulus reconstruction. Actuarial survival and freedom from failure of the reconstruction are depicted in Figs. 2 and 3.
Repair of severe atrioventricular valve disease caused by complex valve pathological processes such as destructive infective endocarditis, extensive calcification of the annulus, large perforations, heavy myxomatous degeneration, and rheumatic carditis is occasionally limited by the remaining amount of unaffected tissue after extensive tissue debridement [1, 2]. The use of pericardium is attractive in these circumstances. Its ready availability, easy handling and pliability make it an obvious choice when a defect must be corrected. Glutaraldehyde pretreated autologous pericardium is the material of choice [1, 2]. The use of fresh pericardium has been discouraged because of progressive contracture, thicking fibrosis, loss of pliability, early degeneration, and endocarditis. In redo operations, emergency situations, or preoperative unexpected findings it is sometimes not feasible to prepare sufficient autologous pericardium in time. An alternative is the use of glutaraldehyde fixed bovine pericardium [1]. Glutaraldehyde treatment of tissue limits the host response and increases the tissue durability by cross-linking collagen residues, though the price paid for this stability is increased mineralization potential and stiffness [3–6]. Photo-oxidation treatment increases tissue durability and induces significantly less propensity for mineralization than does glutaraldehyde treatment [11–13]. In an assessment of 10 photo-oxidized pericardial aortic valves [14], explanted for regurgitation after 8–23 months' function, the cause of failure was presumed to be related to the design of the prosthetic valve. But, microscopically, tissue quality remained generally sound. In our study, the reconstruction failed in four patients of the 21. One patient who underwent annular reconstruction developed rupture of the posterior wall of the ventricle. Another patient with patch reconstruction of the annulus developed recurrent infectious endocarditis four weeks postoperative with progressive valve dehiscence starting from the reconstructed site. The patient who underwent his sixth operation for non-ingrowing mitral valve with annulus destruction that was reconstructed, had a recurrent paravalvular leak 16 months after intervention at the site of the patch. Presumably, these failures of the reconstruction were unrelated to the patch material. One patient, where the pericardial patch was used to close a defect in the anterior leaflet after excision of a vegetation, developed valve insufficiency 22 months postoperative. During reintervention, a perforation of the pericardial patch was visible a few mm away from the suture, so in the middle of the patch. Pathological investigation did not reveal signs of acute or healed endocarditis or abrasion of the pericardial patch, and with thinning of the material around the perforation. We, therefore, consider this case suggestive for an intrinsic failure of the photo-oxidized bovine pericardial patch. All other patients have a clinical and echocardiographic good result of the reconstruction without any sign of failure, this up to a follow-up of 43 months, which is an acceptable outcome with this difficult patient cohort. Photo-oxidized bovine pericardium is a versatile material that might have its place, where the lack of sufficient leaflet tissue or autologous pericardium is the limiting factor for valvuloplasty. In our study, one patient developed a perforation of the pericardial patch that is suggestive of tissue failure. To define its correct place in the surgical armamentarium, a randomized controlled trial in comparison with other tissue material as control group is necessary. In the meantime, careful follow-up of these patients is necessary, as always after this kind of complex reconstruction.
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Abstract
1. Introduction
