Bovine pericardium for correction of congenital heart defects

Role of Pericardial Patch in Neurosurgery: Institutional Experience

INTRODUCTION

Dural closure is an important part of neurosurgery, failure which may lead to wound infection, pseudomeningoceles, meningitis, severe morbidity to a patient, and even mortality. In cases where primary dura closure is not possible, a bovine pericardial patch is a good alternative with the benefits of suturability and the ability to provide watertight closure, hence preventing Cerebrospinal Fluid (CSF) leak. The present study demonstrates the use of the bovine pericardial patch in both cranial and spinal disorders for dural closure as well as for transposition technique in microvascular decompression.

OBJECTIVES

The aim of our study is to understand the advantages and feasibility of a bovine pericardial patch in various neurosurgical procedures.

MATERIAL METHODS

Fifty-one patients were analyzed prospectively and followed up in which glutaraldehyde-free bovine pericardial patch was used in various cranial and spinal disorders.

RESULTS

The most common indications where a bovine pericardial patch was used, in decreasing order of frequency, were meningioma excision surgery (47%), followed by Chiari malformation operated for foramen magnum decompression (17.6%), meningomyelocele (7.8%), spinal dural defects (7.8%), trigeminal neuralgia (5.8%), traumatic decompression with lax duraplasty (4%), glioma (4%), encephalocele (4%), and skull base defects (2%). Two patients had complications, one with CSF leak and the other had superficial wound infection, which were managed appropriately.

CONCLUSIONS

The use of a bovine pericardial patch as a dural substitute in various cranial and spinal disorders is feasible with good outcomes, and it can be considered an ideal dural substitute.

Patch Materials for Pulmonary Artery Arterioplasty and Right Ventricular Outflow Tract Augmentation: A Review

Patch augmentation of the right ventricular outflow tract (RVOT) and pulmonary artery (PA) arterioplasty are relatively common procedures in the surgical treatment of patients with congenital heart disease. To date, several patch materials have been applied with no agreed upon clinical standard. Each patch type has unique performance characteristics, cost, and availability. There are limited data describing the various advantages and disadvantages of different patch materials. We performed a review of studies describing the clinical performance of various RVOT and PA patch materials and found a limited but growing body of literature. Short-term clinical performance has been reported for a multitude of patch types, but comparisons are limited by inconsistent study design and scarce histologic data. Standard clinical criteria for assessment of patch efficacy and criteria for intervention need to be applied across patch types. The field is progressing with improvements in outcomes due to newer patch technologies focused on reducing antigenicity and promoting neotissue formation which may have the ability to grow, remodel, and repair.

Performance of the ADAPT-Treated CardioCel® Scaffold in Pediatric Patients With Congenital Cardiac Anomalies: Medium to Long-Term Outcomes

Background: A Phase II Clinical Trial reviewed the performance (morbidity and calcification) of the tissue-engineered ADAPT® bovine pericardial scaffold (CardioCel®) in pediatric patients (n = 30) with congenital cardiac defects. In that study, CardioCel® demonstrated no graft-related morbidity and mortality in 25 patients, over 12 months. Five patients died due to non-graft-related events. Echocardiography revealed hemodynamically stable repairs with no calcification of the scaffold. Magnetic resonance imaging (MRI) at 12 months in 10 patients confirmed the absence of calcification. These patients were followed up for further up to 10 years. We present the results of this retrospective review of these patients that were followed for further medium to long-term (median 7.2 years, 25%: 3.6 years 75%: 9.25 years) postoperatively in these patients. Methods: Between April 2008 and September 2009, CardioCel® was implanted in 30 patients with congenital cardiac defects. Efficacy measures included graft-related mortality, morbidity and haemodynamic abnormalities. Calcification was assessed by standard 2D-M mode echocardiography and MRI at 12 months. Medium to long-term assessment included routine clinical assessments and echocardiography. Results: Median age at surgery was 18 months (27 days-13 years). Twenty-five patients (142 patient years) were followed for up to 10 years. The 10-year survival rate is estimated as 86.9% (95% CI 71.4-100.0%) over the entire follow-up period. One patient was lost to follow-up. No graft-related mortality was encountered up to a median follow-up of 7.2 years. Two patients died (pacemaker complications >5 years and arrhythmia >7 years postoperatively). No graft failure, thromboembolic events, infections or device-related reinterventions were recorded. Non-significant residual leaks occurred in 3 patients. Echocardiography demonstrated the absence of calcification in all implants. Conclusion: The tissue-engineered ADAPT® bovine pericardial scaffold demonstrated excellent medium to long-term performance (up to 10 years) when used as a scaffold for repair of congenital cardiac defects in children. Durability, acellularity, biostability and non-calcifying potential of CardioCel® makes it a very attractive tissue for congenital cardiac repair procedures.

Bioengineered tissue solutions for repair, correction and reconstruction in cardiovascular surgery

The treatment of cardiac alterations is still nowadays a dramatic issue in the cardiosurgical practice. Synthetic materials applied in this surgery have failed in their long-term therapeutic efficacy due to low biocompatibility and compliance, especially when used in contractile sites. In order to overcome these treatment pitfalls, novel solutions have been developed based on biological tissues. Patches in pericardium, small intestinal submucosa, as well as engineered tissues of myocardium, heart valves and blood vessels have undergone a large preclinical investigation in regenerative medicine studies. Clinical translation has been started or reached by several of these new bioengineered treatment alternatives. This review will describe the preclinical and clinical experiences realized so far with the application of biological tissues in cardiovascular surgery. It will depict the progressive steps realized in the evolution of this research, as well as it will point out the challenges yet to face in order to generate the ideal biomaterial for cardiovascular repair, corrective and reconstructive surgery.

Patch materials for right ventricular outflow reconstruction: past, present, and future

In this review, we discuss various patch materials used for reconstruction of the right ventricular outflow tract. Their relative merits and demerits are discussed. Traditional patches and their results are detailed along with a brief description of newer developments in the field.

Application of the CardioCel bovine pericardial patch - a preliminary report

Introduction

Animal pericardial patches are widely used in adult and pediatric cardiac surgery. A search is ongoing for a new material with optimal surgical properties that will reduce intraoperative bleeding and the occurrence of restenosis, calcification, and pseudoaneurysms in long-term observation. One product of interest is the CardioCel bovine pericardial patch.

Aim

Evaluation of the short-term results of CardioCel bovine pericardial patch implantation during pediatric cardiac surgery.

Material and methods

The study included 8 patients who underwent surgical correction of congenital cardiac defects between January 2015 and February 2016. Pericardial patches were used to repair supravalvular aortic stenosis and reconstruct the aortic arch and pulmonary arteries. The age of the patients ranged from 10 days to 14 years.

Results

There were no hospital deaths. The new material exhibited satisfactory durability and elasticity during surgery, facilitating optimal adaptation of the patch to the patient's tissues. No significant bleeding was reported from the suture site. The median duration of follow-up was 58 days. During the follow-up, there were no symptoms of pseudoaneurysm formation, patch thickening, or calcification in the areas where the pericardial patches were implanted. No clinical or laboratory symptoms of infection were observed in locations where the new material was applied.

Conclusions

Satisfactory surgical properties of the patch were observed intraoperatively. Positive results using the new pericardial patch were obtained in short-term follow-up.

Short- and mid-term results of xenograft-bovine pericardial patch in the repair of intracardiac defects: final results of a single-centre study

INTRODUCTION

A variety of patch materials have been used in the repair of intracardiac defects. We evaluated the short- and mid-term clinical and echocardiography results of glutaraldehyde-preserved bovine pericardium patches used to repair intracardiac defects in our clinic.

METHODS AND RESULTS

This study examines the short- (up to 30 days post-operatively) and mid-term (up to 24 months post-operatively) results of 533 patients with intracardiac defects who underwent surgical correction with glutaraldehyde-preserved bovine pericardium patches between 2004 and 2010 at a university clinic. Short- and mid-term post-operative echocardiographic studies showed no evidence of calcification, thrombus, or aneurysmal dilatation on the patch. Vegetation developed in two (0.37%) of the 533 patients.

CONCLUSION

These results that have been obtained from a group of large number of patients imply that the glutaraldehyde-preserved bovine pericardium patches may be preferable in the closure of cardiac defects because of their low complication rates and ease of use.

Nanofibers coated on acellular tissue-engineered bovine pericardium supports differentiation of mesenchymal stem cells into endothelial cells for tissue engineering

Aim: This study aimed to develop biodegradable, polymer-based nanofibers coated on acellular tissue-engineered bovine pericardium (ATEBP) for cell interfaces, enabling more exquisite functionality, such as mesenchymal stem cell (MSC) adhesion, proliferation and differentiation into endothelial cells for tissue engineering. Materials & methods: ATEBP coated with nanofibers of poly(L-lactic acid)-co-poly(ε-caprolactone) (PLACL) and a blend of PLACL and gelatin were analyzed for human bone marrow-derived MSC adhesion, proliferation and differentiation into endothelial cells. Results: The cell culture-based approach showed an increase in human bone marrow-derived MSC adhesion, proliferation and differentiation into endothelial cells on ATEBP coated with PLACL/gelatin nanofibers compared with ATEBP and PLACL nanofibers coated on ATEBP. Conclusion: ATEBP coated with PLACL/gelatin nanofibrous scaffolds, along with human bone marrow-derived MSCs differentiated into endothelial cells, might improve the scaffolds’ functionality for tissue engineering.

Original submitted 5 July 2012; Revised submitted 24 January 2013

Bovine pericardium patch wrapping intestinal anastomosis improves healing process and prevents leakage in a pig model

Failure of intestinal anastomosis is a major complication following abdominal surgery. Biological materials have been introduced as reinforcement of abdominal wall hernia in contaminated setting. An innovative application of biological patch is its use as reinforcement of gastrointestinal anastomosis. The aim of study was to verify whether the bovine pericardium patch improves the healing of anastomosis, when in vivo wrapping the suture line of pig intestinal anastomosis, avoiding leakage in the event of deliberately incomplete suture. Forty-three pigs were randomly divided: Group 1 (control, n = 14): hand-sewn ileo-ileal and colo-colic anastomosis; Group 2 (n = 14): standard anastomosis wrapped by pericardium bovine patch; Group 3 (n = 1) and 4 (n = 14): one suture was deliberately incomplete and also wrapped by patch in the last one. Intraoperative evaluation, histological, biochemical, tensiometric and electrophysiological studies of intestinal specimens were performed at 48 h, 7 and 90 days after. In groups 2 and 4, no leak, stenosis, abscess, peritonitis, mesh displacement or shrinkage were found and adhesion rate decreased compared to control. Biochemical studies showed mitochondrial function improvement in colic wrapped anastomosis. Tensiometric evaluations suggested that the patch preserves the colic contractility similar to the controls. Electrophysiological results demonstrated that the patch also improves the mucosal function restoring almost normal transport properties. Use of pericardium bovine patch as reinforcement of intestinal anastomosis is safe and effective, significantly improving the healing process. Data of prevention of acute peritonitis and leakage in cases of iatrogenic perforation of anastomoses, covered with patch, is unpublished.

Evaluation of a tissue-engineered bovine pericardial patch in paediatric patients with congenital cardiac anomalies: initial experience with the ADAPT-treated CardioCel(R) patch

OBJECTIVES

This study evaluated the safety, efficacy and clinical performance of the tissue-engineered ADAPT® bovine pericardial patch (ABPP) in paediatric patients with a range of congenital cardiac anomalies.

METHODS

In this single-centre, prospective, non-randomized clinical study, paediatric patients underwent surgery for insertion of the ABPP. Primary efficacy measures included early (<30 day) morbidity; incidence of device-related complications; haemodynamic performance derived from echocardiography assessment at 6- and 12-month follow-up and magnetic resonance imaging findings in 10 randomly selected patients at 12 months. Secondary measures included device-handling characteristics; shape and sizing characteristics and perioperative implant complications. The Aristotle complexity scoring system was used to score the complexity level of all surgical procedures. Patients completing the 12-month study were eligible to enter a long-term evaluation study.

RESULTS

Between April 2008 and September 2009, the ABPP was used in 30 paediatric patients. In the 30-day postoperative period, no graft-related morbidity was observed. In total, there were 5 deaths (2 in the 30-day postoperative period and 3 within the first 6 postoperative months). All deaths were deemed due to comorbid non-graft-related events. Echocardiography assessment at 6 and 12 months revealed intact anatomical and haemodynamically stable repairs without any visible calcification of the patch. Magnetic resonance imaging assessment in 10 patients at 12 months revealed no signs of calcification. Fisher's exact test demonstrated that patients undergoing more complex, higher risk surgical repairs (Aristotle complexity score >8) were significantly more likely to die (P = 0.0055, 58% survival compared with 100% survival for less complex surgical repairs). In 19 patients, echocardiographic data were available at 18-36 months with no evidence of device calcification, infection, thromboembolic events or device failure.

CONCLUSIONS

This study demonstrates the safety and efficacy of this engineered bovine pericardial patch as a cardiovascular substitute for surgical repair of both simple and more complex congenital cardiac defects.

Intermediate-term outcome of carotid endarterectomy with bovine pericardial patch closure compared with Dacron patch and primary closure

OBJECTIVE

Multiple studies have established that patch angioplasty following carotid endarterectomy (CEA) reduces the risk of subsequent stroke and restenosis compared with primary closure. Previous reports have also demonstrated bovine pericardium to be associated with similar rates of postoperative complications and restenosis compared with other patch materials. Due to favorable handling and sonographic properties, bovine pericardium has become increasingly popular as a patch option in recent years. However, the intermediate- and long-term performance of this material remains incompletely defined. Through a retrospective analysis of our carotid endarterectomy experience, we sought to compare the bleeding, infection, and pseudoaneurysm rates with bovine pericardium patch closure to those with Dacron patch and primary closure. In this study, 1331 primary carotid endarterectomies performed in our institution between 1996 and 2008 were grouped according to the method of arteriotomy closure: primary closure (PC) (216, 16.3%), Dacron patch angioplasty (DPA) (642, 48.2%), and bovine pericardial patch angioplasty (BPA) (457, 34.3%). Demographic variable and postoperative outcome measures collected real-time via a designated database manager were assessed by univariate and multivariate analysis.

RESULTS

Mean follow-up for the entire cohort was 46.1 months. There were no statistically significant differences in rates of postoperative wound infection, hematoma, pseudoaneurysm formation, or 30-day stroke or 30-day mortality among the three groups. Combined 30-day stroke and death was significantly lower in the PC cohort (0.5% vs 2.3% DPA vs 2.4% BPA; P = .94, BPA vs DPA; P = .001, BPA vs PC; P = .001, DPA vs PC), while 5-year restenosis after both DPA (2.0% ± 0.6%) and BPA (1.1% ± 0.6%) was significantly lower compared with PC (5.2% ± 1.6%) (P = .03, DPA vs PC; P = .008, BPA vs PC; P = .14, BPA vs DPA). Five-year survival following BPA (77.9% ± 3.6%) was significantly improved compared with PC (66.9% ± 3.5%) and DPA (60.8% ± 2.1%) in univariate analysis (P = .24, DPA vs PC; P = .01, BPA vs PC; P = .03, BPA vs DPA), with statin use (P = .004) and male gender (P = .05) being positive predictors of enhanced survival on multivariate analysis.

CONCLUSIONS

This single-institution, retrospective review represents the largest reported experience with BPA after CEA to date and is the only report comparing outcomes after BPA to PC or to DPA. Our experience further demonstrates that patch angioplasty is protective against restenosis after CEA compared with PC. Equivalent rates of perioperative bleeding, infection, and pseudoaneurysm formation were seen with each closure strategy in this study.

The development of tissue-engineered grafts for reconstructive cardiothoracic surgical applications

Surgical correction of congenital heart defects often requires the use of valves, patches, or conduits to establish anatomic continuity. Homografts, xenografts, or mechanical prosthetic devices are frequently implanted during these surgical procedures. These grafts however lack growth potential, are associated with increased risk of thrombosis and infection and have limited durability, thus increasing the morbidity and mortality of their application in pediatric cardiac surgery. These limitations are being addressed through the development of living, biologic tissue-engineered valves, patches, and conduits. Pilot studies and phase 1 clinical trials are currently underway to evaluate their feasibility, safety, and efficacy. The optimal scaffold, cell source, and conditioning parameters, however, still remain to be determined and are areas of active research.

Allergic reaction to a bovine dural substitute following spinal cord untethering. Case report

Bovine tissues are now routinely used for dural closure in cranial and spinal surgery. The authors report the case of an 18-year-old woman with a history of myelomeningocele who had symptoms of tethered cord syndrome and presented to a regional hospital. At that hospital she underwent a cord untethering procedure. The spinal dura was closed with Durepair, a dural substitute derived from fetal bovine skin. Her postoperative course was complicated by a cerebrospinal fluid leak that was surgically repaired. Following this, she developed erythroderma, intermittent fevers, eosinophilia, and marked elevation in serum immunoglobulin E. She was then transferred to the authors' institution. A skin antigen test to beef was administered, which revealed a positive reaction. A radioallergosorbent test to beef also yielded positive results. She was taken to the operating room for removal of the bovine graft due to concern for an allergic reaction to the graft. The graft material showed evidence of eosinophilic infiltration. Her clinical symptoms and laboratory values all improved after surgery. To the authors' knowledge this is the first reported case of an allergic reaction to bovine-based dural substitutes.

Autologous Right Atrial Wall Patch for Closure of Atrial Septal Defects

BACKGROUND

We used the right atrial free wall as a patch to close atrial septal defects (ASD) and report its results.

METHODS

Between July 1998 and April 2006, 87 patients (mean age, 21.9 +/- 13.9 years; range, 7 months to 54 years), underwent closure of ASD with an autologous right atrial free wall patch. The underlying diagnosis were very large secundum ASD in 51 patients, sinus venosus defect in 15, primum ASD in 5, large defect resulting from excision of a left atrial myxoma in 12, complete atrioventricular canal defect in 1, total anomalous pulmonary venous return with ASD in 2, and Ebstein anomaly with a large ASD in 1. Associated surgical procedures were mitral valve repair in 18 patients, repair of total or partial anomalous pulmonary venous drainage in 17, mitral valve replacement in 1, and tricuspid valve repair for Ebstein anomaly in 1.

RESULTS

There were two early deaths. One patient with primum defect and preoperative congestive heart failure died 3 weeks postoperatively from refractory ventricular fibrillation. Another patient died from persistent congestive heart failure after undergoing reoperation for residual mitral regurgitation. The remaining patients were discharged after 4 to 9 days. No flow was detected across the septal patch on predischarge echocardiography. At a mean follow up of 53.4 +/- 26.7 months (range, 1 to 103 months), all patients except 1 are in sinus rhythm. One patient underwent reoperation for failed mitral valve repair after 1 month. At reoperation, the patch was intact with normal texture and without any suture dehiscence. Histopathologic examination of the explanted patch revealed viable endothelium and subendothelial muscle on both the surfaces of the patch. Results of Holter monitoring in 9 patients were normal. Electrophysiologic studies in 2 patients recorded normal atrial potentials from the site of the patch. No patch shrinkage, calcification, or thromboembolic complications were noted.

CONCLUSIONS

The autologous, free, right atrial wall can be safely used as a patch for ASD closure and offers several advantages.

Experience with management of anterior abdominal wall defects using bovine pericard

During 5 years from 1999 until 2003, our experience with 29 (100%) neonates managed for anterior abdominal wall defects is presented. Twenty-one (72%) neonates presented with gastroschisis and 8 (28%) neonates with giant omphaloceles. The male:female ratio was almost equal in gastroschisis (1:1) while a male predominance was observed in omphaloceles (6:1). A primary closure of the defect was possible in 5 (17%) cases and a single patch along with skin closure was achieved in a further 9 (31%) cases. In 15 (52%) neonates the defect was large and two patches were employed to sufficiently cover the defect. All patients (97%), except one (mortality due to extreme prematurity), were managed successfully. Depending upon the size of the defect and the metabolic condition of the neonate, the defect closure was completed after a mean of 85.7 days. Special protocols were created to manage the bovine pericard patches, which behaved differently to lyophilized dura patches previously used at our center. Integration of the patches was successful in 28 (97%) neonates; however, one neonate with gastroschisis presented significant challenges in the management. Bovine pericard patches are optimal biomaterials for the closure of anterior abdominal wall defects in gastroschisis and omphaloceles.

Bovine Pericardial Patch Angioplasty in Carotid Endarterectomy

Patch angioplasty during carotid endarterectomy (CEA) has been shown to reduce the incidence of both early and late complications. Controversy continues, however, over the ideal patch material. Bovine pericardium (Vascu-Guard Biovascular Inc., Saint Paul, MN) offers an attractive alternative to other patch materials because of its handling and suturing characteristics that are similar to that of autogenous material. This study examines the perioperative and midterm results of bovine pericardial patch angioplasty during CEA. We studied 112 patients who underwent 129 CEAs with bovine pericardial patch angioplasty during an 18-month period. Data were collected regarding demographics, operative indications, perioperative complications, and the occurrence of late adverse outcomes based primarily on follow-up arterial duplex studies. Among this group there were 63 male (56%) and 49 female (44%) patients whose mean age was 71.8 ± 9.1 years. In these patients there was the typical distribution of atherosclerotic risk factors. Seventy-four patients (66%) had symptomatic disease preoperatively and the remaining 38 patients (34%) were asymptomatic. Temporary cranial nerve palsy occurred in three patients (2%). There were no perioperative strokes, acute occlusions, bleeding episodes requiring reoperation, or deaths. The patients were followed up to 54 months postoperatively with a mean follow-up time of 41.7 ± 4.4 months. During this period two patients (2%) developed three significant restenoses (70–99%). All required reoperation. There were no asymptomatic occlusions, infections, aneurysms, or rupture. These data demonstrate that bovine pericardial patch angioplasty during CEA is associated with a low incidence of both perioperative and midterm adverse outcomes.

Bovine pericardium as a wrapping for orbital implants

PURPOSE

We report the use of bovine pericardium as an alternative wrapping for porous orbital implants after enucleation.

METHODS

We retrospectively reviewed the records of all patients who received a bovine pericardium-wrapped orbital implant after enucleation by the authors between August 1, 1996, and December 1, 1999.

RESULTS

Eighty patients underwent placement of bovine pericardium-wrapped orbital implants. The average age at the time of implantation was 49.3 years (range, 5 years to 83 years). The mean follow-up interval was 11.8 months (range, 2 to 41 months). There were no intraoperative complications. No patient had secondary systemic infection or showed evidence of rejection. There was no clinical evidence to suggest that vascularization of the porous implant was unusually delayed, and there were no complications after secondary drilling and placement of a coupling post. Four (5%) of 80 patients had complications requiring removal of the spherical implant. All 4 patients had hydroxyapatite implants. Two patients had significant exposure requiring removal of the implant at 2 months after surgery; 1 patient had a chronic fistulous tract with secondary infection 3 years after surgery: and 1 patient had chronic orbital pain requiring removal of the implant at 1 year after surgery.

CONCLUSIONS

The incidence of implant exposure was less than 4%. This compares favorably to the incidence of exposure of 9% to 21% reported in recent literature. Other complications were few and of minimal clinical significance. The authors conclude that bovine pericardium is a viable option to sclera as a wrapping for porous orbital implants.

Crosslinking characteristics and mechanical properties of a bovine pericardium fixed with a naturally occurring crosslinking agent

Currently available crosslinking agents used in fixing bioprostheses are all highly (or relatively highly) cytotoxic, which may induce an adverse inflammatory reaction in vivo. It is therefore desirable to provide a crosslinking agent that is of low cytotoxicty and may form stable and biocompatible crosslinked products. To achieve this goal, a naturally occurring crosslinking agent-genipin-was used by our group to fix biological tissues. Genipin may be obtained from its parent compound, geniposide, which may be isolated from the fruits of Gardenia jasminoides Ellis. In our previous studies, it was found that the cytotoxicity of genipin is significantly lower than both glutaraldehyde and an epoxy compound. Also, it was shown that genipin can form stable and biocompatible crosslinked products. The present study further investigates the crosslinking characteristics and mechanical properties of a genipin-fixed bovine pericardium. Fresh and glutaraldehyde- and epoxy-fixed counterparts were used as controls. It was found that the denaturation temperatures of the glutaraldehyde- and genipin-fixed tissues were significantly greater than the epoxy-fixed tissue, although their fixation indices were comparable. The mechanical properties of fresh bovine pericardium are anisotropic. However, fixation tended to eliminate tissue anisotropy. The tendency in the elimination of tissue anisotropy for the genipin-fixed tissue was more remarkable than for the glutaraldehyde- and epoxy-fixed tissues. In addition, the genipin-fixed tissue had the greatest ultimate tensile strength and toughness among all the fixed tissues. Distinct patterns in rupture were observed in the study: The torn collagen fibers of the genipin- and glutaraldehyde-fixed tissues appeared to be bound together, while those of fresh and the epoxy-fixed tissues stayed loose. The results obtained in the study suggests that tissue fixation in glutaraldehyde, epoxy compound, and genipin may produce distinct crosslinking structures. The differences in crosslinking structure may affect the crosslinking characteristics and mechanical properties of the fixed tissues.

Bovine pericardium for dural grafts: clinical results in 35 patients

OBJECTIVE

The United States Food and Drug Administration has recently approved the marketing of bovine pericardium as a dural graft material, but literature reports of this use are limited. Bovine pericardium has been widely used for grafts in cardiac surgery and seems to have suitable properties for use as a dural graft. We report the use of glutaraldehyde-processed bovine pericardium for dural grafts in 35 patients undergoing cranial and craniospinal operations with the objective of providing a clinical assessment of this material and technique.

METHODS

This report is a retrospective analysis of 35 patients. All available records were reviewed and information regarding the indication for grafting, graft size, complications, and outcome were collected and analyzed for all patients.

RESULTS

Indications for grafting included meningioma resection, posterior fossa craniotomy, Chiari decompression, dural-based metastases, and trauma. Outcomes were good or excellent in 32 patients; the three fair or poor outcomes were not related to surgical closure. In no patient was the dural graft a significant factor in outcome. Bovine pericardium was found to be easily sutured to be watertight using standard suture material. The material is relatively inexpensive and requires no additional incision. It has low antigenicity and toxicity, good strength, and minimal elasticity.

CONCLUSION

In this clinical assessment, bovine pericardium was found to be an excellent dural graft material.

Acute dissection of the right ventricular outflow tract after balloon dilatation in a patient with previously corrected tetralogy of Fallot

Percutaneous balloon dilatation has been used successfully to dilate various stenoses occurring after repair of congenital heart disease. Acute dissection of a stenotic right ventricular outflow tract occurred after attempted balloon dilatation in a patient with previously corrected tetralogy of Fallot.

Mapping of glutaraldehyde-treated bovine pericardium and tissue selection for bioprosthetic heart valves

Glutaraldehyde-crosslinked bovine pericardium is widely used in bioprosthetic heart valve fabrication. In an attempt to set a scientific basis for more reproducible tissue selection, we produced and analyzed topographical maps of glutaraldehyde-treated bovine pericardium. Whole pericardia were divided into specific anatomical areas and their thickness was measured and mapped on templates. In each area, the suture holding power was determined in both parallel and perpendicular (to the base-apex line) directions; analyses of the tearing patterns in each fragment were used to evaluate predominant fiber orientation, and observations were confirmed by polarized light microscopy. Complete maps were superimposed graphically to aid in the selection of certain areas that would have known fiber orientation, high suture holding power, and suitable thickness. Our results describe regional heterogeneity of bovine pericardial structure and mechanical properties, specifically demonstrating variations in thickness, suture holding power, and collagen fiber orientation. Two areas of choice (representing about 35% of the total) were described as suitable for use in bioprosthetic heart valve fabrication.

Lysine-enhanced glutaraldehyde crosslinking of collagenous biomaterials

Crosslinking of collagenous biomaterials currently employs the use of glutaraldehyde. The putative enhancement of glutaraldehyde crosslinking by lysine was investigated in three model systems: bovine pericardium, collagen membranes, and bovine serum albumin. Repetitive sequential treatment of bovine pericardium with glutaraldehyde and lysine and finally with formaldehyde produced a matrix which, by the two criteria used (shrinkage temperature and urea/SDS soluble collagen), was shown to be more highly crosslinked than pericardium fixed in glutaraldehyde alone. Essentially the same results were obtained when membranes prepared from pepsin-soluble pericardial collagen were subjected to sequential glutaraldehyde and lysine treatments, reaching shrinkage temperatures of more than 90 degrees C. Heart valves prepared from lysine-enhanced glutaraldehyde crosslinked bovine pericardium were tested in vitro in an accelerated fatigue tester and have been shown to behave satisfactorily after 300 million cycles. These additional crosslinks proved to be stable in saline at 37 degrees C. Studies on bovine serum albumin attempted to get an insight into the mechanisms of lysine enhancement of glutaraldehyde crosslinking by treating sequentially albumin with glutaraldehyde and lysine and analysis of the products by gel filtration and SDS-PAGE. These studies suggest that free amino groups exposed by proteins are initially reacted with glutaraldehyde and then bridged by the diamino compound (lysine) producing more extensive intermolecular crosslinking than glutaraldehyde alone.

Comparative study of lyophilized human dura mater and lyophilized bovine pericardium as dural substitutes in neurosurgery

In a prospective, controlled randomized study either lyophilized bovine pericardium or lyophilized human dura mater have been used as a patch for the closure of the dura in 102 patients. The aim of this investigation was to compare both materials in terms of immunogenic response of the patients. The rate of post-operative complications was comparably low in both groups (wound infection in 1/51 patients each). In regard of workability, thickness of the material and flexibility the pericardium patches were judged to be by far superior. Neither signs of a cellular nor of an intesified humoral response could be detected in patients who received the pericardium implants. Thus, lyophilized bovine pericardium seems to be a superior alternative for the surgical repair of dural defects.

The bovine pericardial xenograft: I. Effect of fixation in aldehydes without constraint on the tensile viscoelastic properties of bovine pericardium

Tensile testing of tissue strips has been used to examine the effect of simple fixation in glutaraldehyde and formaldehyde on the viscoelastic properties of bovine pericardium. To assess tissue anisotropy, tissue strips were cut at 0 degree, 30 degrees, 60 degrees, and 90 degrees relative to the base-to-apex direction. Fresh anterior pericardium was modestly anisotropic, being least extensible in the base-to-apex direction; however, fixation removed this anisotropy. Fixation also produced a marked change in the response of the material to initial cyclic loading during preconditioning. Overall extensibility of the fixed material was significantly greater than that for the fresh tissue, consistent with a 10.7% shrinkage in aldehydes calculated from strain at fracture data. Reductions in stress relaxation and creep after fixation were noted as well, consistent with intrafibrillar crosslinking. Cyclic hysteresis and ultimate tensile strength were unaffected. Since the observed changes in the stress-strain response were largely attributable to shrinkage, control of shrinkage by physical means would allow for engineering modification of bovine pericardial mechanics for controlled anisotropy.

Partial characterization of a low molecular weight proteoglycan isolated from bovine parietal pericardium

Knowledge of the nature of pericardial connective tissue components is incomplete. To gain a better understanding of the composition of this tissue, bovine parietal pericardium was extracted with 4 M guanidine hydrochloride yielding a proteoglycan-containing protein mixture. This was fractionated by a three-step chromatographic procedure with the resultant purification of a 75-110 Kd proteoglycan. The purified proteoglycan was susceptible to chondroitinase ABC digestion but resistant to chondroitinase AC and nitrous acid degradation suggesting the presence of dermatan sulfate glycosaminoglycan(s). This is the first reported isolation of a proteoglycan from parietal pericardium.

Bovine pericardium: a source of pulmonary venous obstruction in the Mustard procedure

Following Mustard's popularization of the intraatrial baffle procedure for transposition of the great arteries, debate has persisted regarding the ideal materials to use. Reports of xenograft (i.e., bovine pericardium) as a suitable prosthetic material made it an appealing choice. We report our recent experience with 2 patients in whom bovine pericardium was used for atrial augmentation, with subsequent pulmonary venous obstruction. For this reason, we have abandoned this material as an acceptable prosthetic in the Mustard procedure.