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PubMed2000

The influence of chemical treatment and suture on the elastic behavior of calf pericardium utilized in the construction of cardiac bioprostheses.

Poor mechanical properties of biological tissue are known to cause wear, leading to the failure of cardiac bioprostheses made of calf pericardium. Different chemical agents such as sodium dodecyl sulfate (SDS) are presently being tested as possible inhibitors of the calcification process. The objective of this report was to determine the mechanical behavior of calf pericardium treated with SDS for 24 h and the influence of the suture on the mechanical properties of the tissue. Forty-eight samples were tested: 24 subjected to a standard treatment with glutaraldehyde (12 sewn with 4/0 silk suture thread) and 24 incubated with SDS for 24 h (12 sewn with the same suture thread). Each sutured and nonsutured sample was cut into two strips to yield paired samples. All were subjected to tensile stress to breaking point. The mean stress at breaking point in the nonsutured series treated with glutaraldehyde alone was 16.42 and 13.85 MPa, depending on the region of the pericardium, while in the sutured samples subjected to glutaraldehyde the mean stress was 7.50 and 7.63 MPa, respectively, differences which were statistically significant (p=0.03 and p=0.003, respectively) when the means for nonsutured samples from equivalent regions treated with glutaraldehyde were compared. The stress at breaking point was lower in the SDS-treated series, ranging between 2.60 and 3.56 MPa. The mathematical functions that govern the stress/strain or deformation were obtained. In the series of pericardium treated with SDS, deformations of 10% were produced with stresses of under 0.4 MPa, an outcome that is intolerable from the constructive point of view. We established a regression model that enabled us to determine the mechanical behavior of a sutured sample by testing a contiguous piece of tissue, with a high correlation coefficient (r\gt 0.99). We consider this finding to be of interest in the selection of pericardium for use in the construction of leaflets for cardiac bioprostheses.

Journal Article↗
PubMed1999

Polyethylene glycol-grafted bovine pericardium: a novel hybrid tissue resistant to calcification.

Calcification is a frequent cause of the clinical failure of bioprosthetic heart valves fabricated from glutaraldehyde pretreated bovine pericardium (GATBP). An investigation was made of the grafting of different molecular weight polyethylene glycol (PEG 600, 1500, 4000 and 6000) via glutaraldehyde (GA) linkages to bovine pericardium (BP) and of their stability and calcification. The process of the calcification profile was studied by in vitro experiments via incubating pericardial samples in a metastable solution of calcium phosphate. Calcification of bovine pericardium grafted with PEG 6000 was significantly decreased compared to low molecular weight PEG grafts or Sodium dodecyl sulphate- (SDS) and GA-treated tissues. The mechanical properties of these modified tissues after enzyme (Trypsin) digestion and calcification were investigated. The biocompatibility aspects of grafted tissues were also established by monitoring the platelet adhesion, octane contact angle and water of hydration. PEG 6000-grafted tissues retained the maximum strength in trypsin buffer and calcium phosphate solutions. Scanning electron micrographs revealed that the PEG-grafted bovine pericardium had substantially inhibited the platelet-surface attachment and their spreading. It is conceivable that high molecular weight polyethylene glycol-grafted pericardium (a hybrid tissue) may be a suitable calcium-resistant material for developing prosthetic valves due to their stability and biocompatibility.

Journal Article↗
PubMed2000

The influence of chemical treatment and suture on the elastic behavior of calf pericardium utilized in the construction of cardiac bioprostheses.

Poor mechanical properties of biological tissue are known to cause wear, leading to the failure of cardiac bioprostheses made of calf pericardium. Different chemical agents such as sodium dodecyl sulfate (SDS) are presently being tested as possible inhibitors of the calcification process. The objective of this report was to determine the mechanical behavior of calf pericardium treated with SDS for 24 h and the influence of the suture on the mechanical properties of the tissue. Forty-eight samples were tested: 24 subjected to a standard treatment with glutaraldehyde (12 sewn with 4/0 silk suture thread) and 24 incubated with SDS for 24 h (12 sewn with the same suture thread). Each sutured and non-sutured sample was cut into two strips to yield paired samples. All were subjected to tensile stress to breaking point. The mean stress at breaking point in the non-sutured series treated with glutaraldehyde alone was 16.42 and 13.85 MPa depending on the region of the pericardium, while in the sutured samples subjected to glutaraldehyde the mean stress was 7.50 and 7.63 MPa, respectively, differences which were statistically significant (p = 0.03 and p = 0.003, respectively) when the means for non-sutured samples from equivalent regions treated with glutaraldehyde were compared. The stress at breaking point was lower in the SDS-treated series, ranging between 2.60 and 3.56 MPa. The mathematical functions that govern the stress/strain or deformation were obtained. In the series of pericardium treated with SDS, deformations of 10% were produced with stresses of under 0.4 MPa, an outcome that is intolerable from the constructive point of view. We established a regression model that enabled us to determine the mechanical behavior of a sutured sample by testing a contiguous piece of tissue, with a high correlation coefficient (r \gt 0.99). We consider this finding to be of interest in the selection of pericardium for use in the construction of leaflets for cardiac bioprostheses.

Journal Article↗
PubMed1996

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.

Adolescent↗
PubMedDate not supplied

Improved biocompatibility by postfixation treatment of aldehyde fixed bovine pericardium.

Long-standing release of locally cytotoxic aldehyde concentrations is responsible for lack of spontaneous endothelialization and increased calcification of glutaraldehyde fixed bovine pericardium. Postfixation treatment with amino acids made in vitro endothelialization of bioprosthetic heart valves possible. Such treated pericardium calcified significantly less (13 +/- 4 micrograms/mg dry weight) than did conventionally processed pericardium (114 +/- 25 micrograms/mg) after 63 days of subcutaneous implantation in rats. To test the ability for spontaneous in vivo endothelialization, 5 sheep had 6 mm grafts made from postfixation treated pericardium (PTP) implanted into the carotid artery, compared to PTFE grafts on the contralateral side, which spontaneously endothelialize in animal models. In a pregnant animal, both grafts occluded. All remaining pericardial grafts remained patent, but one additional PTFE graft occluded and another one was stenosed. The area covered with red thrombus was significantly smaller in the PTP grafts (3.05 +/- 3.9%) than in the PTFE grafts 42 +/- 14% (p = 0.0036); TEM and SEM showed endothelial cells growing directly on the PTP, but only on myofibroblasts in PTFE grafts. Postfixation treatment of glutaraldehyde fixed pericardium aids spontaneous endothelialization and decreases tissue calcification.

Animals↗
PubMed2004

Hyaluronic acid grafting mitigates calcification of glutaraldehyde-fixed bovine pericardium.

Pathologic calcification is the leading cause of the clinical failure of glutaraldehyde-fixed bovine pericardium used in bioprosthetic valves. A novel surface modification of glutaraldehyde fixed bovine pericardium was carried out with high molecular weight hyaluronic acid (HA). HA was chemically modified with adipic dihydrazide (ADH) to introduce hydrazide functional groups onto the HA backbone. Glutaraldehyde-fixed bovine pericardium (GFBP) was modified by grafting this HA to the free aldehyde groups on the tissue via the hydrazide groups. Following a 2-week subcutaneous implantation in osteopontin (OPN)-null mice, the calcification of HA-modified bovine pericardium was drastically reduced (by 84.5%) compared to positive controls (tissue without HA-modification) (p = 0.005). The calcification-mitigating effect of HA surface modification was also confirmed by microscopic analysis of explanted tissue stained with Alizarin Red S for calcium.

Animals↗
PubMed1990

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.

Animals↗
PubMed1997

Detailed evaluation of 2959 allogeneic and xenogeneic dense connective tissue grafts (fascia lata, pericardium, and dura mater) used in the course of 20 years for duraplasty in neurosurgery.

Surgical experience with 2959 allogeneic and xenogeneic dense connective tissue grafts (1767 of fascia lata, 909 of pericardium, and 283 of dura mater), used in 2665 neurosurgical operations performed in the course of 20 years (1976 to 1995) is reported. Duraplasty using either allogeneic or xenogeneic grafts has had a similar, and favourable clinical outcome. Nevertheless, the pliable deep frozen fascia lata grafts, which could be used in any location, have been reserved for sella turcica plugging, anterior cranial base plasty, aneurysmal wrapping, and surgery of lipomyelomeningocele. Pericardium and dura mater grafts were in the majority of cases used over the brain convexity and posterior cranial fossa. Ovine pericardium proved to be superior to bovine and allogeneic pericardia because of its workability, flexibility, reduced thickness, and better transparency. Postsurgical complications occurred in 7.3%, and they were: 1) cerebrospinal fluid fistulas in 2.8%; 2) meningites in 2.3% (aseptic 1.4%, bacterial 0.8%, and tumoural 0.1% meningites); 3) pseudomeningoceles in 2.2%; 4) wound infections in 0.6%; 5) malresorptive hydrocephalus in 0.5%; and 6) adhesions to nerve tissue in 0.5%. The majority of complications healed without surgery. Forty-eight grafts (1.6%) failed to fulfil the requirements of the surgeon, and 46 of them were re-operated upon. Though another thirty-nine grafts healed successfully, 39 shunts (1.5%) had to be performed for malresorptive hydrocephalus (0.9%), and/or for a big pseudomeningocele (0.6%). So, the pure complication rate in 2665 duraplasties was 3.1%. The complex evaluation of the allogeneic and xenogeneic grafts (fascia, pericardium, and dura mater), used for duraplasty in neurosurgery during the last 20 years proved them, as remarkably good, with a success rates of 96.9%.

Adult↗
PubMed2001

Bovine pericardium for duraplasty: clinical results in 32 patients.

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 on the use of solvent-preserved, gamma-sterilized Tutoplast bovine pericardium for dural grafts in 32 patients undergoing cranial and spinal operations with the objective of clinically assessing this material and technique by a retrospective analysis. All available records were reviewed and information regarding the indication for grafting, complications, and outcome were collected and analyzed for all patients. Indications for grafting included tethered cord myelolysis, closure of lumbosacral myeloceles, Chiari decompression, posterior fossa craniotomy, supratentorial craniotomy, and trauma. Outcomes were excellent in 31 patients; the one poor outcome was unrelated to surgical closure. The dural graft was not intended for outcome in any patient. Bovine pericardium was found to be a flexible and easily suturable, safe and cost-effective material for duraplasty. These results confirm the excellent suitability of Tutoplast bovine pericardium for dural substitution.

Adolescent↗
PubMed1999

Maximal thickness of the normal human pericardium assessed by electron-beam computed tomography.

The purpose of this study was to determine the maximal value of normal pericardial thickness with an electron-beam computed tomography unit allowing fast scan times of 100 ms to reduce cardiac motion artifacts. Electron-beam computed tomography was performed in 260 patients with hypercholesterolemia and/or hypertension, as these pathologies have no effect on pericardial thickness. The pixel size was 0.5 mm. Measurements could be performed in front of the right ventricle, the right atrioventricular groove, the right atrium, the left ventricle, and the interventricular groove. Maximal thickness of normal pericardium was defined at the 95th percentile. Inter-observer and intra-observer reproducibility studies were assessed from additional CT scans by the Bland and Altman method [24]. The maximal thickness of the normal pericardium was 2 mm for 95 % of cases. For the reproducibility studies, there was no significant relationship between the inter-observer and intra-observer measurements, but all pericardial thickness measurements were </= 1.6 mm. Using electron-beam computed tomography, which assists in decreasing substantially cardiac motion artifacts, the threshold of detection of thickened pericardium is statistically established as being 2 mm for 95 % of the patients with hypercholesterolemia and/or hypertension. However, the spatial resolution available prevents a reproducible measure of the real thickness of thin pericardium.

Female↗
PubMed2002

Comparison of PTFE, pericardium bovine and fascia lata for repair of incisional hernia in rat model, experimental study.

Incisional hernia is a frequent complication of abdominal surgery developing in 11-20 % of patients undergoing an abdominal operation. Regarding morbidity and loss of manpower, incisional hernias continue to be a fundamental problem for surgeons. In this experimental study, three commonly used mesh materials (Goretex PTFE; Tutoplast Fascia lata; Tutopatch Pericardium bovine) were compared according to effectiveness, strength, adhesion formation, histological changes, and early complications. Three groups, each consisting of 14 rats, have been formed as group A: polytetrafluoroethylene (PTFE), group B: pericardium bovine and group C: fascia lata. Evaluations were achieved at the end of the first and second postoperative week, respectively. Adhesion formation, wound maturation, bursting pressure, and tensile strength were evaluated. No statistically significant difference regarding adhesion formation was observed between groups although adhesion formation was less significant in PTFE and pericardium bovine groups than in the fascia lata group. Bursting pressure and tensile strength values were significantly higher in PTFE group than in the fascia lata group ( P<0.05). No statistically significant difference was observed between groups regarding wound maturation. In this experimental model, PTFE and pericardium bovine were found to be superior to fascia lata in abdominal wall repair.

Animals↗
PubMed1990

The effects of lying position on ventricular volume in congenital absence of the pericardium.

In patients with congenital absence of the left pericardium, the heart is supported by the existing right pericardium in the right lateral position, while it is not in the left lateral position. To investigate the change in ventricular size resulting from postural change, seven patients with this malformation were examined. Ventricular volumes were calculated by computed tomography, integrating areas of computed tomographic cross sections measured at 1 cm intervals from the cardiac apex to the aortic arch. In the right lateral position, right ventricular (RV) and left ventricular (LV) volumes were no different from those of five control subjects. With a change in the lying position to the left, the increase in the ventricular volume was significantly greater than that in the control subjects (35 +/- 11 versus 3 +/- 3 ml in the right ventricle and 15 +/- 13 versus 3 +/- 8 ml in the left ventricle). The increases in RV and LV end-diastolic pressure, however, were almost the same as those in the 11 control subjects. It is concluded that the cardiac ventricle, especially the right ventricle, dilates significantly with a small increase in preload in patients with congenital absence of the pericardium. It may be a clue for clarifying the ventricular distensibility being freed from physiologic restraint of the pericardium for a long period.

Adult↗
PubMed1996

Calcification of bovine pericardium: glutaraldehyde versus No-React biomodification.

BACKGROUND: Calcific degeneration is the most frequent cause of clinical dysfunction of glutaraldehyde (GA)-pretreated bioprosthetic heart valves. The No-React (NR) process has been shown to be a promising anticalcification treatment. In this comparative study, our objective was to delineate the advantages of the NR treatment over GA. METHODS: Bovine pericardial strips pretreated with GA and NR were individually incubated in calcium phosphate solution for 21 days at 37 degrees C. The pretreated bovine pericardium then was implanted subcutaneously in rats and retrieved at 14, 21, and 35 days after-implantation. Mineral and morphologic analyses were performed on each specimen. RESULTS: The NR-treated pericardium revealed significantly reduced in vitro calcification compared with the GA-treated tissue (mean tissue calcium content 1.3 +/- 0.2 versus 5.9 +/- 0.7 micrograms/mg; p < 0.001). Mineral analysis showed progressive calcification of the GA-pretreated pericardium over the period of implantation (calcium content increasing from 49.6 +/- 9.6 micrograms/mg after 2 weeks to 134.3 +/- 9.1 micrograms/mg at 5 weeks after-implantation). The NR-treated implants had calcified significantly less (p < 0.05) at each corresponding interval. Moreover, morphologic examinations demonstrated a protracted inflammatory response in the form of giant cell and mononuclear cell infiltration associated with intrinsic collagen disruption in the GA-treated tissue; the NR-treated pericardium maintained morphologic integrity with a mild inflammatory response. CONCLUSIONS: The NR biochemical process appears not only to attenuate pericardial calcification, but also to abort the host's destructive inflammatory response to the xenograft.

Animals↗
PubMed1995

Cytocompatibility of calf pericardium treated by glutaraldehyde and by the acyl azide methods in an organotypic culture model.

Glutaraldehyde (GTA) is used to cross-link collagen-based biomaterials, but these materials are often cytotoxic. In order to overcome this problem, we have proposed the use of the acyl azide methods with either hydrazine or diphenylphosphoryl azide (DPPA) as reagents. In this paper we determine the cytocompatibility of acyl azide- and GTA-treated pericardium in vitro, by an organotypic chick aorta culture technique developed for the evaluation of the propensity of vascular cells (both endothelial and smooth muscle cells) to migrate and grow on the surface of biomaterials. We first examined pericardium stabilization as a function of GTA concentration and time, so that we could minimize residual GTA molecules in the material. Treatment for 72 h with 0.05% GTA was optimal for thermal stabilization of the pericardium with a denaturation temperature (Td) of 86.8 degrees C, providing similar results to treatment with 0.6% GTA for 4 h (Td = 85.1 degrees C). Pericardium treated in this way was, however, poorly cytocompatible with little vascular cell migration and growth when compared with tissues treated by the acyl azide methods. The best results were obtained with 0.5% DPPA; treated tissues showed a high level of cross-linking (Td = 82.4 degrees C) and three-fold increases in cell growth and migration over those in a non-toxic control.

Animals↗
PubMed1991

Studies of reflexogenic effects of capsaicin and neuropeptides on neural afferents in the dog parietal pericardium.

Stimulation of neural afferents in the parietal pericardium of anaesthetized, open-chest dogs by local application of capsaicin (0.1-100 micrograms) consistently induced dose-related pressor effects and tachycardia, whereas the application (0.1-1 microgram) of neuropeptides substance P (SP), neurokinin A (NKA), neurokinin B (NKB) or calcitonin gene-related peptide (CGRP) had no cardiovascular effect. Capsaicin-induced reflex responses were not affected by vagotomy, but were abolished by bilateral sectioning of the upper thoracic (T1-T4) white rami communicantes and stellectomy. Capsaicin-induced reflex tachycardia could also be abolished by a beta-adrenoceptor blockade with propranolol (0.5 mg/kg, IV), while ganglionic blockade with pentolinium (0.5 mg/kg, IV) eliminated both the tachycardia and pressor effects. Intravenous treatment with the cyclo-oxygenase inhibitors, indomethacin (5 mg/kg) or aspirin (100 mg/kg) had no effect on reflex pressor and heart rate responses to pericardial capsaicin. Also local treatment of the pericardium with either indomethacin (1 microgram/ml) or dual cyclooxygenase/lipoxygenase inhibitor, BW755C (10 micrograms/ml) failed to affect the responses to capsaicin. We conclude that (i) capsaicin-sensitive afferents which are present in the dog pericardium have a spinal origin and can initiate sympathetically-mediated reflex cardiovascular changes; (ii) the reflexogenic action of capsaicin on pericardial afferents does not depend on local production of eicosanoids; (iii) neuropeptides appear to be without reflexogenic effects on neural afferents in the dog parietal pericardium.

Afferent Pathways↗
PubMed1989

Insulin-like growth factor I (IGF-I) enhances hyaluronic acid synthesis in rabbit pericardium.

We examined which substances stimulate hyaluronic acid synthesis in rabbit pericardium and pericardial cells. (1) The addition of 10% (v/v) pericardial fluid to the incubation medium of the pericardium enhanced hyaluronic acid synthesis to about 2.5-times over the control, suggesting that there were some stimulating factors of the hyaluronic acid synthesis in the pericardial fluid. (2) The addition of 100 ng/ml insulin-like growth factor-I (IGF-I) to the incubation medium caused an approx. 2-fold increase of hyaluronic acid synthesis over the control in the pericardium. (3) IGF-I stimulated the hyaluronic acid synthesis in pericardial cells in a dose-dependent manner, but did not significantly stimulate the sulfated glycosaminoglycan synthesis. (4) The increase in the hyaluronic acid synthesis induced by IGF-I (100 ng/ml) or pericardial fluid was blocked by the copresence of monoclonal anti-IGF-I antibody. (5) IGF-I caused possible induction of the hyaluronic acid synthase activity and general protein and RNA synthesis before the initiation of DNA synthesis in pericardial cells. These results suggest a new biological action of IGF-I that stimulates hyaluronic acid synthesis in pericardium or the pericardial cavity of heart.

Animals↗
PubMed1993

Effect of the pericardium on systolic ventricular interdependence in the dog.

Systolic ventricular interdependence, whereby changes in left ventricular (LV) ejection alter right ventricular (RV) ejection, has been described. It is unclear, however, whether this interaction is influenced by pericardial volume constraint or by myocardial mechanical coupling. We hypothesized that if mechanical coupling were the primary factor determining systolic ventricular interdependence then it should be unaltered by the presence or absence of an intact pericardium, but affected by changes in LV end-systolic volume. We tested this hypothesis by observing the changes in RV stroke volume (SVrv) and peak systolic pressure (PSPrv) during a single LV isovolumic contraction under conditions of normal or increased (1.3 x normal) RV end-diastolic volume with and without an intact pericardium. In 10 anesthetized, open-chested dogs SVrv was derived from the integrated pulmonary arterial flow probe signal and RV ejection fraction (EFrv) was derived from the thermodilution plateau method and a rapidly responsive thermistor in the pulmonary artery. Right ventricular end-diastolic volume was considered to be the ratio of SVrv to EFrv. Left ventricular isovolumic contraction increased SVrv and PSPrv during all conditions (P < .01). However, PSPrv increased more when the pericardium was intact (P < .05). These data suggest that LV ejection can enhance SVrv and that this interaction is not appreciably altered by volume loading or the presence of an intact pericardium. Pericardial interactions may alter PSPrv but do not affect SVrv.

Animals↗
PubMed2006

mu-Opioid influence on transmesothelial resistance of isolated sheep pleura and parietal pericardium.

The effect of morphine (mu-opioid receptor agonist) on the transmesothelial resistance (R(TM)) of sheep's pleura and parietal pericardium was studied using the Ussing chamber technique. Basal transmesothelial resistance of parietal pleura was found to be 19.57+/-0.32 Omega cm2 and of visceral pleura was found to be 19.41+/-0.31 Omega cm2, whereas that of parietal pericardium was found to be 22.83+/-0.4 Omega cm2. Immediately after the addition of morphine (10(-9) M) both apically and basolaterally on the parietal pleura and parietal pericardium, these values were significantly increased (P<0.05). On the contrary, addition of morphine (10(-9) M) resulted in a rapid increase, only when placed basolaterally on the visceral pleura (P<0.05). In conclusion, our findings suggest that morphine, probably through mu-opioid stimulation, increases in vitro the transmesothelial resistance of the parietal pleura, of the visceral pleura when added basolaterally and of the parietal pericardium.

Analgesics, Opioid↗