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Results for “PERICARDIUM”

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At least 19 recordsLinked to original sources
PubMed1985

Mechanical properties of human pericardium. Differences in viscoelastic response when compared with canine pericardium.

Whereas most experiments on the mechanical function of the pericardium have been performed on dogs, very little is known about the applicability of those data to humans. To examine the tensile viscoelastic properties of fresh human pericardium, we have used the methods from our previous study of canine pericardium. Although the mechanical responses of canine and human pericardium were qualitatively similar, human pericardium displayed a significantly greater viscous character. Human pericardium was 7.3 times thicker than canine pericardium, but was more extensible in stress-strain tests, with lower stiffness at a given strain. The static (elastic) stiffness of human pericardium seems identical to that of canine pericardium; lower stiffness per unit thickness of the human tissue at predicted physiological stresses was almost exactly compensated by the greater wall thickness. This effect was also seen in data on fracture strength and stiffness. However, human pericardium displayed greater viscous responses than the canine tissue. This was seen in doubled cyclic hysteresis losses, and greater stress relaxation and creep. Our results suggest that experiments on the viscoelastic properties of canine pericardium may not be directly applicable to humans, especially where dynamic mechanical properties are most important: i.e., in studies of ventricular function and the time-course of pericardial effusions.

Adult↗
PubMed2003

In vitro study of bacterial adherence to processed dura mater, processed pericardium, pericardium in saline, and human sclera.

PURPOSE: To study bacterial adherence to processed dura mater, processed pericardium, pericardium in saline, and human sclera and the difference in bacterial adherence to these tissues. SETTING: Research Laboratory, Loyola University Medical Center, Maywood, Illinois, USA. METHODS: Specimens of processed dura mater, processed human pericardium, pericardium in saline, and human sclera (N = 32) were exposed to Staphylococcus epidermidis (concentration 3 x 10(8)) for 10, 20, 40, and 60 minutes, washed for 5 seconds, fixed, and processed for scanning electron microscopy (SEM). Each bacterial count represents an average of 50 random SEM fields at x5,000 magnification. After SEM, selected specimens were processed for transmission electron microscopy. RESULTS: The mean number of bacteria/mm(2) +/- SD adhering to the tissues at 10, 20, 40, and 60 minutes, respectively, were dura mater, 107,833 +/- 65,410, 104,500 +/- 13,471, 96,067 +/- 113,884, and 204,267 +/- 153,697; processed pericardium, 131,550 +/- 86,194, 100,900 +/- 20,031, 144,683 +/- 51,730, and 176,933 +/- 111,818; pericardium in saline, 7,925 +/- 1,520, 33,933 +/- 32,085, 1,217 +/- 1,287, and 21,550 +/- 16,436; and human sclera, 4,850 +/- 2,121, 23,700 +/- 17,961, 5,150 +/- 1,273, and 8,175 +/- 8,450. A 2-way analysis of variance showed significant differences among groups (P =.001) and no significant difference in sample time (P =.929). CONCLUSIONS: Bacterial adherence to processed dura mater, processed pericardium, pericardium in saline, and human sclera should be considered when these materials are used clinically during ophthalmic surgery and other surgical specialties. Adequate broad-spectrum antibiotic coverage is needed to prevent infection and subsequent complications in patients.

Bacterial Adhesion↗
PubMedDate not supplied

Reflex effects evoked from the parietal pericardium in the dog: comparison with responses from the visceral pericardium.

Experiments were performed on anaesthetized, open-chest dogs to determine the reflex effects on systemic blood pressure and heart rate produced by stimulation of the parietal pericardium with bradykinin and nicotine, and to compare these effects with those evoked by application of these substances to the visceral pericardium (epicardium) of the left ventricle. Bradykinin (0.01-6.0 micrograms) elicited reflex increases in blood pressure and heart rate when applied either to the parietal pericardium or to the ventricular epicardium; the responses evoked from both sites were dose-dependent from the threshold of 0.01 micrograms to a maximum at 1.0 micrograms of bradykinin. The reflex effects of bradykinin were not affected by either vagotomy or phrenic nerve section, but were suppressed by bilateral sectioning of the upper thoracic (T1-T4) white rami communicantes and stellectomy. In contrast to bradykinin, nicotine (20-100 micrograms) failed to produce any change in blood pressure and heart rate when applied to the parietal pericardium and evoked depressor responses when applied to the epicardium of the left ventricle; these depressor effects of nicotine were abolished by vagotomy. The results indicate that sympathetic, but not vagal, afferent endings innervating the parietal pericardium are susceptible to chemical stimulation. Bradykinin is a powerful algesic agent and is formed and released locally during inflammation. We suggest, therefore, that the pericardial sympathetic pressor reflex is nociceptive in nature and can be activated when kinin formation occurs during pericardial inflammation.

Animals↗
PubMed1990

Pericardium as a thoracic aortic patch: glutaraldehyde-fixed and fresh autologous pericardium.

The repair of complex coarctation of the aorta often requires an aortic patch. Prosthetic patches lack growth potential and are associated with an increased incidence of aneurysm formation opposite the patch. We compared buffered glutaraldehyde-fixed patches, used in six animals (group 1), and untreated autologous pericardial aortic patches, used in five animals (group 2). Weanling pigs underwent pericardial patch replacement of a 1 X 2-cm diamond-shaped segment of the lateral wall of the descending thoracic aorta at the level of the aortic isthmus. Six months following patch aortoplasty, the animals were killed and the in situ patch dimensions were measured and compared to the measurements obtained at implantation. The increases in length, recorded as mean percentage change +/- SEM, were 34.7 +/- 3.7% for group 1 and 102.8 +/- 20.3% for group 2 animals; the increases in width were 91.4 +/- 31.7% for group 1 and 192.4 +/- 31.4% for group 2. The percentage changes for both length and width were significantly different between groups (P less than 0.05). Pull strength testing of standard-size patch samples demonstrated no significant difference in tensile breaking load between groups: group 1 = 959 +/- 277 g, group 2 = 795 +/- 86 g. Thoracic aortography revealed no evidence of stenosis or aneurysmal dilation in either group. Autologous pericardium is resilient, strong, and readily available and has expansile potential that makes it an ideal aortic patch material. We conclude that glutaraldehyde fixation does not provide additional strength and limits graft expansile potential when compared to untreated pericardium.

Animals↗
PubMed1982

Clinical experience with glutaraldehyde-preserved heterologous pericardium for the closure of the pericardium after open heart surgery.

A limited series of 58 patients had their pericardial cavity closed with a patch of heterologous glutaraldehyde-preserved pericardium. No patients have been lost to follow-up, which extends between 3 hours and 50 months with a mean of 21 months. No problems related to the patch have been detected. Nine specimens have been available for macroscopic examination and 5 for microscopic study with a maximum postimplant time of 6 months. The patch maintained its initial structure, remained acellular and offered a retrosternal and intrapericardial plane of cleavage.

Animals↗
PubMed2005

Effect of freeze-drying and gamma irradiation on biomechanical properties of bovine pericardium.

Freeze-drying and gamma irradiation are the techniques widely use in tissue banking for preservation and sterilization of tissue grafts respectively. However, the effect of these techniques on biomechanical properties of bovine pericardium is poorly known. A total of 300 strips of bovine pericardium each measured 4 cm x 1 cm were used in this study to evaluate the effect of freeze-drying on biomechanical properties of fresh bovine pericardium and the effect of gamma irradiation on biomechanical properties of freeze-dried bovine pericardium. The strips were divided into three equal groups, which consist of 100 strips each group. The three groups were fresh bovine pericardium, freeze-dried bovine pericardium and irradiated freeze-dried bovine pericardium. The biomechanical properties of the pericardial strips were measured by a computer controlled instron tensiometer while the strips thickness was measured by Mitutoyo thickness gauge. The results of the study revealed that freeze-drying has no significant (p > 0.05) effect on the tensile strength, Young's modulus (stiffness) and elongation rate of fresh bovine pericardium. Irradiation with 25 kGy gamma rays caused significant decreased in the tensile strength, Young's modulus and elongation rate of the freeze-dried pericardium. However, gamma irradiation has no significant effect on the thickness of freeze-dried bovine pericardium, while freeze-drying caused significant decreased in the thickness of the fresh bovine pericardium. The outcome of this study demonstrated that freeze-drying has no significant effect on the biomechanical properties of fresh bovine pericardium, and gamma irradiation caused significant effect on the biomechanical properties of freeze-dried bovine pericardium.

Animals↗
PubMed2006

Biochemical and mechanical behavior of ostrich pericardium as a new biomaterial.

We have performed a comparative analysis of glutaraldehyde-preserved ostrich pericardium, as a novel biomaterial, with bovine pericardium. The biochemical characteristics (histology, water content, amino acid composition, and collagen and elastin contents), mechanical properties, and in vivo calcification in a subcutaneous rat model were examined. Ostrich pericardium is slightly thinner and shows a higher water content (70+/-2% vs. 62+/-2%) than bovine pericardium. Additionally, ostrich pericardium presents 1.6-fold lower elastin content and a lower percentage of collagen in reference to the total protein content (68+/-2% vs. 76+/-2%). However, ostrich pericardium shows better mechanical properties, with higher tensile stress at rupture (32.4+/-7.5 vs. 11.5+/-4.6) than calf pericardium. In vivo calcification studies in a rat subcutaneous model show that ostrich pericardium is significantly less calcified than bovine pericardium (23.95+/-13.30 vs. 100.10+/-37.36 mg/g tissue) after 60 days of implantation. In conclusion, glutaraldehyde-stabilized ostrich pericardium tissue shows better mechanical properties than calf tissue. However, calcium accumulation in implanted ostrich tissue is still too high to consider it a much better alternative to bovine pericardium, and anticalcification treatments should be considered.

Animals↗
PubMed1992

Effects of the pericardium on left ventricular diastolic filling and systolic performance early after cardiac operations.

To determine whether closure of the pericardium after cardiac operations affects the filling characteristics and systolic performance of the left ventricle, we measured left ventricular volume, pressure, cardiac index, and stroke work index in 10 patients between 11 and 15 hours after cardiac operations, with the pericardium first closed and then open. At the time of operation, radiopaque tantalum markers were inserted in the left ventricular myocardium to outline the chamber in the 30-degree right anterior oblique projection, and the pericardium was closed by a continuous polypropylene suture exteriorized at both ends of the sternotomy. The patient was then transferred to the surgical intensive care unit, where left atrial pressure was measured via a fluid-filled catheter, left ventricular pressure with a micromanometer-tipped catheter, and myocardial oxygen consumption via a coronary sinus catheter. Left ventricular volume was measured by computer-aided analysis of fluoroscopic images (recorded at 30 frames per second) of the implanted myocardial markers. Left atrial pressure was maintained at target values of 10, 15, and 20 mm Hg by intravenous augmentation of blood volume. Left ventricular and left atrial pressures and volumes were measured with the pericardium closed; the pericardium was then opened by withdrawal of the pericardial suture. Radiopaque clips on the pericardial edges confirmed opening of the pericardium seconds after withdrawal of the suture. Repeated measurements of left ventricular pressures and volumes were then made at the target left atrial pressures with the pericardium open. End-diastolic volume index, peak positive time derivative of pressure, stroke work index, and cardiac index all increased significantly when the pericardium was opened (p < 0.001). Thus we found the following: (1) At physiologic pressures, the pericardium had a significant constraining effect on diastolic filling of the left ventricle, and (2) opening of the pericardium resulted in increased cardiac index and stroke work index. These increases may be attributed to the Frank-Starling response to increased left ventricular preload. The demonstrated improvement in left ventricular systolic performance should be considered when contemplating closure of the pericardium after cardiac operations, especially in patients with preoperative left ventricular dysfunction.

Adult↗
PubMed1986

Autologous pericardium versus a xenograft substitute in myocardial wound healing.

This study compared repair of myocardial wounds covered with autologous pericardium to healing of wounds covered with glutaraldehyde-preserved bovine pericardium in an experimental canine model. Right (RV) and left (LV) full thickness ventriculotomies were made and closed. In the control group (n = 12), the pericardium was closed over the wound; in the experimental group (n = 12), wounds were covered with bovine pericardium. Animals were sacrificed at 14, 21, 28, and 42 days. After excising the pericardium, 6 mm punch biopsies of normal RV, RV wound, normal LV, and LV wound were assayed for hydroxyproline (HPro). Both autologous and bovine pericardium became densely adherent to the wounds. Bovine pericardium was mildly adherent over unwounded areas, while autologous pericardium was usually free. Normal RV contained more than twice as much HPro as normal LV (5.4 +/- 0.57 micrograms/mg vs 1.7 +/- 0.35 micrograms/mg, P less than 0.0002). A gradual rise in HPro over time was seen in both groups, but this increase was statistically significant only at 42 days (P less than 0.05). There was no significant difference in HPro between wounds covered with autologous pericardium and those covered with bovine grafts (P = 0.13) at any of the sample times in this study. In this experimental canine model, the pericardium does not appear to play a prominent role in myocardial wound healing by contributing collagen-producing fibroblasts. Furthermore, the bovine pericardial xenograft becomes densely adherent to LV and RV incisions. In the clinical setting, such may make reoperation more hazardous when the heart has been previously incised or coronary bypass grafts have been constructed.

Animals↗
PubMed2001

Synthetic membrane neo-pericardium facilitates total artificial heart explantation.

BACKGROUND: In the past, explantation of the Cardio West total artificial heart (TAH) has been technically challenging because of the presence of dense adhesions and extremely thickened pericardium. To prevent this, we constructed a synthetic neo-pericardium in 14 patients. METHODS: Using expanded polytetrafluoroethylene (e-PTFE) membrane, we constructed a pericardium within the pericardium, or "neo-pericardium," completely covering the Cardio West TAH separating the native atria from the native pericardium, and wrapping the ascending aorta from the outflow conduit distally for about 5 to 7 cm. RESULTS: Of the 14 patients, 9 were transplanted and could be evaluated, 3 died on device support, and 2 are currently on device support. In each case, we attained faster (by 25 minutes) and easier reentry through the sternum. Surgical planes around the aorta, over the right and left atria, and throughout the pericardial space became apparent immediately after e-PTFE membrane removal. The pericardium and related tissues although slightly thickened (<2 mm) were pliable compared with our previous 36 patients, with very thick adherent pericardium over the device and native atria. CONCLUSIONS: The plastic materials forming the ventricular housing and drivelines of the Cardio West TAH and the Dacron outflow conduits have in the past caused profound local inflammatory reactions, resulting in extremely dense adhesions and thickened adherent pericardium. Using e-PTFE membrane to fashion a complete neo-pericardium and to wrap the ascending aorta at the time of Cardio West implantation dramatically reduces adhesions and pericardial thickening and facilitates explantation.

Adult↗
PubMed2003

Bovine pericardium versus homologous sclera as a wrapping for hydroxyapatite orbital implants.

PURPOSE: To report our experience with bovine pericardium as a wrapping material for hydroxyapatite orbital implants after enucleation and to compare the exposure rates of the implants wrapped with bovine pericardium versus donor sclera. METHODS: We retrospectively reviewed the records of all patients who received bovine pericardium-wrapped or donor sclera-wrapped hydroxyapatite implant after primary enucleation between March 1995 and December 2001. RESULTS: Of the 26 patients who received donor sclera-wrapped implants after enucleation, 1 (3.8%) had implant exposure. Of the 26 patients who received bovine pericardium-wrapped implants after enucleation, 6 (23%) had implant exposure. The incidence of implant exposure with the use bovine pericardium wrapping material was found to be significantly higher than with sclera (P = 0.05). Six of the 7 implant exposures were noted in the first 6 months after placement of the orbital implant. Five of the 6 exposed bovine pericardium-wrapped hydroxyapatite implants were associated with socket infection. The case of exposure of the sclera-wrapped implant was treated conservatively by observation. Six patients who had exposure of bovine pericardium-wrapped implants required multiple repairs because of recurrent exposures. Four of these patients eventually required removal of the implant. CONCLUSIONS: Despite the advantages of using bovine pericardium as a wrapping material for hydroxyapatite orbital implants, we observed a significantly higher incidence of exposure with bovine pericardium compared with donor sclera in the early postoperative period. Use of bovine pericardium as a wrapping material for orbital implants should be avoided unless some future modifications of the technique can be developed to prevent such complications.

Adolescent↗