Mechanical and structural correlates of canine pericardium.

Abstract

SUMMARY We have assessed viscoelastic properties of pericardium within the physiological range of stresses and related mechanical behavior to fiber direction as defined by scanning electron microscopy. Stiffness, stress relaxation, and creep were measured in samples taken from the anterior surface of 14 canine pericardia. Stress-strain relations generally were not exponential; stiffness at a stress of 1 g/nun* ranged from 12.9 to 239 g/mm l during stretch and varied both from pericardium to pericardium and with the orientation of the strip within the sample (anisotropy). The strips exhibited hyst«retic behavior which was not proportional to rate of strain. Following a rapid increase in stress, creep averaged less than 1% and stress relaxation, 34%, in a 30-minute test period. The orientation of the strip with the greatest stiffness was consistent from pericardium to pericardium, and correlated with a layer of collagen fibers oriented along the major axis of the strip. Circ Res 49: 807-814, 1981 SOME previous studies of the properties of pericardial strips (Rabkin et al., 1974(Rabkin et al., , 1975 have applied large, non-physiological loads to the tissue in order to define such material properties as tensile strength (stress of failure). Others (Vito, 1979) have not taken into account orientation of the strips because of claimed isotropy of the pericardium (Hildebrandt et al., 1969). Finally, no studies have combined detailed analysis of mechanical properties with microscopic examination of the structures responsible for those properties. In the present study, we investigated the elastic and viscoelastic properties of the pericardium, particularly at low stresses, while avoiding high, non-physiological stresses. To relate pericardia! structure to physiology, mechanical properties were related to the orientation of the collagen fibers within the strips, visualized by scanning electron microscopy. Methods A circular sample of parietal pericardium approximately 3 cm in diameter was removed from the Received August 14, 1980; accepted for publication April 7, 1981 anterior surface of the heart of 14 dogs and maintained in oxygenated (95% 0 2 , 5% CO 2 ) Krebs-Henseleit solution at 37°C. Fatty tissue overlying the pericardium was dissected away if necessary. From one to four strips, approximately 2 x 13 mm, were cut from each section, for a total of 42 strips. Adjacent parallel strips were used to test the reproducibility of analysis of mechanical properties, and strips oriented to each other at 45° or 90°C were tested for isotropy of the pericardium. Spring clips were attached to the ends of the pericardial strips which then were studied in an apparatus usually used for isolated papillary muscle studies (Sulman et al., 1974; Wiegner and Bing, 1977) with a force range of 0-10 g. Quantization error was less than 20 mg for force and 5 /xm for length measurements. Length and width of the strips were measured with a Gaertner cathetometer and telescope. Length and force servosystems facilitated computer control of ...

Pericardial Processing: Challenges, Outcomes and Future Prospects

“…Collagen is structured into different levels of organization ranging from fibrils to laminates, fibers and fiber bundles (Allen & Didio, 1984;Lee & Boughner, 1981). This organization determines the mechanical properties of the pericardial tissue (Sacks, 2003;Liao et al, 2005;Wiegner & Bing, 1981;Lee & Boughner, 1985) and provides an anisotropic and non-linear mechanical behaviour (Zioupos & Barbenel, 1994). Interestingly, depending on the location on the pericardium, the thickness and mechanical properties vary (Hiester & Sacks 1998a, 1998b.…”

“…Other pericardial tissues from different species have been assessed or are currently used in clinical practice such as equine (DeCarbo et al, 2010;Yamamoto et al, 2009;Sato et al;, canine Wiegner & Bing, 1981;, or, even more unusually, ostrich (Maestro et al, 2006) or kangaroo pericardium (Neethling et al, 2000;. However, those exogenous grafts raise several issues, and especially the immune response against the bioprosthesis as well as the viral status of the graft.…”

Forced Alignment of Mesenchymal Stem Cells Undergoing Cardiomyogenic Differentiation Affects Functional Integration With Cardiomyocyte Cultures

“…7,8 Any disruption of this architecture, for example, after myocardial infarction, may cause conduction abnormalities associated with diminished pump function and increased risk of arrhythmias. 9 Recently, stem cell therapy has been introduced as a treatment option to improve left ventricular function after myocardial infarction.…”

Thoracic radiographic findings for dogs with cardiac tamponade attributable to pericardial effusion

“…Acute PE is less likely to induce stretching of the pericardium than is chronic PE in humans 4 ; this may also be true for dogs with CT. 5 The capacity of normal pericardial tissue to stretch varies among dogs. 6 Therefore, changes in size of the cardiac silhouette may vary among dogs with equivalent volumes of PE fluid. In addition, pericardial diseases may be associated with a decrease in pericardial compliance for dogs with (effusive-constrictive pericardial disease) or without (constrictive pericarditis) PE.…”

“…4 In the dogs evaluated in this study, PE may not have been present for a sufficiently long period to allow development of pericardial stretching 5 or the pericardium may have been inherently inelastic. 6 The belief that dogs with CT typically have an enlarged, globoid cardiac silhouette in thoracic radiographic images may be attributable to the fact that dogs with CT and those with any type of PE have not been evaluated separately in other studies.…”