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Mechanical properties of the toad aorta in vivo and in vitro
8Y
Abstracts
Department
BIOMECHANCISOF THE ANASTOMOTICJUNCTION Harvey S. Borovetz and Victor G.J. Rodgers of Surgery, University of Pittsburgh School of Medicine Pittsburgh, PA 15261, U.S.A.
The present study is undertaken to determine, from experimental data, the shearing stress acting at the anastomotic interface between native vessel and various vascular substitutes. The experimental protocol involves the use of canine carotid arteries as the host vessel and several graft materials, including autogenous and prosthetic substitutes. The host artery-graft combinations are perfused in vitro in a pulsatile perfusion This apparatus provides apparatus which aimulates the natural hemodynamicenvironment. accurate dynamic measurements of the radial motion of the anastomotic junction along with associated pressures and rates of flow. From these data calculations are made of anastomotic induced shearing stress. The results suggest that the magnitude of shearing me stress is dependent on which vascular substitute is anastomosed to the host vessel. region of maximum shear stress lies within 2 mm of the suture line.
THE MORPHOLOGICALAND BIOMECHANICALPROPERTIES OF THE FIN WHALEAORTA Robert E. Shadwick and John M. Gosline, Department of Biology, University of Calgary, Calgary, Alberta, and Department of Zoology, University of British Columbia, Vancouver, B.C. Canada. We investigated the morphological and biomechanical properties of the aorta of the Fin whale Balaenoptera physalus to determine if any mechanical adaptations were present which might be important in hemodynamics, particularly with respect to long periods of diastole during diving. The most striking feature was the very large and bulbous aortic arch, which had far greater distensibility than the smaller diameter thoracic and abdominal aortae. In vitro inflation tests showed that over the expected physiological pressure range of 10 to 18 kPa the aorta would transiently store 60L of blood, while Measurements of stress-strain the thoracfc aorta would take only 1.6L. relationships and incremental elastic modulus indicated that the arch was more extensible, less non-linear and less stiff than the rest of the aorta. Pressure wave velocity was calculated as 6.4 m/s in the arch and 17 m/s in the thoracic and abdominal aortae. The elastin content was 39% in the arch and 25 x in the thoracic aorta. The aortic arch in the whale appears to be adapted to provide a substantial ‘Windkessel’ effect in the arterial circulation.
MECHANICAL PROPERTIES OF THE TOAD AORTA -IN VIVO AND -IN Carol A. Gibbons and Robert E. Shadwick Department of Biology, University of Calgary, Calgary,
VITRO Alberta,
Canada
The Arterial mechanical properties are important determinants of hemodynamics. mechanical properties of the toad aorta were studied by inflation tests of vessel The stress-strain curves had a non-linear “J” shape, similar to segments -in vitro. Stiffness increased with the degree of distention, and those described for mammals. the incremental modulus increased dramatically with pressure, having values comparable and aortic diameter pulses were also to those for mammals. In vivo pressure, flow, measured. Pressure-flowrelationships in transmission line systems are characterized The toad was found by wave propagation effects such as reflection and attenuation. Because of its short arterial tree, it is to have a low resting heart rate of 0.6 Hz. possible to represent it by a simpler Windkessel model, where the aorta acts as an The impedence spectrum had a elastic resevoir to the stiffer vascular resistance. sharp initial decrease and showed no detectable oscillations, and the pressure pulse showed no change in shape and little attenuation when propagated through the aorta. The pressure pulse was transmitted from the heart to the iliac bifurcation in 0.08 set or 52 of the cardiac These results support the idea that the toad aorta has cycle. suitable mechanical properties to function as a Windkessel in the circulatory system-
Abstracts
Department
BIOMECHANCISOF THE ANASTOMOTICJUNCTION Harvey S. Borovetz and Victor G.J. Rodgers of Surgery, University of Pittsburgh School of Medicine Pittsburgh, PA 15261, U.S.A.
The present study is undertaken to determine, from experimental data, the shearing stress acting at the anastomotic interface between native vessel and various vascular substitutes. The experimental protocol involves the use of canine carotid arteries as the host vessel and several graft materials, including autogenous and prosthetic substitutes. The host artery-graft combinations are perfused in vitro in a pulsatile perfusion This apparatus provides apparatus which aimulates the natural hemodynamicenvironment. accurate dynamic measurements of the radial motion of the anastomotic junction along with associated pressures and rates of flow. From these data calculations are made of anastomotic induced shearing stress. The results suggest that the magnitude of shearing me stress is dependent on which vascular substitute is anastomosed to the host vessel. region of maximum shear stress lies within 2 mm of the suture line.
THE MORPHOLOGICALAND BIOMECHANICALPROPERTIES OF THE FIN WHALEAORTA Robert E. Shadwick and John M. Gosline, Department of Biology, University of Calgary, Calgary, Alberta, and Department of Zoology, University of British Columbia, Vancouver, B.C. Canada. We investigated the morphological and biomechanical properties of the aorta of the Fin whale Balaenoptera physalus to determine if any mechanical adaptations were present which might be important in hemodynamics, particularly with respect to long periods of diastole during diving. The most striking feature was the very large and bulbous aortic arch, which had far greater distensibility than the smaller diameter thoracic and abdominal aortae. In vitro inflation tests showed that over the expected physiological pressure range of 10 to 18 kPa the aorta would transiently store 60L of blood, while Measurements of stress-strain the thoracfc aorta would take only 1.6L. relationships and incremental elastic modulus indicated that the arch was more extensible, less non-linear and less stiff than the rest of the aorta. Pressure wave velocity was calculated as 6.4 m/s in the arch and 17 m/s in the thoracic and abdominal aortae. The elastin content was 39% in the arch and 25 x in the thoracic aorta. The aortic arch in the whale appears to be adapted to provide a substantial ‘Windkessel’ effect in the arterial circulation.
MECHANICAL PROPERTIES OF THE TOAD AORTA -IN VIVO AND -IN Carol A. Gibbons and Robert E. Shadwick Department of Biology, University of Calgary, Calgary,
VITRO Alberta,
Canada
The Arterial mechanical properties are important determinants of hemodynamics. mechanical properties of the toad aorta were studied by inflation tests of vessel The stress-strain curves had a non-linear “J” shape, similar to segments -in vitro. Stiffness increased with the degree of distention, and those described for mammals. the incremental modulus increased dramatically with pressure, having values comparable and aortic diameter pulses were also to those for mammals. In vivo pressure, flow, measured. Pressure-flowrelationships in transmission line systems are characterized The toad was found by wave propagation effects such as reflection and attenuation. Because of its short arterial tree, it is to have a low resting heart rate of 0.6 Hz. possible to represent it by a simpler Windkessel model, where the aorta acts as an The impedence spectrum had a elastic resevoir to the stiffer vascular resistance. sharp initial decrease and showed no detectable oscillations, and the pressure pulse showed no change in shape and little attenuation when propagated through the aorta. The pressure pulse was transmitted from the heart to the iliac bifurcation in 0.08 set or 52 of the cardiac These results support the idea that the toad aorta has cycle. suitable mechanical properties to function as a Windkessel in the circulatory system-