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Biomedical subjects

R F Appleyard

Publications and source records attributed to R F Appleyard.

21 records · Page 2Linked to original sources

Bench coronary angiography: a potentially useful method to assess coronary artery disease in the older donor heart without catheterization laboratory angiography.

To assess the diagnostic accuracy of ex vivo coronary artery arteriography, 12 sheep hearts were harvested, after random multiple coronary occlusions were created. The hearts were radiographed either in the flat (n = 6) or upright suspended (n = 6) position with the aorta cross-clamped. The aortic root was cannulated with an 18-gauge needle and flushed with cold normal saline solution. Five milliliters of iodinated contrast media was injected under constant hand pressure, and angiographic views were taken with a conventional, portable x-ray machine. The aortic root was then immediately flushed with normal saline solution under constant pressure to minimize contrast contact with the vascular endothelium. Total elapsed time including film development was 7 to 10 minutes. In hearts that were radiographed lying flat, a ventriculogram was obtained because of aortic incompetence. In hearts suspended in the upright position, normal coronary anatomy and previously placed coronary occlusions were easily detected in every heart that was read blindly by angiographers. To assess the effects of the contrast media on ventricular performance, five rabbit hearts were harvested and mounted on a Langendorff apparatus for functional analysis at controlled left ventricle volumes. Diastolic and systolic left ventricular pressures were unaffected by the dye injection. This simple and rapid method to evaluate coronary anatomy of the donor heart could be potentially useful in the assessment of older donor hearts in the operating room, thus increasing the volume of donor hearts available for transplantation.

Animals↗

Ischemic injury before heart transplantation does not cause coronary arteriopathy in experimental isografts.

In this study we investigated whether the duration of ischemia before heart transplantation was related to coronary arteriopathy. Heterotopic cardiac isografts were done in 24 Lewis rats. Group 1 hearts (n = 4) were transplanted immediately after harvesting. Hearts in groups 2 (n = 8), 3 (n = 6), and 4 (n = 6) were implanted after preservation at 4 degrees C for 1, 2, or 3 hours, respectively. No immunosuppressive drugs were given. After 120 days, grafts were removed and evaluated by means of light microscopy for coronary artery intimal proliferation. Minimal intimal thickening was noted throughout, and no differences among the groups were found. Pretransplant ischemia in the absence of other factors does not cause coronary arteriopathy after heart transplantation.

Abdomen↗

Thromboxane A2 mediates reperfusion injury after heart preservation.

To assess the role of the eicosanoid thromboxane A2, a potent vasoconstrictor and platelet activator, in reperfusion injury after heart preservation, donor rats (n = 18) were anesthetized, and their hearts were rapidly excised, arrested with cardioplegic solution, and fitted with a left ventricular balloon. Seven hearts were subjected to 45 minutes of ischemia at 15 degrees C, simulating implantation, (group 1) during which the carotid and jugular vessels of support rats were cannulated for ex vivo blood reperfusion. Remaining hearts were preserved in 4 degrees C saline solution for 3 hours followed by 45 minutes at 15 degrees C (group 2, n = 11). Before reperfusion of group 2 hearts, support rats received either vehicle (group 2a, n = 6) or thromboxane A2 receptor antagonist SQ29548 (0.2 mg/kg) (group 2b, n = 5). After 1 hour of reperfusion, left ventricular peak-systolic pressure and end-diastolic pressure were measured in all hearts at incremental ventricular volumes. The slope of the peak-systolic pressure-volume relation and the volume-axis intercept of the end-diastolic pressure-volume relation were also measured. No significant differences were noted in mean peak-systolic pressure, at any left ventricular volume, nor slope of the peak-systolic pressure-volume relation between groups, indicating that neither preservation nor SQ29548 treatment affected systolic contractile performance in this model. Through all left ventricular volume, however, end-diastolic pressure was significantly lower (p < 0.05) in group 2b compared to group 2a, and overall did not differ significantly from group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗