The risk of paraplegia associated with thoracic aortic cross-clamping is high even when various methods of spinal cord protection are used. In this study prostacyclin 12 (PGI2) was selected as an agent to reduce the spinal cord injury because of its vasodilator, antiaggregant, and cytoprotective properties.Twelve dogs underwent sixty-minute aortic occlusion. Six dogs received PGI2 whereas the other 6 did not (controls). PG12 administration was started at a rate of 5 ng/kg/minute five minutes before aortic occlusion. This dosage was increased to 25 ng/kg/minute during aortic occlusion. PGI2 at a dosage of 5 ng/kg/minute was maintained for a period of five minutes after the aortic occlusion was released.Three dogs in the control group were paraplegic. There were no paraplegic dogs in the PGI2 group. Distal aortic perfusion pressure was 31 ±6 mmHg in the PGI2 group and 22 ±3 in the control group (P < 0.008).As a result of this study the authors conclude that PGI2 is a valuable agent for decreasing the risk of spinal cord injury during thoracic aortic cross-clamping lasting sixty minutes.
Eighteen rabbit hearts were arrested for 3 hours with cardioplegic solution at 4°C, followed by reperfusion with oxygenated perfusion solution at 37°C for 2 hours. Six control hearts received no drug during arrest or reperfusion (group 1). Six hearts received 3 mg•L -1 aminophylline during the arrest period (group 2). Six hearts received 3 mg•L -1 aminophylline during the reperfusion period (group 3). Effects of aminophylline were evaluated in terms of the pressure-volume relationship, coronary flow, myocardial oxygen extraction, and lactate release before cardioplegic arrest and after 1 and 2 hours of reperfusion. End-diastolic pressure at constant volume after 2 hours of reperfusion was 19 ± 2.63 mm Hg in group 1, 14 ± 1.7 mm Hg in group 2, and 19 ± 2.55 mm Hg in group 3 (p < 0.05 for group 2 versus groups 1 and 3). End-systolic pressure at constant volume after 2 hours of reperfusion was 81 ± 3.55 mm Hg in group 1, 90 ± 2.95 mm Hg in group 2, and 84 ± 3.47 mm Hg in group 3 (p < 0.05 for group 2 versus groups 1 and 3). Oxygen extraction was significantly higher and release of lactate was significantly lower in group 2 compared to groups 1 and 3. The results indicate that aminophylline administration during cardioplegic arrest improved systolic and diastolic function and had a beneficial effect on metabolic recovery.
This study was planned to show th e effect of retroperfusion and intraaortic ba lloon pumping (lABP) on myocardial hem odynamic recovery. Twelve dogs ente re d thi s study. Half ofthem received IABP and coro na ry sin us retr operfusion (CSPR) combination (Group II) a nd the remaining received IABP alone (Group I). Left a nte rior descending artery was occluded for a peri od of three hours. 15 min utes aft er occlusio n IABP and IABP + CSRP wer e initia ted. The aver age ca rdiac output was 1.41 ±0.18 Ll min in th e gro up I and 1.72± 0 .24 Umin in the gr oup II (p < 0.03) after 3 hours of occlusio n. Mean a rte rial pr essure was 82.1 ± 4.8 mmHg in th e group I and 89 .7 ± 2.6 mmHg in th e gro up II (p < 0.03). On th e basis of this stu dy it was conclud ed that CSRP + IABP could be an alt ernative treatment to IABP alone during the acutely developing ischemia.
Ten dogs underwent 60 minutes of aortic occlusion; 5 received enoximone 10 µg·kg -1 ·min -1 and the other 5 served as controls. Distal and proximal aortic pressures were measured during the procedure. Neurological status was assessed after 72 hours. Spinal cord specimens were taken for electron microscopy. During aortic occlusion, cerebrospinal fluid pressure was 17 ± 3 mm Hg in the control group and 14 ± 4 mm Hg in the enoximone group, while distal aortic pressure was 15 ± 4 mm Hg in the control group compared to 47 ± 6 mm Hg in the enoximone group (p < 0.001). Four dogs in the control group suffered paraplegia but there was no paraplegia in the enoximone group (p < 0.01). Electron microscopy scores indicated significantly less ultrastructural damage (p < 0.01) in the enoximone group (2.73 ± 0.79) than in the control group (7.67 ± 0.89). It was concluded that enoximone was effective in reducing the risk of spinal cord injury during aortic crossclamping.
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