대동맥 차단 및 우회에 따른 혈역학 변화 -실험연구-

초록

Background: Cross-clamping the thoracic aorta is accompanied by dramatic changes in both proximal and distal hemodynamics. Although many studies focusing on the hypoperfusion effects distal to a clamp have been reported, only a few have noted derangement of the proximal hemodynamics caused by the abrupt elevation of preload and afterload. The purpose of this study was to determine the effects of simple aortic cross-clamping on the hemodynamics of the proximal cardiovascular system and to compare them with those of a shunt bypass. Material and Method: Hemodynamic changes were examined in a canine model of descending thoracic aortic surgery. Sixteen mongrel dogs (19~25 kg) were randomly divided into two groups: (1) a simple clamping group (CLAMP, n=7) and (2) a clamping with heparin-coated shunt group (SHUNT, n=9). Parameters observed were the proximal and distal blood pressures, heart rate, left atrial pressure, carotid blood flow, and cardiac output. Each parameter was measured serially and compared before clamping (baseline), immediately after clamping, 30 minutes after clamping, and after declamping. Result: In the CLAMP group, proximal pressures increased abruptly after clamping—from 117±15 to 177±17 mmHg in systole, from 82±13 to 129±16 mmHg in diastole, and from 96±11 to 147±14 mmHg in mean (p<0.001). The distal aorta lost its pulsation with a mean pressure of 20±1.5 mmHg. The heart rate decreased from 125±23 to 103±20 (p<0.05). The left atrial pressure increased from 8±2 to 14±2 mmHg (p<0.05), and the carotid blood flow increased from 120±58 to 291±131 ml/min (p<0.05). In the SHUNT group, no significant changes were observed in any of the parameters either after clamping or declamping (p=NS), and the distal aorta maintained its pulsatility with a mean pressure above 70 mmHg during the entire clamping period. In both groups, the carotid blood flow showed a positive correlation with the proximal pressures and the left atrial pressure, and was inversely correlated with the heart rate. Conclusion: Shunt bypassing may reduce the deleterious effects of proximal hypertension and distal hypoperfusion during aortic cross-clamping. We conclude that a shunt bypass is a safe mechanical adjuvant in descending aortic surgery.

키워드