Neutrophil-Related Myocardial Depression Following Removal of Infrarenal Aortic Cross-Clamping

Purpose: A significant reduction in cardiac function following aortic declamping has been recognized and is associated with reperfusion of the ischemic lower torso. We hypothesized that reperfusion of the ischemic lower torso should activate neutrophils, resulting in myocardial depression. To test this hypothesis, we measured cardiac contractility during and after one hour of infrarenal aortic cross-clamping in neutrophil depleted animals. Methods: Adult mongrel dogs (n=17) were divided into three groups. In 12 animals, the infrarenal abdominal aorta was clamped for one hour with (neutrophil depleted + clamp group: n=6) and without (clamp group, n= 6) neutrophil depletion. The neutrophils were depleted prior to aortic clamping with a leukocyte removal filter. The neutrophil counts fell from 4233±508/mm^3 to 867±71/mm^3, approximately 20% of the baseline starting value. In the control group (n=5), the abdominal aorta was not clamped. Results: In the clamp group, the cardiac output decreased to 70+3% and 68ｱ3% of the baseline level at 1 and 2 hours, respectively, after declamping. The dp/dt of the left ventricle was reduced 56±10% and 51±8% of the baseline, and Emax also decreased to 66±6% and 62±5% of the baseline at 1 and 2 hours, respectively, after declamping. These cardiovascular changes were significantly attenuated in the neutrophil depleted + clamp group. The cardiac output was depressed to 83±3% of the baseline value at 2 hours after declamping in the neutrophil depleted + clamp group, which was significantly higher than that in the clamp group. Left ventricular dp/dt and Emax did not decrease 1 hour after declamping in the neutrophil depleted + clamp group, but did decrease significantly depressed to 81±4% and 78±8%, respectively 2 hours after declamping. These values were significantly better than those in the clamp group. There was no significant change in the control group throughout the study in any variable. Conclusion: In conclusion, reperfusion of the ischemic lower torso of dogs produced myocardial depression. Post-declamping cardiac depression appears to be closely related to neutrophil activation.

腎動脈下腹部大動脈

大動脈遮断

再灌流障害

心機能