Limb ischemia after EVAR: an effect of the obstructing introducer?

To evaluate the splanchnic and limb metabolic effects of open repair (OR) of abdominal aortic aneurysms (AAA) versus endovascular aneurysm repair (EVAR) in a pilot study utilizing microdialysis.

Nine AAA patients (8 men; mean age 74 years, range 61-85) were treated with EVAR and 9 had an OR (5 men; mean age 70 years, range 55-85). In the EVAR cases, which were performed percutaneously, the external iliac artery was obstructed by the introducer to a mean functional stenosis of 70% (52%-100%). Catheters for microdialysis were placed subcutaneously above the ankle of the right leg and freely in the abdominal cavity to measure the levels of lactate and pyruvate. The lactate/pyruvate ratio was calculated as a measure of ischemia. Measurements started at the end of surgery and continued for 2 days. Mean values were compared using the Mann-Whitney U test.

The mean value of intraperitoneal lactate during the first day after EVAR was 1.5+/-0.7 mM versus 2.6+/-0.8 mM after OR (p = 0.019). The lactate/pyruvate ratio was 10.2+/-2.2 after EVAR and 12.3+/-2.6 after OR (p = 0.113). Leg lactate mean values were 4.2+/-2.0 mM after EVAR versus 1.8+/-0.6 mM after OR (p<0.001). The lactate/pyruvate ratio was 20.1+/-8.3 for EVAR and 13.7+/-3.3 for OR (p = 0.040). These differences between EVAR and OR continued for the second day.

Intraperitoneally, metabolism was slightly increased after OR; however, it was not suggestive of splanchnic ischemia. Leg findings reflected a more extensive ischemia after EVAR over 48 hours, which was a somewhat unexpected finding that may be related to the introducer's impact on blood flow to the limb during the intervention. Although no clinical consequences were recorded, the finding suggests some benefit of minimizing as much as possible the time of reduced perfusion to the limb.