Experimental study of hemodynamics in procedures to treat access-related ischemia

Abstract

This experimental study investigated the hemodynamic effect of corrective procedures for arteriovenous access-related ischemia in pulsatile flow. Silicone models of an emulated tapered and bifurcated arterial tree of the upper arm and forearm were integrated into a pulsatile flow circuit. The model allowed the study of hemodynamics of simulated arteriovenous fistulas, including collateral circulation, as well as the study of different simulated procedures to improve distal hypoperfusion. Flow rates and arterial pressure were measured simultaneously during simulation of corrective procedures and correlated to hemodynamic values of uncorrected ischemia. It was demonstrated that the more proximally localized an arteriovenous anastomosis is, the higher the distal arterial pressure will be at any given fistula flow. Reduction of the fistula flow resulted in a significant improvement of distal perfusion. Ligation of the artery distal to the arteriovenous fistula to prevent retrograde flow increased the distal perfusion only slightly in simulated ischemia. In contrast, the simulated corrective procedures of distal revascularization interval ligation and proximalization of arterial inflow resulted in a significant improvement. The most significant improvement of distal perfusion was observed with the simulated proximalization technique, whereas the effect of distal revascularization technique was less pronounced at higher fistula flow. Arterial ligation after distal revascularization increased the distal pressure only by 10%. A more centrally localized arteriovenous anastomosis and a reduction of fistula flow significantly increase distal perfusion. The procedure of proximalization of arterial inflow is at least equivalent to the distal revascularization interval ligation technique for the correction of distal ischemia, but does not sacrifice a patent axial artery. The moderate effect of interval ligation of the latter technique should be evaluated by further intraoperative measurements.