Pulsed electrical stimulation for control of vasculature: temporary vasoconstriction and permanent thrombosis.

A variety of medical procedures is aimed to selectively compromise or destroy vascular function. Such procedures include cancer therapies, treatments of cutaneous vascular disorders, and temporary hemostasis during surgery. Currently, technologies such as lasers, cryosurgery and radio frequency coagulation, produce significant collateral damage due to the thermal nature of these interactions and corresponding heat exchange with surrounding tissues. We describe a non-thermal method of inducing temporary vasoconstriction and permanent thrombosis using short pulse (microseconds) electrical stimulation. The current density required for vasoconstriction increases with decreasing pulse duration approximately as t(-0.25). The threshold of electroporation has a steeper dependence on pulse duration-exceeding t(-0.5). At pulse durations shorter than 5 micros, damage threshold exceeds the vasoconstriction threshold, thus allowing for temporary hemostasis without direct damage to surrounding tissue. With a pulse repetition rate of 0.1 Hz, vasoconstriction is achieved approximately 1 min after the beginning of treatment in both arteries and veins. Thrombosis occurs at higher electric fields, and its threshold increases with vessel diameter. Histology demonstrated a lack of tissue damage during vasoconstriction, but vascular endothelium was damaged during thrombosis. The temperature increase does not exceed 0.1 degrees C during these treatments. (c) 2007 Wiley-Liss, Inc.