In patients treated with IV sclerosant foams, circulating gas bubbles reach the right heart and are usually filtered out by the lung. In patients with right-to-left (RL) shunts, bubbles may enter the arterial circulation. It is unknown whether these bubbles can cause microvascular infarctions. This study investigates whether patients with MCA bubbles detected during treatment with a proprietary polidocanol microfoam (MF) experience subclinical events. Patients with SFJ incompetence and great saphenous vein (GSV) reflux (CEAP 3-5) who are ≤ 60 years and free of arteriovascular disease can be enrolled in this IND study. Transcranial Doppler (TCD) with agitated saline contrast assesses presence of RL shunt prior to treatment. GSV incompetence is treated by injection of a proprietary polidocanol MF formulated with a gas mixture designed to maintain physical MF characteristics while accelerating bubble absorption, and dispensed via a canister system controlling density and bubble size (the Varisolve procedure). During and after the procedure patients undergo TCD monitoring of the MCA for 1 hr. Patients with detectable MCA bubbles receive intensive surveillance for microinfarction including MR with diffusion-weighted imaging at 1, 7 and 28 days, neurological exam, perimetry, and cardiac markers. TCD and MRI are assessed by blinded central reviewers. Recruitment will continue until 50 patients with MCA bubbles during the procedure are evaluated (projected Spring 2008). In patients with GSV incompetence screened for enrollment, RL shunts are diagnosed in 1/3 of patients. In shunt-positive patients treated with polidocanol MF, 90% have detectable MCA bubble emboli during the procedure, but the number of bubbles is low (maximum 13 bubbles in patient with Grade V shunt). After evaluation of 11 patients with MCA bubbles, none have developed new MRI lesions, neurological or visual field abnormalities, or elevated cardiac markers. Patients undergoing foam sclerotherapy are commonly exposed to gas bubbles in the cerebral (arterial) circulation. A proprietary polidocanol MF with controlled density, bubble size and gas mix has not been associated with evidence of microinfarction.