arteriolar vasodilator arteriolar vasodilator arteriolar vasodilators are substances or medications that preferentially dilate arterioles. when used on people with certain heart conditions, it causes a phenomenon known as the cardiac steal syndrome. arteriolar vasodilators increase intracapillary pressure, which causes fluid to enter the tissues, leading to vasodilatory edema. arteriolar vasodilators include: hydralazine minoxidil nitroprusside