To accomplish isolation and removal of a substance from a vasculature, a catheter is employed to occlude a vessel of the vasculature. The substance is thus isolated in the vasculature and can be removed. In this way, the substance is removed before entering other parts of the circulatory system. This method is applicable to removal of contrast from the coronary sinus shortly after injection of the coronary arteries with the contrast. The method substantially minimizes or avoids renal dysfunction caused by angiographic procedures in which contrast must be injected. Such angiographic procedures are often performed during intervention procedures. This method substantially prevents circulation of the contrast to the kidneys where it could otherwise cause renal dysfunction or failure. The apparatus for implementation of the method is also disclosed.