**4. Preclinical study and animal trials**

Historically, most studies of revascularization have been based on and reported according to angiographic criteria. Some patients with significant arteriosclerosis of the heart are not amenable to revascularization of a coronary artery because they have a combination of microangiopathy and significant macroangiopathy. Therefore cardiac surgeons developed the technical approachof venous revascularization. Several systematic reviewshave beenconduct‐ edinanattempttodefine the exactrole of animalmodels asplatforms forfuturehumantherapy [9-12].We investigated the benefit of arterialization of a cardiac vein under these circumstan‐ ces in some animal models [13] which indicate retrograde venous revascularization is possi‐ ble and improves cardiac function in a state of acute ischemia so we could find its way into practical use in coronary heart surgery. In experimental studies in a variety of animals and in human clinical studies, retroperfusion of the coronary sinus has been used to improve myocar‐ dial perfusion and postischemic systolic and diastolic function in many surgical procedures. In addition, animal trials, mostly involving sheep, dogs and pigs showed that arterialization of cardiac veins decreases infarct size as well[11,14]. These animal models are likely to be useful for pre-clinical evaluation of the functional effects of surgical therapy.
