**6. Conclusion**

In the past few decades, there was an increase in the number of patients with coronary heart disease who were not eligible for standard procedures including CABG and percutaneous coronary angioplasty, and diffuse coronary atherosclerosis occupies 12%–30% of patients requiring further intervention [28]. Clinical trials investigating treatment with angiogenesis factors and gene therapy have been initiated, and new devices for creating cardiac arteriove‐ nous fistulas percutaneously have also been introduced [29-32]. Whereas injection of growth factors require an adequate arterial inflow, which is not often existent in the hearts of these "no option patients". New catheter devices to create a fistula between a coronary artery and the accompanying vein or, as performed in animal experiments, a coronary vein and the left ventricle, are difficult to handle, and hold all the risks of catheterization of a severely altered vessel [33]. Before that, small numbers of reports of the clinical application had published, so no remarkable conclusions can be yet drawn [34-37]. As the efficiency of these new methods awaits the evaluation of long-term trials, we think that some patients might benefit from the revival of an "old" procedure that is retrograde venous revascularization. In both short and long-term experiments, effective selected area perfusion had been achieved.

Despite the successful and widespread application of these revascularization procedures, a large number of patients are not good candidates for either angioplasty or surgery. These "nooption" patients frequently have diffuse coronary disease without a discrete target for angioplasty, stenting, or surgical bypass [33].In clinical application, we draw some experiences as follows. Blood flow of IMA is important to ensure perfusion of myocardium after bypass grafting which can be determined by preoperative vascular ultrasound examination and intraoperative testing. It is also important to make sure the diameter of each anastomotic incision 1.5 times as that of IMA in order to keep adequate blood flow. For the patients with coronary vessel less than 1.5 mm in diameter, it is necessary to use 8-0 prolene suture in case of anastomotic stricture. Attention should be focused on not damaging the posterior wall of middle cardiac vein while opening it, because the vascular wall of coronary vein is obviously thinner than that of coronary artery. The graft should be fixed to myocardium on both sides because IMA and middle cardiac vein are prone to twist due to different thickness of vascular wall. It is valuable to observe the difference of color on both segments of middle cardiac vein in the ligation. If red and dark are distinctive, it is indicated the ligation is definite. Otherwise it is possible that there is some residue blood flow [38]. It is useful to measure blood flow of each graft with flowmeter after anastomosis in order to keep vessel grafting patent.

CVBG surgery is indicated for both the relief of symptoms and the improvement of life expectancy in patients suffering from diffuse coronary heart disease [39-41]. We believe the selective CVBG should be considered in cases of coronary artery disease not amenable to traditional revascularization strategies [42-45]. Indications of selective CVBG include the patients with tenuous right coronary artery or diffuse lesions. It is possibly fit for the patients who need reoperation of CABG as well [46-48]. A substantial improvement in the long-term prognosis may be expected with more precise anastomosis.
