**5.1. Data analysis**

findings led them to state that there are communications between the venous and arterial sides of the circulation which, in the dead specimen, allowed blood flow in a retrograde direction. The Beck II procedure afterwards consisted of a free vein graft from the aorta to the coronary sinus, with a second operation 2 to 3 weeks later to ligate the coronary sinus, which reported remarkable success in attempts to revascularize the heart. The effectiveness of reversing flow in the coronary venous system had been debated and this operation was gradually abandoned because of related mortality of 26.1% and development of CABG. However, CABG was soon discovered to have its own limitations, particularly in patients with diffuse atherosclerotic lesion and tiny coronary arteries. Arterialization of coronary veins therefore regained its appeal. Arealis and colleagues brought forth selective CVBG in 1973 which was made only for part of ischemic myocardium, while normal reflux was kept for the rest myocardial veins. Great cardiac vein parallel to LAD and middle cardiac vein parallel to PDA were selected as goal vessels. Eventually an ample report of CVBG animal trial was published by Dr. Hochberg in 1979which indicated CVBG's advantages, such as perfusion all layers of the myocardium, especially the subendocardium – the crucial layer of myocardial muscle[2]. However, this mechanism had been studied at the experimental level because its relatively high clinical mortality and was only theoretic until CVBG technique developed in the recent years.

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

There is no doubt that for patients with surgical triple-vessel coronary disease and a severely diseased left main artery, CABG appears to be preferable [15]. Despite constant advances in surgical and interventional therapy of coronary artery disease, there remains a group of

for pre-clinical evaluation of the functional effects of surgical therapy.

**5. Surgical option – CVBG versus traditional CABG**

**4. Preclinical study and animal trials**

280 Artery Bypass

From March 2004 to August 2010, patients with diffuse right coronary lesions were studied retrospectively and divided into two groups (Table1). Informed consent and ethical review committee approval were obtained. Group 1 included seventeen patients who underwent selective CVBG during OPCAB while group 2 included twenty-one patients without right coronary artery surgical therapy. Group 1 included eleven male cases (64.7%), the mean age was (46.1±6.2) years, seven hypertension cases (41.2%) and ten diabetes mellitus (58.8%) cases were involved. The case number of cardiac function from II–IV grade was eight, eight, and one respectively. Left ventricular ejection fraction (LVEF) was 0.52±0.09 and left ventricular end diastolic diameter (LVEDD) was (52.7±5.1) mm. Group 2 included fourteen male cases (66.7%), the mean age was (45.9±5.7) years, nine hypertension cases (42.9%) and eleven diabetes mellitus (52.4%) cases were involved. The case number of cardiac function from II–IV level was twelve, seven, two respectively. LVEF was 0.52±0.11 and LVEDD was (51.9±5.2) mm. There was no significant difference between the two groups (*P* >0.05). All the patients had angina pectoris symptom before operation. It was indicated by electrocardiogram that all the cases with old myocardial infarction had obvious ST-T changes. Coronary angiography showed that seven cases had double-vessel lesions and ten cases had triple-vessel lesions in group 1; nine cases had double-vessel lesions and twelve cases had triple-vessel lesions in group 2. Right coronary artery of all the patients took on diffuse lesions with vascular diameter <1 mm and length >20 mm. It was shown by vascular ultrasound examination that blood flow in bilateral mammary artery was smooth and vascular diameter >2 mm; and left subclavian artery was not narrow.

OPCAB was performed with an average of 3.6 grafts per patient, group 1 being (3.3±1.1) grafts and group 2 being (2.2±1.6) grafts respectively. These patients discharged eight to fourteen days after the operation. Determination of blood flow was made for eleven cases in group 1 and thirteen cases in group 2 which were (81.47±32.65) ml/min and (76.82±28.36) ml/min in trunk of IMA, (32.52±18.82) ml/min and (28.12±16.71) ml/min in trunk of left IMA, (39.63 ±19.02) ml/min and (35.92±18.34) ml/min in trunk of right IMA. The both groups had no death. Tracheal cannula was pulled out on the date of operation or one day after operation. Low-dose positive inotropic drugs were used as assistance for four cases postoperatively. All the patients had no brain complication and no infection of sternum and mediastinum.


*5.2.2. Unique surgical procedure – Blood flow limitation*

the ischemic myocardium through the cardiac veins [27].

**Figure 4.** Flow-limited CVBG

Venous arterialization occurs when a vein segment is transposed as a bypass graft into the arterial circulation, and atherosclerosis is a common feature of autogenous vein bypass grafts resulting in their long-term failure [18-20]. Arterial pressure-induced distension is thought to play a major role in the wall thickening of vein grafts, which may in turn favor atherosclerotic complications [21,22]. Reduction of the wall distension by perfusion pressure reduction using blood flow limitation protected the vein grafts from atherosclerosis, possibly as a result of the

Surgical Treatment for Diffuse Coronary Artery Diseases

http://dx.doi.org/10.5772/54416

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Saphenous vein was commonly used to complete CVBG. After harvesting, meticulous care should be taken to avoid distention of the vein graft. An infusion pressure of no more than 100 mmHg is recommended for minimal endothelial damage [25]. In our previous study and emerged that ischemia and infarction of myocardium would happen if the blood flow in grafting vessel was less than 50 ml/min. The blood was delivered into the cardiac veins by the native arterial pressure, However when intravascular pressure reached 60 mm Hg (1 mmHg = 0.133 kPa) or higher, the risk of complications would increase such as myocardial edema and even intramural hemorrhage and so on [26]. In this case, we used to ligate the vein graft to 1.5 to 2 mm in diameter with two interrupted silk lines to control blood flow (Figure 4). It has been reported that infarct size can be reduced by which arterial blood is delivered retrogradely to

decrease in wall thickening that occurred in response to arterialization [23,24].

*LVEF*: Left ventricular ejection fraction; *LVEDD*, left ventricular end diastolic diameter.

**Table 1.** Characteristics of patients

#### **5.2. Surgical procedure**

#### *5.2.1. General surgical procedure*

In group 1, standard median sternotomy incision was applied for the exposure of the heart under general anesthesia. Bilateral IMAs were harvested as longer as possible and usually cut proximally at the starting position from subclavian artery and distally on the level of Xiphoid. Surrounding tissues of IMA were desected and removed so as to ensure enough length of IMA (generally 18–25 cm). The free right IMA was anastomosed with left IMA to form a bifurcation as "Y" type. The anastomotic position on the LIMA should be determined according to its length and the distance from the bypass grafting anastomosis between LIMA and LAD or diagonal. The position was usually selected at the location of 3–4 cm proximal to the first anastomotic site of left IMA, and 8-0 prolene suture was utilized in end-to-side anastomosis between two mammary arteries. Subsequently, CABG was carried out on beating heart. Left IMA was anastomosed to left anterior descending artery (LAD) and then right IMA was sequentially anastomosed with diagonal branch and circumflex artery (obtuse marginal and posterior branch of the left ventricle). Then the end of middle cardiac vein proximal to heart was blocked with 6-0 prolene suture so that blood can not reflow to coronary sinus in normal way. Finally, end-to-side anastomosis between middle cardiac vein parallel to right coronary post descending artery (PDA) and right IMA was performed with 8-0 prolene suture. When all the vessels were anastomosed and blood circulation was stable, blood flow of grafting vessels was determined by Transonic H1311 flowmeter (Transonic Systems, Inc., Ithaca, NY, USA). Incision was carefully washed before closing chest. In group 2, no branch of the right coronary artery was bypass grafted.
