*5.2.2. Unique surgical procedure – Blood flow limitation*

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

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 the ischemic myocardium through the cardiac veins [27].

**Figure 4.** Flow-limited CVBG

**5.2. Surgical procedure**

**Table 1.** Characteristics of patients

Coronary angiography

282 Artery Bypass

*5.2.1. General surgical procedure*

coronary artery was bypass grafted.

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

Group 1 N=17

Gender (M/F) 11/6 14/7 Age (years) 46.1±6.2 45.9±5.7 Hypertension (yes/no) 7/10 9/12 Diabetes mellitus (yes/no) 10/7 11/10 LVEF 0.52±0.09 0.52±0.11 LVEDD (mm) 52.7±5.1 51.9±5.2

Double-vessel lesions 7 9 Triple-vessel lesions 10 12

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

Group 2 N=21

#### **5.3. Follow up**

Three months after discharge, all the patients in group 1 had no preoperative symptom. Myocardial ischemia was not found by electrocardiogram in group 1. Postoperative angina was found in eight cases of group 2 and electrocardiogram showed inferior wall myocardial ischemia. There was significant difference between the two groups (P <0.05). Cardiac function was improved to class I (P <0.001), LVEF was increased to 0.60±0.08 (P <0.001) in group 1 and 0.56±0.10 (P <0.001) in group 2 which showed no preoperative differences and the postopera‐ tive LVEF of group 1 was superior to group 2 while there was no significant difference between these two groups. LVEDD decreased to (48.1±3.4) mm (P <0.001) in group 1 and (47.2±3.5) mm (P <0.001) in group 2. Patients underwent physical examination and echocardiography in our outpatient clinic periodically after discharge. These data were compared with the patients' preoperative variables. Several examination of myocardial nuclide imaging, coronary angiog‐ raphy (41 months postop.) and CT scanning (5 years postop.) were carried out (Figure 5).

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

Surgical Treatment for Diffuse Coronary Artery Diseases

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

285

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

long-term experiments, effective selected area perfusion had been achieved.

each graft with flowmeter after anastomosis in order to keep vessel grafting patent.

prognosis may be expected with more precise anastomosis.

Cheng-Xiong Gu, Yang Yu and Chuan Wang

**Author details**

Beijing, China

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

6 Department of Cardiac Surgery, Beijing An Zhen Hospital, Capital Medical University,

**Figure 5.** follow-up CT scanning data of CVBG.
