**3.1. Operation**

**Cardiopulmonary Bypass** Once Aorta and right atrium is dissected, the heart can be arrested. Effective myocardial protection is essential in previously revascularized heart. Both antegrade and retrograde coronary perfusion are critical. Antegrade cardioplegia may not be effective for areas supplied by ITA, and may dislodge emboli from the atherosclerotic debris from the disease vein grafts. On the other hand, retrograde cardioplegia protects from embolization and removes debris from the retrograde flow. 11 Epiaortic ultrasound is performed to prior to aortic crossclamp to identify any aortic plaques. [12] Mild hypothermia is induced after patient is placed on CPB. When there is patent LITA, it is standard practice to dissect and clamp. However, if the dissection is difficult, moderate hypothermia with either fibrillatory arrest or systemic hyperkalemia can be used to arrest the heart. Manipulation of the graft should be

**Revascularization** If LITA or RITA was not used, this will be the first choice for conduit. When ITA is used to replace a vein graft, the old vein graft should be left in place and arterial vessel should be anastomosed to the same coronary vessel. [13] If the vein graft is ligated this may induce ischemia to the target vessel. If saphenous vein is used for conduit, distal anastomosis can be performed directedly to the native coronary artery or to the cuff of 0.5mm of old vein graft if no distal stenosis is present. Proximal anastomosis is performed in similar fashion; however, if there are minimal aorta that can be used for anastomosis, graft can be connected

If there is associated procedure such as aortic procedure or valve procedure, distal anastomosis is performed prior to valve procedure to avoid manipulation of the heart after the prosthesis is in place. When adding ITA graft to stenotic LAD vein graft, it is advised to leave the stenotic vein graft to avoid hypoperfusion, although there is a risk of distal embolization from the old

From Society of Thoracic Surgeon database, surgical coronary revascularization has evolved over the last decade, with reoperative CABG now uncommonly performed in contemporary practice. reoperative CABG dropped from 6.0% in 2000 to 3.4% in 2009. [14] Reoperative mortality is high in reoperative group, operative mortality declined from 6.1% in 2000 to 4.6% in 2009 despite the fact that patients now more frequently present with left main disease, myocardial infarction, and heart failure. In centers with large operative experience, reports have demonstrated consistently lower mortality. There is increasing evidence that the preemptive strategies discussed here may minimize technical and postoperative complication. [15] Patients also now present more frequently for urgent or emergent surgery and following previous PCI. They also now have a higher incidence of other comorbidities such as increased weight, diabetes, hypertension, hypercholesterolemia, renal failure, and cerebrovascular

Despite operating in patients with more complex coronary artery disease and greater medical comorbidities, there have been significant improvements in operative morbidity and mortality in this challenging population. The primary reason for increased mortality appears to be related to perioperative myocardial infarction (MI), due to graft injury, graft failure, inade‐

avoided until the heart is arrested since this can dislodge the debris.

to the previous proximal graft.

**2.3. Outcomes**

176 Artery Bypass

disease.

vein and competitive flow to the new graft.

Right coronary artery (RCA) is the most common vessel which coronary endarterectomy is performed. LAD endarterectomy is a technically complex procedure when compared to RCA endarterectomy due to the location and configuration of the septal and diagonal branches. LAD atherosclerotic core is narrow and delicate which increases the risk of disruption under tension. Unidirectional traction on the plaque can cause shearing off the branches. It is quite common that an extended arteriotomy or multiple arteriotomies are performed to achieve adequate plaque extraction. In cases where an extended arteriotomy is performed, the proximal third is used as the site of LITA anastomosis while the distal aspect of the vessel is reconstructed with a vein patch. In cases where 2 or more distinct arteriotomies are created, the LITA may be used for both sites as a separate graft; however, it is common practice that the LITA be used for 1 arteriotomy site and vein graft(s) used for the remainder. [18]

**Endarterectomy** Endarterectomy for a diffusely diseased coronary artery is used when 1-mm probe is not passed. It is often necessary to create long arteriotomy. After the coronary arteriotomy, an endarterectomy spatula was used to identify the plane of dissection and then to mobilize the plaque proximally and distally. A 1-mm probe was advanced gently through the plane of dissection to break away resistant adhesions. A combination of gentle traction on the plaque and countertraction on the adventitia is useful to extract the plaque. When proper distal tapering of the specimen was not achieved, the arteriotomy was extended distally for complete extraction of the plaque. The proximal end of the endarterectomy should be distal to the most proximal lesion, to avoid competitive flow through the native coronary artery, to the level of the first diagonal branch at most. The atherosclerotic plaque varies from soft to extremely calcified and adherent. This characteristic dictates the length of the arteriotomy inasmuch as adherent plaques cannot be removed easily through a limited arteriotomy to at least the distal two thirds of the length of the target. If this was the case, the arteriotomy was extended to allow for complete extraction of the atherosclerotic core.

tion which is known as porcelain aorta. The danger of applying cross clamp is associated with markedly increased incidence of cerebral or systemic embolism. The avoidance of multiple aortic manipulations is the key and strategy must be designed based on this principle.

Complex Coronary Artery Disease http://dx.doi.org/10.5772/55251 179

Atherosclerotic disease of the ascending aorta is becoming an increasing problem and is important to understand the prevalence of this disease entity. Mills and Everson reported 2.0% of unclampable aorta in their CABG population of 1735 patients. [25] Other reports have indicated its occurrence between 2-5% [26, 27]. Goto et al reported in their 463 patients undergoing CABG reported stroke rate of 10.5% in patients with severe atherosclerosis compared with 1.8% in normal or near-normal control patients. [28] The challenges in such

Due to its potential to modify surgical strategy, preoperative or intraoperative diagnosis of unclampable aorta is the key. Accurate diagnosis of aortic atherosclerotic disease is of para‐ mount importance. No diagnostic criteria have been established to date, and often unclamp‐ able aorta is diagnosed intraoperatively by manual palpation or epiaortic ultrasonography. Disease of the carotid artery and abdominal aorta, stenosis of LAD and age has been reported to be associated with unclampable aorta. [29] Given the predictors of atheromatous aortic disease are age, hypertension, diabetes, dyslipidemia, peripheral vasculopathy and diabetes

**Images- CXR, Cath, CT scan, TEE** Chest X-ray and cardiac catheterization images may demonstrate the presence of atherosclerosis but is not always sensitive. Routine use of screening CT scan in this high risk group is useful to prevent incidence of stroke. [31] CT scan without contrast will delineate the white calcium in clear contrast to the non-calcified aorta which will appear dark. Intraoperatively, epiaortic ultrasound is superior to manual palpation of the ascending aorta and to Transthoracic echocardiography (TEE) for detection of athero‐

**Epiaortic Ultrasound** Epiaortic ultrasound may reduce the frequency of neurological injury after surgery due to cerebral embolism by allowing for the identification and avoid atheroma at the site of cannulation and further manipulation. Introduction of epiaortic ultrasound was associated with reduction in prevalence of stroke from 1.2% to 0.7% in retrospective review of 8547 patients undergoing CABG surgery. [33] With this, epiaortic scanning now appears to be

Management of this complex disease remains a major dilemma. Several techniques including aortic graft replacement, aortic endarterectomy, no touch technique and off-pump bypass has

**Techniques Using Hypothermic Circulatory Arrest** Both Aortic graft replacement and

endarterectomy are performed using period of hypothermic circulatory arrest.

situation are to make the accurate diagnosis and operative strategy.

[30], screening for calcified aorta is recommended in these patient groups.

the gold standard in diagnosis of atherosclerosis in ascending aorta.

been described to cope with this difficult problem.

**4.1. Work up**

sclerosis. [32]

**4.2. Operation**

**Cardioplegia Flush** After complete extraction, retrograde cardioplegic solution was given to flush out any debris that may have embolized distally. A visible flow of retrograde cardioplegic solution through the diagonal and septal branches is indicative of successful endarterectomy.

**Vein Patch** The saphenous vein patch was applied to the endarterectomized vessel with a long arteriotomy and the LITA was then applied to either the middle of the vein patch or the proximal end of the arteriotomy or LITA onlay patch grafting was used for a relatively short arteriotomy after confirming that there was no tension on the graft.

**Myocardial Protection** Myocardial protection is achieved with combination of antegrade and retrograde blood cardioplegia. Retrograde cardioplegia is essential during endarterectomy as it allows for flushing of debris proximally, thereby minimizing the risk of myocardial infarction secondary to plaque emboli. Furthermore, retrograde cardioplegia serves a diagnostic purpose; brisk flow through the entire artery indicates complete plaque extraction.

**Postoperative Drug Regimen** Prevention of platelet aggregation and thrombus formation is crucial to prevent graft and native vessel occlusion. An aggressive protocol is generally required and includes intravenous heparin in the immediate postoperative phase as well as lifetime treatment with clopidogrel (with loading dose) and aspirin.
