**4.1. Work up**

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

**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

**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

**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

The risk of endarterectomy patients are higher compared to CABG alone. In some reports, long term patency is inferior to CABG, but in experienced hands operative mortality of 3.0% and 5-year survival of 87% can be achieved. [19] The most significant complication is periooperative MI after endarterectomy. It is significant higher compared to CABG alone including MI occurrence which occurs in 5-10%. [20] Multiterritory endarterectomy is associated with worse long term survival (64% 5-year survival and 36% 10-year survival), but this could be due to

LAD endarterectomy was intially reported with increased incidence of morbidity and mortality. [22 23] With technical modifications including LITA grafting with saphenous vein patch and LITA onlay patch grafting, the outcomes in this high risk group has significantly improved. [24] Endarterectomy provides good results and mainstay of the treatments for patients with severe diffuse coronary artery disease not amenable to PCI and traditional

The atherosclerotic involvement of the ascending aorta presents technical challenge in patients undergoing CABG. The degree of calcification ranges from isolated plaques to total calcifica‐

purpose; brisk flow through the entire artery indicates complete plaque extraction.

extended to allow for complete extraction of the atherosclerotic core.

arteriotomy after confirming that there was no tension on the graft.

lifetime treatment with clopidogrel (with loading dose) and aspirin.

**3.2. Outcome**

178 Artery Bypass

higher risk patient population. [21]

surgical intervention.

**4. Calcified aorta**

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

**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‐ sclerosis. [32]

**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 the gold standard in diagnosis of atherosclerosis in ascending aorta.

### **4.2. Operation**

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 been described to cope with this difficult problem.

**Techniques Using Hypothermic Circulatory Arrest** Both Aortic graft replacement and endarterectomy are performed using period of hypothermic circulatory arrest.

**•** Deep Hypothermia Deep hypothermia (18-20°C) should be attained on CPB. Following fibrillation of the heart, a left ventricular vent is placed.

**5. Transmyocardial laser revascularization**

candidates but have an ejection fraction below 20%.

have been performed in the United States. [44]

through hollow tubes to the epicardium.

diogram to avoid induction of arrhythmias.

**5.1. Operation**

starting inferiorly.

Transmyocardial laser revascularization (TMR) is one of the first described surgical procedures intended to treat severe diffuse CAD not amenable to CABG or PTCA in patients who have had previous percutaneous coronary interventions and/or CABG procedures. This severe coronary artery disease can lead to incomplete revascularization following CABG and is powerful independent perioperative adverse events. Indications for TMR include NYHA class III/IV symptoms refractory to medical treatment with coronary disease that is not amenable to revascularization. [38, 39, 40]TMR is generally contraindicated in patients who are candidates for revascularization or those who are not

Complex Coronary Artery Disease http://dx.doi.org/10.5772/55251 181

By inducing angiogenesis with a laser (carbon dioxide, holminumyttrium– aluminumgarnett), TMR has been shown to decrease the severity of angina symptoms compared to medical therapy. [41, 42] As such, the primary indication for TMR is persistent and disabling angina refractory to medical therapy. Owing to its success as sole therapy, TMR is used in conjunction with CABG. The safety and efficacy of TMR in this subset of patients has been well described; operative mortality and morbidity may be significantly less than CABG alone. [43] Since Food and Drug Administration (FDA) approval in 1998, over 20,000 TMR procedures

**Left thoracotomy and Heart Exposure** A left anterolateral thoracotomy is the incision of choice in patients undergoing TMR as the sole surgical procedure. The heart is exposed, allowing for the access to the anterior, apical, and posterolateral planes of the left ventricle. Careful attention must be paid to not injure the previous bypass grafts. LAD is identified and used as a landmark for the location of the septum. TMR is provided through a hand piece that delivers energy

**Choose type of laser** Type of Laser Only CO2 and Holmium-chromium: YAG lasers (Ho:YAG) are clinically approved for TMR. The result of any laser-tissue interaction is dependent on both laser and tissue variables. CO2 laser has wavelength of 10,600nm, whereas Ho:YAG laser has wavelength of 2,120nm. The laser is synchronized to occur on the R-wave of the electrocar‐

**Application of laser** Pulse energy of 20-30 J over 4 pulses per second creates 1-mm channels in the myocardium that can be visualized with a transesophageal echocardiogram. Using the CO2 laser, channels are first created at the base of the heart and are separated from each other by 1 cm to the apex of the heart starting inferiorly and working superiorly to the anterior surface of the heart. As there is some bleeding from the channels, gravity will keep the field clean by

It should be noted that TMR does not provide any added benefit to areas of myocardium that are scarred and have no viability. TMR on the transmural scar will not only be non-beneficial,


**No touch Technique** No touch technique described by Suma et al can be used [34]. In this instance, CPB is established between right atrium and aortic arch or femoral artery. Left ventricular vent is placed. Aortic cross clamping and cardioplegia delivery was avoided. Ventricular fibrillation was induced while target was occluded using elastic stitches. Pedicled artery graft is used for anastomosis. In case the saphenous vein is used, it is anastomosed to the artery graft or to the ascending aorta where calcification is spared.

**Off-pump bypass** Off-pump bypass can be used in case arch and femoral artery is calcified as well. In this case, all arterial revascularization is performed using in situ internal thoracic and radial artery. Y grafts are created to internal thoracic artery if radial artery is used.

#### **4.3. Outcome**

Aortic endarterectomy and aortic graft replacement provides opportunity to revascular‐ ize the coronary artery and eliminate danger of systemic emboli. It is reported to be performed safely, [35, 36] but these procedures do add complexity and risk due to the circulatory arrest.

No touch technique and off pump technique provides theoretical benefit to the proce‐ dure, but has not been able to provide definite superiority. Off pump technique offers inferior possibility of complete revascularization especially to the lateral branches of circumflex artery. On the other hand, no touch technique still requires insertion of the arterial cannula which can predispose to systemic and cerebral emboli. Gaudino et al compared these two techniques in 211 unclampable aorta cases and reported no touch technique had greater incidence of neurological complications, renal insufficiency, and stay in the intensive care unit and hospital. However, at midterm follow-up, more patients of the off pump group had ischemia recurrence. [37] Stroke rate was 2.3% and inhospital mortality was 2.8% in this study.
