Coronary Artery Bypass Grafting: Surgical Anastomosis: Tips and Tricks

*Mohd. Shahbaaz Khan*

## **Abstract**

The definite feature of coronary artery disease is the focal narrowing in the vascular endothelium, and this leads to the decrease in the flow of blood to the myocardium. Atherosclerotic plaque is the main lesion. These patients can present with chest pain (angina or myocardial infarction) and need further workup noninvasively and invasively for the management. The main reasons for myocardial revascularization can be: (1) relief from symptoms of myocardial ischemia; (2) reduce the risks of future mortality; (3) to treat or prevent morbidities such as myocardial infarction, arrhythmias, or heart failure. Coronary artery bypass grafting (CABG) is the surgical technique of cardiac revascularization. In 1910, Dr. Alexis Carrel described a series of canine experiments in which he devised means to treat CAD by creating a "complementary circulation" for the diseased native coronary arteries. No clinical translation occurred at the time, but he was awarded the Nobel Prize in Medicine. Experimental refinements of coronary arterial revascularization, including the use of internal thoracic artery (ITA) grafts, were later reported by Murray and colleagues, Demikhov, and Goetz and colleagues in the 1950s and early 1960s. Dr. Rene Favaloro performed his first coronary bypass operation inMay 1967 with an interposed saphenous vein graft (SVG) and shortly thereafter used aortocoronary bypasses sutured proximally to the ascending aorta. The stenosed segment is bypassed using an arterial or venous graft. Left internal thoracic artery is the most commonly used artery, and long saphenous vein is the most commonly used vein for the coronary artery grafting to reestablish the blood flow to the compromised myocardium. This can be performed with or without the help of cardiopulmonary bypass machine and also with or without arresting the heart. These techniques are called as on-pump beating or on-pump arrested and off-pump beating coronary artery bypass grafting surgery. Distal and proximal anastomoses are usually performed in an end-to-side manner, but in the case of doing sequential grafting, side-to-side anastomosis is also performed proximal to the end-to-side anastomosis. In this chapter we are going to discuss the coronary artery bypass grafting tips and tricks in details.

**Keywords:** coronary artery bypass grafting, off-pump CABG, on-pump CABG, LIMA, RIMA, radial, RSVG, sequential grafting

#### **1. Introduction**

Coronary artery disease is a major cause of mortality and morbidity not only in the developed countries but also in developing countries. Over the last decade,

recommended for at least 1 year after PCI and CABG. Aspirin and clopidogrel combination is not recommended for stable angina as it is not superior to

3.Beta blockers—these medicines decrease the myocardial oxygen demand and improve exercise capacity. These are effective for stable angina, and dose should be adjusted to keep heart rate about 60/min at rest and less than

4.Calcium channel blocker—as beta blockers, these agents are also effective to treat stable angina. They act mainly by causing vasodilatation and reducing peripheral vascular resistance. The dihydropyridines (nifedipine, amlodipine, etc.) do not affect the SA or AV node conduction. Their mechanism of action is by dilating the coronary arteries and reducing the peripheral residence, thereby leading to the decrease in myocardial oxygen demand. On the other hand, non-dihydropyridines (verapamil, diltiazem, etc.) also affect the SA and

5.Nitrates—these are the coronary vasodilator agents. In the lower doses, they are venodilator and reduce the preload, while in higher doses they are also

6.Ranolazine—this is the selective inhibitor of the late influx of sodium, thus decreasing the myocardial contractility. It is usually used in combination with

7.Statins—these are hypolipidemic drugs that inhibit the HMG-CoA reductase

8.ACE inhibitors—they inhibit the angiotensin-converting enzyme. These are the class I recommendation for patients with chronic coronary artery disease with low LVEF (˂40%) or diabetic and a class II recommendation for patients

Although the term percutaneous coronary intervention refers to any therapeutic coronary artery intervention, it has become synonymous with the percutaneous coronary stent implantation. In the earlier days, bare metal stents were used, but over the last decades, drug-eluting stents are the most commonly used stents for PCI. PCI is performed in patients with stable coronary artery disease and also in

1.Moderate to severe stable angina with evidence of reversible ischemia.

2.High-risk unstable angina or ST elevation myocardial infarction (STEMI).

aspirin alone and increases the risk of bleeding [7].

*Coronary Artery Bypass Grafting: Surgical Anastomosis: Tips and Tricks*

AV nodes and decrease the oxygen demand.

enzyme and decrease atherosclerotic effect.

without these mentioned features [8].

**3. Percutaneous coronary intervention (PCI)**

beta blockers to treat angina.

settings of acute coronary syndrome.

4.Rescue PCI after failed thrombolysis.

**3.1 Indications for PCI**

3.Acute STEMI.

**81**

arterial dilators and thereby decrease the afterload too.

100/min with exercise.

*DOI: http://dx.doi.org/10.5772/intechopen.88932*

**Figure 1.** *Relationship between loss of cross-sectional area and diameter of the vessel.*

mortality with this disease has decreased, but still it accounts for approximately one-third of all the deaths in people over the age of 35 years. The American Heart Association reported that nearly 16.5 million people (20 years or more age) had coronary artery disease in 2017, with male predominance of 55% [1].

Coronary artery disease is the narrowing or occlusion of the vessel lumen due to arterial wall thickening caused by subintimal deposition of atheroma and loss of elasticity of the arterial wall. Atherosclerosis involves the proximal portions of the coronary arteries, specifically at the branching sites. In the beginning it only affects the flow reserve of the coronary artery, but as it advances, it affects the blood flow even at rest and leads to myocardial ischemia or infarction depending on the severity of the disease. This can be divided as supply ischemia (myocardial infarction and unstable angina) and demand ischemia (stable angina as during exercise, fever, emotional stress, etc.) [2]. The subendocardium is most vulnerable to myocardial ischemia due to the limited collateral blood flow. Therefore myocardial necrosis progresses from the subendocardium to the epicardium with continuing ischemia.

A 75% cross-sectional area loss (50% diameter) is considered an important but moderate stenosis, while a 90% cross-sectional area loss (67% diameter) is considered severe stenosis (**Figure 1**) [3].

There are three methods of treating coronary artery disease—medical management, percutaneous intervention, and coronary artery bypass graft surgery [4, 5].

## **2. Medical management of coronary artery disease**


recommended for at least 1 year after PCI and CABG. Aspirin and clopidogrel combination is not recommended for stable angina as it is not superior to aspirin alone and increases the risk of bleeding [7].

