Coronary Artery Bypass Grafting (CABG)Here is an understanding of how blocked vessels of the heart are bypassed.
Coronary Artery Bypass or CABG
Coronary artery bypass grafting or “CABG” (often pronounced “cabbage”) is the most commonly performed “open heart” operation in the world. Cardiothoracic surgeons perform the procedure to bypass blocked blood vessels that supply good blood to the heart. The coronary arteries are the blood vessels that supply the heart with oxygen and nutrients. The blood through the body. The heart never rests like the other muscles in the body, and it demands a constant supply of fuel day and night. When coronary arteries are blocked the heart does not receive sufficient blood supply and therefore is deprived of oxygen and nutrients. The term ischemic heart disease (IHD) refers to this condition, when the heart does not get these fuels. When the heart is sufficiently ischemic (when the shortage of fuel is critical enough), the muscle begins to die. This is a “heart attack” or myocardial infarction (MI).
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How are blockages in the heart diagnosed?
When there are blockages of the arteries to the heart, an individual may experience chest pain or angina pectoris, or ultimately even a heart attack or myocardial infarction. In some cases, particularly in those with diabetes mellitus, heart attacks may be “silent.” A heart attack may be the first sign of coronary artery disease in many patients, and an electrocardiogram or EKG may be normal – even in the presence of coronary artery disease – if you have not yet had a heart attack.
You or your doctor may be suspicious of coronary artery disease if you have suggestive symptoms, multiple risk factors, and/or a strong family history of coronary artery disease. Risk factors include male sex, high blood cholesterol, diabetes mellitus, high blood pressure (hypertension), and cigarette smoking.
The presence of coronary artery disease is most often confirmed in two ways.
1. Noninvasive stress test – A stress test is performed on a treadmill with monitoring by electrocardiogram or echocardiography. It can be performed as an outpatient.
2. Cardiac catheterization or coronary angiography (CAG) is an invasive test in which a small tube or catheter is passed through the artery in the groin or arm to the heart, and contrast medium or “dye” is injected into the coronary arteries. X-ray pictures are taken which can show the obstructions present.
Once coronary artery disease is diagnosed, there are a number of treatment options including medicines, angioplasty, and surgery.
What are the indications for bypass heart surgery?
Evidence for CABG
Several studies in the past have shown a clear survival advantage for undergoing a coronary artery bypass. This benefit is particularly evident for patients who had disease of the left main coronary artery and those with disease of all three major coronary arteries and abnormal function of the main pumping chamber of the heart, the left ventricle. CABG may also be indicated in other specific circumstances, or when an individual patient is experiencing severe angina pectoris that cannot be controlled with medicines alone. The most important thing to keep in mind is that coronary artery disease is complex and every patient’s specific situation is different. You should therefore discuss your circumstances with your doctor.
Coronary artery bypass grafting (CABG) is performed for patients with coronary artery disease (CAD) to improve quality of life and reduce cardiac-related mortality.
Indications for CABG or Coronary Bypass
Class I indications for CABG from the American College of Cardiology (ACC) and the American Heart Association (AHA) are available on their website. This link will take you there for a detailed discussion. Briefly the below mentioned should suffice
Left main coronary artery stenosis >50%
3-vessel disease in patients with poor left ventricular (LV) function/asymptomatic patients or those with mild or stable angina
1- or 2-vessel disease in high-risk area in patients with stable angina
Other indications for CABG include the following:
Disabling angina (Class I)
Ongoing ischemia in the setting of a non–ST segment elevation MI that is unresponsive to medical therapy (Class I)
Poor left ventricular function but with viable, nonfunctioning myocardium
CABG may be performed as an emergency procedure in the context of an ST-segment elevation MI (STEMI) in cases where it has not been possible to perform percutaneous coronary intervention (PCI) or where PCI has failed and there is persistent pain and ischemia threatening a significant area of myocardium despite medical therapy.
CABG's performed yearly in India (approx)
CABG success rates
Stents Vs CABG. What does research show?
There is no one treatment guaranteed to be effective for all cases of coronary artery disease. But because there are different treatment options, it is important for every patient to have the information and resources necessary, after talking with a variety of healthcare professionals, to make informed decisions.
To determine the recommended form of treatment, physicians must first consider the extent of the problem. For those who have multivessel or left main coronary artery disease, surgery, not percutaneous intervention (PCI) or stents, offers the best long-range outcome, according to David Taggart, MD, Professor of Cardiovascular Surgery at England’s University of Oxford.
Dr. Taggart, who has criticized the increasing trend to treat all patients with PCI without offering a surgical option, showed flaws in 15 trials of angioplasty versus surgery. Dr. Taggert believes that for the studies, low risk patients were used, whose outcomes would be excellent with any treatment.
“For these studies, 176,250 people were screened to find the ideal patients, and 95 percent of those screened were excluded,” Taggart said. “None of the patients in the trial had left main disease. Patients do want less invasive treatment, assuming the results are the same. But that is definitely not the case here.”
Dr. Taggart believes that part of the problem involves those who are responsible for decision making with patients. He said that when patients are informed of possible heart problems, their research should extend beyond a visit to a cardiologist.
“Failure to discuss CABG (coronary artery bypass grafting) means that the patient is often denied the best treatment option,” Taggert said. “Consent for PCI is often obtained inappropriately. Doctors are obligated to explain alternate options if they are more effective. Usually, the cardiologist is the gatekeeper, and there is a conflict of self-interest there, it is a self-referral. All patients with multivessel disease should be treated by a multidisciplinary team, including a surgeon.”
Taggert said that CABG is a remarkably safe and effective procedure, and has a good, long range prognosis.
Studies have also shed light on the merits of CABG over PCI under appropriate conditions. For example, a study published 2005 in the New England Journal of Medicine concluded that for patients with two or more diseased coronary arteries, CABG is associated with higher adjusted rates of long-term survival than stenting. That study showed that patients with three blocked arties who received stents were 56 percent more likely to die within three years as those who had bypass surgery. That study was addressed in a Wall Street Journal article which said that stenting, the popular, minimally invasive angioplasty procedure, carries a higher risk of death long term than does open heart bypass surgery as a treatment for blocked arteries. The Journal reported that more than a third of patients who received stents needed either surgery or additional angioplasties with stents within three years.