There are three major coronary arteries. The right coronary artery (RCA), the left main coronary artery which branches into the left anterior descending (LAD) and the left circumflex (LCx). Each of these 3 arteries further branch out into a extensive network to supply blood to the heart.
These arteries can become diseased when cholesterol, a fatty substance, carried in the blood gets deposited and builds up to form a plaque which obstructs the artery. This results in reduction of blood flow in the artery proportional to the degree of obstruction. This reduction results in angina (pain, discomfort or pressure in the chest). When the obstruction becomes total usually due to a blood clot forming over a plaque the blood flow is completely cut off resulting in a myocardial infarction or heart attack. The attack can be mild or severe depending on the degree of vascular bed affected which in turn depends on the site of obstruction. Higher the site of obstruction -severe the degree of attack. For example a total obstruction to the left main can result in sudden death.

• Gender (Males and Females)
  
• Age
  
• Smoking
  
• High Blood Pressure
  
• High Cholesterol and lipids
  
• Diabetes
  
• Excessive Alcohol
  
• Over weight (Obesity)
  
• Lack of exercise
  
• Family history

Diagnosis of CAD :

Diagnosis of CAD is based on history, thorough physical exam and specific diagnostic tests. These include

Chest X-ray	:	Provides information about heart size and status of lungs.
ECG	:	May be normal except in an acute attack where it is diagnostic. It may also show evidence of old infarct.
Cardiac enzymes	:	The 3 main cardiac enzymes are creatinine phosphokinase -MB (CPK- MB), Troponin -T and Troponin -I. The levels of these naturally occurring enzymes are increased in the event of a heart attack. Larger the attack greater the level of increase. Useful only in acute situation.
Treadmill test (TMT)	:	This is the most common screening test for CAD. This monitors the ECG during exercise based on a standard protocol for age. Results are given as positive or negative. For details visit Cardiology.
Echocardiogram	:	Echo is useful in all situations. It detects abnormalities in the wall motion of the heart indicating affected areas. It is also very useful to assess the heart (LV) function which is a very important far prognostic indicator. Learn more about the role of Echo -visit Cardiology.
Nuclear Scan	:	Nuclear Cardiology is useful in 2 situation of CAD To assess LV function As a screening test for CAD. A radioactive tracer specific for heart is injected and the camera scans the heart. Areas that are deprived of blood supply can be detected. Learn more about Nuclear Cardiology visit Nuclear Medicine.
Coronary Angiography	:	This test is the 'gold standard' for the diagnosis of CAD. It also provides the information needed for deciding on the treatment option. This test is mandatory before surgery. Coronary angiogram showing near total block of RCA Learn more about coronary angiography and angioplasty - visit Cardiology.

 Coronary Artery Bypass Surgery (CABG) :

          CABG creates new pathways around the areas of blocked arteries restoring blood flow to heart muscle. These pathways are created using blood vessels, an artery or vein taken from another part of the body. These blood vessels are called conduits. The commonly used conduits are:-

Internal Mammary Artery      (IMA)	:	This is located inside the chest wall on either side. The one on the left side, left Internal Mammary Artery or LIMA, is the most important conduit. It is a live conduit (still connected to main artery) and is used to bypass the most important coronary artery, LAD. This conduit has the best long term patency and is said to be immune to Cholesterol deposition. The right IMA (RIMA) is also used either as live graft or free graft. Use of both IMA (BIMA) has shown to have better long term results. BIMA is done in younger patients with good coronary arteries (targets). BIMA is avoided in diabetics as it can retard sternal healing. LIMA anastamosed to LAD
Radial Arteries	:	This is the artery used by every Physician to check pulse. It is a very good conduit and we use it routinely. It is usually taken out from the non dominant hand, commonly the left. Adequacy of circulation to the hand is assessed by a simple test caned the Allen's test before surgery to determine the suitability of taking out this artery. This conduit is commonly used to graft the left circumflex system (LCx) .
Saphenous Vern	:	This was the conduit used when CABG started and is still used widely. They are excellent conduits and are the one used in an emergency situation. Major disadvantage is the poor long term patency rate.

 Comparison of Patency Rates of Common Conduits :

How is Bypass performed : The chest is opened in the midline by sawing through the sternum (breast bone). Conduits required are harvested. The heart is exposed. There are two ways of performing the bypasses (l) By placing the patient on the heart lung machine and stopping the heart (Conventional technique) (2) On a beating heart called the "Off Pump" or OPCAB technique.

tly the trend is towards OPCAB. In our centre we perform 60% of our CABG's by this technique. The major difference is the avoidance of heart lung machine. The heart is a dynamic organ with blood flowing continuously. It is very difficult to perform a bypass on a beating heart. It is indeed technically demanding. But newer technology which is continuing to rapidly evolve in this area is making it possible, simple and safe.

The device used are called 'Stabilising Systems'. The commonly used one is the 'Octopus System'. They immobilise a small area of the heart at the site where the bypass is to be performed. The bleeding problem is circumvented by the usage of small hollow tubes called shunts which are placed in the artery after opening. The bypass is then constructed in the usual way. The major advantages are the absence of any side effects due to the usage of heart lung machine, lesser hospital stay, quicker recovery and less need for blood transfusion.

The procedure has its own limitations. It cannot be used in all patients due to various reasons. Our surgeons will discuss with each patient about the feasibility of doing CABG by this technique.

Octopus stablising system

Guidant composite stabilising system

Risks of CABG :

          The standard risk for the procedure in our centre is 2% comparable to the best in the world. Risk increases with age, female sex, diabetes, previous strokes, poor LV function, diffuse coronary disease and depressed kidney function (Creatinine > 2.0).

          Our surgeons will discuss the risk involved for each patient based on his condition at the time of consultation.


 After CABG :

          CABG is not a curative surgery. It improves symptoms and quality of life by restoring blood flow. Long term benefits depends on a good post surgical program. Every patient after CABG should follow ABCDEF rule :-

• Aspirin and or/Clopidogrel, ACE inhibitors, Avoid excess alcohol.
  
• Beta Blocker.
  
• Cholesterol control (<100 mg/dl) - Statin therapy.
  
• Diabetes control (fasting < 90 mg/dl), Diet.
  
• Exercise (Preferable to enroll in a "Cardiac Rehabilitation Program" )
  
• Follow up
  
  Check with your Cardiologist on the above.