Blood vessels supplying oxygenated blood to the body are called arteries. Atherosclerosis is a disease of arteries in which, a plaque (atherosclerotic lesion) builds up inside an artery. The plaque is made up of fat, cholesterol, calcium, certain types of blood cells and other substances found in blood. Over the course of time, plaque increases in size, hardens the wall of artery and narrows the artery from inside. This causes reduction in amount of blood that can flow through the artery. This disease can affect almost all major arteries of the body.

When significant atherosclerosis develops in arteries supplying the heart (coronary arteries) – it is called – Coronary Artery Disease (CAD). Development of significant CAD and subsequent reduction in amount of blood flowing through coronary arteries – either at rest or during periods of increased demand – can cause serious heart diseases like angina, heart attack, heart failure or even death.

Atherosclerosis causes coronary artery disease. Atherosclerosis in lesser amounts can be found in practically all adults. Only when atherosclerotic plaque becomes large enough to obstruct blood supply in an affected artery, it comes to medical attention. What causes atherosclerosis is not exactly known. However, there are well known risk factors that predisposes a person to atherosclerosis. We can classify risk factors in three – easy to understand – categories.

Risk factors over which you have no control – age, gender, family history of heart diseases.

Risk factors over which you have some control – diabetes, blood pressure, high cholesterol.

Risk factors over which you have absolute control – smoking, obesity, lack of physical activity, stressful life style, eating lot of junk and processed food.

There is a wide variation in symptoms a patient will experience – ranging from asymptomatic to sudden death. However, most of the patients with CAD will have some symptoms or complaints.

Chest pain or heaviness or constricting sensation in chest while doing some activity like walking or climbing stairs, sometimes pain is also felt in left arm or jaw or neck, pain usually gets relieved by rest.

Severe pain in front of chest, unrelated to any activity which doesn’t get relieved by routine treatment.

Feeling of persistent acidity, belching or gas after food, sometimes continuing for many hours and not relieved by routine home treatment of acidity.

Forceful feeling of one’s own heart beat in chest (called Palpitation), beats may be rapid or irregular.

Excessive perspiration, Excessive tiredness or fatigue.

Swelling of legs or face especially in morning and / or decreased urine output.

Feeling shortness of breath on some exertion or in severe cases even at rest.

Feeling of giddiness, light headedness or sometimes momentary loss of consciousness.

Patient may not have any symptoms of heart disease and CAD may be diagnosed solely on basis of tests done. Such tests may be done prior to other major surgery, during routine health checkup or during pre-employment checkup.

In some rare unfortunate cases this largely treatable disease presents as sudden death.

Please note none of these symptoms per se are diagnostic of CAD. The same symptoms can occur in other disease conditions also. If you have any of these symptoms, it is better to consult your doctor and get investigated properly.

Diagnosing coronary artery disease is an art as well as science.

An experienced doctor will inquire in detail about complaints / history of the patient, certain details of patient’s lifestyle, daily activities, habits, family history, other diseases etc. and conduct thorough physical examination. This interaction with patient gives the doctor crucial information about whether patient’s symptoms are attributable to CAD. If yes, what risk factors (like smoking, high blood pressure) and associated diseases (like diabetes, kidney problems) are present in that patient? By now the doctor has fairly accurate idea about what tests are needed either to prove or disprove diagnosis of coronary artery disease.

Many tests are available to diagnose coronary artery disease. For better understanding, we can classify them in three categories.

(1) Tests for identifying risk factors, other diseases and general health of patient.

Blood, Urine tests and chest x-ray can give information about general health of patient and can identify associated diseases or risk factors like diabetes, high cholesterol, damage to kidneys, lungs etc. In cases of acute chest pain blood tests (like Troponin or CPK-MB) can diagnose heart attack also.

(2) Tests to know effects of CAD on heart

Electrocardiogram (ECG)

It is a very useful test. It can diagnose problems with rate and rhythm of heart, any damage to heart by previous heart attacks and ongoing heart attack. A normal ECG does not rule out coronary artery disease and an abnormal ECG does not always mean coronary artery disease. So, doctors never rely solely on ECG to diagnose coronary artery disease, they always use other investigations to supplement / confirm the diagnosis.

Treadmill Test (TMT) 

In this test patient is asked to walk on a motorized, computer-controlled treadmill. The speed and slope (incline) of treadmill are increased as per fixed protocol, thus gradually increasing workload on heart and thus the heart rate. Throughout the test patient’s ECG is recorded continuously and blood pressure is measured periodically. Certain specific changes in ECG, fall of blood pressure, inability of patient to walk till a certain workload or heart rate or occurrence of chest pain or chest discomfort during the test are indicative of positive test and suggest insufficiency of blood supply to heart and indicate need for further testing.

Dobutamine Stress Echo (DSE)

Certain patients are unable to walk fast on treadmill (like those with knee arthritis), are bed bound or have certain pre-existing abnormalities in ECG. These patients cannot undergo routine TMT. In such patients stress test is done by artificially increasing the heart rate by giving a drug called dobutamine. Dobutamine is given in arm vein in calibrated and gradually increasing doses (like speed and slope of treadmill). Throughout the test echocardiography is done and movement of various areas / walls of heart is recorded. Areas of heart which have inadequate blood supply will move less compared to normally supplied areas. This finding suggests coronary artery disease and indicates need for further testing.

Echocardiography and Colour Doppler study (Echo + Doppler) 

This is the most basic and most extensively done test on heart in any major heart hospital. It is basically a sonography of heart. This study gives crucial information about structure of heart and its major blood vessels, size of its chambers, motion of all its walls, pumping of heart, all heart valves and disease within them if any, speed, pressure and direction of blood moving within heart, any fluid surrounding the heart, signs of heart failure etc. Certain specific abnormalities like reduced motion of a particular heart wall may suggest CAD and need for further tests.

(3) Tests to know extent and location of blockages in coronary arteries.

Coronary Angiography (CAG) 

This is a direct study, showing coronary artery itself. Currently it is gold standard in diagnosis of coronary artery disease. It is done in Catheterization Laboratory (Cath Lab). Cath Lab is basically a highly sophisticated, computer controlled, very expensive big X-ray machine. A special drug (radiological contrast medium or dye) is used to visualize the blood vessel. Main property of this dye is that it does not allow X-ray to pass, thus casting a shadow on image capturing device.

An artery in wrist or groin is punctured, a thin tube called catheter is passed up to the artery to be studied. The dye is then injected directly into opening of the artery and X-rays are taken in rapid succession as dye passes through the blood vessel, mixed with blood. Areas where blood passes, the dye also passes and is seen as a thick black line on image viewer. Where there are blocks in the artery, less blood and dye pass and it is seen as thinner line or area of narrowing.

This test shows in great detail the location, numbers and severity / percentage of blocks. If there is excess calcium deposition in an artery, it is also seen. Any major treatment decision like bypass surgery or angioplasty cannot be taken without doing this test first.

CT Coronary Angiography

This test also visualizes coronary arteries directly, but does not require an artery to be punctured. CT scan machine is also a highly sophisticated, computer controlled, very expensive big X-ray machine. In this test, dye is given in one of the arm veins instead of artery and scanning is done. The CT scanner gathers data form multiple x-ray images, processes them and gives coronary angiogram like images – showing distribution and severity of blocks. Though image quality is very good, usually conventional angiography is required before taking major treatment decisions for CAD.

Main role of CT coronary angiography is in ruling out the coronary artery disease and in follow up cases as and when needed after CABG or PTCA.

Coronary Artery Calcium Scoring

This test is also done in CT scanner machine, but dye is not injected. Only plain scans are done and amount and distribution of calcium deposited in major coronary artery is calculated. This test does not show blocks but predicts future possibility of coronary artery disease with some certainty. More calcium means higher chances of developing coronary artery disease in future.

Coronary artery disease treatment is best decided by quantifying the disease by angiography whenever possible. After angiography there are three common outcomes.

• Normal Angiogram or very minimal disease: Patient is advised healthy lifestyle and preventive care. Any risk factors (like smoking, diabetes or hypertension) present are aggressively controlled to prevent or delay further development of CAD.
• Moderate Disease: In such patients there are blockages in one or more coronary arteries but the blockages are not tight or severe enough (usually less than 60%) to require any form of major procedures like angioplasty or bypass surgery. Patient is encouraged to live healthy life style, medicines like blood thinners (aspirin) and cholesterol reducing drugs (statins) are prescribed to control coronary disease. Any risk factors like smoking, diabetes or hypertension are aggressively controlled to delay further progress of CAD. Patients are advised routine follow-up with his /her doctor to monitor the treatment.
• There are significant blockages in one or more coronary arteries. Further treatment decision is taken taking in to account – number of blockages, their location, their length, shape of coronary artery, amount of calcium present, presence of other diseases especially diabetes and general condition of patient. Angiography is reviewed by cardiologist and cardiac surgeon together, whenever necessary and most appropriate treatment option is suggested to the patient: Coronary Angioplasty (PTCA) or Bypass Surgery (CABG).

In certain patients, coronary angiography is not possible either due to patient reluctance, non-availability of Cath-Lab or patient being very high risk for the procedure of angiography. In such situations based on patient’s symptoms, associated risk factors, ECG and echocardiography findings, if there is high probability of CAD, appropriate treatment can be started even without angiography.

CABG means Coronary Artery Bypass Grafting. As the name suggests, the block is bypassed. A new channel or pathway or diversion is created for blood to flow, bypassing the block. The block itself is not removed. To create the new pathway for blood to flow, patient’s own blood vessels from other parts of body are taken and connected to diseased coronary artery beyond the block.

• Normal Angiogram or very minimal disease: Patient is advised healthy lifestyle and preventive care. Any risk factors (like smoking, diabetes or hypertension) present are aggressively controlled to prevent or delay further development of CAD.
• Moderate Disease: In such patients there are blockages in one or more coronary arteries but the blockages are not tight or severe enough (usually less than 60%) to require any form of major procedures like angioplasty or bypass surgery. Patient is encouraged to live healthy life style, medicines like blood thinners (aspirin) and cholesterol reducing drugs (statins) are prescribed to control coronary disease. Any risk factors like smoking, diabetes or hypertension are aggressively controlled to delay further progress of CAD. Patients are advised routine follow-up with his /her doctor to monitor the treatment.
• There are significant blockages in one or more coronary arteries. Further treatment decision is taken taking in to account – number of blockages, their location, their length, shape of coronary artery, amount of calcium present, presence of other diseases especially diabetes and general condition of patient. Angiography is reviewed by cardiologist and cardiac surgeon together, whenever necessary and most appropriate treatment option is suggested to the patient: Coronary Angioplasty (PTCA) or Bypass Surgery (CABG).

In certain patients, coronary angiography is not possible either due to patient reluctance, non-availability of Cath-Lab or patient being very high risk for the procedure of angiography. In such situations based on patient’s symptoms, associated risk factors, ECG and echocardiography findings, if there is high probability of CAD, appropriate treatment can be started even without angiography.

There are two methods of doing bypass surgery: Beating Heart Surgery and On-Pump Surgery

Beating Heart Surgery: In this method of surgery, heart is not stopped during surgery, it continues to beat and supply blood to itself and rest of the body. A device called Heart Stabilizer is used to perform this surgery. This device is attached by suction to heart on sides of coronary artery to be bypassed. The device reduces movement of heart in that area by almost 80-90%, thus allowing surgeon to operate on relatively motionless heart. One after another, all vessels are bypassed.

On-Pump Surgery: In this method of surgery, a system of artificial circulation called – Cardio Pulmonary Bypass is used. Patient’s blood is passed through this machine, where oxygen is added, carbon dioxide is removed and blood is pressurized and returned to patient. Thus, this machine temporarily works as artificial heart and lungs, allowing heart to be stopped and surgery to be performed.

There is no particular difference in outcome and long-term results of surgery with either method. It is largely a matter of choice and preference of surgeon. Majority of surgeons in India prefer Beating Heart surgery.

Bypass surgery being a very major surgery, patient is admitted to the hospital a day before. This familiarizes the patient with the ward doctors, nurses, hospital and the surroundings. It also reduces anxiety in patient and this in turn helps in post-operative period. After patient is admitted, routine pre-operative work-up is done, which includes blood tests, chest x-ray and echocardiography. Blood bank is asked to reserve blood for surgery. Administrative formalities like insurance approvals, deposits etc. are also completed. You will be asked to sign a few papers whereby you are allowing surgical team to operate upon you next day – this is called informed consent.

Your surgeon will surely visit you in your room and answer any queries that you may have. Surgeon will also spare time to talk to your close relatives to explain them about surgery – next day. The anesthesiologist will also visit you, asses you, give some important instructions and will explain also anesthesia procedure and what to expect after you wake up from anesthesia. Our physiotherapist will also visit you and will teach you exercises to be done after surgery, which will hasten your recovery and reduce pain.

In preparation for surgery hair is removed from parts where incision (surgical cut) will be placed. Those area of body are painted with antibacterial solution and a sterile cloth is wrapped over it. We will request you to remove all ornaments, loose dentures and sacred threads from the body. You will be asked not to take anything by mouth (nil by mouth) for at least eight hours before surgery. We will give you a sleeping pill, a night before to help you sleep better. On day of surgery, though you can eat or drink anything, you can brush your teeth, do gargles, wash your face, do your routine prayers as per your daily routine. Few of your close relatives will be allowed with you in the room. At a scheduled time, you will be shifted from ward to operation theater on stretcher or wheel chair.

When you arrive at operation theater, nursing staff will verify your name, hospital identity tag and surgery to be done – to make sure correct patient is going for correct surgery in correct theater. Once you are wheeled in the operation theater complex, you will be moved to your designated operation theater. Operation theaters are little unusual and cold places and can feel bit scary to some. However, the theater staff is very friendly, caring and comforting. They will be with you, chatting with you all the time, never leaving you alone even for a moment in this unknown place.

You will be asked to lie down on operation table and they will cover you with a blanket, if you are feeling cold. Then they will attach ECG cables, pulse oximeter probe (to measure oxygen saturation in blood) and BP cuff. These things do not hurt at all. The anesthesiologist will arrive and greet you, then he /she will numb skin of your forearm or back of hand and place a small vein cannula to give you medicines and fluids. A small cannula will also be placed in front of your forearm, near wrist to measure your blood pressure continuously during surgery and for collecting blood samples as and when needed.

After this initial preparation, procedure of giving anesthesia starts. The anesthetist will give you medicines that will induce sleep. Once this stage is passed, you will not feel anything. Everything this stage onwards is done after making you completely unconscious. When you wake up, surgery is over and you are in ICU.