Ischemia (inadequate blood supply) of the heart is the biggest killer amongst all diseases and the world is facing a pandemic type of situation at present. The developing countries are facing the brunt now and in an unforseen magnitude. Rapid westernisation is probably responsible for it in a large measure. The disease is now occurring in young age groups particularly in the South Asian countries due to a peculiar genetic predisposition, which has become manifest after abundant availability of food and adoption of sedentary life styles.
The heart is a muscular organ, and is essentially a pump for circulation of blood. It is situated on the upper surface of the diaphragm. Deoxygenated blood (blood from which the organs have used up the oxygen) enters the right side of the heart from the two great veins, the superior and inferior vena cavae, and exits from the pulmonary artery to the lungs to receive oxygen. Blood enters the left heart from the pulmonary vein and exits from the aorta to supply the entire body.
The pump requires energy for its functioning which is provided by oxygen and food supply to the heart by a pair of its own set of arteries, called the coronary arteries. These arteries are distributed throught out the cardiac (heart) muscle and have to be open to channelize the required energy substrates to the heart tissues. A diminished caliber of these vessels will deprive the cardiac muscle its requirement of blood supply for it to function properly. The lumen of coronary arteries can be diminished by depositon of fat like substances by a disease process of atherosclerosis.
There are two main coronary arteries that arise from the aorta and course on the surface of the heart. The right coronary artery, through its many branches and sub-branches supplies the right side and the lower side of heart. The left coronary artery divides into two main branches - the left circumflex and the anterior descending - soon after its origin from the aorta. The circumflex branch supplies the lateral and the back portion of the heart, while the anterior descending branch supplies the front part and tip of the heart.
1. The main vessels or their branches can be occluded gradually by disease process of atherosclerosis. It decreases the oxygen supply to the cardiac muscle and the patient may experience chest pain (angina pectoris). The pain is more during physical stress as that steps up the demand for oxygen by the heart.
2. Prolonged reduction of blood supply to the heart muscle can impair its pumping action permanently, which can result in breathlessness during physical effort and sweling of feet and other parts of the body. Heart failure is a condition in which the heart does not work adequately, i.e. it pumps with a strength that is insufficient to supply the tissues.
3. Clot formation on top of artheroma on the inner lining in the vessel can lead to sudden stoppage of blood supply to cardiac muscle which can get damaged irreversibly. This irreversible damage to the heart muscle is called myocardial infarction (heart attack).
4. During the period of decreased oxygen supply to the heart muscle (myocardial ischaemia) the electrical activity of the cardiac tissues can be disturbed resulting in irregular heart action (arrhythmia), or a heart rate that is too slow or too fast. It may also result in sudden ceasation of heart's pumping action and death.
It can vary in severity from being almost symptom-free to sudden death.
1. Sudden Death: Ischaemic Heart Disease can cause sudden serious disturbance in the rhythm of the heart and at may stop functioning instantaneously. In fact Ischaemic Heart Disease is the commonest cause of sudden death.
2. Myocardial Infarction: The patient feels excruciating pain in the central chest and it may radiate to the left arm, neck, upper back or upper abdomen. The pain is generally associated with sweating, apprehension or giddiness. The affected person may have feeling of impending doom. The pain can last for a few hours unless relieved with treatment. At times the pain may be only in the left arm, upper abdomen, neck or back only without any chest component. It is very important to get medical attention at the earliest as the initial period of the illness is critical and most deaths occur within the first hour. Diabetics and the old may develop an infarction without pain (silent infarction).
Some patients may develop complications and have symptoms due to that. Breathlessness can ensue from poor pumping by the heart. Blood pressure may drop and the patient can go into shock if the heart function is severely compromised. It is a very severe complication with dismal outcome most of the times. Palpitations and severe giddiness may be the result of disorderly heart rhythm. Suddenly a hole may develop between the two sides of heart with severe defficulty in respiration. Rarely heart may even rupture causing sudden death.
3. Angina pectoris: Angina is a chest pain that is located in the centre of chest, left arm, neck, upper abdomen or middle of the upper part of back. The pain is classically brought on by physical exertion and relieved with rest or use of nitrates. The pain typically lasts a few minutes and rapidly subsides. Sharp jab like sensations in the chest are generally not due to angina. Acid dyspepsia is another common cause of central chest pain.
Some patients, especially diabetics or old age persons may have angina without chest pain (silent angina). Others may describe the pain as sensation of heaviness, breathlessness or uncomfortable feeling in the chest or upper abdomen. Symptoms may worsen with time as the disease progresses.
If one has the least suspicion of ischaemic heart disease it is always better to seek medical help.
Resting Electrocardiogram (ECG) is taken to confirm the diagnosis. The electrocardiogram (ECG) is a graphical record of the electrical activity of the heart. It appears as a line with waves named the 'p', 'q', 'r', 's' and 't' waves. In disease the waves of the ECG develop abnormalities. The ECG can help diagnose myocardial infarction (and several other heart diseases) in most cases but some patients with acute myocardial infarction may have a normal initial ECG. If an infarction is suspected the affected person is kept under observation for atleast 24 hours and the ECG's are repeated to be certain. Patients with angina generally have a normal resting ECG. They may show abnromality only at the time of angina.
Stress ECG also popularly known as Tread Mill Test is more helpful for diagnosis of angina pectoris. It not only helps in making the diagnosis but also supplies information about severity of the illness and is a helpful guide in advising the extent of physical activity to the patient.
Radionuclide studies of the heart viz. Thallium scanning, MUGA scanning and SPECT are other useful investigations in diagnosis of ischaemic heart disease. The patient is given an intravenous dose of radioactive tracer. Areas that are diseased can be picked out easily on mapping the radioactivity over the heart.
Holter monitoring is done to record the 24 hour ECG while the person is mobile and carries out all physical activities. It records the number of ischemic episodes that the person suffers suring the day. It is especially useful in detecting silent angina.
Echocardiography is a technique in which sound waves evaluate the structure and function of the heart. Echocardiography displays the heart in real time as it goes about its business in the body. It is used to visualise the parts of heart damaged by an infarction. It tells the extent of damage and its severity. It is useful for evaluation of heart's pumping action.
Coronary angiography is carried out by injecting a contrast and taking X-rays of the heart. It is the gold standard by which all other investigations for diagnosis of ischaemic heart disease assessed. Coronary angiography is necessary before any surgery of angioplasty for treatment of ischaemic heart disease. It is an invasive test and requires hospitilization for a day or two. The test clearly shows the extent and site of obstruction within the coronary arteries.
It is also important to assess the risk factors that are responsible for development for atherosclerosis. Levels of fat and its components in the blood are estimated. Hign levels of cholesterol and triglycerides predispose to the development of atherosclerosis. Blood sugar is estimated to rule out any possibility of diabetes. Diabetes is another important risk factor.
Aim of the medical treatment is to:
Diet is determined by the weight of the patient - whether overweight or not, underlying diabetes if any and the amount of different fats in the blood.
An overweight patient is advised to restrict intake of calories so that he might shed some extra kilograms. Excessive weight not only elevates the levels of serum fats but also puts an extra burden on already compromised heart.
If diabetes is associated sugars have to be restricted in addition to fats. High sugar levels in blood promote the development of atherosclerosis. Ideal body weight is also a must for control of diabetes.
Generally speaking the diet should
have a proper mixture of saturated, monounsaturated and
polyunsaturated fats. Most of the nonvegetarian diets
tend to have extra saturated fats, while vegetarian diets
have polyunsaturated fats in them. Animal foods like
beef, mutton and pork are rich in saturated fats. Fish
and bird meats have monounsaturated and polyunsaturated
fats in addition to saturated fats. Milk also has
monounsaturated and saturated fats. Vegetable oils
(except coconut oil) have varying proportions of
polyunsaturated and monounsaturated fats. Fresh fruits
and vegetables must also be present in abundant amount.
If medical treatment is considered inadequate surgical intervention may be necessary. Coronary angiography is always performed before deciding about surgery. Coronay Artery Bypass Grafting is the name of classical surgery for ischaemic heart dissease. Veins or artreries harvested from some part of the patient's body is used to bypass the occluded portion of the coronary artery. This is a major surgical procedure and the heart has to be stopped and opened for it. An alternative to Coronay Artery Bypass Grafting (an open heart surgery) is Coronary Angioplasty - which dilates the narrowed coronary arteries with the help of balloons introduced into them via a catheter inserted through the groin of the patient. Stents can be placed at the site of obstruction after balloon angioplasty to keep the artery patent for a longer period. Gradually angioplasty is replacing the need for open heart surgery to a great extent.
The best treatment for Ischaemic Heart Disease is to prevent it. Certain hygeinic practices may be helpful:
Praveen Gupta, MBBS (AIIMS), MD (AIIMS), is the Director
of Delhi Hospital at Jind, Haryana. After an outstanding
undergraduate and postgraduate career he left the major
cities to serve the rural population in Haryana, and has
established a center of excellence in a place where
medical care is most needed.
Last revised: May 15, 2000