Diagnosis
 
 
A wide range of tests are available to diagnose the different forms and stages of heart disease. In general, a doctor will start by taking the patient’s medical history and conducting a physical examination. Depending on the findings, a series of non-invasive and/or invasive tests may then be used to pinpoint the specific nature and severity of the heart condition which the patient is suffering from.
 
Non-invasive tests:
 
Chest X-ray
A conventional X-ray of the chest yields basic information about the size and shape of the patient’s heart, blood vessels, and lungs.
 
Electrocardiography / Electrocardiogram
Electrocardiography is a method of measuring the electrical impulses in the heart. This is usually done by placing 12 electrodes on the patient’s chest and limbs. The electrodes are then connected to a machine which records the rhythm, frequency of beats, and electrical conduction of the patient’s heart. The test takes about 10 minutes to complete, and the printed result is known as an electrocardiogram, or “ECG” for short.
 
It contains information about:

- the patient’s heart rhythm and heart rate
- any previous or on-going heart attacks
- the thickening of the heart muscle and enlargement of the chambers of the heart, if any;
- whether or not blood supply to the patient’s heart is poor.
 
Together, such data provides clues to the likely reasons for the patient’s cardiac condition as well as the appropriate course of treatment.
 
Holter monitoring
A variation on conventional electrocardiography is Holter monitoring. This is ECG monitoring done over time, usually in the course of a normal day’s activities. For this form of electrocardiography, the patient carries an ECG monitor in a small satchel worn on his body so that measurements may be taken of any spontaneous periods of chest pains and/or irregular heart rhythms which he may experience during the test period.
 
Exercise Stress Test
Sometimes, an ECG is done while the patient is exercising. Typically, the patient is asked to run on a treadmill while wearing the usual ECG electrodes. Recordings are taken simultaneously at 3-minute intervals, with the speed and elevation of the treadmill being gradually increased in the course of the test until the patient either reaches his target exercise heart rate or develops chest pains and indicates that he is unable to continue with the test. An exercise ECG is most helpful for a patient who experiences chest pains only upon physical exertion, but who otherwise has normal ECG results when at rest. It allows doctors to assess the amount of physical activity which such a patient can undertake comfortably (also known as his “exercise tolerance”). It also sheds light on how well his heart responds to the stress arising naturally from exercise.
 
Echocardiography
Echocardiography is a technique which uses sound waves (ultrasound) to evaluate the internal structure, movement, chambers, and valves of the patient’s heart. It is also useful in the diagnosis of heart attacks and coronary heart disease. Spectral Doppler echocardiography is a special form of echocardiography which analyses the speed and direction of blood flow in the patient’s cardiovascular system. It helps to highlight any disorders of the heart valves, coronary muscles, and coronary arteries which the patient might have.
 
Computed Tomography (CT) scan
Also known as a CAT scan, a CT scan provides cross-sectional images of the patient’s chest, including his heart and the surrounding blood vessels. It is useful in the diagnosis of cardiac tumours, aortic disease, as well as pericardial disease (disease of the pericardium).
 
Magnetic Resonance Imaging (MRI)
In MRI, powerful magnets are used to produce three-dimensional, high-resolution images of the patient’s internal body structures. Such images, which include detailed information about the heart muscle, are vital in the detection of damage caused by a heart attack, diseases of the coronary arteries, and other cardiovascular defects.
 
Invasive tests:
 
Nuclear Imaging
These tests involve injecting radioactive substances known as radionuclides (for instance, thallium) into the patient’s bloodstream. As the radioactive substances flow through the patient’s cardiovascular system, scans and computer-generated images are taken to detect how well the heart’s chambers are working, how good blood supply to the heart is, and whether or not any heart muscle has been damaged by a heart attack.
 
Nuclear imaging may be combined with an exercise stress test to augment the accuracy of the results obtained. In such cases, the radioactive substances injected into the patient are mapped both at the peak of exercise and at rest so as to identify areas where the coronary arteries are narrowed, as well as the extent and severity of the patient’s blood flow abnormalities.
 
Cardiac Catheterisation / Coronary Angiography
Cardiac catheterisation is commonly performed before invasive procedures such as “balloon” angioplasty in order to determine the type and extent of surgery required. A catheter in the form of a thin plastic tube is inserted into an artery or vein in one of the patient’s limbs and directed into the chambers of his heart and the coronary arteries. Once the catheter is in position, the blood pressure, oxygen content of the blood, and pumping ability of the heart can be assessed.
 
The catheter may also be used to inject a dye into the coronary arteries. As the dye flows through these arteries, X-rays are taken (coronary angiography). The dye shows up as white lines on the X-rays, with disruption or narrowing of the lines indicating areas where the coronary arteries are obstructed.
 
Trans-Oesophageal Echocardiography
Unlike conventional echocardiography which is non-invasive, in trans-oesophageal echocardiography, a special instrument is inserted into the patient’s throat and passed down his oesophagus (the tube connecting the mouth to the stomach). As part of the oesophagus lies close to the heart, the images captured by the instrument are able to give a very clear picture of the heart’s structure.
 
Blood tests
Certain substances such as creatinine kinase and troponin are released into the bloodstream when the heart is damaged during a heart attack. Their concentrations peak after a specific period of time from the initial moment of heart attack. Blood tests to detect the presence of these substances are useful in helping doctors to estimate the time of, or to confirm the occurrence of a heart attack. They also help in the detection of any injury which may have been caused to heart muscle due to a heart attack.
 
Classification Of Heart Disease
Based on the results of the diagnostic tests performed, doctors usually classify a patient’s heart condition based on how severe his symptoms are. The most commonly used classification system in this respect is the New York Heart Association’s Functional Classification, which places patients into one of four categories depending on the extent to which their cardiac problems limit their capacity for physical activity.
 
Class Nature of Symptoms
I No symptoms and no limitations on ordinary physical activities
II Mild symptoms, with slight limitations on ordinary activities. Patient is comfortable at rest.
III Symptoms are sufficiently serious to place marked constraints on ordinary physical activities as well as on less strenuous activities. Patient is comfortable only at rest.
IV Symptoms impose severe limitations on patient’s daily activities. Patient experiences symptoms even while at rest.