By Dr Ananya Mandal, MD
Cardiovascular diseases are diagnosed using an array of laboratory tests and imaging studies. The primary part of diagnosis is medical and family histories of the patient, risk factors, physical examination and coordination of these findings with the results from tests and procedures.
Some of the common tests used to diagnose cardiovascular diseases include:
Laboratory tests are used to detect the risk factors for heart diseases. These include detection of the fats, cholesterol and lipid components of blood including LDL, HDL, Triglycerides.
Blood sugar and Glycosylated hemoglobin is measured for detection of diabetes. C-reactive protein (CRP) and other protein markers like Apolipoprotein A1 and B are used to detect inflammation that may lead to heart diseases.
During a heart attack, heart muscle cells die and release proteins into the bloodstream. Blood tests can measure the amount of these proteins in the bloodstream. High levels of these proteins are a sign of a recent heart attack.
One of the markers of heart attack is the Cardiac Troponin-T. Other biomarkers include fibrinogen and PAI-1, high levels of homocysteine, elevated asymmetric dimethylarginine and elevated brain natriuretic peptide (also known as B-type) (BNP)
This is a simple and a painless test that records the heart’s electrical activity. The patient is strapped to the instrument with several patches or leads placed over his or her chest, wrists and ankles. A small portable machine records the activities of the heart on a strip of graph paper.
The test shows how fast the heart is beating and its rhythm. The strength and timing of the electrical signals as they pass through the heart are also seen. An EKG/ECG can help detect a heart attack, attacks of angina, arrhythmias etc.
For this test, the patient is made to work hard e.g. run on a treadmill or exercise while the leads of EKG/ECG are placed over their body. Those who cannot exercise are given pills to raise their heart rate. The test detects the effects of the exercise on the heart.
In patients with atheroisclerosis and coronary heart diseases the arteries that are narrowed by plaques cannot supply adequate blood to the heart muscles while it is beating faster. This may lead to shortness of breath and chest pain. The EKG/ECG pattern, arrhythmias etc. also show the possibility of a coronary artery disease.
This test uses sound waves to create a moving picture of the heart. This is also a painless test where a probe is rolled over the chest and the machine creates the image of the heart on the monitor. This provides information on the shape, size, workings, valves and chambers of the heart.
Echocardiography may also be combined with Doppler to show the areas of poor blood supply to the heart. It shows the areas of the heart muscle that are not contracting normally, and previous injury to the heart muscle.
Coronary Angiography and Cardiac Catheterization
This test is an invasive test. A dye is injected into the veins to reach the coronary arteries. This is done via coronary catheterization. Thereafter detailed pictures of the blood vessels of the heart are taken using special imaging methods. This is called coronary angiography.
Cardiac catheterization involves threading of a thin, flexible tube called a catheter via a blood vessels in the arm, groin (upper thigh), or neck. The tube is inserted under imagin guidance till it reaches the heart. Coronary angiography detects blockages in the large coronary arteries.
Chest X Ray
This is a test that shows the shape and size of the heart lungs and major blood vessels. This is a test seldom used in diagnosis of heart diseases as it does not provide added information over echocardiography and other imaging studies.
Electron-Beam Computed Tomography or EBCT
EBCT helps to detect the calcium deposits or calcifications in the walls of the coronary arteries. These are early markers of atherosclerosis and coronary heart disease. This is not a routine test in coronary heart disease.
Cardiac MRI (magnetic resonance imaging) that uses radio waves, magnets, and a computer to create pictures of the heart. This gives a 3D image of the moving as well as still pictures of the heart.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)