Diagnosis of Coronary Artery Disease(CAD)
Diagnosis of CAD is based on your medical and family histories, your risk factors, a physical examination and a number of tests and procedures. If you are at a risk of CAD, a risk assessment for coronary artery disease, heart attack or stroke can be done by checking your blood pressure level and a blood test to determine the cholesterol level. Blood test to check for cholesterol level should be done in 10 to 12 hrs of fasting so that no food in your body that could affect the result.
The life style factors such as diet,exercise and whether you smoke or consume alcohol should be considered as part of the diagnosis. To confirm a suspected diagnosis, a number of different tests can be done which include:
An Electrocardiography is a must do test in suspected CAD. It should be done immediately when a suspected person is admitted to hospital. An ECG measures the electrical activity of your heart. It produces tiny electrical impulses, each time your heart beats. An ECG machine records these signals onto paper, to help determine how well your heart is functioning. whether the heart beat is steady or irregular.
The test takes around five minutes to perform. It is a painless procedure where electrodes are attached to your arms, legs and chest. Wires from the electrodes are connected to the ECG machine which records the electrical impulses.
An ECG helps confirm the diagnosis of a heart attack as well as helps determine what type of heart attack you have had. An ECG can show signs of heart damage due to CAD. Treatment will be carried out depending on the type of attack.
Holter monitoring may be recommended in some cases. In this type of ECG, you have to wear a portable monitor for 24 hours as you go about your normal activities. Certain abnormalities may indicate inadequate blood flow to your heart.
During stress testing, you are told to exercise to make your heart work hard and beat fast. If you are unable to exercise, you may be given medicines to increase your heart rate.
It needs more blood and oxygen, when your heart is working hard and beating fast. When the coronary arteries are narrowed due to formation of plaque, enough oxygen-rich blood can not be supplied to meet your heart's needs.
A stress test can show possible signs and symptoms of CAD, such as:
While you exercise and while you rest, images of your heart are taken as part of some stress tests. These imaging stress tests will show how well blood is flowing in your heart and how well your heart pumps blood when it beats.
An echocardiogram is a type of scan that uses sound waves to build up a moving picture of your heart. This will identify exactly which areas of the heart have been damaged and how this damage has affected your heart's function.
If diagnosis of a heart attack is uncertain and there are other possible causes of your symptoms, such as a pocket of air trapped between the layers of your lungs,a chest X-ray can be done. A chest X-ray can also done to check for the complications that have arisen from the heart attack, such as pulmonary oedema which is build-up of fluid inside your lungs.
A blood sample will be taken to test for heart proteins known as cardiac markers. These are the enzymes that help regulate chemical reactions that take place in your body. Damage to your heart from a heart attack causes these proteins to slowly leak into your blood.
The protein that has to be measure is known as cardiac troponin. Your troponin levels will be measured through a series of blood samples taken for few days. This will assess the amount of damage to your heart, and also help determine how well you are responding to treatment. Blood tests also check the levels of certain fats, cholesterol and sugar in your blood.
Coronary angiography is done to determine if a blockage or narrowing has occurred in the coronary arteries . This test also helps to locate the exact location of the blockage or narrowing.
In this test a thin tube known as a catheter is inserted into one of the blood vessels in your groin or arm. Using X-rays, the catheter is guided into your coronary arteries. A contrast agent is pumped through the catheter which will shows up on X-rays how it flows around and through your heart. This study can help locate the site of any blockage or narrowing.
This test does not detect coronary microvascular disease (MVD). This is because coronary MVD does not cause blockages in the large coronary arteries.
A computed tomography (CT) scan uses multiple X-ray images to create a cross-sectional image of your heart. Different types of CT scans are done to diagnose heart disease, such as a calcium score screening heart scan can be done to check for calcium deposits in your coronary arteries, or coronary CT angiography is conducted to check for fat or calcium deposits in your arteries.
Cardiac MRI uses radio waves, magnets, and a computer to create both still and moving images of your heart and major blood vessels as it beats.
Intravascular ultrasound (IVUS) is a imaging procedure where a specially designed catheter with a ultrasound probe attached to the end of the catheter is used. The proximal end of the catheter is attached to computerized ultrasound equipment. It allows the ultrasound technology to visualizing the inner wall of blood vessels.
IVUS is used in the coronary arteries to determine the amount of plaque built up at any particular point in the coronary artery. The accumulation of plaque within the artery wall over time can leads to heart attack and narrowing of the artery.
IVUS is useful to determine both plaque volume within the wall of the artery and/or the degree of narrowing of the artery lumen. It can be especially useful in situations in which angiographic imaging is unreliable. When angiographic images do not visualize lumen segments adequately, such as regions with multiple overlapping arterial segments, this test can be useful.
It is also used to assess the effects of treatments of narrowing of the artery such as with hydraulic angioplasty expansion of the artery, with or without stents, and the results of medical therapy over time.