What are the tests your doctor will do to detect heart disease? What to expect from the tests?
If you visit the cardiologist or heart doctor with the symptoms of angina, your doctor will listen to your description about the pain or discomfort. To see if you are at threat of getting coronary heart disease, your doctor will ask you some questions related to your lifestyle, profession & your exercise habits. Your cardiologist will check your heart rate, rhythm, blood pressure & assess your general condition. Then your heart doctor will do an ECG, 2D echocardiography, few blood investigations, scans or coronary angiography depending upon your heart condition. Some of the tests required for a heart patient are described below.
1. Electrocardiogram (ECG/EKG):
Each beat of your heart is triggered by an electrical impulse generated from special cells in the heart muscle. An electrocardiogram records these electrical signals as they travel through your heart. It is used to diagnose abnormalities of the heart including arrhythmia (electrical disturbances of the heart) or to show ischemia (lack of oxygen & blood) to the heart. It can detect a ST elevation heart attack, but it cannot detect unstable angina or non ST elevation heart attack.
An ECG is done on an outpatient basis. Your doctor will apply electrodes and gel to your hands, feet and chest. These electrodes measure the electrical activity of the heart. This electrical activity of the heart is recorded on a thermal paper with squares. It is advisable to keep a photocopy of the thermal recording as it fades away over a period of time
2. Echocardiogram (2D or 3D):
An echocardiogram uses an ultrasound transducer that produces high frequency waves to produce detailed pictures. 2D or 3D echoes allow your doctor to examine the functioning of heart valves & motion of the walls of the heart. Your doctor can analyze these images to identify heart problems. Echocardiogram is used to assess the pumping function of the heart (ejection fraction or EF). The normal EF is 55-65%. Reduced movement of a part of the heart muscle can be because of a block in major arteries of the heart. There may be choking or leakage of any of the four heart valves. This is also visible on 2D echocardiography. Your doctor will also measure pressures in different chambers of the heart.
An echocardiogram is done on an outpatient basis. Your cardiologist will be able to see live images and videos of your heart on an ultrasonography machine. An echocardiogram takes 15-30 minutes. The echocardiogram can be repeated as often while in the hospital and on serial follow ups on an outpatient basis.
3. Stress Test:
The heart blood vessels may be having a block. Despite the block, the blood supply may be sufficient for heart muscles at rest. However, during exercise the blood and oxygen requirement increases. We can assess the increased oxygen requirement and the possibility of an underlying block by doing a stress test. During a stress test you exercise by walking on a treadmill or pedaling a stationary bicycle. While exercising your heart doctor will monitor your ECG, blood pressure and functional capacity of the heart. Any variations in the parameters suggest heart disease or reduced blood supply to the heart muscles.
4.Myocardial perfusion scan:
Myocardial perfusion scan or radionuclide scan helps measure blood flow to your heart muscle at rest & during stress. It is similar to a routine stress test but during a nuclear stress test, (isotope) a radioactive substance is injected into your bloodstream. Then a large camera is put in a position close to your chest which takes pictures of your heart. These pictures help your doctor to evaluate how much angina has affected your heart, & what treatment should be continued. It also helps to figure out what parts of the heart muscle are dead or alive. This helps the doctor to plan for coronary angioplasty.
5.Chest X-ray :
Chest X ray takes images of your heart & lungs. This is to look for other conditions that might explain your symptoms & to see if you have an enlarged heart, pneumonia or other lung conditions.
6.Blood Tests :
Samples of your blood can be tested for the presence of troponin enzymes. Troponins slowly leak out into your blood if your heart has been damaged by a heart attack or severe angina. Troponins start being detected in your blood stream as early as 4-6 hours after a heart attack and may be detectable up to 7-10 days. Elevated Troponins is an indication of a recent heart attack. Normal Troponins does not rule out a heart attack. NT-pro BNP is a test to rule out heart failure. Heart failure is a condition which indicates that there is increased pressure in the heart. A lipid profile measures the total cholesterol, LDL (bad cholesterol), HDL (good cholesterol), triglycerides and lipoprotein A levels. The lipid profile levels are targeted at different levels for different patients, according to the risk factors.
A basic complete blood count, renal function test, electrolytes, liver function test, thyroid profile, vitamin levels may be prescribed by your doctor if necessary.
7.Coronary Angiography :
Coronary angiography is a gold standard to detect blocks in the heart. Coronary Angiography uses X-ray imaging to examine the inside of your heart's blood vessels (i.e. left anterior descending, left circumflex and right coronary artery). The angiography is performed to detect the perfect location & number of blocks in the coronary arteries.
Coronary angiography is done as a daycare procedure in the cardiac catheterization laboratory. It is a safe procedure. The patient remains conscious throughout the procedure and can talk to the doctor. The patient is given a local anesthetic (in the forearm or groin) and a thin tube is used to inject dye into the arteries of the heart. These arteries are studied under X ray (C arm). Live movement of blood can be seen in the arteries of the heart and blockages if any can be detected. Based on the number, type, site of blockages your doctor will advise you medicines, angioplasty or bypass surgery.
8.Cardiac Computerized Tomography (CT) Angiography Scan:
The CT coronary angiography is used to detect anatomy of the heart and calcium in the arteries of the heart. The CT should not be used as a routine screening test for coronary artery disease. If the CT angiography has a low calcium score and does not show blockages, patient can be treated medically. However, if the CT angiography shows blockages, these must be confirmed by a conventional coronary angiography.
In this test, contrast dye material is injected through a small line in the arm vein. An X-ray tube inside the machine rotates around your body & collects images of your heart & chest. The images thus collected are used to analyze if there are any blockages in the heart arteries.
9.Cardiac MRI :
A cardiac MRI gives detailed information about the function of the heart muscles (i.e. Viability - living, scarred or dead heart muscles). It also helps to study the function of heart valves and blood flow inside the chambers of the heart. The cardiac MRI may be done to plan for angioplasty or bypass surgery. This information is then correlated with a coronary angiography.
A cardiac MRI is done as an OPD procedure. The patient is put in a tube like machine. The structure and function of the heart is studied over 45-60 minutes after injecting a dye. It is relatively safe; however some people may feel claustrophobic inside the MRI machine. Be cautious not to have any metal objects on your body or in your clothes during the MRI test.