Diagnosis of Heart Attack
When a person with chest pain comes to the hospital, the following steps are usually taken to make a correct diagnosis:
- Physical examination. First of all, the patient should tell the health care provider all the symptoms and what was happening before the symptoms appeared. This can provide the doctor with useful information to diagnose whether the pain is caused by the heart or is a non-heart problem.
- Electrocardiogram (ECG) is taken right after that, since it is the most useful method of diagnosing a heart attack. Not only can it be used to diagnose whether the patient has a heart attack or not, it can also be used to find out the location of the affected region, severity of the problem and it can even predict if the patient will have a heart attack in the near future.
- Blood tests. Blood tests are used to identify the levels of CK-MB (creatine kinase myocardial band) and troponins (troponin T and I), which rise when there is damage to the heart cells. Even though this test is very accurate, it is only useful if there is doubt as to whether the patient has a heart attack or not. In cases when there is a strong suspicion of a heart attack, the treatment will be administered before the results of this test can be acquired. Moreover, troponins are released only 2-4 hours after the heart attack (the time during which PCI or thrombolytic therapy should already have been performed). Another marker that has been used since 1954 is AST (aspartate transaminase); however, it became redundant and is no longer used after doctors started to use tests to identify cardiac troponins, which is a more reliable test.
- Echocardiogram is an ultrasound-based diagnostic imaging technique. It can provide the doctors with a wealth of information including location and extent of tissue damage, pumping capacity, etc. This method is usually used as a follow-up method for a patient who had a heart attack. This method also uses continuous wave Doppler ultrasound to accurately assess the blood flow within the heart.
- Radionuclide imaging. This technique involves the use of a radioactive tracer (thallium) that is injected intravenously in order to plot and detect its passage through the heart. This is a non-invasive test that can yield a lot of useful information. This technique can be used to determine:
o Whether a heart attack has occurred and its location
o The extent of muscle damage after a heart attack
o Severity of unstable angina
o Severity of chronic coronary artery disease
- Angiography is an invasive technique that involves using a narrow catheter inserted into an artery (usually of an arm or leg) and then passed all the way to the coronary arteries. A dye is then injected into the tube and an X-ray image is taken to create a map of the coronary circulation. This will reveal any blocked areas and the extent of the damage after a heart attack. This procedure can result in serious complications, although quite rare (less than 0.1%). These complications include kidney damage, heart attack or stoke. Moreover, allergic reaction can occur as a response to the dye being used. Another downside of this procedure is that it is very expensive.
Next Chapter: Treatment of Heart Attack