|What Tests Are Used To Diagnose A Heart Attack?
On Route To Hospital
Most tests are carried out in hospital but some can be started by emergency medical personal while you are in the ambulance. Medics will take your vital signs, check for heart attack symptoms and assess your overall condition and determine if medical care is immediately needed or can wait until you arrive in hospital. They may take an electrocardiogram test (ECG), a graphic record of the electrical activity of the heart and relay this to the emergency department before you arrive. They also carry a variety of drugs and equipment including oxygen, heart medications (including nitrate medications), pain relievers like morphine and an automated external defibrillator (AED - image) to restart your heart should you experience sudden cardiac arrest.
All patients arriving at emergency with signs of chest pain or heart attack will undergo several tests to determine the cause. Diagnosing if a heart attack has occurred is extremely important because the sooner it is diagnosed, the sooner it can be treated and the greater the chance of surviving without disability. Medical staff will use a stethoscope to listen to your heart and lungs and ask you a battery of questions about your heart attack risk factors and family medical history of heart disease. If not already carried out in the ambulance, an ECG will be the first test to diagnose a heart attack and certain blood tests will also be completed.
Image. This test records the electrical activity of the heart via electrodes attached to your skin. It is non-invasive and painless. As damaged heart muscle does not conduct electrical impulses normally, an ECG may show that a heart attack has occurred or is in progress. ECG results tend to be less accurate in women than in men. Women are more prone to inconclusive results - that is, results which do not give a clear yes or no answer. Scientists are not sure why this is, but results can be affected by the phase of a menstrual cycle or contraceptive use, indicating that the female sex hormones are a factor. If results are inconclusive the patient may be sent for an exercise stress test or nuclear heart scan.
A heart attack causes certain enzymes to slowly leak into your blood stream, and emergency room doctors will take a sample of your blood to check for these enzymes. These blood tests are referred to as CK (creatine kinase), CKMB, Troponins and C-reactive protein test.
If a heart attack is diagnosed or one is occurring, doctors will take immediate steps to treat you (see heart attack treatment for more information). Other additional tests may also be carried out, including:
This allows doctors to check the size of your heart and the blood vessels (coronary arteries) supplying it. It also allows them to check for signs of fluid collection on the lungs.
Image. This test uses ultrasound technology (similar to a pregnancy ultrasound scan) to produce an image of your heart. A transducer device is held against your chest and sound waves are bounced off your heart and reflected back to a monitor as images. It can help identify where the heart has been damaged and if it is not pumping blood normally. If you are obese or have large breasts the images may be a little hazy making it difficult to interpret. This test does not involve radiation, so it is safe for pregnant women.
Nuclear Stress Test
Also called a nuclear heart scan (image) and radionuclide myocardial perfusion imaging. During this test a radioactive dye is injected into the bloodstream and then traced with an external camera as it progresses towards the heart. It can highlight any blockages in the blood vessels, damage to the heart muscle and function. A few studies indicate that women who test positive have a higher risk of dying from a heart attack than men who test positive.
Heart catheterization is an invasive procedure which involves inserting a long thin flexible tube (catheter or cath) through an artery in the arm or groin and is then directed towards the coronary arteries. It can be used to detect blood pressure, blood flow and collect samples of blood from the heart.
This procedure (image) is often performed along with a heart catheterization. With coronary angiography, a dye is injected through the cath and tracked using an external x-ray machine. This test may be performed during an emergency to check for blockages related to a heart attack or carried out electively (non-emergency) to check for symptoms of coronary heart disease. If a blockage is found, the surgeon may immediately perform coronary angioplasty (a treatment to unblock the arteries - image).
Follow Up Tests
After you go home from hospital, your doctor may order some follow up tests including an exercise stress test (image). This test is used so that doctors can determine the best long-term treatment for patients. It involves tracking the activity of the heart (using an ECG) while the person is at rest and while stressed (on a treadmill or exercise bike). Alternatively a nuclear heart scan may be offered.
Should I Have a CT Scan To Screen For A Heart Attack?
This is currently a big question in medicine today. Although a CT scan (technically called a 64-slice computed tomography) can achieve attractive pictures, the test still involves a considerable amount of radiation to see whether there are any blockages in the coronary arteries. Thus, these tests are not recommended for general health screening but are only carried out after some other initial screening is done. Other heart disease testing methods may be just as effective (and less expensive).
Chest Pain At Rest But Negative Blood Tests
If a woman arrives in hospital with chest pain at rest (considered unstable angina), but her blood tests indicate a heart attack has not occurred, new guidelines by the American Heart Association say that medical treatment and a stress test is the correct procedure. If the stress test is positive, many women will then go on to have cardiac catheterization.