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Heart Attack – What Causes It?

There are two main causes of clogged coronary arteries:

  • Coronary Artery Disease: also referred to as atherosclerosis, is a gradual process in which fatty layers (plaque) build up on the inside of the arterial walls. As the plaque builds up and the artery narrows, there is less room for blood flow.
  • Coronary Thrombosis: is a blood clot that lodges inside a coronary artery and prevents the flow of blood.

Angina vs. Heart Attack

Angina (chest pain) is not a heart attack, but may warn you of an impending heart attack. Angina also occurs when the heart muscle is not receiving enough oxygen. With angina, however, no permanent damage is done to the heart muscle.

  • Angina is most commonly experienced with an activity such as shoveling snow, walking upstairs or uphill, consuming a large meal, or a stressful event.
  • The symptoms of angina are similar to those of a heart attack. They are most commonly described as a squeezing, burning, tightness, fullness, or pressure across the chest. This feeling may spread to the shoulder, arms (especially the left), neck, jaw, teeth, earlobes, as well as the upper back between the shoulder blades. Numbness or tingling in the arms or hands may occur.
  • Angina can be mistaken for indigestion.
  • Unlike a heart attack, angina may be relieved by rest and/or nitroglycerin within 15 minutes.

How is a Heart Attack Diagnosed?

Your physician has several tests at his/her disposal when determining whether or not you have had a heart attack.

Medical History and Physician Exam

Your physician will need your medical history and to perform a complete physical examination. There will be questions asked regarding your present state of health, including specific symptoms you are experiencing. Questions concerning your lifestyle also need to be answered, i.e. dietary habits, exercise routine, stress, smoking history, alcohol consumption, and medications. It is important for your physician to know your family’s medical history as well.

12 Lead Electrocardiogram (EKG)

An electrocardiogram records the electrical activity of your heart. A series of EKGs are taken during your hospitalization to observe the gradual changes which are indicative of a heart attack.

Blood Tests

Cardiac enzymes are normally stored in the cells of the heart muscle. When the heart is injured, cardiac enzymes are released into the blood stream. A series of blood tests are drawn in order to observe changes of each specific enzyme.

Test & Procedures

Thromblytic Therapy

In thrombolytic therapy, medication is given intravenously to dissolve the blood clot causing the heart attack. Once the blood clot is dissolved, blood flow can be restored to the affected area of the heart. Activase (t-PA) or Streptokinase are the most common medications used for dissolving a blood clot.

Cardiac Catheterization (coronary angiography)

A cardiac catheterization is an invasive procedure performed in a special lab under a local anesthetic and sterile conditions. A catheter is introduced into the heart via an artery and/or vein located in the groin or arm. Dye is injected through the catheter into the coronary arteries and/or heart’s chambers, while an x-ray is taken and recorded on film. This procedure allows the physician to visualize the coronary arteries, as well as the function of the heart and its valves.


An echocardiogram is a non-invasive procedure using ultrasound waves to visualize the structures of the heart on the screen with the use of a probe. The hand-held probe is moved across the chest to visualize the movements of the heart’s valves and chambers.

Transesophageal Echocardiogram

A transesophageal echocardiogram is the same as a standard echocardiogram, except a miniaturized transducer (the probe) is passed down the esophagus by means of a flexible scope to visualize the heart.

Graded Exercise Stress Test

A graded exercise stress test involves exercising on a treadmill or bike at increased degrees of difficulty while the heart’s response is recorded on an electrocardiogram (EKG). The level of exercise tolerance is measured by changes on the EKG, reported symptoms, as well as blood pressure and heart rate response. It also allows the physician to assess the effectiveness of your medical treatment. Patients recovering from a heart attack are usually given a low level exercise stress test prior to discharge.

Thallium Stress Test

A thallium stress test may be done at rest, or follow the same procedure as a graded exercise test, with an intravenous injection of a low dose of radioactive material at peak exercise. This is immediately followed by a scan of the heart to visualize areas of the heart that do not receive sufficient blood supply. A comparative scan will be done four hours later to note any changes at rest.


A MUGA scan uses low dose radioactive material given intravenously to visualize the heart’s pumping action (ejection fraction).

Persantine Stress Test

A persantine stress test is similar to the graded exercise stress test except that a medication called persantine is used to elevate the heart rate instead of exercise.

Stress Echocardiogram

A stress echocardiogram is similar to a graded exercise stress test, except that an echocardiogram is performed prior to the stress test and immediately following the stress test. A stress echocardiogram allows the physician to visualize changes in the pumping action of the heart between rest and exercise.

24-Hour Holter Monitor

With a 24 hour Holter monitor, electrodes are placed on the chest wall and connected to a small tape recorder which records the heart rhythm for a 24 hour period. The patient resumes his/her normal lifestyle while being monitored. The patient maintains a log of activity and symptoms over the same time period. The physician then correlates the activities and symptoms to any changes in the heart rhythm.

Angioplasty (PTCA)

An angioplasty is a procedure performed on patients with blocked or clogged coronary arteries. The technique is similar to a catheterization except that a special catheter with a small balloon is inserted into the blockage and inflated in order to compress the plaque and open the artery. A balloon catheter is advanced to the area of your blockage. The balloon is then inflated and deflated several times until the blockage is compressed and the artery is widened.

Directional Coronary Atherectomy (DCA)

A directional coronary atherectomy is similar to an angioplasty except that the blockage is decreased by mechanically removing the plaque.


During an angioplasty, your physician may need to insert a wire coil tube (stent) into the coronary artery. This stent will remain permanently in place to keep the artery open.

Coronary Artery Bypass Surgery (CABG)

A CABG is a surgical procedure that involves the removal of a portion of vein from the leg or the internal mammary artery (located in the chest) and using it to “bypass” the blockage(s) in the coronary artery.

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