How is coronary artery disease diagnosed?
The resting electrocardiogram (EKG) is a recording of the electrical activity of the heart, and can show changes indicative of ischemia or heart attack.
- Often, the EKG in patients with coronary artery disease is normal at rest, and only becomes abnormal when heart muscle ischemia is brought on by exertion; therefore, exercise treadmill or bicycle testing (stress tests) are useful screening tests for patients with significant coronary artery disease (CAD) and a normal resting EKG. These stress tests are 60 to 70% accurate in diagnosing significant CAD.
- If the stress tests are not diagnostic, a nuclear agent (cardiolyte or thallium) can be given intravenously during stress tests.
- Addition of one of these agents allows imaging of the blood flow to different regions of the heart, using an external camera.
- An area of the heart with reduced blood flow during exercise, but normal blood flow at rest, signifies substantial artery narrowing in that region.
- Stress echocardiography combines echocardiography (ultrasound imaging of the heart muscle) with exercise stress testing.
- It is also an accurate technique for detecting CAD.
- When a significant narrowing exists, the heart muscle supplied by the narrowed artery does not contract as well as the rest of the heart muscle. Stress echocardiography and thallium stress tests are 80% to 85% accurate in detecting significant CAD.
- When a patient cannot undergo an exercise stress test because of neurological or arthritic difficulties, medications can be injected intravenously to simulate the stress on the heart normally brought on by exercise. Heart imaging can be performed with either a nuclear camera or echocardiography.
- Cardiac catheterization with angiography (coronary arteriography) is a technique that allows x-ray pictures to be taken of the coronary arteries.
- It is the most accurate test to detect coronary artery narrowing.
- Small hollow plastic tubes (catheters) are advanced under x-ray guidance to the openings of coronary arteries.
- Iodine contrast "dye," is then injected into the arteries while an x-ray video is recorded.
- Coronary arteriography gives the doctor a picture of the location and severity of narrowed artery segments.
- This information is important in helping the doctor select medications, PTCA, or coronary artery bypass graft surgery (CABG) as the preferred treatment option.
- Stents are inserted into narrowed coronary arteries to help keep them open after balloon angioplasty. The stent then allows the normal flow of blood and oxygen to the heart.
- Stents placed in narrowed carotid arteries (the vessels in the front of the neck that supply blood to the brain) appear useful in treating patients at elevated risk for stroke.
- Stents are also used in other structures such as the esophagus to treat a constriction, the ureters to maintain the drainage of urine from the kidneys, and the bile duct to keep it open.
- Named for Charles R. Stent (1845-1901), an English dentist.
- Coronary arteries are the vessels that supply the heart muscle with blood rich in oxygen.
- They are called the coronary arteries because they encircle the heart in the manner of a crown.
- The word "coronary" comes from the Latin corona and Greek koron meaning "crown".
- Like other arteries, the coronaries may be subject to arteriosclerosis (hardening of the arteries).
- There are a number of coronary arteries.
- Those most often bypassed today include the right coronary artery, the posterior descending coronary artery, the left main coronary artery, the left anterior descending coronary artery and the left circumflex coronary artery. Plaques obstructing the coronary arteries may also be treated by balloon angioplasty, stents, and other techniques.
More information about angioplasty; as well as, the stent is located at the following links:
Angioplasty Info and the Stent, Part 1
Angioplasty Info and the Stent, Part 2
Angioplasty Info and the Stent, Part 4
Angioplasty Info and the Stent, Part 5
Angioplasty Info and the Stent, Part 6
Angioplasty Info and the Stent, Part 7