Testing for heart blockages
How is the heart initially tested?
One of the first tests done on a suspected heart patient or one that is included in an executive medical check-up is called Stress Test. Also called Exercise Test or Treadmill Test, this procedure is medical examination performed to detect any signs of coronary heart disease, blockages in the coronary arteries and/or heart irregularity, or even impending heart attack.
How is this test done?
The Stress Test is done with the patient walking on a treadmill while he/she is wired and hooked up to the electrocardiogram machine to monitor his heart rate, its rhythm and the shape or configuration of the EKG tracings. Changes in the shape of the EKG complexes will show if the heart is suffering from lack of blood supply due to blocked coronary arteries. The treadmill speed could be increased and the level could be adjusted to provide a simulated uphill walk (more stress for the heart).
What is a Stress Echo?
Stress Echocardiography, or Stress Echo for short, is a treadmill exercise test that shows how well your heart pumps when made to beat faster and harder. A transducer (a small hand-held device that produces sound waves) is placed on the chest before and immediately after the treadmill exercise. The sound waves bounced off the heart and changed into actual pumping heart images on a video screen. The doctor compares the two images to detect any changes in the manner the heart responds to stress, which also shows whether the heart is getting enough blood (oxygen) to meet its increased demand for (blood) oxygen during the exercise or exertion.
Can’t regular EKG not detect this heart problem?
Regular resting electrocardiogram (with the patient at rest) is only useful if it is positive, if the patient just suffered an acute heart attack, or where actual heart attack is in progress. If the resting EKG is reported as “normal” or negative, it does not mean much. Many patients with “normal” EKG have been found to have severe blockages of their coronary arteries. The heart must be put under stress in order for the heart to really “complain.” An analogy is a car engine that sounds fine while idling, but knocks when is running.
How accurate is the Stress Test?
Treadmill or Stress Test has about 70 to 78 percent sensitivity. When done with Thallium (known as Thallium Stress Test), which is the preferred technique to do it, the sensitivity increases to a range of 85 percent to 95 percent. An alternative to the Treadmill Test is the use or coronary artery dilators (arterial channel openers), Dipyridamole (commonly known as Persantine) given intravenously, for those who
cannot walk on the treadmill because of obesity or arthritis. This drug increases flow to the normal coronary arteries but not to the coronary arteries that are blocked, hence the Imaging taken about 3-5 minutes after the dipyridamole is injected will show areas of the heart that are not receiving adequate blood supply, indicating blocked coronary arteries. The imaging is done using SPECT (Single Photon Emisson Computed Tomography). The sensitivity of this radionuclide imaging is 80-85%, and specificity greater than 90% for coronary artery disease.
Who should have a Stress Test?
As a general rule, persons who are over 40 years old (especially cigarette smokers), with or without symptoms, those with a strong family history of coronary heart disease, those whose work entails a lot of stress and tension, and those with chest pains are candidates for a yearly Thallium Stress Test. This test is so useful it has saved countless lives, which could have been lost, were it not for the availability of this valuable technology. It is so simple and yet so effective.
If the Stress Test is normal, then what?
If the reason for the Stress Test was because of chest pains, then a normal Stress Test will provide the peace of mind that the pains were most likely not anginal (heart) pains. If the findings are equivocal, an ECHO may also be performed for confirmation. If the test was taken for preventive reason, then the following lifestyle changes are recommended for better health maintenance: (1) if a smoker, quit smoking; (2) do a regular physical exercise regimen; (3) stay on low cholesterol diet (minimizing intake of eggs and red meats), basically eating fish, white chicken meat, vegetables, whole grains, nuts, and fruits and other high fiber foods; (4) have a regular schedule of rest and relaxation to unwind and reduce stress; (5) have a yearly medical check-up; and (6) if you are on any medication prescribed by your physician, take them religiously.
What if the Stress Test is positive?
If the Stress Test is positive, some cardiologists might do a Stress Echocardiogram or proceed to recommend a Cardiac Catheterization to find out which coronary arteries are blocked and how severe the blockages are. This will also show how much damage, if any, the heart muscles have suffered due to these blockages. Cardiac Catheterization is the “supreme court” of diagnostic tests for coronary heart disease. It will tell us 100% if there is any significant blockages or not. Other tests will only give some clues, but heart catheterization is absolutely revealing and decisive.
How can Stress Test prevent a heart attack?
Stress Test is a tool that can facilitate the early diagnosis of probable blockages in the coronary arteries. Early detection could obviously lead to prompt medical care, thus minimizing the chances of an actual heart attack.
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