Stress tests save lives


Almost 4 million people in the United States alone have undiagnosed heart disease. According to the US Centers for Disease Control and Prevention (CDC), 735,000 Americans have a heart attack each year, killing 370,000 a year, or about 1,014 per day.

When it comes to a disease as serious as a heart attack, prevention is key, and detecting its presence before it happens is obviously the wisest.

Today’s sophisticated cardiac stress testing is one easy and simple diagnostic aid that is most valuable.

What is a stress test?

A stress test, also called an exercise test or treadmill test, is a 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.

This could be combined with an echocardiogram, radioactive imaging thallium or sestamibi, and even positive emission tomography (PET), depending on each individual need.

How is this test done?

The stress test is done with the patient walking on a treadmill while s/he 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 a 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 a regular EKG not detect this heart problem?

Regular resting electrocardiogram alone (with the patient at rest) is only useful if it is positive, if the patient just suffered an acute heart attack, or when an actual heart attack is in progress. If the resting EKG is reported as “normal” or negative, it does not mean much. Many patients with a “normal” EKG have been found to have severe blockages in 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 three to five 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 Emission Computed Tomography). The sensitivity of this radionuclide imaging is 80-85 percent, and specificity greater than 90 percent 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.

What if the stress test is positive?

If the stress test is positive, some cardiologists might do a stress echocardiogram/isotopic imaging, 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 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?

A stress test is a tool, one of a few, that can facilitate the early diagnosis of probable blockages in the coronary arteries. Early detection of his treacherous cardiac disease could obviously lead to prompt medical care, thus minimizing the chances of an actual heart attack. Countless live have been save by early diagnosis.

Remember, it’s the only heart we’ve got. Let’s take good care of it.

***

Philip S. Chua, MD, FACS, FPCS, Cardiac Surgeon Emeritus in Northwest Indiana and chairman of cardiac surgery from 1997 to 2010 at Cebu Doctors University Hospital, where he holds the title of Physician Emeritus in Surgery, is based in Las Vegas, Nevada. He is a Fellow of the American College of Surgeons, the Philippine College of Surgeons, and the Denton A. Cooley Cardiovascular Surgical Society. He is the chairman of the Filipino United Network – USA,  a 501(c)(3) humanitarian foundation in the United States. Email: scalpelpen@gmail.com

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