Heart Tests: Sorting Out What is Best
Blocked heart arteries are the ultimate cause of heart attacks (myocardial infarction). Let's take a look at symptoms and what tests are best to discover and treat this serious health risk.
Who's at risk?
Because these blockages occur slowly over a parson’s lifetime, many people do not have any symptoms until the blockage causes at least 70 percent narrowing in a blood vessel. Another cause of heart attack is caused by a lesser degree of blockage that becomes inflamed and results in the separation of the plaque from the wall of the blood vessel resulting in a clot (plaque hemorrhage).
People at risk for heart attack include those with elevated lipids (cholesterol and triglycerides) patients who smoke, those with diabetes, overweight individuals -- especially with poorly controlled blood pressure (hypertension) -- and individuals of certain ethnic backgrounds, particularly Asian and Hispanic patients with any of the above risk factors.
A strong family history of heart disease, especially at a young age in a sibling or parent, also increases the risk; The more of these factors that are present in an individual increases the risk of heart and vascular disease.
Symptoms in men and women
Symptoms occur when there is increased workload on the heart brought on either by physical or emotional stress, or a combination of the two. Because the heart is a muscle, physical activity such as shoveling snow or running a vacuum cleaner puts more demand on the heart to increase blood flow, which in turn raises the need for oxygen being supplied to the heart muscle. Stress also puts more demand on the heart and related activity may produce symptoms associated with a decrease in blood flow to the heart muscle.
We all have heard that women and men often experience different types of symptoms. Typically, a dull aching sensation or pressures in the center of the chest are symptoms, which need to be addressed. Some people have described symptoms that feel like "an elephant sitting on my chest” or "my chest was in a vice."
Both women and men may experience a burning sensation or indigestion, which is unlike any symptoms that the patient has experienced previously. Some women waken in the middle of the night complaining of a “smothering sensation” or of pain in the jaw, shoulder or arm, unlike any pain associated with a specific cause or injury. A sharp or stabbing sensation or symptoms that are related to a certain movement are usually not associated with heart attacks.
What should I do if I am concerned about a heart attack?
Your doctor will examine you and take a family history and ultimately assess your risk based on factors such a smoking, blood pressure, diabetes, increased lipids and body weight.
Because symptoms occur when there is increased demand placed on the heart, a stress test also may be helpful. The goal of a stress test is to measure heart activity before and during exercise when the heart rate increases. Running on a treadmill is one way to measure this, but because many people cannot walk fast enough or run on a treadmill, a chemical stress test is recommended. For this test an injection in a vein is given vein that speeds up the heart while the doctor watches an EKG. Sometimes an isotope is injected to measure distribution in the heart muscle. This is called a nuclear stress test. Another test is called a stress echocardiogram, which uses ultrasound to observe changes in contraction of the heart muscle during exercise.
Nuclear stress test
A nuclear stress test uses an isotope, usually technetium or thallium, which distributes during exercise and washes out after a period of time. By correlating the uptake and washout phase of the test, assumptions are made as to whether or not blockages are present. The sensitivity of this test is about 90 percent while the specificity is 71 percent. Thus, some patients with blockage will be missed. In these cases, if the doctor has a high degree of suspicion, a heart catheterization is recommended to take actual pictures of the circulation and to measure the degree of blockage present. This test carries some risk since radiation is involved and repeating the test leads to a cumulative dose of radiation exposure in a patient’s lifetime.
Stress echocardiogram
A stress echocardiogram compares the heart contraction at rest versus during exercise and the cardiologist then predicts contraction deficits, which correlate with areas of decreased blood flow in the heart muscle. This test is very sensitive and does not expose the patient to radiation. If positive, the physician then recommends a heart catheterization. During both exams, an EKG is monitored and correlation with electrical activity is made, another indicator that there may be a problem with blocked arterial flow.
Coronary CT scan
A coronary CT scan is a newer and very sensitive way to visualize blocked arteries in the heart, but it is sometimes overly sensitive in finding plaque, which is not yet resulting is severe obstruction. This test also exposes the patient to radiation in quantities similar to the nuclear stress test.
If these tests are positive, a cardiologist will recommend a heart catheterization. This involves passage of a small plastic tube inserted into the heart circulation, either from the wrist of from the femoral artery in the patient’s groin. If a single blockage is found, the cardiologist will place a balloon into the artery to stretch and compress the plaque followed by a stent, which is a very small metal scaffolding to support the artery. Patients will then need to be on medications to prevent the stent from closing and the patient's doctor will discuss how to avoid recurring heart blockages based on lifestyle modifications for that person.
Because lifestyle modifications have been shown to improve one's risk for developing heart disease, it would benefit us all to act proactively to prevent the problem in the first place. Smoking cessation, exercising at least 30 minutes five times a week, eating proper diet and reducing one's weight are all important to help prevent problems before or after heart attacks occur.
James A.M. Smith, DO, is board certified by the American Board of Vascular Medicine and the American College of Osteopathic Internists. He practices cardiovascular medicine and intervention at Kansas Vascular Medicine.
