San Juan Regional Cardiology

Heart Tests–From Simple to Sophisticated

How healthy is your heart? Most Americans assume their heart is in pretty good shape until something happens to tell them otherwise–severe pain in the chest, inability to exercise without shortness of breath...or a heart attack. Heart disease is the number one killer of both men and women in this country, often striking without prior warning. Based on studies of the blood vessels of young persons who died of other causes, doctors know that heart disease often develops at a young age, silently laying the groundwork for a disabling or fatal heart attack several decades later.

The ideal, of course, is to know what´s happening inside the heart and blood vessels so that problems can be headed off early. And there are numerous tests–some simple and others technologically sophisticated–that can do just that.

One of the easiest and most effective is one that your doctor or nurse probably performs every time you visit, whether the problem is heart-related or not–a reading of your blood pressure. High blood pressure–anything greater than 120/80–can be a sign of early developing heart disease. And, if left uncontrolled, it causes irreversible damage to both the heart and blood vessels. Fortunately, blood pressure is easily controlled with diet, exercise and medications.

High cholesterol may be an even more important risk factor for heart disease, and cholesterol testing is recommended at least once every five years for adults age 20 and over and more frequently after age 50. A complete lipid profile–measuring LDL, HDL and triglycerides–can be accomplished with a simple blood test, preceded by several hours of fasting. When cholesterol is mildly elevated, a change in diet and exercise may be recommended. When it´s significantly elevated, or if other risk factors exist, a doctor may prescribe cholesterol-lowering medications.

Doctors now know that damage to arteries (atherosclerosis) involves tissue inflammation that damages blood vessels and leads to the accumulation of fatty blockages. One indication of inflammation is a high level of C-reactive protein (CRP), which can also be measured through a blood test. When high CRP is found, however, there is no certain way to lower it and recent research indicates that this marker may not reveal much beyond what is known about high cholesterol, hypertension or excess weight–risk factors that are usually found in conjunction with high levels of CRP.

While the above blood tests provide a good idea of what´s taking place in the blood vessels, it´s now possible, through CT and ultrasound technology, to get actual images of the arteries and determine how much narrowing has taken place or how much calcium is present in coronary arteries–a more direct indication of disease than cholesterol or blood pressure.

A group of doctors recently recommended that CT and ultrasound scans be used widely as screening tests, but the National Institutes of Health and the American Heart Association are unwilling at this time to include this type of screening in national guidelines. The scans are expensive–costing several hundred dollars–and until more evidence is available, it´s unknown whether they would save lives or lead to treatments that are risky and unnecessary.

For persons at high risk of cardiovascular disease, there are other tests to measure the health of blood vessels. One uses a computer analysis to measure arterial elasticity–how well the blood vessels are able to relax and contract in response to the flow of blood.

Blood pressure taken at rest and then during exercise is another indication of arterial function. A steep rise in blood pressure during exertion can be a sign of reduced elasticity. Measuring blood pressure in the leg as well as the arm (ankle/brachial index) is one way to detect vascular disease in the lower body. When there is a strong suspicion of coronary heart disease, there are tests a physician can use to focus more directly on the heart itself, its rhythms and its pumping action. Uncontrolled blood pressure can strain the left ventricle of the heart, leading to a thickening of the ventricle walls and a weakening of its pumping action. This is known as left ventricular hypertrophy (LVH), and it’s a precursor of heart failure.

One of the most common tests to evaluate the functioning of the heart is a resting electrocardiogram (EKG). It involves placing electrodes on the skin of chest, arms and legs through which a doctor can monitor and record heart rhythms. If abnormalities are found, a left ventricular ultrasound can measure the diameter, mass and wall thickness of the ventricle.

For a person who is experiencing symptoms of heart disease, a normal resting EKG may lead to an exercise stress test–an electrocardiogram performed on a treadmill or a stationary bicycle. This test can determine if there are blockages that are keeping the heart from getting sufficient blood flow during physical activity. Another approach uses a Holter monitor (see description in article above). A person who has had unexplained palpitations or fainting might wear a Holter monitor to help diagnose the problem and monitor the effectiveness of medications.

A nuclear medicine stress test uses a mildly radioactive substance, injected into the body to track blood flow and pinpoint areas of the heart getting insufficient blood flow. It´s more accurate than the standard exercise stress test.

The gold standard for assessing blockages in coronary arteries is angiography. It´s usually performed after a resting or exercise EKG has already indicated insufficient blood flow to the heart. Through angiography, a doctor can identify which arteries are affected and determine whether balloon angioplasty or surgery is required for treatment.

A catheter is inserted into an artery in the groin or arm and guided to the heart through images projected on a video monitor. Contrast material injected through the catheter makes it possible to view abnormalities on x-ray film.

There are many other tests, each with its own specific role in diagnosis and treatment. With technological advances, new tests are constantly being introduced. As valuable as these tests are, the major tools in defeating this major killer remain the same: a health-conscious public who understand the value of diet, exercise and control of blood pressure and cholesterol.