Diagnostic Heart Tests

John C. Lincoln Hospitals offer a wide range of diagnostic heart tests for our patients. These tests can help a doctor confirm the presence of a heart condition, as well as help detect changes in an already diagnosed condition.

From blood tests to X-rays, our patients may encounter any of these common diagnostic heart tests during treatment:

Blood Tests

Blood tests play a very important role in confirming — or ruling out — heart conditions such as coronary artery disease and heart failure. Blood tests can measure these and other biomarkers:

  • B-type natriuretic peptides (BNP) are produced by the heart to help the body eliminate fluids, such as sodium, from the body. High levels of BNP can signal damage to the heart muscle and heart failure.
  • Blood urea nitrogen (BUN) tests for elevated levels of urea nitrogen, a sign of kidney failure. BUN is often tested when heart failure is suspected.
  • C-reactive protein is produced by the liver in response to injury (inflammatory disease). High levels of C-reactive protein can signal atherosclerosis (narrowing of the arteries).
  • Enzymes: When damaged, a heart may release enzymes such as creatine kinase (CK on a lab report), creatine phosphokinase (CPK), lactic dehydrogenase (LDH), troponin (cTnT and cTnI) and myoglobin. Elevated enzyme levels indicate whether a heart attack has occurred, and predict heart disease risk.
  • Fibrinogen is a protein that helps the blood clot; high levels of fibrinogen can indicate a risk of a blood clot, resulting in heart attack or stroke.
  • Glucose (Blood Sugar): High levels of glucose can indicate diabetes, a major risk factor for coronary artery disease.
  • Homocysteine is a protein that builds and maintains tissue; too much homocysteine can increase risk of stroke and coronary artery disease.
  • Lipids: A lipid panel (also called a lipid profile) offers a reading on fats (lipids) in the blood stream. Elevated lipid levels can help predict risk for heart attack and heart disease.

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CT Scans

Computed tomography (CT) scans use advanced X-ray technology to produce high-resolution, three-dimensional images of the heart and surrounding arteries. During a cardiac CT scan, X-rays pass through the body in a sequence of slices. A nearby scanner detects the X-rays and creates three-dimensional, cross-section images. The test can be used to locate arteries that are narrowed or blocked by plaque, investigate congenital heart disease and evaluate the heart prior to surgery.

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Cardiac Catheterization

In a cardiac catheterization, a thin, flexible tube (called a catheter) is guided through a major artery to the heart. This allows a doctor to measure blood pressure, blood oxygen levels and the heart's overall pumping strength. A contrast dye, which appears on X-rays, may be injected into the blood. If arteries near the heart are blocked or narrowed by plaque — deposits of fats and other substances (a condition called coronary artery disease) — these obstructions can be removed immediately.

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Coronary CT Angiogram

A coronary CT angiogram is an angiogram performed on a computed tomography (CT) scanner. A contrast dye is injected into the blood stream. Using advanced X-ray technology, the scanner detects the presence of dye and produces high-resolution, three-dimensional images of the heart and surrounding blood vessels. A coronary CT angiogram enables doctors to see into arteries narrowed by plaque and calcium deposits.

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Using high-frequency radio waves, called ultrasound, an echocardiogram enables doctors to assess the size, structure and function of the heart as it pumps blood. This painless, noninvasive test can help detect heart disease and determine whether medications and treatments are effective. Cardiac ultrasound is essentially the same technology used for seeing into the womb. Small pads with electrodes are placed on the patient's chest. To produce video images, a wand, called an ultrasound transducer, is moved across the chest.

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Ejection Fraction Testing (EF)

Typically performed with an echocardiogram, an EF test measures how much blood remains in the heart's pumping chambers (ventricles) after each heartbeat. EF is calculated by comparing blood volume pumped from the heart's ventricles with the blood remaining in a ventricle at the end of a contraction. A normal EF rate for the ventricles is 50% to 70%. A reading of lower than 40% can confirm heart failure.

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Electrocardiogram (ECG)

An electrocardiogram (ECG) measures the heart's electrical activity. Electrodes are taped to the patient's chest, arms and legs. Wires send signals to a device graphs electrical impulses. An ECG can help assess heart rhythm, check blood flow to the heart, diagnose heart attack and investigate irregularities of the heart muscle. An ECG may be given with exercise (an "exercise ECG") and at rest (a "resting ECG").

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Electrophysiology (EP) Study

An EP study investigates the electrical patterns of the heart. It can be helpful in determining the cause of an abnormal rhythm of the heart (arrhythmia). In a typical procedure, a catheter is guided along a blood vessel to the heart. At the end of the catheter, tiny electrodes gather data on the heart's electrical signals. These electrodes also transmit electrical impulses to the heart muscle, to either trigger or turn off an abnormal heart rhythm, or pinpoint the source of incorrect electrical signals. An EP study can be followed by radiofrequency ablation, a procedure that delivers high-energy electrical signals, to heat up and inactivate abnormal heart tissue.

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Exercise Stress Tests

An exercise stress test provides readings of heart activity during and after exercise. A doctor can see how well the heart performs under stress and identify problems that may not be apparent when the heart is at rest. To perform a stress test, a patient walks on a treadmill or rides a stationary bicycle, to make the heart work harder. Electrodes are taped to the chest; wires convey a reading of electrical activity to a nearby electrocardiogram (ECG) machine.

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Holter and Event Monitoring

Holter and event monitors are ongoing electrocardiogram (ECG) tests that track when a heart is beating too fast, too slowly or in an irregular manner. Electrodes are taped to a patient's chest; a portable device — the size of a cellphone — records heart activity.

A Holter monitor is typically worn in a pouch around the waist for a day or two, to continuously record heart activity. If a patient experiences an irregular heart rhythm, he or she can press a button to record symptoms, which are analyzed by an arrhythmia specialist later. By contrast, an event monitor is worn for weeks or months. The device will record heart activity only when activated by the patient — when he or she experiences symptoms.

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Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a noninvasive, painless method for evaluating the heart's structure and function. A strong magnetic field and radio waves create high-definition, three-dimensional pictures of the heart and chest while the heart beats. A computer will analyze changes in energy as magnetic force reaches body tissue. Cardiac MRI can be very helpful in identifying numerous irregularities of the heart muscle and heart valves, as well as inadequate patterns of blood flow (ischemic heart disease). MRI does not use radiation.

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Tilt-Table Testing

Tilt-table testing measures how well the body's nervous system regulates blood pressure and heart rate. A patient is secured to a table in a horizontal position. The table is then tilted, with patient's head up, at 60 degrees for 5 minutes. Abnormal blood pressure may signal the need for a pacemaker.

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Transesophageal Echocardiogram (TEE)

A standard echocardiogram (ECG) uses ultrasound waves to produce images of the heart; a machine converts the echoes of sound waves into images. In a TEE, the ultrasound is guided down the esophagus, producing even more detailed, close-up images of the heart's valves and chambers, without obstruction from the ribs and lungs. TEE can help find blood clots in the heart's filling chambers (atria), which result from atrial fibrillation. TEE may be given before electrical cardioversion or radiofrequency ablation procedures.

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Ultrasound and Vascular Ultrasound

Ultrasound uses high-frequency sound waves to create graphic images of the heart and blood vessels. As sound waves bounce off these tissues, they are converted into images. The technology is proven, noninvasive and painless; it is the same procedure used for seeing into the womb.

Ultrasound can produce moving images of the pumping heart, as well as the direction and prevalence of blood flow throughout the body's arteries. For these reasons, ultrasound is a leading test for peripheral vascular disease, a condition in which plaque deposits develop in the arteries of the neck, arms and legs.

Vascular ultrasound — also called a duplex study — examines blood circulation in the arms and legs. The test can calculate the speed of blood as moves through blood vessels. In a heart mapping procedure, it can highlight one or more blood vessels that require a bypass graft.

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X-rays, one of the first diagnostic imaging techniques to be invented, can still play an important role in detecting heart conditions. Chest X-rays can help diagnose congestive heart failure. They can also show heart infections, enlargement of the heart and even sometimes calcified heart valves or coronary arteries.

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