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State-of-the-Art Diagnostic Services

If you are concerned about your heart health, Centegra Health System offers a wide variety of cardiac diagnostic tests. These services are used to find irregularities in the heart. Most tests are non-invasive and provide accurate reports about your heart function and behavior.

Centegra is committed to the cardiovascular health of greater McHenry County residents. Our echocardiography lab is accredited by the Intersocietal Commission for the Accreditation of Echocardiography Laboratories (ICAEL). Centegra’s Chest Pain Centers were the first accredited chest pain centers in the region.

Cardiovascular Diagnostic Tests Available at Centegra


Angiography is a minimally invasive diagnostic procedure performed by a highly skilled cardiologist in one of three cardiac catheterization labs at Centegra. To learn more, visit the Cardiac Catheterization page.

MCOT (Mobile Cardiac Outpatient Telemetry)

This monitor consists of wearing three electrodes over a period of seven to 30 days. It is commonly used for the detection of cardiac arrhythmias (irregular heartbeats) or to explain loss of consciousness, dizziness, or palpitations. The MCOT differs from an event monitor in that there is actual real-time monitoring of your heart rhythm 24/7. The MCOT monitor often is worn for a shorter duration than an event monitor since monitoring is continuous, allowing for easier detection in rhythm changes.

Echocardiogram (ECHO)

HeartRhythmAn echocardiogram is an ultrasound of the heart. This half-hour exam shows the interior structures and walls of the heart as it is beating.


An electrophysiology (EP) study is a procedure that tests the electrical conduction system of the heart to assess its electrical activity and conduction pathways. The study is used to investigate the cause, locate the origin, and select the best treatment for various abnormal heart rhythms. This type of study is performed by a specially trained invasive cardiologist, called an electrophysiologist.

Event Monitor

An event monitor is a portable device that uses electrodes to monitor the heart. It is similar to a holter monitor, but monitoring can be for a longer duration, often between 10 and 30 days. The monitor only records if an “event” button is pushed to record a symptom. An event monitor is used for patients with less frequent symptoms.

Holter Monitor

A holter monitor is a small, portable device that uses electrodes to continuously monitor the heart on a short-term basis, usually between 24 to 48 hours. A holter monitor also evaluates your heart rate and rhythm. This test is commonly ordered because of complaints of palpitations, light-headedness, or cardiac arrhythmias.

Stress Tests

Exercise Tolerance Stress Test

Commonly called a stress test, this is a procedure that records blood pressure and the heart’s electrical activity (ECG) during exercise. The exercise is done on a treadmill.

Stress Test with Nuclear Medicine Imaging

In this diagnostic test, heart scans are performed immediately following exercise, which can help locate areas of your heart muscle that may have reduced circulation. A small IV is inserted so that a radioactive substance can be injected during exercise. About 15 to 30 minutes after exercise, you will be asked to lie still while a scanner takes pictures of your heart while both arms are raised above your head. You may be asked to return the following day for a second resting scan.

Medication Stress Test with Nuclear Medicine Imaging

If you are unable to exercise on a treadmill, a special medication called Lexiscan or Dobutamine can be used as an alternative to exercise. You will also have pictures taken of your heart about 45 to 60 minutes after the medication test is done. You may be asked to return the following day for a second resting scan.

Stress Echocardiogram with Exercise or Medication

If your doctor has ordered a stress echocardiogram, the ultrasound technician will obtain ultrasound images of your heart both before and immediately after exercise. Medication can also be used as an alternative to exercise.

Tilt Table Test

A tilt table test is a non-invasive test to help aid in the diagnosis of common symptoms such as dizziness, loss of consciousness, or changes in heart rate and blood pressure. Continuous monitoring of your heart rate and blood pressure are performed while you stand almost upright on a specialized table. An IV will be inserted for this exam.

Transesophageal Echocardiogram (TEE)

This test is an alternate way to perform an echocardiogram of the heart. This procedure involves passing a special probe into your esophagus, while you are sedated, to view any structural abnormalities of the heart. 3D images can be obtained to get a better view of the hearts anatomy.

Cardioversion (DCCV)

A Cardioversion is performed to convert your hearts rhythm back to a normal rhythm for patient’s who have Atrial Fibrillation or Atrial Flutter. You will be sedated during this procedure and an electrical current will be sent through pads to “shock” your heart in normal rhythm. This exam is sometimes preceeding with a TEE to ensure there are no blood clots in your heart prior to cardioverting.

For answers to your questions about the diagnostic tests available in McHenry or Woodstock, visit the Heart Center FAQ page or call (815) 759-4050.