Non-Invasive Diagnostic Services
RUSH Oak Park Hospital offers several non-invasive methods to diagnose cardiac problems. These simple procedures can quickly identify blockages or other areas of concern.
Exercise Stress Test
Using an electrocardiogram (EKG), the patient's heart is monitored at rest and then during graduated treadmill exercise. Level of fatigue, blood pressure, heart rate, and EKG response to the exercise are monitored. Changes on the EKG during exercise may indicate an abnormality, such as blockage in an artery, that prevents adequate blood flow to the heart when exercise increases the demand for higher blood flow.Stress Echocardiography
The echo technique uses sound wave energy to take ultrasound images of the heart's walls and valves. Attention is given to each wall of the heart and how it moves. If the heart wall is difficult to see clearly, a contrasting agent can be injected to improve visualization. Exercise stress is then performed as described above. If a patient cannot exercise well due to arthritis or other physical limitations, medication can be substituted to increase the heart rate to a predetermined target based on the person's age. Repeat echo imaging shows how the heart contracts when stressed. If a blockage in an artery prevents adequate blood flow during the increased metabolic demands of the stress test, the wall of the heart that artery supplies doesn't contract as well as the other walls of the heart and will show up as abnormal.Cardiac Nuclear Imaging
Nuclear Cardiac Stress Test. An intravenous line is placed and an exercise stress test is performed as described above. At peak exercise, a small dose of a nuclear tracer is injected into the blood stream and is taken up in proportion to the blood flow. A scan is performed soon after to "visualize" the blood flow to the heart under the stress condition, and is compared to another scan obtained under resting conditions. Comparison of the two sets of images can indicate possible blockage or scarring in the heart arteries. This test also allows evaluation of how strongly the heart pumps (similar to a MUGA scan). If a patient is unable to exercise due to arthritis or other physical limitations, medication can either increase the heart rate or dilate the heart arteries to create conditions where variations in blood flow (blockages) can be discovered.
MUGA (Multiple-Gated Acquisition) Scan. A small amount of a nuclear tracer is injected into the bloodstream and is taken up by the heart. The heart can be imaged in the scanner showing how much blood is pumped with each heart beat. This allows very accurate determination of how strong the heart is. The test does not require exercise or other forms of stress.
