Some patients, especially with sporadic symptoms, may be asked to wear a portable monitor for a continuous recording. A stress test is an EKG taken during exercise, usually on a treadmill or stationary bike, sometimes until symptoms occur. Stress tests diagnose the cause of chest pain, assess abnormal heartbeats, monitor the effectiveness of drugs and evaluate the safety of beginning an exercise program, especially after a heart attack or surgery. This test uses sound waves to produce a moving picture of the beating heart. Color-flow Doppler ultrasound uses frequencies that bounce off red blood cells to calculate the velocity of blood flow through the heart.
Different rates show up as different colors, revealing obstructed areas.
Doppler ultrasound also can evaluate blood flow in arteries and veins. A thin tube called a catheter is inserted into a blood vessel and guided to the heart while the patient is awake but sedated. Then, a contrast solution is injected so the heart and its major blood vessels will show up on an X-ray. The test reveals heart defects and clogged arteries.