Expert diagnosticians use echocardiography to perform non-invasive diagnostic testing of the heart using high-frequency sound waves (ultrasound) to produce a moving image of the heart in action. This procedure allows the physician to evaluate the heart’s structure and function. It can show how the valves are working, provide information about the thickness of the valves and how they are moving, and how blood is flowing through the heart, as well as provide information about the arteries.
A wand-like instrument, called a transducer, that emits the sound waves, is moved over the patient’s chest or placed on the patient’s ribs near the breast bone and directed toward the heart. The transducer picks up the echoes of the ultrasound waves as they bounce off the heart structures. The echoes are converted into images on a monitor to produce moving pictures of the heart. This is the same as the sound monitoring used during pregnancy. A variety of techniques can be used to: view the left side (or main pumping chamber) of the heart, expand the view to take in the entire heart or measure blood flowing through the arteries and show the pattern of flow through the heart.
When it is difficult to get a clear picture of the heart using standard echocardiography, transesophageal echocardiography (TEE), may be used. Like standard echocardiography, TEE uses ultrasound waves to produce an image of the heart and to see how it is functioning. But unlike standard echocardiography, the sound waves travel through a tube-like device put in the mouth and passed down the throat into the esophagus (the tube that connects the throat to the stomach). Because the sound waves originate so much closer to the heart and do not have muscle and bone in the way to create interference, the pictures are clearer and can show doctors the detailed size, shape and movement of the heart muscle, the condition of the coronary arteries; how the heart valves are working; and how blood is flowing through the heart.
Intracardiac Echocardiography (ICE)
ICE is a combination of echocardiography and angiography that uses high frequency sound waves (ultrasound) to produce a moving picture of the heart. The sound waves are produced by a miniature transducer that is located at the end of a catheter. This catheter is introduced through a small incision in the groin area into a vein and threaded up to the chambers on the right side of the heart. ICE is primarily used during repair of congenital defects of the septum (see ASD/VSD) repair) and during electrophysiology procedures to precisely landmark areas of abnormal conduction that can then be treated (see ablation.)
Intravascular Ultrasound (IVUS) or Intracoronary Ultrasound
A variant of coronary angioplasty, IVUS creates a detailed cross-sectional view of a coronary artery instead of a silhouette image. This allows greater precision when determining the size, structure and distribution of a blockage. As in coronary angioplasty, a catheter is introduced into the arterial system through an incision in the groin and threaded through the arterial system to the origin of the coronary artery. A tiny ultrasound device is then introduced through this catheter and threaded into the coronary artery. As the catheter is advanced through the vessel, ultrasound waves are reflected off the vessel walls and are picked up creating a two dimensional image of the lumen (opening) of the vessel. Any narrowing of the opening or thickening of the walls can be seen on a television screen connected to the device.
While angiography is still considered the standard for diagnosing obstructions of the coronary arteries, IVUS can be a useful tool in evaluating questionable blockages in the vessels.