Cardiac and Pulmonary Function Testing

Cardiac Function Testing

Echocardiogram (ECHO) produces, via sound waves, a moving image of the beating heart on a video screen. The physician can analyze the heart’s thickness, size, and function, as well as the motion pattern and structure of the four heart valves. ECHO is helpful in detecting damage and disease to the heart. The technician prepares the chest area by applying a conductive gel, and then places a small device called a transducer on the patient’s chest. An image of the area is viewable on a video monitor. An ECHO takes about 30 minutes.

Multigated Acquisition (MUGA) Scan uses radionuclide imaging to provide information about blood flow, how well the heart is pumping, and the functioning of lower heart chambers (ventricles). A very small amount of a radioactive isotope (tracer) is administered intravenously, and then a gamma camera is used to produce clear images of the heart tissues. The tracer usually is eliminated harmlessly from the body within 48 hours. There can be slight discomfort at the needle site. The procedure takes about 40 minutes.

Electrocardiogram (EKG) graphically records the heart’s electrical activity, providing important information about the heart’s rate and rhythm, and the presence of past or current heart attacks. EKGs are routine tests that are non-invasive, quick, safe, painless, relatively inexpensive, and do not use radiation. To perform an electrocardiogram, a technician applies gel to ten cleaned areas on the chest. Small metal electrodes are then applied and connected by wires to the electrocardiograph machine. The patient must lie perfectly still for about one minute as resting-heart activity is measured and recorded. Each electrode produces a “tracing” or “lead” of a particular area of the heart and its activity. The entire EKG takes 5–10 minutes.

Pulmonary Function Testing

 

Spirometry measures breathing capacity and flow rates. The patient inhales maximally and exhales forcefully and completely, and then immediately inhales maximally into a device called a spirometer.

Lung Volumes measure the total amount of air in the lungs and capacity volumes of the lung compartments. Lung volumes may be done using the following techniques:

Body Plethysmography: The patient sits in a clear chamber and breathes on a mouthpiece. During the test, the patient is asked to inhale against a closed shutter for 2 seconds, 2–3 times. At the end of the measurements, the patient performs a slow maximal inhalation followed by a maximal exhalation.

Helium  Dilution:   The patient breathes a helium gas mixture for 3–7 minutes and then performs a slow maximal inhalation followed by a maximal exhalation.

Single-Breath Diffusing Capacity (DLCO)   measures the ability of the lungs to transfer oxygen into the bloodstream and   carbon dioxide out of the bloodstream. The patient is asked to exhale maximally, followed by maximal inhalation of a test gas. The patient is asked to hold the breath for 10 seconds, followed by an exhalation. This is repeated 2–3 times.

Arterial Blood Gas measures the amount of oxygen and carbon dioxide and the pH of an arterial blood sample. Most often a small sample of blood is drawn from the radial artery in the wrist. These tests require some effort on the part of the patient, who must work cooperatively with the technician. The procedure takes 30 minutes to an hour.