A Heritage of Loving Service: The Sisters of St. Joseph of Carondelet in Tucson
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Heritage: The Story of St. Mary's Hospital, 1880-1980
By Leo G. Bryne and Sister Alberta Cammack, C.S.J

Chapter III Contemporary St. Mary's
Cardiovascular Laboratory

Perhaps in no other department is the use of specialized equipment and techniques so evident as in the Cardiovascular Laboratory. To doctors, pinpoint diagnosis of coronary problems is as important as the surgery necessary to correct them. The electrocardiogram (EKG) is one of the most important tests in the diagnosis of various heart diseases. One of its essential roles is to recognize abnormal heart rhythms and to assess the function of artificial pacemakers. Along with this, Holter monitors can be worn by patients which give twenty-four hour print-outs of EKG tracings recorded on small cassettes.

In stress testing, a patient is subjected to increasing degrees of physical activity on a treadmill. Because of the correlation of increased activity with the need of the heart muscles for more oxygen, stress testing is used as a means of assessing the degrees of obstruction in the coronary arteries which supply blood oxygen to the heart muscles. Normal heart rates calibrated to the amount of exercise have been set up as a standardized scale. Deviations from the scale, which show up on the EKG readings, are significant indications of coronary arterial obstruction or coronary insufficiency, a condition which often leads to a serious heart muscle problem.

In 1967, the first X-ray movies came with the cineradiographic equipment which consists of a movie camera attached to an X-ray image intensifier. The intensifier increases light to be captured on highly sensitized film. Although used in other studies, this equipment proves especially effective in cineangiography, a procedure in which a catheter is slipped through a main artery of the arm or leg and moved under fluoroscopy toward the heart. When in place, dye is injected through the catheter into the right and left coronary arteries. Guide wires within the polyurethane catheter tubes help with the placement. Fluoroscopic images are shown on the TV monitor in the Lab and also in the adjacent instrumentation room where a cardiovascular technician monitors blood pressure and heart sounds. The physician carefully controls the dye injection process as to the amount and pressure. The time needed for the dye to pass through certain portions of the circulatory system helps to indicate the amount and speed of blood flow. Within the heart itself, the opaque dye enables the physician to see the structural configurations of the heart and its blood vessels. The film shown on the TV monitor gives the doctor a picture of the heart's activity. The film is stored as part of the patient's medical record and can be later viewed at various speeds and with stop-framing whenever the doctor wishes to review the findings for more intensive observation and study.

Pressures and oxygen concentrations within the heart can also be measured by using catheters with no need for dye injections. Such procedures give the physician a better understanding of the patient's cardiac condition. A heart block, or the site of nonconduction of the heart's contraction impulses is located by two electrodes placed via catheters in the right atrium and right ventricle which permit sequential readings of electrical activity.

The Echocardiograph, which was acquired in 1977, is among the latest types of cardiovascular diagnostic equipment. By echocardiographic studies of the valves and chambers of the heart, it is possible to detect structural and functional abnormalities. High-frequency sound vibrations are emitted and received while instrument adjustment ensures the best possible definition of structures. With the Echocardiograph, it is possible to define cardiac chambers and great vessels, to detect pericardial effusion, and to evaluate certain aspects of ventricular functions. Long periods of training and experience are necessary to develop proficiency both in performing the studies and in interpreting the cardiographic records.

Continue with Chapter III: Contemporary St. Mary's Outpatient Surgery

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