the insertion of a catheter into a vein or artery and guiding of it into the interior of the heart for purposes of measuring cardiac output, determining the oxygen content of blood in the heart chambers, and evaluating the structural components of the heart. It is indicated whenever it is necessary to establish a precise and definite diagnosis in order to determine whether heart surgery is necessary and to plan the surgical approach.

A, Right-sided heart catheterization. The catheter is inserted into the femoral vein and advanced through the inferior vena cava (or, if into an antecubital or basilic vein, through the superior vena cava), right atrium, and right ventricle and into the pulmonary artery. B, Left-sided heart catheterization. The catheter is inserted into the femoral artery or the antecubital artery. The catheter is passed through the ascending aorta, through the aortic valve, and into the left ventricle. From Ignatavicius and Workman, 2002.

During the initial assessment it is important to find out whether the patient has any allergies. The contrast medium used contains iodide salts; if a patient is allergic to iodine or seafood, a contrast medium that does not contain iodine must be used, or antihistamines must be administered before the procedure. A mild tranquilizer or hypnotic may be given just before the procedure to help the patient relax, but a general anesthetic is not used. Patients need to know that they must be awake and cooperative during the procedure. They will be asked to stay in a certain position, cough, breathe deeply, and possibly exercise so that the heart's response to an increased workload can be evaluated. They should be reassured that the laboratory staff is ready and equipped to handle any emergency should the need arise.

Ideally, preprocedure visits by the physician and a member of the staff in the cardiac catheterization laboratory will provide patients with the information they need about the procedure, its purpose, and potential complications. However, because of anxiety the patient may not be able to assimilate the information and will have many questions not asked at the time of the visits. It is then the responsibility of the floor nurses to answer questions as honestly as they can and to provide emotional support and reassurance.

After the procedure the vital signs are checked periodically. It is especially important to check the pulses distal to the insertion site every half-hour for three hours, or as often as required by protocol, to be sure there has been no clotting and obstruction of a blood vessel. The insertion site dressing is changed as needed and the site inspected for signs of infection. Thirst and diuresis are expected because of the effect of the dye used in the procedure. The patient should be encouraged to drink fluids to prevent hypotension and hasten excretion of the dye, which is potentially nephrotoxic. Mild discomfort also is expected and should respond to the prescribed analgesic. If the patient experiences severe pain the physician should be notified.

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Cardiac | definition of cardiac by Medical dictionary