1-15
1-15. CARDIAC CATHETERIZATION
This is a procedure in which a radiopaque catheter is manipulated through the heart under fluoroscopic observation. The exterior end of the catheter is connected by a three-way stopcock to a saline filled regulated drip system that also contains a pressure gauge (strain gauge) and a camera. During the procedure the blood pressures within the heart are automatically transmitted to the strain gauge that, in turn, transmits the pressure to the camera recording the findings on photographic film. Samples of blood are also withdrawn from the heart chambers and great vessels. The samples are analyzed for oxygen content.
a. The pressures within the heart indicate any existing strain placed on individual heart chambers. The oxygen content indicates whether the blood is circulating directly through the heart or whether the blood is being shunted because of an anatomical defect.
b. During the entire procedure an electrocardiograph and an electro-tachometer is recording readings on photographic paper. The electro-cardio-tachometer is connected by leads that operate, as do those of the electrocardiograph and instantaneously records the heart rate. It also contains a small light that flashes on with each heartbeat, thus enabling the doctor to observe in the dark the condition of the patient.
c. There are several routes used for the catheter approach to the heart. Not long ago only the right side of the heart was studied by catheterization. The cardiac catheter was inserted by means of a "cut-down" into the antecubital vein of either arm, then manipulated through the innominate vein, superior vena cava, right atrium, tricuspid valve, right ventricle, semilunar valve, and pulmonary artery. The cardiac catheter may also be placed in the right or left femoral vein, then manipulated through the inferior vena cava it may then follow the same path as the catheter entered through
the antecubital vein.
d. Several studies also include the left side of the heart. The approach is made directly to the left atrium by means of an 18-gauge, 6-inch needle with a stylet through the patient's back directly into the heart. After the tip of the needle is placed in the left atrium, the stylet is removed and the catheter is manipulated into the left atrium, left ventricle, and the ascending aorta.
e. Studies now also include the examination of both sides of the heart simultaneously through the transthoracic introduction of two needles, one in each atrium.
f. The patient is taken to the fluoroscopy or cardiology department for the study. The entire procedure may last from 1 to 3 hours. The procedure is a painless one. The patient is prepared as follows:
(1) Solid foods are withheld. Liquids are permitted up to 3 hours prior to the procedure.
(2) Diphenhydramine and Valium may be given 30 minutes prior to the procedure.
(3) A systemic antibiotic may be administered prophylacticly to prevent infection.
(4) After the procedure the patient is returned to his nursing unit, remaining flat in bed for 24 hours or more. The vital signs and insertion site are checked every 10 minutes during the first hour, then every 30 minutes for 3 hours. The patient may be nauseated following the procedure.
