The aorta and its branches are studied by the injection of a contrast medium
through a plastic catheter or with a needle directly into the aorta. Terms used in
connection with the aortogram are retrograde aortogram (retrograde meaning against
the direction of blood flow) and translumbar aortogram (meaning the injection is made
below the twelfth rib and to the left of the spine). No preparation of the patient is
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Samples of blood are also withdrawn from the heart chambers and great vessels.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
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.