Cardiac catheterization is usually performed with angiography, a technique of injecting a contrast agent into the vascular system to outline the heart and blood vessels. When a particular heart chamber or blood vessel is singled out for study, the procedure is known as selective angiography. Angiography makes use of cine-angiograms, a series of rapidly changing films on an intensified fluoroscopic screen that record the passage of the contrast agent through the vascular site or sites. The recorded information al-lows for comparison of data over time. Common sites for selec-tive angiography are the aorta, the coronary arteries, and the right and left sides of the heart.
An aortogram is a form of angiography that outlines the lumen of the aorta and the major arteries arising from it. In thoracic aor-tography, a contrast agent is used to study the aortic arch and its major branches. The catheter may be introduced into the aorta using the translumbar or retrograde brachial or femoral artery approach.
In coronary arteriography, the catheter is introduced into the right or left brachial or femoral artery, then passed into the ascending aorta and manipulated into the appropriate coronary artery. Coronary arteriography is used to evaluate the degree of athero-sclerosis and to guide the selection of treatment. It is also used to study suspected congenital anomalies of the coronary arteries.
Right heart catheterization usually precedes left heart catheteri-zation. It involves the passage of a catheter from an antecubital or femoral vein into the right atrium, right ventricle, pulmonary artery, and pulmonary arterioles. Pressures and oxygen satura-tions from each of these areas are obtained and recorded.
Although right heart catheterization is considered a relatively safe procedure, potential complications include cardiac dysrhyth-mias, venous spasm, infection of the insertion site, cardiac perfo-ration, and, rarely, cardiac arrest.
Left heart catheterization is performed to evaluate the patency of the coronary arteries and the function of the left ventricle and the mitral and aortic valves. Potential complications include dys-rhythmias, MI, perforation of the heart or great vessels, and sys-temic embolization. Left heart catheterization is performed by retrograde catheterization of the left ventricle. In this approach, the physician usually inserts the catheter into the right brachial artery or a femoral artery and advances it into the aorta and left ventricle.
After the procedure, the catheter is carefully withdrawn and arterial hemostasis is achieved using manual pressure or other techniques previously described. If the physician performed an arterial or venous cutdown, the site is sutured and a sterile dress-ing is applied.
Nursing responsibilities before cardiac catheterization include the following:
· Instruct the patient to fast, usually for 8 to 12 hours, before the procedure. If catheterization is to be performed as an outpatient procedure, explain that a friend, family member, or other responsible person must transport the patient home.
· Prepare the patient for the expected duration of the proce-dure; indicate that it will involve lying on a hard table for less than 2 hours.
· Reassure the patient that mild sedatives or moderate seda-tion will be given intravenously.
· Prepare the patient to experience certain sensations during the catheterization. Knowing what to expect can help the patient cope with the experience. Explain that an occasional pounding sensation (palpitation) may be felt in the chest because of extrasystoles that almost always occur, particu-larly when the catheter tip touches the myocardium. The patient may be asked to cough and to breathe deeply, espe-cially after the injection of contrast agent. Coughing may help to disrupt a dysrhythmia and to clear the contrast agent from the arteries. Breathing deeply and holding the breath helps to lower the diaphragm for better visualization of heart structures. The injection of a contrast agent into either side of the heart may produce a flushed feeling throughout the body and a sensation similar to the need to void, which sub-sides in 1 minute or less.
· Encourage the patient to express fears and anxieties. Provide teaching and reassurance to reduce apprehension.
Nursing responsibilities after cardiac catheterization may in-clude the following:
· Observe the catheter access site for bleeding or hematoma formation, and assess the peripheral pulses in the affected extremity (dorsalis pedis and posterior tibial pulses in the lower extremity, radial pulse in the upper extremity) every 15 minutes for 1 hour, and then every 1 to 2 hours until the pulses are stable.
· Evaluate temperature and color of the affected extremity and any patient complaints of pain, numbness, or tingling sensations to determine signs of arterial insufficiency. Re-port changes promptly.
· Monitor for dysrhythmias by observing the cardiac moni-tor or by assessing the apical and peripheral pulses for changes in rate and rhythm. A vasovagal reaction, consist-ing of bradycardia, hypotension, and nausea, can be pre-cipitated by a distended bladder or by discomfort during removal of the arterial catheter, especially if a femoral site has been used. Prompt intervention is critical; this in-cludes raising the feet and legs above the head, adminis-tering intravenous fluids, and administering intravenous atropine.
· Inform the patient that if the procedure is performed per-cutaneously through the femoral artery (and without the use of devices such as VasoSeal, Perclose, or Angio-Seal), the patient will remain on bed rest for 2 to 6 hours with the affected leg straight and the head elevated to 30 degrees (Logemann et al., 1999). For comfort, the patient may be turned from side to side with the affected extremity straight. If the cardiologist uses deployed devices, check local nurs-ing care standards, but anticipate that the patient will have less restrictions on elevation of the head of the bed and will be allowed to ambulate in 2 hours or less (Baim et al., 2000). Analgesic medication is administered as prescribed for discomfort.
· Instruct the patient to report chest pain and bleeding or sudden discomfort from the catheter insertion sites immediately.
· Encourage fluids to increase urinary output and flush out the dye.
· Ensure safety by instructing the patient to ask for help when getting out of bed the first time after the procedure, because orthostatic hypotension may occur and the patient may feel dizzy and lightheaded.
For patients being discharged from the hospital on the same day as the procedure, additional instructions are provided. They appear in Chart 26-4.