Cardiac catheterization is an invasive technique that is used as a clinical tool for assessing the anatomy and physiology of the heart and its associated vasculature. It is performed by passing a small catheter through a peripheral artery or vein, under local anesthesia, into the right and/or left side of the heart. Right-heart catheterization was once a routine part of each cardiac catheterization. However, because this adds little information to the workup of a patient with coronary artery disease (CAD), it is now performed in fewer than 25% of procedures.1 Left-heart catheterization with coronary angiography is the gold standard for determining the presence of significant CAD. Heart catheterizations can be both diagnostic and therapeutic.
PERFORMING THE CATHETERIZATION
Cardiac catheterization is performed with local anesthesia administered at the catheter placement site. Mild sedation, with IV midazolam, lorazepam (Ativan, generics), or diphenhydramine (Benadryl, generics), is used frequently. IV fentanyl (Sublimaze, generics) or morphine can be used for additional pain relief.2
More than 95% of catheterizations are done using a femoral approach, in which a needle puncture is made in the femoral artery (left-heart catheterization) or the femoral vein (rightheart catheterization).
CLINICAL USES
The tips of the catheters are used to measure cardiac pressures or to inject radiographic contrast agents. Right-heart catheterization is useful for significant left and/or right ventricular dysfunction, valvular disease, myopericardial disease, or suspected intracardiac shunting; and it remains the gold standard for diagnosing pulmonary hypertension.3 Left-heart catheterization is most commonly used for assessing coronary artery anatomy and defining the presence and degree of atherosclerosis (see Table: Indications and contraindications for heart catheterization). The findings of diagnostic catheterizations characterize the extent and severity of cardiac disease and help determine the most appropriate medical, surgical, or catheter-based treatment.
PATIENT PREPARATION
Before the procedure, the cardiologist performing the catheterization should fully explain the associated benefits and risks to the patient and obtain written informed consent. A precatheterization assessment should include a detailed history and physical examination, CBC, basic metabolic panel, coagulation studies if indicated, chest radiography, and ECG.
The patient should fast for 8 hours before the procedure. Certain medications such as warfarin (Coumadin, Jantoven, generics) and metformin should be withheld. Other medications may be held at the discretion of the referring clinician. Appropriate therapies may be necessary to minimize intraprocedure and postprocedure risk. Pretreatment with aspirin, 325 mg orally, may be given if coronary intervention is likely; and clopidogrel (Plavix), 300 mg loading dose, may be given if there is a strong possibility of stenting.3 Premedication with oral prednisone or IV hydrocortisone (A-Hydrocort, Solu-Cortef), cimetidine, and diphenhydramine may be necessary if the potential for a dye allergy exists. In addition, adequate IV hydration should be employed in all patients in order to avert the risk of contrast-induced nephropathy from the contrast load.
BOTTOM LINE
Left-heart catheterization is a crucial part of diagnostic cardiology. Right-heart catheterization may be helpful in selected patients. In spite of the availability of other imaging modalities, coronary angiography remains the clinical gold standard for determining the presence of significant CAD. Heart catheterization is an invasive procedure with inherent risks, so it is important to weigh the benefits and risks of the procedure with the patient before proceeding. JAAPA
Nicole Hatcher is a PA in the Cardiac Assessment, Recovery, and Evaluation (CARE) unit, Sentara Heart Hospital, Norfolk, Virginia. The author has indicated no relationships to disclose relating to the content of this article.
Mary Hewett, MS, PA-C, department editor
REFERENCES
1. Kasper D, Fauci A, Longo D, et al, eds. Harrison's Principles of Internal Medicine. 16th ed. New York, NY: McGraw-Hill; 2005.
2. Griffin B, Topol E. Manual of Cardiovascular Medicine. 3rd ed. Philadelphia, PA: Lippincott; 2004.
3. Mehta S, Yusuf S, Peters R, et al. Effects of pretreatment with clopidogrel and aspirin followed by long-term therapy in patients undergoing percutaneous coronary intervention: The PCI-CURE Study. Lancet. 2001;358(9281):527-533.
4. Scanlon P, Faxon D, Audet A, et al. ACC/AHA guidelines for coronary angiography: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Angiography) developed in collaboration with the Society of Cardiac Angiography and Interventions. J Am Coll Cardiol. 1999;33(6):1756-1824. http://content.onlinejacc.org/cgi/content/full/33/6/1756. Accessed December 7, 2009.
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