Cardiac Catheterization Laboratory: Diagnostic and Therapeutic Procedures in the Adult Patient

Indications for Cardiac Catheterization in the Adult Patient

Box 2.1 lists indications for cardiac catheterization. The major indication is for the detection of coronary artery disease (CAD); the remaining indications are focused on hemodynamic assessment to evaluate valvular heart disease, pulmonary hypertension, and cardiomyopathies. With respect to CAD, approximately 20% of the adult population studied will be found to have normal coronary arteries. Despite continued improvements in noninvasive assessment, coronary angiography is currently considered the gold standard for diagnosing and defining the extent of CAD. With advances in MRI and multislice CT scanning, the next decade may well see a further evolution of the CCL to an interventional suite with fewer diagnostic responsibilities.

Box 2.1

Indications for Diagnostic Catheterization in the Adult Patient

Coronary Artery Disease

Symptoms

• Unstable angina

• Postinfarction angina

• Angina refractory to medications

• Typical chest pain with negative diagnostic testing

• Family history of sudden death

Diagnostic Testing

• Strongly positive exercise tolerance test

• Early positive, ischemia in ≥5 leads, hypotension, ischemia present for ≥6 min of recovery

• Positive exercise testing after myocardial infarction

• Strongly positive nuclear myocardial perfusion test

• Increased lung uptake or ventricular dilation after stress

• Large single or multiple areas of ischemic myocardium

• Strongly positive stress echocardiographic study

• Decrease in overall ejection fraction or ventricular dilation with stress

• Large single area or multiple or large areas of new wall motion abnormalities

Valvular Disease

Symptoms

• Aortic stenosis with syncope, chest pain, or congestive heart failure

• Aortic insufficiency with progressive heart failure

• Mitral insufficiency or stenosis with progressive congestive heart failure symptoms

• Acute orthopnea/pulmonary edema after infarction with suspected acute mitral insufficiency

Diagnostic Testing

• Progressive resting left ventricular dysfunction with regurgitant lesion

• Decreasing left ventricular function and/or chamber dilation with exercise

Adult Congenital Heart Disease

Atrial Septal Defect

• Age >50 years with evidence of coronary artery disease

• Septum primum or sinus venosus defect

Ventricular Septal Defect

• Catheterization for definition of coronary anatomy

• Coarctation of the aorta

• Detection of collaterals

• Coronary arteriography if increased age and/or risk factors are present

Other

Acute myocardial infarction therapy—consider primary percutaneous coronary intervention

• Mechanical complication after infarction

• Malignant cardiac arrhythmias

• Cardiac transplantation

• Pretransplantation donor evaluation

• Posttransplantation annual coronary artery graft rejection evaluation

• Unexplained congestive heart failure

• Research studies with institutional review board review and patient consent

Patient Evaluation Before Cardiac Catheterization

Diagnostic cardiac catheterization in the 21st century is universally considered an outpatient procedure except for the high-risk patient. Therefore the precatheterization evaluation is essential for quality patient care. Evaluation before cardiac catheterization includes diagnostic tests that are necessary to identify high-risk patients. An electrocardiogram (ECG) must be obtained for all patients shortly before catheterization. Necessary laboratory studies before catheterization include an appropriate coagulation profile (prothrombin time [PT], partial thromboplastin time [PTT], and platelet count), hemoglobin, and hematocrit. Electrolytes are obtained together with baseline blood urea nitrogen and creatinine (Cr) values to assess renal function. Recent guidelines express a preference for estimation of the glomerular filtration rate (GFR) using accepted formulas, and many clinical laboratories now report this value routinely. Urinalysis and chest radiography may provide useful information but are no longer routinely obtained by all operators. Prior catheterization reports should be available. If the patient had prior PCI or coronary artery bypass graft (CABG) surgery, anatomic information concerning stent or bypass placement also must be available.

Patient medications may need to be altered in preparation for a heart catheterization. On the morning of the catheterization, antianginal and antihypertensive medications are routinely continued, whereas diuretic therapy is withheld. Patients with diabetes are scheduled early, if possible, because the procedure requires nil per os (NPO) status. No short-acting insulin is given, and half of the long-acting insulin dose is usually administered. Patients on oral anticoagulation should stop warfarin (Coumadin) for 48 to 72 hours before catheterization to target an international normalized ratio (INR) of 1.8 or less if femoral artery access is used. Radial artery access is considered an option without discontinuation of warfarin. For patients who are managed with non–vitamin K antagonist novel oral anticoagulant (NOAC) therapy, the dose may need to be withheld for 24 to 48 hours depending on renal function and the bleeding risk of the procedure. In patients who are anticoagulated because of mechanical prosthetic valves, the best management may be intravenous (IV) heparin before and after the procedure, when the warfarin effect is not therapeutic. IV heparin is routinely discontinued 1 to 2 hours before catheterization, except in patients with unstable angina. Therapy with aspirin or P2Y12 platelet inhibitors or both is almost always continued for patients with angina or those with prior CABG.

Patient Monitoring and Sedation

Standard limb leads with one chest lead are used for ECG monitoring during cardiac catheterization. One inferior and one anterior ECG lead are monitored during diagnostic catheterization. During an interventional procedure, two ECG leads are monitored in the same coronary artery distribution as the vessel undergoing PCI. Radiolucent ECG leads permit monitoring without interfering with angiographic data.

Sedation in the CCL, from preprocedural administration or from IV administration during the procedure, may lead to hypoventilation and hypoxemia. The administration of midazolam, 1 to 5 mg intravenously, with fentanyl, 25 to 100 µg, is common practice. Institutional guidelines for conscious sedation typically govern these practices. Light to moderate sedation is beneficial to the patient, particularly for angiographic imaging and interventional procedures. Sedation is critical for patients who undergo a radial artery approach; conscious sedation has been shown to reduce the incidence of radial artery spasm, which, when severe, may force the operator to adopt a transfemoral approach to complete the procedure. Deep sedation, in addition to its widely recognized potential to cause respiratory difficulties, poses distinct problems in the CCL. Deep sedation often requires supplemental oxygen, which complicates the interpretation of oximetry data and may alter hemodynamics.

More complex interventions have resulted in longer procedures. Although hospitals require conscious sedation policies, individual variation in the type and degree of sedation is common. General anesthesia is rarely required for coronary procedures, but it is frequently used for percutaneous valve procedures. Advancements in intracardiac echocardiography have decreased the need for intubation and transesophageal echocardiography (TEE) in certain patients and procedures. Pediatric procedures require general anesthesia more commonly than those in adults. As the frequency of noncoronary procedures increases, the presence of an anesthesiologist in the CCL will be required more often.

Left-Sided Heart Catheterization