Vascular Access in Cardiac Catheterization and Intervention

Cardiac catheterization is performed for both therapeutic and diagnostic reasons. ^{[1, 2]} Like any invasive procedure, cardiac catheterization is associated with complications, so the decision to undertake the procedure should be based on the risks and benefits.

More than a million cardiac catheterizations are performed each year in the United States. Several approaches to cardiac catheterization have been developed over the past 40 years. The three most widely used techniques for cardiac catheterization involve access through the femoral, radial, or brachial artery, with access to the brachial artery usually obtained by a cutdown approach and the others via a percutaneous approach.

Traditionally, the heart has been accessed via the femoral artery; however, in the last decade, the radial artery has been more widely used, since it (1) is readily accessible (even in obese individuals), (2) is the preferred site of access by many patients, (3) is associated with a lower incidence of hemorrhage, and (4) allows earlier ambulation of the patient following the procedure than a femoral catheterization. Since the radial artery is of a smaller caliber than the femoral artery, the radial artery cannot accommodate large-size catheters, spasms in some cases (thereby preventing catheter passage), and occludes in 5%-10% of patients postprocedure, although this seldom causes symptoms.

Indications for cardiac catheterization include the following:

• To confirm the presence of suspected coronary artery disease (CAD) and define its anatomical location and severity

• To perform angioplasty or stenting in a patient with symptoms of CAD

• To determine the presence and severity of valvular heart disease

• To assess the presence of CAD in patients who are referred for cardiac surgery so that concomitant bypass surgery can be performed, if indicated

• To provide anatomic and hemodynamic information on the various heart chambers and great vessels

• To assess the presence of pulmonary embolism and/or efficacy of treatment with thrombolytic therapy

• To help confirm angiographic and hemodynamics before initiating therapy in patients with suspected hypertrophic cardiomyopathy

• To provide details about potential responsiveness of the vessel to vasodilators in patients with pulmonary hypertension

• To assess the presence of CAD in patients with chest pain of uncertain origin in whom there is confusion about the presence of CAD (ie, who are unable to undergo noninvasive testing or who have indeterminate nondiagnostic stress test results)

Over the years, the technique of cardiac catheterization has greatly improved and is usually tolerated by patients with acute myocardial infarction, ventricular tachycardia, or cardiogenic shock. Currently, the only absolute contraindication to cardiac catheterization is the inability of the patient to provide consent.

Relative contraindications include the following:

• Severe uncontrolled hypertension and/or pulmonary edema; these should be controlled prior to the procedure

• Decompensated left-sided heart failure

• Severe ventricular irritability that may complicate interpretation of left-sided heart catheterization

• Reversible anemia, which should be corrected with blood transfusions

• Hypokalemia

• Digitalis toxicity

• Allergy to contrast dye

• Acute or ongoing renal failure, without dialysis

• Bleeding disorder, including warfarin therapy

Procedure Planning

It is important to select the right patient for radial artery intervention. Ideal features for good outcome include the following features:

• Hemodynamically stable patient

• Preferably younger than 70 years

• No prior history of radial or brachial artery intervention

• Palpable radial artery with a strong pulse

• Normal Allen test result

Complication Prevention

Complications tend to be more common in patients with anatomical abnormalities. Complications associated with radial artery access do occur but are far more tolerated and milder than those associated with femoral access. ^{[3, 4, 5]}

Spasm is the most common complication of radial artery cannulation and may be reduced by administering ample patient sedation, using smaller-caliber sheaths, and using antispasmodic medications. Wiping the catheters with verapamil or papaverine may help prevent arterial spasm. If spasm of the vessel occurs, adequate time should be given for it to relax in order to avoid perforation of the vessel. ^[6]

Hematoma can occur with arterial access. Most cases can be prevented by firm digital pressure after sheath removal. In rare cases, with radial catheterization, the hematoma may occur in the axilla or neck area after wire perforation of the vessel.

Compartment syndrome can be limb-threatening but is very rare. This complication is best avoided by preventing it, which may include adequate control of pain, discontinuation of thrombolytics when not needed, use of external compression, and close monitoring of the extremity. Upon any evidence of compartment syndrome, a vascular consult should be obtained immediately. ^{[2, 7]}

Radial artery occlusion is not a concern if the ulnar artery is patent. However, if the palmar arch is not patent, heparin therapy may be administered to assist in reestablishing blood flow. Risk factors for radial/femoral artery occlusion include the following:

• Small artery/large catheter mismatch

• Female sex

• Lack of heparin use

• Diabetes

• Prolonged artery compression due to bleeding

Artery dissection and perforation often occur when the wire is advanced despite resistance. To prevent this complication, the wire should be advanced under fluoroscopy and discontinued upon any resistance. Dissections and perforations are easily diagnosed during angiography. If small, most will close spontaneously. In rare cases, a covered stent may be placed across the perforation.

Pseudoaneurysms of the femoral and radial artery have been reported but are rare. Most can be controlled by applying local pressure. In some cases, these pseudoaneurysms may enlarge, and a vascular surgical consult may be required.

Late bleeding at the catheter site occurs in occasional cases. Hence, at discharge, all patients are instructed to observe their hand/groin for the following 24 hours. If bleeding occurs, the patient should apply digital pressure for at least 30-45 minutes. If this persists, the patient may need to return to the emergency room for better assessment of the site. In most cases, the bleeding is minor. In general, bleeding at the radial site is better tolerated than that seen in the groin. ^{[2, 7]}

Procedural failure results from an inability to gain artery access or to successfully visualize the coronary vessels. The latter may be due to anatomic variations or tortuosity in the radial, brachial, or subclavian vessels. Procedural failure generally lessens with experience but still occurs in about 5% of cases.

Certain types of hydrophilic-coated sheaths have been reported to cause granulomatous reactions at the site of needle entry. ^{[2, 7]}

Vascular complications of catheterization

These may include the following:

• Accelerated atherosclerosis

• Arteriovenous fistula

• Avulsion of artery

• Bleeding

• Compartment syndrome

• Cutaneous infection

• Delayed reflex sympathetic dystrophy

• Digital ischemia

• Hematoma

• Perforation, laceration, dissection

• Pseudoaneurysm

• Vessel spasm

• Subcutaneous granulomatous reaction (hydrophilic coating)

• Subacute and delayed occlusion

• Transient vocal cord paralysis