Vascular Access in Cardiac Catheterization and Intervention Periprocedural Care

Equipment for cardiac catheterization

Various instruments are available for arterial access for cardiac catheterization. The basic components include a needle, wire, and sheath. The specifications of each of these components vary considerably, making it vital to familiarize oneself with characteristics that allow successful access. ^[8]

A tiny skin incision at the site of the needle entry helps prevent damage to the sheath from skin friction and facilitates insertion of the sheath dilator .

The needle varies in length from approximately 2-5 cm and in diameter from 18-21 gauge. The needle bevel should also have a gentle curve so that it allows for easy entry of the wire.

The supplied wires are usually 30-50 cm in length and often have floppy tip and a more rigid shaft. Wires with a straight tip or small angulations are best suited for the radial and brachial artery, as J-tipped wires are often difficult to advance from the sheath into the proximal radial artery.

The most common sheath sizes for radial intervention are 5F-7F. The sheath may be 10 or 21 cm in length. ^{[2, 7]} Some cardiologists prefer the longer sheaths to minimize artery spasms. A sheath with a sidearm is preferable since it permits delivery of heparin and vasodilators. ^{[3, 9, 10]}

Regardless of the artery used, it should ideally be entered during the first needle stick. Repeat attempts induce trauma and spasms. Prior to needle entry, the pulse should be palpated and the site of entry marked. The needle entry site should be about 2 cm proximal to the radial styloid, as this will avoid radial artery bifurcation. ^{[2, 7]}

Lidocaine (1-2%) should be injected superficially around the artery. It may be combined with a tiny amount of nitroglycerin to help promote arterial vasodilatation. Arterial puncture is usually performed with a 21- or 22-gauge needle. Once blood flow is seen in the needle, it should be advanced a few millimeters. The plastic cannula is then advanced over the needle into the artery, and the needle is withdrawn.

Next, a small-caliber wire (0.018 to 0.025-inch diameter) is advanced through the cannula into the artery, and the cannula is removed so that a sheath with a tapered tip can be inserted over the wire. In some cases, the wire may not pass easily into the artery because of abnormal anatomy, vessel tortuosity, or spasm. ^{[2, 7]} Common causes of wire resistance include abnormal anatomy, tortuosity of the vessels, and spasm. If resistance occurs, the wire must be threaded under fluoroscopic guidance.

Catheter selection

The type of any diagnostic or interventional procedure is strongly influenced by the site of arterial access. Specific catheters for left and right radial approaches are available, although femoral or universal catheters can usually be used in the radial approach without difficulty. In some cases, a short JL curve and/or longer JR curve may be needed for procedures performed from the right radial artery.

Some experts indicate that a benefit of the universal catheter for coronary angiography is the ‘‘one-pass’’ technique, which results in less vessel spasm, shorter duration of procedure, less instrumentation, and lower equipment costs. Success rates associated with current universal catheters for diagnostic coronary angiography range from 96%-98%.

The chief disadvantage of the universal catheter is the steep learning curve. Variability in coronary and radial artery anatomy can complicate use of the universal catheter. One may have to utilize certain techniques to successfully use the universal catheters in patients with anatomic abnormalities. In some cases, asking patients to hold their breath can help align the catheter.

Although the small radial artery lumen diameter limits the arterial sheath size (5F-7F), balloons and stents are now available that permit aspiration of thrombus, treatment of lesions at bifurcation and the coronary ostia, and rotational atherectomy. Catheters and guides available for radial artery catheterization include the Castillo curves, Sones catheters, modified venous graft catheters, and internal mammary arterial catheters. A meta-analysis of trials indicated that radial access lowered mortality and improved safety. ^[11]

Accessories

After the procedure in the groin, a heavy pressure dressing is applied. For the wrist, most cardiologists recommend immobilizing the wrist with a splint for the first 24 hours. This helps prevent excessive wrist motion and bleeding. The splint should be worn for the first night, as people tend to move the wrist spontaneously. The splint also helps protect the site of needle puncture.

Like the FemoStop devices (St. Jude Medical Systems, Inc, St Paul, MN) used for the groin, a number of wristbands can be used to obtain hemostasis in the wrist. These 2- to 3-inch–wide bands are applied after the procedure is over and provide firm compression to the puncture site. Once the band is placed, the fingers are assessed for capillary refill and color to ensure that the band is not too tight. The band offers security from external trauma and can be adjusted by the patient. It is worn for the first 12 hours. ^{[2, 7]}

Sheaths

Several sheaths are available for use in the radial/femoral artery. Because of the tendency of the radial artery to spasm when manipulated, longer sheaths are often used. Some of these sheaths are available in a single- or double-dilator setup. The major advantage of the double-dilator setup is the presence of a tapered atraumatic tip, which is less likely to lacerate the artery. However, these sheaths have a transition between the first and second dilator, which can often cause resistance at the skin incision. The single-dilator system with less transition may be more traumatic to the skin and the artery at the insertion site. Several manufacturers are in the process of developing sheaths specific for the radial artery. These newer prototypes include sheaths that can be dilated several sizes and have a porous sheath equipped for administration of antispasm medication. ^[12]

Patients need to fast after midnight, but some laboratories allow the patient to have a light liquid breakfast.

Vital signs are obtained once the patient arrives to the laboratory.

The patient’s entire hand and arm up to the shoulder is prepared and draped in the usual sterile fashion. In addition, one of the groin areas (usually the right groin) should also be prepared and draped in case the radial artery access fails or there is an urgent need for placement of a transvenous pacemaker or an intra-aortic balloon pump. ^[13]

A suitably sized intravenous line should be placed in the contralateral arm, and the blood pressure cuff is usually placed on the leg. If the intravenous line is to be inserted in the same arm as the radial artery cannulation, it needs to be inserted proximal to the wrist or preferably just below the elbow.

The wrist should be slightly hyperextended with a rolled towel underneath the joint for support. A pulse oximeter is placed on the ipsilateral index finger or thumb. Extension tubing can be used between the catheter and the injection manifold so that the operator can move farther from the x-ray source. ^{[2, 7]}

Clothing (other than hospital gown), jewelry, bracelets, and rings should be removed prior to the procedure. These items must be documented and stored securely.

Premedication of the patient

Irrespective of the route of access for cardiac catheterization, the patient must be medically prepared. The procedure must be explained to the patient and an informed consent must be obtained. Most cardiologists do not administer prophylactic antibiotics prior to the procedure. Routine premedication is often used, but some laboratories prefer to administer sedatives during the procedure. The two most commonly used sedatives used include midazolam (1-2 mg IV) and fentanyl (25-50 µg IV every 30-45 minutes).

Medications used for cardiac catheterization are not standardized. Most cardiologists use combinations of medications based on experience. ^{[2, 7]} Some degree of sedation is usually administered irrespective of the access approach. Sedation is required when performing transradial catheterization. The introduction of the dilator and sheath is often painful. Conscious sedation is often the choice of anesthesia, with a dedicated nurse to monitor the patient. Many operators find fentanyl (25-50 µg IV every 30-45 mins) and/or midazolam (0.5-1 mg IV every 30-45 minutes) satisfactory.

Since the radial artery is subject to rather intense spasm, which can be painful to the patient and makes sheath and catheter movement difficult, several drugs may be administered to prevent or relieve the vasospasm. The typical medications used include verapamil, nitroglycerin, lidocaine, adenosine, and papaverine. These medications are administered during sheath insertion and removal or whenever radial spasm is suspected. Most operators routinely wipe the wire with a papaverine-soaked sponge before insertion. Adenosine is a potent vasodilator, but the cost of the medication is a limiting factor.

Anticoagulation is necessary during cardiac angiography via all access routes. Heparin 5,000-10,000 units is administered to prevent thrombus formation. The heparin is rarely reversed at the end of the procedure, primarily because it has a short half-life.

Medications and doses used during cardiac catheterizations are as follows: ^{[2, 7]}

• Nitroglycerin 200 µg/mL (administered via the radial and brachial artery)

• Verapamil 500 µg/mL (administered via the radial artery)

• Lidocaine 2% 20-mg aliquots (administered via the radial artery)

• Papaverine wipe on (radial)

• Heparin 5,000-10,000 units

• Fentanyl 25-50 µg IV prn every 30-45 minutes (transradially, 5 mg IV PRN every 5-15 minutes)

• Midazolam 0.5-2 mg/mL IV prn every 15-30 minutes

Anesthesia

See Premedication of the patient.

Positioning

For both radial and femoral artery catheterization, patients are placed supine. The arms are tucked at the side of the bed for femoral artery access. For radial artery access, the nondominant arm is used and is usually abducted to about 45° to allow for access.

Once the procedure is complete, most cardiologists remove the intra-arterial lines without confirming anticoagulation parameters. Even in patients in whom GPIIb/IIIa inhibitors and/or thrombolytics have been administered, sheaths can be removed and hemostasis obtained with manual compression or a hemostatic device. For both radial and femoral artery access, the hand or feet are assessed for perfusion and capillary refill. In most cases of radial artery cannulation, the patient can ambulate 1-2 hours after sheath removal or whenever the sedation has worn off. Patients who undergo femoral artery access are asked to remain on bedrest for a minimum of 6-8 hours.

After discharge, all patients are asked to avoid excessive use of the involved hand for 24 hours or to refrain from walking until the following morning. Any activity that causes excessive flexion or extension of the wrist/hip is not recommended. The bruising that is common after the procedure usually disappears within 7-10 days. ^{[2, 7]}