Vascular Access in Cardiac Catheterization and Intervention Technique

Anatomic considerations

Femoral artery

The femoral artery is a continuation of the external iliac artery and is located just below the inguinal ligament. Here, the common femoral artery gives off the superficial femoral and profunda femoral arteries. The femoral artery is usually easily palpable at the groin and widely used for arterial access. When accessed for interventional procedures, the artery should ideally be cannulated below the inguinal ligament so that manual pressure can be applied to obtain hemostasis after the catheters and sheath are removed. Cannulation too proximal complicates manual compression because the artery dives into the pelvic cavity (ie, retroperitoneal space) and is covered by the firm inguinal ligament.

Aortic arch

The aortic arch gives of the right innominate, left common carotid, and the left subclavian arteries. The right innominate artery gives off the right common carotid and then becomes the subclavian artery. The subclavian arteries become the axillary arteries as they pass under the axilla. In the axilla/shoulder, the arteries become the brachial arteries, which then divide just below the elbow into the radial and ulnar arteries. In rare cases, a radial artery may originate from the brachial artery in the upper arm. Thus, when performing a radial artery cannulation, the anatomy should be reviewed before passing any catheters or guidewires. ^{[7, 14]}

Brachial artery

The brachial artery courses down the medial and inner aspects of the upper am. As it approaches the elbow, it becomes slightly superficial and is very close to the median nerve. Distal to the elbow, the brachial artery travels under the supinator and pronator radii teres. At this junction, it divides into the ulnar and radial arteries. ^{[2, 7]}

Radial and ulnar artery

In most patients, the radial artery originates from the brachial artery just below the level of the elbow crease. At this point, it passes laterally along the forearm until it reaches the wrist. In the mid forearm, the artery runs between the flexor carpi radialis and supinator longus tendons. When it reaches the wrist, the radial artery is easily palpated above the trapezium and scaphoid bones and the external lateral ligament.

If cannulation of the artery is attempted too distally, the reticulum will be encountered, and the artery is often branched at this point. It is important, therefore, to attempt cannulation approximately 2-3 cm proximal to the flexion crease of the wrist.

At the level of the hand, the radial artery traverses the space between the metacarpal bones of the thumb and index finger and enters the palm. The vessel then crosses the base of the metacarpal bone of the little finger and joins with the deep communicating branch of the ulnar artery, resulting in a patent deep palmar arch. The superficial palmar arch is made by communication of the ulnar artery with the superficialis branch of the radial artery. ^[15]

The ulnar artery also branches off the brachial artery and passes along the medial aspect of the forearm. At the level of the wrist, it divides into two branches that join the radial artery and its superficial branch to form the deep and superficial palmar arches. Despite good ulnar and radial pulses, an incomplete palmar arch is observed in 10%-20% of patients. ^{[2, 7]}

Any patient with radial artery dominance (ie, an abnormal Allen test result) should not undergo cannulation of that artery. In addition, patients who have ulnar artery dominance tend to have a higher incidence of radial artery access failures with cannulation. ^{[2, 7]}

Ulnar artery

The ulnar artery has rarely been used for cardiac angiography. The ulnar artery is usually smaller, and access can be difficult. Moreover, the position of the ulnar artery at the wrist is inconsistent, and compression for hemostasis is also a problem. ^[16]

Right or left radial artery

The right radial artery is often selected over the left, as it is easier for the operator to perform the procedure. The left radial artery can be used, but, often, the laboratory setup complicates access. Other reasons why one may select one radial artery over the other is the presence of a left internal mammary graft (which is easier to access via the left radial artery) or the possibility of future use of the radial artery as a bypass graft.

In short obese individuals, the aortic arch and descending thoracic aorta are often easier to access from the left radial artery than the right. ^[17] In addition, access to the branches of the aortic arch are also easily accessed from the left radial artery. ^[18]

Femoral artery approach

The percutaneous femoral approach for cardiac catheterization has been widely used and is clearly well established. Unlike the brachial artery approach, the femoral artery approach does not require an arterial cutdown or repair. In addition, the technique can be performed repeatedly in the same patient after a suitable interval. The femoral artery is usually palpable and allows for easy access. The femoral approach is clearly the method of choice in a patient with absent or diminished radial and brachial pulsations, when the brachial or radial approach has been unsuccessful, and when large-caliber catheters are used. ^[19]

The transfemoral route for cardiac catheterization and intervention procedures has stood the test of time and is considered the criterion standard. It has gained universal acceptance because of the following reasons:

• Long history of use and predictably

• Technically easy to access

• Enables use of larger sheaths and other equipment

• Complications are well known

• User experience is extensive

Several closure devices that provide postprocedural hemostasis are available and enable patients undergoing femoral access to ambulate soon after completion of the procedure. Nevertheless, the closure device fails in some cases, resulting in femoral arterial bleeding. Use of collagen-based closure devices often limits access to the groin area for several weeks and even months afterward. ^{[2, 7]}

The following are disadvantages of the femoral approach:

• Prolonged bedrest that may range from 4-8 hours; the larger the sheath, the longer the period of bedrest

• Associated with adverse effects such as urinary retention, femoral nerve neuropathy, and back discomfort

• Vascular complications such as bleeding, femoral artery pseudoaneurysm, and arteriovenous fistula ^{[20, 21]}

• Damage, dissection, or occlusion of the femoral artery

• Cholesterol emboli

Radial artery approach

Transradial cardiac catheterization was first used by Campeau et al in 1989 to perform cardiac catheterizations. ^[14] The technique was successful in most patients, but pulse loss was evident in some patients at the end of the procedure. The first percutaneous transluminal coronary angioplasty (PTCA) performed transradially was done in 1993. Since then, the equipment and procedure have been refined so that radial access is now widely used by cardiologists universally for both diagnostic and therapeutic purposes. ^[8]

Advantages of the radial approach are as follows:

• Dual blood supply to the hand, which minimizes the potential for hand ischemia

• Access for patients with aortoiliac disease or aortic aneurysm

• Does not require prolonged bedrest postprocedure, which is desirable in the patient with congestive heart failure, dyspnea, or back pain

• Easy to compress and achieve hemostasis

• Fewer vascular complications compared with the femoral approach

• Patient preference and acceptability ^[8]

There are some disadvantages to a radial approach, and most of these relate to the small-vessel caliber or tortuosity. The technical difficulties with radial artery access include the following:

• The radial artery is much smaller in diameter (averaging about 2-3 mm) than the femoral artery (5-10 mm)

• Cannulating the radial artery involves a steeper learning curve than the femoral approach

• A smaller sheath and catheter (4F-6F) can be accommodated than in the femoral approach

• Vessel spasm is common

• Guide insertion can be difficult and requires time and patience

• Many cardiologists and radiologists are not completely familiar with the equipment and radial artery anatomy and, thus, are often reluctant to try a new approach

• Increased procedure time and radiation exposure to the patient and cardiologist compared with the femoral approach

A radial artery approach may not be appropriate in all patients. Contraindications include the following:

• Patients with an abnormal Allen test result ^[10]

• Patients who have intra-aortic balloon pump counter pulsation (IABP) are not candidates for radial artery catheterization

• Certain individuals may need larger devices for percutaneous coronary intervention, and the radial artery may not allow for insertion of large sheaths

• Any patient with known Buerger disease, Raynaud disease, collagen vascular disease, or evidence of vascular disease of the upper extremity should not undergo radial artery cannulation

• Certain congenital abnormalities of the radial arteries or subclavian vessels

• Extreme tortuosity or severe atherosclerosis (ie, may preclude safe radial artery cannulation)

• Patients in whom the radial artery may be considered as a conduit for coronary artery bypass grafting or for a dialysis graft ^{[2, 7]}

The transradial approach is rapidly becomig the standard approach in many hospitals. ^[22] This approach has been associated with fewer complications than that with the femoral artery approach, a shorter immobilization period, and a shorter length of hospital stay. Furthermore, a large study showed that the radial artery approach was associated with similar outcomes to those of the femoral approach but with a lower rate of complications—even for complex coronary lesions. ^[23]

Brachial artery approach

The brachial approach is rarely used and usually requires a cutdown. The incision is made just above the crease of the elbow, and the brachial artery and vein are isolated. Brachial arterial access is a viable option in patients who have iliac or femoral arterial disease. The technique is also suitable in very obese patients in whom the groin approach may be difficult for obvious reasons. ^[10] Another advantage occasionally cited for the direct brachial approach is use of a single catheter (Sones catheter) for left heart and coronary artery catheterization.

The brachial artery cannot be used more than 2-3 times for cardiac catheterization. Rarely, the brachial artery approach may limit blood flow to the hand, necessitating immediate removal of the catheter

Radiation exposure

Radiation exposure is unavoidable regardless of the access route selected. There is evidence that using the radial artery to perform coronary interventions often results in more radiation exposure than the femoral artery approach, and this is greater when using the right arm than the left. Radiation exposure generally decreases as operator experience increases.

Other considerations

Difficult guidewire entry

After successful arterial access is achieved with the needle, it is sometimes difficult to advance the guidewire. This may be related to the following:

• Tortuosity

• Vessel spasm

• Radial artery stenosis or occlusion

• Guidewire may be in a side branch

• Abnormal radial artery takeoff from brachial artery

• Wire abutting the wall

In such scenarios, the following may be attempted:

• The use of fluoroscopy for guidance

• Rotation of the needle to change bevel angle

• Use a smaller diameter hydrophilic wire

• Administer a vasodilators intra-arterially through the needle and then attempt to advance the wire

Difficulty removing sheath

This is rare but can occur in small patients, especially women, and often results from intense spasm. If this occurs, the following may be tried:

• Administer vasodilators prior to removal

• Administer pain medication

• Gently rotate the sheath during removal while applying distal skin traction

Sheath removal

Sheath removal is not a problem from the femoral artery. However, the sheath should not be removed from the radial artery without preparation. In many cases, when the sheath is removed, the radial artery goes into spasm. Thus, vasodilators, lidocaine, and sedatives should be available.

Hemostasis

Prior to the availability of hemostatic devices, the cardiologist or nurse had to apply manual pressure to the groin for 30-45 minutes to obtain hemostasis postprocedure. ^{[2, 7]} Now, there are several methods of obtaining hemostasis at the catheter insertion site. The choice of method to obtain hemostasis is strictly personal preference of the cardiologist.

Difficulties of transradial intervention

Unlike the femoral artery, which is large and easily palpated, the radial artery is small, and the pulsations are not strong. The first needle stick is done with care because a miss usually results in vessel spasm. In such cases, there are several options, as follows:

• Delay the procedure for 2-30 minutes to allow the spasm to resolve

• Attempt cannulation at a proximal site

• Administer nitroglycerin (sublingually, intravenously, or topically on the hand)

• Ask the patient to open and close hands for a few minutes

• Use the brachial artery, contralateral radial artery, or femoral artery

In some cases, an adequate radial pulse may be palpated, but there is no return of blood in the needle lumen upon entry into the vessel. In such scenarios, the physician needs to consider the possibility of disease of the radial artery or that the pulse is due to the ulnar blood flow.

In some cases, the radial artery may be very mobile and may shift during needle entry. In these cases, the artery may have to be stabilized between the fingers while trying to cannulate it with a needle. ^{[2, 7]}