Transradial cardiac catheterization: Exploration of the new standard of care

by Nader Elgharib, MD, and Cameron Donaldson, MD

After more than 20 years of experience with transradial cardiac catheterization, there are now multiple registry and trial data to recommend the radial approach as part of the standard of care for diagnostic coronary angiography and percutaneous coronary intervention.

Potential advantages for this approach compared with the transfemoral approach include reduction in bleeding complications, peri-procedural stroke and combined in-hospital death and MI, as well as improved patient satisfaction. The recent multicenter randomized RIVAL trial demonstrated a mortality benefit for STEMI patients undergoing radial PCI, highlighting the strengths of this approach in high-risk acute coronary syndrome when multiple antiplatelet and antithrombotic agents are used and where the risk of bleeding complications is higher.

	Nader Elgharib

Two instances where femoral access is preferred are known upper extremity arterial anatomical variation and poor collateral circulation in the hand. Approximately 10% to 15% of patients have anatomical variants, with half of these being represented by a high bifurcation of the radial artery. These vessels branch off of the axillary or brachial arteries and are frequently small and tortuous, making them prone to spasm and sometimes difficult to traverse, even with a hydrophilic guidewire. If the patient has a dilated aortic root, carefully timed deep inspiration may be required to realign the innominate artery with the ascending aorta. Radial loops, excessive subclavian or innominate tortuosity and retroesophageal aorta (present in one in 400 patients) can prevent selective coronary engagement, even in the hands of an experienced operator. When one of these abnormalities is suspected (mostly in older patients), contralateral radial artery access could be attempted, as most anatomic variants are unilateral.

Most catheterization suites provide optimal operator comfort and minimal radiation exposure via the right radial approach. Some operators report lower fluoroscopy time and radiation dose in older patients from the left radial approach. Use of the left radial is preferred if visualization of the left internal mesenteric artery (LIMA) is desired.

	Cameron Donaldson

The most common reason for choosing a priori to obtain access via the femoral artery is failure to demonstrate adequate collateral perfusion in the hand. This is best determined using the modified Allen’s test with pulse oximetry and plethysmography. This method is more sensitive than the modified Allen’s test and resulted in only 1.5% of screened patients being excluded from a transradial procedure.

Procedural aspects

There are a number of notable differences between transradial and transfemoral catheterization techniques, mostly stemming from the fact that the radial artery is smaller (typically 2.5-mm to 3-mm diameter) and upper extremity anatomy more tortuous and variable.

The radial artery is accessed 1-cm to 2-cm proximal to the styloid process using the modified Seldinger technique (single or double wall stick). A highly tapered, 5 French hydrophilic sheath is used to minimize intravascular trauma. A premade cocktail of 40 U/kg of heparin, 200 mcg of nitroglycerin and 2.5 mg of verapamil is injected through the sheath to reduce the chances of thrombosis or spasm. Diluting the cocktail with blood withdrawn from the sidearm to fill a 10-cc cocktail syringe minimizes discomfort associated with injection.

Catheters should be advanced under fluoroscopy over a guidewire to avoid vessel trauma and prolapse into the right common carotid. Rarely, for patients more than six feet tall, longer (.110 cm) catheters may be necessary to reach the coronary ostia. The standard catheters shaped for access via the femoral artery can be used in the transradial approach, with downsizing from JL4 to JL3.5. To minimize catheter exchanges, there are a variety of specialized transradial catheters available to engage both the left and right coronaries. For graft visualization from the left radial approach, LIMA and AL1 catheters are the first choice for arterial and venous grafts, respectively.

When planning transradial PCI, standard guide catheters (EBU, AL or XB guide catheters) generally provide adequate support for LAD or circumflex interventions. For right coronary artery interventions, AL 0.75 or higher are useful if additional support is needed. If complex or multivessel PCI is anticipated, upsizing to a 6 or 7 French sheath may be prudent. Operators have also used sheathless guide catheters up to 8 French.

Figure 1. Culotte stenting of the left anterior descending artery and first diagonal branch from the right radial approach. Images: Nader Elgharib, MD

Currently, experienced operators can perform most complex coronary interventions via radial access, going as far as retrograde chronic total occlusion recanalization using bilateral radial or combined radial and femoral access. We have successfully performed peripheral angiograms and renal and iliac interventions via the transradial approach.

At the end of the procedure, use of one of the many available hemostatic devices is recommended. They provide rapid hemostasis and less post-procedure monitoring time without hindering venous drainage or compressing the ulnar artery. The minimal degree of compression necessary to produce hemostasis should be used to allow some antegrade flow and reduce the risk of radial occlusion.

Complications and management

In the RIVAL trial, centers in the highest tertile of radial volume had better outcomes, underscoring the great potential of the transradial approach. The high “skill cap” of this delicate technique is driven by a significant learning curve and familiarity with myriad complications, many of which are unique to radial procedures.

Forearm hematoma may develop shortly after removal of the compression device and occurs relatively rarely (1.2% of the radial group in RIVAL). The risk of developing a hematoma can be minimized by deliberate advancement of the guidewire, stopping with any resistance and injecting contrast through the side port of the sheath to detect perforation or anatomical barrier. Small- or moderate-sized perforations can be crossed using a 0.014-inch wire, with placement of a diagnostic or guide catheter over the breached segment, providing hemostasis.

General treatment for hematoma includes analgesia, local ice and use of an additional bracelet. Forearm diameters should be measured regularly and if expansion is noted despite these initial steps, a blood pressure cuff can be inflated over the hematoma. Finger oxygen saturation should be monitored during cuff inflation. If there is extension above the elbow, suspect muscular infiltration and threatening limb ischemia. At this point, surgical evacuation may be necessary to avoid compartment syndrome. This complication is, however, rarely seen if the patient is monitored and managed appropriately.

Figure 2. Stenosis of the proximal vein graft to the first marginal branch of the left circumflex artery. This area was stented from the left radial approach.

Other possible complications include occlusion, avulsion or pseudoaneurysm of the radial artery. Radial artery thrombotic occlusion is common (10.5% in one series of 488 patients), but often asymptomatic, and although patency rates are markedly improved after a 4-week course of low molecular-weight heparin, the presence of adequate collateral perfusion eliminates the need for anticoagulation. Avulsion is a rare but catastrophic complication and can be avoided by careful sheath retrieval at the end of the case, treating any evidence of spasm with intra-arterial vasodilators and, if necessary in extreme cases, papaverine or an axillary nerve block. Pseudoaneurysm is an extremely rare late complication of radial catheterization and should be suspected in any patient presenting days to weeks post-procedure with increasing pain, pulsatile mass or swelling over the site.

Conclusion

Transradial catheterization is expanding in the United States, supported by encouraging evidence from multicenter randomized trials. Going forward, this technique will serve as an important tool in every cath lab operator’s armamentarium. We believe that proficiency in transradial access should be a standard component of interventional cardiology training.

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Cameron Donaldson, MD, is a cardiology fellow at the University of Vermont College of Medicine, Burlington, Vt.; Nader Elgharib, MD, is an assistant professor of medicine at the University of Vermont and an interventional cardiologist at the affiliated hospital Fletcher Allen Health Care.

Disclosure: Dr. Donaldson reports no relevant financial disclosures; Dr. Elgharib is a consultant for Terumo Corporation.