Although the adoption of radial coronary angiography and radial PCI in the United States lags behind that of other countries, particularly those in Europe and Asia, transradial coronary intervention has seen an 8% to 10% increased utilization in the U.S., a trend that is expected to continue. The Society for Cardiovascular Angiography and Interventions (SCAI) published an executive summary on transradial access (TRA) for coronary and peripheral procedures in the November 2011 issue of Catheterization and Cardiovascular Interventions. The overview examined utility, utilization, and training aspects to consider when performing angioplasty via the radial artery.
“Historically, the traditional route to access blocked coronary arteries has been through the larger femoral artery,” says Ronald P. Caputo, MD, FACC, FSCAI, lead author of the SCAI paper. “TRA is advantageous to transfemoral access because it’s less invasive and has been shown to decrease the risk of access site complications and bleeding.” TRA also is preferred by the vast majority of patients because, unlike the transfemoral approach, it causes less discomfort and allows them to stand up and ambulate immediately following the procedure. In addition, some patients undergoing TRA procedures can be discharged the same day. “These advantages ultimately can decrease length of stay and reduce hospitalization costs while still improving clinical outcomes,” adds Dr. Caputo.
Avoiding Complications in Transradial Access
Appropriate patient selection for TRA is the first important step in a successful procedure, says Dr. Caputo. Ideal patients for TRA include those with a palpably large radial artery with a strong pulse and a normal Allen’s test with no history of an ipsilateral brachial procedure. Contraindications include abnormal Allen’s test, a severe vasospastic condition (eg, Raynaud’s), a planned or present arteriovenous shunt for dialysis, and absence of a radial pulse. Future use of the radial artery for an arterial conduit for bypass may also be a relative contraindication.
While appropriate patient selection helps avoid complications of TRA for coronary interventions, Dr. Caputo says it is important to note that the radial artery can be damaged by puncture, sheath insertion, and catheter manipulation, as with any artery. Vascular complications specific to TRA include spasm, compartment syndrome, and radial artery occlusion (RAO; Table 1).
The SCAI executive summary suggests that generous patient sedation, spasmolytic cocktails, and hydrophilic sheaths of the smallest possible diameter can be used as possible methods for preventing spasms. Routine heparin therapy to reduce risk of RAO is also suggested in the SCAI paper. “When they occur, hematomas tend to be small and controlled well with manual pressure,” adds Dr. Caputo. “As soon as local bleeding is suspected, severe complications can be limited by discontinuing IV anticoagulant therapy, controlling pain and blood pressure, and using a blood pressure cuff for compression.” The most serious complication is compartment syndrome, which is rare but must be considered.
Optimizing Training in Transradial Access
“Optimal training in TRA is recommended because there are nuances to consider when navigating smaller arteries,” Dr. Caputo says. “Unfortunately, the number of invasive and interventional cardiologists who can adequately train others remains low, and guidelines on TRA training programs are vague.” Currently, most training is acquired at 1- to 2-day programs that consist of formal, in-person interactive teaching and proctorship, and/or informal, didactic lectures, readings, instructional videos, and simulations. “Clinicians can also gain training by visiting the practices of those who have expertise in TRA and shadowing them for a day or two,” adds Dr. Caputo. The objectives of TRA training include the acquisition of knowledge and competence in several areas (Table 2). The learning curve for TRA tends to be longer than that associated with transfemoral approaches, and no standard definitions or guidelines exist for competency. The SCAI proposes the following levels of competency:
Level 1 competency: Able to perform simple diagnostic cases on patients with favorable upper limb anatomy (eg, larger men).
Level 2 competency: Able to perform simple diagnostic and interventional procedures on patients with more challenging upper limb anatomy (eg, elective single vessel PCI or bypass grafts, smaller women, and radial and subclavian loops).
Level 3 competency: Able to perform complex interventional procedures even with challenging limb anatomy (eg, chronic total occlusions, multivessel PCI, and acute myocardial infarction).
Advancing Technology for Transradial Access
As more TRA procedures are completed successfully and patient and physician interest grows, so too will advancements in the technology, says Dr. Caputo. “The development of smaller catheters specifically meant for TRA will be beneficial for physicians in the future. As adoption of TRA procedures continues to increase, it’s important that guidelines on training and competency are created to ensure the safest and most effective outcomes.”
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