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Wednesday, November 23, 2016

From the SIR Residents and Fellows Section (RFS)

Teaching Topic: Transradial Approach for Noncoronary Interventions: A Single-Center Review of Safety and Feasibility in the First 1,500 Cases

Posham R, Biederman DM, Patel RS, Kim E, Tabori NE, Nowakowski FS, Lookstein RA, Fischman AM. J Vasc Interv Radiol 2016; 27:159-66.

Click Here for Abstract

Transradial access (TRA) is an increasingly common method of performing percutaneous intravascular interventions. Although the interventional cardiology literature has described the benefits of TRA in large prospective studies, the data for TRA in noncoronary interventions is sparse. In this study, a retrospective analysis was performed on 946 patients for 1,531 consecutive procedures using transradial access for noncoronary interventions. Exclusion criteria included sheath sizes >6Fr, Barbeau D waveform, radial artery <2mm, known severe aortic tortuosity, dialysis, and radial artery occlusion. Reported results included success rates of 98.2% with minor and major complication rates of 2.38% and 0.13%, respectively. Endoleak repair and renal/visceral intervention were the only significant predictors of cross over to transfemoral access (TFA). Limitations were stated to be non-randomization of the population, operator proficiency bias, and subclinical complications.

Clinical Pearls

What is the Barbeau classification of pulse waveform and how is it used in selecting eligible patients for TRA?

Radial access is a theoretically feasible approach due to the vascular anatomy of the hand. The hand is supplied by both the ulnar and radial artery. There is collateral flow between arteries via the deep and superficial arches as well as the interosseous collaterals. The Barbeau classification of pulse wave forms is an objective test (adaption of the modified Allen test), which indirectly assess the integrity of the collateral circulation between both arteries. To perform this test, a pulse oximetry device is placed on the thumb and the morphology of a plethysmography tracing is noted. The examiner subsequently occludes the radial artery and observes the waveform over a two minute period (see Figure 1 of article).

· A type A response does not demonstrate a change in the waveform (uninterrupted arterial filling) after occlusion.

· A type B response does not demonstrate interrupted arterial filling, however, there is decreased amplitude of the waveform with adaption and restoration of the previous (unconcluded) waveform by two minutes.

· A type C response demonstrates interrupted arterial filling (cessation of pulsatile waveform) with subsequent delayed appearance of a pulsatile waveform. This is thought to be secondary to recruitment of collaterals.

· A type D response demonstrates interrupted arterial filling, however, there is no restoration of visualized pulsatile collateral flow at two minutes.

What is the standard radial access technique?

Topical nitroglycerine and lidocaine are applied to the wrist 30 minutes prior to cannulation. Preferentially, the left wrist is cannulated. A wrist towel roll is places beneath the wrist to allow for adequate hyperextension. Patient can be positioned prone or supine. Pulse oximeter is applied to the ipsilateral thumb or index finger. After radial access is obtained, a hydrophilic sheath is placed (4-7Fr with preference for smaller sheaths). Catheter lengths of 110 cm with standard 0.035-in access wire are used for engaging the mesenteric vessels. Microcatheters are typically 150 cm. Nonocclusive hemostasis is utilized to decrease risk of radial artery occlusion at the conclusion of the procedure.

Questions to Consider

What are the proposed benefits of TRA versus TFA?

The RIFLE study demonstrated a decrease in access site-related bleeding, net adverse events (in PCI), and decreased length of hospital stays. The RIVAL study, a multicenter prospective randomized controlled trial, showed a decrease in major vascular complications in the TRA arm. TRA also provides for easier hemostasis, the option of earlier ambulation, and increased reported patient satisfaction. Finally, TRA has also been shown in one study to be overall more cost effective.

What complications should be specifically mentioned in the consent process when considering TRA?

Radial artery occlusion (RAO) is a known complication of TRA thought to be secondary to intimal disruption which is reversible and asymptomatic in most subjects. Symptomatic RAO has been reported at 0.2% with digital ischemia being a severe presentation of such. The radial artery is also subject to spasm. The risk of cerebrovascular infection is theoretically increased (although debated) due to proximity to the vertebral artery and necessary aortic arch manipulation. However, this is mediated by preferentially cannulating the left wrist to decrease arch manipulation. Other complications include hematoma, pain, pseudoaneurysm, perforation, and dissection which are also risks of TFA.

Additional References:
Kotowycz MA, Dzavík V. Advances in Interventional Cardiology. Circ Cardiovasc Interv. 2012 Feb 1;5(1):127-33.

Fischman AM, Swinburne NC, Patel RS. A Technical Guide Describing the Use of Transradial Access Technique for Endovascular Interventions. Tech Vasc Interv Radiol. 2015 Jun;18(2):58-65

Post Author:

Lindsay Karr Thornton, MD
SIR RFS Clinical Education Chair
University of Florida

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