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The Radial Artery Access Site for Interventional Neuroradiology Procedures.
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The upper extremity access approach offers great advantages in neurointerventional procedures. The primary advantage is that of ready access to the vertebral artery origin, especially the right vertebral artery that may often be difficult to access from the femoral artery. In the past, however, upper extremity access sites have included the axillary and brachial arteries, which are end arteries without robust collateral networks in case of untoward occlusion. Furthermore, compression of these arteries may be difficult and hematoma formation common, with substantial risk for nerve injury or compartment syndrome. Thus, these access sites have represented sites of "last resort" in most practices. In contradistinction to axillary and brachial artery access sites, the radial artery represents a safe, practical alternative with minimal risk of adverse effects. Unlike the axillary and brachial arteries, the radial artery in most patients contributes to a rich collateral arcade that minimizes or eliminates risk of ischemic complications. This small risk can be further minimized by performing careful evaluation of the patency of the palmar arch by pulse oximetry, Doppler ultrasound, and visual Allen tests. Risk of hematoma formation is minimal, because the radial artery is readily compressed. Hemostasis is readily obtained even in the setting of systemic anticoagulation or multiagent antiplatelet therapy. Indeed, we do not reverse heparinization before sheath removal and simply apply compression banding for 2–3 hours. Although the radial artery is of relatively small size compared with the femoral artery, sheaths up to 6F can be used in most patients. 6 French sheaths are used routinely in cardiac interventions, where the radial artery approach was initially popularized. Thus, most neurointerventional procedures, including aneurysm coiling, intracranial stent placement, and thrombolysis, are readily performed from a radial artery access site. In all cases, we placed a short sheath in the radial artery and then placed guiding catheters through this sheath. We do not recommend the use of long sheaths in the radial artery system. In particular, the use of "guiding sheaths," where the sheath itself is advanced to the target territory as in transfemoral carotid stent placement, has not been done in our practice. Previous authors have applied this technique with resultant radial artery occlusion.11 When possible, we use the radial artery access site for vertebrobasilar interventions not only because of diminished risk of access site bleeding complications but also because of excellent guiding catheter stability afforded by the radial approach. Unlike femoral artery access, where the catheter traverses the large-diameter aortic arch, the guiding catheters with radial artery access are constrained in relatively small-diameter vessels. Thus, herniation of guiding catheters, as commonly seen from the femoral approach, may occur less frequently with radial access cases. We also favor the radial artery access site for thrombolysis cases in the right carotid territory, because the radial access site essentially eradicates bleeding complications even in the face of a systemic thrombolytic state. Use of the radial access site for left carotid thrombolysis remains possible. However, except for anatomy such as a "bovine" arch, such cases can be quite challenging because of difficulty in gaining stable guiding catheter access in the left carotid from the right radial access site. The radial artery access site can also be used for routine diagnostic angiography. Patients may prefer radial access compared with femoral access, because they can sit up immediately after the procedure and can be discharged promptly. The radial access site can also be used in patients receiving warfarin, because hemostasis can be achieved even in the setting of systemic anticoagulation.12 Concern remains regarding the risk of permanent injury to the radial artery, especially with the use of larger sheaths. There is vast literature regarding the risks of radial artery access procedures for coronary indications. This literature has shown the risk of permanent radial artery injury to be low, even after multiple procedures in the same radial artery.13 If careful documentation of patency of the palmar arch is performed, then risk of injury to the hand is minimal even if the radial artery is permanently damaged. Another consideration that should be addressed is whether the patient may need coronary revascularization by using the radial artery as a donor graft. However, these procedures are usually done by using the radial artery in the nondominant arm, which would be the left radial artery in most patients. It would be prudent, however, to discuss use of the radial artery with the referring surgeon to avoid difficulty in the future. Hemostasis at the radial artery access site can be achieved either with manual palpation or a compression device.14 In our practice, if the patient is not anticoagulated, we prefer 10 minutes of manual palpation to achieve hemostasis. If systemic anticoagulation is to be continued or not reversed after the procedure, then we apply a compression device for 2 hours. The various compression devices designed for the radial artery allow for focused compression of the radial artery but avoid compression of the ulnar artery.
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