Vasodilators and Radial Artery Occlusion

adial artery occlusion remains the Achilles heel of the transradial approach to arterial catheterization.Granted, radial artery occlusion is usually asymptomatic, not associated with hand ischemia, and resolves in a majority of cases by 30 days after the procedure, but in those patients, who persist with chronic radial occlusion, the future potential for radial artery reuse as a route for catheterization, dialysis shunt, or as an arterial graft for surgical bypass is forever lost.Early radial operators were pleased to have developed an approach that reduced bleeding and enhanced the experience for the patient.Radial artery occlusion was occasionally noted but remained asymptomatic and appeared to be an unavoidable tradeoff for this novel approach that otherwise was an advancement over the classical femoral approach.With further experience with transradial procedures, it became apparent that radial occlusion was not an inevitable downside of transradial access but rather a potentially modifiable outcome.Adequate anticoagulation for every transradial procedure whether diagnostic or interventional was perhaps the first lesson in risk modification.Unlike the legacy femoral approach that appeared safe when done without anticoagulation at least for diagnostic procedures, radial artery occlusion could be reduced by a factor of 16 from 71% to 4.5% with the simple addition of 5000-U heparin. 1 Radial arteries, in general, have an average diameter on the same order as a 6F sheath.This results in a snug arterial fit for the vascular sheath, setting up an environment of reduced blood flow and endothelial damage from the physical trauma of catheter contact.This milieu of damaged endothelium, a localized puncture wound to the arterial wall, and sluggish blood flow from subsequent hemostatic compression is a perfect set up for thrombosis.The use of heparin attenuates this prothrombotic environment while hemostasis is obtained and reduces the risk of radial occlusion.2 Hemostasis with techniques of patent hemostasis balance the external pressure exerted to prevent bleeding against the internal lumen blood pressure.The technique maintains antegrade radial artery flow through the region of arterial injury during hemostasis and can further reduce the incidence of radial artery occlusion to <1%. 3 Despite successes in reducing radial artery occlusion, not all operators have been able to replicate the success of some hemostasis experts, and room for further innovations to minimize this complication remains.One attempt to reduced occlusion at hemostasis was recently demonstrated by our group 4 in a multicenter trial in which the simple addition of a bolus of 500 µg of intraarterial nitroglycerin before sheath removal resulted in a significant reduction in radial artery occlusion over placebo.Was it the NO donor property of nitroglycerin that improved the results with vasodilation enhancing flow through the region of hemostasis