Is the Allen's test adequate to safely confirm that a radial artery may be harvested for coronary arterial bypass grafting?

Abstract

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the Allen's test, plethysmography, Doppler ultrasound or MRI imaging was the best method of assessing the presence of adequate collateral blood flow in the arm preoperatively prior to radial artery harvest for conduits during CABG surgery. Altogether 176 papers were identified using the reported search of which 15 represented the best evidence on the topic. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. We conclude that whilst there are theoretical limitations with the Allen's test, for most patients it is an adequate method of assessing collateral arm flow prior to radial artery harvest and several large studies have confirmed the absence of neurological and vascular adverse outcome with a modified Allen's test cut-off point of up to 12 s. However, if there are concerns about collateral flow then a second confirmatory test such as dynamic Doppler ultrasound or measurement of digital pressure changes with radial artery occlusion can also be used prior to harvest. Newer techniques such as Gadolinium-enhanced magnetic resonance angiography have also been described to confirm adequate collateral circulation prior to radial artery harvest for CABG conduit and whilst in time they might come to represent an ultimate 'gold standard' they are clearly too expensive and impracticable for everyday use.

Diameters and Flow Characteristics of Forearm Arteries in the Preoperative Period Using Doppler Ultrasonography in Healthy Individuals

“…In another study, Agrifoglio et al (10) evaluated hand circulation using DUS during RA compression and the removal of the RA was deemed unsuitable for use in CABG surgery. Therefore, avoiding in 5.3% of the patients, other patients undergoing operation had no hand or wrist ischemia in the postoperative period (25). Abu-Omar used DUS in the presence of abnormal AT to evaluate patients undergoing total arterial revascularization.…”

Extensor pollicis longus tendon compression as the etiology of a true aneurysm of the radial artery in the anatomical snuff box

“…10 Radial artery ligation is usually well tolerated, as typified in trauma, 11 distal radial artery ligation for steal syndrome, 12 and radial artery harvest for bypass. 13,14 However, spontaneous or traumatic radial artery thrombosis with acute thumb and finger ischemia has been described with morbid outcomes. [15][16][17] In the setting of RAA with possible suboptimal thumb and second finger perfusion after radial artery ligation, as demonstrated on preoperative imaging, a short-segment vein bypass likely has excellent durability, provides ideal perfusion to the hand, and eliminates the risk of hand or thumb ischemia.…”

Laser speckle contrast analysis for quantifying the Allen test: A feasibility study

“…This could be an indication of an insufficient UA and is already used in the modified Allen test with ultrasound Doppler and pulse‐oximetry. In literature, the cut‐off time of a negative Allen test is not uniform and times of 3–15 seconds are reported . Major hand ischemia is rare, but also minor complications with hand impairment could be troublesome for the patient .…”

“…A negative Allen test suggests an adequate blood supply to the hand by the UA with a closed RA, hence reperfusion within, for example, 5 seconds. The cut‐off times of a negative Allen test vary from 3 to 15 seconds . A positive Allen test suggest an inadequate blood supply by the UA.…”