Noninvasive evaluation of hand circulation before radial artery harvest for coronary artery bypass grafting

Objective: Radial artery harvesting for coronary artery bypass may lead to digit ischemia if collateral hand circulation is inadequate. The modified A lien's test is the most common preoperative screening test used. Unfortunat ely, this test has high false-positive and false-negative rates. The purpos e of this study was to compare the results of a modified Alien's test with digit pressure change during radial artery compression for assessing collat eral circulation before radial artery harvest. Methods: One hundred twenty- nine consecutive patients were studied before coronary artery bypass operat ions. A modified Alien's test was performed with Doppler ultrasound to asse ss blood flow in the superficial palmar arch before and during radial arter y compression. A decreased audible Doppler signal after radial artery compr ession was considered a positive modified Alien's test. First and second di git pressures were measured before and during radial artery compression. A decrease in digit pressure of 40 mm Hg or more (digit Delta P) with radial artery compression was considered positive. Results: Seven of 14 dominant e xtremities (50%) and 8 of the 16 nondominant extremities (50%) with a posit ive modified Alien's test had a digit Delta P of less than 40 mm Hg (false positive). Sixteen of 115 dominant extremities (14%) and 5 of 112 nondomina nt extremities (4%) with a negative Alien's test had a digit Delta P of 40 mm Hg or more with radial artery compression (false negative). Conclusion: Use of the modified Alien's test for screening before radial artery harvest may unnecessarily exclude some patients from use of this conduit and may a lso place a number of patients at risk for digit ischemia from such harvest . Direct digit pressure measurement is a simple, objective method that may more precisely select patients for radial artery harvest. Additional studie s are needed to define objective digital pressure criteria that will accura tely predict patients at risk for hand ischemia after radial harvest.