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 Alien's test is the most common preoperative screening test used. Unfortunately, this test has high false-positive and false-negative rates. The purpose of this study was to compare the results of a modified Alien's test with digit pressure change during radial artery compression for assessing collateral circulation before radial artery harvest. Methods: One hundred twenty-nine consecutive patients were studied before coronary artery bypass operations. A modified Alien's test was performed with Doppler ultrasound to assess blood flow in the superficial palmar arch before and during radial artery compression. A decreased audible Doppler signal after radial artery compression was considered a positive modified Alien's test. First and second digit 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 extremities (50%) and 8 of the 16 nondominant extremities (50%) with a positive 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 nondominant 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 also 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 studies are needed to define objective digital pressure criteria that will accurately predict patients at risk for hand ischemia after radial harvest.