Bedside Vein Mapping for Conduit Size in Coronary Artery Bypass Surgery

The greater saphenous vein has been used in coronary artery bypass grafting (CABG) for more than 50 years. Endoscopic vein harvesting has greatly reduced the morbidity associated with obtaining the vein, but the quality of the vein could not be assessed before its was exposed surgically or after the endoscopic procedure had been performed. This study was conducted to evaluate the accuracy of preoperative mapping of the greater saphenous vein at the bedside in assessing suitable conduit size for use in CABG.

Seventy-two consecutive patients undergoing saphenous vein harvesting for use as a conduit during CABG underwent preoperative ultrasonographic vein mapping on the operating table after the leg was positioned for vein harvesting. Vein diameters at 3 distinct locations were measured by ultrasonography after vein harvesting and preparation. Similar linear regression was used to determine the correlation between measurements by ultrasonography and the true vein size after harvesting. Standard methods of computing 95% lower and upper confidence limits for single predicted values were also used.

Two hundred twenty measurements were obtained from 72 patients. Mean vein diameters were 3.4 ± 0.9 and 4.6 ± 0.9 mm as measured by ultrasonography and after vein harvest, respectively. True vein size was an average of 1.2 ± 0.4 mm larger than that measured by ultrasonography. Ultrasonographic determination of vein diameters closely correlated with the true vein diameter (correlation coefficient, 0.91; P < .001), and the measurement obtained predicted the true measurement within 1.6 mm with 95% confidence.

Bedside ultrasonographic vein mapping provides an accurate noninvasive method for preoperative assessment to determine the suitability of the greater saphenous vein for use as a bypass conduit. It is therefore an important component of preoperative planning before CABG.