F or infants having surgery for congenital heart disease, catheterization of the internal jugular vein (IJV) is done to monitor central venous pressure (CVP). Internal jugular vein catheterization is difficult in these young patients unless the cross-sectional area (CSA) of the IJV in infants and small children can be increased. Passive leg elevation (LE) and the Trendelenburg (T) position have been used in adults for this purpose but have not been thoroughly assessed in youngsters. This prospective observational study was performed to evaluate the effect of passive LE and T position on the CSA of the IJV in infants and young children undergoing heart surgery. The effect of passive LE was compared with that of the T position or both maneuvers combined. The effect of T positioning or LE on the CSA of the IJV was also compared in children with right-to-left (RL) shunt and left-to-right (LR) shunt.The 90 patients were aged from 10 days to 31 months and weighed 1.5 to 9.7 kg; 48 were in group RL, and 42 were in group LR. Anesthesia was induced with sodium pentothal and fentanyl and maintained with sevoflurane and remifentanil; endotracheal intubation was facilitated using rocuronium. The IVJ was imaged in the center of the ultrasound screen during each single or combination maneuver, each held for at least 30 seconds. For the T position, the table was tilted down to 15 degrees. Passive LE was performed by raising the legs 50 degrees for 30 seconds. The CSA was calculated by the planimetry method. All measurements were performed for the supine (S) position, T position, S position with passive LE, and T position with passive LE. After measurements were obtained, central venous catheterization was performed through the IJV by the Seldinger technique with ultrasound guidance. The initial CVP was measured and recorded for comparison between the groups. (In reporting the result, the term Bat least[ refers to the lower 95% confidence limits.)The 2 groups did not differ in demographic characteristics, age distributions, or initial CVP. The incidence of tricuspid regurgitation of more than mild grade and tricuspid annuloplasty was higher in the LR group compared with the RL group. The CSA of the right IJV was larger that that of the left IJV in more than 69.2% of the patients. The mean vertical diameter, transverse diameter, and CSA of the right IJV were larger than those of the left IJV in group LR for all positions. The CSA between the right and left IJV in group RL with T or LE positioning differed substantially. T, LE, and TLE positions increased the CSA of both the right and left IJV in group LR (at least 12.3%, 10.3%, and 18.3%, respectively in right IJV; at least 15.8%, 15.0%, and 18.9%, respectively, in left IJV). In group RL, the T or LE positions alone did not increase CSA of the IJVs. Only TLE increased the CSA of both IJVs (at least 8.2% and 7.7% in the right and left, respectively). The increase in the CSA of the right IJV related to T and TLE was larger in group LR than in group RL, at least 12.3% versus 1.2% fo...