CT angiography of the superior vena cava: normative values and implications for central venous catheter position.

PURPOSE: To determine normative data for radiographic landmarks of the superior vena cava (SVC) and the location of the junction of the SVC with the right atrium for use in the placement of central venous catheters.

MATERIALS AND METHODS: The authors retrospectively reviewed 112 pulmonary computed tomographic (CT) angiograms obtained in seven men and seven women from each decade of life between the ages of 20 and 99 years. For each patient, the length of the SVC was measured from its origin to the cavoatrial junction. The distances from the carina and right tracheobronchial angle to the cavoatrial junction and the origin of the SVC were also measured. Interobserver variation in choosing the location of the carina and tracheobronchial angle was analyzed.

RESULTS: The mean length (+/-standard deviation) of the SVC was 70.7 mm +/- 14.1. The mean distance from the superior margin of the SVC to the carina was 30.4 mm +/- 11.2, from the carina to the cavoatrial junction 40.3 mm +/- 13.6, from the superior margin of the SVC to the right tracheobronchial angle 21.7 mm +/- 10.8, and from the right tracheobronchial angle to the cavoatrial junction 49.0 mm +/- 13.6. There was a statistically significant difference in interobserver variation in selecting the location of the right tracheobronchial angle as compared to choosing the carina.

CONCLUSION: Placement of the central venous catheter tip at or just below the level of the carina during inspiration ensures placement in the SVC. Placement of the central venous catheter tip approximately 4 cm below the carina will result in placement near the cavoatrial junction.