Cavoatrial junction and central venous anatomy: implications for central venous access tip position.

PURPOSE: To quantify the anatomic relationships of the cavoatrial junction and propose a system for describing central venous access device tip location on the basis of structures visible on chest radiographs.
MATERIALS AND METHODS: The authors performed a retrospective study of 100 consecutive computed tomographic (CT) studies from a predominantly pediatric population consisting of 52 male and 48 female patients aged 12-28 years (mean age, 16 years). With use of multiplanar and scout images, relevant mediastinal structures were marked, vertebral levels were noted, and measurements were made electronically. Catheter tip positions were recorded in the 26 children who had central catheters.
RESULTS: A vertebral body unit was defined as the distance between the inferior endplate of one vertebra to the inferior endplate of the next, with the upper intervertebral disk included. The most reliable estimate of cavoatrial junction position is a point two vertebral body units below the carina; there was no association with patient age or other parameters.
CONCLUSIONS: A more accurate understanding of the superior vena cava anatomy is essential for the correct interpretation of central venous access device position. The true cavoatrial junction is located more inferiorly than commonly believed and is not accurately estimated with commonly used imaging landmarks. A point two vertebral body units below the carina enables the reliable estimate of the position of the cavoatrial junction. Catheter tip position can be most reliably described in vertebral body units below the carina, with use of the thoracic spine as an internal ruler.