MRI OF CENTRAL VENOUS ANATOMY - IMPLICATIONS FOR CENTRAL VENOUS CATHETER INSERTION

Study objectives: To determine normative values for superior vena cave (SVC) length and the utility of radiographic landmarks for identifyin g the boundaries of the SVC for assisting central line placement. Desi gn: Cross-sectional study. Setting: Urban tertiary care medical center s. Patients: Patients undergoing thoracic MRI scanning for various ind ications. Interventions: None. Measurements and results: The SVC dimen sions and relationship to radiographic landmarks were determined from MRI scans of 42 patients (22 men, 20 women; median age, 57 years). The median length of the SVC was 6.8 cm (range, 4.4 to 10.0 cm) and did n ot correlate with gender or other measured cardiovascular dimensions. The right tracheobronchial angle was the best radiographic landmark fo r determining the cephalad origin of the SVC being always caudad and w ithin a median of 1.5 cm (range, 0.1 to 3.8 cm) of the upper SVC. It w as always at least 2.9 cm above the atriocaval junction, The right sup erior heart border was formed by the left atrium in 38% (95% confidenc e interval, 23 to 53%) of patients and did not reliably identify the a triocaval junction. Conclusions: The right tracheobronchial angle is t he most reliable landmark for the upper margin of the SVC, Venous cath eters placed caudad to this landmark and cephalad to the right superio r cardiac silhouette or no more than 2.9 cm caudad to the tracheobronc hial angle result in catheter tips within the SVC.