MORPHOMETRIC ASSESSMENT OF THE INNOMINATE VEIN IN THE PREDICTION OF PERSISTENT LEFT SUPERIOR VENA-CAVA

This study sought to develop a simple echocardiographic predictor of p ersistent left (L) superior vena cava (SVC) in subjects with bilateral SVC. Two groups of children were studied: one with known LSVC (II = 1 9) and the other, a control group, without LSVC (n = 15). Both groups were of similar age (3.5 +/- 3.0, mean +/- SD vs 3.8 +/- 3.1 years; p = 0.8) and weight (14.6 +/- 7.1 vs 15 +/- 8 kg; P = 0.9). The left inn ominate vein was either absent (II = 11) or hypoplastic (rt = 8) in th e LSVC group. The ratio of the innominate vein to the innominate arter y was found to be independent of age or body surface area but was sign ificantly smaller in the LSVC group than in the control group (0.33 +/ - 0.1 vs 0.97 +/- 0.1; p < 0.001). A cutoff value of 0.47 or less disc riminated the LSVC group from the control subjects. Interobserver and intraobserver variations, although important, did not influence the di scriminating value of the ratio in the diagnosis of LSVC. Validation o f the proposed ratio in 30 consecutive prospectively studied patients with LSVC proved to be 100% sensitive in predicting LSVC. No false-pos itive diagnosis of LSVC was made when this principle was applied. Abse nt or hypoplastic left innominate vein measuring 0.47 or less of the i nnominate artery is an easily recognizable and reliable echocardiograp hic predictor of LSVC.