COMPARATIVE VALUE OF TRANSTHORACIC ECHOCA RDIOGRAPHY AND ANGIOGRAPHY FOR MEASURING THE PULMONARY-ARTERY ANNULUS IN TETRALOGY OF FALLOT

It may be necessary to perform an enlarging pulmonary annuloplasty dur ing surgical cure of Tetralogy of Fallot (TOF) in order to optimise re construction of the right ventricular outflow tract. As this additiona l procedure implies an increase in perioperative mortality, it is usef ul to prepare for this eventuality before surgery. Two imaging techniq ues are available: transthoracic echocardiography (diameter of the pul monary annulus obtained by averaging the measurements obtained in the subcostal and parasternal short axis views of the insertion of the pul monary valve cusps at end systole) and selective angiography during ri ght heart catheterisation (anteroposterior measurement with comparison to be projected and real size of the catheter at the point of inserti on of the cusps at end systole). In this study, these two techniques w ere compared with reference to the peroperative measurement with Hegar dilators and criteria defined by Naito (minimal diameter of the pulmo nary artery annulus with respect to the weight of the child). Seventy- eight children admitted to hospital between January 1986 and April 199 4 for curative surgery of TOF were included. The calculation of the in tra-class correlation coefficient showed a mediocre correlation with a ngiography and a very mediocre correlation with echocardiography compa red with peroperative measurements. However, the calculation of sensit ivities showed angiography to be the predictive investigation for annu loplasty in children not conforming to the Naito criteria: higher sens itivity (83% vs 26 % for echocardiography), greater negative predictiv e value (84 % vs 70 %). This result holds for all categories of body w eight (over and under 10 kg). Conversely, and probably due to a tenden cy to overestimate the size of the pulmonary artery ring, echocardiogr aphy is a very specific technique for the prediction of annuloplasty ( 99 % vs 64 %). In this indication (the determination of the best predi ctive technique for this procedure during complete correlation of TOF) , angiography still seems to be the most sensitive diagnostic imaging technique.