Role of systolic blood pressure gradient of limb test in diagnosing neonatal aorta anomaly

Abstract

Objective To determine the effectiveness of systolic blood pressure gradient between the right arm and the right leg(SBPG) tests in the diagnosis of neonatal aorta anomaly(AoA). Methods The SBPG of infants suspected of having critical congenital heart diseases were collected prospectively, who were admitted to Guangdong General Hospital from January 2013 to December 2015.The results of SBPG test were compared with those of echocardiography or cardiac computed tomography (golden standard). The rates of true positive, true negative, false positive, false negative were calculated under cutoff values of 5 mmHg(1 mmHg=0.133 kPa), 10 mmHg, 15 mmHg and 20 mmHg, respectively.Receiver operating characteristic (ROC) curves was used to compare tests of different cutoff and the areas under the ROC curve were also calculated. Results Among 664 enrolled infants, 67 cases were confirmed by golden standard test.The systolic blood pressure in the right arm, the legs and SBPG in AoA group and non-AoA group were (88.0±20.4) mmHg vs.(73.4±9.3) mmHg (P 0.05) and (22.6±17.8) mmHg vs.(2.3±4.8) mmHg(P<0.01), respectively.In these patients, 31 cases(46.3%), 31 cases(46.3%), 27 cases(40.3%) and 21 cases(31.3%) were diagnosed of AoA, and 36 cases(53.7%), 36 cases(53.7%), 40 cases(59.7%), and 46 cases(68.7%) were missed by SBPG tests of 5 mmHg, 10 mmHg, 15 mmHg and 20 mmHg, respectively (P<0.01). The rates of true negative among those groups were 94.1%, 99.5%, 99.7% and 100.0%, and the areas under ROC curve were 0.656, 0.722, 0.695 and 0.657, respectively (P<0.01). Conclusions Almost half of AoA infants could be screened out by SBPG test.The cutoff of 10 mmHg could probably be used to screen potential AoA infants, with higher true positive rate and lower false positive rate. Key words: Blood pressure; Coarctation of the aorta; Interrupted aortic arch; Aorta anormaly; Diagnosis; Congenital heart disease