Reliability of systolic time intervals in diagnosis of transposition of great arteries in newborn.

SUMMARY The diagnostic echocardiographic features of transposition of the great arteries have been described as (1) abnormal great vessel relations, (2) reversed systolic time intervals. The former has been shown to be unreliable and the systolic time intervals have not been critically evaluated in the neonate. A cardiac opinion was sought in 17 cyanotic neonates, aged 7 to 80 hours in whom full clinical examinations, electrocardiogram, and chest x-ray could not distinguish between transposition of the great arteries and respiratory disease. Nine patients (group 1) had the former and eight (group 2) had the latter. Standard echocardiograms were performed taking note of the great vessel relations, and systolic time intervals were measured. Reversed systolic time intervals were present (a) when the anterior root pre-ejection period was equal to or greater than the posterior root pre-ejection period, or (b) when the anterior root ejection time was equal to or shorter than the posterior root ejection time, or (c) when the anterior root electromechanical systole was equal to or shorter than the posterior root electromechanical systole, or (d) when the anterior root pre-ejection period/ejection time ratio was equal to or greater than the posterior pre-ejection period/ejection time ratio. When the great vessel relations were clearly reversed, that is the anterior root was medial, cephalad, and anterior to the posterior root, then the positions were diagnostic for transposition ofthe great arteries; other relations were either non-diagnostic or clearly normal. The sensitivity, specificity, and predictive accuracy of these findings were calculated. The great vessel relations were determined with 78% sensitivity, 87-5% specificity, and 87-5% predictive accuracy. The systolic time intervals criteria were 44 to 89% sensitive, 0 to 50% specific, and had 50 to 66% predictive accuracy. Thus, taken alone, systolic time intervals are useless in excluding transposition. By linear discriminant analysis using both the great vessel relation and systolic time intervals a formula was derived which would have predicted the diagnosis with 100% accuracy. This requires a prospective study for proof of its validity. In the meantime, careful evaluation of all the clinical, laboratory, and echocardiographic data must be made in any cyanosed neonate and cardiac catheterisation must not be delayed if the diagnosis is in doubt. Balloon atrial septostomy has dramatically changed the catheterisation. The echocardiographic features of immediate prognosis for neonates with d-transposition transposition of the great arteries are said to be (1) an of the great arteries but this procedure …