VENTRICULOATRIAL TIME-INTERVAL MEASURED ON M-MODE ECHOCARDIOGRAPHY - A DETERMINING ELEMENT IN DIAGNOSIS, TREATMENT, AND PROGNOSIS OF FETAL SUPRAVENTRICULAR TACHYCARDIA

Objective-To determine whether M mode echocardiography can differentia te fetal supraventricular tachycardia according to the ventriculo-atri al (VA) time interval, and if the resulting division into short and lo ng VA intervals holds any relation with clinical presentation, managem ent, and fetal outcome. Design-Retrospective case series. Subjects-23 fetuses with supraventricular tachycardia. Main outcome measures-A sys tematic review of the M mode echocardiograms (for VA and atrioventricu lar (AV) interval measurements), clinical profile, and final outcome. Results-19 fetuses (82.6%) had supraventricular tachycardia of the sho rt VA type (mean (SD) VA/AV ratio 0.34 (0,16); heart rate 231 (29) bea ts/min). Tachycardia was sustained in six and intermittent in 13. Hydr ops was present in three (15.7%), Digoxin, the first drug given in 14, failed to control tachycardia in five. Three of these then received s otalol and converted to sinus rhythm. Ah fetuses of this group survive d. Postnatally, supraventricular tachycardia recurred in three, two ha ving Wolff-Parkinson-White syndrome. Four fetuses (17.4%) had long VA tachycardia (VA/AV ratio 3.89 (0.82); heart rate 226 (10) beats/min). Initial treatment with digoxin was ineffective in all, but sotalol was effective in two. Heart failure caused fetal death in one and prematu re delivery in one. All three surviving fetuses had recurrences of sup raventricular tachycardia after birth: two had the permanent form of j unctional reciprocating tachycardia and one had atrial ectopic tachyca rdia. Conclusions-Careful measurement of ventriculo-atrial intervals o n fetal M mode echocardiography can be used to distinguish short from long VA supraventricular tachycardia and may be helpful in optimising management. Digoxin, when indicated, may remain the drug of choice in the short VA type but appears ineffective in the long VA type.