Venous Doppler in the sonographic surveillance of fetuses with supraventricular tachycardia

Objective: In animals and adult humans sustained supraventricular tachycard ia leads to myocardial remodelling and dysfunction, persisting even after d rug-induced cardioversion to sinus rhythm. This study was undertaken, to ev aluate cardiac function in the human fetus by noninvasive determination of the degree of AV valve incompetence and venous blood flow, in order to enha nce understanding of the pathophysiology of fetal supraventricular tachycar dia. Furthermore, we wanted to determine the usefulness of these methods in the surveillance of these fetuses before and after drug-induced cardiovers ion. Study design: Eleven fetuses with supraventricular tachycardia between 24 and 35 weeks of gestation were studied. AV valve regurgitation and veno us Doppler waveforms of the inferior vena cava and ductus venosus were eval uated before and after conversion to sinus rhythm. Results: Three different groups of fetuses could be distinguished. The first group consisted of fou r fetuses with neither signs of hydrops nor AV valve incompetence. Venous i ndices normalized within one to four days (median 2.5 days) after conversio n to sinus rhythm. The second group contained two fetuses with hydrops, but without AV valve incompetence. Their venous indices normalized at the day of conversion and 3 days later, respectively (median 1.5 days). The last gr oup of five fetuses consisted of four fetuses with hydrops and AV valve reg urgitation during supraventricular tachycardia. In one fetus with hydrops a nd supraventricular tachycardia the fetal heart rate was continuously decre ased to a level of 160-190 beats/min under drug treatment, but no conversio n to sinus rhythm occurred. The venous indices of these fetuses normalized within 12-42 days (median 27 days) after conversion Conclusion: Our data su ggest that in sustained fetal supraventricular tachycardia alterations of m yocardial function similar to tachycardia-induced 'cardiomyopathy' occur. T he severity of tachycardia-induced changes of cardiac function is reflected by the degree and persistence of AV valve incompetence, as well as by alte rations of the venous blood flow pattern. Under clinical conditions, the la tter can readily and well reproducibly be demonstrated by calculating the v enous blood flow indices of the inferior vena cava and ductus venosus. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.