[Importance of intrauterine diagnosis of rudimentary autonomic circulation in an acardiac twin].

Foetal acardia is a major complication of twin pregnancies which endangers the life of the healthy twin. The authors report the case of a twin pregnancy with an acardiac twin followed up by repeated echocardiography from the 20th week of pregnancy until delivery at the 36th week. Despite the presence of a parasitic mass, the healthy twin showed no sign of heart failure. Attentive ultrasonography of this mass showed a certain degree of autonomic circulation ensured by a rudimentary cardiac pump. This case confirms the favorable effect of this finding on the healthy twin, moreover, it clarifies some haemodynamic features of the parasitic mass: to-and-fro circulation, characteristic of a cardiac pump without a valve, anastomoses and competitive flow between the two circulatory systems.