[Blood flow through the fetal aortic isthmus: a new physiological concept with many clinical implications].
The new physiological concept: because of the parallel disposition of the fetal ventricles and of their respective arterial outlet, the flow through the aortic isthmus represents the only arterial shunt in the fetal circulation. The low resistance of the placental circulation explains the forward systolic and diastolic flows normally observed through the isthmus.


CONCLUSIONS
(1) assessment of individual performances of each ventricle : left ventricle causes forward flow while the right ventricle has a retrograde influence; (2) any changes of flow and/or resistances affecting one of the two fetal arterial systems organized in parallel should influence the flow pattern within the isthmus. Examples : peripheral arterio-venous fistula, increase in placental vascular resistance leading to intra-uterine growth restriction, etc.


CONCLUSIONS
doppler flow recordings in the fetal aortic isthmus: (1) provides information on the global condition of the fetal cardiocirculatory system; (2) is a good indicator of fetal individual ventricular performance; (3) allows assessment of hemodynamic consequences of abnormalities of the peripheral circulatory systems.
Fouron
Jean-Claude
JC
Unité de Cardiologie Foetale, Service de Cardiologie, CHU Sainte-Justine, 3175, chemin de la Côte Sainte-Catherine, Montréal, Québec H3T 1C5, Canada. fouron@sympatico.ca
D001013:Aorta, Thoracic / Q000196:embryology* / Q000502:physiology*; D001783:Blood Flow Velocity; D002320:Cardiovascular Physiological Phenomena; D005260:Female; D006321:Heart / Q000196:embryology / Q000502:physiology; D006801:Humans; D011247:Pregnancy