OP04.23: Impaired systolic and diastolic ventricular function after permanent extra‐embryonic venous obstruction, a pressure‐volume loop assessment in the stage‐24 chick embryo

Abstract

Hydrops fetalis is the final common hemodynamic pathway for a variety of pathological states in the fetus, including high output states associated with fetal anemia or arterio-venous fistulas and abnormalities of both cardiac structure and rhythm. Hydrops fetalis secondary to cardiovascular decompensation is usually accompanied by elevations in fetal systemic venous pressure as evidenced by alterations in venous Doppler waveforms. We present two cases of severe fetal aortic stenosis with left ventricular fibroelastosis and mitral regurgitation and in utero closure or stenosis of the foramen ovale, with severe hydrops fetalis, despite normal systemic venous Doppler flow profiles. Both cases demonstrated markedly abnormal fetal pulmonary venous Doppler waveforms and after birth, both infants were hypoalbuminemic. The presence of normal systemic venous Doppler waveforms in fetuses with severe hydrops fetalis and structural cardiac disease challenges our understanding of the etiology of this pathological state. These cases have led us to reconsider the presumed etiology of cardiogenic hydrops fetalis in fetuses with severely impaired left ventricular pump function and secondary mitral regurgitation. We hypothesize that elevated pulmonary venous pressure, with only mildly increased central venous pressure, may negatively impact pulmonary lymphatic flow, decrease serum oncotic pressure due to loss of protein-rich fluid in the pulmonary interstitium, increase venous hydrostatic pressure, and lead to hydrops fetalis.