Juha Rasanen

Role of the Pulmonary Circulation in the Distribution of Human Fetal Cardiac Output During the Second Half of Pregnancy

BACKGROUNDnBy using Doppler echocardiography, we determined the normal distribution of human fetal combined cardiac output (CCO) from the left and right ventricles. We also established weight-indexed pulmonary and systemic vascular resistances (Rpi and Rsi, respectively) and changes during the second half of pregnancy.nnnMETHODS AND RESULTSnBlood flows at the aortic and pulmonary valve annuli (LVCO and RVCO, respectively), right and left pulmonary arteries (QP), and ductus arteriosus (QDA) were calculated in 63 normal fetuses. Foramen ovale blood flow (QFO = LVCO-QP) was estimated. From 20 to 30 weeks of gestation, the proportion of QP of the CCO increased (from 13% to 25%, P < .001), while the proportion of QFO decreased (from 34% to 18%, P < .001). After 30 weeks, the proportions of QP and QFO were unchanged. At 38 weeks, the proportion of RVCO (60%) was higher (P < .05) than that of LVCO (40%). The proportion of QDA did not change significantly. The correlation between RVCO calculated from blood flow through the pulmonary valve and from QDA and QP was good (r = .97, P < .0001). RPi (P < .001) decreased from 20 to 30 weeks of gestation. From 30 to 38 weeks, RPi increased (P < .0001). Rsi increased (P < .001) from 20 to 38 weeks. The ratio of RPi to RSi decreased (P < .01) from 20 to 30 weeks and later remained unchanged.nnnCONCLUSIONSnThe human fetal pulmonary circulation has an important role in the distribution of cardiac output.

Reactivity of the Human Fetal Pulmonary Circulation to Maternal Hyperoxygenation Increases During the Second Half of Pregnancy A Randomized Study

BACKGROUNDnThe aims of the present study were to determine whether maternal hyperoxygenation affects human fetal pulmonary circulation and whether there is a gestational age-related response in the fetal pulmonary circulation to maternal hyperoxygenation during the second half of gestation.nnnMETHODS AND RESULTSnTwenty women between 20 and 26 weeks of gestation and 20 women between 31 and 36 weeks of gestation with normal singleton pregnancies were randomized to receive either 60% humidified oxygen or medical compressed air (room air) by a face mask. Fetal aortic and pulmonary valve; ductus arteriosus (DA); and right (RPA), left (LPA), and distal (DPA) pulmonary artery blood velocity waveforms were obtained by Doppler ultrasound before, during, and after maternal administration of either 60% oxygen or room air. Left and right ventricular cardiac outputs, DA volume blood flow, and RPA and LPA volume blood flows (Qp) were calculated. Foramen ovale volume blood flow (left ventricular cardiac output-Qp) was estimated. Pulsatility index (PI) values of DA, RPA, LPA, and DPA were calculated. Maternal hyperoxygenation did not change any of the measured fetal parameters between 20 and 26 weeks, whereas between 31 and 36 weeks, the PI values of RPA, LPA, and DPA decreased (P<.0001) and the PI of DA increased (P<.0001). In addition, Qp increased (P<.001), and DA volume blood flow (P<.01) and foramen ovale volume blood flow (P<.03) decreased. Left and right ventricular cardiac outputs were unchanged. All changes returned to baseline after maternal hyperoxygenation was discontinued.nnnCONCLUSIONSnReactivity of the human fetal pulmonary circulation to maternal hyperoxygenation increases with advancing gestation; this suggests that fetal pulmonary circulation is under acquired vasoconstriction at least after 31 to 36 weeks of gestation.

OC06.02: Can myocardial contractility be assessed by tissue Doppler imaging? An experimental study in an acute fetal sheep model

G. Acharya1, J. Gutierrez2, T. Erkinaro3, M. Haapsamo4, K. Makikallio4, J. C. Huhta5, J. Rasanen4 1Obstetrics and Gynecology, University of Tromso and University Hospital of Northern Norway, Tromso, Norway; 2Unidad Materno Infantil, Clinica Universitaria Bollivariana, Universidad Pontificia Bolivariana, Medellin, Colombia; 3Anesthesiology, University Hospital of Oulu, Oulu, Finland; 4Obstetrics and Gynecology, University Hospital of Oulu, Oulu, Finland; 5Pediatrics, University of South Florida and All Children’s Hospital, St. Petersburg, FL, USA