Stuart Weiner

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

BACKGROUND By 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. METHODS AND RESULTS Blood 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. CONCLUSIONS The 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

BACKGROUND The 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. METHODS AND RESULTS Twenty 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. CONCLUSIONS Reactivity 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.

Antenatal diagnosis and early surgery for choledochal cyst

The pathogenesis and optimal treatment of choledochal cyst have long remained questions of considerable speculation and dispute. Because the pregnancy of a 37-year-old woman was felt to be at risk, five antenatal ultrasound examinations were made. The fourth examination at 31.5 weeks of gestation demonstrated a choledochal cyst. Following birth, the child was studied with repeat ultrasound examinations and scintigraphy. The results of these studies plus the findings at surgery contributed new evidence regarding the possible pathogenesis and optimal treatment of choledochal cysts. Although the time at which the cyst originated is compatible with the concept of reflux of pancreatic juice into the common duct, no abnormal junction of the pancreatic and common duct was identified. No evidence of obstruction as part of the pathogenesis could be demonstrated. Progressive changes in the choledochal cyst in the first ten days of life suggested that delay in diagnosis and treatment of a choledochal cyst may contribute to early complications such as cholangitis. Early excision of the cyst in the newborn is considered to be the optimal treatment and may pose less risk to the patient than delayed surgical exploration.

Ultrasonic ratio of fetal thoracic to abdominal circumference: An association with fetal pulmonary hypoplasia

Real time ultrasound was used in pregnant women who were considered to be at risk for development of pulmonary hypoplasia (n = 26). The population consisted of women who had either premature rupture of membranes (n = 16) or oligohydramnios (n = 10). The ratio calculated by comparing the fetal thoracic circumference to abdominal circumference was obtained in all cases within 10 days of delivery. This ratio correlated strongly with neonatal outcome. Multivariate regression models of neonatal outcome were developed to analyze the relationship of gestational age at which premature membrane rupture occurred, the duration of premature rupture, date of birth, and prenatal diagnosis. The addition of the thoracic circumference to the abdominal circumference ratio increased significantly the proportion of explained variability. Application of this ratio should be considered in evaluating fetal status in oligohydramnios and in the expectant management of premature rupture of membranes.

Landmarks during the first forty-two days of gestation demonstrated by the β-subunit of human chorionic gonadotropin and ultrasound

Prospective pregnancy evaluation through the combined use of a radioimmunoassay (RIA) for the beta-subunit of human chorionic gonadotropin (beta-hCG) and ultrasound during the first 42 days of gestation after ovulation was performed on a population asymptomatic for first-trimester spontaneous abortion. One hundred forty-six ultrasonic observations in 98 pregnancies were made with simultaneous beta-hCG RIA performed in 80 patients. The following landmarks of normal gestational growth were identified: (1) Before 26 days, beta-HCG RIA permits definitive diagnosis of growing trophoblastic tissue, and serial samples allow doubling time computation for prognosis while ultrasound shows a nonspecific increasing decidual response within the uterus; (2) between 26 and 36 days after ovulation, serial beta-hCG samples continue to give doubling time results while ultrasonic demonstration of a gestational sac is normally seen by 28 days after ovulation; (3) the lack of fetal heart motion by 42 days after ovulation or within a gestational sac with a mean diameter of greater than 30 mm was prognostic of abortion; (4) the absence of a gestational sac by 28 days after ovulation or with a beta-hCG RIA greater than 1,000 ng/ml is suggestive of an ectopic pregnancy until proved otherwise.

The effect of improvement of umbilical artery absentend-diastolic velocity on perinatal outcome

OBJECTIVES The purpose of this study was to analyze cases in which antenatal improvement of absent fetal umbilical artery end-diastolic velocity was detected and to correlate improvement with perinatal outcome. STUDY DESIGN Forty cases of umbilical artery absent end-diastolic velocity in singleton pregnancies were retrospectively reviewed. Maternal characteristics and perinatal outcomes were compared in cases where improvement of end-diastolic velocity was diagnosed and those in which no improvement was detected. RESULTS Eleven cases of absent end-diastolic velocity showed antenatal improvement and were associated with more advanced gestational age at delivery, longer diagnosis-to-delivery interval, larger birth weights, and a lower incidence of neonatal death than those fetuses without antenatal improvement. CONCLUSION Improvement of umbilical artery absent end-diastolic velocity can occur and is associated with improved pregnancy outcome when compared with patients without antenatal improvement of diastolic velocity.

Maternal and fetal plasma vitamin E to total lipid ratio and fetal RBC antioxidant function during gestational development.

Placental transfer of vitamin E was investigated from 19 to 35 weeks of gestation by analysis of fetal and maternal blood samples for total tocopherol, total lipids, and fetal red blood cell antioxidant reserves. Fifty-two fetal blood samples were obtained under ultrasonographic guide by percutaneous umbilical blood sampling. Thirteen were from fetuses with gestational age less than or equal to 22 weeks (x serum vitamin E = 0.4 +/- 0.14 mg/dl), 12 were from fetuses at 23-27 weeks gestation (x serum vitamin E = 0.4 +/- 0.21 mg/dl), and 27 were from fetuses with gestational age 28-38 weeks (x serum level = 0.37 +/- 0.18). Total lipid levels ranged from 140 to 216 mg/dl. Maternal plasma vitamin E concentrations correlated significantly with concurrent values in the fetus. There were no significant differences in serum vitamin E levels or vitamin E to total lipid ratio in samples from early, mid, or late gestation in either the mother or fetus. Red blood cell antioxidant reserve on samples from 18 fetuses were grossly abnormal by three different functional assays. On the basis of these data, placental transfer of vitamin E appears to be relatively constant through advancing gestation. Red blood cell antioxidant reserve is uniformly low.

Lung hypoplasia and prolonged preterm ruptured membranes: A case report with implications for possible prenatal ultrasonic diagnosis

Oligohydramnios as the cause of the nonrenal features of Potter’s syndrome has been reported by Thomas and Smith.’ Their “oligohydramnios tetrad of anomalies” included facial and ear anomalies, limb positioning defects, growth retardation, and, most important for the survival of the fetus, lung hypoplasia.’ With the trends toward observation and expectant management in preterm rupture of the membranes, the association of oligohydramnios and lung hypoplasia becomes increasingly important. The following case illustrates an infant with lung hypoplasia following prolonged rupture of membranes.

The influence of ovarian denervation and nerve stimulation on ovarian contractions.

Two techniques were used to study the neuromuscular control of rabbit ovarian contractions. First, the ovary was denervated by stripping its artery. Spontaneous contractions were noted, as was a normal response to exogenously administered adrenergic agents. Second, the ovarian nerves were electrically stimulated in an in vitro perfused ovary system. Inhibition of ovarian contractions was noted, and the additive effects with adrenergic agents suggested a betamimetic effect of nerve stimulation in the estrous rabbit. After administration of exogenous human chorionic gonadotropin, the response was reversed. The significance of the contribution of a neuromuscular mechanism to the control of ovulation is discussed.

Selective Ovarian Sympathectomy in the Rabbit

Evidence implicates the ovarian nerves in the regulation of hormonal and ovulatory functions. A technique for selectively denervating the in situ rabbit ovary is therefore of considerable investigative value. The ovarian artery was stripped of its adventitia and nerve bundles. Three weeks later, fluorescent histochemistry confirmed the complete absence of adrenergic nerves in the vessel walls and ovarian stroma of the experimental ovary, as compared to the abundant fluorescent structures present in the contralateral control ovary. The surgically treated ovaries demonstrated no significant ischemic or trophic change on gross and routine histologic examination.