Doppler echocardiographic studies of diastolic function in the human fetal heart: changes during gestation.

With the combined use of two-dimensional ultrasound and Doppler echocardiography, noninvasive examination of the human fetal heart and circulation has recently become possible. These techniques were employed to investigate diastolic atrioventricular valve flow in the fetal heart in 120 fetuses studied between 17 and 42 weeks of gestation. Two-dimensional ultrasound was used to examine fetal and intrauterine anatomy, and estimates of gestational age were made based on biparietal diameters and femur lengths. Doppler echocardiography was performed with a 3.5 or 5 MHz Doppler sector scanner. Flow velocity patterns were obtained through the tricuspid and mitral valves during diastole. Peak flow velocity during late diastole or atrial contraction (A) was compared with peak flow velocity during early diastole (E) in four groups of fetuses: Group 1, 17 to 24 weeks of gestation; Group 2, 25 to 30 weeks; Group 3, 31 to 36 weeks; and Group 4, 37 to 42 weeks. The ratio of A to E decreased significantly as gestational age advanced, from 1.56 +/- 0.06 (+/- SE) to 1.22 +/- 0.03 across the tricuspid valve (p less than 0.001) and from 1.55 +/- 0.04 to 1.22 +/- 0.06 across the mitral valve (p less than 0.001). In tricuspid valve measurements, peak flow velocity during early diastole increased from 26.3 +/- 2.0 cm/s in Group 1 to 36.5 +/- 1.7 cm/s in Group 4 (p less than 0.001), whereas peak flow velocity during atrial contraction did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Paraquat-induced formation of leukotriene B4 in rat lungs: modulation by N-acetylcysteine.

The present work is focused on the formation of the inflammatory mediator leukotriene B4 (LTB4) in the lungs of paraquat (PQ)-intoxicated rats. The levels of LTB4 and the number of neutrophils in lung lavages of PQ-intoxicated rats, measured 12 h after 30 mg/kg PQ, increased significantly compared with those of control animals; administration of 50 mg/kg IP N-acetylcysteine (NAC), 8 h after PQ, inhibited this effect. The release of LTB4 from alveolar macrophages (AM) or alveolar epithelial type II cells from healthy animals incubated with PQ and/or NAC did not offer' an explanation for the effect of these chemicals on LTB4 in the bronchoalveolar lavage fluid (BALF). The PQ-enhanced, NAC-inhibited release of arachidonic acid (AA) by alveolar epithelial type II cells did, however, explain our in vivo results, when one assumes that the AM synthesize their 5-lipoxygenase products from alveolar epithelial cell-derived AA, an hypothesis demonstrated already by other researchers.

Fetal pulmonary artery and aorta: two-dimensional Doppler echocardiography.

Two-dimensional and pulsed Doppler ultrasound techniques were used to examine 87 fetuses between 17 and 41 weeks' gestation in order to compare pulmonary artery and aortic outflow diameters, mean and maximal flow velocities, and transvalve flows. For purposes of analysis, fetuses were divided into two groups: those less than 31 weeks, and those of 31 weeks or more. Diameters of the pulmonary artery and aortic outflow region increased with advancing gestational age (P less than .001), while mean and maximal Doppler flow velocities did not change. Transvalve volume flow increased across both regions (pulmonary artery from 381 +/- 12 mL/minute to 530 +/- 13 mL/minute and aortic outflow from 286 +/- 10 mL/minute to 410 +/- 13 mL/minute, P less than .001) with advancing gestation. Pulmonary artery diameters were larger than aortic outflow diameters in both groups (P less than .01), while mean Doppler flow velocities were not significantly different. Maximal Doppler flow velocities were greater in the aorta than in the pulmonary artery (P less than .001), and transvalve flow was greater across the pulmonary artery than the aorta in both groups (P less than .05, ratio 1.3:1). This work demonstrates differences in fetal pulmonary artery and aortic outflow anatomy and physiology that must be considered in evaluating studies of fetal cardiac physiology.

Effect of long-term oral contraceptive therapy before pregnancy on maternal and fetal zinc and copper status.

Thirteen pregnant women who conceived within six months after terminating oral contraceptive agent therapy of at least three years' duration participated in this study. Nine pregnant women with no history of oral contraceptive agent use served as controls. At delivery, erythrocyte counts were reduced, and during the first trimester and at delivery mean corpuscular hemoglobin and volume values were increased and erythrocyte zinc values were reduced in the oral contraceptive agent group as compared with controls. These changes appeared to be subclinical in magnitude and oral contraceptive agents may have induced a macrocytic erythrocyte population. Because no changes in maternal plasma zinc and copper levels were observed and no hematologic, biochemical, or anthropometric differences were observed in neonates, long-term oral contraceptive agent usage appeared to have little or no effect on zinc and copper metabolism in a subsequent pregnancy.

Routine electronic monitoring of fetal heart rate and uterine activity during labor.

Routine electronic monitoring has been performed on 2411 labor patients at Booth Memorial Medical Center. Most recently, 88% of all patients delivered were monitored. As a direct result of this program, intrapartum stillbirths have been dramatically reduced from 1.2/1000 livebirths to 0.5/1000 livebirths. Perinatal mortality for fetuses over 1000 g has fallen to 8.8/1000 deliveries. Apgar scores below 6 at 5 minutes have decreased from a rate of 24/1000 to 14/1000 livebirths. No increase in cesarean sections for fetal distress has occurred although the primary cesarean section rate has increased over the past 10 years, apparently unrelated to fetal monitoring. It is strongly recommended that all patients in labor be monitored by currently available technics.

Prenatal diagnosis of congestive heart failure in a fetus with a sacrococcygeal teratoma.

Two-dimensional Doppler echocardiography was used to diagnose congestive heart failure in a fetus with a large sacrococcygeal teratoma. Ultrasound performed for size-date inconsistency revealed a 27.5-week fetus with hydrops and a large solid and cystic mass in the sacral region. Fetal echocardiography showed dilated ventricles and a pericardial effusion; Doppler ultrasound demonstrated increased velocities and volume flows, along with tricuspid and mitral regurgitation. At delivery, the mass was bleeding actively, the amniotic fluid was markedly bloody, and the neonatal hematocrit was 10%. We postulate that intrauterine hemorrhage from the teratoma led to anemia and high-output cardiac failure confirmed by Doppler echocardiography, and suggest that all fetuses with sacrococcygeal teratomas be evaluated by two-dimensional Doppler echocardiography to detect the presence of congestive heart failure, in order to allow well-timed therapeutic interventions.

Cardiac Doppler flows during fetal arrhythmias: physiologic consequences.

Eighty-six fetuses of 21-41 weeks' gestation with arrhythmias were studied with ultrasound and heart rate monitoring. The type of arrhythmia was identified by M-mode studies and was confirmed by postnatal electrocardiogram in 70 infants. The most common arrhythmia was premature atrial contractions (76), followed by premature ventricular contractions (five), paroxysmal supraventricular tachycardia (four), and atrial fibrillation/flutter (one). Doppler echocardiography was performed in 54 fetuses to measure flow velocities across the atrioventricular and semilunar valves. After isolated premature atrial and ventricular contractions, post-extrasystolic potentiation was demonstrated by an increase in fractional shortening (N = 32) of 49 +/- 6% in the right ventricle and 64 +/- 7% in the left ventricle. When post-extrasystolic beats were compared with normal beats, Doppler-determined time-velocity integrals increased 43% across the tricuspid valve, 41% across the mitral valve, 34% across the pulmonary valve, and 38% across the aortic valve. Mean velocity increased significantly after conversion to normal sinus rhythm in the five fetuses with supraventricular tachycardia (P less than .05). By studying the physiologic consequences of fetal arrhythmias using two-dimensional Doppler and M-mode ultrasound, we have documented the presence of post-extrasystolic potentiation after premature contractions, the existence of the Frank-Starling mechanism, and an increase in mean velocity (and therefore in cardiac output) after conversion of fetal tachyarrhythmias to normal sinus rhythm.

Fetal cardiac arrhythmias.

Fetal cardiac arrhythmias have been classified and the current literature reviewed. Emphasis is placed on antepartum diagnosis and appropriate therapy. The incidence of congenital heart disease varies with the type of arrhythmia. The differential diagnosis of fetal cardiac arrhythmias and management are discussed.

SEM-dissection of a human embryo derived from an ectopic pregnancy.

A 6.5-week-old human embryo with an approximate crown-rump length of 13.2 mm was obtained from a tubal pregnancy. Two hours before surgical removal, the embryo was imaged with real time ultrasound and was noted to have rhythmic cardiac motion. Subsequent to surgical removal, the embryo was dissected free from the placenta and prepared for routine scanning electron microscopic (SEM) studies. Progressive stages of dissection with microsurgical instruments followed by SEM photography elucidated the three-dimensional aspects of embryonic development of many structures, including the lens placode, tongue bud, Rathke's pouch, atrial and ventricular foramina, primitive intestinal loop and undifferentiated external genitalia. Almost certainly, such clear views of dissected structures can contribute to our understanding of human embryonic development.

Embryonic heart rates before the seventh week of pregnancy.

Previous studies of normal human embryonic heart rates showed an increase in the rates between the 7th and 9th gestational weeks; the rates gradually declined thereafter until the 15th week. The present study added new information about embryonic heart rates before the seventh week. The heart rates are slower than those reported to occur after the seventh week. These observations are connected with morphologic and physiologic changes during this period of embryonic life.

Bicornuate uterus with incomplete vaginal septum and unilateral renal agenesis. Ultrasound demonstration in two patients.

Ultrasound studies in two patients revealed identical anomalies consisting of unilateral renal agenesis, bicornuate uterus, communication between the two uterine cavities at a level just above the cervix, and incomplete vaginal septum with a blind hemivagina filled with purulent material. One patient was 28 weeks pregnant at the time of diagnosis and was managed surgically.