Kathryn L. Reed

CARDIAC DOPPLER FLOW VELOCITIES IN HUMAN FETUSES

Cardiac Doppler flow velocity studies were performed in normal human fetuses between 18 and 40 weeks of gestation. Two-dimensional linear array and sector scanning techniques were used for the initial evaluation of the fetuses, which included a standard ultrasound examination to determine normal anatomy and estimated gestational age and weight. Fetal cardiac ultrasound examination was then performed, with four-chamber, short-axis/great vessel, long-axis/left ventricular outflow tract, and aortic arch views obtained. Pulsed echo Doppler instrumentation was used to obtain flow velocity measurements through the tricuspid, pulmonary outflow, mitral, and aortic outflow regions. Calculation of transvalve volume flow for mitral and tricuspid valves was performed by combining the valve anulus sizes and calculated mean temporal velocities for the valves. Maximal flow velocities were greater through the tricuspid (mean maximal velocity 51 +/- 1.2 [SE] cm/sec) than through the mitral (47 +/- 1.1 cm/sec; p less than .05) valve regions, with a wide range of scatter for results between fetuses but less than 6% average variation in the individual fetuses during gestation. For 18 fetuses, right heart dimensions and volume flows (mean 307 + 30 ml/kg/min) were greater than left heart dimensions and volume flows (232 +/- 25 ml/kg/min). Doppler echocardiography may prove to be useful as an adjunct to imaging echocardiography for evaluation of fetal cardiac anatomy and function.

Tricuspid valve disease with significant tricuspid insufficiency in the fetus: Diagnosis and outcome

The echocardiographic studies and clinical course of 27 fetuses (mean gestational age 26.9 weeks) diagnosed in utero with tricuspid valve disease and significant tricuspid regurgitation were reviewed. The diagnosis of Ebsteins anomaly was made in 17 of the fetuses, 7 had tricuspid valve dysplasia with poorly developed but normally attached leaflets and 2 had an unguarded tricuspid valve orifice with little or no identifiable tricuspid tissue. One fetus was excluded from data analysis because a more complex heart lesion was documented at autopsy. All fetuses had massive right atrial dilation and most who were serially studied had progressive right-sided cardiomegaly. Hydrops fetalis was found in six cases and atrial flutter in five. Associated cardiac lesions included pulmonary stenosis in five cases and pulmonary atresia in six. Four fetuses with normal forward pulmonary artery flow at the initial examination were found at subsequent study to have retrograde pulmonary artery and ductal flow in association with the development of pulmonary stenosis (n = 1) and pulmonary atresia (n = 3). On review of the clinical course of the 23 fetuses (excluding 3 with elective abortion), 48% of the fetuses died in utero and 35% who were liveborn died despite vigorous medical and, when necessary, surgical management, many of whom had severe congestive heart failure. Of the four infants who survived the neonatal period, three had a benign neonatal course, all of whom were diagnosed with mild to moderate Ebsteins anomaly; only one had pulmonary outflow obstruction. An additional finding at autopsy was significant lung hypoplasia documented in 10 of 19 autopsy reports.(ABSTRACT TRUNCATED AT 250 WORDS)

Gender differences in academic advancement: Patterns, causes, and potential solutions in one U.S. College of Medicine

Purpose The influx of women into academic medicine has not been accompanied by equality for male and female faculty. Women earn less than men in comparable positions, progress more slowly through academic ranks, and have not attained important leadership roles. This study tested hypotheses about why gender disparities exist in salary, rank, track, leadership, and perceptions of campus climate at one academic center, the University of Arizona College of Medicine, Tucson. Method Salary, rank, and track data were obtained from institutional databases for the 1999–2000 fiscal year. A structured, online questionnaire was made available to 418 faculty members to collect information about their goals, attitudes, and experiences. Results A total of 198 faculty members completed the questionnaire. The data showed significant gender differences in faculty salaries, ranks, tracks, leadership positions, resources, and perceptions of academic climate. On average, women earned

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

12,777 or 11% less than men, after adjusting for rank, track, degree, specialty, years in rank, and administrative positions (p < .0003). Of female faculty, 62% were assistant professors (49% of women were non–tenure-eligible assistant professors), while 55% of male faculty were promoted and tenured. Almost a third of women reported being discriminated against, compared with only 5% of men (p < .00001). Conclusion Substantial gender differences in the rewards and opportunities of academic medicine remain, that can not be attributed to differences in productivity or committment between women and men.

Changes in intracardiac Doppler blood flow velocities in fetuses with absent umbilical artery diastolic flow

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)

The dimension of chaos in the fetal heart rate

Umbilical artery Doppler blood flow velocity studies were used to identify 14 fetuses with absent flow during diastole to determine the significance of absent umbilical artery diastolic flow. Outcomes of these fetuses were recorded, and the associated intracardiac Doppler changes were identified in 12 of them. Maximal and mean intracardiac flow velocities were measured, and volume flows through the right (tricuspid valve, pulmonary valve) and left (mitral valve, aortic valve) sides of the heart were compared. Ratios of intracardiac peak flow velocity in late diastole to peak flow velocity in early diastole were calculated. Eleven fetuses had intrauterine growth retardation, and four had multiple congenital anomalies. Fetuses with no diastolic flow in the umbilical artery had increased volume flow across the tricuspid and pulmonary valves compared with normal fetuses of similar weights. The ratio of right-sided to left-sided volume flow in the heart (2.15:1) was increased compared with values in normal fetuses (1.33:1, p less than 0.01). The ratio of late diastolic to early diastolic peak flow velocities across the mitral valve was decreased (p less than 0.01). Absent umbilical artery diastolic flow is associated with increased tricuspid and pulmonary valve volume flow and changes in mitral flow velocity patterns, which suggests that there are alterations in left ventricular function.

Prenatal ultrasound diagnosis of hypoplastic left heart syndrome in utero associated with hydrops fetalis

Variability in the fetal heart rate is known to be a sign of fetal well-being, and yet the origins of the variations remain unclear. This study incorporated the nonlinear analytic techniques of phase-space reconstruction and dimensional analysis to 12 normal heart rate tracings obtained from fetal scalp electrodes of fetuses in labor. Phase-space attractors were constructed with the method of time delays and showed characteristics consistent with those of nonlinear chaotic systems. Dimensional analysis resulted in three distinct groups being identified. Results indicate that control of the fetal heart rate may be modeled as a nonlinear or chaotic system, and analytic techniques borrowed from the physical sciences are useful in exploring heart rate variability. That different groups could be distinguished among qualitatively similar heart rate tracings may lead to understanding of discrepancies between evaluation of the monitor tracing and neonatal outcome.

Adolescence and very low birth weight infants: A disproportionate association

Abstract Ultrasound is widely used in obstetrics as a screening technique for fetal size and maturity, placental structure and function, and for detection of fetal congenital malformations in complicated pregnancies. 1–3 Our own work on qualitative and quantitative fetal echocardiography 4,5 and the work of others 6 has suggested that high resolution ultrasound can be used to assess fetal heart rhythm and function, and can detect congenital heart malformations before birth. In this report, we delineate prenatal diagnosis of hypoplastic left heart syndrome in a fetus with signs of hydrops fetalis, who was found after cesarean section to have associated trisomy 13. Additionally, we diagnosed the ususual occurrence of an intraventricular thrombus within the hypoplastic left ventricular cavity. The fetal ultrasound evaluation was of major importance in the perinatal management of both mother and unborn child.

Doppler echocardiographic observations of pulmonary and transvalvular velocity changes after birth and during the early neonatal period.

Objective To examine the incidence of very low birth weight (VLBW) neonates, defined as those weighing less than 1500 g, delivered by adolescents compared with the general obstetric population. Methods A retrospective observational study of 16,857 women delivering live-born infants from January 1,1989, to June 30, 1993, was conducted at the University of Arizona Health Sciences Center. Adolescents were defined as those having a maternal age of 18 years or less at the time of delivery. The rate of VLBW infants delivered to adolescent mothers was compared with the general obstetric population (women at least 19 years old) using χ2 analysis, multiple analysis of variance, and multiple linear regression. Results During the study period, 204 VLBW infants were delivered, yielding an overall VLBW delivery rate of 1.2%. Adolescents had a VLBW delivery rate that was considerably higher than the general obstetrical population: 35 of 1758 (2.0%) versus 169 of 15,099 (1.1%) (P = .002). Whereas adolescents accounted for 10.6% of the total deliveries during the study period, they delivered 17% of the VLBW neonates. The relative risk of an adolescent delivering a VLBW infant was 1.7 (95% confidence interval 1.2-2.2). Conclusion Preterm birth is one of the major unresolved problems in modern obstetrics. Although the association between adolescence and preterm birth has been reported previously, specific attention has not been focused on the VLBW neonate. We conclude that adolescents deliver a disproportionate number of VLBW infants.

Significance of oligohydramnios complicating pregnancy

To evaluate the qualitative and quantitative changes in Doppler velocities in the normal fetus and newborn, 61 echo Doppler studies were performed in 18 neonates, nine of whom were also studied as fetuses. Four studies were inadequate in fetuses (one pulmonary artery, two mitral, and one tricuspid) and some post natal studies were inadequate due to inability to separate atrioventricular valve E and A velocity component waveforms (one tricuspid, three mitral). Heart rates for fetuses and newborns more than 24 hours of age and less than 24 hours of age were similar. Pulmonary artery diastolic velocities consistent with patent ductus arteriosus were present in 11 of 12 examinations at less than 6 hours of age, in 5 of 13 examined at 6 to 24 hours of age, and in 2 of 27 examined after 24 hours of age. Pulmonary artery times to peak velocity were similar in fetuses, m = 46, SD = 3 msec, and in neonates less than 6 hours of age, m = 51, SD = 13 msec, but lengthened significantly, p less than 0.05, at 6 to 24 hours (m = 69, SD = 14 msec). These changes are probably due to the dramatic changes in pulmonary vascular pressure that occur after birth. Data from 6 to 24 hours and greater than 24 hours (m = 78, SD = 13 msec) were similar. Significant differences existed for transmitral valve E/A ratios, which increased from m = 0.85 in utero to m = 1.17 (p less than 0.05) after birth, with no significant change thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)