Faculty Bibliography

Objective: Tn order to determine if tocolytic agents affect fetal ventricular function, we used the combined ventricular shortening fraction, an echocardiographic index of fetal cardiac function to evaluate fetuses whose mothers were being treated for preterm labor. Study design: A group of 30 patients diagnosed with preterm labor and eligible for tocolytic therapy were the subjects of this prospective non-randomized cohort study. Sixteen patients were treated initially with subcutaneous terbutaline, five with intravenous ritodrine, and nine with intravenous magnesium sulfate. All were later maintained on oral therapy with either terbutaline or ritodrine. Each fetus acted as its own control. Each was studied before treatment, while on a clinically therapeutic intravenous or subcutaneous regimen, during oral therapy, and after birth. The in utero evaluations included a biophysical profile, umbilical artery Doppler waveform study, and an M-mode tracing of ventricular wall motion generated from a four-chamber view of the heart to assess the end diastolic and the end systolic dimensions. The combined ventricular shortening fraction was then calculated as (end diastolic - end systolic)/end diastolic x 100%. Multiple analysis of variance was used to compare means over time for each variable. Means between groups were compared using the two-tailed Student's t test; P = 0.05 was utilized. Results: No significant change was noted in the mean combined ventricular shortening fraction of fetuses who had been exposed to tocolytic agents, all of whom had normal studies. The mean combined ventricular shortening fraction pretreatment was 34.8%, as compared with 33.9% in patients treated with beta-mimetics. Those treated with MgSO4 had an improved mean combined ventricular shortening fraction of 37.9%. This change was not statistically significant. Doppler and biophysical profiles were normal, and preterm labor was successfully arrested in all cases. Conclusion: In this small pilot study short ten treatment with commonly utilized tocolytic agents did not appear to affect fetal ventricular function

BACKGROUND: Fetal bradycardia is a common complication of funipuncture. We present a case of fetal exsanguination in which fetal tachycardia was the sole fetal heart rate abnormality. CASE: Funipuncture was performed at 32 weeks' gestation for evaluation of Rh isoimmunization. A persistent fetal tachycardia ensued and, although there was no immediate ultrasound evidence of bleeding, repeat ultrasonography revealed active bleeding at the puncture site. A neonate with an initial hematocrit of 42% was delivered by cesarean. Despite aggressive replacement of blood products, a repeat hematocrit was only 35% and a severe, persistent coagulopathy ensued. The newborn died 18 hours after delivery. Autopsy findings were consistent with neonatal coagulopathy. CONCLUSION: Although fetal bleeding is usually a common, relatively benign complication of funipuncture, streaming may not always be detected on ultrasonographic examination. Our case demonstrates that fetal tachycardia may be the only sign of fetal hemorrhage

OBJECTIVE: Nitric oxide, a potent vasodilator released by endothelial cells, inhibits platelet aggregation and adhesion to vascular endothelial surfaces. Because endothelial cell damage is considered pivotal in the pathogenesis of preeclampsia, this study was initiated to determine whether nitric oxide production is decreased in patients with preeclampsia. STUDY DESIGN: Twenty-six patients with preeclampsia (as defined by a blood pressure > or = 140 mm Hg systolic or 90 mm Hg diastolic plus proteinuria, > or = 300 mg per 24 hours or > or = 2+ by dipstick, both occurring on two occasions > or = 4 hours apart) and 26 normotensive women with singleton gestations in the third trimester were studied. Because nitric oxide is spontaneously oxidized to both nitrite and nitrate, two analytic assays were used serially. Serum nitrite levels were initially determined with the Greiss reagent and subsequently analyzed with Escherichia coli nitrate reductase. RESULTS: With the Greiss reagent alone the mean +/- SEM of serum nitrite level in 26 patients with preeclampsia was significantly decreased compared with 26 normotensive patients (3.46 +/- 1.43 mumol/L vs 4.65 +/- 0.85 mumol/L, p = 0.02). With the addition of the nitrate reductase enzyme of Escherichia coli the mean +/- SEM of serum nitrite level in 26 preeclamptic patients was again significantly decreased compared with 26 normotensive patients (20.04 +/- 1.25 mumol/L vs 27.38 +/- 2.23 mumol/L, p = 0.02). One patient with the syndrome of hemolysis, elevated liver enzymes, and low platelets demonstrated a concurrent decrease in serum nitrite over a 2-week period, emphasizing the relationship of nitric oxide to the pathophysiologic features of the syndrome. CONCLUSIONS: Circulating levels of nitrite are decreased in patients with preeclampsia. These data support the concept that diminished nitric oxide synthesis contributes to the pathophysiologic changes seen in preeclampsia

The beta-sympathomimetic oral tocolytic ritodrine can cause maternal tachycardia and hypotension, and may cross the placenta. A new echocardiographic technique has been developed to explore fetal and placental ritodrine effects. Values in 76 healthy historic controls were compared to 18 studies in 16 patients performed while receiving stable oral ritodrine therapy, measured both at baseline and 30 minutes after a dose. Data collected included maternal pulse and blood pressure (BP), fetal cerebral and umbilical Doppler waveforms, and fetal heart rate. A new index of fetal myocardial contractility, combined ventricular shortening fraction, was derived from two-dimensionally directed M-mode. Maternal pulse and BP, fetal heart rate and heart size, and all Doppler indices were normal, without demonstrable dose-response effects. In the control subjects, combined ventricular shortening fraction fell with increasing gestational age (combined ventricular shortening fraction = -0.27 estimated gestational age + 49; r = 0.27; P < or = 0.02; standard error of the estimate, 11%). However, combined ventricular shortening fraction in ritodrine patients was abnormally decreased in 72% of cases. The mean index in normal subjects was 43 +/- 5%, but in ritodrine patients it was only 31%. We conclude that a history of premature labor or oral ritodrine, or both, is associated with reduced shortening fraction. Since there was no change in placental resistance, cerebral hypoxia, fetal heart rate, or heart size (preload), then low shortening fraction may be due to increased fetal systemic vascular resistance (BP) or decreased myocardial contractility