Nils-Olov Lunell

Blood pressure and renal function seven years after pregnancy complicated by hypertension

Objective To assess the occurrence of chronic hypertension and renal disorder after gestations complicated by pregnancy induced hypertension or pre‐eclampsia and to define background factors and laboratory analyses at follow up examination which discriminate between women who remain normotensive and those who develop hypertension.

Uteroplacental Blood Flow in Pre-Eclampsia Measurements with Indium-113M and a Computer-Linked Gamma Camera

Uteroplacental blood flow was measured with a computer-linked gamma camera after intravenous injection of 1 mCi indium-113m. Results of the measurements from 32 pre-eclamptic pregnancies and 37 normal controls are compared. The uteroplacental blood flow was measured as an index calculated from the rise time and maximum activity of the isotope accumulation curve. The uteroplacental blood flow was reduced with 50% in pre-eclampsia. In severe pre-eclampsia it was more compromised than in mild pre-eclampsia. A diminished uteroplacental blood flow was found in pre-eclampsia even in the absence of intrauterine growth retardation. The maternal placental circulation in the supine position was reduced with one third compared to that in the left lateral recumbent position.

Uteroplacental blood flow in diabetic pregnancy: Measurements with indium 113m and a computer-linked gamma camera

The uteroplacental blood flow index in the last trimester of pregnancy in 26 women with diabetes mellitus was compared to that in 41 healthy control subjects. After an intravenous injection of 1 mCi of indium 113m, the radiation over the placenta was recorded with a computer-linked gamma camera. From time-activity analysis of the isotope accumulation curve, a uteroplacental blood flow index could be calculated. In the diabetic pregnant women, the maternal-placental blood flow index was reduced 35% to 45% compared to that in healthy women. The blood flow index tended to be further impaired in those diabetic women who had higher blood glucose values.

Uteroplacental blood flow index in intrauterine growth retardation of fetal or maternal origin

Summary. Uteroplacental blood flow index was determined in 30 women with intrauterine growth retardation (IUGR group) and in 26 women without fetal growth retardation (control group) during the last trimester of pregnancy. After 1 mCi (37 MBq) of indium‐113m chloride had been injected intravenously the radiation was registered by a computer‐linked scintillation camera positioned above the placenta during 10 s‐intervals for 240 s. From the isotope accumulation curve a Uteroplacental blood flow index could be calculated for each patient. The median blood flow index in the IUGR group was less than half of that in the control group. In the IUGR group the index was as low in the six women who gave birth to infants with congenital malformations as in the other 24 women in whom fetal growth retardation was due to maternal factors.

Effects of nitroglycerin on the uterine and umbilical circulation in severe preeclampsia

Objective To determine the effects of nitroglycerin on placental circulation in severe preeclampsia. Methods Twelve women with severe preeclampsia were examined. Uterine and umbilical artery pulsatility indices (PI) were assessed by pulsed Doppler ultrasound before and after infusion of nitroglycerin, starting at 0.25 μg/kg per minute with stepwise dosage increases until a diastolic blood pressure (BP) of 100 mmHg was achieved. Blood pressure and heart rate were recorded every 5 minutes. Blood was sampled for analysis of the second messenger of nitric oxide, cyclic guanosine monophosphate (cGMP), before and at the end of the infusion. Results During the infusion, the mean systolic BP de-creased from 161 (95% confidence interval [CI] 154–169) to 138 mmHg (95% CI 131–146), and the diastolic pressure decreased from 116 (95% CI 111–122) to 103 (95% Cl 96–110) mmHg (P < .01). The PI of the uterine artery did not change significantly (1.23 [95% CI 1.01–1.61]) versus 1.30 [95% CI 1.01–1.88]), whereas umbilical artery PI decreased significantly (P < .01), from 1.35 (95% CI 1.09–1.73) to 1.20 (95% CI 1.05–1.40), with a more pronounced decrease in patients with high basal values. Cyclic GMP remained essentially unchanged (6.4 [95% CI 5.4–7.71 versus 5.5 [4.7–6.6] nmol/L). Conclusion The reduction in the PI of the umbilical artery during nitroglycerin-induced BP reduction implies vasodilation in the umbilical circulation. The absence of an increase in cGMP does not support the view that the nitroglycerin effect is reflected by the plasma concentration of cGMP.

Comparison of Uteroplacental Blood Flow in Normal and in Intrauterine Growth-Retarded Pregnancy

Uteroplacental blood flow was studied with a noninvasive method using indium-113m and a computer-linked gammacamera. The blood flow was determined from the ratio of the maximum and the rise time of the isotope accumulation curve of the placenta. Eight pregnancies with intrauterine growth retardation (IUGR) were compared with 11 normal pregnancies. In the IUGR group the mean placental blood flow was only 1/4 of corresponding mean values of the normal group. The difference was highly significant (p less than 0.01).

Sympatho-adrenal and cardiovascular reactivity in pregnancy-induced hypertension. I. Responses to isometric exercise and a cold pressor test

Summary. Sympatho‐adrenal and cardiovascular reactivity was studied in patients with pregnancy‐induced hypertension (PIH) and healthy pregnant controls subjected to an isometric handgrip test and a cold pressor test both during and after the pregnancy. At rest, heart rate was higher in the PIH group than in the control group both during and after pregnancy. Forearm vascular resistance was not affected by PIH or by pregnancy per se. During pregnancy arterial plasma adrenaline levels were suppressed in the control group both when compared with the PIH group and postpartum values. Arterial noradrenaline levels were similar and normal in the two groups at both examinations. The iso‐metric exercise increased systolic and diastolic blood pressures, heart rate and noradrenaline and reduced vascular resistance similarly in the PIH and control groups on both occasions. Vasoconstrictor responses to the cold pressor test were reduced during prenancy but there were no differences between the groups on either occasion. Noradrenaline responses to the cold pressor test were not influenced by PIH or by pregnancy per se. During pregnancy adrenaline responses to the two tests tended to be reduced in the controls but not in PIH. Our results indicate enhanced adrenomedullary activity in PIH when compared with the suppressed activity in normal pregnancy. Cardiovascular reactivity to the tests was similar in the PIH and control groups. The normal arterial noradrenaline levels at rest and during provocation do not support the contention of a generalized increase in sympathetic nerve activity in PIH

Acute effect of an antihypertensive drug, labetalol, on uteroplacental blood flow

Summary. The effect of a new antihypertensive drug, labetalol, on uteroplacental blood flow was determined in eight pre‐eclamptic women. After injection of 0.5 mCi of 113mIn the radioactivity in the placenta was recorded by a gamma camera linked to a computer and the placental blood‐flow index was calculated from the ratio between the maximum radioactivity of the isotope‐accumulation curve and the rise time of the curve. Labetalol, a combined α‐ and β‐adrenoceptor antagonist was given intravenously and after 30 min a second uteroplacental blood‐flow index was calculated. There was a significant mean decrease of blood pressure from 147/98 to 128/83 mmHg, but no change in uteroplacental blood‐flow index, so that uteroplacental vascular resistance tended to decrease.

Calcium channel blockade (isradipine) in treatment of hypertension in pregnancy: a randomized placebo-controlled study

OBJECTIVE Our purpose was to study the effects of isradipine, a dihydropyridine calcium channel blocker, on mother and fetus in the treatment of hypertensive disorders of pregnancy. STUDY DESIGN The investigation was performed as a two-group, parallel, double-blind multicenter study of isradipine versus placebo. Fifty-four women were randomized to treatment with isradipine slow-release capsules given orally 5 mg twice a day and 57 to a placebo group. RESULTS Isradipine lowered the maternal mean arterial blood pressure effectively in women with nonproteinuric hypertension but did not do so in women with proteinuria at recruitment or appearing during treatment. Blood flow in the umbilical artery and maternal renal and liver function were not influenced by treatment. Isradipine had few side effects and was well tolerated. CONCLUSION Calcium channel blockade with isradipine is effective for treatment of nonproteinuric hypertension but not in preeclampsia.

Maternal and fetal levels of a novel polypeptide, endothelin : evidence for release during pregnancy and delivery

The occurrence of endothelin (ET), a recently discovered polypeptide with potent vasoconstrictor properties, was studied in maternal and umbilical blood and amniotic fluid. The level of ET-like immunoreactivity (ET-LI) in maternal plasma was in most cases below the detection limit of the radioimunoassay, i.e. less than 2 pmol/l. The median concentration of ET-LI in the umbilical artery and vein before the initiation of breathing was 14.9 and 10.9 pmol/l, respectively. When sampling was performed after fetal breathing had begun, the arterial concentration increased to 93.7 pmol/l. Labor was not associated with increased concentrations of ET-LI, however, since neonates delivered by elective cesarean section had similar ET-LI in blood and amniotic fluid as after vaginal delivery. An approximately fivefold increase in the amniotic fluid ET-LI was seen at term as compared to early mid-trimester values. Reversed phase HPLC characterization revealed that the observed ET-LI mainly corresponded to ET-1. It is suggested that ET-1 may contribute to the fetal hemodynamic changes, e.g., closure of the umbilical vessels occurring at delivery.