The effect of a nitric oxide donor on fetal heart rate patterns in patients with hypertension

OBJECTIVE: To estimate whether nitric oxide donors can be administered safely to patients with pregnancy-associated hypertension based on computer analysis of antepartum fetal heart rate (FHR) tracings. METHODS: Thirty-minute recordings of FHR and fetal movements, before (stage I) and after (stage II) sublingual administration of 5 mg of isosorbide dinitrate, a nitric oxide donor, were obtained in 20 women with pregnancy-associated hypertension. RESULTS: Baseline FHR in stage I did not differ significantly from that in stage II (140.9 +/- 2.0 beats per minute and 137.5 +/- 2.1 beats per minute, respectively). There were no significant differences between stage I and II in the number (9.67 +/- 1.14 versus 9.56 +/- 1.07), amplitude (26.14 +/- 1.03 versus 24.5 +/- 0.85 beats per minute), and duration (36.03 +/- 1.46 versus 34.04 +/- 1.57 seconds) of heart rate accelerations. During stage II, the number (1.39 +/- 0.43) and duration (26.9 +/- 1.38 seconds) of heart rate decelerations did not change significantly as compared with stage I (1.67 +/- 0.33 and 26.23 +/- 1.13 seconds, respectively). However, the amplitude of heart rate decelerations was significantly higher in stage I compared with stage II (-19.36 +/- 1.44 versus -14.38 +/- 1.55 beats per minute, respectively). There were more fetal body movements during stage II than stage I (12.39 +/- 2.8 versus 9.72 +/- 2.0), but the difference was not statistically significant. CONCLUSION: Based on numeric analysis of FHR records, our data suggest that short-acting donors of nitric oxide can be administered safely to patients with pregnancy-associated hypertension.