Attenuation of baroreflex sensitivity and heart rate variability is linked to reduced levels of nitric oxide in pregnant women having risks of developing gestational hypertension

Abstract

Purpose: Decreased baroreflex sensitivity (BRS) and sympathovagal imbalance (SVI) have been reported as a cardiovascular (CV) risk in gestational hypertension (GH). Nitric oxide (NO) has been implicated in pathophysiology of GH. In the present study, we assessed the link of CV risks (decreased BRS and SVI) to the plasma levels of NO in women having risk of developing GH. Materials and Methods: A total of 96 pregnant women having risk factors for GH were recruited for the study. The blood pressure variability (BPV), heart rate variability (HRV), plasma NO, marker of insulin resistance (HOMA-IR), lipid risk factors, inflammatory markers (hsCRP, interleukin-6), and malondialdehyde (MDA), the marker of oxidative stress (OS) were measured at 16^th and 36^th week. Link of various parameters to NO was assessed by correlation and multiple regression analysis. Results: Of HRV indices, parasympathetic components were decreased and sympathetic components were increased, BRS was decreased, NO was decreased, HOMA-IR, lipid risk factors, hsCRP, interleukin-6, and MDA were increased significantly at 36^th week compared to 16^th week of pregnancy. Most of the markers of cardiometabolic risk were correlated with NO. However, only the markers of CV risk (SVI and reduced BRS) were independently associated with decreased level of NO, but not the metabolic markers except interleukin-6. The independent contribution of BRS (β = 0.334, P < .001) to NO was found to be most significant. Conclusion: It was concluded that decreased BRS, SVI, and increased interleukin-6 are associated with reduction in NO in GH, which may possibly be linked to the development of CV risks in GH.

Keywords: Gestational hypertension; cardiovascular risk; interleukin-6; nitric oxide; sympathovagal imbalance.