Cardiac autonomic adjustments to normal human pregnancy: Insight from spectral analysis of R-R interval and systolic arterial pressure variability

Daniela Lucini, Patrizia Strappazzon, Laura Dalla Vecchia, Cristina Maggioni, Massimo Pagani

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: To assess the adaptation in autonomic control mechanisms that accompanies the marked haemodynamic changes, such as increases in cardiac size and output, that occur in the course of normal human pregnancy. Design: We studied 14 healthy pregnant women (aged 30 ± 1 years) before the 6th week (early stage) and within weeks 32-34 (late stage) of pregnancy, while they were at rest or in a state of active orthostatism (standing), which enhances sympathetic activity. Methods: We used echocardiography to assess cardiac volumes and mass, and spectral analysis of the R-R interval and systolic arterial pressure variability to obtain indices of autonomic regulation of the circulation. This non-invasive methodology, recently validated with direct recordings of muscle sympathetic nerve activity, furnishes quantitative markers of sympathetic modulation of the sino-atrial node (low frequency component, LF in normalized units, nu), vagal modulation thigh frequency component. HF in normalized units, nu) and the overall arterial pressure-heart rate baroreflex gain (α index). Results: Late pregnancy was characterized by an increase in cardiac size and volumes and by a reduction of R-R interval, R-R interval variance and the α index, together with an increase in the LF/HF ratio (from 1.4 ± 0.4 to 5.6 ± 1.9). Changes in markers of autonomic modulation of the sino-atrial node normally induced by the standing position were blunted. Conclusions: The late stage of normal human pregnancy appears to be characterized by alterations in the autonomic control of the circulation and by attenuated responsiveness to active standing, possibly as a consequence of the accompanying increase in cardiac size. (C) Lippincott Williams and Wilkins.

Original languageEnglish
Pages (from-to)1899-1904
Number of pages6
JournalJournal of Hypertension
Volume17
Issue number12 SUPPL.
Publication statusPublished - 1999

Keywords

  • Autonomic control. echocardiography
  • Baroreflex gain
  • Cardiac output
  • Heart rate variability
  • Pregnancy
  • Spectral analysis
  • Sympathetic activity
  • Sympatho-vagal balance

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology

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