Menstrual cycle phase does not affect sympathetic neural activity in women with postural orthostatic tachycardia syndrome

Abstract

Patients with the postural orthostatic tachycardia syndrome (POTS) are primarily premenopausal women, which may be attributed to female sex hormones. We tested the hypothesis that hormonal fluctuations of the menstrual cycle alter sympathetic neural activity and orthostatic tolerance in POTS women. Ten POTS women were studied during the early follicular (EF) and mid-luteal (ML) phases of the menstrual cycle. Haemodynamics and muscle sympathetic nerve activity (MSNA) were measured when supine, during 60 deg upright tilt for 45 min or until presyncope, and during the cold pressor test (CPT) and Valsalva manoeuvres. Blood pressure and total peripheral resistance were higher during rest and tilting in the ML than EF phase; however, heart rate, stroke volume and cardiac output were similar between phases. There were no mean ± SD differences in MSNA burst frequency (8 ± 8 EF phase vs. 10 ± 10 bursts min(-1) ML phase at rest; 34 ± 15 EF phase vs. 36 ± 16 bursts min(-1) ML phase at 5 min tilt), burst incidence or total activity, nor any differences in the cardiovagal and sympathetic baroreflex sensitivities between phases under any condition. The incidence of presyncope was also the same between phases. There were no differences in haemodynamic or sympathetic responses to CPT or Valsalva. These results suggest that the menstrual cycle does not affect sympathetic neural activity but modulates blood pressure and vasoconstriction in POTS women during tilting. Thus, factors other than sympathetic neural activity are probably responsible for the symptoms of orthostatic intolerance across the menstrual cycle in women with POTS.

Heat therapy reduces sympathetic activity and improves cardiovascular risk profile in women who are obese with polycystic ovary syndrome

“…By plotting change in diastolic pressure and burst incidence at rest compared with during Phase II nadir, a slope (⌬burst incidence/ ⌬diastolic blood pressure) was calculated as a measure of baroreflex sensitivity in response to blood pressure decrease. Although this method does not include blood pressure hysteresis, a similar technique has been used to assess sympathetic baroreflex sensitivity during Valsalva straining and matched well with measures of spontaneous baroreflex sensitivity (18,48,60).…”

Postsynaptic α 1 -Adrenergic Vasoconstriction Is Impaired in Young Patients With Vasovagal Syncope and Is Corrected by Nitric Oxide Synthase Inhibition

“…There were insufficient subjects for this purpose. However, no obvious difference in sympathetic nerve activity or vasoconstrictive ability by sex or menstrual phase has been found, although differences in total blood volume reduce blood pressure in women 48;49 .…”

Remotely Supervised Home-Based Resistance Training and Orthostatic Tolerance in Young Physically Inactive Women During COVID-19

“…Females, in general, are more likely to be diagnosed with OI than male patients (with the exception of pediatric and long-term sedentary patients) 9 . It is interesting to note that, despite higher occurrence in females, studies have failed to show any effect of menstrual cycle phase on OI in females, or on POTS 1,11 . Further, previous research suggests that women who are deconditioned are more likely to experience OI than their male counterparts 9 .…”