Objective
Most midlife women report vasomotor symptoms, yet their physiology remains poorly understood. This study tested whether acute decreases in cardiac vagal control would occur with vasomotor symptoms in a large sample of women monitored during wake and sleep.
Methods
215 nonsmoking women ages 40–60 with evidence of vasomotor symptoms were included. Women were free of a history of clinical cardiovascular disease or arrhythmia; or use of insulin, beta blockers, calcium channel blockers, or medications impacting vasomotor symptoms. Women underwent 24 hours of ambulatory monitoring for physiological (sternal skin conductance) and self-report (electronic diary) measurement of vasomotor symptoms; heart rate variability (electrocardiogram); and respiratory rate. Changes in cardiac vagal control as assessed by respiratory sinus arrhythmia during vasomotor symptoms relative to periods preceding and following vasomotor symptoms were tested in linear mixed models.
Results
Significant decreases in respiratory sinus arrhythmia were observed during physiologically-measured vasomotor symptoms relative to periods preceding (b(SE)=.13(.004), p<.0001) and following the VMS (b(SE)=.13(.004), p<.0001), adjusted for age, race, body mass index, sleep/wake. Decreases were observed for women not aware of their vasomotor symptoms, and persisted controlling for respiration rate. Interactions indicated that respiratory sinus arrhythmia decreases were most pronounced during sleep and for younger women.
Conclusions
Physiologically-measured vasomotor symptoms were accompanied by an inhibition of cardiac vagal control in a large sample of women. Changes were observed irrespective of whether the vasomotor symptoms were reported, were most pronounced during sleep, and were greatest among younger women. These findings contribute to the understanding of vasomotor symptom physiology.
