Reduced brain perfusion and cognitive performance due to constitutional hypotension

Modulations of autonomic cardiovascular control following acute alpha-adrenergic treatment in chronic hypotension

“…25 However, considering the rise in RSA, it seems likely that the reduction in LF power was not due to decreased parasympathetic influences but instead due to decreased sympathetic influences in the control of heart rate. Taken together, the findings suggest that the previously described increased BRS and dominance of the parasympathetic system in cardiac regulation of chronic hypotension 5,9,16 were further augmented by drug application. Midodrine does not cross the blood-brain barrier and, therefore, does not directly influence central nervous control of the cardiovascular system.…”

“…This is, however, accompanied by strong autonomic counter-regulation in terms of a shift of sympathovagal balance toward increased parasympathetic and reduced sympathetic influences in cardiac control. This implies that the magnitude of the autonomic dysbalance, which is regarded as relevant in the etiology of chronic hypotension, 5,9 is not reduced, but actually increased. The pronounced reduction in heart rate may constitute another problem.…”

“…9 Besides aberrant baroreflex function, reduced sympathetic and increased parasympathetic influences on cardiovascular regulation have also been postulated in chronic hypotension. 5,16 Several studies have documented generally diminished sympathetic tone, 17,18 and Cadalbert 16 reported augmented respiratory sinus arrhythmia (RSA) in chronically hypotensive participants, indicating increased vagal influences on heart rate.…”

“…1,2 Reduced cognitive performance, as well as diminished cerebral blood flow and cortical activation have been documented in this condition. [3][4][5] According to the World Health Organization (WHO), 6 hypotension is to be diagnosed when systolic blood pressure falls below 100 mm Hg in women and 110 mm Hg in men. The condition of chronic ('essential') hypotension must be distinguished from secondary hypotension, caused, for example, by blood loss or medication, as well as from the orthostatic form, that is, circulatory problems when assuming an upright position.…”

“…7 It has been considered whether alterations in autonomic cardiovascular regulation are involved in the etiology of chronic hypotension. 5,8 Duschek et al 9 reported increased baroreflex sensitivity (BRS) in a hypotensive sample. The baroreflex consists of a negative feedback loop in which changes in the firing rate of the arterial baroreceptors lead to compensatory alterations in heart rate and cardiac contractility.…”