Age-related effects of vagotonic atropine on cardiovagal baroreflex gain

Blood Pressure Variability and Ocular Vestibular-Evoked Myogenic Potentials Are Independently Associated With Orthostatic Hypotension

BACKGROUND AND PURPOSE

We delineated the association between otolithic dysfunction and blood pressure (BP) variability.

METHODS

We prospectively recruited 145 consecutive patients (age=71 [59-79] years, median [interquartile range]; 76 females) with orthostatic intolerance between December 2021 and December 2023 at a tertiary hospital in South Korea. Each patient underwent evaluations of cervical and ocular vestibular-evoked myogenic potentials (oVEMPs), 24-h noninvasive ambulatory BP monitoring (ABPM), and a head-up tilt-table test using the Finometer device. As measures of BP variability, the standard deviations (SDs) of the systolic BP (SBPSD) and the diastolic BP were calculated based on serial ABPM recordings. Patients were divided into those with orthostatic hypotension (OH, n=68) and those with a normal head-up tilt-table test despite orthostatic intolerance (NOI, n=77) groups.

RESULTS

A multivariable logistic regression analysis showed that OH was associated with bilateral oVEMP abnormalities (p=0.021), SBPSD (p=0.012), and female sex (p=0.004). SBPSD was higher in patients with OH than in those with NOI (p<0.001), and was not correlated with n1-p1 amplitude (p=0.491) or normalized p13-n23 amplitude (p=0.193) in patients with OH. The sensitivity and specificity for differentiating OH from NOI were 72.1% and 67.5%, respectively, at a cutoff value of 12.7 mm Hg for SBPSD, with an area under the receiver operating characteristic curve of 0.73.

CONCLUSIONS

Bilaterally deficient oVEMP responses may be associated with OH regardless of 24-h BP variability, reflecting the integrity of the otolith-autonomic reflex during orthostasis. Alternatively, 24-h BP variability is predominantly regulated by the baroreflex, which also participates in securing orthostatic tolerance complementary to the vestibulo-autonomic reflex.

Orthostatic hypotension in older people: considerations, diagnosis and management

Orthostatic hypotension (OH) is very common in older people and is encountered daily in emergency departments and medical admissions units. It is associated with a higher risk of falls, fractures, dementia and death, so prompt recognition and treatment are essential. In this review article, we describe the physiology of standing (orthostasis) and the pathophysiology of orthostatic hypotension. We focus particularly on aspects pertinent to older people. We review the evidence and consensus management guidelines for all aspects of management. We also tackle the challenge of concomitant orthostatic hypotension and supine hypertension, providing a treatment overview as well as practical suggestions for management. In summary, orthostatic hypotension (and associated supine hypertension) are common, dangerous and disabling, but adherence to simple structures management strategies can result in major improvements.

Effect of inspiratory muscle training with load compared with sham training on blood pressure in individuals with hypertension: study protocol of a double-blind randomized clinical trial

Background

Hypertension is a complex chronic condition characterized by elevated arterial blood pressure. Management of hypertension includes non-pharmacologic strategies, which may include techniques that effectively reduce autonomic sympathetic activity. Respiratory exercises improve autonomic control over cardiovascular system and attenuate muscle metaboreflex. Because of these effects, respiratory exercises may be useful to lower blood pressure in subjects with hypertension.

Methods/design

This randomized, double-blind clinical trial will test the efficacy of inspiratory muscle training in reducing blood pressure in adults with essential hypertension. Subjects are randomly allocated to intervention or control groups. Intervention consists of inspiratory muscle training loaded with 40 % of maximum inspiratory pressure, readjusted weekly. Control sham intervention consists of unloaded exercises. Systolic and diastolic blood pressures are co-primary endpoint measures assessed with 24 h ambulatory blood pressure monitoring. Secondary outcome measures include cardiovascular autonomic control, inspiratory muscle metaboreflex, cardiopulmonary capacity, and inspiratory muscle strength and endurance.

Discussion

Previously published work suggests that inspiratory muscle training reduces blood pressure in persons with hypertension, but the effectiveness of this intervention is yet to be established. We propose an adequately sized randomized clinical trial to test this hypothesis rigorously. If an effect is found, this study will allow for the investigation of putative mechanisms to mediate this effect, including autonomic cardiovascular control and metaboreflex.

Trial registration

ClinicalTrials.gov NCT02275377. Registered on 30 September 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1514-y) contains supplementary material, which is available to authorized users.

Chronographic Imprint of Age-Induced Alterations in Heart Rate Dynamical Organization

Beat-to-beat changes in the heart period are transformed into a network of increments between subsequent RR-intervals, which enables graphical descriptions of short-term heart period variability. Three types of such descriptions are considered: (1) network graphs arising from a set of vertices and directed edges, (2) contour plots of adjacency matrices A, representing the networks and transition matrices T, resulting from A, and (3) vector plots of gradients of the matrices A and T. Two indices are considered which summarize properties of A and T: the approximate deceleration capacity and the entropy rate. The method, applied to time series of nocturnal RR-intervals recorded from healthy subjects of different ages, reveals important aspect of changes in the autonomic activity caused by biological aging. Independent of the subject’s age, following accelerations, a pendulum-like dynamics appears. With decelerations, this dynamics develops in line with the subject’s age. This aging transition can be graphically visualized by vectors connecting the maxima of the transition probabilities of T, which, metaphorically, resemble a chronometer or the hands of a clock.