Kevin Shoemaker

Reducing risk with e-based support for adherence to lifestyle change in hypertension (REACH): protocol for a multicentred randomised controlled trial

Introduction Web-based lifestyle counselling designed to improve adherence to self-management behaviours for diet, exercise and medication has been shown to reduce blood pressure (BP). However, the long-term clinical outcome of these interventions is not established. Our aim was to establish whether an e-counselling program is independently associated with improved clinical outcomes over a 12-month period, as defined by the following criteria: (1) reduction of systolic BP, diastolic BP, pulse pressure and associated risk factors for cardiovascular events; and (2) adherence to self-management behaviour (diet, exercise, smoke-free living and prescribed medication). Methods and analysis Reducing risk with e-based support for adherence to lifestyle change in hypertension is a two-parallel group, double-blind randomised controlled trial that will utilise a two (Groups: e-counselling vs control) by three (assessment intervals: baseline, 4-month and 12-month outcome) design. BP, lipoprotein cholesterol, physical activity and dietary behaviours and psychological distress will be measured at each assessment. We plan to recruit 528 participants (35–74 years of age) diagnosed with stage 1 or 2 hypertension (systolic BP, 140–180 mm Hg; diastolic BP 90–110 mm Hg) from three major cities (Toronto, London, Vancouver) and one rural area (Grey Bruce region) across Canada between February 2012 and July 2015. Controls will receive general educational e-messages on heart healthy living and the e-counselling group will receive tailored e-messages that are matched to their stage of readiness for change. For both groups, e-messages will be sent proactively on a weekly basis during months 1–4, then bi-weekly during months 5–8 and then monthly during months 9–12. Ethics and dissemination Ethical approval has been obtained from all recruitment sites. This will be one of the first studies to evaluate the long-term efficacy of preventive e-counselling strategies for cardiovascular disease prevention in patients with hypertension. Findings from this study will be used to guide the ongoing development of e-counselling services. Trial Registration Clinicaltrial.gov NCT01541540; http://clinicaltrials.gov/ct2/show/NCT01541540.

Group-based exercise combined with dual-task training improves gait but not vascular health in active older adults without dementia

BACKGROUND Gait abnormalities and vascular disease risk factors are associated with cognitive impairment in aging. OBJECTIVE To determine the impact of group-based exercise and dual-task training on gait and vascular health, in active community-dwelling older adults without dementia. METHODS Participants [n=44, mean (SD) age: 73.5 (7.2) years, 68% female] were randomized to either intervention (exercise+dual-task; EDT) or control (exercise only; EO). Each week, for 26 weeks, both groups accumulated 50 or 75 min of aerobic exercise from group-based classes and 45 min of beginner-level square stepping exercise (SSE). Participants accumulating only 50 min of aerobic exercise were instructed to participate in an additional 25 min each week outside of class. The EDT group also answered cognitively challenging questions while performing SSE (i.e., dual-task training). The effect of the interventions on gait and vascular health was compared between groups using linear mixed effects models. RESULTS At 26 weeks, the EDT group demonstrated increased dual-task (DT) gait velocity [difference between groups in mean change from baseline (95% CI): 0.29 m/s (0.16-0.43), p<0.001], DT step length [5.72 cm (2.19-9.24), p =0.002], and carotid intima-media thickness [0.10mm (0.003-0.20), p=0.04], as well as reduced DT stride time variability [8.31 coefficient of variation percentage points (-12.92 to -3.70), p<0.001], when compared to the EO group. CONCLUSIONS Group-based exercise combined with dual-task training can improve DT gait characteristics in active older adults without dementia.

Innovation to Reduce Cardiovascular Complications of Diabetes at the Intersection of Discovery, Prevention and Knowledge Exchange

This article describes selected primary outcomes from a series of linked, collaborative projects among multidisciplinary investigators from Canada and Finland dedicated to quantifying the benefits and detriments of prescriptive exercise in the prevention and control of the cardiovascular complications (CVCs) of diabetes along the continuum of disease risk.

Temporal artery Doppler spectrum morphology responses to tilt and LBNP as an early indicator of syncope.

OBJECTIVE In a study to identify an early hemodynamic predictor of syncope, 12 men (25-40 yr) underwent 30 min of 80 degrees head-up tilt, followed by progressive lower body negative pressure (LBNP) until presyncope. METHODS Temporal (supplying extracranial tissues: TEMP), middle cerebral (MCA), and superficial femoral (FEM) arterial flow velocity (V) and vascular resistance indices (VR) were evaluated continuously using Doppler ultrasound. Ratios of the Doppler V(MEAN) (V(MCA)/V(FEM) or V(MCA)/ V(TEMP)) were used to assess flow redistribution between these areas. RESULTS The progression of the testing protocol showed increases in vascular resistance in all territories. At presyncope, both MCA(VR) and FEM(VR) were reduced while there was a large increase in TEMP(VR). Vasoconstriction of the vascular bed supplied by the temporal artery occurred early during central hypovolemia resulting in the appearance of negative velocity deflections, which could be used for the early detection of impending syncope. Analysis of the velocity ratios showed little change until the onset of presyncope where there was an increase in V(MCA)/V(TEMP) which confirmed that vasoconstriction of the vascular bed supplied by the TEMP artery contributed to cardiac output redistribution in favor of the brain, and a reduction in V(MCA)/V(FEM) suggesting a redistribution of cardiac output toward the legs. DISCUSSION In 67% of the tests, the appearance of the negative component of V(TEMP) was an early sign of increasing TEMP(VR) that occurred before visually detectable changes in VE(FEM) or V(MCA) and within 5 min before presyncope. Such easily identifiable in real time Doppler signs allowed experimenters to anticipate test termination.

System identification of baroreflex response to mild lower body negative pressure

The effect of mild lower body negative pressure (LBNP) on baroreflex control of arterial blood pressure (ABP) has long been thought to affect cardiopulmonary baroreflex only, although recent studies have pointed out that arterial baroreceptors may be transiently unloaded too after the rapid onset of mild LBNP. This paper presents a spectral decomposition method for the black box identification of the contribution of arterial and cardiopulmonary baroreflexes to beat-by-beat variability of ABP in response to mild LBNP levels. The significant decrease of mean and diastolic arterial pressure and of the arterial baroreflex mediated contribution to overall variability of ABP which was found, suggested that the unloading of arterial baroreceptors may be reflected by an altered dynamic response of arterial baroreflex, too. In addition, arterial baroreflex mediated modulations were found to be the main player in the modulation of beat-by-beat fluctuations of ABP, while the role of cardiopulmonary baroreflex mediated responses appeared to contribute very little.

FEEDBACK EFFECTS OF CIRCULATING NOREPINEPHRINE ON SYMPATHETIC OUTFLOW

The amplitude of low-frequency (LF) oscillations of heart rate (HR) usually reflects the magnitude of sympathetic activity, but during some conditions, e.g., physical exercise, high sympathetic activity results in a paradoxical decrease of LF oscillations of HR. We tested the hypothesis that this phenomenon may result from a feedback inhibition of sympathetic outflow caused by circulating norepinephrine (NE). A physiological dose of NE (100 ng.kg(-1).min(-1)) was infused into eight healthy subjects, and infusion was continued after alpha-adrenergic blockade [with phentolamine (Phe)]. Muscle sympathetic nervous activity (MSNA) from the peroneal nerve, LF (0.04-0.15 Hz) and high frequency (HF; 0.15-0.40 Hz) spectral components of HR variability, and systolic blood pressure variability were analyzed at baseline, during NE infusion, and during NE infusion after Phe administration. The NE infusion increased the mean blood pressure and decreased the average HR (P < 0.01 for both). MSNA (10 +/- 2 vs. 2 +/- 1 bursts/min, P < 0.01), LF oscillations of HR (43 +/- 13 vs. 35 +/- 13 normalized units, P < 0.05), and systolic blood pressure (3.1 +/- 2.3 vs. 2.0 +/- 1.1 mmHg2, P < 0.05) decreased significantly during the NE infusion. During the NE infusion after PHE, average HR and mean blood pressure returned to baseline levels. However, MSNA (4 +/- 2 bursts/min), LF power of HR (33 +/- 9 normalized units), and systolic blood pressure variability (1.7 +/- 1.1 mmHg2) remained significantly (P < 0.05 for all) below baseline values. Baroreflex gain did not change significantly during the interventions. Elevated levels of circulating NE cause a feedback inhibition on sympathetic outflow in healthy subjects. These inhibitory effects do not seem to be mediated by pressor effects on the baroreflex loop but perhaps by a presynaptic autoregulatory feedback mechanism or some other mechanism that is not prevented by a nonselective alpha-adrenergic blockade.