Elevated blood pressure is one of the main risk factors for death globally. Behavioral neurocardi... more Elevated blood pressure is one of the main risk factors for death globally. Behavioral neurocardiac training (BNT) is a complementary approach to blood pressure and stress management that is intended to exercise the autonomic reflexes, improve stress recovery, and lower blood pressure. BNT involves cognitive-behavioral therapy with a paced breathing technique and heart rate variability biofeedback. BNT is limited to in-clinic delivery and faces an accessibility barrier because of the need for clinical oversight and the use of complex monitoring tools. The objective of this project was to design, develop, and evaluate a wearable electrocardiographic (ECG) sensor system for the delivery of BNT in a home setting. The wearable sensor system, Beat, consists of an ECG sensor and a mobile app. It was developed iteratively using the principles of test-driven Agile development and user-centered design. A usability study was conducted at Toronto General Hospital to evaluate feasibility and us...
We evaluated the influence of psychological stress and depression on motivation to adhere to reco... more We evaluated the influence of psychological stress and depression on motivation to adhere to recommended guidelines for exercise and diet. This study was conducted within a larger e-counseling trial. Subjects diagnosed with hypertension (n=387, age = 44–74 years, 59% female) completed assessments at baseline and within 2 weeks after a 4-month intervention period. Outcomes included mean level of readiness to change diet and exercise and symptoms of depression and stress. Per protocol analysis defined e-counseling support as follows: ≥8 e-mails = therapeutic dose, 1–7 e-mails = subtherapeutic dose, and 0 e-mails = Controls. Baseline adjusted symptoms of depression and stress were inversely correlated with improvement in exercise (partialR=-.14,P=.01, and partialR=-.17,P=.01, resp.) but not diet or e-counseling. Subjects who received a therapeutic dose of e-counseling demonstrated greater readiness for diet adherence versus Controls (P=.02). Similarly, subjects receiving a therapeutic ...
Systemic inflammation is associated with sympathetic cardiac activation and decreased HRV (heart ... more Systemic inflammation is associated with sympathetic cardiac activation and decreased HRV (heart rate variability) in subjects at high risk of CAD (coronary artery disease). In the present study, we examined the influence of systemic inflammation, measured by CRP (C-reactive protein), on vagal HR (heart rate) control during behavioural relaxation in patients with CAD. It was hypothesized that CRP would be associated with decreased vagal HR modulation. Consecutive patients were screened 2 weeks prior to elective PTCA (percutaneous transluminal coronary angioplasty). The study was comprised of 29 subjects who represented the first and fourth quartiles of the CRP distribution: Low (0.47±0.07 μg/ml)- and High (8.19±1.95 μg/ml)-CRP groups respectively. Vagal HR control was quantified as RR high-frequency spectral power (0.15 to 0.40 Hz), and was assessed in log-transformed absolute units (logHF power). Near-IR particle immunoassay was used to determine high-sensitivity CRP concentration....
Background: Elevated blood pressure is a leading risk factor for cardiovascular disease and morta... more Background: Elevated blood pressure is a leading risk factor for cardiovascular disease and mortality. Internet-based interventions (ecounselling) have the potential to deliver a wide range of preventive counselling services. The purpose of this review was to (1) assess the efficacy of e-counselling in reducing blood pressure and (2) identify key components of successful trials in order to highlight factors that may contribute significantly to blood pressure control.
Web-based lifestyle counselling designed to improve adherence to self-management behaviours for d... more 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). 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 a...
Elevated blood pressure is one of the main risk factors for death globally. Behavioral neurocardi... more Elevated blood pressure is one of the main risk factors for death globally. Behavioral neurocardiac training (BNT) is a complementary approach to blood pressure and stress management that is intended to exercise the autonomic reflexes, improve stress recovery, and lower blood pressure. BNT involves cognitive-behavioral therapy with a paced breathing technique and heart rate variability biofeedback. BNT is limited to in-clinic delivery and faces an accessibility barrier because of the need for clinical oversight and the use of complex monitoring tools. The objective of this project was to design, develop, and evaluate a wearable electrocardiographic (ECG) sensor system for the delivery of BNT in a home setting. The wearable sensor system, Beat, consists of an ECG sensor and a mobile app. It was developed iteratively using the principles of test-driven Agile development and user-centered design. A usability study was conducted at Toronto General Hospital to evaluate feasibility and us...
We evaluated the influence of psychological stress and depression on motivation to adhere to reco... more We evaluated the influence of psychological stress and depression on motivation to adhere to recommended guidelines for exercise and diet. This study was conducted within a larger e-counseling trial. Subjects diagnosed with hypertension (n=387, age = 44–74 years, 59% female) completed assessments at baseline and within 2 weeks after a 4-month intervention period. Outcomes included mean level of readiness to change diet and exercise and symptoms of depression and stress. Per protocol analysis defined e-counseling support as follows: ≥8 e-mails = therapeutic dose, 1–7 e-mails = subtherapeutic dose, and 0 e-mails = Controls. Baseline adjusted symptoms of depression and stress were inversely correlated with improvement in exercise (partialR=-.14,P=.01, and partialR=-.17,P=.01, resp.) but not diet or e-counseling. Subjects who received a therapeutic dose of e-counseling demonstrated greater readiness for diet adherence versus Controls (P=.02). Similarly, subjects receiving a therapeutic ...
Systemic inflammation is associated with sympathetic cardiac activation and decreased HRV (heart ... more Systemic inflammation is associated with sympathetic cardiac activation and decreased HRV (heart rate variability) in subjects at high risk of CAD (coronary artery disease). In the present study, we examined the influence of systemic inflammation, measured by CRP (C-reactive protein), on vagal HR (heart rate) control during behavioural relaxation in patients with CAD. It was hypothesized that CRP would be associated with decreased vagal HR modulation. Consecutive patients were screened 2 weeks prior to elective PTCA (percutaneous transluminal coronary angioplasty). The study was comprised of 29 subjects who represented the first and fourth quartiles of the CRP distribution: Low (0.47±0.07 μg/ml)- and High (8.19±1.95 μg/ml)-CRP groups respectively. Vagal HR control was quantified as RR high-frequency spectral power (0.15 to 0.40 Hz), and was assessed in log-transformed absolute units (logHF power). Near-IR particle immunoassay was used to determine high-sensitivity CRP concentration....
Background: Elevated blood pressure is a leading risk factor for cardiovascular disease and morta... more Background: Elevated blood pressure is a leading risk factor for cardiovascular disease and mortality. Internet-based interventions (ecounselling) have the potential to deliver a wide range of preventive counselling services. The purpose of this review was to (1) assess the efficacy of e-counselling in reducing blood pressure and (2) identify key components of successful trials in order to highlight factors that may contribute significantly to blood pressure control.
Web-based lifestyle counselling designed to improve adherence to self-management behaviours for d... more 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). 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 a...
The incidence of coronary heart disease (CHD) and the distribution of contributory risk factors a... more The incidence of coronary heart disease (CHD) and the distribution of contributory risk factors are closely linked with social patterns of advantage and disadvantage. The authors conducted eight focus groups in urban, northern, and rural sites in Ontario, Canada. Participants were all at high absolute risk for or had been diagnosed with CHD. Analysis centered on habitus, which forms the pivotal link between the person and "place." The authors focused on participants' dialogue about stress because it dealt with the impingements of the social world and resultant constraints on health-related activities in everyday places. Participants described four types of places or social positions in their "stress talk": work-places, transitional spaces, gendered situations, and exclusions. Places can support or constrain health related activities in many ways. Habits and practices linked with stress by participants were enduringly associated with these contexts, suggesting...
We appreciate the Editorial Comment by Dr. R. P. Sloan [1] on our recent proof of principle study... more We appreciate the Editorial Comment by Dr. R. P. Sloan [1] on our recent proof of principle study [2] of the cholinergic anti-inflammatory reflex. Nevertheless, we are concerned that four points of criticism raised in the Comment [1] signify inaccurate reading of our text. This obliges a response, if only to facilitate a clear and parsimonious reading of our paper. To continue with the Buffalo Springfield metaphor (to ‘For What It’s Worth’*) entitling Dr. Sloan’s Comment [1], we invite readers to focus on this song’s refrain as they consider our reported results and to simply look what’s going down amongst measures of inflammation when markers of vagal heart rate modulation increase over time.
It is not established whether behavioral interventions add benefit to pharmacological therapy for... more It is not established whether behavioral interventions add benefit to pharmacological therapy for hypertension. We hypothesized that behavioral neurocardiac training (BNT) with heart rate variability biofeedback would reduce blood pressure further by modifying vagal heart rate modulation during reactivity and recovery from standardized cognitive tasks (“mental stress”). This randomized, controlled trial enrolled 65 patients with uncomplicated hypertension to BNT or active control (autogenic relaxation), with six 1-hour sessions over 2 months with home practice. Outcomes were analyzed with linear mixed models that adjusted for antihypertensive drugs. BNT reduced daytime and 24-hour systolic blood pressures (−2.4±0.9 mm Hg, P =0.009, and −2.1±0.9 mm Hg, P =0.03, respectively) and pulse pressures (−1.7±0.6 mm Hg, P =0.004, and −1.4±0.6 mm Hg, P =0.02, respectively). No effect was observed for controls ( P >0.10 for all indices). BNT also increased RR-high-frequency power (0.15 to 0....
European Journal of Cardiovascular Prevention & Rehabilitation, 2008
Heart rate variability (HRV) is reported as a surrogate index for clinical outcome in trials of s... more Heart rate variability (HRV) is reported as a surrogate index for clinical outcome in trials of secondary prevention strategies for coronary artery disease (CAD), but a standardized guide for interpreting HRV change is not established. We evaluated HRV change in trials with CAD patients who received conventional medications (beta-blockers, calcium channel blockers, angiotensin converting enzyme inhibitors), biobehavioral treatment (psychotropics, biofeedback, relaxation) or exercise training. Medline, Pubmed, Psycinfo, the Cochrane database, and Embase were searched until July 2007, without language restriction. We identified 33 randomized controlled trials. Two reviewers independently abstracted all trials using a standardized form. A hierarchy of frequency and time domain HRV indices defined outcome. A random-effects model yielded an overall pooled standardized mean difference (SMD) between treatment and control groups of moderate magnitude across treatment classes, based on a composite of time and frequency domain indices (SMD=0.40, P<0.0001), or only time or frequency indices (SMD=0.37 and 0.43, respectively, both P<0.0001). This change was equivalent to an increase in standard deviation of all normal-to-normal RR intervals of 9.0 ms (95% Confidence Interval, CI, 7.3, 10.7 ms) or a relative increase of 15.9% (95% CI, 13.2, 18.6%). To detect HRV change of this magnitude, a hypothetical trial would require a sample size of 660 patients for conventional medications or 1232 patients for all treatment classes. Pharmacologic, biobehavioral and exercise strategies for secondary prevention of CAD significantly increase HRV. This review provides a framework to assist efforts to evaluate the contribution of HRV change to CAD prognosis.
We examined the association between heart rate variability (HRV) and duration of type 2 diabetes ... more We examined the association between heart rate variability (HRV) and duration of type 2 diabetes among 155 female and 106 male subjects: mean±SD for duration=49.6±65.6 and 57.3±77.1 months, respectively, p=0.38. Among males, duration of diabetes was independently and inversely associated with vagal-heart rate modulation (high frequency (HF) power, 0.15—0.40 Hz, standardised ß = -0.32, p=0.001; root mean square of successive differences between R-R intervals, ß = -0.26, p=0.006) and total R-R variability (standard deviation of normal R-R intervals, ß = -0.36, p=0.001); but not among females (p≥0.80 for each HRV index). In contrast, HF was inversely associated with age of diabetes diagnosis (ß = -0.16, p=0.04) and 10-year absolute risk for coronary heart disease (ß = -0.16, p=0.04) among female subjects. Longitudinal research is needed to establish whether risk factors for early cardiac autonomic impairment differ among men and women with type 2 diabetes.
Previous research has established a relation between depression at the time of cardiac hospitaliz... more Previous research has established a relation between depression at the time of cardiac hospitalization and patient mortality. The objective of this study was to examine the role of depressive history and symptomatology during hospitalization on 5-year all-cause mortality after admission for an acute coronary syndrome. We recruited 750 patients who had unstable angina pectoris and myocardial infarction from 12 coronary care units between 1997 and 1999. Measurements included sociodemographic and clinic data and the Beck Depression Inventory (BDI). Data were linked to an administrative database to determine 5-year all-cause mortality. Survival data were adjusted using a Cox's proportional hazards model. One hundred seventy-four participants (23.2%) self-reported a history of depressed mood for >2 weeks, 235 (31.3%) had elevated BDI scores at index hospitalization, with 105 (14.0%) reporting persistent depressive symptomatology. One hundred fifteen participants (15.3%) died by 5 years after hospitalization. After adjusting for prognostic indicators, such as cardiac disease severity, medical history, and smoking, depressive symptomatology during hospitalization was significantly predictive of mortality, but depressive history was not. Hazard ratios associated with BDI scores <10 versus those > or =10 at hospitalization ranged from 1.90 (95% confidence interval 1.12 to 3.24) at 2 years to 1.53 (95% confidence interval 1.04 to 2.24) at 5 years. In conclusion, the significance of depressive symptomatology at the time of, but not before, hospitalization underlines the need for early identification of increased distress and renews calls to identify treatments that not only improve quality of life but also decrease the risk of mortality.
Preventive electronic (e)-counselling has been shown to reduce cardiovascular risk factors. Howev... more Preventive electronic (e)-counselling has been shown to reduce cardiovascular risk factors. However, heterogeneity in outcomes is commonly reported due to differences in e-protocols. We incorporated key features of an established behavioural therapy, motivational interviewing, to help standardize e-counselling in order to reduce blood pressure in patients with hypertension. Subjects (n = 387, mean age = 56 years, 59% female, 72% taking ≥ 1 antihypertensive drug) were diagnosed with stage 1 or 2 hypertension. Subjects were randomized to a 4-month protocol of e-counselling (beta version of the "Blood Pressure Action Plan", Heart and Stroke Foundation of Canada) vs waitlist control (general e-information on heart-healthy living). Outcomes were systolic, diastolic, and pulse pressures, and total lipoprotein cholesterol after treatment. Intention to treat analysis did not find a significant group difference in outcomes due to contamination across the 2 arms of this trial. However, per protocol analysis indicated that subjects receiving ≥ 8 e-counselling messages (a priori therapeutic dose) vs 0 e-counselling messages (control) demonstrated greater reduction in systolic blood pressure (mean, -8.9 mm Hg; 95% confidence interval [CI], -11.5 to -6.4 vs -5.0 mm Hg; 95% CI, -6.7 to -3.3, P = 0.03), pulse pressure (-6.1 mm Hg; 95% CI, -8.1 to -4.1 vs -3.1 mm Hg; 95% CI, -4.3 to -1.8, P = 0.02) and total cholesterol (-0.24 mmol/L; 95% CI, -0.43 to -0.06 vs 0.05 mmol/L; 95% CI, -0.06 to 0.16, P = 0.03), but not diastolic blood pressure. These findings support the merit of evaluating whether e-counselling can improve blood pressure control and reduce cardiovascular risk over the long-term.
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Heart Rate Variability by Rob Nolan
e-Counseling and Heart Health by Rob Nolan
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