Sympathetic Response to 1-Leg Cycling Exercise Predicts Exercise Capacity in Patients With Heart Failure With Preserved Ejection Fraction.

Background: In heart failure, sympathetic excess and exercise intolerance impair quality of life. In heart failure with reduced ejection fraction, exercise stimulates a reflex increase in muscle sympathetic nerve activity (MSNA) that relates inversely to peak oxygen uptake (V̇O). Whether similar sympathoexcitatory responses are present in heart failure with preserved EF (HFpEF) and relate to V̇O are unknown.

Treating sleep disordered breathing for cardiovascular outcomes: observational and randomised trial evidence.

Sleep disordered breathing (SDB) is considered a risk factor for cardiovascular disease (CVD). Obstructive sleep apnoea (OSA) can be treated with continuous positive airway pressure (CPAP), and central sleep apnoea (CSA), in patients with heart failure with reduced ejection fraction (HFrEF), by peak flow-triggered adaptive servo-ventilation. Presently, there is equipoise as to whether treating SDB prevents cardiovascular events.

Nocturnal Cardiac Arrhythmias in Heart Failure With Obstructive and Central Sleep Apnea.

Background: Both obstructive and central sleep apnea (CSA) may contribute to nocturnal cardiac arrhythmias (NCAs). Data are scarce regarding the prevalence of clinically important nocturnal atrial and ventricular arrythmias in patients with heart failure with reduced ejection fraction (HFrEF) and OSA or CSA.

Research Question: In a cohort of patients with HFrEF, how does the prevalence of NCA compare among those with OSA, CSA, and those with no to mild sleep apnea? Is the severity of OSA or CSA associated with atrial and ventricular NCAs?

Study Design And Methods: This cross-sectional analysis is an ancillary study of the Effect of Adaptive Servo Ventilation on Survival and Hospital Admissions in Heart Failure (ADVENT-HF) trial.

Coronary and Systemic Vasodilator Responsiveness of Patients Receiving Conventional Intermittent or Nocturnal Hemodialysis.

Background: Nocturnal hemodialysis (nHD) restores the attenuated brachial artery vasodilator responsiveness of patients receiving conventional intermittent hemodialysis (iHD). Its impact on coronary vasodilatation is unknown.

Methods: We evaluated 25 patients on hemodialysis who fulfilled transplant criteria: 15 on iHD (4-hour sessions, 3 d/wk) and 10 on nHD (≈40 h/wk over 8-10-hour sessions) plus 6 control participants.

Sleep Apnea, Autonomic Disturbances, and Blood Pressure Variability.

Augmented blood pressure variability has emerged as a quantity predictive of adverse cardiovascular outcomes. Among the range of intrinsic and extrinsic factors shown to increase night-time, circadian, short-term, and long-term blood pressure variations, the presence and severity of obstructive sleep apnea have emerged as one of the most prevalent and potent. Obstructive sleep apnea alters acutely the normal nocturnal equilibrium between sympathetic and parasympathetic tone, magnifying nocturnal blood pressure oscillations, and induces sustained autonomic aftereffects with the capacity to amplify short-term and intersessional blood pressure variabilities.

Characterizing Hypertension Specialist Care in Canada: A National Survey.

Background: The hypertension specialist often receives referrals of patients with young-onset, severe, difficult-to-control hypertension, patients with hypertensive emergencies, and patients with secondary causes of hypertension. Specialist hypertension care compliments primary care for these complex patients and contributes to an overall hypertension control strategy. The objective of this study was to characterize hypertension centres and the practice patterns of Canadian hypertension specialists.

Adaptive servo-ventilation for sleep-disordered breathing in patients with heart failure with reduced ejection fraction (ADVENT-HF): a multicentre, multinational, parallel-group, open-label, phase 3 randomised controlled trial.

Background: In patients with heart failure and reduced ejection fraction, sleep-disordered breathing, comprising obstructive sleep apnoea (OSA) and central sleep apnoea (CSA), is associated with increased morbidity, mortality, and sleep disruption. We hypothesised that treating sleep-disordered breathing with a peak-flow triggered adaptive servo-ventilation (ASV) device would improve cardiovascular outcomes in patients with heart failure and reduced ejection fraction.

Methods: We conducted a multicentre, multinational, parallel-group, open-label, phase 3 randomised controlled trial of peak-flow triggered ASV in patients aged 18 years or older with heart failure and reduced ejection fraction (left ventricular ejection fraction ≤45%) who were stabilised on optimal medical therapy with co-existing sleep-disordered breathing (apnoea-hypopnoea index [AHI] ≥15 events/h of sleep), with concealed allocation and blinded outcome assessments.

Cardiovascular reflex contributions to sympathetic inhibition during low intensity dynamic leg exercise in healthy middle-age.

Aging augments resting muscle sympathetic nerve activity (MSNA) and sympatho-inhibition during mild dynamic 1-leg exercise. To elucidate which reflexes elicit exercise-induced inhibition, we recruited 19 (9 men) healthy volunteers (mean age 56 ± 9 SD years), assessed their peak oxygen uptake (VO ), and, on another day, measured heart rate (HR), blood pressure (BP) and MSNA (microneurography) at rest and during 1-leg cycling (2 min each at 0 load and 30%-40% VO ), 3 times: (1) seated +2 min of postexercise circulatory occlusion (PECO) (elicit muscle metaboreflex); (2) supine (stimulate cardiopulmonary baroreflexes);and (3) seated, breathing 32% oxygen (suppress peripheral chemoreceptor reflex). While seated, MSNA decreased similarly during mild and moderate exercise (p < 0.

Autonomic and respiratory consequences of altered chemoreflex function: clinical and therapeutic implications in cardiovascular diseases.

The importance of chemoreflex function for cardiovascular health is increasingly recognized in clinical practice. The physiological function of the chemoreflex is to constantly adjust ventilation and circulatory control to match respiratory gases to metabolism. This is achieved in a highly integrated fashion with the baroreflex and the ergoreflex.

Normal and excessive muscle sympathetic nerve activity in heart failure: implications for future trials of therapeutic autonomic modulation.

Aims: Patients with sympathetic excess are those most likely to benefit from novel interventions targeting the autonomic nervous system. To inform such personalized therapy, we identified determinants of augmented muscle sympathetic nerve activity (MSNA) in heart failure, versus healthy controls.

Methods And Results: We compared data acquired in 177 conventionally-treated, stable non-diabetic patients in sinus rhythm, aged 18-79 years (149 males; 28 females; left ventricular ejection fraction [LVEF] 25 ± 11% [mean ± standard deviation]; range 5-60%), and, concurrently, under similar conditions, in 658 healthy, normotensive volunteers (398 males; aged 18-81 years).

Muscle Sympathetic Excitatory Response to Dynamic 1-Leg Cycling in Heart Failure With Preserved Ejection Fraction.

We provide the first description in a patient with heart failure with preserved ejection fraction of the "paradoxical," exaggerated reflex increase in muscle sympathetic nerve activity in the opposite, stationary limb during dynamic 1-leg cycling exercise that was documented previously in patients with reduced ejection fraction. ().

Attenuated Sympathetic Blood Pressure Transduction in Patients With Treated Heart Failure With Reduced Ejection Fraction.

Background: Heart failure with reduced ejection fraction (HFrEF) is associated with reduced cardiac β-adrenergic signal transduction in response to chronic elevations in neurally released and circulating norepinephrine. Whether elevations in muscle sympathetic nerve activity (MSNA) are accompanied by attenuated α-adrenoceptor-mediated vasoconstriction remains unclear. Therefore, the objective of the current work was to compare transduction of sympathetic firing into blood pressure (BP) in treated patients with HFrEF and healthy controls.

Influence of sex and age on the relationship between aerobic fitness and muscle sympathetic nerve activity in healthy adults.

We examined the influence of sex and age on the relationship between aerobic fitness and muscle sympathetic nerve activity (MSNA) in healthy adults. Data were assessed from 224 volunteers (88 females), aged 18-76 yr, in whom resting MSNA (microneurography) and peak oxygen uptake (V̇o; incremental exercise test) were evaluated. When separated into younger (<50 yr) and older (≥50 yr) subgroups, there were inverse relationships between relative V̇o (mL·kg·min) and MSNA burst frequency in younger males ( = 0.

Methodology for the nocturnal cardiac arrhythmia ancillary study of the ADVENT-HF trial in patients with heart failure with reduced ejection fraction and sleep-disordered breathing.

Background: Sleep disordered breathing (SDB) may trigger nocturnal cardiac arrhythmias (NCA) in patients with heart failure with reduced ejection fraction (HFrEF). The NCA ancillary study of the ADVENT-HF trial will test whether, in HFrEF-patients with SDB, peak-flow-triggered adaptive servo-ventilation (ASVpf) reduces NCA. To this end, accurate scoring of NCA from polysomnography (PSG) is required.

Warmer summer nocturnal surface air temperatures and cardiovascular disease death risk: a population-based study.

Background: In recent summers, some populous mid-latitude to high-latitude regions have experienced greater heat intensity, more at night than by day. Such warming has been associated with increased cause-specific adult mortality. Sex-specific and age-specific associations between summer nocturnal surface air temperatures (SAT) and cardiovascular disease (CVD) deaths have yet to be established.