Cardiopulmonary Baroreflex Control of Renal Sympathetic Nerve Activity Is Impaired in Dogs With Left Ventricular Dysfunction.

BACKGROUND: Activation of neurohormonal systems contributes to the progression of heart failure (HF). The mechanism(s) whereby these systems become activated is(are) not fully explained. We determined whether vagal cardiopulmonary baroreflex control of renal sympathetic nerve activity is abnormal in dogs with left ventricular (LV) dysfunction in the absence of clinical HF, and the relationship of abnormalities in baroreflexes to the development of the neurohumoral excitatory state. METHODS: LV end-systolic and end-diastolic dimensions (echocardiography), arterial baroreflex sensitivity (slope of ΔRR/Δsystolic BP during phenylephrine or nitroglycerin bolus), and neurohumoral profiles (plasma norepinephrine, renin activity, and arginine vasopressin) were measured serially in conscious dogs (n=24) with progressive LV dysfunction due to rapid ventricular pacing. LV dimensions were used to define groups with mild, moderate, and marked LV dilatation (LVD; increase in LV end-diastolic volume <15%, 15-30%, and >30% of control, respectively). Changes in renal nerve activity (RNA) were recorded in response to increases in pulmonary capillary wedge pressure (PCWP) induced by volume infusion in anesthetized, sinoaortic-denervated dogs. RESULTS: Cardiopulmonary baroreflex sensitivity (slope of %ΔRNA/ΔPCWP) for mild LVD (-17.8%/mmHg) was the same as controls (-17.7%/mmHg). However, the slopes of moderate (-5.8%/mmHg) and severe LVD (-1.9%/mmHg) were decreased significantly compared with controls (P < .05). Arterial baroreflex sensitivity was preserved at all stages of LVD. Plasma norepinephrine, renin activity, and arginine vasopressin remained unchanged after 4, 7, and 11 days of pacing. CONCLUSIONS: Vagal cardiopulmonary baroreflex control of renal sympathetic nerve activity is blunted early in the development of LVD. These abnormalities precede neurohumoral excitation and abnormal arterial baroreflexes and become apparent when LV end-diastolic volume starts to increase.

Effects of Xanthine Oxidase Inhibition in Hyperuricemic Heart Failure Patients: The Xanthine Oxidase Inhibition for Hyperuricemic Heart Failure Patients (EXACT-HF) Study.

BACKGROUND: Oxidative stress may contribute to heart failure (HF) progression. Inhibiting xanthine oxidase in hyperuricemic HF patients may improve outcomes. METHODS AND RESULTS: We randomly assigned 253 patients with symptomatic HF, left ventricular ejection fraction ≤40%, and serum uric acid levels ≥9.5 mg/dL to receive allopurinol (target dose, 600 mg daily) or placebo in a double-blind, multicenter trial. The primary composite end point at 24 weeks was based on survival, worsening HF, and patient global assessment. Secondary end points included change in quality of life, submaximal exercise capacity, and left ventricular ejection fraction. Uric acid levels were significantly reduced with allopurinol in comparison with placebo (treatment difference, -4.2 [-4.9, -3.5] mg/dL and -3.5 [-4.2, -2.7] mg/dL at 12 and 24 weeks, respectively, both P<0.0001). At 24 weeks, there was no significant difference in clinical status between the allopurinol- and placebo-treated patients (worsened 45% versus 46%, unchanged 42% versus 34%, improved 13% versus 19%, respectively; P=0.68). At 12 and 24 weeks, there was no significant difference in change in Kansas City Cardiomyopathy Questionnaire scores or 6-minute walk distances between the 2 groups. At 24 weeks, left ventricular ejection fraction did not change in either group or between groups. Rash occurred more frequently with allopurinol (10% versus 2%, P=0.01), but there was no difference in serious adverse event rates between the groups (20% versus 15%, P=0.36). CONCLUSIONS: In high-risk HF patients with reduced ejection fraction and elevated uric acid levels, xanthine oxidase inhibition with allopurinol failed to improve clinical status, exercise capacity, quality of life, or left ventricular ejection fraction at 24 weeks. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00987415.

Clinical and Research Considerations for Patients With Hypertensive Acute Heart Failure: A Consensus Statement from the Society of Academic Emergency Medicine and the Heart Failure Society of America Acute Heart Failure Working Group.

Management approaches for patients in the emergency department (ED) who present with acute heart failure (AHF) have largely focused on intravenous diuretics. Yet, the primary pathophysiologic derangement underlying AHF in many patients is not solely volume overload. Patients with hypertensive AHF (H-AHF) represent a clinical phenotype with distinct pathophysiologic mechanisms that result in elevated ventricular filling pressures. To optimize treatment response and minimize adverse events in this subgroup, we propose that clinical management be tailored to a conceptual model of disease based on these mechanisms. This consensus statement reviews the relevant pathophysiology, clinical characteristics, approach to therapy, and considerations for clinical trials in ED patients with H-AHF.

Interactive effects of hypoxia, hypercapnia and lung volume on sympathetic nerve activity in humans.

NEW FINDINGS: What is the central question of this study? The central question of this study was to investigate the interaction of mild exposures to O2 and CO2 on chemoreflex control of SNA and the modulation of lung volume and respiratory phase on this interaction. What is the main finding and its importance? We demonstrate that the synergistic interaction of oxygen- and carbon dioxide-chemosensitive control of the sympathetic nervous system with hypoxia and hypercapnia exists at very mild excitatory stimuli, is significantly overridden by lung inflation and does not extend to inhibitory modulation by hypocapnia in healthy subjects. These findings demonstrate the important inhibitory modulation of sympathetic nerve activity by lung inflation mechanisms in healthy individuals even in the presence of strong sympathoexcitatory stimuli. We hypothesized that simultaneous stimulation of O2 - and CO2 -sensitive chemoreflexes produces synergistic activation of the sympathetic nervous system and that this effect would be most apparent at low lung volume (expiratory) phases of respiration. Each subject (n = 11) breathed 16 gas mixtures in random order: a 4 × 4 matrix of normoxic to hypoxic (8, 12, 16 and 21% O2 ) combined with normocapnic to hypercapnic gases (0, 2, 4 and 6% CO2). Tidal volume, arterial pressure, heart rate and muscle sympathetic nerve activity (MSNA) were measured continuously before and while breathing each gas mixture for 2 min. Changes in MSNA were determined for each gas mixture. The MSNA was subdivided into low and high lung volume and respiratory phases to investigate further modulation by components of normal respiratory phase. Both hypoxia and hypercapnia increased mean MSNA independently. Mean and low lung volume MSNA increased exponentially with increasing levels of combined hypoxia and hypercapnia and resulted in a significant interaction (P < 0.01). In contrast, MSNA during the high lung volume phase of respiration never increased significantly (P > 0.4). Similar but less pronounced effects were found for expiratory and inspiratory phases of respiration. These effects created marked respiratory periodicity in MSNA at higher levels of combined hypoxia and hypercapnia. Finally, the response to hypoxia was not affected by hypocapnia, suggesting that the interaction occurs only during excitatory chemosensitive stimuli. These data indicate that hypoxia and hypercapnia interact to elicit synergistic sympathoexcitation and that withdrawal of sympathoinhibitory effects of lung inflation exaggerates this chemoreflex interaction.

Autonomic Modulation in Heart Failure: Ready for Prime Time?

It has been known for many decades that multiple abnormalities of the autonomic nervous system (ANS) are present in heart failure (HF). Moreover, many of the effective therapies currently used to treat HF have either direct or indirect effects on the ANS. While therapies that block over-activity of the sympathetic nervous system are now standard of care, much less well studied are therapies aimed at augmenting the parasympathetic nervous system. This review will cover recent and ongoing investigations targeting modulation of the ANS, especially highlighting new and ongoing studies directed toward augmenting parasympathetic mechanisms.

Adherence to clinical guidelines in heart failure (HF) outpatients: Impact of an interprofessional HF team on evidence-based medication use.

Clinical systolic heart failure (HF) guidelines specify recommendations for ACE inhibitors (ACEI), angiotensin receptor blockers (ARB), and beta blockers according to doses used in clinical trials. However, many HF patients remain suboptimally treated. We sought to determine which provider type, between an interprofessional HF team, non-HF cardiologists, and primary care physicians (PCP), most optimally manages HF medications and doses. A retrospective chart review was performed on adult patients at an academic county hospital with an ejection fraction ≤40% and a diagnosis of HF, seen by a single provider type (HF team, cardiologist, or PCP) at least twice within a 12-month period. Utilization rates of any ACEI/ARB and any beta blocker were robust across provider types, though evidence-based ACEI/ARB and beta blocker were greatest from the HF team. Doses of evidence-based therapies dropped markedly in the non-HF team groups. The percent of patients prescribed optimal doses of an evidence-based ACEI/ARB AND beta blocker was 69%, 33%, and 25% for the HF team, cardiologists and PCPs, respectively (p < 0.0167). Patients followed by the HF team were more frequently prescribed evidence-based medications at optimal doses. This supports using specialized interprofessional HF teams to attain greater adherence to evidence-based recommendations in treating systolic HF.

Early pandemic in-hospital outcomes and mortality risk factors in COVID-19 solid organ transplant patients.

Background: Solid organ transplant (SOT) recipients with COVID-19 have a higher risk of mortality than those without COVID-19. However, it is unclear how SOT patient outcomes compare to the general population without SOT who contract COVID-19. Methods: We used the National Inpatient Sample from January to December 2020 to investigate inpatient outcomes seen in SOT recipients after contracting COVID-19 compared to nontransplant patients. We identified our study sample using ICD-10 CM and excluded those <18 years of age and those with dual organ transplants. Inpatient outcomes were compared in SOT and non-SOT COVID cohorts, and we further evaluated predictors of mortality in the SOT with COVID population. Results: Out of the 1,416,445 COVID-19 admissions included in the study, 8315 (0.59%) were single SOT recipients. Our analysis that adjusted for multiple baseline characteristics and comorbidities demonstrated that COVID-19 in SOT patients was associated with higher rates of acute kidney injury (adjusted odds ratio [aOR] 2.34, 95% confidence interval [CI] 1.81-3.02, P < 0.01), lower rates of acute respiratory distress syndrome (aOR 0.68, 95% CI 0.54-0.85, P < 0.01), and similar rates of cardiac arrest, pulmonary embolism, circulatory shock, cerebrovascular events, and in-hospital mortality. Age >65 was associated with mortality in SOT patients. Conclusion: In this nationally representative sample, SOT patients presenting with COVID-19 experienced similar rates of mortality compared to those without SOT. SOT patients were more likely to develop acute kidney injury. Further research is needed to understand the complex relationship between transplant patient outcomes and COVID-19.

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. The trial was carried out at 49 hospitals in nine countries. Sleep-disordered breathing was stratified into predominantly OSA with an Epworth Sleepiness Scale score of 10 or lower or predominantly CSA. Participants were randomly assigned to standard optimal treatment alone or standard optimal treatment with the addition of ASV (1:1), stratified by study site and sleep apnoea type (ie, CSA or OSA), with permuted blocks of sizes 4 and 6 in random order. Clinical evaluations were performed and Minnesota Living with Heart Failure Questionnaire, Epworth Sleepiness Scale, and New York Heart Association class were assessed at months 1, 3, and 6 following randomisation and every 6 months thereafter to a maximum of 5 years. The primary endpoint was the cumulative incidence of the composite of all-cause mortality, first admission to hospital for a cardiovascular reason, new onset atrial fibrillation or flutter, and delivery of an appropriate cardioverter-defibrillator shock. All-cause mortality was a secondary endpoint. Analysis for the primary outcome was done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT01128816) and the International Standard Randomised Controlled Trial Number Register (ISRCTN67500535), and the trial is complete. FINDINGS: The first and last enrolments were Sept 22, 2010, and March 20, 2021. Enrolments terminated prematurely due to COVID-19-related restrictions. 1127 patients were screened, of whom 731 (65%) patients were randomly assigned to receive standard care (n=375; mean AHI 42·8 events per h of sleep [SD 20·9]) or standard care plus ASV (n=356; 43·3 events per h of sleep [20·5]). Follow-up of all patients ended at the latest on June 15, 2021, when the trial was terminated prematurely due to a recall of the ASV device due to potential disintegration of the motor sound-abatement material. Over the course of the trial, 41 (6%) of participants withdrew consent and 34 (5%) were lost to follow-up. In the ASV group, the mean AHI decreased to 2·8-3·7 events per h over the course of the trial, with associated improvements in sleep quality assessed 1 month following randomisation. Over a mean follow-up period of 3·6 years (SD 1·6), ASV had no effect on the primary composite outcome (180 events in the control group vs 166 in the ASV group; hazard ratio [HR] 0·95, 95% CI 0·77-1·18; p=0·67) or the secondary endpoint of all-cause mortality (88 deaths in the control group vs. 76 in the ASV group; 0·89, 0·66-1·21; p=0·47). For patients with OSA, the HR for all-cause mortality was 1·00 (0·68-1·46; p=0·98) and for CSA was 0·74 (0·44-1·23; p=0·25). No safety issue related to ASV use was identified. INTERPRETATION: In patients with heart failure and reduced ejection fraction and sleep-disordered breathing, ASV had no effect on the primary composite outcome or mortality but eliminated sleep-disordered breathing safely. FUNDING: Canadian Institutes of Health Research and Philips RS North America.

Chemohypersensitivity and autonomic modulation of venous capacitance in the pathophysiology of acute decompensated heart failure.

Heart failure is increasing in prevalence around the world, with hospitalization and re-hospitalization as a result of acute decompensated heart failure (ADHF) presenting a huge social and economic burden. The mechanism for this decompensation is not clear. Whilst in some cases it is due to volume expansion, over half of patients with an acute admission for ADHF did not experience an increase in total body weight. This calls into question the current treatment strategy of targeting salt and water retention in ADHF. An alternative hypothesis proposed by Fallick et al. is that an endogenous fluid shift from the splanchnic bed is implicated in ADHF, rather than an exogenous fluid gain. The hypothesis states further that this shift is triggered by an increase in sympathetic tone causing vasoconstriction in the splanchnic bed, a mechanism that can translocate blood rapidly into the effective circulating volume, generating the raised venous pressure and congestion seen in ADHF. This hypothesis encourages a new clinical paradigm which focuses on the underlying mechanisms of congestion, and highlights the importance of fluid redistribution and neurohormonal activation in its pathophysiology. In this article, we consider the concept that ADHF is attributable to episodic sympathetic hyperactivity, resulting in fluid shifts from the splanchnic bed. Chemosensitivity is a pathologic autonomic mechanism associated with mortality in patients with systolic heart failure. Tonic and episodic activity of the peripheral chemoreceptors may underlie the syndrome of acute decompensation without total body salt and water expansion. We suggest in this manuscript that chemosensitivity in response to intermittent hypoxia, such as experienced in sleep disordered breathing, may explain the intermittent sympathetic hyperactivity underlying renal sodium retention and acute volume redistribution from venous storage sites. This hypothesis provides an alternative structure to guide novel diagnostic and treatment strategies for ADHF.

Anemia and iron deficiency in heart failure.

Anemia is a common comorbidity in heart failure (HF), and is associated with increased morbidity and mortality. However, it remains unclear whether anemia is merely a marker of poor prognosis or whether anemia itself confers risk. The pathogenesis of anemia in HF is multifactorial. Iron deficiency also confers risk in HF, either with or without associated anemia, and treatment of iron deficiency improves the functional status of patients with HF. An ongoing large clinical trial studying the use of darbepoetin-alfa in patients with anemia and systolic HF is expected to provide information that should improve our understanding of anemia in HF.

Evidence for impaired vagus nerve activity in heart failure.

Parasympathetic control of the heart via the vagus nerve is the primary mechanism that regulates beat-to-beat control of heart rate. Additionally, the vagus nerve exerts significant effects at the AV node, as well as effects on both atrial and ventricular myocardium. Vagal control is abnormal in heart failure, occurring at early stages of left ventricular dysfunction, and this reduced vagal function is associated with worse outcomes in patients following myocardial infarction and with heart failure. While central control mechanisms are abnormal, one of the primary sites of attenuated vagal control is at the level of the parasympathetic ganglion. It remains to be seen whether or not preventing or treating abnormal vagal control of the heart improves prognosis.

Extracardiac Abnormalities of Preload Reserve: Mechanisms Underlying Exercise Limitation in Heart Failure with Preserved Ejection Fraction, Autonomic Dysfunction, and Liver Disease.

While many of the cardiac limitations to exercise performance are now well-characterized, extracardiac limitations to exercise performance have been less well recognized but are nevertheless important. We propose that abnormalities of cardiac preload reserve represents an under-recognized but common cause of exercise limitations. We further propose that mechanistic links exist between conditions as seemingly disparate as heart failure with preserved ejection fraction, nonalcoholic fatty liver disease, and pelvic venous compression/obstruction syndromes (eg, May-Thurner). We conclude that extracardiac abnormalities of preload reserve serve as a major pathophysiologic mechanism underlying these and other disease states.

Splanchnic nerve modulation in heart failure: mechanistic overview, initial clinical experience, and safety considerations.

Volume recruitment from the splanchnic compartment is an important physiological response to stressors such as physical activity and blood loss. In the setting of heart failure (HF), excess fluid redistribution from this compartment leads to increased cardiac filling pressures with limitation in exercise capacity. Recent evidence suggests that blocking neural activity of the greater splanchnic nerve (GSN) could have significant benefits in some patients with HF by reducing cardiac filling pressures and improving exercise capacity. However, to date the long-term safety of splanchnic nerve modulation (SNM) in the setting of HF is unknown. SNM is currently used in clinical practice to alleviate some forms of chronic abdominal pain. A systematic review of the series where permanent SNM was used as a treatment for chronic abdominal pain indicates that permanent SNM is well tolerated, with side-effects limited to transient diarrhoea or abdominal colic and transient hypotension. The pathophysiological role of the GSN in volume redistribution, the encouraging findings of acute and chronic pilot SNM studies and the safety profile from permanent SNM for pain provides a strong basis for continued efforts to study this therapeutic target in HF.

The heart failure clinic: a consensus statement of the Heart Failure Society of America.

BACKGROUND: Outpatient care accounts for a significant proportion of total heart failure (HF) expenditures. This observation, plus an expanding list of treatment options, has led to the development of the disease-specific HF clinic. METHODS AND RESULTS: The goals of the HF clinic are to reduce mortality and rehospitalization rates and improve quality of life for patients with HF through individualized patient care. A variety of staffing configurations can serve to meet these goals. Successful HF clinics require an ongoing commitment of resources, the application of established clinical practice guidelines, an appropriate infrastructure, and a culture of quality assessment. CONCLUSIONS: This consensus statement will identify the components of HF clinics, focusing on systems and procedures most likely to contribute to the consistent application of guidelines and, consequently, optimal patient care. The domains addressed are: disease management, functional assessment, quality of life assessment, medical therapy and drug evaluation, device evaluation, nutritional assessment, follow-up, advance planning, communication, provider education, and quality assessment.

Characterization of health-related quality of life in heart failure patients with preserved versus low ejection fraction in CHARM.

BACKGROUND: Limited comparative studies assessing the health-related quality of life (HRQL) in heart failure (HF) patients with preserved vs. low ejection fraction (LVEF) have been disparate. AIMS: The aims of this study were a) to characterize HRQL in a large population of HF patients with preserved and low LVEF and b) to determine the factors associated with worse HRQL. METHODS: Patients with symptomatic HF (NYHA Class II-IV) enrolled in the Candesartan in Heart Failure: Assessment of Reduction in Mortality and Morbidity (CHARM) HRQL study completed the Minnesota Living with Heart Failure questionnaire at randomization. Patients were stratified into 2 HF cohorts: preserved LVEF (>40%) and low LVEF (

Augmentation index and central aortic stiffness in middle-aged to elderly individuals.

BACKGROUND: Increased aortic stiffness contributes to systolic hypertension and increased cardiovascular risk. The augmentation index (AI), ie, the percentage of central pulse pressure attributed to reflected wave overlap in systole, was proposed as a noninvasive indicator of increased arterial stiffness. We evaluated this hypothesis by investigating relations between AI and other direct measures of aortic stiffness. METHODS: Tonometric carotid- and femoral-pressure waveforms, Doppler aortic flow, and aortic-root diameter were assessed in 123 individuals with uncomplicated systolic hypertension and 29 controls of comparable age and sex. Carotid-femoral pulse-wave velocity (PWV) was assessed from the carotid-femoral time delay and body-surface measurements. Aortic PWV was assessed from the ratio of the upstroke of carotid pressure and aortic flow velocity and was used to calculate proximal aortic compliance as [aortic area]/[1.06 x (aortic PWV)(2)]. RESULTS: Partial correlations (adjusted for age, sex, presence of hypertension, height, weight, and systolic ejection period) showed no association between AI and carotid-femoral PWV (R = -0.05, P = .54). The AI was significantly though weakly related directly with aortic compliance (R = 0.21, P = .012) and inversely with aortic PWV (R = -0.198, P = .017). However, higher stiffness (lower compliance and higher PWV) was associated with lower AI. CONCLUSIONS: Increased AI is not a reliable surrogate for increased aortic stiffness. Decreasing AI with decreasing compliance (increasing aortic stiffness) may be attributable to impedance matching and reduced wave reflection at the interface between the aorta and the muscular arteries.