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

Catestatin as a Biomarker of Cardiovascular Diseases: A Clinical Perspective

Accounting for almost one-third of the global mortality, cardiovascular diseases (CVDs) represent a major global health issue. Emerging data suggest that most of the well-established mechanistic explanations regarding the cardiovascular pathophysiology are flawed, and cannot fully explain the progression and long-term effects of these diseases. On the other hand, dysregulation of the sympathetic nervous system (SNS) has emerged as an important player in the pathophysiology of CVDs. Even though upregulated SNS activity is an essential compensatory response to various stress conditions, in the long term, it becomes a major contributor to both cardiac dysfunction and vascular damage. Despite the fact that the importance of SNS hyperactivity in the setting of CVDs has been well-appreciated, its exact quantification and clinical application in either diagnostics or therapy of CVDs is still out of reach. Nevertheless, in recent years a number of novel laboratory biomarkers implicated in the pathophysiology of SNS activation have been explored. Specifically, in this review, we aimed to discuss the role of catestatin, a potent physiological inhibitor of catecholamine spillover that offers cardioprotective effects. Limited data indicate that catestatin could also be a reliable indirect marker of SNS activity and it is likely that high CST levels reflect advanced CV disease burden. Consequently, large-scale studies are required to validate these observations in the upcoming future.

Contributions of cardiac dysfunction and volume status to central haemodynamics in chronic heart failure

AIMS

Elevated cardiac filling pressures producing clinical congestion in heart failure (HF) patients may be secondary to intravascular volume expansion or abnormalities in cardiac diastolic properties. The objective of this study was to assess the extent to which measures of myocardial function and intravascular volume correlate with haemodynamic abnormalities in chronic HF.

METHODS AND RESULTS

Subjects underwent invasive haemodynamic assessment, measurement of total blood volume (TBV) using radiolabel indicator-dilution methodology, and echocardiography to evaluate cardiac structure and function. Patients were divided into those with hypervolaemia (defined as TBV > +8% above referenced normal volume) and normal volume ('euvolaemia') (TBV ≤ + 8%). Of 66 patients, 39 (59%) were hypervolaemic and 27 (41%) normal TBV. Central venous pressure (CVP, P = 0.01) and pulmonary capillary wedge pressure (PCWP, P < 0.001) were higher in hypervolaemic compared with euvolaemic patients; however, 15% of hypervolaemic patients displayed normal pressures. Of euvolaemic patients, 70% displayed elevated CVP and 63% elevated PCWP. PCWP was moderately correlated with TBV (r = 0.42), left ventricular diastolic function (e' velocity, r = -0.44), and left atrial strain (r = -0.47). In multivariable regression TBV, left ventricular e', and left atrial strain were independently associated with PCWP (all P < 0.05).

CONCLUSIONS

While hypervolaemic patients displayed elevations in filling pressures, a substantial proportion (15%) had normal pressures, and of all subjects with elevated filling pressures nearly one third had normal TBVs. Importantly, of patients with normal volumes, a majority (>60%) display elevated filling pressures. Combined analysis of volume, pressure, and cardiac function may be helpful to guide comprehensive assessments of HF status.

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.

Distinct clinical phenotypes of congestion in acute heart failure: characteristics, treatment response, and outcomes

Aims

Patients with acute heart failure (AHF) are included into clinical trials regardless of differences in baseline clinical characteristics. The aim of this study was to assess patients with AHF according to the presence of central and/or peripheral congestion at hospital admission and evaluate treatment response and outcomes in studied phenotypes.

Methods and results

We investigated retrospectively 352 patients (mean age: 68 ± 13 years, 77% men) hospitalized due to AHF with the signs of congestion on admission. Patients were divided according to the type of signs of congestion into three groups: A, isolated pulmonary congestion (n = 52, 15%); B, isolated peripheral congestion (n = 31, 9%); and C, signs of mixed (peripheral and central) congestion (n = 269, 76%). Patients from Group A had lower concentration of urea, bilirubin, and gamma‐glutamyl transferase whereas higher level of haematocrit, albumin, and leukocytes on admission. The highest baseline N‐terminal pro‐B‐type natriuretic peptide level (median: 4113 vs. 3634 vs. 6093 pg/mL) and percentage of patients with chronic heart failure (56 vs. 58 vs. 74%; A vs. B. vs. C, respectively, all P < 0.01) were observed in Group C. There were no differences in terms of demographics, co‐morbidities, left ventricular ejection fraction, and applied treatment between studied groups. Patients from Group A had the highest systolic blood pressure on admission (145 ± 37 vs. 122 ± 20 vs. 130 ± 29 mmHg) and the biggest decrease in systolic blood pressure [−22 (−45 to −4) vs. −2 (−13 to 2) vs. −10 (−25 to 0) mmHg] and heart rate [−16 (−35 to −1.5) vs. −1 (−10 to 5) vs. −7 (−20 to 0) b.p.m.] with the lowest weight change [−1.0 (−1.0 to 0) vs. −2.9 (−3.8 to −0.9) vs. −2.0 (−3.0 to −1.0) kg; all P < 0.01] after 48 h of hospitalization. There were differences in short‐term and long‐term outcomes with favourable results in Group A. Group A experienced less frequent in‐hospital heart failure worsening during the first 48 h (4 vs. 23 vs. 7%), had shorter length of hospital stay [6 (5–8) vs. 7 (5–11) vs. 7 (6–11) days], and had lower 1 year all‐cause mortality (12 vs. 28 vs. 29%; all P < 0.05). Presence of peripheral congestion on admission was independent predictor for all‐cause mortality within 1 year [hazard ratio (95% confidence interval): 2.68 (1.06–6.79); P = 0.04].

Conclusions

Patterns of congestion in AHF are associated with differences in clinical characteristics, treatment response, and outcomes. It needs to be considered once planning clinical trials in AHF.

Sympathetic nervous system activation and heart failure: Current state of evidence and the pathophysiology in the light of novel biomarkers

Heart failure (HF) is a complex clinical syndrome characterized by the activation of at least several neurohumoral pathways that have a common role in maintaining cardiac output and adequate perfusion pressure of target organs and tissues. The sympathetic nervous system (SNS) is upregulated in HF as evident in dysfunctional baroreceptor and chemoreceptor reflexes, circulating and neuronal catecholamine spillover, attenuated parasympathetic response, and augmented sympathetic outflow to the heart, kidneys and skeletal muscles. When these sympathoexcitatory effects on the cardiovascular system are sustained chronically they initiate the vicious circle of HF progression and become associated with cardiomyocyte apoptosis, maladaptive ventricular and vascular remodeling, arrhythmogenesis, and poor prognosis in patients with HF. These detrimental effects of SNS activity on outcomes in HF warrant adequate diagnostic and treatment modalities. Therefore, this review summarizes basic physiological concepts about the interaction of SNS with the cardiovascular system and highlights key pathophysiological mechanisms of SNS derangement in HF. Finally, special emphasis in this review is placed on the integrative and up-to-date overview of diagnostic modalities such as SNS imaging methods and novel laboratory biomarkers that could aid in the assessment of the degree of SNS activation and provide reliable prognostic information among patients with HF.

Activation of bradykinin-sensitive pericardial afferents increases systemic venous tone in conscious rats

Our understanding of reflex regulation of veins lags behind that of the arterial system. While the cardiac sympathetic afferent reflex (CSAR) exerts control over sympathetic outflow, its effect on venous tone is not known. We tested the hypothesis that activation of pericardial bradykinin sensitive afferents elicits systemic venoconstriction. Male and female Sprague Dawley rats were chronically instrumented for measurement of arterial pressure and mean circulatory filling pressure, an index of venous tone, and with an indwelling pericardial catheter. Mean arterial pressure, heart rate and mean circulatory filling pressure responses were assessed in conscious rats in response to graded pericardial injections of bradykinin (1.5-20 μg/kg) before and after ganglionic blockade, and to intravenous norepinephrine (0.05-0.8 μg/kg). Bradykinin B2 receptor was assessed by Western blot. Pericardial bradykinin injections caused graded increases in mean arterial pressure, heart rate and mean circulatory filling pressure. These responses were markedly attenuated after autonomic blockade. The increments in mean circulatory filling pressure were attenuated in female rats. There were no differences in the venoconstrictor responses to norepinephrine or ventricular bradykinin receptor expression between male and females. We interpret these findings to indicate that activation of bradykinin sensitive pericardial afferents elicits a sexually dimorphic, autonomically mediated systemic venoconstrictor response. Differences in venous smooth muscle responses to norepinephrine or ventricular bradykinin receptor expression do not account for the sexual dimorphism. We conclude that systemic venoconstriction contributes to the overall hemodynamic response to activation of the cardiac sympathetic afferent reflex and that this effect is sexually dimorphic.

Identifying novel phenotypes of acute heart failure using cluster analysis of clinical variables

BACKGROUND

Acute heart failure (AHF) is a heterogeneous disease caused by various cardiovascular (CV) pathophysiology and multiple non-CV comorbidities. We aimed to identify clinically important subgroups to improve our understanding of the pathophysiology of AHF and inform clinical decision-making.

METHODS

We evaluated detailed clinical data of 345 consecutive AHF patients using non-hierarchical cluster analysis of 77 variables, including age, sex, HF etiology, comorbidities, physical findings, laboratory data, electrocardiogram, echocardiogram and treatment during hospitalization. Cox proportional hazards regression analysis was performed to estimate the association between the clusters and clinical outcomes.

RESULTS

Three clusters were identified. Cluster 1 (n=108) represented "vascular failure". This cluster had the highest average systolic blood pressure at admission and lung congestion with type 2 respiratory failure. Cluster 2 (n=89) represented "cardiac and renal failure". They had the lowest ejection fraction (EF) and worst renal function. Cluster 3 (n=148) comprised mostly older patients and had the highest prevalence of atrial fibrillation and preserved EF. Death or HF hospitalization within 12-month occurred in 23% of Cluster 1, 36% of Cluster 2 and 36% of Cluster 3 (p=0.034). Compared with Cluster 1, risk of death or HF hospitalization was 1.74 (95% CI, 1.03-2.95, p=0.037) for Cluster 2 and 1.82 (95% CI, 1.13-2.93, p=0.014) for Cluster 3.

CONCLUSIONS

Cluster analysis may be effective in producing clinically relevant categories of AHF, and may suggest underlying pathophysiology and potential utility in predicting clinical outcomes.

Inorganic nitrate as a treatment for acute heart failure: a protocol for a single center, randomized, double-blind, placebo-controlled pilot and feasibility study

Background

Acute heart failure (AHF) is a frequent reason for hospitalization worldwide and effective treatment options are limited. It is known that AHF is a condition characterized by impaired vasorelaxation, together with reduced nitric oxide (NO) bioavailability, an endogenous vasodilatory compound. Supplementation of inorganic sodium nitrate (NaNO₃) is an indirect dietary source of NO, through bioconversion. It is proposed that oral sodium nitrate will favorably affect levels of circulating NO precursors (nitrate and nitrite) in AHF patients, resulting in reduced systemic vascular resistance, without significant hypotension.

Methods and outcomes

We propose a single center, randomized, double-blind, placebo-controlled pilot trial, evaluating the feasibility of sodium nitrate as a treatment for AHF. The primary hypothesis that sodium nitrate treatment will result in increased systemic levels of nitric oxide pre-cursors (nitrate and nitrite) in plasma, in parallel with improved vasorelaxation, as assessed by non-invasively derived systemic vascular resistance index. Additional surrogate measures relevant to the known pathophysiology of AHF will be obtained in order to assess clinical effect on dyspnea and renal function.

Discussion

The results of this study will provide evidence of the feasibility of this novel approach and will be of interest to the heart failure community. This trial may inform a larger study.

Physiological mechanisms of pulmonary hypertension

Pulmonary hypertension is usually related to obstruction of pulmonary blood flow at the level of the pulmonary arteries (eg, pulmonary embolus), pulmonary arterioles (idiopathic pulmonary hypertension), pulmonary veins (pulmonary venoocclusive disease) or mitral valve (mitral stenosis and regurgitation). Pulmonary hypertension is also observed in heart failure due to left ventricle myocardial diseases regardless of the ejection fraction. Pulmonary hypertension is often regarded as a passive response to the obstruction to pulmonary flow. We review established fluid dynamics and physiology and discuss the mechanisms underlying pulmonary hypertension. The important role that the right ventricle plays in the development and maintenance of pulmonary hypertension is discussed. We use principles of thermodynamics and discuss a potential common mechanism for a number of disease states, including pulmonary edema, through adding pressure energy to the pulmonary circulation.

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.

Serial Measurements of Splanchnic Vein Diameters in Rats Using High-Frequency Ultrasound

The purpose of this study was to investigate serial ultrasound imaging in rats as a fully non-invasive method to (1) quantify the diameters of splanchnic veins in real time as an indirect surrogate for the capacitance function of those veins, and (2) assess the effects of drugs on venous dimensions. A 21 MHz probe was used on anesthetized male Sprague–Dawley rats to collect images containing the portal vein (PV), superior mesenteric vein (SMV), abdominal inferior vena cava (IVC), and splenic vein (SpV; used as a landmark in timed studies) and the abdominal aorta (AA). Stable landmarks were established that allowed reproducible quantification of cross-sectional diameters within an animal. The average diameters of vessels measured every 5 min over 45 min remained within 0.75 ± 0.15% (PV), 0.2 ± 0.09% (SMV), 0.5 ± 0.12% (IVC), and 0.38 ± 0.06% (AA) of baseline (PV: 2.0 ± 0.12 mm; SMV: 1.7 ± 0.04 mm; IVC: 3.2 ± 0.1 mm; AA: 2.3 ± 0.14 mm). The maximal effects of the vasodilator sodium nitroprusside (SNP; 2 mg/kg, i.v. bolus) on venous diameters were determined 5 min post SNP bolus; the diameters of all noted veins were significantly increased by SNP, while mean arterial pressure (MAP) decreased 29 ± 4 mmHg. By contrast, administration of the venoconstrictor sarafotoxin (S6c; 5 ng/kg, i.v. bolus) significantly decreased PV and SpV, but not IVC, SMV, or AA, diameters 5 min post S6c bolus; MAP increased by 6 ± 2 mmHg. In order to determine if resting splanchnic vein diameters were stable over much longer periods of time, vessel diameters were measured every 2 weeks for 8 weeks. Measurements were found to be highly reproducible within animals over this time period. Finally, to evaluate the utility of vein imaging in a chronic condition, images were acquired from 4-week deoxycorticosterone acetate salt (DOCA-salt) hypertensive and normotensive (SHAM) control rats. All vessel diameters increased from baseline while MAP increased (67 ± 4 mmHg) in DOCA-salt rats compared to SHAM at 4 weeks after pellet implantation. Vessel diameters remained unchanged in SHAM animals. Together, these results support serial ultrasound imaging as a non-invasive, reliable technique able to measure acute and chronic changes in the diameter of splanchnic veins in intact rats.

Identification of nondiabetic heart failure-associated genes by bioinformatics approaches in patients with dilated ischemic cardiomyopathy

Heart failure (HF) is a common pathological condition affecting 4% of the worldwide population. However, approaches for predicting or treating nondiabetic HF (ND-HF) progression are insufficient. In the current study, the gene expression profile GSE26887 was analyzed, which contained samples from 5 healthy controls, 7 diabetes mellitus-HF patients and 12 ND-HF patients with dilated ischemic cardiomyopathy. The dataset of 5 healthy controls and 12 ND-HF patients was normalized with robust multichip average analysis and the differentially expressed genes (DEGs) were screened by unequal variance t-test and multiple-testing correction. In addition, the protein-protein interaction (PPI) network of the upregulated and downregulated genes was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins database and the Cytoscape software platform. Subsequently, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. A total of 122 upregulated and 133 downregulated genes were detected. The most significantly up- and downregulated genes were EIF1AY and SERPINE1, respectively. In addition, 38 and 77 nodes were obtained in the up- and downregulated PPI network. DEGs that owned the highest connectivity degree were USP9Y and UTY in the upregulated network, and CD44 in the downregulated networks, respectively. NPPA and SERPINE1 were also found to be hub genes in the PPI network. Several GO terms and pathways that were enriched by DEGs were identified, and the most significantly enriched KEGG pathways were drug metabolism and extracellular matrix-receptor interaction. In conclusion, the two DEGs, NPPA and SERPINE1, may be important in the pathogenesis of HF and may be used for the diagnosis and treatment of HF.

Autonomic Dysregulation as a Therapeutic Target for Acute HF

OPINION STATEMENT

Despite major advances that have led to effective therapeutic modalities for the treatment of heart failure (HF), this syndrome has continued to be a staggering health problem associated with significant mortality and morbidity. The increasing number of hospital admissions and readmissions related to acute HF continues to pose a fiscal challenge leading to constant interest in development of novel approaches. These point to multiple areas of unmet needs especially in acute HF, thus, necessitating further efforts to develop novel strategies for prevention and treatment of acute HF. One area of continuing focus is targeting the role of autonomic imbalance associated with the development of HF. Autonomic dysregulation, manifested by increased sympathetic drive and reduced parasympathetic activity, has been recognized as a mediator of increased mortality and morbidity in HF and myocardial infarction. Furthermore, vagal withdrawal has been shown to precede acute decompensation, though whether this represents cause or effect is unknown. This review discusses the potential role of autonomic dysregulation as a therapeutic modality for patients with acute decompensated HF.

Pathogenesis and clinical presentation of acute heart failure

Acute heart failure constitutes a heterogeneous clinical syndrome, whose pathophysiology is complex and not completely understood. Given the diversity of clinical presentations, several different pathophysiological mechanisms along with factors triggering circulatory decompensation are involved. This article discusses the available evidence on the pathophysiological phenomena attributed or/and associated with episodes of acute heart failure and describes different clinical profiles, which, from a clinical perspective, constitute a key element for therapeutic decision-making.

The utility of novel non-invasive technologies for remote hemodynamic monitoring in chronic heart failure

Monitoring a patient's hemodynamic status may be a revolutionary way to aid a 'health maintenance' strategy in which the physician strives to therapeutically keep the patient in an ideal hemodynamic range. Currently, home telemonitoring employs a 'crisis-prevention' approach. This strategy is still based on easily acquired measures such as heart rate, weight and blood pressure--measurements that are useful to help implement guideline-directed therapy but provide little information about impending decompensation or the risk of hospitalisation. Current systems provide limited information to personalize and adapt medication therapy for heart failure. Several innovative technologies that can remotely monitor estimates of cardiovascular hemodynamics, such as cardiac index, systemic vascular resistance, augmentation index and added heart sounds may enable earlier detection of heart failure decompensation. This editorial presents an overview of the innovative technologies that are available for non-invasive hemodynamic monitoring and maybe adapted for home telemonitoring for chronic heart failure.