Clinical and prognostic role of ammonia in advanced decompensated heart failure. The cardio-abdominal syndrome?

Microbiota alterations associated with vascular diseases: postbiotics as a next-generation magic bullet for gut-vascular axis

The intestinal microbiota represents a key element in maintaining the homeostasis and health conditions of the host. Vascular pathologies and other risk factors such as aging have been recently associated with dysbiosis. The qualitative and quantitative alteration of the intestinal microbiota hinders correct metabolic homeostasis, causing structural and functional changes of the intestinal wall itself. Impairment of the intestinal microbiota, combined with the reduction of the barrier function, worsen the pathological scenarios of peripheral tissues over time, including the vascular one. Several experimental evidence, collected in this review, describes in detail the changes of the intestinal microbiota in dysbiosis associated with vascular alterations, such as atherosclerosis, hypertension, and endothelial dysfunction, the resulting metabolic disorders and how these can impact on vascular health. In this context, the gut-vascular axis is considered, for the first time, as a merged unit involved in the development and progression of vascular pathologies and as a promising target. Current approaches for the management of dysbiosis such as probiotics, prebiotics and dietary modifications act mainly on the intestinal district. Postbiotics, described as preparation of inanimate microorganisms and/or their components that confers health benefits on the host, represent an innovative strategy for a dual management of intestinal dysbiosis and vascular pathologies. In this context, this review has the further purpose of defining the positive effects of the supplementation of bacterial strains metabolites (short‑chain fatty acids, exopolysaccharides, lipoteichoic acids, gallic acid, and protocatechuic acid) restoring intestinal homeostasis and acting directly on the vascular district through the gut-vascular axis.

Endotoxemia in Acute Heart Failure and Cardiogenic Shock: Evidence, Mechanisms and Therapeutic Options

Acute heart failure and cardiogenic shock are frequently occurring and deadly conditions. In patients with those conditions, endotoxemia related to gut injury and gut barrier dysfunction is usually described as a driver of organ dysfunction. Because endotoxemia might reciprocally alter cardiac function, this phenomenon has been suggested as a potent vicious cycle that worsens organ perfusion and leading to adverse outcomes. Yet, evidence beyond this phenomenon might be overlooked, and mechanisms are not fully understood. Subsequently, even though therapeutics available to reduce endotoxin load, there are no indications to treat endotoxemia during acute heart failure and cardiogenic shock. In this review, we first explore the evidence regarding endotoxemia in acute heart failure and cardiogenic shock. Then, we describe the main treatments for endotoxemia in the acute setting, and we present the challenges that remain before personalized treatments against endotoxemia can be used in patients with acute heart failure and cardiogenic shock.

Pretransplant Right Ventricular Dysfunction Is Associated With Increased Mortality After Heart Transplantation: A Hard Inheritance to Overcome

BACKGROUND

Right ventricular dysfunction (RVD) is a major issue in patients with advanced heart failure because it precludes the implantation of left ventricular assist device, usually leaving heart transplantation (HTx) as the only available treatment option. The pulmonary artery pulsatility index (PAPi) is a hemodynamic parameter integrating information of right ventricular function and of pulmonary circulation. Our aim is to evaluate the association of preoperative RVD, hemodynamically defined as a low PAPi, with post-HTx survival.

METHODS AND RESULTS

Consecutive adult HTx recipient at 2 Italian transplant centers between 2000 and 2018 with available data on pre-HTx right heart catheterization were included retrospectively. RVD was defined as a value of PAPi lower than the 25th percentile of the study population. The association of RVD with the 1-year post-HTx mortality and other secondary end points were evaluated. Multivariate logistic regression was used to adjust for clinical and hemodynamic variables. Analyses stratified by pulmonary vascular resistance (PVR) status (≥3 Woods units vs <3 Woods units) were also performed. Among 657 HTx recipients (female 31.1%, age 53 ± 11 years), patients with pre-HTx RVD (PAPi of <1.68) had significantly lower 1-year survival rates (77.8% vs 87.1%, P = .005), also after adjusting for estimated glomerular filtration rate, total bilirubin, PVR, serum sodium, inotropes, and mechanical circulatory support at HTx (hazard ratio 2.0, 95% confidence interval, 1.3-3.1). RVD was also associated with post-HTx renal replacement therapy (hazard ratio 2.0, 95% confidence interval 1.05-3.30) and primary graft dysfunction (hazard ratio 1.7, , 95% confidence interval 1.02-3.30). When stratifying patients by estimated PVR status, RVD was associated with worse 1-year survival among patients with normal PVR (76.9% vs 88.3%, P = .003), but not in those with increased PVR (78.6% vs 83.2%, P = .49).

CONCLUSIONS

Preoperative RVD, evaluated through PAPi, is associated with mortality and morbidity after HTx, providing incremental prognostic value over traditional clinical and hemodynamic parameters.

Prognostic Role of Ammonia in Critical Care Patients Without Known Hepatic Disease

Background and Aims: Hyperammonemia usually develops because of hepatic disease, but it may occur in patients with non-hepatic hyperammonemia (NHH). But, studies on the prognosis and possible risk factors of this disorder are lacking. The aim of this study was to find possible prognostic and risk factors for NHH in critically ill patients.

Methods: Data were extracted from MIMIC III Database. Survival was analyzed by the Kaplan-Meier method. Univariate and multivariate analyses were performed to identify prognostic factors.

Results: Valproic acid, carbamazepine, corticosteroids, recent orthopedic surgery, epilepsy, disorders of urea cycle metabolism, and obesity were found to be risk factors for NHH. Patients in the hyperammonemia group had a higher 30 day mortality than those in the non-hyperammonemia group. After final regression analysis, ammonia was found to be independent predictors of mortality.

Conclusion: Ammonia was an independent prognostic predictor of 30 day mortality for critical care patients without liver disease.

The Efficacy of Lactulose for the Treatment of Hyperammonemic Encephalopathy Due to Severe Heart Failure

Hyperammonemic encephalopathy secondary to heart failure is rare and there had been little reports about effective treatment. Organ hypoperfusion or congestion by heart failure may lead to various organ dysfunctions, and liver and intestinal circulatory impairment might cause ammonia metabolic failure. Here, we report on the case of a patient with hyperammonemic encephalopathy that was secondary to heart failure, which was effectively treated by lactulose.

Diuretic treatment in high-risk acute decompensation of advanced chronic heart failure-bolus intermittent vs. continuous infusion of furosemide: a randomized controlled trial

BACKGROUND

Diuretic resistance is a common issue in patients with acute decompensation of advanced chronic heart failure (ACHF). The aim of this trial was to compare boluses and continuous infusion of furosemide in a selected population of patients with ACHF and high risk for diuretic resistance.

METHODS

In this single-centre, double-blind, double-dummy, randomized trial, we enrolled 80 patients admitted for acute decompensation of ACHF (NYHA IV, EF ≤ 30%) with criteria of high risk for diuretic resistance (SBP ≤ 110 mmHg, wet score ≥ 12/18, and sodium ≤ 135 mMol/L). Patients were assigned in a 1:1 ratio to receive furosemide by bolus every 12 h or by continuous infusion. Diuretic treatment and dummy treatment were prepared by a nurse unassigned to patients' care. The study treatment was continued for up to 72 h. Coprimary endpoints were total urinary output and freedom from congestion at 72 h.

RESULTS

80 patients were enrolled with 40 patients in each treatment arm. Mean daily furosemide was 216 mg in continuous-infusion arm and 195 mg in the bolus intermittent arm. Freedom from congestion (defined as jugular venous pressure of < 8 cm, with no orthopnea and with trace peripheral edema or no edema) occurred more in the continuous infusion than in the bolus arm (48% vs. 25%, p = 0.04), while total urinary output after 72 h was 8612 ± 2984 ml in the bolus arm and 10,020 ± 3032 ml in the continuous arm (p = 0.04). Treatment failure occurred less in the continuous-infusion group (15% vs. 38%, p = 0.02), while there was no significant difference between groups in the incidence of worsening of renal function.

CONCLUSION

Among patients with acute decompensation of ACHF and high risk of diuretic resistance, continuous infusion of intravenous furosemide was associated with better decongestion.

DRAIN TRIAL

ClinicalTrials.gov number NCT03592836.

Evaluation and Management of Right-Sided Heart Failure: A Scientific Statement From the American Heart Association

Background and Purpose:

The diverse causes of right-sided heart failure (RHF) include, among others, primary cardiomyopathies with right ventricular (RV) involvement, RV ischemia and infarction, volume loading caused by cardiac lesions associated with congenital heart disease and valvular pathologies, and pressure loading resulting from pulmonic stenosis or pulmonary hypertension from a variety of causes, including left-sided heart disease. Progressive RV dysfunction in these disease states is associated with increased morbidity and mortality. The purpose of this scientific statement is to provide guidance on the assessment and management of RHF.

Methods:

The writing group used systematic literature reviews, published translational and clinical studies, clinical practice guidelines, and expert opinion/statements to summarize existing evidence and to identify areas of inadequacy requiring future research. The panel reviewed the most relevant adult medical literature excluding routine laboratory tests using MEDLINE, EMBASE, and Web of Science through September 2017. The document is organized and classified according to the American Heart Association to provide specific suggestions, considerations, or reference to contemporary clinical practice recommendations.

Results:

Chronic RHF is associated with decreased exercise tolerance, poor functional capacity, decreased cardiac output and progressive end-organ damage (caused by a combination of end-organ venous congestion and underperfusion), and cachexia resulting from poor absorption of nutrients, as well as a systemic proinflammatory state. It is the principal cause of death in patients with pulmonary arterial hypertension. Similarly, acute RHF is associated with hemodynamic instability and is the primary cause of death in patients presenting with massive pulmonary embolism, RV myocardial infarction, and postcardiotomy shock associated with cardiac surgery. Functional assessment of the right side of the heart can be hindered by its complex geometry. Multiple hemodynamic and biochemical markers are associated with worsening RHF and can serve to guide clinical assessment and therapeutic decision making. Pharmacological and mechanical interventions targeting isolated acute and chronic RHF have not been well investigated. Specific therapies promoting stabilization and recovery of RV function are lacking.

Conclusions:

RHF is a complex syndrome including diverse causes, pathways, and pathological processes. In this scientific statement, we review the causes and epidemiology of RV dysfunction and the pathophysiology of acute and chronic RHF and provide guidance for the management of the associated conditions leading to and caused by RHF.

Ammonia lowering reverses sarcopenia of cirrhosis by restoring skeletal muscle proteostasis

Sarcopenia or skeletal muscle loss is a frequent, potentially reversible complication in cirrhosis that adversely affects clinical outcomes. Hyperammonemia is a consistent abnormality in cirrhosis that results in impaired skeletal muscle protein synthesis and breakdown (proteostasis). Despite the availability of effective ammonia-lowering therapies, whether lowering ammonia restores proteostasis and increases muscle mass is unknown. Myotube diameter, protein synthesis, and molecular responses in C2C12 murine myotubes to withdrawal of ammonium acetate following 24-hour exposure to 10 mM ammonium acetate were complemented by in vivo studies in the hyperammonemic portacaval anastomosis rat and sham-operated, pair-fed Sprague-Dawley rats treated with ammonia-lowering therapy by l-ornithine l-aspartate and rifaximin orally for 4 weeks. We observed reduced myotube diameter, impaired protein synthesis, and increased autophagy flux in response to hyperammonemia, which were partially reversed following 24-hour and 48-hour withdrawal of ammonium acetate. Consistently, 4 weeks of ammonia-lowering therapy resulted in significant lowering of blood and skeletal muscle ammonia, increase in lean body mass, improved grip strength, higher skeletal muscle mass and diameter, and an increase in type 2 fibers in treated compared to untreated portacaval anastomosis rats. The increased skeletal muscle myostatin expression, reduced mammalian target of rapamycin complex 1 function, and hyperammonemic stress response including autophagy markers normally found in portacaval anastomosis rats were reversed by treatment with ammonia-lowering therapy. Despite significant improvement, molecular and functional readouts were not completely reversed by ammonia-lowering measures.

CONCLUSION

Ammonia-lowering therapy results in improvement in skeletal muscle phenotype and function and molecular perturbations of hyperammonemia; these preclinical studies complement previous studies on ammonia-induced skeletal muscle loss and lay the foundation for prolonged ammonia-lowering therapy to reverse sarcopenia of cirrhosis. (Hepatology 2017;65:2045-2058).

Gut Bacteria and Hydrogen Sulfide: The New Old Players in Circulatory System Homeostasis

Accumulating evidence suggests that gut bacteria play a role in homeostasis of the circulatory system in mammals. First, gut bacteria may affect the nervous control of the circulatory system via the sensory fibres of the enteric nervous system. Second, gut bacteria-derived metabolites may cross the gut-blood barrier and target blood vessels, the heart and other organs involved in the regulation of the circulatory system. A number of studies have shown that hydrogen sulfide (H₂S) is an important biological mediator in the circulatory system. Thus far, research has focused on the effects of H₂S enzymatically produced by cardiovascular tissues. However, some recent evidence indicates that H₂S released in the colon may also contribute to the control of arterial blood pressure. Incidentally, sulfate-reducing bacteria are ubiquitous in mammalian colon, and H₂S is just one among a number of molecules produced by the gut flora. Other gut bacteria-derived compounds that may affect the circulatory system include methane, nitric oxide, carbon monoxide, trimethylamine or indole. In this paper, we review studies that imply a role of gut microbiota and their metabolites, such as H₂S, in circulatory system homeostasis.