Arginine vasopressin as a target in the treatment of acute heart failure

The role of tolvaptan add-on therapy in patients with acute heart failure: a systematic review and network meta-analysis

Background

Several conflicting reviews have concluded that the use of loop diuretics is associated with poorer clinical and safety outcomes. Therefore, this study aimed to investigate the efficacy and safety of tolvaptan as an adjunct to conventional diuretic therapy in patients with acute heart failure (AHF).

Methods

A comprehensive search was conducted on PubMed, Embase, ProQuest, EBSCO, and Cochrane Library until 24 May 2023 to identify randomized controlled trials that compared the effects of tolvaptan with conventional therapy and placebo in patients with AHF. The quality assessment of the included trials was conducted using the Cochrane risk of bias. A network meta-analysis (NMA) was conducted to examine the dosage effect of tolvaptan.

Result

A total of 17 studies with 18 reports, involving 10,039 patients, were selected. The tolvaptan add-on therapy significantly alleviated dyspnea [24 h: RR 1.16 (1.04, 1.29), 48 h: RR 1.18 (1.04, 1.33)], reduced body weight within 48 h [Asian group, MD -0.93 (-1.48, -0.38); non-Asian group, MD -2.76 (-2.88, -2.65)], reduced edema [RR 1.08 (1.02, 1.15)], increased serum sodium [non-Asian group, MD 3.40 (3.02, 3.78)], and resulted in a change in serum creatinine [MD -0.10 (-0.18, -0.01)]. No significant differences were observed in mortality and rehospitalization. The NMA suggested that an intermediate dosage (15 mg/day) might offer the best efficacy in reducing dyspnea within 24 h, reducing edema, increasing serum sodium, and lowering the incidence of worsening renal function (WRF).

Conclusion

In conclusion, the meta-analysis showed that tolvaptan contributed to the short-term alleviation of congestive symptoms, elevated sodium levels, and a lower incidence of WRF. However, no significant benefits were observed in long-term symptoms, rehospitalization rates, and mortality. An intermediate dosage of tolvaptan might be considered the optimal choice for various clinical outcomes.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023420288).

Involvement of Vasopressin in Tissue Hypoperfusion during Cardiogenic Shock Complicating Acute Myocardial Infarction in Rats

Acute heart failure (AHF) due to acute myocardial infarction (AMI) is likely to involve cardiogenic shock (CS), with neuro-hormonal activation. A relationship between AHF, CS and vasopressin response is suspected. This study aimed to investigate the implication of vasopressin on hemodynamic parameters and tissue perfusion at the early phase of CS complicating AMI. Experiments were performed on male Wistar rats submitted or not to left coronary artery ligation (AMI and Sham). Six groups were studied Sham and AMI treated or not with either a vasopressin antagonist SR-49059 (Sham-SR, AMI-SR) or agonist terlipressin (Sham-TLP, AMI-TLP). Animals were sacrificed one day after surgery (D₁) and after hemodynamic parameters determination. Vascular responses to vasopressin were evaluated, ex vivo, on aorta. AHF was defined by a left ventricular ejection fraction below 40%. CS was defined by AHF plus tissue hypoperfusion evidenced by elevated serum lactate level or low mesenteric oxygen saturation (SmO₂) at D₁. Mortality rates were 40% in AMI, 0% in AMI-SR and 33% in AMI-TLP. Immediately after surgery, a sharp decrease in SmO₂ was observed in all groups. At D₁, SmO₂ recovered in Sham and in SR-treated animals while it remained low in AMI and further decreased in TLP-treated groups. The incidence of CS among AHF animals was 72% in AMI or AMI-TLP while it was reduced to 25% in AMI-SR. Plasma copeptin level was increased by AMI. Maximal contractile response to vasopressin was decreased in AMI (32%) as in TLP- and SR- treated groups regardless of ligation. Increased vasopressin secretion occurring in the early phase of AMI may be responsible of mesenteric hypoperfusion resulting in tissue hypoxia. Treatment with a vasopressin antagonist enhanced mesenteric perfusion and improve survival. This could be an interesting therapeutic strategy to prevent progression to cardiogenic shock.

Phosphorylation of CaMK and CREB-Mediated Cardiac Aldosterone Synthesis Induced by Arginine Vasopressin in Rats with Myocardial Infarction

Both aldosterone and arginine vasopressin (AVP) are produced in the heart and may participate in cardiac fibrosis. However, their relationship remains unknown. This study aims to demonstrate the regulation and role of AVP in aldosterone synthesis in the heart. Rats were subjected to a sham operation or myocardial infarction (MI) by ligating the coronary artery. Cardiac function and fibrosis were assessed using echocardiography and immunohistochemical staining, respectively. In addition, the effects of AVP stimulation on cardiac microvascular endothelial cells (CMECs) were studied using ELISA, real-time PCR, and Western blotting. Compared with the rats having undergone a sham operation, the MI rats had an increased LVMI, type I collagen composition, and concentrations of aldosterone and AVP in the heart but decreased cardiac function. As the MI rats aged, the LVMI, type I collagen, aldosterone, and AVP increased, while the LVMI decreased. Furthermore, AVP time-dependently induced aldosterone secretion and CYP11B2 mRNA expression in CMECs. The p-CREB levels were significantly increased by AVP. Nevertheless, these effects were completely blocked by SR49059 or partially inhibited by KN93. This study demonstrated that AVP could induce the secretion of local cardiac aldosterone, which may involve CaMK and CREB phosphorylation and CYP11B2 upregulation through V1 receptor activation.

Novel Biomarkers of Renal Dysfunction and Congestion in Heart Failure

Heart failure is a major public health problem and, despite the constantly emerging, new, effective treatments, it remains a leading cause of morbidity and mortality. Reliable tools for early diagnosis and risk stratification are crucial in the management of HF. This explains a growing interest in the development of new biomarkers related to various pathophysiological mechanisms of HF. In the course of this review, we focused on the markers of congestion and renal dysfunction in terms of their interference with cardiovascular homeostasis. Congestion is a hallmark feature of heart failure, contributing to symptoms, morbidity, and hospitalizations of patients with HF and has, therefore, become a therapeutic target in AHF. On the other hand, impaired renal function by altering the volume status contributes to the development and progression of HF and serves as a marker of an adverse clinical outcome. Early detection of congestion and an adequate assessment of renal status are essential for the prompt administration of patient-tailored therapy. This review provides an insight into recent advances in the field of HF biomarkers that could be potentially implemented in diagnosis and risk stratification of patients with HF.

The historical evolution of knowledge of the involvement of neurohormonal systems in the pathophysiology and treatment of heart failure

Our knowledge of the pathophysiology of heart failure (HF) underwent profound changes during the 1980s. Once thought to be of exclusively structural origin, HF began to be seen as the consequence of hormonal imbalance. A number of seminal studies were published in that decade focusing on the impact of neurohormonal activation in HF. Presently, eight neurohormonal systems are known to have a key role in HF development: four stimulate vasoconstriction and sodium/water retention (the sympathetic nervous system, the renin-angiotensin-aldosterone system [RAAS], endothelin, and the vasopressin-arginine system), while the other four stimulate vasodilation and natriuresis (the prostaglandin system, nitric oxide, the dopaminergic system, and the natriuretic peptide system [NPS]). These systems are strongly interconnected and are subject to intricate regulation, functioning together in a delicate homeostasis. Disruption of this homeostasis is characteristic of HF. This review explores the historical development of knowledge on the impact of the neurohormonal systems on HF pathophysiology, from the first studies to current understanding. In addition, the therapeutic potential of each of these systems is discussed, and currently used neurohormonal antagonists are characterized. Special emphasis is given to the latest drug approved for use in HF with reduced ejection fraction, sacubitril/valsartan. This drug combines two different molecules, acting on two different systems (RAAS and NPS) simultaneously.

Small molecules for modulating the localisation of the water channel aquaporin-2-disease relevance and perspectives for targeting local cAMP signalling

The tight spatial and temporal organisation of cyclic adenosine monophosphate (cAMP) signalling plays a key role in arginine-vasopressin (AVP)-mediated water reabsorption in renal collecting duct principal cells and in a plethora of other processes such as in the control of cardiac myocyte contractility. This review critically discusses in vitro- and cell-based screening strategies for the identification of small molecules that interfere with AVP/cAMP signalling in renal principal cells; it features phenotypic screening and approaches for targeting protein-protein interactions of A-kinase anchoring proteins (AKAPs), which organise local cAMP signalling hubs. The discovery of novel chemical entities for the modulation of local cAMP will not only provide tools for elucidating molecular mechanisms underlying cAMP signalling. Novel chemical entities can also serve as starting points for the development of novel drugs for the treatment of human diseases. Examples illustrate how screening for small molecules can pave the way to novel approaches for the treatment of certain forms of diabetes insipidus, a disease caused by defects in AVP-mediated water reabsorption.

Frequent drinking of small volumes improves cardiac function and survival in rats with chronic heart failure

Fluid retention is the main reason for the high hospitalization rate among patients with chronic heart failure (CHF). Given the lack of knowledge about fluid intake regulation and its consequences in patients with CHF, current guidelines do not provide clear direction for fluid management. Using a rat model of CHF, we investigated altering drinking behaviors and explored fluid management strategies. CHF was induced by ligating the left anterior descending coronary arteries in 8‐week‐old, male, Sprague‐Dawley rats. A custom‐designed drop counting and feedback control system was used to record and modulate drinking behaviors. During the first month after an induced myocardial infarction (MI), we observed that the spontaneous per drinking volume (PDV) was significantly increased in animals with prolonged intervals between drinking episodes. In addition, there was a significant inverse correlation between the early PDV and the post‐MI lifespan (r = −0.907; P < 0.001). Moreover, modulating the drinking behavior of rats with CHF to involve frequent drinking of small PDVs significantly enhanced hemodynamics and prevented cardiac remodeling, with a significant improvement in the 180‐day survival rate, compared with animals allowed to drink freely (50% vs. 36%; P < 0.01). The results of dynamic PDV changes, after MI, suggest that an impaired thirst mechanism is associated with the sensing and regulating of fluid balance in rats with CHF. These results suggest that increasing the drinking frequency, with small PDVs, may be beneficial to preventing progression of cardiac dysfunction in CHF.

Tolvaptan promotes urinary excretion of sodium and urea: a retrospective cohort study

BACKGROUND

Tolvaptan (TLV) promotes aquaresis; however, little is known about its effect on solute excretion in chronic kidney disease (CKD).

METHODS

We retrospectively studied CKD patients with decompensated heart failure (HF) or those with autosomal dominant polycystic kidney disease (ADPKD) receiving TLV. Patients with an increased urine volume of more than twice of daily variance were defined as "responders" in HF. We compared the ability of the urinary osmolality (U-OSM) change and urinary creatinine concentration ([U-Cr]) change to discriminate "responders". The fractional excretion of sodium (FeNa) and urea nitrogen (FeUN), and blood urea nitrogen (BUN) were monitored.

RESULTS

In 30 responders among 53 HF patients, TLV increased FeUN significantly from 36.1 to 44.2% after starting TLV, but not FeNa. Since U-OSM is determined partially by urinary UN concentration, the decrease of [U-Cr] after treatment outperformed the U-OSM decrement to discriminate responders, as shown in receiver operating characteristic curve analysis and significantly higher net reclassification index. In 13 ADPKD patients, TLV increased FeUN (34.8, 47.3%, p = 0.02), and significant decrease of BUN by 2.3 (95% confidence interval 0.4-4.2) mg/dL was observed even 3 months after the intervention. Systolic blood pressure decreased significantly by 14.2 (95% confidence interval 4.0-24.4) mmHg along with the increase in FeNa, leading to reduced dosage of antihypertensives in 6 patients.

CONCLUSION

TLV promotes the excretion of sodium and urea. The change in [U-Cr] is useful for early discrimination of responders. Hypotension should be carefully monitored during high-dose TLV therapy.

Relation between change in exercise capacity and change in blood amino acids in patients with chronic heart failure

[Purpose] Although cardiac rehabilitation (CR) is recommended for patients with chronic heart failure (CHF), adequate exercise effect cannot be obtained in elderly patients. Administration of amino acids (AA) to CHF patients has been reported to improve exercise capacity, but the changes in AA composition in plasma before and after CR had not been reported. This study aimed to measure plasma levels of AA in CHF patients and compare with values of normal range. In addition the relationship between the change of exercise capacity and AA were examined. [Subjects and Methods] Twelve CHF patients (60% males, aged 68 ± 12 years) were studied. The correction between the rates of changes in exercise capacity parameters and in plasma AA levels was investigated. [Results] Anaerobic threshold (AT) and peak oxygen uptake (VO2) improved significantly after CR. The AA profile showed no specific pattern, and citrulline (Cit) was the amino acid showing a significant positive correlation with exercise capacity (∆Cit vs. ∆AT: r=0.602, ∆Cit vs. ∆AT-work rate (WR): r=0.681, ∆Cit vs. ∆VO2/WR: r=0.635). A tendency of positive correlation was observed between ∆Cit and ∆peak VO2 (r=0.456). [Conclusion] The AA profile showed no specific pattern, but a relationship between change in exercise capacity and Cit were found.

The Trafficking of the Water Channel Aquaporin-2 in Renal Principal Cells-a Potential Target for Pharmacological Intervention in Cardiovascular Diseases

Arginine-vasopressin (AVP) stimulates the redistribution of water channels, aquaporin-2 (AQP2) from intracellular vesicles into the plasma membrane of renal collecting duct principal cells. By this AVP directs 10% of the water reabsorption from the 170 L of primary urine that the human kidneys produce each day. This review discusses molecular mechanisms underlying the AVP-induced redistribution of AQP2; in particular, it provides an overview over the proteins participating in the control of its localization. Defects preventing the insertion of AQP2 into the plasma membrane cause diabetes insipidus. The disease can be acquired or inherited, and is characterized by polyuria and polydipsia. Vice versa, up-regulation of the system causing a predominant localization of AQP2 in the plasma membrane leads to excessive water retention and hyponatremia as in the syndrome of inappropriate antidiuretic hormone secretion (SIADH), late stage heart failure or liver cirrhosis. This article briefly summarizes the currently available pharmacotherapies for the treatment of such water balance disorders, and discusses the value of newly identified mechanisms controlling AQP2 for developing novel pharmacological strategies. Innovative concepts for the therapy of water balance disorders are required as there is a medical need due to the lack of causal treatments.

Effectiveness of single dose conivaptan for correction of hyponatraemia in post-operative patients following major head and neck surgeries

Background and Aims:

Conivaptan, a vasopressin receptor antagonist, is commonly used for the treatment of euvolaemic, hypervolaemic hyponatraemia. Usually, an intravenous (IV) bolus followed by infusion is administered for many days. We decided to assess the effectiveness of single dose conivaptan for correction of hyponatraemia in post-operative patients.

Methods:

This was a prospective, randomised trial conducted in 40 symptomatic post-operative Intensive Care Unit (ICU) patients with a serum sodium level of ≤130 mEq/L. Group A patients received IV conivaptan 20 mg over 30 min, whereas in group B infusion of 3% hypertonic saline was started as an infusion at the rate of 20–30 ml/h. Serum sodium levels were measured at 12, 24, 48 and 72 h and the daily fluid balance was measured for 3 days. The Chi-square test, Wilcoxon signed rank test and Mann-Whitney tests were used as applicable.

Results:

The serum sodium levels before initiating treatment were comparable between groups. However, subsequent sodium levels at 12, 24 and 48 h showed significantly high values in group A. Though at 72 h the mean sodium value was high in group A, it was not statistically significant. Group A showed a significantly high fluid loss on day 1, 2 and 3. The mean volume of hypertonic saline required in group B showed a steady decline from day 1 to 3 and only 13 patients required hypertonic saline on the 3^rd day.

Conclusion:

Single dose conivaptan is effective in increasing serum sodium levels in post-operative ICU patients up to 72 h associated with a significant negative fluid balance.