Sequential nephron blockade breaks resistance to diuretics in edematous states

Congestion in Heart Failure: From the Secret of a Mummy to Today's Novel Diagnostic and Therapeutic Approaches: A Comprehensive Review

This review paper presents a review of the evolution of this disease throughout the centuries, describes and summarizes the pathophysiologic mechanisms, briefly discusses the mechanism of action of diuretics, presents their role in decongesting heart failure in patients, and reveals the data behind ultrafiltration in the management of acutely or chronically decompensated heart failure (ADHF), focusing on all the available data and advancements in this field. Acutely decompensated heart failure (ADHF) presents a critical clinical condition characterized by worsening symptoms and signs of heart failure, necessitating prompt intervention to alleviate congestion and improve cardiac function. Diuretics have traditionally been the mainstay for managing fluid overload in ADHF. Mounting evidence suggests that due to numerous causes, such as coexisting renal failure or chronic use of loop diuretics, an increasing rate of diuretic resistance is noticed and needs to be addressed. There has been a series of trials that combined diuretics of different categories without the expected results. Emerging evidence suggests that ultrafiltration may offer an alternative or adjunctive approach.

Effect of Acetazolamide as Add-On Diuretic Therapy in Patients With Heart Failure: A Meta-Analysis

The aim of this meta-analysis was to assess the effectiveness of acetazolamide as an add-on diuretic therapy in patients with heart failure. This meta-analysis was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. A systematic literature search was independently performed by two authors using MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews to identify relevant studies assessing the use of acetazolamide in patients with heart failure. The search keywords included "acetazolamide" and "heart failure". The outcomes assessed in this meta-analysis included natriuresis (mmol/L), diuresis (Liters) and decongestion (absence of signs of volume overload) by 72 hours. Other outcomes assessed in this meta-analysis included hospitalization due to heart failure and all-cause mortality. A total of three studies included a total of 569 heart failure patients. The number of patients achieved decongestion was significantly higher in patients receiving acetazolamide compared to the patients randomized in the control group (RR: 1.34, 95% CI: 1.06-1.67). Compared to patients in the control group, mean natriuresis was significantly higher in acetazolamide patients (MD: 74.91, 95% CI: 39.85-109.97). Diuresis was significantly higher in patients receiving acetazolamide compared to the control group (MD: 0.44, 95% CI: 0.16-0.72). No significant difference was found between the two groups in terms of all-cause mortality and hospitalization due to heart failure. In conclusion, our meta-analysis suggests that acetazolamide may have beneficial impacts on heart failure patients by increasing the number of successful decongestions. Additionally, patients who were treated with acetazolamide had significantly higher natriuresis and diuresis compared to patients in the control group.

Pathophysiology-Based Management of Acute Heart Failure

Even though acute heart failure (AHF) is one of the most common admission diagnoses globally, its pathogenesis is poorly understood, and there are few effective treatments available. Despite an heterogenous onset, congestion is the leading contributor to hospitalization, making it a crucial therapeutic target. Complete decongestion, nevertheless, may be hard to achieve, especially in patients with reduced end organ perfusion. In order to promote a personalised pathophysiological-based therapy for patients with AHF, we will address in this review the pathophysiological principles that underlie the clinical symptoms of AHF as well as examine how to assess them in clinical practice, suggesting that gaining a deeper understanding of pathophysiology might result in significant improvements in HF therapy.

Diuretic resistance in patients with kidney disease: Challenges and opportunities

Edema caused by kidney disease is called renal edema. Edema is a common symptom of many human kidney diseases. Patients with renal edema often need to take diuretics.However, After taking diuretics, patients with kidney diseases are prone to kidney congestion, decreased renal perfusion, decreased diuretics secreted by renal tubules, neuroendocrine system abnormalities, abnormal ion transporter transport, drug interaction, electrolyte disorder, and hypoproteinemia, which lead to ineffective or weakened diuretic use and increase readmission rate and mortality. The main causes and coping strategies of diuretic resistance in patients with kidney diseases were described in detail in this report. The common causes of DR included poor diet (electrolyte disturbance and hypoproteinemia due to patients' failure to limit diet according to correct sodium, chlorine, potassium, and protein level) and poor drug compliance (the patient did not take adequate doses of diuretics. true resistance occurs only if the patient takes adequate doses of diuretics, but they are not effective), changes in pharmacokinetics and pharmacodynamics, electrolyte disorders, changes in renal adaptation, functional nephron reduction, and decreased renal blood flow. Common treatment measures include increasing in the diuretic dose and/or frequency, sequential nephron blockade,using new diuretics, ultrafiltration treatment, etc. In clinical work, measures should be taken to prevent or delay the occurrence and development of DR in patients with kidney diseases according to the actual situation of patients and the mechanism of various causes. Currently, there are many studies on DR in patients with heart diseases. Although the phenomenon of DR in patients with kidney diseases is common, there is a relatively little overview of the mechanism and treatment strategy of DR in patients with kidney diseases. Therefore, this paper hopes to show the information on DR in patients with kidney diseases to clinicians and researchers and broaden the research direction and ideas to a certain extent.

Quantification and treatment of congestion in heart failure: A clinical and pathophysiological overview

Renal sodium and water retention with resulting extracellular volume expansion and redistribution are hallmark features of heart failure syndromes. However, congestion assessment, monitoring, and treatment represent a real challenge in daily clinical practice. This document reviewed historical and contemporary evidence of available methods for determining volume status and discuss pharmacological aspects and pathophysiological principles that underlie diuretic use.

Impact of Loop Diuretic on Outcomes in Patients with Heart Failure and Reduced Ejection Fraction

PURPOSE OF REVIEW

Loop diuretics are the cornerstone of the treatment of congestion in heart failure patients. The manuscript aims to summarize the most updated information regarding the use of loop diuretics in heart failure.

RECENT FINDINGS

Diuretic response can be highly variable between patients and needs to be carefully evaluated during and after the hospitalization. Diuretic resistance can lead to residual congestion which affects prognosis and can be difficult to detect. The effect of loop diuretics on long-term prognosis remains uncertain but patients with advanced heart failure typically have renal dysfunction and are more inclined to develop loop diuretic resistance, which may lead to an incomplete decongestion and thus to a worse prognosis. Loop diuretics are the most potent diuretics available and their use is recommended in order to alleviate symptoms, improve exercise capacity, and reduce hospitalizations in patients with heart failure. Their use should be limited to the lowest dose necessary to maintain euvolemia because a low dose does not increase the risk of decompensation but reduce the risk of adverse effects and allow the up-titration of disease-modifying drugs.

Metolazone Add-On Therapy in Heart Failure: A Cohort Study from Persian Registry of Cardiovascular Disease/Heart Failure (PROVE/HF)

Background

One of the strategies for overcoming diuretic resistance among heart failure (HF) patients is adding thiazide-type diuretics. The main aim of this article is to compare the adverse clinical outcomes, including death and re-hospitalization, among individuals suffering from severe acute decompensated HF (ADHF) that consumed furosemide or furosemide plus metolazone.

Methods

This retrospective cohort study was done in the context of the Persian registry of cardiovascular disease (PROVE) from September 2017 to September 2018. One thousand and four hundred thirty-eight individuals (furosemide: 972 and furosemide plus metolazone: 466) with the final diagnosis of severe ADHF (left ventricular ejection fraction < 30%) were selected and followed for 10.3 ± 7.8 months. The association between two groups, as mentioned above, with the incidence of death and re-admission, was evaluated with different models.

Results

The mean age of the study population was 68.19 ± 12.98 years. There was no significant relation in terms of death or re-hospitalization between patients with different diuretic regimens. After adjustment of potential confounders, we found that adding metolazone as an adjuvant HF therapy was not independently associated with death or re-hospitalization (hazard ratio (HR): 0.78,95% confidence interval (CI) = 0.59–1.03, P = 0.085, and odds ratio (OR): 0.80, 95% CI: 0.60–1.07, P = 0.135, respectively).

Conclusion

Our findings revealed that adding metolazone in patients with furosemide resistance is not associated with higher morbidity and mortality. Therefore, usage of these two therapeutic agents could be a helpful strategy for severe HF patients.

Multinephron Segment Diuretic Therapy to Overcome Diuretic Resistance in Acute Heart Failure: A Single-Center Experience

BACKGROUND

The concept of multinephron segment diuretic therapy (MSDT) has been recommended in severe diuretic resistance with only expert opinion and case-level evidence. The purpose of this study was to investigate the safety and efficacy of MSDT, combining 4 diuretic classes, in acute heart failure (AHF) complicated by diuretic resistance.

METHODS AND RESULTS

A retrospective analysis was conducted in patients hospitalized with AHF at a single medical center who received MSDT, including concomitant carbonic anhydrase inhibitor, loop, thiazide, and mineralocorticoid receptor antagonist diuretics. Subjects served as their own controls with efficacy evaluated as urine output and weight change before and after MSDT. Serum chemistries, renal replacement therapies, and in-hospital mortality were evaluated for safety. Patients with severe diuretic resistance before MSDT were analyzed as a subcohort. A total of 167 patients with AHF and diuretic resistance received MSDT. MSDT was associated with increased median 24-hour urine output in the first day of therapy compared with the previous day (2.16 L [0.95-4.14 L] to 3.08 L [1.74-4.86 L], P = .003) in the total cohort and in the Severe diuretic resistance cohort (0.91 L [0.43-1.43 L] to 2.08 L [1.13-3.96 L], P < .001). The median cumulative weight loss at day 7 or discharge was -7.4 kg (-15.3 to -3.4 kg) (P = .02). Neither serum sodium, chloride, potassium, bicarbonate, or creatinine changed significantly relative to baseline (P > .05 for all).

CONCLUSIONS

In an AHF cohort with diuretic resistance, MSDT was associated with increased diuresis without changes in serum chemistries or kidney function. Prospective studies of MSDT in AHF and diuretic resistance are warranted.

Quantification and Treatment of Congestion in Heart Failure: A Clinical and Pathophysiological Overview

Renal sodium and water retention with resulting extracellular volume expansion and redistribution are hallmark features of heart failure syndromes. However, congestion assessment, monitoring, and treatment represent a real challenge in daily clinical practice. This document reviewed historical and contemporary evidence of available methods for determining volume status and discuss pharmacological aspects and pathophysiological principles that underlie diuretic use.

Tailoring the management of hypertension to comorbidities

PURPOSE OF REVIEW

In this article, we review the most current evidence for initiation and maintenance of various antihypertension (HTN) drug classes, including other misconceptions with respect to common comorbidities in patients with HTN.

RECENT FINDINGS

Although the currently available anti-HTN agents have broad applicability in treating HTN, additional agents, such as angiotensin receptor-neprilysin inhibitors and novel nonsteroidal mineralocorticoid antagonists, have recently gained clinical significance. In addition, there have been some anecdotal concerns regarding the adverse effects, indications, and risks of COVID-19 infection/mortality when using certain anti-HTN agents.

SUMMARY

Current guidelines currently address the treatment of primary HTN. However, isolated HTN is uncommon and often involves comorbid diseases that require specific regimentation. Several experimental medications are currently in late-stage trials showing potential superiority over current drugs that are available in the market.

The pathophysiology and management of diuretic resistance in patients with heart failure

OBJECTIVES

The objectives of the study are to investigate the causes of diuretic resistance in patients with advanced congestive heart failure (CHF), since diuretics are the cornerstone of treatment of these patients. Several studies have shown that diuretic resistance in patients with advanced CHF is common, ranging from 25% to 50% in hospitalized patients.

METHODS

In order to get a current perspective as to the magnitude of diuretic resistance in such patients, a focused Medline search of the English language literature was conducted between 2015 and 2020 using the search terms, CHF, diuretics, treatment, resistance, frequency, and 30 papers with pertinent information were selected.

RESULTS

The analysis of data from the selected papers demonstrated that diuretic resistance is common in hospitalized patients with advanced CHF and frequently associated with renal failure, which is secondary to CHF.

CONCLUSIONS

Diuretic resistance appears to be common in patients with advanced CHF and it is mostly due to decreased cardiac output, low blood pressure, decreased glomerular filtration rate, decreased filtration of sodium, and increased tubular reabsorption of sodium. Diuretic resistance in such patients can be overcome with the combination of loop diuretics with thiazide and thiazide-like diuretics, aldosterone antagonists, as well as other agents. The data from these studies in combination with collateral literature will be discussed in this review.

Usefulness of acetazolamide in the management of diuretic resistance

Worsening symptoms and fluid overload are the hallmarks of heart failure (HF) decompensation, and fluid removal is central to improvement. Despite high-dose loop diuretics, patients with decompensated HF may develop suboptimal diuresis/diuretic resistance. Sequential nephron blockade with a combination of loop and thiazide/thiazide-like diuretics may be insufficient, resulting in poor outcomes. We present a case wherein urine output improved significantly with acetazolamide. Although the diuretic capacity of acetazolamide is weak on its own, it might be efficient in aiding the efficacy of loop diuretics. We discuss the pathophysiological basis and evidence behind its potential role in diuretic resistance. Drawing from current understanding, we propose a stepwise approach to diuresis in such patients.

Pathophysiology of Diuretic Resistance and Its Implications for the Management of Chronic Heart Failure

Diuretic resistance implies a failure to increase fluid and sodium (Na+) output sufficiently to relieve volume overload, edema, or congestion, despite escalating doses of a loop diuretic to a ceiling level (80 mg of furosemide once or twice daily or greater in those with reduced glomerular filtration rate or heart failure). It is a major cause of recurrent hospitalizations in patients with chronic heart failure and predicts death but is difficult to diagnose unequivocally. Pharmacokinetic mechanisms include the low and variable bioavailability of furosemide and the short duration of all loop diuretics that provides time for the kidneys to restore diuretic-induced Na+ losses between doses. Pathophysiological mechanisms of diuretic resistance include an inappropriately high daily salt intake that exceeds the acute diuretic-induced salt loss, hyponatremia or hypokalemic, hypochloremic metabolic alkalosis, and reflex activation of the renal nerves. Nephron mechanisms include tubular tolerance that can develop even during the time that the renal tubules are exposed to a single dose of diuretic, or enhanced reabsorption in the proximal tubule that limits delivery to the loop, or an adaptive increase in reabsorption in the downstream distal tubule and collecting ducts that offsets ongoing blockade of Na+ reabsorption in the loop of Henle. These provide rationales for novel strategies including the concurrent use of diuretics that block these nephron segments and even sequential nephron blockade with multiple diuretics and aquaretics combined in severely diuretic-resistant patients with heart failure.

A narrative review of pharmacologic de-resuscitation in the critically ill

Despite evidence highlighting harms of fluid overload, minimal guidance exists on counteraction via utilization of diuretics in the de-resuscitation phase. While diuretics have been shown to decrease net volume and improve clinical outcomes in the critically ill, a lack of standardization surrounding selection of diuretic regimen or monitoring of de-resuscitation exists. Current monitoring parameters of de-resuscitation often rely on clinical signs of fluid overload, end organ recovery and other biochemical surrogate markers which are often deemed unreliable. The majority of evidence suggests that achieving a net-negative fluid balance within 72 h after shock resolution may be of benefit; however, approaches to such goal are uncertain. Loop diuretics are a widely available type of diuretic for removal of volume in patients with sufficient kidney function, with the potential for adjunct diuretics in special circumstances. At present, administration of diuretics within the broad critically ill population fails to find uniformity and often efficacy. Given the lack of randomized controlled trials in this susceptible population, we aim to provide a thorough therapeutic understanding of diuretic pharmacotherapy which is necessary in order to achieve desired goal of fluid balance and improve overall outcomes.

Diuretic Resistance in Heart Failure

Decompensated heart failure accounts for approximately 1 million hospitalizations in the United States annually, and this number is expected to increase significantly in the near future. Diuretics provide the initial management in most patients with fluid overload. However, the development of diuretic resistance remains a significant challenge in the treatment of heart failure. Due to the lack of a standard definition, the prevalence of this phenomenon remains difficult to determine, with some estimates suggesting that 25-30% of patients with heart failure have diuretic resistance. Certain characteristics, including low systolic blood pressures, renal impairment, and atherosclerotic disease, help predict the development of diuretic resistance. The underlying pathophysiology is likely multifactorial, with pharmacokinetic alterations, hormonal dysregulation, and the cardiorenal syndrome having significant roles. The therapeutic approach to this common problem typically involves increases in the diuretic dose and/or frequency, sequential nephron blockade, and mechanical fluid movement removal with ultrafiltration or peritoneal dialysis. Paracentesis is potentially useful in patients with intra-abdominal hypertension.

Spot urinary sodium in acute decompensation of advanced heart failure and dilutional hyponatremia: insights from DRAIN trial

BACKGROUND

Diuretic resistance portends a poor prognosis in acute heart failure, especially in advanced stages. Early identification of a poor response to diuretics may help to improve treatment and outcomes. Spot natriuresis (UNa⁺) at 2 h from the start of intravenous furosemide has been proposed as an early indicator of diuretic response. Our paper aimed to determine the role of early natriuresis in patients hospitalized with advanced chronic heart failure (ACHF) and high risk of diuretic resistance.

METHODS AND RESULTS

We performed a sub-analysis of the DRAIN trial, a randomized clinical trial on 80 patients with acute decompensation of ACHF (NYHA IV, EF ≤ 30%) with low systolic blood pressure (≤ 110 mmHg) and dilutional hyponatremia (sodium ≤ 135 mMol/L) at admission. Patients were divided into two groups according to spot urinary sodium excretion (high: UNa⁺  > 50 or low: ≤ 50 mEq/L) at 2 h from furosemide administration. Twenty-eight patients (35%) showed a low natriuretic response. As compared to the other patients, this group showed lower daily urinary output (2275 ± 790 vs 3849 ± 2034 mL, p < 0.001), lower body weight reduction after 48 h (1.55 ± - 1.66 vs - 3.55 ± - 2.93 kg, p < 0.001), higher incidence of worsening renal function (32% vs 10%, p 0.02) and increasing rather than reducing NT-proBNP at 72 h (p 0.02).

CONCLUSIONS

In patients with ACHF and dilutional hyponatremia, low natriuresis after furosemide is an early marker of poor diuretic response and correlates with higher NT-proBNP and higher incidence of worsening renal function at 72 h.

Old and New Drugs for Treatment of Advanced Heart Failure

BACKGROUND

Advanced heart failure (HF) is a progressive disease with high mortality and limited medical therapeutic options. Long-term mechanical circulatory support and heart transplantation remain goldstandard treatments for these patients; however, access to these therapies is limited by the advanced age and multiple comorbidities of affected patients, as well as by the limited number of organs available.

METHODS

Traditional and new drugs available for the treatment of advanced HF have been researched.

RESULTS

To date, the cornerstone for the treatment of patients with advanced HF remains water restriction, intravenous loop diuretic therapy and inotropic support. However, many patients with advanced HF experience loop diuretics resistance and alternative therapeutic strategies to overcome this problem have been developed, including sequential nephron blockade or use of the hypertonic saline solution in combination with high-doses of furosemide. As classic inotropes augment myocardial oxygen consumption, new promising drugs have been introduced, including levosimendan, istaroxime and omecamtiv mecarbil. However, pharmacological agents still remain mainly short-term or palliative options in patients with acute decompensation or excluded from mechanical therapy.

CONCLUSION

Traditional drugs, especially when administered in combination, and new medicaments represent important therapeutic options in advanced HF. However, their impact on prognosis remains unclear. Large trials are necessary to clarify their therapeutic potential and prognostic role in these fragile patients.

Prevalence and outcome of diuretic resistance in heart failure

Diuretic resistance (DR) is common in patients with decompensated heart failure (HF), and is associated with adverse outcomes. To determine the prevalence of DR and its impact on survival among patients with decompensated HF, we prospectively evaluated the prevalence and influence on prognosis of DR (defined as persistent congestion despite ≥ 80 mg of furosemide per day) in a cohort of elderly patients from the Spanish HF registry (RICA) admitted for an acute decompensation of HF. Patients with new-onset HF were excluded. From the global cohort of 2067 patients, 435 (21%; 95% CI 19.3%-22.7%) patients met criteria for DR. Patients with DR had more comorbidities (hypercholesterolemia, diabetes mellitus, valvular disease, chronic kidney disease, and cancer) and a worse functional status compared to patients without DR. In addition, patients with DR had a higher proportion of ischemic etiology, more advanced functional class and lower left ventricular ejection fraction values. After 1 year of follow-up, all-cause mortality was higher in patients with DR with an adjusted hazard ratio of 1.37 (95% CI 1.06-1.79; p = 0.018). The prevalence of DR in a cohort of elderly patients admitted for acute HF decompensation is 21%. DR is an independent predictor of 1-year mortality.

Acetazolamide to increase natriuresis in congestive heart failure at high risk for diuretic resistance

AIMS

To investigate the effects of acetazolamide on natriuresis, decongestion, kidney function and neurohumoral activation in acute heart failure (AHF).

METHODS AND RESULTS

This prospective, two-centre study included 34 AHF patients on loop diuretics with volume overload. All had a serum sodium concentration < 135 mmol/L and/or serum urea/creatinine ratio > 50 and/or an admission serum creatinine increase of > 0.3 mg/dL compared to baseline. Patients were randomised towards acetazolamide 250-500 mg daily plus bumetanide 1-2 mg bid vs. high-dose loop diuretics (bumetanide bid with daily dose twice the oral maintenance dose). The primary endpoint was natriuresis after 24 h. Natriuresis after 24 h was similar in the combinational treatment vs. loop diuretic only arm (264 ± 126 vs. 234 ± 133 mmol; P = 0.515). Loop diuretic efficiency, defined as natriuresis corrected for loop diuretic dose, was higher in the group receiving acetazolamide (84 ± 46 vs. 52 ± 42 mmol/mg bumetanide; P = 0.048). More patients in the combinational treatment arm had an increase in serum creatinine levels > 0.3 mg/dL (P = 0.046). N-terminal pro-B-type natriuretic peptide reduction and peak neurohumoral activation within 72 h were comparable among treatment arms. There was a non-significant trend towards lower all-cause mortality or heart failure readmissions in the group receiving acetazolamide with low-dose loop diuretics vs. high-dose loop diuretic monotherapy (P = 0.098).

CONCLUSION

Addition of acetazolamide increases the natriuretic response to loop diuretics compared to an increase in loop diuretic dose in AHF at high risk for diuretic resistance.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01973335.

Renal insufficiency in acute heart failure: old habits we need to let go?

Heart failure and renal insufficiency often coexist in the same patient. Customarily, this condition is described as ‘cardio-renal syndrome’. In this situation mortality increases significantly as the renal dysfunction worsen. Treating these patients is challenging, due to their instability (congestion needs to be controlled, while maintaining, or not worsening, organ perfusion), making in-hospital and mid-term mortality hard to improve. Congestion represent the key characteristic of this syndrome, and its treatment is far from been standardized, considering that the condition represent, still, the first cause of re-hospitalization for these patients. Present treatment should be modified, because barely accounts for renal physiology and is responsible for ‘resistance to diuretics’, which eventually becomes iatrogenic, and non ‘sodium-dependent’ hyponatraemia. It is then important to emphasize the importance of the ‘sequential nephron blockade’, to decrease the number of ‘non-responder’ to diuretics, and the possible role of the ‘acquaretics’.

The use of diuretics in heart failure with congestion - a position statement from the Heart Failure Association of the European Society of Cardiology

The vast majority of acute heart failure episodes are characterized by increasing symptoms and signs of congestion with volume overload. The goal of therapy in those patients is the relief of congestion through achieving a state of euvolaemia, mainly through the use of diuretic therapy. The appropriate use of diuretics however remains challenging, especially when worsening renal function, diuretic resistance and electrolyte disturbances occur. This position paper focuses on the use of diuretics in heart failure with congestion. The manuscript addresses frequently encountered challenges, such as (i) evaluation of congestion and clinical euvolaemia, (ii) assessment of diuretic response/resistance in the treatment of acute heart failure, (iii) an approach towards stepped pharmacologic diuretic strategies, based upon diuretic response, and (iv) management of common electrolyte disturbances. Recommendations are made in line with available guidelines, evidence and expert opinion.

Editor's Choice-Diuretic resistance in acute heart failure

Diuretic resistance is a powerful predictor of adverse outcome in acute heart failure (AHF), irrespectively of underlying glomerular filtration rate. Metrics of diuretic efficacy such as natriuresis, urine output, weight loss, net fluid balance, or fractional sodium excretion, differ in their risk for measurement error, convenience, and biological plausibility, which should be taken into account when interpreting their results. Loop diuretic resistance in AHF has multiple causes including altered drug pharmacokinetics, impaired renal perfusion and effective circulatory volume, neurohumoral activation, post-diuretic sodium retention, the braking phenomenon and functional as well as structural adaptations in the nephron. Ideally, these mechanisms should guide specific treatment decisions with the goal of achieving complete decongestion. Therefore, volume overload needs to be identified correctly to avoid poor diuretic response due to electrolyte depletion or dehydration. Next, renal perfusion should be optimised if possible and loop diuretics should be prescribed above their threshold dose. Addition of thiazide-type diuretics should be considered when a progressive decrease in loop diuretic efficacy is observed with prolonged use (i.e., the braking phenomenon). Furthermore, thiazide-type diuretics are a useful addition in patients with low glomerular filtration rate. However, they limit free water excretion and are relatively contraindicated in cases of hypotonic hyponatremia, where acetazolamide is the better option. Finally, ultrafiltration should be considered in patients with refractory diuretic resistance as persistent volume overload after decongestive treatment is associated with worse outcomes. Whether more upfront use of any of these individually tailored decongestion strategies is superior to monotherapy with loop diuretics remains to be shown by adequately powered randomised clinical trials.

Acetazolamide as Add-on Diuretic Therapy in Exacerbations of Chronic Heart Failure: a Pilot Study

Background

Congestion is the main cause of morbidity in patients with heart failure. Treatment of fluid overload is often challenging in everyday clinical practice.

Objective

The aim of this study was to determine the diuretic effect of acetazolamide in patients with exacerbations of chronic heart failure, in addition to their stable diuretic therapy.

Methods

This was a single-center, unblinded study. Patients hospitalized with chronic heart failure exacerbations, with left ventricular ejection fraction (EF) < 50% and signs of volume overload, with a stable dose of diuretics anticipated by the attending physician over the next 4 days, were considered eligible for the study. On day 1, patients were randomized to receive acetazolamide orally, once daily (dose-adjusted to body weight) or no treatment (control group) as add-on diuretic therapy, on days 2 and 3. Diuresis, natriuresis, fluid balance, and symptoms were assessed daily, up to day 4.

Results

Twenty patients (mean ± standard deviation age 72 ± 11.6 years; 85% men; mean EF 33.8 ± 11.4%; mean N-terminal pro-B-type natriuretic peptide 8064 ± 5593 pg/mL; mean intravenous furosemide dose 105 ± 55 mg) were enrolled. Diuresis, natriuresis, fluid balance, and symptoms were stable on days 1–4 in the control group. An increase in diuresis and natriuresis, and a greater change in fluid balance after administration of acetazolamide, were observed in patients randomized to acetazolamide. On day 4, there was a significant difference in fluid balance between the acetazolamide and control groups (−666 ± 1194 mL vs. +332 ± 705 mL; p = 0.035), and dyspnea was lower in patients receiving acetazolamide (visual scale, p < 0.001; 5-point Likert scale, 1.444 vs. 2.222; p = 0.04)

Conclusions

In this pilot study, the addition of acetazolamide to the background diuretic regimen in patients with chronic heart failure exacerbations produced an additional diuretic effect and alleviation of dyspnea.

Pharmacologic Approaches to Electrolyte Abnormalities in Heart Failure

Electrolyte abnormalities are common in heart failure and can arise from a variety of etiologies. Neurohormonal activation from ventricular dysfunction, renal dysfunction, and heart failure medications can perturb electrolyte homeostasis which impact both heart failure-related morbidity and mortality. These include disturbances in serum sodium, chloride, acid-base, and potassium homeostasis. Pharmacological treatments differ for each electrolyte abnormality and vary from older, established treatments like the vaptans or acetazolamide, to experimental or theoretical treatments like hypertonic saline or urea, or to newer, novel agents like the potassium binders: patiromer and zirconium cyclosilicate. Pharmacologic approaches range from limiting electrolyte intake or directly repleting the electrolyte, to blocking or promoting their resorption, and to neurohormonal antagonism. Because of the prevalence and clinical impact of electrolyte abnormalities, understanding both the older and newer therapeutic options is and will continue to be necessity for the management of heart failure.

A perspective on diuretic resistance in chronic congestive heart failure

Chronic congestive heart failure (CHF) is a complex disorder characterized by inability of the heart to keep up the demands on it, followed by the progressive pump failure and fluid accumulation. Although the loop diuretics are widely used in heart failure (HF) patients, both pharmacodynamic and pharmacokinetic alterations are thought to be responsible for diuretic resistance in these patients. Strategies to overcome diuretic resistance include sodium intake restriction, changes in diuretic dose and route of administration and sequential nephron diuretic therapy. In this review, we discuss the definition, prevalence, mechanism of development and management strategies of diuretic resistance in HF patients.

Management of Congestion and Diuretic Resistance in Heart Failure

We present the case of a patient with heart failure and severe congestion who was responding poorly to diuretic therapy. We discuss the key problems concerning the pathophysiology and bedside therapeutic approach to congestion and fluid overload in this clinical setting, and we give practical suggestions to overcome congestion, especially in the setting of diuretic resistance and worsening renal function. We conclude that the application of key pharmacokinetic and pharmacodynamic principles of diuretic therapy, along with in-depth knowledge of the pathophysiology of heart failure, still represent the cornerstones for a correct approach to decongestive therapy in these patients.

Management of Cardio-Renal Syndrome and Diuretic Resistance

OPINION STATEMENT

Diuretic resistance in acute heart failure has emerged as a powerful predictor of adverse outcome, which is often independent of underlying glomerular filtration rate (GFR). Metrics of diuretic efficacy differ in their accuracy, convenience, and biological plausibility, which should be taken into account when interpreting their results. Loop diuretic efficacy depends on adequate delivery of both the pharmacological agent itself and its substrate (i.e., sodium chloride) to the loop diuretic site of action at the luminal side of the thick ascending limb of Henle's loop. This requires an adequate dosing strategy, with higher doses needed when GFR is low. Importantly, the kidneys are able only to regulate the effective circulatory volume. Thus, specific problems of intravascular volume depletion and poor cardiac output with impaired renal perfusion should be addressed. Addition of thiazide-type diuretics should be considered when a progressive decrease in loop diuretic efficacy is observed with prolonged use (i.e., the braking phenomenon). Furthermore, thiazide-type diuretics are a useful addition in patients with low GFR to maximally boost fractional sodium excretion when nephron perfusion is poor. However, thiazide-type diuretics limit free water excretion and should be withheld in cases of hypotonic hyponatremia. Mineralocorticoid receptor antagonists (MRA) and acetazolamide are interesting options to increase loop diuretic efficacy, but further study is needed to assess whether improved diuretic efficacy also translates into clinical outcome benefits. Finally, ultrafiltration should be considered in patients with refractory diuretic resistance as persistent volume overload after decongestive treatment is associated with worse outcomes. Whether more upfront use of individually tailored ultrafiltration is superior to pharmacological therapy remains to be shown by adequately powered randomized clinical trials.

Volume control in treatment-resistant congestive heart failure: role for peritoneal dialysis

Chronic congestive heart failure (HF) has a rising prevalence and increasing impact on health care systems. Current treatment consists of diuretics, renin-angiotensin-aldosterone system blockers, and restriction of salt and fluids. This strategy is often hampered by a drop in effective circulating volume and hence renal perfusion and function, triggering harmful counter regulatory mechanisms. Slow ultrafiltration by peritoneal dialysis (PD) might be an effective treatment strategy to relieve fluid overload without compromising cardiac output and thereby renal function. In this review, we discuss the (patho)physiological mechanisms of the cardiorenal interaction and the current literature on PD strategies in congestive HF.

Fractional excretion of sodium and its association with prognosis of decompensated heart failure patients

INTRODUCTION

Diuretic resistance is a common problem in congestive heart failure patients. It has been defined clinically but can be defined objectively in terms of fractional excretion of sodium (FENa).

AIM

Aim of the study was to find out the association of FENa with prognosis of decompensated heart failure patients.

MATERIALS AND METHODS

One hundred and seventy eligible patients with a primary diagnosis of decompensated heart failure were enrolled and patients were categorized into two groups on the basis of baseline FENa- Group A (65 patients) with diuretic resistance with FENa <0.2% and Group B (105 patients) sensitive to diuretics with FENa ≥0.2%. The patients were followed-up during the hospital stay for the time taken for improvement from NYHA functional class IV to class II. They were followed telephonically at 30 days post admission for all cause mortality.

RESULT

The mean time taken to improve from NYHA functional class IV to class II were 146 hours for FENa<.2% and 60 h for FENa≥0.2% (p<0.0001). There was a fair negative correlation between FENa and time taken for improvement from NYHA functional class IV to class II with correlation coefficient being -0.4842. Multiple linear regression analysis showed FENa (standardized "B" is -0.480, p<0.001) and LVEF (standardized "B" is -0.182, p=0.007) as significant predictors of time taken for improvement from NYHA functional class IV to class II. The 30 days all cause mortality was significantly associated with level of Fena (p <0.001) and was inversely proportional.

CONCLUSION

CHF patients with FENa <0.2% takes longer time to recover from NYHA functional class IV to class II. 30 days all cause mortality was also significantly higher among CHF patients with FENa <0.2%.Measuring baseline FENa and regulating diuretic dose accordingly at admission to hospital may probably improve the prognosis of CHF patients.

Diuretic response in acute heart failure-pathophysiology, evaluation, and therapy

The administration of loop diuretics to achieve decongestion is the cornerstone of therapy for acute heart failure. Unfortunately, impaired response to diuretics is common in these patients and associated with adverse outcomes. Diuretic resistance is thought to result from a complex interplay between cardiac and renal dysfunction, and specific renal adaptation and escape mechanisms, such as neurohormonal activation and the braking phenomenon. However, our understanding of diuretic response in patients with acute heart failure is still limited and a uniform definition is lacking. Three objective methods to evaluate diuretic response have been introduced, which all suggest that diuretic response should be determined based on the effect of diuretic dose administered. Several strategies have been proposed to overcome diuretic resistance, including combination therapy and ultrafiltration, but prospective studies in patients who are truly unresponsive to diuretics are lacking. An enhanced understanding of diuretic response should ultimately lead to an improved, individualized approach to treating patients with acute heart failure.

Diuretic Therapy in Heart Failure - Current Approaches

The use of diuretics is common in patients with heart failure (HF), to relieve the congestive symptoms of HF. Although they are widely used, there are limited data on their ability to modulate HF-related morbidity and mortality. Diuretic efficacy may be limited by adverse neurohormonal activation and by 'congestion-like' symptoms. Diuretics are an extremely useful and varied class of agent for the management of hypervolaemic states. This review summarises the basic features of diuretics, including their mechanism of action, indications and adverse effects in heart failure.

New insights into combinational drug therapy to manage congestion in heart failure

Congestion is the most important contributor to morbidity and mortality in heart failure. In patients without congestion, maintaining a neutral sodium balance is imperative to prevent evolving volume overload. Adequate use of neurohumoral blockers, in combination with dietary sodium restriction, is essential and may preclude the need for maintenance diuretic therapy. If volume overload still prevails, loop diuretics remain the mainstay treatment to reduce excessive extracellular volume. However, combinational drug therapy might offer a more attractive alternative to achieve a balanced natriuresis, instead of further uptitration of loop diuretics. Importantly, elevated cardiac filling pressures may be caused by volume misdistribution and impaired venous capacitance, rather than absolute volume overload. Vasodilator therapy to unload the heart, increase venous capacitance, and lower arterial impedance might be interesting in such cases. This review offers a practical approach into current and potential future pharmacologic therapies for managing congestion, focusing on combinational and targeted therapy.

The kidney in congestive heart failure: 'are natriuresis, sodium, and diuretics really the good, the bad and the ugly?'

This review discusses renal sodium handling in heart failure. Increased sodium avidity and tendency to extracellular volume overload, i.e. congestion, are hallmark features of the heart failure syndrome. Particularly in the case of concomitant renal dysfunction, the kidneys often fail to elicit potent natriuresis. Yet, assessment of renal function is generally performed by measuring serum creatinine, which has inherent limitations as a biomarker for the glomerular filtration rate (GFR). Moreover, glomerular filtration only represents part of the nephron's function. Alterations in the fractional reabsorptive rate of sodium are at least equally important in emerging therapy-refractory congestion. Indeed, renal blood flow decreases before the GFR is affected in congestive heart failure. The resulting increased filtration fraction changes Starling forces in peritubular capillaries, which drive sodium reabsorption in the proximal tubules. Congestion further stimulates this process by augmenting renal lymph flow. Consequently, fractional sodium reabsorption in the proximal tubules is significantly increased, limiting sodium delivery to the distal nephron. Orthosympathetic activation probably plays a pivotal role in those deranged intrarenal haemodynamics, which ultimately enhance diuretic resistance, stimulate neurohumoral activation with aldosterone breakthrough, and compromise the counter-regulatory function of natriuretic peptides. Recent evidence even suggests that intrinsic renal derangements might impair natriuresis early on, before clinical congestion or neurohumoral activation are evident. This represents a paradigm shift in heart failure pathophysiology, as it suggests that renal dysfunction-although not by conventional GFR measurements-is driving disease progression. In this respect, a better understanding of renal sodium handling in congestive heart failure is crucial to achieve more tailored decongestive therapy, while preserving renal function.

Role of diuretics and ultrafiltration in congestive heart failure

Volume overload in heart failure (HF) results from neurohumoral activation causing renal sodium and water retention secondary to arterial underfilling. Volume overload not only causes signs and symptoms of congestion, but can impact myocardial remodeling and HF progression. Thus, treating congestion is a cornerstone of HF management. Loop diuretics are the most commonly used drugs in this setting. However, up to 30% of the patients with decompensated HF present with loop-diuretic resistance. A universally accepted definition of loop diuretic resistance, however, is lacking. Several approaches to treat diuretic-resistant HF are available, including addition of distal acting thiazide diuretics, natriuretic doses of mineralocorticoid receptor antagonists (MRAs), or vasoactive drugs. Slow continuous veno-venous ultrafiltration is another option. Ultrafiltration, if it is started early in the course of HF decompensation, may result in prominent decongestion and a reduction in re-hospitalization. On the other hand, ultrafiltration in HF patients with worsening renal function and volume overload after aggressive treatment with loop diuretics, failed to show benefit compared to a stepwise pharmacological approach, including diuretics and vasoactive drugs. Early detection of congested HF patients for ultrafiltration treatment might improve decongestion and reduce readmission. However, the best patient characteristics and best timing of ultrafiltration requires further evaluation in randomized controlled studies.

Sequential nephron blockade versus sequential renin-angiotensin system blockade in resistant hypertension: a prospective, randomized, open blinded endpoint study

OBJECTIVE

To compare two drug regimens to treat resistant hypertension.

METHODS

In a prospective, randomized, open blinded endpoint study, 167 patients with mean baseline daytime ambulatory blood pressure 135 mmHg or more and/or 85 mmHg or more, despite 4 weeks' treatment with irbesartan 300 mg/day, hydrochlorothiazide 12.5 mg/day and amlodipine 5 mg/day, were randomized to sequential nephron blockade (group 1, n = 85) or sequential renin-angiotensin system blockade (group 2, n = 82). First, spironolactone 25 mg/day in group 1 or ramipril 5 mg/day in group 2 were added for 4 weeks. Treatment was increased at weeks 4, 8 or 10 if home blood pressure was 135 mmHg or more and/or 85 mmHg or more by sequentially administering furosemide 20 mg/day, furosemide 40 mg/day and amiloride 5 mg/day in group 1, or ramipril 10 mg/day, bisoprolol 5 mg/day and bisoprolol 10 mg/day in group 2. The primary endpoint was change in systolic daytime ambulatory blood pressure at week 12.

RESULTS

At week 12, the mean between-group difference in daytime ambulatory blood pressure was 10/4 mmHg (95% confidence interval: 7-14/2-7; P < 0.001/P = 0.0014) in favour of the group 1. The blood pressure goal (daytime ambulatory blood pressure <135/85 mmHg) was achieved in 58% in the group 1 and 20% in the group 2 (P < 0.0001). Discontinuation for drug-related adverse events was low (group 1, n = 7; group 2, n = 6).

CONCLUSION

In patients with resistant hypertension, sequential nephron blockade induces a large and well tolerated reduction in blood pressure via a progressive increase in sodium depletion, and is more effective than sequential renin-angiotensin system blockade.