Changes in circulating norepinephrine with hemofiltration in advanced congestive heart failure

Fluid balance in heart failure

Fluid retention is a major determinant of symptoms in patients with heart failure (HF), and it is closely associated with prognosis. Hence, congestion represents a critical therapeutic target in this clinical setting. The first therapeutic strategy in HF patients with fluid overload is optimization of diuretic intervention to maximize water and sodium excretion. When diuretic therapy fails to relieve congestion, renal replacement therapy represents the only alternative option for fluid removal, as well as a way to restore diuretic responsiveness. On this background, the pathophysiology of fluid balance in HF is complex, with heart, kidney, and lung being deeply involved in volume regulation and management. Therefore, the interplay between these organs should be appreciated and considered when fluid overload in HF patients is targeted.

Hemofiltration in Heart Failure

In patients with severe congestive heart failure (CHF), removal of edema by hemofiltration is associated with significant clinical and hemodynamic improvement, correction of hyponatremia, restoration of urine output and diuretic responsiveness, and with a striking fall in neurohormonal activation. Through these effects, hemofiltration is able to interrupt the progression of CHF toward refractoriness, and to revert the clinical condition of CHF patients to a lower functional class.

Fluid refilling from the overhydrated interstitium is the major compensatory mechanism in the prevention of hypovolemia during hemofiltration.

Hemofiltration can also be beneficial in patients who have only moderate cardiac insufficiency (NYHA classes II and III) and in whom over-hydration is restricted to the pulmonary district significantly contributing to limiting patients functional capacity. In this setting, hemofiltration, differently from diuretics, is able to remove the increased lung water content and to improve clinical condition, exercise capacity and lung function.

Extracorporeal ultrafiltration for acute heart failure: patient selection and perspectives

Most patients presenting with acute heart failure (AHF) show signs and symptoms of fluid overload, which are closely associated with short-term and long-term outcomes. Ultrafiltration is an extremely appealing strategy for patients with AHF and concomitant overt fluid overload not fully responsive to diuretic therapy. However, although there are several theoretical beneficial effects associated with ultrafiltration, published reports have shown controversial findings. Differences in selection of the study population and in ultrafiltration indications and protocols, and high variability in the pharmacologic therapy used for the control group could explain some of these conflicting results. Here, we aimed to provide an overview on the current medical evidence supporting the use of ultrafiltration in AHF, with a special focus on the identification of potential candidates who may benefit the most from this therapeutic option.

Role of isolated ultrafiltration in the management of chronic refractory and acute decompensated heart failure

Chronic congestive heart failure (CHF) and acute decompensated heart failure (ADHF) refractory to medical therapy represent therapeutic challenges. In such patients, attempts to reduce pulmonary and systemic congestion frequently produce deterioration of renal function. In studies of patients with chronic severe CHF refractory to medical therapy (including loop diuretics), isolated ultrafiltration was frequently able to relieve congestive symptoms by precise removal of extracellular water and sodium, and in some cases was able to restore responsiveness to loop diuretics. Randomized controlled trials comparing isolated ultrafiltration and medical therapy (mainly loop diuretics) in patients with ADHF failed to demonstrate the superiority of isolated ultrafiltration over diuretic therapy with respect to renal function and mortality. Isolated ultrafiltration reduced length of hospital stay in several studies. At this time, there is insufficient evidence to support the use of isolated ultrafiltration as initial therapy of ADHF.

Continuous ultrafiltration in acute decompensated heart failure: current issues and future directions

Most patients hospitalized for acutely decompensated heart failure (ADHF) present with symptoms and signs of volume overload, which are also associated with high rates of death and re-hospitalization. Several studies have investigated the possible use of extracorporeal ultrafiltration in the management of ADHF, evaluating potential clinical benefits in terms of hospitalization and survival rates versus those of conventional diuretic therapy. Though ultrafiltration remains an extremely appealing therapeutic option for patients with AHDF, some of the most recent studies have reported conflicting results. Differences in the selection of study population, heterogeneity of the indications for the use of ultrafiltration, disparity in the ultrafiltration protocols, and high variability in the pharmacologic therapies used for the control group could explain some of these contradictory findings. The purpose of the present review is to provide an overview and an update on the mechanisms and clinical effects of ultrafiltration and on currently available evidence supporting its use in ADHF.

Ultrafiltration for congestive heart failure: the past and the present

PURPOSE OF REVIEW

To provide an overview on the most recent evidence for the use of extracorporeal and peritoneal ultrafiltration in heart failure, focusing on the major publications from the last few years.

RECENT FINDINGS

There have been several studies investigating the possible use of extracorporeal and peritoneal ultrafiltration in the management of acute and chronic heart failure. These trials have investigated the potential benefits and advantages of ultrafiltration over conventional medical therapy, in terms of clinical outcomes.

SUMMARY

Although ultrafiltration remains an extremely appealing therapeutic option for patients with heart failure and congestion, with several theoretical beneficial effects, some of the most recent studies have reported inconsistent findings. Differences in the selection of the study population, heterogeneity of the indications for use of ultrafiltration, variation in the ultrafiltration protocols, and high variability in the pharmacologic therapy used for the control group could explain some of these conflicting findings.

Extracorporeal ultrafiltration for heart failure: focus on organ cross talk and clinical trials

Despite major advances in pharmacological therapy and cardiac devices, heart failure patients continue to be frequently (re-)hospitalized with signs and symptoms of fluid overload. Diuretics improve the symptoms of fluid overload, but their effectiveness is reduced by a number of factors including excess salt intake, underlying chronic kidney disease, renal adaptation to their actions and neurohormonal activation. Ultrafiltration (UF) is a mechanical method of fluid removal with several potential advantages over diuretic-based conventional therapies: several recent studies have demonstrated favorable clinical response to UF therapy. Such studies have shown that removal of large amounts of isotonic fluid, in addition to relieving symptoms of congestion, can improve exercise capacity, reduce cardiac filling pressures, restore diuretic responsiveness, and portend a favorable effect on cardio-pulmonary, cardiorenal interactions, and neurohormonal hyperactivation. However, despite these proposed benefits, so far, no clinical study has yet been carried out to explore the impact of UF therapy on hard clinical endpoints such as long-term mortality. In this article, we review a number of mechanistic aspects of UF therapy, with particular emphasis on cardio-pulmonary and cardiorenal interactions, and revisit the results of more recent clinical trials in order to highlight the characteristics that can help identify patients who are more likely to benefit from this therapeutic modality.

Pathophysiology of cardiorenal syndrome in decompensated heart failure: role of lung-right heart-kidney interaction

Cardiorenal syndrome (CRS) is defined as an interaction of cardiac disease with renal dysfunction that leads to diuretic resistance and renal function worsening, mainly with heart failure (HF) exacerbation. Hemodynamic variables linking heart and kidney are renal blood flow (cardiac output) and perfusion pressure, i.e., the aortic - renal venous pressure gradient. CRS has traditionally been interpreted as related to defective renal perfusion and arterial underfilling and, more recently, to elevation in central venous pressure transmitted back to renal veins. Our suggestion is that in a setting where aortic pressure is generally low, due to heart dysfunction and to vasodrepressive therapy, the elevated central venous pressure (CVP) contributes to lower the renal perfusion pressure below the threshold of kidney autoregulation (≤80mm Hg) and causes renal perfusion to become directly pressure dependent. This condition is associated with high neurohumoral activation and preglomerular vasoconstriction that may preserve pressure, but may decrease filtration fraction and glomerular filtration rate and enhance proximal tubular sodium absorption. Thus, congestion worsens and drives the vicious cycle of further sodium retention and HF exacerbation. Lowering CVP by targeting the lung-right heart interaction that sustains elevated CVP seems to be a more rational approach rather than reducing intravascular volume. This interaction is crucial and consists of a cascade with stepwise development of pulmonary post-capillary hypertension, precapillary arteriolar hypertone, right ventricular overload and enlargement with tricuspid incompetence and interference with left ventricular filling (interdependence). The resultant CVP rise is transmitted to the renal veins, eventually drives CRS and leads to a positive feedback loop evolving towards HF refractoriness.

Treatment of congestion in heart failure with diuretics and extracorporeal therapies: effects on symptoms, renal function, and prognosis

In the United States and Europe, approximately 90% of heart failure hospitalizations are due to symptoms and signs of sodium and fluid excess. Congestion is associated with heart failure progression. Venous congestion, rather than a reduced cardiac output, may be the primary hemodynamic factor driving worsening renal function in patients with acutely decompensated heart failure. According to data from large national registries, approximately 40% of hospitalized heart failure patients are discharged with unresolved congestion, which may contribute to unacceptably high re-hospitalization rates. Diuretics reduce the symptoms and signs of fluid overload, but their effectiveness can be reduced by excess salt intake, underlying chronic kidney disease, renal adaptation to their action, and neurohormonal activation. In addition, the production of hypotonic urine limits the ability of loop diuretics to reduce total body sodium. Ultrafiltration is the mechanical removal of fluid from the vasculature. Hydrostatic pressure is applied to blood across a semipermeable membrane to separate isotonic plasma water from blood. Because solutes in blood freely cross the semipermeable membrane, fluid can be removed without causing significant changes in the serum concentration of electrolytes and other solutes. Relatively small, mostly single-center clinical studies of ultrafiltration have shown that removal of isotonic fluid may relieve symptoms of congestion and restore diuretic responsiveness in patients with diuretic resistance. These studies have also shown a favorable effect on neurohormonal activation. When compared with intravenous diuretics, ultrafiltration similarly changed dyspnea scores but reduced re-hospitalizations (28 of 87 patients (32%) versus 16 of 89 patients (18%), P < 0.037) in a randomized controlled trial of patients with decompensated heart failure. Future larger controlled clinical trials should evaluate further the effect of ultrafiltration on patients' outcomes, including survival.

Ultrafiltration in heart failure

Fluid overload is a key pathophysiologic mechanism underlying both the acute decompensation episodes of heart failure and the progression of the syndrome. Moreover, it represents the most important factor responsible for the high readmission rates observed in these patients and is often associated with renal function worsening, which by itself increases mortality risk. In this clinical context, ultrafiltration (UF) has been proposed as an alternative to diuretics to obtain a quicker relief of pulmonary/systemic congestion. This review illustrates technical issues, mechanisms, efficacy, safety, costs, and indications of UF in heart failure. The available evidence does not support the widespread use of UF as a substitute for diuretic therapy. Owing to its operative characteristics, UF cannot be expected to directly influence serum electrolyte levels, azotemia, and acid-base balance, or to remove high-molecular-weight substances (eg, cytokines) in clinically relevant amounts. Ultrafiltration should be used neither as a quicker way to achieve a sort of mechanical diuresis nor as a remedy for an inadequately prescribed and administered diuretic therapy. Instead, it should be reserved to selected patients with advanced heart failure and true diuretic resistance, as part of a more complex strategy aiming at an adequate control of fluid retention.

Ultrafiltration for congestive heart failure

Relief of congestive symptoms is a primary goal in treating heart failure. Ultrafiltration is a tool that can be used to safely remove sodium and water from whole blood at a controlled rate. Ultrafiltration decreases symptoms, relieves congestion, and improves hemodynamics, neurohormonal balance, and exercise capacity. This article describes the importance of congestion as a therapeutic target in heart failure and outlines the development of ultrafiltration as a treatment to address this important physiologic state.

Association of weight change with subsequent outcomes in patients hospitalized with acute decompensated heart failure

The association of weight loss achieved through various decongestive strategies with clinical outcomes in patients with acute decompensated heart failure (HF) is not well described. The aim of this study was to determine the relation between weight change during hospitalization and subsequent clinical events in patients with decompensated HF. Data from 433 patients hospitalized with advanced HF enrolled in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial were evaluated. The influence of change in weight during hospitalization to clinical outcomes (days alive out of the hospital in the first 6 months; death; death or rehospitalization; and death, rehospitalization, or cardiac transplantation) was evaluated. On average, patients lost approximately 3.6 kg during hospitalization. When categorized into 3 weight loss tertiles, those in the highest tertile were more likely to be older, women, and smokers, with higher body weights, previous percutaneous coronary interventions, baseline heart rates, and brain natriuretic peptide and blood urea nitrogen values but lower ejection fractions and peak oxygen consumption. No significant differences were observed between weight change and any in-hospital or follow-up events (days well: hazard ratio 0.995, 95% confidence interval 0.975 to 1.016; 180-day death: hazard ratio 1.012, 95% confidence interval 0.969 to 1.057; death or rehospitalization at 180 days: hazard ratio 1.014, 95% confidence interval 0.990 to 1.038). In conclusion, weight loss in patients with acute decompensated HF during hospitalization was not related to clinical end points. These data challenge the merit of using weight as a surrogate end point for more important clinical events (i.e., death and/or rehospitalization) in patients with HF in the design of treatment strategies for novel therapeutic agents in randomized controlled clinical trials.

Ultrafiltration in the management of heart failure

PURPOSE OF REVIEW

Congestion causes the majority of hospitalizations for heart failure and contributes to heart failure progression and mortality. Intravenous loop diuretics reduce the signs and symptoms of congestion. Loop diuretics, however, may be associated with increased morbidity and mortality because of deleterious effects on neurohormonal activation, electrolyte balance, and cardiac and renal function. Ultrafiltration, an alternative method of sodium and water removal, safely improves hemodynamics in heart failure patients.

RECENT FINDINGS

The Ultrafiltration versus Intravenous Diuretics for Patients Hospitalized for Acute Decompensated Heart Failure trial has recently shown that among 200 volume overloaded heart failure patients randomized to ultrafiltration or intravenous diuretics, 48 h weight (P = 0.001) and net fluid loss (P = 0.001) were greater in the ultrafiltration group. Dyspnea scores were similar. At 90 days, the ultrafiltration group had fewer heart failure rehospitalizations/patient (P = 0.022) and patients presenting for unscheduled visits (21 vs. 44%; P = 0.009). No serum creatinine differences occurred between the groups.

SUMMARY

In decompensated heart failure, ultrafiltration safely produces greater weight and fluid loss than intravenous diuretics, reduces rehospitalization rates for heart failure and is an effective alternative therapy.

The role of ultrafiltration in the management of heart failure

In the United States, 90% of one million annual hospitalizations for heart failure are due to symptoms of volume overload. Hypervolemia contributes to heart failure progression and mortality. Treatment guidelines recommend that therapy for patients with heart failure be aimed at achieving euvolemia. Intravenous loop diuretics induce a rapid diuresis that reduces lung congestion and dyspnea. However, loop diuretics' effectiveness declines with repeated exposure. Unresolved congestion may contribute to high re-hospitalization rates. Furthermore, loop diuretics may be associated with increased morbidity and mortality due to deleterious effects on neurohormonal activation, electrolyte balance, and cardiac and renal function. Ultrafiltration is an alternative method of sodium and water removal, which safely improves hemodynamics in patients with heart failure. Application of this technology has been limited by the need for high flow rates, large extracorporeal blood volumes, and large-bore central venous catheters. A modified ultrafiltration device has overcome these limitations. Ultrafiltration may be a safe and effective alternative to intravenous diuretics in the treatment of decompensated heart failure.

Continuous Renal Replacement Therapy for Management of Overhydration in Heart Failure

An estimated 4.8 million Americans are diagnosed with heart failure. Of those, 5% to 10% meet criteria for the refractory state of the disease. While therapeutic interventions continue to evolve with the changing conceptualization of heart failure pathophysiology, overhydration and its deleterious sequelae remain a problem for those in the refractory state. The incidence of heart failure continues to rise in older individuals. As baby-boomers age across America, greater focus on new, more effective therapies must be considered for treatment of this disease. Continuous renal replacement therapy (CRRT) is one such treatment. The gentle removal of fluid and metabolites while maintaining electrolyte balance helps reduce the effects of overhydration in patients with heart failure. Increasing use of the therapy in the refractory state of heart failure is generating support for early initiation as it continues to demonstrate positive effects. Reduction in edema, attenuation of the sympathoadrenal cascade, and improved respiratory status have all been documented using the therapy. The intent of this article is to provide information for advanced practice nurses and direct care providers regarding CRRT for the treatment of heart failure refractory to typical therapy.

Continuous renal replacement therapy: opinions and evidence

Continuous arteriovenous haemofiltration (CAVH) is the first example of continuous renal replacement therapy (CRRT). CAVH was first applied for the treatment of diuretic unresponsive fluid overload. Subsequently, CRRT has undergone a remarkable growth, and it is now performed with pump technology (CVVH) and via double-lumen central venous catheters. In many intensive care units, especially in Australia and in Europe, CRRT has become the dominant, if not exclusive, form of artificial renal support. Continuous haemofiltration is now used beyond the original indications of blood purification, for the treatment of certain drug intoxications, for severe cardiac failure, for volume control during, after cardiopulmonary bypass, and to decrease the toxicity of chemotherapy. Furthermore, there is strong ongoing research into its role or that of derived techniques as possible adjuvant therapies during severe sepsis. Despite its large use, the current state of CRRT is surrounded by some controversies, and an effort should be made to give a dispassionate distillation of the literature for a final common definition of what is based on opinions and what carries sufficient evidence.

Continuous haemofiltration in the intensive care unit

Continuous renal replacement therapy (CRRT) was first described in 1977 for the treatment of diuretic-unresponsive fluid overload in the intensive care unit (ICU). Since that time this treatment has undergone a remarkable technical and conceptual evolution. It is now available in most tertiary ICUs around the world and has almost completely replaced intermittent haemodialysis (IHD) in some countries. Specially made machines are now available, and venovenous therapies that use blood pumps have replaced simpler techniques. Although, it remains controversial whether CRRT decreases mortality when compared with IHD, much evidence suggests that it is physiologically superior. The use of CRRT has also spurred renewed interest in the broader concept of blood purification, particularly in septic states. Experimental evidence suggests that this is a promising approach to the management of septic shock in critically ill patients. The evolution and use of CRRT is likely to continue and grow over the next decade.

The noradrenaline plasma concentration and its gradient across the lung

BACKGROUND

We investigated the lung contribution to circulating noradrenaline (NA) homeostasis. Evaluation of the transpulmonary NA gradient, related to the NA amount entering the lungs, is potentially important, mainly regarding clinical conditions, such as congestive heart failure (CHF), that are associated with excessive circulating NA.

MATERIALS AND METHODS

15 moderate (group 1) and 15 severe (group 2) CHF patients, and 10 normal individuals had determination of NA transpulmonary gradient in the baseline and during rise (exercise, in normals and group 1) or fall (withdrawal from plasma by ultrafiltration, in group 2) of plasma NA.

RESULTS

NA gradient (pg mL(-1)) at rest was 30 +/- 3 in normals, 21 +/- 6 in group 1 and 5 +/- 8 in group 2. Increase of NA concentration in the mixed venous blood with exercise was paralleled by depression of the transpulmonary gradient. Pulmonary arteriovenous difference disappeared when NA entering the lungs averaged 1300 pg mL(-1). In group 2, ultrafiltration lowered NA in the mixed venous blood from 1225 +/- 213 to 718 +/- 182, which caused transpulmonary gradient to increase from 5 +/- 8 to 22 +/- 9.

CONCLUSIONS

Transpulmonary gradient of NA diminishes when NA entering the lungs increases, and 1300 pg mL(-1) in the pulmonary artery is, both in patients and normal subjects, the level at which gradient disappears; which likely reflects cessation of NA uptake or achievement of a balance between lung uptake and production. This may have physiological and pathological implications.

Cardiac afferents and neurohormonal activation in congestive heart failure

Cardiac chambers have afferent connections to the brainstem and to the spinal cord. Vagal afferents mediate depressor responses and become activated by volume expansion, increased myocardial contractility and atrial natriuretic factor. Sympathetic afferents, on the contrary, are activated by metabolic mediators, myocardial ischemia and cardiac enlargement. These opposite behaviors may lead to activation or suppression of the sympathetic nervous system and of the renin-angiotensin-aldosterone system. As cardiac diseases progress, the heart dilates, plasma norepinephrine increases, atrial natriuretic factor is released and the renin-angiotensin-aldosterone system is suppressed to maintain water and sodium excretion. This dissociation of the neurohormonal profile of cardiac patients, may be explained by coactivation of sympathetic afferents, by cardiac dilatation, and of vagal afferents by atrial natriuretic factor. In more advanced stages, atrial natriuretic factor suppression of the renin-angiotensin-aldosterone system is overridden by overt sympathetic activation and sodium and water retention ensues. Digitalis, angiotensin-converting enzyme inhibitors and beta-blockers selectively decrease cardiac adrenergic drive. A common mechanism of action, to all three groups of drugs, would be attenuation of sympathetic afferents and partial normalization of vagal afferents. Consequently, heart size and cardiac afferents emerge as the key factors to understand the pathophysiology and treatment of the syndrome of congestive heart failure.

Non-renal indications for continuous renal replacement therapy

While there is clear support for the use of continuous renal replacement therapy (CRRT) in critically ill acute renal failure patients, there are other illnesses without renal involvement where CRRT might be of value. These include sepsis and other inflammatory syndromes such as acute respiratory distress syndrome (ARDS) and cardiopulmonary bypass where removal of inflammatory mediators by hemofiltration is hypothesized to improve outcome. Adsorption appears to be the predominant mechanism of mediator elimination. However, the observed hemodynamic improvement can, at least partially, be attributed to a reduction of body temperature or to fluid removal, and the evidence for a clinically important removal of proinflammatory cytokines remains limited. Continuous and therefore smooth fluid removal may improve organ function in ARDS, after surgery with cardiopulmonary bypass, and in patients with refractory congestive heart failure. Continuous removal of endogenous toxins, eventually combined with intermittent hemodialysis, is probably beneficial in inborn errors of metabolism, severe lactic acidosis, or tumor lysis syndrome.

Influence of ACE Inhibition on Fluid Metabolism in Chronic Heart Failure and Its Pathophysiologic Relevance

BACKGROUND: In congestive heart failure with water retention, subtraction of body fluid by ultrafiltration causes greater diuresis and clinical improvement in patients who are angiotensin-converting enzyme (ACE)-inhibited, suggesting an influence of ACE inhibitors on fluid metabolism. METHODS AND RESULTS: Patients with moderate congestive heart failure were subjected to ultrafiltration (around 2000 mL) and followed up for 3 months. Usual outpatient therapy, consisting of digoxin, furosemide, and ACE inhibitors (18 patients, group A) and of digoxin and furosemide only (18 patients, group B), was continued throughout the trial. Hemodynamics, renal function, body fluid and electrolytes, plasma norepinephrine, renin activity, aldosterone, and plasma volume were monitored. At 30 and 90 days after ultrafiltration, hormones, renal function, functional capacity (based on cardiopulmonary tests), and extravascular lung water (chest radiograph score) were determined. Soon after ultrafiltration, body weight, plasma volume, and diuresis were reduced (hypovolemia) and hormones were raised (reaction to hypovolemia). In the next 4 days, all these variables reverted to the pre-ultrafiltration values in group B; in group A diuresis and plasma volume recovered, body weight was still reduced, and hormones became lower than baseline. These changes persisted in the next 3 months. An early reduction of extravascular lung water continued long term in group A only, associated with increase of exercise tolerance time and oxygen uptake and decrease of the dead space/tidal volume ratio. CONCLUSIONS: In congestive heart failure, ACE inhibition persistently prevented fluid accumulation once the excess of body fluid had been withdrawn with a nonpharmacologic method, resulting in sustained improvement in functional capacity. Reduction in circulating norepinephrine, aldosterone, and renin did not seem to be the cause but the consequence of this action, whose mechanisms remain undefined.

Outcome predictors of ultrafiltration in patients with refractory congestive heart failure and renal failure

This study is an attempt to identify predictors of outcome from the use of ultrafiltration (UF) in patients with refractory congestive heart failure (CHF) and renal failure. The authors studied 30 patients in NYHA functional class IV in whom UF was utilized in the management of refractory CHF. Patients were retrospectively divided into two groups according to their outcome. Group A included 12 patients who improved and survived hospital admission, and group B included 18 patients who did not respond and died shortly after UF. Clinical, hemodynamic, and laboratory data before UF were fairly comparable between both groups. Renal function and hemodynamic parameters were compared and analyzed within the same group and between both groups before and after UF. The mean age in group A was sixty-three +/- thirteen years while in group B it was seventy +/- eleven years (P < 0.005). A mean of 9.6 liters of fluid were removed from group A and 3.2 liters from group B (P < 0.001). Group A showed greater reduction in the mean values of right atrial pressure (P < 0.005) and pulmonary capillary wedge pressure (P < 0.05) after UF. Additionally, group A showed a significant decrease in their blood urea nitrogen (P < 0.05) and serum creatinine values (P < 0.05), in contradistinction to group B patients who showed a major increase in those values after UF. There was no significant change in the mean values of cardiac index, systemic vascular resistance, and pulmonary vascular resistance after UF. These findings suggest that younger age groups, greater fluid removal, as well as significant decreases in blood urea nitrogen, serum creatinine, and right atrial and pulmonary wedge pressures after UF, are associated with favorable outcome. Conversely, older age groups, less fluid removal, and rising blood urea nitrogen and serum creatinine levels after UF were associated with poor outcome.

Refractory Heart Failure: A Therapeutic Approach

Optimal “triple therapy” for patients with chronic congestive heart failure (CHF) includes diuretics, digoxin, and either angiotensin-converting enzyme inhibitors or hydralazine plus nitrates. Refractory CHF is defined as symptoms of CHF at rest or repeated exacerbations of CHF despite “optimal” triple-drug therapy. Most patients with refractory CHF require hemodynamic monitoring and treatment in the intensive care unit. If easily reversible causes of refractory CHF cannot be identified, then more aggressive medical and surgical interventions are necessary. The primary goal of intervention is to improve hemodynamics to palliate CHF symptoms and signs (i.e., dyspnea, fatigue, edema). Secondary goals include improved vital organ and tissue perfusion, discharge from the intensive care unit, and, in appropriate patients, bridge to cardiac transplantation. Medical interventions include inotropic resuscitation (e.g., adrenergic agents, phosphodiesterase inhibitors, allied nonglycoside inodilators), load resuscitation (e.g., afterload and preload reduction with nitroprusside or nitroglycerin; preload reduction with diuretics and diuretic facilitators, such as dopaminergic agents or ultrafiltration), and electrical resuscitation (e.g., prevention of sudden death, correction of new or rapid atrial fibrillation, or dual chamber pacing in the setting of relative prolongation of the PR interval and diastolic mitral/tricuspid regurgitation). Surgical interventions are temporizing (e.g., intra-aortic balloon pump and other mechanical assist devices) or definitive (e.g., coronary artery revascularization, valvular surgery, and cardiac transplantation). Although these interventions may improve immediate survival in the short term, only coronary artery revascularization and cardiac transplantation have been shown to improve long-term survival.

Refractory congestive heart failure: overview and application of extracorporeal ultrafiltration

Congestive heart failure (CHF) from ischemic cardiomyopathy has emerged as an epidemic health problem. The pathogenesis of CHF is characterized by heightened activity of many neuroendocrine factors, including norepinephrine, angiotensin II, and arginine vasopressin, which lead to heightened systemic vascular resistance and further impedance of left ventricular ejection. Once CHF reaches New York Heart Association (NYHA) class III or IV with heightened activity of the many neurohumoral factors, it tends to be refractory to conventional therapy of vasodilators, inotropic agents, and diuretics. Treatment of refractory CHF appears to require a break in the neurohumoral hemodynamic vicious cycle, and ultrafiltration appears able to produce this interruption. Ultrafiltration has been shown to be successful in patients with NYHA class III to VI CHF and urine output less than 1,000 mL/d. It relieves pulmonary edema, reduces ascites and peripheral edema, and enhances the response to subsequent diuretic therapy. In patients with refractory CHF, the ability to provide adequate volume removal, thus improving overall volume status, normalizing filling pressures, and reducing clinical symptoms, offers an improvement in overall quality of life. Early results have shown that ongoing therapy actually may be associated with decreased hospital readmissions or, at the very least, shortened intensive care unit length of stay.

Apparent paradox of neurohumoral axis inhibition after body fluid volume depletion in patients with chronic congestive heart failure and water retention

BACKGROUND

Hypovolaemia stimulates the sympathoadrenal and renin systems and water retention. It has been proposed that in congestive heart failure reduction of cardiac output and any associated decrease in blood pressure cause underfilling of the arterial compartment, which promotes and perpetuates neurohumoral activation and the retention of fluid. This study examined whether an intravascular volume deficit accounts for patterns that largely exceed the limits of a homoeostatic response, which are sometimes seen in advanced congestive heart failure.

METHODS AND RESULTS

In 22 patients with congestive heart failure and water retention the body fluid mass was reduced by ultrafiltration and the neurohumoral reaction was monitored. A Diafilter, which was part of an external venous circuit was regulated to produce 500 ml/hour of ultrafiltrate (mean (SD) 3122 (1199) ml) until right atrial pressure was reduced to 50% of baseline. Haemodynamic variables, plasma renin activity, noradrenaline, and aldosterone were measured before and within 48 hours of ultrafiltration. After ultrafiltration, which produced a 20% reduction of plasma volume and a moderate decrease in cardiac output and blood pressure (consistent with a diminished degree of filling of the arterial compartment), there was an obvious decrease in noradrenaline, plasma renin activity, and aldosterone. In the next 48 hours plasma volume, cardiac output, and blood pressure recovered; the neurohumoral axis was depressed; and there was a striking enhancement of water and sodium excretion with resolution of the peripheral oedema and organ congestion. The neurohumoral changes and haemodynamic changes were not related. There were significant correlations between the neurohumoral changes and increase in urinary output and sodium excretion.

CONCLUSIONS

In advanced congestive heart failure arterial underfilling was not the main mechanism for activating the neurohumoral axis and retaining fluid. Because a decrease in circulating hormones was associated with reabsorption of extravascular fluid it is likely that hypoperfusion and/or congestion of organs, such as the kidney and lung, reduce the clearance of circulating noradrenaline and help to keep plasma concentrations of renin and aldosterone raised. A positive feedback loop between fluid retention and plasma hormone concentrations may be responsible for progression of congestive heart failure.

Sustained improvement in functional capacity after removal of body fluid with isolated ultrafiltration in chronic cardiac insufficiency: failure of furosemide to provide the same result

OBJECTIVES

This study was designed to investigate whether a subclinical accumulation of fluid in the lung interstitium associated with moderate congestive heart failure interferes with the patient's functional capacity, and whether furosemide treatment can promote reabsorption of the excessive fluid.

BACKGROUND

In patients with moderate congestive heart failure, pulmonary overhydration may be detected by chest roentgenography even if therapy is optimized to keep the urinary output normal and to prevent weight gain and dependent edema formation. Removal of the overhydration may help define its significance.

METHODS

Patients, whose regimens of digoxin, oral furosemide, and angiotensin-converting enzyme (ACE) inhibitor therapy were kept constant, were randomly allocated to receive ultrafiltration (8 cases) or an intravenous bolus of supplemental furosemide (mean dose: 248 mg; 8 cases). The amount of body fluid removed with each method approximated 1600 mL. Functional performance was assessed with cardiopulmonary exercise tests.

RESULTS

Soon after fluid withdrawal by either method, the filling pressures of the two ventricles and body weight were reduced and plasma renin activity, norepinephrine, and aldosterone were augmented. After furosemide administration, hormone levels remained elevated for the next 4 days, and during this period, patients had positive water metabolism, recovery of the elevated ventricular filling pressures, and re-occurrence of lung congestion with no improvement in functional capacity. After ultrafiltration, levels of renin, norepinephrine, and aldosterone fell to below control values within the first 48 hours and water metabolism was equilibrated at a new set point (less fluid intake and diuresis without weight gain). The favorable circulatory and ventilatory adjustments consequent to the reabsorption of lung water improved the functional capacity of these patients. That may also have restored the lung's ability to clear norepinephrine, thus restraining its facilitation of renin release. The improvement continued 3 months after the procedure.

CONCLUSIONS

In patients with congestive heart failure the set point of fluid balance is altered in spite of oral furosemide therapy; supplemental intravenous furosemide does not shift the set point, at least not when combined with ACE inhibition. Excessive, although asymptomatic, lung water limits the functional capacity of the patient.

Sustained cardiac diastolic changes elicited by ultrafiltration in patients with moderate congestive heart failure: pathophysiological correlates

OBJECTIVE

To investigate the pathophysiological (cardiac function and physical performance) significance of clinically silent interstitial lung water accumulation in patients with moderate heart failure; to use isolated ultrafiltration as a means of extravascular fluid reabsorption.

DESIGN

Echocardiographic, Doppler, chest x-ray evaluations, and cardiopulmonary tests at baseline, soon after ultrafiltration (veno venous extracorporeal circuit), and four days, one month, and three months later.

SETTING

University institute of cardiology.

SUBJECTS

24 patients with heart failure due to idiopathic dilated cardiomyopathy or ischaemic myocardial disease with sinus rhythm and ejection fraction less than 35%. Twelve were randomised to ultrafiltration and 12 were taken as controls.

MAIN OUTCOME MEASURES

Left ventricular systolic function (from ultrasonography); Doppler evaluation of mitral, tricuspid, and aortic flow and echo-Doppler determination of cardiac output; radiological score of extravascular lung water; right and left ventricular filling pressures; oxygen consumption at peak exercise and exercise tolerance time in cardiopulmonary tests.

RESULTS

Soon after ultrafiltration (1976 (760) ml of fluid removed) the following was observed: a reduction in radiological score of extravascular lung water (from 15(1) to 9(1)) and of right (from 7.1 (2.3) to 2.3 (1.7) mm Hg) and left (from 17.6 (8.8) to 9.5 (6.4) mm Hg) ventricular filling pressures; an increase in oxygen consumption at peak exercise (from 15.8 (3.3) to 17.6 (2) ml/min/kg) and of tolerance time (from 444 (138) to 508 (134) s); a slight decrease in atrial and ventricular dimensions; no changes in the systolic function of the left ventricle; a reduction of the early to late filling ratio in both ventricles (mitral valve from 2 (2) to 1.1 (1.1)); (tricuspid valve from 1.3 (1.3) to 0.69 (0.18)) and an increase in the deceleration time of mitral and tricuspid flow, reflecting a redistribution of filling to late diastole. Variations in the ventricular filling pattern, lung water content, and functional performance persisted for three months in all cases. None of these changes was detected in the control group.

CONCLUSIONS

Reduction of interstitial lung water was probably the mechanism whereby ultrafiltration modified the pattern of filling of the two ventricles and improved functional performance.

Isolated ultrafiltration in moderate congestive heart failure

OBJECTIVES

The aim of this study was to evaluate whether ultrafiltration is beneficial in patients with moderate congestive heart failure.

BACKGROUND

Ultrafiltration is beneficial in patients with severe congestive heart failure.

METHODS

We studied 36 patients in New York Heart Association functional classes II and III in stable clinical condition. Eighteen patients (group A) were randomly selected and underwent a single session of ultrafiltration (venovenous bypass, mean [+/- SEM] ultrafiltrate 1,880 +/- 174 ml, approximately 600 ml/h) and 18 (group B) served as control subjects.

RESULTS

Two patients in group A and three in group B did not complete the 6-month follow-up study. In group A, soon after ultrafiltration there were significant reductions in right atrial pressure (from 8 +/- 1 to 3.4 +/- 0.7 mm Hg, pulmonary wedge pressure (from 18 +/- 2.5 to 10 +/- 1.9 mm Hg) and cardiac index (from 2.8 +/- 0.2 to 2.3 +/- 0.2 liters/min). During the follow-up period, lung function improved, extravascular lung water (X-ray score) decreased and peak oxygen consumption (ml/min per kg) increased significantly from 15.5 +/- 1 (day -1) to 17.6 +/- 0.9 (day 4), to 17.8 +/- 0.9 (day 30), to 18.9 +/- 1 (day 90) and to 19.1 +/- 1 (day 180). Oxygen consumption at anaerobic threshold (ml/min per kg) also increased significantly from 11.6 +/- 0.8 (day -1) to 13 +/- 0.7 (day 4), to 13.7 +/- 0.5 (day 30), to 15.5 +/- 0.8 (day 90) and to 15.2 +/- 0.8 (day 180). These changes were associated with increased ventilation, tidal volume and dead space/tidal volume ratio at peak exercise. The improvement in exercise performance was associated with a decrease in norepinephrine at rest, a downward shift of norepinephrine kinetics at submaximal exercise and an increase in norepinephrine during orthostatic tilt. None of these changes were recorded in group B.

CONCLUSIONS

In patients with moderate congestive heart failure, ultrafiltration reduces the severity of the syndrome.

Interrelation of humoral factors, hemodynamics, and fluid and salt metabolism in congestive heart failure: effects of extracorporeal ultrafiltration

PURPOSE

We investigated the mechanisms involved in the regulation of salt and water metabolism in patients with congestive heart failure (CHF). Extracorporeal ultrafiltration was utilized as a nonpharmacologic method for withdrawal of body fluid.

PATIENTS, METHODS, AND RESULTS

In 32 consecutive patients with CHF (New York Heart Association functional class II to IV) and different degrees of water retention, 24-hour diuresis and natriuresis were inversely best correlated with the combination of circulating renin, aldosterone, norepinephrine, and renal perfusion pressure (RPP, mean aortic pressure minus mean right atrial pressure). Fluid withdrawal (600 to 5,000 mL) at a rate of 500 mL/h, until right atrial pressure decreased to 50% of baseline, caused variable humoral, circulatory, and diuretic effects that were mainly related to the extent of fluid retention. In fact, in 10 patients (Group 1) with overhydration refractory to drug therapy and with urinary output less than 1,000 mL/24 h (mean, 370 mL), soon after the procedure, plasma renin (-39%), aldosterone (-50%), and norepinephrine (-47%) were reduced and RPP was increased (+16%), and in the subsequent 24 hours, diuresis was increased by 493%; in 9 patients (Group 2) whose baseline urinary output exceeded 1,000 mL/24 h (mean, 1,785 mL), renin increased by 40%, norepinephrine, aldosterone, and RPP each decreased by 12%, and diuresis remained unchanged; in 13 patients (Group 3) with a daily urinary excretion as in Group 2 and without overhydration, RPP decreased (-7%), renin (+196%), aldosterone (+170%), and norepinephrine (+52%) increased, and diuresis decreased by 45%. There was an overall correlation (p < 0.0001) between the combination of changes in these circulatory and hormonal variables and changes in diuresis and natriuresis with ultrafiltration.

CONCLUSIONS

It appears that in CHF, (1) retention of sodium and water results from an interaction of hormonal and hemodynamic (primarily RPP) alterations that may exert a reciprocal positive feedback; (2) depending on the presence and severity of fluid retention, the response to withdrawal of body fluid may vary from neurohumoral activation and restriction of diuresis to neurohumoral depression and extreme potentiation of salt and water excretion; (3) refractory CHF requires the interruption of the humoral-hemodynamic vicious circle, and ultrafiltration is able to accomplish that.