Intravascular Volume Profiles in Patients With Class I and II Systolic Heart Failure: Heterogeneity and Volume Overload Are Common Even in Mild Heart Failure

Congestion/decongestion in heart failure: what does it mean, how do we assess it, and what are we missing?-is there utility in measuring volume?

Clinical congestion remains a major cause of hospitalization and re-hospitalizations in patients with chronic heart failure (HF). Despite the high prevalence of this issue and clinical concern in HF practice, there is limited understanding of the complex pathophysiology relating to the "congestion" of congestive HF. There is no unifying definition or clear consensus on what is meant or implied by the term "congestion." Further, the discordance in study findings relating congestion to physical signs and symptoms of HF, cardiac hemodynamics, or metrics of weight change or fluid loss with diuretic therapy has not added clarity. In this review, these factors will be discussed to add perspective to this issue and consider the factors driving "congestion." There remains a need to better understand the roles of fluid retention promoting intravascular and interstitial compartment expansions, blood volume redistribution from venous reservoirs, altered venous structure and capacity, elevated cardiac filling pressure hemodynamics, and heterogeneous intravascular volume profiles (plasma volume and red blood cell mass) with a goal to help demystify "congestion" in HF. Further, this includes highlighting the importance of recognizing that congestion is not the result of a single pathway but a complex of responses some of which produce symptoms while others do not; yet, we confine these varied responses to the single and somewhat vague term "congestion."

Patient Sex Impacts Volume Phenotypes and Hemodynamics in Chronic Heart Failure: A Multicenter Analysis

BACKGROUND

Quantitative methods have shown clinically significant heterogeneity in blood volume (BV) profiles in patients with chronic heart failure (HF). How patients' sex might impact this volume heterogeneity and its relationship to cardiac hemodynamics remains to be defined.

METHODS

Retrospective analysis of clinical and quantitative BV, plasma volume (PV) and red blood cell (RBC) mass data was undertaken across 3 medical centers. BV was quantitated using nuclear medicine I-131-labeled plasma albumin indicator-dilution methodology with cardiac hemodynamics obtained within 24 hours.

RESULTS

In an analysis of 149 males and 106 females, absolute BV was greater, on average, in males (6.9 ± 1.7 vs 5.0 ± 1.2 liters; P < 0.001); however, a wide range in BVs was demonstrated in both sexes (2.9-14.5 liters). Male sex was associated with higher prevalence of large (+ 25% of normal) BV and PV expansions (36% vs 15% and 51% vs 21%, respectively; both P < 0.001). In contrast, female sex was associated with higher prevalence of normal total BV (44% vs 27%; P = 0.005), PV (54% vs 27%; P < 0.001), hypovolemia (23% vs 11%; P = 0.005), and true anemia (42% vs 26%; P < 0.001). Cardiac hemodynamics differed by sex, but only modest associations were demonstrated between volume profiles and cardiac filling pressures.

CONCLUSIONS

Findings support unique intravascular volume profiles reflecting sex-specific differences in the prevalence and distributions of total BV, PV and RBC mass profiles in patients with chronic HF. This underscores the importance of recognizing patients' sex as a significant factor influencing volume homeostasis, which needs to be taken into account to individualize volume-management strategies effectively.

Comparison of Blood Volume Profiles in Heart Failure With Preserved and Reduced Ejection Fractions: Sex Makes a Difference

BACKGROUND

Blood volume (BV) profiles vary markedly in patients with heart failure (HF), but how HF phenotypes and patient sex impact volume profiles remain to be explored. The aim of the study was to differentiate BV, plasma volume, and red blood cell mass profiles by phenotypes of preserved and reduced left ventricular ejection fractions and assess the impact of patient sex on profile heterogeneity.

METHODS

Retrospective analysis of clinical and BV data was undertaken in patients with chronic New York Heart Association II-III heart failure. BV was quantitated using the nuclear medicine indicator-dilution methodology.

RESULTS

A total of 530 BV analyses (360 HF with reduced ejection fraction and 170 HF with preserved ejection fraction) were identified in 395 unique patients. Absolute BV was greater in HF with reduced ejection fraction (6.7±1.8 versus 5.9±1.6 liters: P<0.001); however, large variability in frequency distribution of volume profiles was observed in both phenotypes (-22% deficit to +109% excess relative to normal volumes). HF with reduced ejection fraction was characterized by a higher prevalence of BV expansion ≥+25% of normal (39% versus 26%; P=0.003), and HF with preserved ejection fraction was characterized a by more frequent normal BV (42% versus 24%; P<0.001). Male sex in both phenotypes was associated with a larger absolute BV (7.0±1.6 versus 5.1±1.3 liters; P<0.001) and higher frequency of large BV and plasma volume expansions above normal (both P<0.001), while females in both phenotypes demonstrated a higher prevalence of normal BV and plasma volume (both P<0.001).

CONCLUSIONS

Findings support significant differences in BV, plasma volume, and red blood cell mass profile distributions between heart failure phenotypes, driven in large part by sex-specific factors. This underscores the importance of identifying and distinguishing individual patient volume profiles to help guide volume management strategies.

Clinical importance of distinguishing true anemia from dilutional pseudo-anemia: Consequences of a 3-year follow-up volume assessment in a heart failure patient

In chronic heart failure, dilutional anemia and hypervolemia may occur due to plasma volume expansion, the latter sometimes exacerbated by an increase in red cell volume. Diagnosis and a therapeutic strategy require determination of vascular volumes.

Clinically unrecognized plasma volume expansion predicts long-term all-cause-mortality in chronic heart failure

INTRODUCTION

Chronic heart failure (CHF) is associated with elevated total blood volume (BV) and distinct phenotypes of total red cell volume (RCV) and plasma volume (PV) elevations. Especially PV expansion during clinical decompensation is linked with adverse clinical outcomes. The role of PV expansion in compensated CHF patients is less clear. Aim of the present study is to investigate the impact of BV parameters on long-term mortality in CHF patients investigated at a compensated state.

METHODS AND RESULTS

BV, PV and RCV were determined in 44 (9 female) compensated CHF patients using an abbreviated carbon monoxide method, who were followed up for 6.0 years, (range: 3.7-6.5 years) for all-cause mortality. In univariate analysis PV expansion but not BV and RCV predicted all-cause mortality (p = .021). A cutoff of 1800 ml PV/m² body-surface area allows stratification for all-cause mortality (p = .044). PV expansion but not RCV reduction explains the significantly lower hematocrit values of nonsurvivors.

DISCUSSION

In this pilot study, PV expansion, which was unnoticed from a clinician's perspective, but is indicated by significantly lower hematocrit, appears to be a relevant predictor of long-term all-cause mortality. Whether PV expansion constitutes an adverse CHF phenotype and can be targeted by diuretic therapy is currently unclear.

Fluid Volume Homeostasis in Heart Failure: A Tale of 2 Circulations

Fluid volume homeostasis in health and heart failure (HF) requires a complex interaction of 2 systems, the intravascular and interstitial-lymphatic circulations. With the development of HF both the intravascular and interstitial compartments undergo variable degrees of volume remodeling which can include significant expansion. This reflects the impact of multiple pathophysiologic mechanisms on both fluid compartments which initially play a compensatory role to stabilize intravascular circulatory integrity but with progression in HF can evolve to produce the various manifestations of volume overload and clinical HF congestion. The intent of this review is to help enhance recognition of the pathophysiologic and clinical importance of the interlinked roles of these 2 circulatory systems in volume regulation and chronic HF. It would also be hoped that a better understanding of the interacting functions of the intravascular and interstitial-lymphatic fluid compartments can potentially aid development of novel management strategies particularly addressing the generally undertargeted interstitial-lymphatic system and help bring such approaches forward through a more integrated view of these 2 circulatory systems.

Blood volume expansion, normovolemia, and clinical outcomes in chronic human heart failure: more is better

Expansion in blood volume (BV) is a well-recognized response to arterial underfilling secondary to impaired cardiac output in heart failure (HF). However, the effectiveness of this response in terms of outcomes remains inadequately understood. Prospective analysis was undertaken in 110 patients with HF hospitalized and treated for fluid overload. BVs were measured in a compensated state at the hospital discharge using the indicator-dilution methodology. Data were analyzed for composite 1-year HF-related mortality/first rehospitalization. Despite uniform standard of care, marked heterogeneity in BVs was identified across the cohort. The cohort was stratified by BV expansion greater than or equal to +25% above normal (51% of cohort), mild-moderate expansion (22%), and normal BV (27%). Kaplan-Meier (K-M) survival estimates and regression analyses revealed BV expansion (greater than or equal to +25%) to be associated with better event-free survival relative to normal BV (P = 0.038). Increased red blood cell mass (RBCm; RBC polycythemia) was identified in 43% of the overall cohort and 70% in BV expansion greater than or equal to +25%. K-M analysis demonstrated polycythemia to be associated with better outcomes compared with normal RBCm (P < 0.002). Persistent BV expansion to include RBC polycythemia is common and, importantly, associated with better clinical outcomes compared with normal total BV or normal RBCm in patients with chronic HF. However, compensatory BV expansion is not a uniform physiological response to the insult of HF with marked variability in BV profiles despite uniform standard of care diuretic therapy. Therefore, recognizing the variability in volume regulation pathophysiology has implications not only for impact on clinical outcomes and risk stratification but also potential for informing individualized volume management strategies.NEW & NOTEWORTHY The novel findings of this study demonstrate that intravascular volume profiles among the patients with chronic heart failure (HF) vary substantially even with similar clinical compensation. Importantly, a profile of blood volume (BV) expansion (compared with a normal BV) is associated with lower HF mortality/morbidity. Furthermore, RBC polycythemia is common and independently associated with improved outcomes. These observations support BV expansion with RBC polycythemia as a compensatory mechanism in chronic HF.

Blood volume and hemoglobin mass in long-term heart transplant recipients with and without Anemia

BACKGROUND

In systolic chronic heart failure, a heterogeneous blood volume (BV) regulation can be found with plasma volume expansion in many cases, possibly leading to pseudoanemia. Little is known about the volume status after heart transplantation (HTX). So far, anemia of HTX recipients was solely investigated using hemoglobin-concentration that may be misleading in a clinical context. The objective of the study was whether a difference in plasma volume and red cell volume can be observed in clinically stable heart transplant recipients compared to matched control subjects. Secondary, the aim was to describe anemia in the long-term after HTX based on quantitative data.

METHODS

Blood volume and its constituents red cell volume and plasma volume were quantified using an abbreviated carbon monoxide rebreathing method (aCORM) with focus on its primary measure total hemoglobin mass (Hbmass) and coincidental anemia in 36 (7 women) heart transplant recipients. For comparison, a matched control group of 46 (5 women) healthy subjects was selected.

RESULTS

Neither Hbmass nor blood volumes were significantly different in HTX patients compared to matched healthy control group subjects. The prevalence of anemia 6.3 ± 4.3 years after transplantation was 19%. Hbmass and red cell volume were significantly lower in anemic HTX patients compared to non-anemic patients while plasma volume was not expanded. Various immunosuppressant regimens did not have an effect on Hbmass, plasma volume or red cell volume.

CONCLUSIONS

There was no difference in blood volumes and Hbmass between HTX patients and control subjects. The pathophysiologic blood volume regulation in chronic heart failure does not seem to be longer active in long-term HTX recipients. However, in the long-term after HTX, anemia occurs in a considerable number of patients as true anemia without a clear association with immunosuppression.

TRIAL REGISTRATION

German registry for clinical studies, DRKS00006078. Registered 09 May 2014, https://www.drks.de/drks_web/navigate.do?navigationId=trial . HTML&TRIAL_ID=DRKS00006078.

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Time course of red cell volume and plasma volume over six months in compensated chronic heart failure

Background

In patients with chronic heart failure (CHF), volume overload is usually described as an expansion of plasma volume (PV). Additional red cell volume (RCV) expansion also occurs in a relevant fraction of compensated CHF patients. So far, little is known about the stability of these vascular volumes and possible volume excess in compensated CHF patients over time.

Methods and results

This study aims at quantification of blood volume and its components, RCV and PV (raw values and adjusted for sex and anthropometric characteristics, expressed as per cent of the expected normal value), using an abbreviated carbon monoxide (CO) rebreathing method (aCORM) in 14 patients (two women) with systolic CHF at baseline and at a follow‐up visit after approximately 6 months. While a vast heterogeneity was observed concerning RCV (82% to 134% of normalized alues) and PV (72% to 131% of normalized values), the vascular volumes showed a mean change of 1.2% and −1.3% after a mean follow‐up of 183 days.

Conclusions

The vascular volumes including individual volume excess appear to be stable in compensated CHF patients. The reason for this individual volume response concerning both RCV and PV in CHF remains unclear and deserves further clarification.

Impact of calculated plasma volume status on all-cause and cardiovascular mortality: 4-year nationwide community-based prospective cohort study

Background

Plasma volume status (PVS), a marker of plasma volume expansion and contraction, is gaining attention in the field of cardiovascular disease because of its role in the prevention and of the management of heart failure. However, it remains undetermined whether an abnormal PVS is a risk for all-cause and cardiovascular mortality in the general population.

Methods and results

We used a nationwide database of 230,882 subjects (age 40–75 years) who participated in the annual “Specific Health Check and Guidance in Japan” check-up between 2008 and 2011. There were 586 cardiovascular deaths, 2,552 non-cardiovascular deaths, and 3,138 all-cause deaths during the follow-up period of four years. Abnormally high and low PVS were identified from the results of 80% of all subjects (high and low PVS ≥ 7 and < -13.3, respectively). Multivariate Cox proportional hazard regression analysis demonstrated that high PVS was an independent risk factor for all-cause, cardiovascular and non-cardiovascular deaths. Although low PVS was a positive risk factor for cardiovascular deaths as well, it was a negative risk factor for non-cardiovascular deaths. The addition of PVS to cardiovascular risk factors significantly improved the C-statistic, net reclassification, and integrated discrimination indexes.

Conclusions

This is the first prospective report to reveal the impact of PVS on all-cause and cardiovascular mortality. PVS could be an additional risk factor for all-cause and cardiovascular mortality in the general population.

Increased Red Cell Volume Is a Relevant Contributing Factor to an Expanded Blood Volume in Compensated Systolic Chronic Heart Failure

BACKGROUND

In patients with chronic heart failure (CHF), volume overload is usually described as an expansion of plasma volume. Additional red cell volume (RCV) expansion is less commonly recognized. So far, little is known about quantitative differences in blood volume status and its different components in patients with stable CHF compared to healthy controls.

METHODS

This study aimed to quantify blood volume and its constituents, RCV and plasma volume, by using an abbreviated carbon monoxide rebreathing method with particular focus on its primary measure total hemoglobin mass in 47 patients (10 women) with systolic CHF and a left ventricular ejection fraction of 29.0 ± 9.4%. These were compared to an age-matched control group of 84 healthy subjects (44 women) using the same method.

RESULTS

In both absolute and body-surface-area-corrected analysis, hemoglobin mass (446 ± 81 vs 353 ± 64 g/m²) as well as RCV (1293 ± 231 vs 1033 ± 176 mL/m²) were significantly increased in CHF. In addition, significant plasma volume expansion was observed in CHF (2069 ± 400 vs 1750 ± 231 mL/m²) and, in conjunction with RCV, constituted a significantly increased blood volume (3361 ± 574 vs 2783 ± 369 mL/m²). In 66% of patients with compensated CHF, RCV was excessive compared to 14% in the control group.

CONCLUSIONS

An increased RCV is a relevant contributing factor to hypervolemia in stable CHF. This is associated with an increased oxygen-carrying capacity, so it may be regarded as a possible compensatory mechanism for a reduced ejection fraction.

Impact of Obesity on Volume Status in Patients With Ambulatory Chronic Heart Failure

BACKGROUND

Fluid overload is common in heart failure (HF) and obesity; however, the relationship between the extent of intravascular volume expansion and indices such as body mass index (BMI) in obese and non-obese patients with HF has not been defined to address the issue of a HF obesity phenotype.

METHODS

Total blood volume (TBV) was measured clinically using a radiolabeled albumin indicator-dilution technique in patients with predominately class III ambulatory chronic HF (N=66). Obesity was defined by BMI ≥30 kg/m².

RESULTS

Markedly increased intravascular volume expansion (defined by TBV expansion >+25% above normal) was highly prevalent in the obese (53%) compared to non-obese patients with HF (29%, P = .04) driven by plasma volume expansion. TBV was correlated with excess body weight and BMI (both P < .01). Also, cardiac index was higher, systemic vascular resistance lower, and left ventricular filling pressures comparable in obese compared with non-obese patients.

CONCLUSIONS

Quantitative assessment of intravascular volume demonstrates for the first time that severe (not mild or moderate) volume expansion is highly common in obese patients with ambulatory chronic HF. This supports an evolving concept of an obesity-specific HF phenotype. Further study is needed to understand the mechanisms controlling volume regulation and the potential compensatory or detrimental impact on outcomes in obesity and HF.

Calculated Estimates of Plasma Volume in Patients With Chronic Heart Failure-Comparison With Measured Volumes

BACKGROUND

Calculated estimates of plasma volume (PV) have been developed with the use of hemoglobin/hematocrit-body weight-based methods. The accuracy of such formula-derived values has not been thoroughly evaluated. The objective of this analysis was to compare the calculated estimate and a quantitative measure of PV in patients with chronic heart failure (HF).

METHODS AND RESULTS

PV was measured with the use of a standardized computer-based indicator-dilution-labeled albumin technique in 110 patients with clinically stable chronic HF and correlated with paired Kaplan-Hakim (K-H) and Strauss formula estimates of PV. The K-H formula underestimated (3.4 ± 0.7 L) and the Strauss formula overestimated (5.3 ± 1.5 L) PV relative to the measured volume (4.3 ± 1.1 L). Calculated PV was only moderately correlated with measured PV by the K-H formula (r = 0.64; P < .001) and weakly by the Strauss formula (r = 0.285; P = .003). Strauss formula estimates of change (%) in PV were also poorly correlated with paired measured changes in PV (r = 0.162; P = .999; n = 40).

CONCLUSIONS

Calculated estimates of PV demonstrate limited association with measured volumes. These findings indicate that although formula-based estimates of PV have been shown to have prognostic value, they are limited in their reliability for volume management in patients with chronic HF.