Greater Splanchnic Nerve Stimulation in Heart Failure With Preserved Ejection Fraction

The sympathetic nervous system in heart failure with preserved ejection fraction

The sympathetic nervous system (SNS) is a major mediator of cardiovascular physiology during exercise in healthy people. However, its role in heart failure with preserved ejection fraction (HFpEF), where exercise intolerance is a cardinal symptom, has remained relatively unexplored. The present review summarizes and critically explores the currently limited data on SNS changes in HFpEF patients with a particular emphasis on caveats of the data and the implications for its subsequent interpretation. While direct measurements of SNS activity in HFpEF patients is scarce, modest increases in resting levels of muscle sympathetic nerve activity are apparent, although this may be due to the co-morbidities associated with the syndrome rather than HFpEF per se. In addition, despite some evidence for dysfunctional sympathetic signaling in the heart, there is no clear evidence for elevated cardiac sympathetic nerve activity. The lack of a compelling prognostic benefit with use of β-blockers in HFpEF patients also suggests a lack of sympathetic hyperactivity to the heart. Similarly, while renal and splanchnic denervation studies have been performed in HFpEF patients, there is no concrete evidence that the sympathetic nerves innervating these organs exhibit heightened activity. Taken together, the totality of data suggests limited evidence for elevated sympathetic nerve activity in HFpEF and that any SNS perturbations that do occur are not universal to all HFpEF patients. Finally, how the SNS responds during exertion in HFpEF patients remains unknown and requires urgent investigation.

Endovascular Ablation of the Greater Splanchnic Nerve in Heart Failure With Preserved Ejection Fraction: The REBALANCE-HF Randomized Clinical Trial

Importance

Greater splanchnic nerve ablation may improve hemodynamics in patients with heart failure and preserved ejection fraction (HFpEF).

Objective

To explore the feasibility and safety of endovascular right-sided splanchnic nerve ablation for volume management (SAVM).

Design, Setting, and Participants

This was a phase 2, double-blind, 1:1, sham-controlled, multicenter, randomized clinical trial conducted at 14 centers in the US and 1 center in the Republic of Georgia. Patients with HFpEF, left ventricular ejection fraction of 40% or greater, and invasively measured peak exercise pulmonary capillary wedge pressure (PCWP) of 25 mm Hg or greater were included. Study data were analyzed from May 2023 to June 2024.

Intervention

SAVM vs sham control procedure.

Main Outcomes and Measures

The primary efficacy end point was a reduction in legs-up and exercise PCWP at 1 month. The primary safety end point was serious device- or procedure-related adverse events at 1 month. Secondary efficacy end points included HF hospitalizations, changes in exercise function and health status through 12 months, and baseline to 1-month change in resting, legs-up, and 20-W exercise PCWP.

Results

A total of 90 patients (median [range] age, 71 [47-90] years; 58 female [64.4%]) were randomized at 15 centers (44 SAVM vs 46 sham). There were no differences in adverse events between groups. The primary efficacy end point did not differ between SAVM or sham (mean between-group difference in PCWP, -0.03 mm Hg; 95% CI, -2.5 to 2.5 mm Hg; P = .95). There were also no differences in the secondary efficacy end points. There was no difference in the primary safety end point between the treatment (6.8% [3 of 44]) and sham (2.2% [1 of 46]) groups (difference, 4.6%; 95% CI, -6.1% to 15.4%; P = .36). There was no difference in the incidence of orthostatic hypotension between the treatment (11.4% [5 of 44]) and sham (6.5% [3 of 46]) groups (difference, 4.9%; 95% CI, -9.2% to 18.8%; P = .48).

Conclusions and Relevance

Results show that SAVM was safe and technically feasible, but it did not reduce exercise PCWP at 1 month or improve clinical outcomes at 12 months in a broad population of patients with HFpEF.

Trial Registration

ClinicalTrials.gov Identifier: NCT04592445.

Role of splanchnic circulation in the pathogenesis of heart failure: State-of-the-art review

A hallmark of heart failure (HF), whether it presents itself during rest or periods of physical exertion, is the excessive elevation of intracardiac filling pressures at rest or with exercise. Many mechanisms contribute to the elevated intracardiac filling pressures, and notably, the concept of volume redistribution has gained attention as a cause of the elevated intracardiac filling pressures in patients with HF, particularly HF with preserved ejection fraction, who often present without symptoms at rest, with shortness of breath and fatigue appearing only during exertion. This phenomenon suggests cardiopulmonary system non-compliance and inappropriate volume distribution between the stressed and unstressed blood volume components. A substantial proportion of the intravascular blood volume is in the splanchnic vascular compartment in the abdomen. Preclinical and clinical investigations support the critical role of the sympathetic nervous system in modulating the capacitance and compliance of the splanchnic vascular bed via modulation of the greater splanchnic nerve (GSN). The GSN activation by stressors such as exercise causes excessive splanchnic vasoconstriction, which may contribute to the decompensation of chronic HF via volume redistribution from the splanchnic vascular bed to the central compartment. Accordingly, for example, GSN ablation for volume management has been proposed as a potential therapeutic intervention to increase unstressed blood volume. Here we provide a comprehensive review of the role of splanchnic circulation in the pathogenesis of HF and potential novel treatment options for redistributing blood volume to improve symptoms and prognosis in patients with HF.

Preload Reduction Therapies in Heart Failure

Preload reserve represents an important concept in the normal physiologic responses of the body to meet the changing metabolic demands. The recruitment of preload in healthy patients leads to an increase in effective circulating blood volume with a concomitant increase in cardiac output. However, in the setting of heart failure (HF), preload augmentation may precipitate HF decompensation. In this review, we focus on the role of splanchnic nerve modulation and pharmacological therapeutic interventions to prevent HF decompensation through preload reduction. Furthermore, we explore the emerging device-based approaches for cardiac preload reduction while reviewing the ongoing clinical trials.

Splanchnic Nerve Modulation Effects on Surrogate Measures of Venous Capacitance

Background Splanchnic nerve modulation (SNM) is an emerging procedure to reduce cardiac filling pressures in heart failure. Although the main contributor to reduction in cardiac preload is thought to be increased venous capacitance in the splanchnic circulation, supporting evidence is limited. We examined changes in venous capacitance surrogates pre- and post-SNM. Methods and Results This is a prespecified analysis of a prospective, open-label, single-arm interventional study evaluating the effects of percutaneous SNM with ropivacaine in chronic heart failure with elevated filling pressures at rest and with exercise. Patients underwent cardiopulmonary exercise testing with invasive hemodynamic assessment pre- and post-SNM. Blood pressure changes with modified Valsalva maneuver and hemoconcentration, pre- and post-SNM were compared using a repeated measures model. Inferior vena cava diameter and collapsibility (>50% decrease in size with inspiration), and presence of bendopnea pre- and post-SNM were also compared. Fifteen patients undergoing SNM (age 58 years, 47% women, 93% with left ventricular ejection fraction ≤35%) were included. After SNM, changes in systolic blood pressure during Valsalva (peak-to-trough) were greater (41 versus 48 mm Hg, P=0.025). Exercise-induced hemoconcentration was unchanged (0.63 versus 0.43 g/dL, P=0.115). Inferior vena cava diameter was reduced (1.59 versus 1.30 cm, P=0.034) with higher collapsibility (33% versus 73%, P=0.014). Bendopnea was less (47% versus 13%, P=0.025). Conclusions SNM resulted in increased venous capacitance, associated decreased cardiac preload, and decreased bendopnea. Minimally invasive measures of venous capacitance could serve as markers of successful SNM. Long-term effects of SNM on venous capacitance warrant further investigation for heart failure management. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03453151.

Endovascular Ablation of the Right Greater Splanchnic Nerve in Heart Failure with Preserved Ejection Fraction: Early Results of the REBALANCE-HF Trial Roll-in Cohort

Aims

In heart failure (HF) with preserved ejection fraction (HFpEF), excessive redistribution of blood volume into the central circulation leads to elevations of intracardiac pressures with exercise limitations. Splanchnic ablation for volume management (SAVM) has been proposed as a therapeutic intervention. Here we present preliminary safety and efficacy data from the initial roll‐in cohort of the REBALANCE‐HF trial.

Methods and results

The open‐label (roll‐in) arm of REBALANCE‐HF will enrol up to 30 patients, followed by the randomized, sham‐controlled portion of the trial (up to 80 additional patients). Patients with HF, left ventricular ejection fraction (LVEF) ≥50%, and invasive peak exercise pulmonary capillary wedge pressure (PCWP) ≥25 mmHg underwent SAVM. Baseline and follow‐up assessments included resting and exercise PCWP, New York Heart Association (NYHA) class, Kansas City Cardiomyopathy Questionnaire (KCCQ), 6‐min walk test, and N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP). Efficacy and safety were assessed at 1 and 3 months. Here we report on the first 18 patients with HFpEF that have been enrolled into the roll‐in, open‐label arm of the study across nine centres; 14 (78%) female; 16 (89%) in NYHA class III; and median (interquartile range) age 75.2 (68.4–81) years, LVEF 61.0 (56.0–63.2)%, and average (standard deviation) 20 W exercise PCWP 36.4 (±8.6) mmHg. All 18 patients were successfully treated. Three non‐serious moderate device/procedure‐related adverse events were reported. At 1‐month, the mean PCWP at 20 W exercise decreased from 36.4 (±8.6) to 28.9 (±7.8) mmHg (p < 0.01), NYHA class improved by at least one class in 33% of patients (p = 0.02) and KCCQ score improved by 22.1 points (95% confidence interval 9.4–34.2) (p < 0.01).

Conclusion

The preliminary open‐label results from the multicentre REBALANCE‐HF roll‐in cohort support the safety and efficacy of SAVM in HFpEF. The findings require confirmation in the ongoing randomized, sham‐controlled portion of the trial.

Venous Tone and Stressed Blood Volume in Heart Failure: JACC Review Topic of the Week

A number of pathologic processes contribute to the elevation in cardiac filling pressures in heart failure (HF), including myocardial dysfunction and primary volume overload. In this review, we discuss the important role of the venous system and the concepts of stressed blood volume and unstressed blood volume. We review how regulation of venous tone modifies the distribution of blood between these 2 functional compartments, the physical distribution of blood between the pulmonary and systemic circulations, and how these relate to the hemodynamic abnormalities observed in HF. Finally, we review recently applied methods for estimating stressed blood volume and how they are being applied to the results of clinical studies to provide new insights into resting and exercise hemodynamics and therapeutics for HF.

Targeting Preload in Heart Failure: Splanchnic Nerve Blockade and Beyond

Preload augmentation represents a critical mechanism for the cardiovascular system to increase effective circulating blood volume to increase cardiac filling pressures and, subsequently, for the heart to increase cardiac output. The splanchnic vascular compartment is the primary source of vascular capacity and thus the primary target for preload recruitment in humans. Under normal conditions, sympathetic stimulation of these primary venous vessels promotes the shift of blood from the splanchnic to the thoracic compartment and elevates preload and cardiac output. However, in heart failure, since filling pressures may be elevated at rest due to decreased venous capacitance, incremental recruitment of preload to enhance cardiac output may exacerbate congestion and limit exercise capacity. Accordingly, recent attention has focused on therapies designed to regulate splanchnic vascular redistribution to improve cardiac filling pressures and patient-centered outcomes such as quality of life and exercise capacity in patients with heart failure. In this review, we discuss the relevance of splanchnic circulation as a venous reservoir, the contribution of stressed blood volume to heart failure pathogenesis, and the implications for pharmacological therapeutic interventions to prevent heart failure decompensation. Further, we review emerging device-based approaches for cardiac preload reduction such as partial/complete occlusion of the superior vena cava or the inferior vena cava.

Device Therapy in Chronic Heart Failure: JACC State-of-the-Art Review

The regulatory landscape for device-based heart failure (HF) therapies has seen a major shift in the last 7 years. In 2013, the U.S. Food and Drug Administration released guidance for early feasibility and first-in-human studies, thereby encouraging device innovation, and in 2016 the U.S. Congress authorized the Breakthrough Devices Program to expedite access for Americans to innovative devices indicated for diagnosis and treatment of serious illnesses, such as HF. Since December 2016, there has been an increase in the number of HF devices for which manufacturers are seeking approval through the breakthrough designation pathway. This has led to a rapid uptake in the development and evaluation of device-based HF therapies. This article reviews the current and future landscape of device therapies for chronic HF and associated comorbidities and the regulatory environment that is driving current and future innovation.

Surgical ablation of the right greater splanchnic nerve for the treatment of heart failure with preserved ejection fraction: first-in-human clinical trial

AIMS

Inappropriate control of blood volume redistribution may be a mechanism responsible for exercise intolerance in heart failure with preserved ejection fraction (HFpEF). We propose to address this underlying pathophysiology with selective blockade of sympathetic signalling to the splanchnic circulation by surgical ablation of the right greater splanchnic nerve (GSN).

METHODS AND RESULTS

In a single-arm, prospective, two-centre trial, 10 patients with HFpEF (50% male, mean age 70 ± 3 years) all with New York Heart Association (NYHA) class III, left ventricular ejection fraction >40%, pulmonary capillary wedge pressure (PCWP) ≥15 mmHg at rest or ≥25 mmHg with supine cycle ergometry, underwent ablation of the right GSN via thoracoscopic surgery. Patients were evaluated at baseline, 1, 3, 6 and 12 months after the procedure. The primary endpoint was a reduction in exercise PCWP at 3 months. There were no adverse events related to the blockade of the nerve during 12-month follow-up but three patients had significant peri-procedural adverse events related to the surgical procedure itself. At 3 months post-GSN ablation, patients demonstrated a reduction in 20 W exercise PCWP when compared to baseline [-4.5 mmHg (95% confidence interval, CI -14 to -2); P = 0.0059], which carried over to peak exercise [-5 mmHg (95% CI -11 to 0; P = 0.016). At 12 months, improvements were seen in NYHA class [3 (3) vs. 2 (1, 2); P = 0.0039] and quality of life assessed with the Minnesota Living with Heart Failure Questionnaire [60 (51, 71) vs. 22 (16, 27); P = 0.0039].

CONCLUSION

In this first-in-human study, GSN ablation in HFpEF proved to be feasible, with a suggestion of reduced cardiac filling pressure during exercise, improved quality of life and exercise capacity.