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.

Splanchnic nerve modulation in heart failure: mechanistic overview, initial clinical experience, and safety considerations.

Volume recruitment from the splanchnic compartment is an important physiological response to stressors such as physical activity and blood loss. In the setting of heart failure (HF), excess fluid redistribution from this compartment leads to increased cardiac filling pressures with limitation in exercise capacity. Recent evidence suggests that blocking neural activity of the greater splanchnic nerve (GSN) could have significant benefits in some patients with HF by reducing cardiac filling pressures and improving exercise capacity. However, to date the long-term safety of splanchnic nerve modulation (SNM) in the setting of HF is unknown. SNM is currently used in clinical practice to alleviate some forms of chronic abdominal pain. A systematic review of the series where permanent SNM was used as a treatment for chronic abdominal pain indicates that permanent SNM is well tolerated, with side-effects limited to transient diarrhoea or abdominal colic and transient hypotension. The pathophysiological role of the GSN in volume redistribution, the encouraging findings of acute and chronic pilot SNM studies and the safety profile from permanent SNM for pain provides a strong basis for continued efforts to study this therapeutic target in HF.

Increasing Blood Pressure by Greater Splanchnic Nerve Stimulation: a Feasibility Study.

The splanchnic vascular compartment is the major reservoir for intravascular blood volume, and dysregulation of the compartment was implicated in a series of cardiovascular conditions. We explored feasibility and effectiveness of an implantable cuff system on the greater splanchnic nerve (GSN) in healthy canines for short- and long-term neuromodulation to affect the circulation. Five mongrel hounds underwent minimally invasive right-sided unilateral GSN cuff placement. All animals underwent same day GSN stimulation and repeat stimulation at 9-30 days. Stimulation parameter optimization was conducted both acutely and chronically. Parameters ranged from 1-250 Hz, 0.25 mA-35 mA, 0.1-0.5 ms, and 30-s pulse duration. Two animals were survived for 9 days and 3 animals for 30 days. Stimulation of the right GSN increased mean arterial blood pressure by 36.9 mmHg ± 13.4 (p < 0.0001), central venous pressure by 6.9 mmHg ± 1.7 (p < 0.0001), and mean pulmonary arterial pressure by 6.3 mmHg ± 2.0 (p < 0.0001). Peak effects were observed within 30 s, and magnitude of effects was comparable between stimulation cycles (p = 0.4). Stimulation-induced changes in hemodynamics were independent of afferent nerve fibers (pain response) or the adrenal gland. Necropsy showed no evidence of nerve damage on histologic studies up to 30 days after implantation. GSN stimulation via an implanted nerve cuff provided a reproducible and rapid method to increase arterial, central venous, and pulmonary arterial pressures. The neuromodulation cuff was well tolerated and elicited a response up to 30 days after implantation. The clinical application of GSN stimulation as a tool to change central and peripheral cardiovascular hemodynamics needs to be explored.

Minimally invasive transtracheal cardiac plexus block for sympathetic neuromodulation.

BACKGROUND: Bilateral thoracoscopic stellectomy has antiarrhythmic effects, but the procedure is invasive with associated morbidity. Sympathetic nerves from both stellate ganglia form the deep cardiac plexus (CP) in the aortopulmonary window, anterior to the trachea. OBJECTIVE: The purpose of this study was to demonstrate a novel and minimally invasive transtracheal approach to block the CP in porcine models. METHODS: In 12 Yorkshire pigs, right (RSG) and left (LSG) stellate ganglia were electrically stimulated and sympathetic baseline response recorded (hemodynamic parameters and T-wave pattern). Aortopulmonary window was accessed transtracheally with endobronchial ultrasound guidance, and local stimulation of CP confirmed the location. Injection of 1% lidocaine (n = 10) or saline solution (n = 2) was performed, and RSG and LSG responses were re-evaluated and compared with baseline. RESULTS: Transtracheal lidocaine injection into the CP successfully blocked bilateral sympathetic induced changes (%) in T-wave amplitude (282.8% ± 152.2% vs 20.1% ± 16.5%; P <.001 [LSG]; 338.9% ± 189.8% vs 28% ± 18.3%; P <.001 [RSG]), Tp-Te interval (87.9% ± 37.2% vs 6.9% ± 6.7%; P <.001 [LSG]; 32.6% ± 27.4% vs 6.9% ± 4.7%; P <.035 [RSG]), and left ventricular dP/dTmax (148.3% ± 108.5% vs 16.5% ± 13.4%; P <.001 [LSG]; 243.1% ± 105.2% vs 19.0% ± 12.4%; P <.001 [RSG]). RSG-induced elevations of systemic, left ventricular, and pulmonary arterial pressures were blocked by lidocaine injection into CP (P <.005 for all comparisons). Stellate ganglia response was not affected in sham studies. No complications were observed during the procedures. CONCLUSION: Minimally invasive transtracheal injection of lidocaine into the CP blocked the sympathetic response of either RSG and LSG. Transtracheal assessment of CP may allow for minimally invasive and selective ablation of cardiac innervation, extending the cardiac sympathectomy denervation benefits to those not suitable for surgery.