Coronary Sinus Neuropeptide Y Levels and Adverse Outcomes in Patients With Stable Chronic Heart Failure

Historical Perspective of the Cardiac Autonomic Nervous System

The contemporary history of the cardiac autonomic nervous system includes early descriptions of neuroanatomy in the 19th century, followed by an understanding of the physiologic determinants of neurocardiology in the 20th century. Neurology and cardiology preceded the arrival of clinical cardiac electrophysiology, a specialized field in medicine devoted to the diagnosis and treatment of cardiac arrhythmias. The rapid growth in pharmacology, ablation, pacing and defibrillation, associated with significant technological breakthroughs, have resulted in new opportunities for neuromodulation in the 21st century. Small changes in autonomic tone can potentially provide important therapeutic benefits for patients with cardiac and arrhythmia disorders.

Subarachnoid haemorrhage-induced reversible cardiac dysfunction: time course and potential mechanisms

AIMS

Cardiac dysfunction is commonly observed in patients with subarachnoid haemorrhage (SAH). However, the specific timeline of cardiac remodelling and the underlying mechanisms responsible for this effect following SAH remain unknown. This study aims to explore the impact of SAH on cardiac dysfunction and its potential mechanisms over time.

METHODS AND RESULTS

In Protocol 1, we investigated cardiac function and potential mechanisms in a Sprague-Dawley rat model of SAH at six time points (baseline and Days 1, 3, 7, 14, and 28) while exploring the underlying mechanisms. Our assessments included the haemodynamic profile, echocardiography, and the concentrations of plasma biomarkers at various time points post-SAH. We determined neuropeptide Y (NPY) 1-5 receptor protein expression levels through western blotting. In Protocol 2, we administered an NPY1 receptor antagonist to evaluate the effects of cardiac dysfunction induced by SAH on Day 3. In Protocol 1, SAH gradually provoked cardiac systolic dysfunction during the acute phase, reaching its peak on Day 3 without concurrent alterations in wall thickness. However, no significant changes were observed from Days 14 to 28 compared with Day 0. The changes in cardiac dysfunction were consistent with myocardial injury, inflammatory biomarkers, and NPY levels. SAH resulted in a heightened heart rate and systolic blood pressure, correlating with elevated epinephrine and norepinephrine levels. In Protocol 2, the administration of the NPY1 receptor antagonist effectively ameliorated cardiac dysfunction.

CONCLUSIONS

SAH induces transient cardiac dysfunction in the acute phase, and the underlying mechanisms for this response involve the NPY-NPY1 receptor pathway, otherwise known as catecholamines.

Coronary Sinus Metabolite 12,13-diHOME Is a Novel Biomarker for Left Atrial Remodeling in Patients With Atrial Fibrillation

BACKGROUND

12,13-dihydroxy-9Z-octadecenoic acid (12,13-diHOME) has shown potential in protecting against heart disease, but its relationship with atrial fibrillation (AF) remains unknown.

METHODS

Coronary sinus (CS) and femoral vein blood samplings were synchronously collected from AF and non-AF subjects (paroxysmal supraventricular tachycardia or idiopathic premature ventricular complexes) who underwent catheter ablation. First, untargeted metabolomic profiling was performed in a discovery cohort (including 12 AF and 12 non-AF subjects) to identify the most promising CS or femoral vein metabolite. Then, the selected metabolite was further measured in a validation cohort (including 119 AF and 103 non-AF subjects) to confirm its relationship with left atrium remodeling and 1-year postablation recurrence of AF. Finally, the biological function of the selected metabolite was validated in a rapid-paced cultured HL-1 atrial cardiomyocytes model.

RESULTS

Metabolomic analysis identified CS 12,13-diHOME as the most pronounced change metabolite correlated with left atrium remodeling in the discovery cohort. In the validation cohort, CS 12,13-diHOME was significantly lower in patients with AF than non-AF controls (84.32±20.13 versus 96.24±23.56 pg/mL; P<0.01), and associated with worse structural, functional, and electrical remodeling of left atrium. Multivariable regression analyses further demonstrated that decreased CS 12,13-diHOME was an independent predictor of 1-year postablation recurrence of AF (odds ratio, 0.754 [95% CI, 0.648-0.920]; P=0.005). Biological function validations showed that 12,13-diHOME treatment significantly protect the cell viability, improved the expression of MHC (myosin heavy chain) and Cav1.2 (L-type calcium channel α1c), and attenuated mitochondrial damage in the rapid-paced cultured HL-1 cardiomyocytes model.

CONCLUSIONS

CS metabolite 12,13-diHOME is decreased in patients with AF and can serve as a novel biomarker for left atrium remodeling.

Sympathetic Neural Control at Rest and During the Cold Pressor Test in Patients With Heart Failure With Preserved Ejection Fraction

BACKGROUND

We tested the hypothesis that patients with heart failure with preserved ejection fraction (HFpEF) would have greater muscle sympathetic nerve activity (MSNA) at rest and sympathetic reactivity during a cold pressor test compared with non-heart failure controls. Further, given the importance of the baroreflex modulation of MSNA in the control of blood pressure (BP), we hypothesized that patients with HFpEF would exhibit a reduced sympathetic baroreflex sensitivity.

METHODS

Twenty-eight patients with HFpEF and 44 matched controls (mean±SD: 71±8 versus 70±7 years; 9 men/19 women versus 16 men/28 women) were studied. BP, heart rate, and MSNA (microneurography) were measured during 6 to 10 minutes of supine rest and the 2-minute cold pressor test. Spontaneous sympathetic baroreflex sensitivity was assessed during supine rest.

RESULTS

Patients with HFpEF had higher resting MSNA burst frequency (39±14 versus 31±12 bursts/min; P=0.020) and lower sympathetic baroreflex sensitivity (-2.83±0.76 versus -3.57±1.19 bursts/100 heartbeats/mm Hg; P=0.019) than controls, but burst incidence was not different between groups (56±19 versus 50±20 bursts/100 heartbeats; P=0.179). During the cold pressor test, increases in MSNA indices did not differ between groups (P=0.135-0.998), but patients had a smaller increase in diastolic BP (Δ4±6 versus Δ14±11 mm Hg; P<0.001) compared with controls.

CONCLUSIONS

Despite augmented resting MSNA burst frequency, burst incidence was not significantly different between groups, and sympathetic baroreflex sensitivity was reduced in patients with HFpEF. Furthermore, patients had preserved sympathetic reactivity but attenuated diastolic BP responses during the cold pressor test. These data suggest that, during physiological stress, sympathetic reactivity is intact, but the peripheral pathway for sympathetic vasoconstriction may be impaired in HFpEF.

Neuropeptide Y is elevated in heart failure and is an independent predictor of outcomes

AIMS

Neuropeptide Y (NPY) is the most abundant neuropeptide found in the heart and is released alongside norepinephrine following prolonged sympathetic activation, a process that is implicated in the pathophysiology of heart failure (HF). In patients with severely impaired left ventricular ejection fraction (LVEF) undergoing cardiac resynchronization therapy, higher levels of NPY measured in coronary sinus blood, are associated with poorer outcome. The aim was to examine the association of peripheral venous NPY levels and outcomes in a HF population with a range of LVEF, using a highly sensitive and specific assay.

METHODS AND RESULTS

The association between NPY and the composite outcome of cardiovascular death or HF hospitalization, its components, and all-cause mortality was examined using Cox regression analyses among 833 patients using a threshold of elevated NPY identified through binary recursive partitioning adjusted for prognostic variables including estimated glomerular filtration rate (eGFR), ejection fraction and B-type natriuretic peptide (BNP). The mean value of NPY was 25.8 ± 18.2 pg/ml. Patients with high NPY levels (≥29 pg/ml) compared with low values were older (73 ± 10 vs. 71 ± 11 years), more often male (58.5% vs. 55.6%), had higher BNP levels (583 [261-1096] vs. 440 [227-829] pg/ml), lower eGFR (46.4 ± 13.9 vs. 52.4 ± 11.7 ml/min/1.73 m2 ), and were more often treated with diuretics. There was no associated risk of HF hospitalization with NPY levels ≥29 vs. <29 pg/ml. Higher NPY levels were associated with a greater risk of cardiovascular and all-cause death (adjusted hazard ratio 1.56 [95% confidence interval 1.21-2.10], p = 0.003 and 1.30 [1.04-1.62], p = 0.02, respectively). There was no associated risk of HF hospitalization with higher NPY levels.

CONCLUSIONS

Peripherally measured NPY is an independent predictor of all-cause and cardiovascular death even after adjustment for other prognostic variables, including BNP.

Gβγ subunit signalling underlies neuropeptide Y-stimulated vasoconstriction in rat mesenteric and coronary arteries

BACKGROUND AND PURPOSE

Raised serum concentrations of the sympathetic co-transmitter neuropeptide Y (NPY) are linked to cardiovascular diseases. However, the signalling mechanism for vascular smooth muscle (VSM) constriction to NPY is poorly understood. Therefore, the present study investigated the mechanisms of NPY-induced vasoconstriction in rat small mesenteric (RMA) and coronary (RCA) arteries.

EXPERIMENTAL APPROACH

Third-order mesenteric or intra-septal arteries from male Wistar rats were assessed in wire myographs for isometric tension, VSM membrane potential and VSM intracellular Ca2+ events.

KEY RESULTS

NPY stimulated concentration-dependent vasoconstriction in both RMA and RCA, which was augmented by blocking NO synthase or endothelial denudation in RMA. NPY-mediated vasoconstriction was blocked by the selective Y1 receptor antagonist BIBO 3304 and Y1 receptor protein expression was detected in both the VSM and endothelial cells in RMA and RCA. The selective Gβγ subunit inhibitor gallein and the PLC inhibitor U-73122 attenuated NPY-induced vasoconstriction. Signalling via the Gβγ-PLC pathway stimulated VSM Ca2+ waves and whole-field synchronised Ca2+ flashes in RMA and increased the frequency of Ca2+ flashes in myogenically active RCA. Furthermore, in RMA, the Gβγ pathway linked NPY to VSM depolarization and generation of action potential-like spikes associated with intense vasoconstriction. This depolarization activated L-type voltage-gated Ca2+ channels, as nifedipine abolished NPY-mediated vasoconstriction.

CONCLUSIONS AND IMPLICATIONS

These data suggest that the Gβγ subunit, which dissociates upon Y1 receptor activation, initiates VSM membrane depolarization and Ca2+ mobilisation to cause vasoconstriction. This model may help explain the development of microvascular vasospasm during raised sympathetic nerve activity.

Associations of polyneuropathy with risk of all-cause and cardiovascular mortality, cardiovascular disease events stratified by diabetes status

AIMS/INTRODUCTION

We investigated the association of polyneuropathy (PN) with all-cause and cardiovascular (CV) mortality and with cardiovascular disease (CVD) events stratified by diabetes status.

MATERIALS AND METHODS

This prospective cohort study used the UK Biobank. Polyneuropathy was defined based on nurse-led interviews or ICD codes for polyneuropathy. Cox proportional hazards models were used to investigate the association of polyneuropathy with clinical outcomes.

RESULTS

A total of 459,127 participants were included in the analysis. Polyneuropathy was significantly associated with all-cause and cardiovascular mortality, and with CVD events even after adjusting for CVD risk factors across all diabetes statuses. Metabolic parameters HbA1c , waist circumference, BMI and the inflammatory parameter C-reactive protein showed significant mediation effects for the association between polyneuropathy and CVD. Adherence to a favorable lifestyle was associated with a lower risk of all-cause and cardiovascular mortality regardless of polyneuropathy status.

CONCLUSIONS

Polyneuropathy was associated with all-cause and cardiovascular mortality, and with CVD events in subjects with diabetes or prediabetes, even those having normal glucose tolerance. This study suggests the importance of polyneuropathy as a risk factor for death and highlights the necessity of early diagnosis and lifestyle intervention for those with type 2 diabetes and polyneuropathy.

Protein kinase A: A potential marker of sympathovagal imbalance in heart failure

Mitigation of cardiac autonomic dysregulation by neuromodulation technologies is emerging as a new therapeutic modality of heart failure (HF). This recent progress has necessitated the identification of a biomarker for the quantification of sympathovagal balance, the potential target of 'neuromodulation' strategies. The currently available autonomic nervous system assessment parameters do not truly reflect the sympathovagal balance of the ventricle. Protein kinase A (PKA) is an intracellular enzyme that plays a major role in the pathophysiology of functional and structural ventricular remodeling in HF. Interestingly, sympathetic and parasympathetic activations exert reciprocal influence on the activity of PKA. The current review attempts to evaluate the potential concept and feasibility of using in vitro assessment of PKA activity as a marker of sympathovagal balance in HF.

Sympathetic Modulation in Cardiac Arrhythmias: Where We Stand and Where We Go

The nuance of autonomic cardiac control has been studied for more than 400 years, yet little is understood. This review aimed to provide a comprehensive overview of the current understanding, clinical implications, and ongoing studies of cardiac sympathetic modulation and its anti-ventricular arrhythmias' therapeutic potential. Molecular-level studies and clinical studies were reviewed to elucidate the gaps in knowledge and the possible future directions for these strategies to be translated into the clinical setting. Imbalanced sympathoexcitation and parasympathetic withdrawal destabilize cardiac electrophysiology and confer the development of ventricular arrhythmias. Therefore, the current strategy for rebalancing the autonomic system includes attenuating sympathoexcitation and increasing vagal tone. Multilevel targets of the cardiac neuraxis exist, and some have emerged as promising antiarrhythmic strategies. These interventions include pharmacological blockade, permanent cardiac sympathetic denervation, temporal cardiac sympathetic denervation, etc. The gold standard approach, however, has not been known. Although neuromodulatory strategies have been shown to be highly effective in several acute animal studies with very promising results, the individual and interspecies variation between human autonomic systems limits the progress in this young field. There is, however, still much room to refine the current neuromodulation therapy to meet the unmet need for life-threatening ventricular arrhythmias.

Autonomic nervous system and cardiac neuro-signaling pathway modulation in cardiovascular disorders and Alzheimer's disease

The heart is a functional syncytium controlled by a delicate and sophisticated balance ensured by the tight coordination of its several cell subpopulations. Accordingly, cardiomyocytes together with the surrounding microenvironment participate in the heart tissue homeostasis. In the right atrium, the sinoatrial nodal cells regulate the cardiac impulse propagation through cardiomyocytes, thus ensuring the maintenance of the electric network in the heart tissue. Notably, the central nervous system (CNS) modulates the cardiac rhythm through the two limbs of the autonomic nervous system (ANS): the parasympathetic and sympathetic compartments. The autonomic nervous system exerts non-voluntary effects on different peripheral organs. The main neuromodulator of the Sympathetic Nervous System (SNS) is norepinephrine, while the principal neurotransmitter of the Parasympathetic Nervous System (PNS) is acetylcholine. Through these two main neurohormones, the ANS can gradually regulate cardiac, vascular, visceral, and glandular functions by turning on one of its two branches (adrenergic and/or cholinergic), which exert opposite effects on targeted organs. Besides these neuromodulators, the cardiac nervous system is ruled by specific neuropeptides (neurotrophic factors) that help to preserve innervation homeostasis through the myocardial layers (from epicardium to endocardium). Interestingly, the dysregulation of this neuro-signaling pathway may expose the cardiac tissue to severe disorders of different etiology and nature. Specifically, a maladaptive remodeling of the cardiac nervous system may culminate in a progressive loss of neurotrophins, thus leading to severe myocardial denervation, as observed in different cardiometabolic and neurodegenerative diseases (myocardial infarction, heart failure, Alzheimer's disease). This review analyzes the current knowledge on the pathophysiological processes involved in cardiac nervous system impairment from the perspectives of both cardiac disorders and a widely diffused and devastating neurodegenerative disorder, Alzheimer's disease, proposing a relationship between neurodegeneration, loss of neurotrophic factors, and cardiac nervous system impairment. This overview is conducive to a more comprehensive understanding of the process of cardiac neuro-signaling dysfunction, while bringing to light potential therapeutic scenarios to correct or delay the adverse cardiovascular remodeling, thus improving the cardiac prognosis and quality of life in patients with heart or neurodegenerative disorders.

Tiered Sympathetic Control of Cardiac Function Revealed by Viral Tracing and Single Cell Transcriptome Profiling

The cell bodies of postganglionic sympathetic neurons innervating the heart primarily reside in the stellate ganglion (SG), alongside neurons innervating other organs and tissues. Whether cardiac-innervating stellate ganglionic neurons (SGNs) exhibit diversity and distinction from those innervating other tissues is not known. To identify and resolve the transcriptomic profiles of SGNs innervating the heart we leveraged retrograde tracing techniques using adeno-associated virus (AAV) expressing fluorescent proteins (GFP or Td-tomato) with single cell RNA sequencing. We investigated electrophysiologic, morphologic, and physiologic roles for subsets of cardiac-specific neurons and found that three of five adrenergic SGN subtypes innervate the heart. These three subtypes stratify into two subpopulations; high (NA1a) and low (NA1b and NA1c) Npy-expressing cells, exhibit distinct morphological, neurochemical, and electrophysiologic characteristics. In physiologic studies in transgenic mouse models modulating NPY signaling, we identified differential control of cardiac responses by these two subpopulations to high and low stress states. These findings provide novel insights into the unique properties of neurons responsible for cardiac sympathetic regulation, with implications for novel strategies to target specific neuronal subtypes for sympathetic blockade in cardiac disease.

Autonomic imbalance and atrial ectopic activity-a pathophysiological and clinical view

The heart is one of the most richly innervated organs and the impact of the complex cardiac autonomic network on atrial electrophysiology and arrhythmogenesis, including on atrial ectopy, is widely recognized. The aim of this review is to discuss the main mechanisms involved in atrial ectopic activity. An overview of the anatomic and physiological aspects of the cardiac autonomic nervous system is provided as well as a discussion of the main pathophysiological pathways linking autonomic imbalance and atrial ectopic activity. The most relevant data on cardiac neuromodulation strategies are emphasized. Unanswered questions and hotspots for future research are also identified.

Metrics of high cofluctuation and entropy to describe control of cardiac function in the stellate ganglion

Stellate ganglia within the intrathoracic cardiac control system receive and integrate central, peripheral, and cardiopulmonary information to produce postganglionic cardiac sympathetic inputs. Pathological anatomical and structural remodeling occurs within the neurons of the stellate ganglion (SG) in the setting of heart failure (HF). A large proportion of SG neurons function as interneurons whose networking capabilities are largely unknown. Current therapies are limited to targeting sympathetic activity at the cardiac level or surgical interventions such as stellectomy, to treat HF. Future therapies that target the SG will require understanding of their networking capabilities to modify any pathological remodeling. We observe SG networking by examining cofluctuation and specificity of SG networked activity to cardiac cycle phases. We investigate network processing of cardiopulmonary transduction by SG neuronal populations in porcine with chronic pacing-induced HF and control subjects during extended in-vivo extracellular microelectrode recordings. We find that information processing and cardiac control in chronic HF by the SG, relative to controls, exhibits: (i) more frequent, short-lived, high magnitude cofluctuations, (ii) greater variation in neural specificity to cardiac cycles, and (iii) neural network activity and cardiac control linkage that depends on disease state and cofluctuation magnitude.

Stellate Ganglia and Cardiac Sympathetic Overactivation in Heart Failure

Heart failure (HF) is a major public health problem worldwide, especially coronary heart disease (myocardial infarction)-induced HF with reduced ejection fraction (HFrEF), which accounts for over 50% of all HF cases. An estimated 6 million American adults have HF. As a major feature of HF, cardiac sympathetic overactivation triggers arrhythmias and sudden cardiac death, which accounts for nearly 50–60% of mortality in HF patients. Regulation of cardiac sympathetic activation is highly integrated by the regulatory circuitry at multiple levels, including afferent, central, and efferent components of the sympathetic nervous system. Much evidence, from other investigators and us, has confirmed the afferent and central neural mechanisms causing sympathoexcitation in HF. The stellate ganglion is a peripheral sympathetic ganglion formed by the fusion of the 7th cervical and 1st thoracic sympathetic ganglion. As the efferent component of the sympathetic nervous system, cardiac postganglionic sympathetic neurons located in stellate ganglia provide local neural coordination independent of higher brain centers. Structural and functional impairments of cardiac postganglionic sympathetic neurons can be involved in cardiac sympathetic overactivation in HF because normally, many effects of the cardiac sympathetic nervous system on cardiac function are mediated via neurotransmitters (e.g., norepinephrine) released from cardiac postganglionic sympathetic neurons innervating the heart. This review provides an overview of cardiac sympathetic remodeling in stellate ganglia and potential mechanisms and the role of cardiac sympathetic remodeling in cardiac sympathetic overactivation and arrhythmias in HF. Targeting cardiac sympathetic remodeling in stellate ganglia could be a therapeutic strategy against malignant cardiac arrhythmias in HF.

Neuropeptide Y Promotes Human M2 Macrophage Polarization and Enhances p62/SQSTM1-Dependent Autophagy and NRF2 Activation

Neuropeptide Y (NPY) is an abundantly expressed peptide capable of modulating innate and adaptive immune responses and regulating chemotaxis and cytokine secretion by macrophages. Abnormal regulation of NPY is involved in the development of atherosclerosis. The inflammatory infiltrate within atherosclerotic plaque is characterized by accumulation of macrophages, which are subject to reprogram their phenotypes in response to environmental signals. Macrophage number and phenotype influence plaque fate. Here, we investigated the effect of NPY on the changes in phenotype and functions of human macrophages, from the pro-inflammatory phenotype M1 to the reparative M2, indicative of atherosclerosis regression or stabilization. Human monocytes were differentiated in vitro into macrophages with M-CSF (M0) and polarized towards an M1 phenotype with IFN-γ plus LPS M(IFN-γ/LPS) or M2 with IL-10 (M IL-10) and further challenged with NPY (10-7-10-9 M) for 8-36 h. Cell phenotype and functions were analyzed by immunofluorescence and immunochemical analyses. NPY affected macrophage surface markers and secretome profile expression, thus shifting macrophages toward an M2-like phenotype. NPY also prevented the impairment of endocytosis triggered by the oxysterol 7-keto-cholesterol (7KC) and prevented 7KC-induced foam cell formation by reducing the lipid droplet accumulation in M0 macrophages. NPY-treated M0 macrophages enhanced the autophagosome formation by upregulating the cell content of the autophagy markers LC3-II and p62-SQSTM1, increased activation of the anti-oxidative transcription factor NRF2 (NF-E2-related factor 2), and subsequently induced its target gene HMOX1 that encodes heme oxygenase-1. Our findings indicate that NPY has a cytoprotective effect with respect to the progression of the inflammatory pathway, both enhancing p62/SQSTM1-dependent autophagy and the NRF2-antioxidant signaling pathway in macrophages. NPY signaling may have a crucial role in tissue homeostasis in host inflammatory responses through the regulation of macrophage balance and functions within atherosclerosis.

Saxagliptin Cardiotoxicity in Chronic Heart Failure: The Role of DPP4 in the Regulation of Neuropeptide Tone

Dipeptidyl-peptidase-4 (DPP4) inhibitors are novel medicines for diabetes. The SAVOR-TIMI-53 clinical trial revealed increased heart-failure-associated hospitalization in saxagliptin-treated patients. Although this side effect could limit therapeutic use, the mechanism of this potential cardiotoxicity is unclear. We aimed to establish a cellular platform to investigate DPP4 inhibition and the role of its neuropeptide substrates substance P (SP) and neuropeptide Y (NPY), and to determine the expression of DDP4 and its neuropeptide substrates in the human heart. Western blot, radio-, enzyme-linked immuno-, and RNA scope assays were performed to investigate the expression of DPP4 and its substrates in human hearts. Calcein-based viability measurements and scratch assays were used to test the potential toxicity of DPP4 inhibitors. Cardiac expression of DPP4 and NPY decreased in heart failure patients. In human hearts, DPP4 mRNA is detectable mainly in cardiomyocytes and endothelium. Treatment with DPP4 inhibitors alone/in combination with neuropeptides did not affect viability but in scratch assays neuropeptides decreased, while saxagliptin co-administration increased fibroblast migration in isolated neonatal rat cardiomyocyte-fibroblast co-culture. Decreased DPP4 activity takes part in the pathophysiology of end-stage heart failure. DPP4 compensates against the elevated sympathetic activity and altered neuropeptide tone. Its inhibition decreases this adaptive mechanism, thereby exacerbating myocardial damage.

Neuropeptide-Y Levels in ST-Segment-Elevation Myocardial Infarction: Relationship With Coronary Microvascular Function, Heart Failure, and Mortality

Background

The sympathetic cotransmitter, neuropeptide Y (NPY), is released into the coronary sinus during ST‐segment–elevation myocardial infarction and can constrict the coronary microvasculature. We sought to establish whether peripheral venous (PV) NPY levels, which are easy to obtain and measure, are associated with microvascular obstruction, myocardial recovery, and prognosis.

Methods and Results

NPY levels were measured immediately after primary percutaneous coronary intervention and compared with angiographic and cardiovascular magnetic resonance indexes of microvascular function. Patients were prospectively followed up for 6.4 (interquartile range, 4.1–8.0) years. PV (n=163) and coronary sinus (n=68) NPY levels were significantly correlated (r=0.92; P<0.001) and associated with multiple coronary and imaging parameters of microvascular function and infarct size (such as coronary flow reserve, acute myocardial edema, left ventricular ejection fraction, and late gadolinium enhancement 6 months later). We therefore assessed the prognostic value of PV NPY during follow‐up, where 34 patients (20.7%) developed heart failure or died. Kaplan‐Meier survival analysis demonstrated that high PV NPY levels (>21.4 pg/mL by binary recursive partitioning) were associated with increased incidence of heart failure and mortality (hazard ratio, 3.49 [95% CI, 1.65–7.4]; P<0.001). This relationship was maintained after adjustment for age, cardiovascular risk factors, and previous myocardial infarction.

Conclusions

Both PV and coronary sinus NPY levels correlate with microvascular function and infarct size after ST‐segment–elevation myocardial infarction. PV NPY levels are associated with the subsequent development of heart failure or mortality and may therefore be a useful prognostic marker. Further research is required to validate these findings.

Research Opportunities in Autonomic Neural Mechanisms of Cardiopulmonary Regulation: A Report From the National Heart, Lung, and Blood Institute and the National Institutes of Health Office of the Director Workshop

This virtual workshop was convened by the National Heart, Lung, and Blood Institute, in partnership with the Office of Strategic Coordination of the Office of the National Institutes of Health Director, and held September 2 to 3, 2020. The intent was to assemble a multidisciplinary group of experts in basic, translational, and clinical research in neuroscience and cardiopulmonary disorders to identify knowledge gaps, guide future research efforts, and foster multidisciplinary collaborations pertaining to autonomic neural mechanisms of cardiopulmonary regulation. The group critically evaluated the current state of knowledge of the roles that the autonomic nervous system plays in regulation of cardiopulmonary function in health and in pathophysiology of arrhythmias, heart failure, sleep and circadian dysfunction, and breathing disorders. Opportunities to leverage the Common Fund's SPARC (Stimulating Peripheral Activity to Relieve Conditions) program were characterized as related to nonpharmacologic neuromodulation and device-based therapies. Common themes discussed include knowledge gaps, research priorities, and approaches to develop novel predictive markers of autonomic dysfunction. Approaches to precisely target neural pathophysiological mechanisms to herald new therapies for arrhythmias, heart failure, sleep and circadian rhythm physiology, and breathing disorders were also detailed.

The feasibility and safety of a simple method for coronary sinus blood sampling during catheter ablation of arrhythmias

Background

Coronary sinus (CS) blood sampling gives an insight into the localized pathophysiology of heart diseases. However, additional specifically-designed or modified catheters were needed in most previous studies, making the convenience of clinical application unsatisfactory. This study aimed to introduce a simple method for CS blood sampling without using additional catheters during catheter ablation (CA) of arrhythmias, and to investigate its feasibility and safety.

Methods

A total of 119 patients undergoing CA were prospectively enrolled, including 25 with paroxysmal supraventricular tachycardia (PSVT), 30 with premature ventricular complexes (PVC), and 64 with atrial fibrillation (AF). Cannulation and sampling of CS was performed via the femoral vein using a conventional 8F SR0^TM or 8.5F SL1^TM introducer sheath (St. Jude Medical) guided by a 6F steerable diagnostic catheter (St. Jude Medical). The success rate and any suspicious complications were recorded. Untargeted liquid chromatograph-mass spectrometer (LC-MS)-based metabonomics of CS samples versus peripheral venous samples were also performed.

Results

CS blood samples were successfully collected from 114 patients, with an overall success rate of 95.8%. Among patients with different arrhythmias, the success rates were similar, with 96.0% in PSVT, 96.7% in PVC, and 95.3% in AF (P=0.223). Adverse events occurred in four (3.4%) patients, including two patients with occasional atrial ectopic beats without causing any discomfort, and two patients with new-onset paroxysmal AF lasting for about 2 min. No serious complications were noted. Metabonomics analysis showed that CS samples provided a number of different metabolites (93 in PVST, 217 in PVC, and 109 in AF) versus peripheral samples.

Conclusions

Our method for CS blood sampling during CA is feasible and safe, and can provide useful cardiometabolic information that is significantly different from a peripheral sample.

What gets on the nerves of cardiac patients? Pathophysiological changes in cardiac innervation

The autonomic nervous system regulates cardiac function by balancing the actions of sympathetic and parasympathetic inputs to the heart. Intrinsic cardiac neurocircuits integrate these autonomic signals to fine-tune cardiac control, and sensory feedback loops regulate autonomic transmission in the face of external stimuli. These interconnected neural systems allow the heart to adapt to constantly changing circumstances that range from simple fluctuations in body position to running a marathon. The cardiac reflexes that serve to maintain homeostasis in health are disrupted in many disease states. This is often characterized by increased sympathetic and decreased parasympathetic transmission. Studies of cardiovascular disease reveal remodelling of cardiac neurocircuits at several functional and anatomical levels. Central circuits change so that sympathetic pathways become hyperactive, while parasympathetic circuits exhibit decreased activity. Peripheral sensory nerves also become hyperactive in disease, which increases patients' risk for poor cardiac outcomes. Injury and disease also alter the types of neurotransmitters and neuropeptides released by autonomic nerves in the heart, and can lead to regional hyperinnervation (increased nerve density) or denervation (decreased nerve density) of cardiac tissue. The mechanisms responsible for neural remodelling are not fully understood, but neurotrophins and inflammatory cytokines are likely involved. Areas of active investigation include the role of immune cells and inflammation in neural remodelling, as well as the role of glia in modulating peripheral neuronal activity. Our growing understanding of autonomic dysfunction in disease has facilitated development of new therapeutic strategies to improve health outcomes.

Autonomic modulation of ventricular electrical activity: recent developments and clinical implications

PURPOSE

This review aimed to provide a complete overview of the current stance and recent developments in antiarrhythmic neuromodulatory interventions, focusing on lifethreatening vetricular arrhythmias.

METHODS

Both preclinical studies and clinical studies were assessed to highlight the gaps in knowledge that remain to be answered and the necessary steps required to properly translate these strategies to the clinical setting.

RESULTS

Cardiac autonomic imbalance, characterized by chronic sympathoexcitation and parasympathetic withdrawal, destabilizes cardiac electrophysiology and promotes ventricular arrhythmogenesis. Therefore, neuromodulatory interventions that target the sympatho-vagal imbalance have emerged as promising antiarrhythmic strategies. These strategies are aimed at different parts of the cardiac neuraxis and directly or indirectly restore cardiac autonomic tone. These interventions include pharmacological blockade of sympathetic neurotransmitters and neuropeptides, cardiac sympathetic denervation, thoracic epidural anesthesia, and spinal cord and vagal nerve stimulation.

CONCLUSION

Neuromodulatory strategies have repeatedly been demonstrated to be highly effective and very promising anti-arrhythmic therapies. Nevertheless, there is still much room to gain in our understanding of neurocardiac physiology, refining the current neuromodulatory strategic options and elucidating the chronic effects of many of these strategic options.

Sympatho-adrenergic mechanisms in heart failure: new insights into pathophysiology

The sympathetic nervous system is activated in the setting of heart failure (HF) to compensate for hemodynamic instability. However, acute sympathetic surge or sustained high neuronal firing rates activates β-adrenergic receptor (βAR) signaling contributing to myocardial remodeling, dysfunction and electrical instability. Thus, sympatho-βAR activation is regarded as a hallmark of HF and forms pathophysiological basis for β-blocking therapy. Building upon earlier research findings, studies conducted in the recent decades have significantly advanced our understanding on the sympatho-adrenergic mechanism in HF, which forms the focus of this article. This review notes recent research progress regarding the roles of cardiac β2AR or α1AR in the failing heart, significance of β1AR-autoantibodies, and βAR signaling through G-protein independent signaling pathways. Sympatho-βAR regulation of immune cells or fibroblasts is specifically discussed. On the neuronal aspects, knowledge is assembled on the remodeling of sympathetic nerves of the failing heart, regulation by presynaptic α2AR of NE release, and findings on device-based neuromodulation of the sympathetic nervous system. The review ends with highlighting areas where significant knowledge gaps exist but hold promise for new breakthroughs.

Global REACH 2018: the adaptive phenotype to life with chronic mountain sickness and polycythaemia

KEY POINTS

Humans suffering from polycythaemia undergo multiple circulatory adaptations including changes in blood rheology and structural and functional vascular adaptations to maintain normal blood pressure and vascular shear stresses, despite high blood viscosity. During exercise, several circulatory adaptations are observed, especially involving adrenergic and non-adrenergic mechanisms within non-active and active skeletal muscle to maintain exercise capacity, which is not observed in animal models. Despite profound circulatory stress, i.e. polycythaemia, several adaptations can occur to maintain exercise capacity, therefore making early identification of the disease difficult without overt symptomology. Pharmacological treatment of the background heightened sympathetic activity may impair the adaptive sympathetic response needed to match local oxygen delivery to active skeletal muscle oxygen demand and therefore inadvertently impair exercise capacity.

ABSTRACT

Excessive haematocrit and blood viscosity can increase blood pressure, cardiac work and reduce aerobic capacity. However, past clinical investigations have demonstrated that certain human high-altitude populations suffering from excessive erythrocytosis, Andeans with chronic mountain sickness, appear to have phenotypically adapted to life with polycythaemia, as their exercise capacity is comparable to healthy Andeans and even with sea-level inhabitants residing at high altitude. By studying this unique population, which has adapted through natural selection, this study aimed to describe how humans can adapt to life with polycythaemia. Experimental studies included Andeans with (n = 19) and without (n = 17) chronic mountain sickness, documenting exercise capacity and characterizing the transport of oxygen through blood rheology, including haemoglobin mass, blood and plasma volume and blood viscosity, cardiac output, blood pressure and changes in total and local vascular resistances through pharmacological dissection of α-adrenergic signalling pathways within non-active and active skeletal muscle. At rest, Andeans with chronic mountain sickness had a substantial plasma volume contraction, which alongside a higher red blood cell volume, caused an increase in blood viscosity yet similar total blood volume. Moreover, both morphological and functional alterations in the periphery normalized vascular shear stress and blood pressure despite high sympathetic nerve activity. During exercise, blood pressure, cardiac work and global oxygen delivery increased similar to healthy Andeans but were sustained by modifications in both non-active and active skeletal muscle vascular function. These findings highlight widespread physiological adaptations that can occur in response to polycythaemia, which allow the maintenance of exercise capacity.

A novel metric linking stellate ganglion neuronal population dynamics to cardiopulmonary physiology

Cardiopulmonary sympathetic control is exerted via stellate ganglia (SG); however, little is known about how neuronal firing patterns in the stellate ganglion relate to dynamic physiological function in the heart and lungs. We performed continuous extracellular recordings from SG neurons using multielectrode arrays in chloralose-anesthetized pigs (n = 6) for 8-9 h. Respiratory and left ventricular pressures (RP and LVP, respectively) and the electrocardiogram (ECG) were recorded concomitantly. Linkages between sampled spikes and LVP or RP were determined using a novel metric to evaluate specificity in neural activity for phases of the cardiac and pulmonary cycles during resting conditions and under various cardiopulmonary stressors. Firing frequency (mean 4.6 ± 1.2 Hz) varied spatially across the stellate ganglion, suggesting regional processing. The firing pattern of most neurons was synchronized with both cardiac (LVP) and pulmonary (RP) activity indicative of cardiopulmonary integration. Using the novel metric to determine cardiac phase specificity of neuronal activity, we found that spike density was highest during diastole and near-peak systole. This specificity was independent of the actual LVP or population firing frequency as revealed by perturbations to the LVP. The observed specificity was weaker for RP. Stellate ganglion neuronal populations exhibit cardiopulmonary integration and profound specificity toward the near-peak systolic phase of the cardiac cycle. This novel approach provides practically deployable tools to probe stellate ganglion function and its relationship to cardiopulmonary pathophysiology.NEW & NOTEWORTHY Activity of stellate ganglion neurons is often linking indirectly to cardiac function. Using novel approaches coupled with extended period of recordings in large animals, we link neuronal population dynamics to mechanical events occurring at near-peak systole. This metric can be deployed to probe stellate ganglion neuronal control of cardiopulmonary function in normal and disease states.

Combination Biomarkers for Risk Stratification in Patients With Chronic Heart Failure Biomarkers Prognostication in HF

BACKGROUND

Current guidelines recommend measuring natriuretic peptide biomarkers to establish prognosis in patients with chronic heart failure with reduced ejection fraction (HFrEF). We assessed whether a combination biomarkers approach improve prognostication in patients with stable HFrEF.

METHODS AND RESULTS

An observational cohort study recruited 202 patients with stable HFrEF at a single center, tertiary care hospital undergoing elective cardiac resynchronization therapy device placement from 2013 to 2015. Twenty-four biomarkers were analyzed individually and in combination using Cox proportion hazard regression model for major adverse cardiac events (ie, death, cardiac transplant, left ventricular assist device placement), and major adverse cardiac events plus HF hospitalizations. The single best biomarker for predicting major adverse cardiac events is peripheral mid-regional pro-adrenomedullin (C statistic = 0.771 ± 0.045) compared to current guideline recommended N-terminal pro b-type natriuretic peptide (C=0.668 ± 0.046). The best combined biomarkers for predicting major adverse cardiac events are blood urea nitrogen, coronary sinus C-reactive protein, peripheral mid-regional pro-atrial natriuretic peptide and peripheral soluble IL-1 receptor-like 1 (C = 0.767 ± 0.036).

CONCLUSIONS

In this observational cohort, the combined biomarkers (blood urea nitrogen, C-reactive protein, mid-regional pro-atrial natriuretic peptide and soluble IL-1 receptor-like 1) or the single biomarker (mid-regional pro-adrenomedullin) was superior to N-terminal pro B-type natriuretic peptide, the current guideline recommended biomarker in predicting cardiovascular outcomes in patients with HFrEF. Larger studies are needed to validate these findings and examine whether single or combined biomarkers improve HFrEF prognostication.

Innervation and Neuronal Control of the Mammalian Sinoatrial Node a Comprehensive Atlas

[Figure: see text].

Why Do We Not Assess Sympathetic Nervous System Activity in Heart Failure Management: Might GRK2 Serve as a New Biomarker?

Heart failure (HF) represents the end-stage condition of several structural and functional cardiovascular diseases, characterized by reduced myocardial pump function and increased pressure load. The dysregulation of neurohormonal systems, especially the hyperactivity of the cardiac adrenergic nervous system (ANS), constitutes a hallmark of HF and exerts a pivotal role in its progression. Indeed, it negatively affects patients’ prognosis, being associated with high morbidity and mortality rates, with a tremendous burden on global healthcare systems. To date, all the techniques proposed to assess the cardiac sympathetic nervous system are burdened by intrinsic limits that hinder their implementation in clinical practice. Several biomarkers related to ANS activity, which may potentially support the clinical management of such a complex syndrome, are slow to be implemented in the routine practice for several limitations due to their assessment and clinical impact. Lymphocyte G-protein-coupled Receptor Kinase 2 (GRK2) levels reflect myocardial β-adrenergic receptor function in HF and have been shown to add independent prognostic information related to ANS overdrive. In the present manuscript, we provide an overview of the techniques currently available to evaluate cardiac ANS in HF and future perspectives in this field of relevant scientific and clinical interest.

Neurohumoral, cardiac and inflammatory markers in the evaluation of heart failure severity and progression

Heart failure is common in adult population, accounting for substantial morbidity and mortality worldwide. The main risk factors for heart failure are coronary artery disease, hypertension, obesity, diabetes mellitus, chronic pulmonary diseases, family history of cardiovascular diseases, cardiotoxic therapy. The main factor associated with poor outcome of these patients is constant progression of heart failure. In the current review we present evidence on the role of established and candidate neurohumoral biomarkers for heart failure progression management and diagnostics. A growing number of biomarkers have been proposed as potentially useful in heart failure patients, but not one of them still resembles the characteristics of the “ideal biomarker.” A single marker will hardly perform well for screening, diagnostic, prognostic, and therapeutic management purposes. Moreover, the pathophysiological and clinical significance of biomarkers may depend on the presentation, stage, and severity of the disease. The authors cover main classification of heart failure phenotypes, based on the measurement of left ventricular ejection fraction, including heart failure with preserved ejection fraction, heart failure with reduced ejection fraction, and the recently proposed category heart failure with mid-range ejection fraction. One could envisage specific sets of biomarker with different performances in heart failure progression with different left ventricular ejection fraction especially as concerns prediction of the future course of the disease and of left ventricular adverse/reverse remodeling. This article is intended to provide an overview of basic and additional mechanisms of heart failure progression will contribute to a more comprehensive knowledge of the disease pathogenesis.

Rapid measurement of cardiac neuropeptide dynamics by capacitive immunoprobe in the porcine heart

Sympathetic control of regional cardiac function occurs through postganglionic innervation from stellate ganglia and thoracic sympathetic chain. Whereas norepinephrine (NE) is their primary neurotransmitter, neuropeptide Y (NPY) is an abundant cardiac cotransmitter. NPY plays a vital role in homeostatic processes including angiogenesis, vasoconstriction, and cardiac remodeling. Elevated sympathetic stress, resulting in increased NE and NPY release, has been implicated in the pathogenesis of several cardiovascular disorders including hypertension, myocardial infarction, heart failure, and arrhythmias, which may result in sudden cardiac death. Current methods for the detection of NPY in myocardium are limited in their spatial and temporal resolution and take days to weeks to provide results [e.g., interstitial microdialysis with subsequent analysis by enzyme-linked immunosorbent assay (ELISA), high performance liquid chromatography (HPLC), or mass spectrometry]. In this study, we report a novel approach for measurement of interstitial and intravascular NPY using a minimally invasive capacitive immunoprobe (C.I. probe). The first high-spatial and temporal resolution, multichannel measurements of NPY release in vivo are provided in both myocardium and transcardiac vascular space in a beating porcine heart. We provide NPY responses evoked by sympathetic stimulation and ectopic ventricular pacing and compare these to NE release and hemodynamic responses. We extend this approach to measure both NPY and vasoactive intestinal peptide (VIP) and show differential release profiles under sympathetic stimulation. Our data demonstrate rapid and local changes in neurotransmitter profiles in response to sympathetic cardiac stressors. Future implementations include real-time intraoperative determination of cardiac neuropeptides and deployment as a minimally invasive catheter.NEW & NOTEWORTHY The sympathetic nervous system regulates cardiac function through release of neurotransmitters and neuropeptides within the myocardium. Neuropeptide Y (NPY) acts as an acute cardiac vasoconstrictor and chronically to regulate angiogenesis and cardiac remodeling. Current methodologies for the measure of NPY are not capable of providing rapid readouts on a single-sample basis. Here we provide the first in vivo methodology to report dynamic, localized NPY levels within both myocardium and vascular compartments in a beating heart.

Autonomic Modulation for Cardiovascular Disease

Dysfunction of the autonomic nervous system has been implicated in the pathogenesis of cardiovascular disease, including congestive heart failure and cardiac arrhythmias. Despite advances in the medical and surgical management of these entities, progression of disease persists as does the risk for sudden cardiac death. With improved knowledge of the dynamic relationships between the nervous system and heart, neuromodulatory techniques such as cardiac sympathetic denervation and vagal nerve stimulation (VNS) have emerged as possible therapeutic approaches for the management of these disorders. In this review, we present the structure and function of the cardiac nervous system and the remodeling that occurs in disease states, emphasizing the concept of increased sympathoexcitation and reduced parasympathetic tone. We review preclinical evidence for vagal nerve stimulation, and early results of clinical trials in the setting of congestive heart failure. Vagal nerve stimulation, and other neuromodulatory techniques, may improve the management of cardiovascular disorders, and warrant further study.

Sympathetic nervous system activation and heart failure: Current state of evidence and the pathophysiology in the light of novel biomarkers

Heart failure (HF) is a complex clinical syndrome characterized by the activation of at least several neurohumoral pathways that have a common role in maintaining cardiac output and adequate perfusion pressure of target organs and tissues. The sympathetic nervous system (SNS) is upregulated in HF as evident in dysfunctional baroreceptor and chemoreceptor reflexes, circulating and neuronal catecholamine spillover, attenuated parasympathetic response, and augmented sympathetic outflow to the heart, kidneys and skeletal muscles. When these sympathoexcitatory effects on the cardiovascular system are sustained chronically they initiate the vicious circle of HF progression and become associated with cardiomyocyte apoptosis, maladaptive ventricular and vascular remodeling, arrhythmogenesis, and poor prognosis in patients with HF. These detrimental effects of SNS activity on outcomes in HF warrant adequate diagnostic and treatment modalities. Therefore, this review summarizes basic physiological concepts about the interaction of SNS with the cardiovascular system and highlights key pathophysiological mechanisms of SNS derangement in HF. Finally, special emphasis in this review is placed on the integrative and up-to-date overview of diagnostic modalities such as SNS imaging methods and novel laboratory biomarkers that could aid in the assessment of the degree of SNS activation and provide reliable prognostic information among patients with HF.

The cardiac sympathetic co-transmitter neuropeptide Y is pro-arrhythmic following ST-elevation myocardial infarction despite beta-blockade

AIMS

ST-elevation myocardial infarction is associated with high levels of cardiac sympathetic drive and release of the co-transmitter neuropeptide Y (NPY). We hypothesized that despite beta-blockade, NPY promotes arrhythmogenesis via ventricular myocyte receptors.

METHODS AND RESULTS

In 78 patients treated with primary percutaneous coronary intervention, sustained ventricular tachycardia (VT) or fibrillation (VF) occurred in 6 (7.7%) within 48 h. These patients had significantly (P < 0.05) higher venous NPY levels despite the absence of classical risk factors including late presentation, larger infarct size, and beta-blocker usage. Receiver operating curve identified an NPY threshold of 27.3 pg/mL with a sensitivity of 0.83 and a specificity of 0.71. RT-qPCR demonstrated the presence of NPY mRNA in both human and rat stellate ganglia. In the isolated Langendorff perfused rat heart, prolonged (10 Hz, 2 min) stimulation of the stellate ganglia caused significant NPY release. Despite maximal beta-blockade with metoprolol (10 μmol/L), optical mapping of ventricular voltage and calcium (using RH237 and Rhod2) demonstrated an increase in magnitude and shortening in duration of the calcium transient and a significant lowering of ventricular fibrillation threshold. These effects were prevented by the Y1 receptor antagonist BIBO3304 (1 μmol/L). Neuropeptide Y (250 nmol/L) significantly increased the incidence of VT/VF (60% vs. 10%) during experimental ST-elevation ischaemia and reperfusion compared to control, and this could also be prevented by BIBO3304.

CONCLUSIONS

The co-transmitter NPY is released during sympathetic stimulation and acts as a novel arrhythmic trigger. Drugs inhibiting the Y1 receptor work synergistically with beta-blockade as a new anti-arrhythmic therapy.

Cardiac sympathetic activation circumvents high-dose beta blocker therapy in part through release of neuropeptide Y

The sympathetic nervous system plays an important role in the occurrence of ventricular tachycardia (VT). Many patients, however, experience VT despite maximal doses of beta blocker therapy, possibly due to the effects of sympathetic cotransmitters such as neuropeptide Y (NPY). The purpose of this study was to determine, in a porcine model, whether propranolol at doses higher than clinically recommended could block ventricular electrophysiological effects of sympathoexcitation via stellate ganglia stimulation, and if any residual effects are mediated by NPY. Greater release of cardiac NPY was observed at higher sympathetic stimulation frequencies (10 and 20 vs. 4 Hz). Despite treatment with even higher doses of propranolol (1.0 mg/kg), electrophysiological effects of sympathetic stimulation remained, with residual shortening of activation recovery interval (ARI), a surrogate of action potential duration (APD). Adjuvant treatment with the NPY Y1 receptor antagonist BIBO 3304, however, reduced these electrophysiological effects while augmenting inotropy. These data demonstrate that high-dose beta blocker therapy is insufficient to block electrophysiological effects of sympathoexcitation, and a portion of these electrical effects in vivo are mediated by NPY. Y1 receptor blockade may represent a promising adjuvant therapy to beta-adrenergic receptor blockade.

Sympathetic Denervation for Treatment of Ventricular Arrhythmias

Ventricular arrhythmias are a major cause of morbidity and mortality in patients with heart disease. A growing understanding of the cardiac autonomic nervous system's crucial role in the pathogenesis of ventricular arrhythmias has led to the development of several neuromodulation therapies. Sympathetic neuromodulation is being increasingly utilized to treat ventricular arrhythmias refractory to medical therapy and catheter ablation. There is a growing body of preclinical and clinical evidence supporting the use of thoracic epidural anesthesia, stellate ganglion blockade, cardiac sympathetic denervation, and renal denervation in the treatment of recurrent ventricular arrhythmias. This review summarizes the relevant literature and discusses approaches to sympathetic neuromodulation, particularly in the management of scar-related ventricular arrhythmias.