Autonomic nervous system control of the heart is a dynamic process in both health and disease. A multilevel neural network is responsible for control of chronotropy, lusitropy, dromotropy, and inotropy. Intrinsic autonomic dysfunction arises from diseases that directly affect the autonomic nerves, such as diabetes mellitus and the syndromes of primary autonomic failure. Extrinsic autonomic dysfunction reflects the changes in autonomic function that are secondarily induced by cardiac or other disease. An array of tests interrogate various aspects of cardiac autonomic control in either resting conditions or with physiological perturbations from resting conditions. The prognostic significance of these assessments have been well established. Clinical usefulness has not been established, and the precise mechanistic link to mortality is less well established. Further efforts are required to develop optimal approaches to delineate cardiac autonomic dysfunction and its adverse effects to develop tools that can be used to guide clinical decision-making.

Background: Patients receive education before implantable cardioverter defibrillator (ICD) implantation. Patients’ understanding of ICD therapy requires investigation. Methods: A retrospective cohort study was carried out at two implant centers where patients are educated during a consenting process pre‐ICD implantation. Questionnaires examining understanding of ICD therapy were completed during telephone interviews of patients with ICDs. Results: Of 75 patients interviewed, 62 (83%) were male. The median age at time of ICD implantation was 64 years (standard deviation [SD] = 9.4; range: 29–82 years). The median interval from implantation to interview was 3 years (SD = 1.9; range: 0.1–9.0 years). Despite 83% (62 of 75) claiming to understand the reason for ICD implantation, no patient suggested arrhythmia termination when describing the indication. Of shock recipients, 60% (12 of 20) felt poorly prepared for shock therapy. Of patients who experienced a device‐related complication, 83% (10 of 12) reported feeling inadequately forewarned of complications. Excluding patients with cardiac resynchronization therapy defibrillators (n = 6), 65% (45 of 69), 52% (36 of 69), 50% (35 of 69), and 61% (42 of 69) believe their ICD reduces risk of heart attack and improves breathing, exercise capacity, and heart function, respectively. Ninety‐three percent (70 of 75) are satisfied with their decision to accept ICD therapy. Only 12% (9 of 75) believe they will want to inactivate therapies in setting of terminal illness. Conclusions: Despite preimplantation education, patient comprehension of the risks and benefits of ICD therapy is poor. Patients’ expectations of ICD therapy may be inappropriate. Education strategies before and after implantation require improvement. (PACE 2012; 35:1097–1102)

Autonomic Regulation Therapy (ART) is a rapidly emerging therapy in the management of congestive heart failure secondary to systolic dysfunction. Modulation of the cardiac neuronal hierarchy can be achieved with bioelectronics modulation of the spinal cord, cervical vagus, baroreceptor, or renal nerve ablation. This review will discuss relevant preclinical and clinical research in ART for systolic heart failure. Understanding mechanistically what is being stimulated within the autonomic nervous system by such device-based therapy and how the system reacts to such stimuli is essential for optimizing stimulation parameters and for the future development of effective ART.

Background Selective, bilateral cervicothoracic sympathectomy has proven to be effective for managing ventricular arrhythmias in the setting of structural heart disease. The procedure currently employed removes the caudal portions of both stellate ganglia, along with thoracic chain ganglia down to T4 ganglia. Objective To define the relative contributions of T1-T2 and the T3-T4 paravertebral ganglia in modulating ventricular electrical function. Methods In anesthetized vagotomised porcine subjects (n=8), the heart was exposed via sternotomy along with right and left paravertebral sympathetic ganglia to the T4 level. A 56-electrode epicardial sock was placed over both ventricles to assess epicardial activation recovery intervals (ARI) in response to individually stimulating right and left stellate vs T3 paravertebral ganglia. Responses to T3 stimuli were repeated following surgical removal of the caudal portions of stellate ganglia and T2 bilaterally. Results In intact preparations, stellate ganglion vs T3 stimuli (4Hz, 4ms duration) were titrated to produce equivalent decreases in global ventricular ARIs (right-side 85±6 vs 55±10 ms; left-side 24±3 vs 17±7 ms). Threshold of stimulus intensity applied to T3 ganglia to achieve threshold was 3 times that of T1 threshold. ARIs in unstimulated states were unaffected by bilateral stellate-T2 ganglion removal. Following acute decentralization, T3 stimulation failed to change ARIs. Conclusion Preganglionic sympathetic efferents arising from the T1-T4 spinal cord that project to the heart transit through stellate ganglia via the paravertebral chain. T1-T2 surgical excision is thus sufficient to functionally interrupt central control of peripheral sympathetic efferent activity.

Anaemia was relatively common in patients attending for routine outpatient diabetes clinic review. The high prevalence of anaemia supports the routine screening for anaemia in the diabetes out-patient clinic, including in those without overt nephropathy.

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Awareness of cardiovascular risk and knowledge of effective measures to reduce this were low in our study and an alternative means of education may need to be considered.

Introduction Neuromodulation of the paravertebral ganglia, using symmetric voltage controlled kilohertz frequency alternating current (KHFAC), has the potential to be a reversible alternative to surgical intervention in patients with refractory ventricular arrhythmias. KHFAC creates scalable focal inhibition of action potential conduction. Objective To evaluate the efficacy of KHFAC, when applied to T1–T2 paravertebral chain, to mitigate sympathetic outflow to the heart. Methods In anesthetized, vagotomized, porcine subjects the heart was exposed via midline sternotomy along with paravertebral chain ganglia. The T3 paravertebral ganglion was electrically stimulated and activation recovery intervals (ARI) were obtained from a 56-electrode sock placed over both ventricles. A bipolar Ag electrode was wrapped around the paravertebral chain between T1 and T2 and connected to a symmetric, voltage controlled KHFAC generator. Comparison of cardiac indices during T3 stimulation conditions, with and without KHFAC, provided a measure of block efficacy. Results Right-sided T3 stimulation (4Hz) was titrated to produce reproducible ARI changes from baseline (52±30ms). KHFAC resulted in a 67% mitigation of T3 electrical stimulation effects on ARI (18.5±22ms, p<0.005). T3 stimulation repeated after KHFAC produced equivalent ARI changes as control. KHFAC evoked a transient functional sympatho-excitation at onset that was inversely related to frequency and directly related to intensity. Optimum block threshold was 15 kHz and 15 volts. Conclusions KHFAC applied to nexus (convergence) points of the cardiac nervous system produce a graded and reversible block of underlying axons. As such, KHFAC has the therapeutic potential for on-demand and reversible mitigation of sympatho-excitation.