Stellate Block in Refractory Ventricular Tachycardia: The Calm After the Storm.

Abstract

The increasing use of implantable defibrillators for sudden death prevention and the recent advances in heart failure therapies have significantly altered the natural history of heart disease. An unfortunate consequence of this is the increasing incidence of refractory tachyarrhythmias. The most serious of ventricular arrhythmias (VA) is the electrical storm, defined as ≥3 episodes of sustained ventricular tachyarrhythmia over a 24-hour period.1 The annual incidence varies from 2% to 10% and is associated with a 2to 8-fold increase in mortality. This is most likely a testament to the severely compromised underlying myocardial substrate than to the electrical storm itself. It is well established that the sympathetic nervous system plays an integral role in initiating and driving electrical storm.2 Pharmacological approaches to sympathetic blockade using β-blockers though effective have several shortcomings. The sympathetic nervous system involves multiple nonadrenergic pathways and neuromodulators which are unaffected by these medications. Additionally, the β2 receptor which is untouched by the conventionally cardio-selective β-blockers appears to play an integral proarrhythmic role as well. These shortcomings are overcome by surgical approaches where the cardiac sympathetic supply in its entirety is decentralized. The earliest attempt at surgical sympathectomy was over a century ago when Jonnesco3 performed a left cardiac sympathetic denervation in a successful attempt to relieve refractory angina in syphilitic aortitis.2 Since that time the field has burgeoned with a number of interventions targeting multiple sites along the sympathetic chain. These range from thoracic epidural/general anesthesia, stellate ganglion blockade, renal artery denervation to surgical stellate ganglion resection. Cardiac sympathetic denervation is undeniably beneficial in certain conditions—however, consensus about where it fits into regular practice remains to be established. Percutaneous stellate ganglion blockade (PC-SGB) is currently the least invasive method available, and its role in management of electrical storm is comprehensively explored in this issue of Heart Rhythm by Tian et al.4 In the largest prospective study of PC-SGB to date, 30 patients presenting with drug-refractory electric storm between 2013 and 2018 were included (58±14 years, 73.3% males, mean left ventricular election fraction, 34±15). Ultrasound guidance was used in the majority of patients with half the study population undergoing a left-sided stellate block, with bilateral blockade in the remainder. An incremental approach was used with an initial left-sided SGB, and progression to bilateral block if recurrence of arrhythmia was noted within 10 minutes. Rise in ipsilateral arm temperature was used as a surrogate for efficacy of block, though the authors themselves indicate that the temperatures were inadequately measured. EDITORIAL