Ultrasound-guided stellate ganglion block with lidocaine and dexmedetomidine for refractory electrical storm after acute myocardial infarction: a case report

Technical Summary: Ultrasound-Guided Stellate Ganglion Block with Lidocaine and Dexmedetomidine for Refractory Electrical Storm

Problem Statement
Refractory electrical storm (ES) following acute myocardial infarction (AMI) represents a life-threatening condition characterized by recurrent ventricular tachycardia (VT) or ventricular fibrillation (VF) despite maximal pharmacological therapy, deep sedation, and electrical cardioversion. In such cases, conventional management often fails, leading to high in-hospital mortality. While Stellate Ganglion Block (SGB) has emerged as a rescue intervention to reduce cardiac sympathetic tone, the specific utility of combining dexmedetomidine with local anesthetics for ultrasound-guided SGB in the context of refractory ES post-AMI remains underreported.

Methodology
The study presents a single-case report of a 46-year-old female patient admitted with AMI complicated by cardiogenic shock. The patient required veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and intra-aortic balloon pump (IABP) support following percutaneous coronary intervention (PCI). Despite aggressive management including beta-blockade, antiarrhythmics, and deep sedation, the patient experienced recurrent VF refractory to multiple cardioversions.

The intervention involved a two-stage approach using ultrasound-guided left SGB:

1. First Intervention: Performed at the C6 transverse process level using an in-plane technique. 4 mL of 0.75% lidocaine was injected onto the surface of the longus colli muscle, lateral to the common carotid artery.
2. Second Intervention: Performed approximately 48 hours after the recurrence of VF. The same anatomical site was targeted using a mixture of 4 mL of 0.75% lidocaine and 0.5 µg/kg of dexmedetomidine.

The procedure utilized real-time high-frequency ultrasound guidance to ensure accurate needle placement and avoid complications such as hematoma or pneumothorax. The patient was monitored for Horner's syndrome as a marker of successful block, and cardiac rhythm was continuously assessed.

Key Results

• First Block: The initial administration of lidocaine alone resulted in the development of Horner's syndrome (increased temperature and mild flushing of the left face) and a marked reduction in VF frequency. However, the arrhythmia recurred approximately 48 hours later.
• Second Block: Following the administration of the lidocaine-dexmedetomidine mixture, VF ceased entirely. The patient experienced only occasional premature ventricular contractions and self-terminating short runs of ventricular tachycardia.
• Clinical Outcome: Following the stabilization of the cardiac rhythm, the patient's cardiac function improved. She was successfully weaned from VA-ECMO one week later, extubated, and discharged home after one month with full recovery. No procedural complications (e.g., hematoma, nerve palsy) were observed.

Key Contributions

• Adjuvant Efficacy: The case demonstrates that adding dexmedetomidine to lidocaine for SGB may provide more durable antiarrhythmic efficacy compared to lidocaine alone in refractory ES. The first block provided temporary relief, while the second block with the adjuvant resulted in sustained suppression of the storm.
• Safety in Critical Care: The report confirms the feasibility and safety of performing ultrasound-guided SGB in patients on VA-ECMO with ongoing anticoagulation, provided precise in-plane needle guidance is used.
• Bridge to Recovery: The intervention served as a critical bridge, interrupting the cycle of "sympathetic storm–myocardial ischemia–hemodynamic deterioration," thereby allowing time for myocardial repair and successful weaning from mechanical circulatory support.

Significance and Claims
The authors posit that this case offers a fresh perspective on anti-sympathetic treatment in cardiac critical care. They claim that the combination of lidocaine and dexmedetomidine for SGB may extend the duration of sympathetic blockade, offering a potential solution for patients who fail conventional therapies. However, the paper maintains a modest stance, acknowledging that while the staged response suggests a synergistic effect, larger prospective studies are required to confirm the safety and effectiveness of this specific formulation. The authors emphasize that this approach provides a critical time window for myocardial repair in extreme critical illness, positioning SGB not just as a bridge to surgical sympathectomy, but potentially to autonomous cardiac recovery.