Report on CT-Guided Left Stellate Ganglion Cryoneurolysis for Refractory Ventricular Arrhythmias

Academic Background

Ventricular arrhythmias (VAs), including ventricular tachycardia and ventricular fibrillation, pose a significant challenge in cardiovascular medicine due to their high morbidity, mortality, and increasing prevalence. Although current treatments such as antiarrhythmic medications, mechanical circulatory support, and cardiac defibrillation can alleviate the condition to some extent, they often prove ineffective for patients with refractory VAs. Catheter ablation may be beneficial in certain cases, but its effects are typically temporary, and patients must be stable enough to tolerate the procedure. In the context of electrical storm (defined as three or more episodes of sustained or hemodynamically significant VAs within 24 hours), in-hospital mortality remains high, ranging from 29.2% to 53.0%, despite the use of antiarrhythmic drugs and implantable cardioverter-defibrillators.

The sympathetic nervous system plays a critical role in initiating and maintaining VAs, making it a key therapeutic target, especially in patients with electrical storm. β-blockers have been shown to reduce the burden of VAs, but their use is often limited due to hemodynamic concerns. For patients in whom catheter ablation is ineffective or not feasible, surgical sympathetic denervation and stellate ganglion blockade (SGB) can reduce sympathetic tone and thereby decrease the burden of VAs. However, similar to cardiac electrophysiological catheter ablation, surgical sympathectomy may not be feasible in patients with refractory VAs. SGB, performed under ultrasound or CT guidance, provides temporary relief of VAs and is often used as a bridging therapy.

Cryoneurolysis, also known as cryoanalgesia, is an emerging neuromodulation technique that offers advantages over traditional nerve blockade. Cryoneurolysis induces Sunderland grade II axonal injury (axonotmesis) and subsequent Wallerian degeneration, resulting in durable nerve conduction interruption. Importantly, the preservation of connective tissue layers (including the endoneurium, perineurium, and epineurium) facilitates nerve regeneration. Although a single case report has shown that left stellate ganglion cryoneurolysis can provide up to 5 months of VA-free survival, a larger patient cohort and comprehensive safety analysis are essential to evaluate the utility of this technique.

Therefore, this study aimed to assess the safety and efficacy of CT-guided left stellate ganglion cryoneurolysis (SGC) in the treatment of refractory VAs.

Study Source

This study was conducted by Ningcheng Li, Junman Kim, Anshul M. Patel, David W. Markham, Christine M. Tompkins, Youssef Rahban, Glenn Stokken, Matthew Gottbrecht, Frank J. Prologo, and Neil J. Resnick from UMass Memorial Medical Center, Emory University School of Medicine, Piedmont Heart Institute, and the University of Georgia. The study was published in December 2024 in the journal Radiology.

Study Process

Study Subjects and Inclusion Criteria

This retrospective study analyzed patients with refractory VAs who underwent CT-guided left SGC between June 2020 and December 2023 at two tertiary care centers. All patients met the diagnostic criteria for refractory VAs, and no patients were excluded. Data on preprocedural clinical status, procedural approach, procedural outcomes, and adverse events were collected, and the Wilcoxon matched-pairs signed rank test was used to compare the number of defibrillations before and after the procedure.

Procedural Details

The SGC procedure was performed in the CT suite, with patients typically under general anesthesia. Patients were positioned supine with the left upper extremity tucked to the side and the head slightly turned to the right. Helical CT (GE Healthcare) of the neck and upper chest was performed, with contrast media (Omnipaque 350) administered when necessary to evaluate the left stellate ganglion near the T1 costovertebral junction and adjacent anatomical structures. Key structures included the common carotid artery, internal jugular vein, vertebral artery, thyrocervical trunk, costocervical trunk, anterior and middle scalene muscles, longus colli muscle, esophagus, C7, C8, and T1 spinal nerves, brachial plexus, recurrent laryngeal nerve, vagus nerve, and phrenic nerve.

The procedure employed a supraclavicular anterolateral-to-posteromedial approach, with the path lateral to the common carotid artery and internal jugular vein and medial to the anterior scalene muscle. After determining the optimal trajectory, patients were prepared and draped in a sterile fashion, and 3–5 mL of 1% lidocaine was administered for superficial and soft-tissue analgesia. Under intermittent CT fluoroscopic guidance, a single cryoablation probe (IceSphere, Boston Scientific) was carefully advanced to the region of the stellate ganglion. A repeat helical CT image was acquired to confirm the probe position before initiating cryotherapy. A 12–15-minute freeze cycle (typically at 100% power) with a target freeze temperature of −40°C was executed, followed by a 5–10-minute passive thaw process. A second 3–8-minute freeze cycle was performed when the probe tip was near the vertebral artery to mitigate the cold sink effect and ensure sufficient cryoneurolysis.

Clinical Data Collection

Preprocedural and postprocedural clinical information, including baseline characteristics, preprocedural VA management, postprocedural therapy escalation, additional interventions, and patient outcomes, was ascertained by manual review of patient clinical charts. Clinical success was defined as freedom from defibrillation within the preceding 24-hour period.

Study Results

Patient Characteristics

A total of 17 patients (mean age, 60.4 years; 14 male) were included in the study. Seven patients (41%) were receiving β-adrenergic blocking agents, and the mean number of antiarrhythmic medications per patient was 2.2. CT-guided left SGC led to a significant reduction in defibrillations, from a median of 3 (IQR, 3–15) to 0 (IQR, 0–0) in the 24 hours before and after the procedure, respectively (p < .001). Clinical success was achieved in 14 of 17 patients (82%) 24 hours after the procedure and in 15 of 17 patients (88%) 72 hours after the procedure. At a mean follow-up of 469.2 days, 14 of 17 patients (82%) were alive, with no moderate or high-grade adverse events observed. Mild adverse events included left upper extremity neurapraxia (n = 1) and transient Horner syndrome (n = 3).

Conclusion

CT-guided left SGC demonstrated promising effectiveness and safety in treating patients with refractory VAs, warranting consideration for inclusion in a multidisciplinary treatment algorithm for VAs.

Study Highlights

1. Key Findings: CT-guided left SGC significantly reduced the number of defibrillations in patients with refractory VAs, with clinical success rates of 82% at 24 hours and 88% at 72 hours post-procedure.
2. Methodological Innovation: This study is the first large-scale evaluation of CT-guided left SGC in refractory VAs, demonstrating its potential as a novel minimally invasive treatment.
3. Clinical Significance: The study provides a new treatment option for patients with refractory VAs, particularly when traditional therapies are ineffective or not feasible.

Study Value

The scientific value of this study lies in its systematic evaluation of the safety and efficacy of CT-guided left SGC in refractory VAs, offering important insights for future clinical practice. Its clinical application value lies in providing a new treatment option for VA patients, especially in emergency situations such as electrical storm, where SGC can serve as a bridging therapy to buy time for more definitive treatments.

Additional Valuable Information

The limitations of this study include its retrospective design, lack of a control group, and small sample size. Future larger multicenter randomized controlled trials are needed to further validate the efficacy and safety of this technique.