Intra-arterial Injection of Lidocaine as a Cell Sensitizer during Irreversible Electroporation

Pulsed field ablation: A promising approach for ventricular tachycardia ablation

Radiofrequency ablation (RFA) has been a central therapeutic strategy for ventricular tachycardia (VT). However, concerns about its long-term effectiveness and complications have arisen. Pulsed field ablation (PFA), characterized by its nonthermal, highly tissue-selective ablation technique, has emerged as a promising alternative. This comprehensive review delves into the potential advantages and opportunities presented by PFA in the realm of VT, drawing insights from both animal experimentation and clinical case studies. PFA shows promise in generating superior lesions within scarred myocardial tissue, and its inherent repetition dependency holds the potential to enhance therapeutic outcomes. Clinical cases underscore the promise of PFA for VT ablation. Despite its promising applications, challenges such as catheter maneuverability and proarrhythmic effects require further investigation. Large-scale, long-term studies are essential to establish the suitability of PFA for VT treatment.

Standardizing lymphangiography and lymphatic interventions: a preclinical in vivo approach with detailed procedural steps

PURPOSE

To present a preclinical in vivo approach for standardization and training of lymphangiography and lymphatic interventions using a pictorial review.

MATERIALS AND METHODS

Different lipiodol- and gadolinium-based lymphangiography and lymphatic interventions were performed in twelve (12) landrace pigs with a mean bodyweight of 34 ± 2 kg using various imaging and guiding modalities, similar to the procedures used in humans. The techniques used were explicitly introduced and illustrated. The potential applications of each technique in preclinical training were also discussed.

RESULTS

By applying visual, ultrasonography, fluoroscopy, CT, cone-beam CT, and/or MRI examination or guidance, a total of eleven techniques were successfully implemented in twelve pigs. The presented techniques include inguinal postoperative lymphatic leakage (PLL) establishment, interstitial dye test, five types of lymphangiography [incl. lipiodol-based translymphatic lymphangiography (TL), lipiodol-based percutaneous intranodal lymphangiography (INL), lipiodol-based laparotomic INL, lipiodol-based interstitial lymphangiography, and interstitial magnetic resonance lymphangiography (MRL)], and four types of percutaneous interventions in the treatment of PLL [incl. thoracic duct embolization (TDE), intranodal embolization (INE), afferent lymphatic vessel sclerotherapy (ALVS), and afferent lymphatic vessel embolization (ALVE)].

CONCLUSION

This study provides a valuable resource for inexperienced interventional radiologists to undergo the preclinical training in lymphangiography and lymphatic interventions using healthy pig models.

Pulsed Field Ablation of Left Ventricular Myocardium in a Swine Infarct Model

BACKGROUND

Pulsed field ablation (PFA) leads to cell death by irreversible electroporation. There are limited data about PFA lesion characteristics in the ventricle, particularly in the presence of myocardial scar.

OBJECTIVES

This study sought to evaluate the lesion characteristics of PFA and radiofrequency energy (RFA) in healthy and infarcted left ventricular (LV) myocardium in swine.

METHODS

Swine (n = 10) underwent either: 1) 120-minute left anterior descending coronary artery balloon occlusion myocardial infarction and survived for 6 to 8 weeks (n = 8); or 2) served as healthy control subjects (n = 2). PFA or RFA was delivered to the LV endocardium in regions of healthy myocardium or scar identified with electroanatomical mapping. Bipolar, biphasic PFA was delivered for 2.5 seconds × 4 applications/site using 2 different catheters: linear quadripolar (FOCAL) or multispline 8-pole catheter (BASKET). Gross and histologic measurements of lesion size were performed.

RESULTS

In the PFA group, 21 lesions were delivered to healthy LV and 20 to areas of scar. Overall, there was no significant difference in lesion depth between catheter groups (FOCAL linear vs BASKET; P = 0.740), whereas lesion width was greater for BASKET (10.6 ± 2.4 mm vs 13.3 ± 3.3 mm; P = 0.007). In myocardial scar, lesion depth was not significantly different between PFA catheters (P = 0.235). However, lesion depth for PFA was greater than for RFA (PFA vs RFA; 6.1 ± 1.7 mm vs 3.8 ± 1.7 mm; P = 0.005).

CONCLUSIONS

PFA allows rapid, safe, and effective ablation of surviving islands of myocardium within and around infarcted LV substrate. This technology holds promise for treating infarct-related ventricular tachycardia in humans.

Combination of irreversible electroporation with sustained release of a synthetic membranolytic polymer for enhanced cancer cell killing

Irreversible electroporation (IRE) is used clinically as a focal therapy to ablate solid tumors. A critical disadvantage of IRE as a monotherapy for cancer is the inability of ablating large tumors, because the electric field strength required is often too high to be safe. Previous reports indicate that cells exposed to certain cationic small molecules and surfactants are more vulnerable to IRE at lower electric field strengths. However, low-molecular-weight IRE sensitizers may suffer from suboptimal bioavailability due to poor stability and a lack of control over spatiotemporal accumulation in the tumor tissue. Here, we show that a synthetic membranolytic polymer, poly(6-aminohexyl methacrylate) (PAHM), synergizes with IRE to achieve enhanced cancer cell killing. The enhanced efficacy of the combination therapy is attributed to PAHM-mediated sensitization of cancer cells to IRE and to the direct cell killing by PAHM through membrane lysis. We further demonstrate sustained release of PAHM from embolic beads over 1 week in physiological medium. Taken together, combining IRE and a synthetic macromolecular sensitizer with intrinsic membranolytic activity and sustained bioavailability may present new therapeutic opportunities for a wide range of solid tumors.