Introduction:
Chronic durable lesions after radiofrequency ablation (RFA) of myocardial tissue remain difficult to achieve. Tissue exposed to RFA will often recover electrical activity despite initial dormancy. Heat sensitive liposomes (HSL) carrying doxorubicin has been shown to enhance RF destruction of tumors.
Hypothesis:
We sought to evaluate whether HSL doxorubicin will improve myocardial RFA lesion durability.
Methods:
Using an in vivo porcine model, 3 linear RF ablations per animal were performed by blinded operators in the right atrium after systemic HSL doxorubicin infusion or saline control: posterior (20W), septal (30W), and lateral (40W). Each line was created under standardized 3D mapping settings with inter-lesion distances of 4-6 mm to intentionally simulate linear RF gaps. Voltage mapping was performed immediately after ablation (Day 0) and after 2 weeks of survival. Comparisons were made in linear low voltage areas (LVA) from Day 0 to 2 weeks. Pathological staining of porcine RA ablation was also performed to assess for histological linear gaps.
Results:
There was no immediate difference in Day 0 LVA < 0.5 mV after ablation for HSL and controls. However, a significant increase in LVA < 0.5 mV was observed at 2 weeks in HSL animals (figure) with lesion progression in 3/5, compared to 0/4 controls, p< 0.05. There were fewer gaps identified with voltage remapping and on histology for HSL subjects compared to controls.
Conclusions:
RFA with concurrent HSL doxorubicin will be more durable and result in lesion progression with fewer linear gaps over time. Further confirmatory studies are needed.
Ex-Vivo and In-Vivo Studies in a Porcine Model for Experimental Validation of an Embedded System Designed for Radiofrequency Ablation of Hepatocellular Carcinoma