Abstract / Summary
BACKGROUND: Radiofrequency catheter ablation (RFCA) uses rigid metallic electrodes whose fixed geometry limits tissue contact, lesion continuity, and safe energy delivery near vulnerable structures. We evaluated a moldable, tissue-conforming conductive hydrogel as an RFCA electrode ex vivo. METHODS: Poly(ether urethane diacrylamide) hydrogels with saline-tuned conductivity were molded into plugs, disks, and bars and affixed to an irrigated 8-Fr catheter. Ablations were performed on excised porcine tissue in circulated saline at 37 C under fixed contact force and irrigation. Lesion geometry, intramural temperatures, and steam pops were compared with bare-metal (BM) electrodes and size-matched metallic analogs; an atrioesophageal stack model assessed collateral injury. Lesions were delineated using triphenyltetrazolium chloride staining. RESULTS: Hydrogel bars produced wide, ellipsoidal lesions (width 10.51 {+/-} 1.40 versus 8.71 {+/-} 1.65 mm for BM; P=0.031; aspect ratio 1.72); size-matched metal bars produced none. Hydrogel disks produced lesions statistically indistinguishable from BM in depth (4.54 {+/-} 0.90 versus 4.84 {+/-} 0.55 mm) and width (9.47 {+/-} 0.89 versus 11.41 {+/-} 2.39 mm), whereas metal disks produced significantly shallower lesions (2.30 {+/-} 1.70 mm; P=0.015 versus BM). In the atrioesophageal model, hydrogel plugs achieved transmural atrial lesions with a reduced esophageal lumen temperature (56.33 {+/-} 3.80 versus 61.30 {+/-} 5.14 C; P=0.046), total lesion depth (4.03 {+/-} 1.25 versus 7.58 {+/-} 0.78 mm; P<0.001), and esophageal lesion width (3.05 {+/-} 2.35 versus 8.70 {+/-} 2.69 mm; P<0.001) compared with BM. Hydrogel electrodes reduced steam-pop risk (relative risk 0.34; 95% CI 0.13-0.88). Plug characterization confirmed saline-dependent conductivity and attenuated energy delivery, with lower subsurface peak temperatures and shallower lesions than BM. CONCLUSIONS: Moldable, conductivity-tunable hydrogels shape RF lesions and may improve ablation safety, supporting evaluation for contiguous or linear lesion sets and ablation near sensitive structures.