Bioinspired balloon catheter integrated with stretchable “flounder” electrodes under high voltage for uniform pulsed field ablation

Figures

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  Fig. 1.. Design concept of balloon electrode of PFA for AF treatment. (A) Schematic illustration of catheter ablation for AF treatment. The system consists of an interventional multielectrode catheter and a pulse generator; during the procedure, a catheter is inserted through the femoral artery and advanced into the atrium; electrodes from the catheter target regions with abnormal electrical activity in the pulmonary veins, aiming to restore normal heart rhythm. (B) The comparison of ablation principle and distal morphology of RF, cryoablation, and PFA. Thermal ablation of RF (blue box) and cryoablation (green box) damages all tissue types indiscriminately, while PFA was shown to preferential ablation with tissue selectivity. Electrode catheters come in various shapes—focal, circular, spline, basket, and balloon—which influence outcomes by ablated uniformity. (C) Design principle of the electrodes inspired by the skeleton of deep-sea flounder and peeling of citrus fruits. (D) Schematic illustration of the freely inflated/deflated balloon catheter intervened in the atrium.

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  Fig. 2.. Mechanics and electric field simulations of balloon-based electrodes. (A) Simulation results for the deflation process of the balloon electrode showing the distribution of maximum principal tresses at the electrodes. (B to D) Simulation results for the distribution of electric fields excited by the balloon electrode. (B) The top view of electric field area excited by balloon electrodes with different numbers of electrodes and exciting voltages [the boundary is 400 V/cm; black dashed box indicated configurations with a minimum depth of electric field greater than 2 mm; the different colors of wireframes correspond to the examples in [(C), right] and in (D). (C) The depth of electric field at different circular positions of the balloon with an electric field of 400 V/cm [left: 6 (yellow dashed-dotted line)/8 (green dashed line)/10 (red solid line)/12 (blue dotted line) electrodes with a voltage of 1000 V; middle: 10 electrodes with voltages of 500 V (yellow dashed-dotted line), 1000 V (red solid line), and 1500 V (blue dotted line); right: depths of more than 2 mm (green dashed line: 8 electrodes with voltages of 1500 V labeled “8–1500 V”; red solid line: “10–1000 V”; blue dotted…

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  Fig. 3.. Fabrication and bionic integration process of the e-balloon. (A) Fabrication process of the electrodes. (B) Bending and twisting tests of electrodes attached to balloon slices with different adhesives (nos.1 to 4). (C) Schematic of the LILY mold for the electrode transfer printing. (D) Biomimetic principle of LILY mold that mimics the diurnal bloom and nocturnal close of water lilies. (E) The process of transfer printing exhibiting two diurnal and two nocturnal states of the LILY mold (from diurnal states 1 and 2 to nocturnal states 1 and 2 and back to diurnal state 1).

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  Fig. 4.. Demonstration of balloon inflation and PFA effect variation on vegetable models. (A) Inflating process of a balloon electrode deployed from a mock catheter. (B to D) PFA effect verification on potatoes. (B) Influencing factors of ablation depth including resting time, voltage, and pulse width. (C) Cross-reference of the voltage, pulse width, and resting time. All potatoes after PFA show circular uniform ablation lesions. (D) The difference of ablation depths between the surface and the section of potatoes after PFA tends to be stable with the increase of voltages and pulse widths.

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  Fig. 5.. In vivo animal experiments. (A) PFA on thigh and cardiac muscles of a rabbit. (B) An attenuation of electrocardiogram (ECG) signal from the rabbit after PFA on cardiac muscle. (C) Histological sections of thigh muscle after PFA from a rabbit (underwent H&E and Masson’s trichrome stains). The dashed line indicates the ablation lesion boundary. (D) The catheter intervened in an adult swine. (E) The self-developed pulse power and a balloon electrode that has completed interventional PFA. (F) Intraoperative real-time imaging with catheter intervention and balloon inflation in the right superior pulmonary vein of a swine. (G) Everted appendage of the pulmonary vein after PFA from a swine. (H) Histological sections of the pulmonary vein after PFA from a swine. The dashed line shows the ablation lesion boundary. a.u., arbitrary units.