Key result
A serpentine 3ω microthermal sensor integrated onto a flexible balloon successfully identified tissue contact versus fluid, distinguished tissue thickness (0.5-2 mm), and measured freezing phase changes.
Why the study?
Pulmonary vein cryoablation for atrial fibrillation lacks methods to assess probe contact, tissue thickness, and freeze completion, as clinical imaging lacks the necessary resolution.
A novel serpentine 3ω microthermal sensor integrated onto a cryoablation balloon can successfully monitor tissue contact, thickness, and freezing phase changes in preclinical testing.
Answers are grounded in this paper and cite their sources.
Supports preclinical development of sensor-guided cryoablation; leaves open human validation and outcome impact.
Treatment of atrial fibrillation by cryoablation of the pulmonary vein (PV) suffers from an inability to assess probe contact, tissue thickness, and freeze completion through the wall. Unfortunately, clinical imaging cannot be used for this purpose as these techniques have resolutions similar in scale (∼1 to 2 mm) to PV thickness and therefore are unable to resolve changes within the PV during treatment. Here, a microthermal sensor based on the "3ω" technique which has been used for thin biological systems is proposed as a potential solution and tested for a cryoablation scenario. First, the sensor was modified from a linear format to a serpentine format for integration onto a flexible balloon. Next, using numerical analyses, the ability of the modified sensor on a flat substrate was studied to differentiate measurements in limiting cases of ice, water, and fat. These numerical results were then complemented by experimentation by micropatterning the serpentine sensor onto a flat substrate and onto a flexible balloon. In both formats (flat and balloon), the serpentine sensor was experimentally shown to: (1) identify tissue contact versus fluid, (2) distinguish tissue thickness in the 0.5 to 2 mm range, and (3) measure the initiation and completion of freezing as previously reported for a linear sensor. This study demonstrates proof of principle that a serpentine 3ω sensor on a balloon can monitor tissue contact, thickness, and phase change which is relevant to cryo and other focal thermal treatments of PV to treat atrial fibrillation.
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Natesan et al. (2020) studied Atrial fibrillation. Serpentine microthermal sensor based on the 3ω technique was evaluated on Ability to monitor tissue contact, thickness, and phase change. A serpentine 3ω microthermal sensor integrated onto a flexible balloon successfully identified tissue contact versus fluid, distinguished tissue thickness (0.5-2 mm), and measured freezing phase changes.
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