Finite-Element Analysis of Temperature Rise and Lesion Formation from Catheter Ultrasound Ablation Transducers

Abstract—A model using finite-element analysis (FEA) has been developed to calculate the temperature rise in tis-sue from intracardiac ultrasound ablation catheters and to predict if this temperature rise is adequate for producing a lesion in the tissue. In the model, acoustic fields are sim-ulated with Field II, and heat transfer is modeled with an FEA program. To validate the model, we compare its results to experimental results from an integrated, real-time three-dimensional (3-D) ultrasound imaging and ultrasound abla-tion catheter. The ultrasound ablation transducer is a ring transmitting at 10 MHz capable of producing an acoustic intensity of 16 W/cm2. It was used to ablate four lesions in tissue, and temperature rise as a function of time was monitored by embedded thermocouples. The average ab-solute difference between final temperatures predicted by FEA and those measured is 1.95 0.72C. Additionally, model and experimental lesion size are in good agreement. The model then is used to design a new ultrasound catheter with a 7.5 MHz linear phased array for ablation. Eight de-signs are modeled, and acoustic intensity, temperature rise, and ablation ability are compared. I