Experimental Studies With a 9 French Forward-Looking Intracardiac Imaging and Ablation Catheter Developed in an NIH Supported Bioengineering Research Partnership Grant Program David J. Sahn, 1Kalyanam Shivkumar, 1Aman Majahan, Muhammad Ashraf, Long Liu, 2Jonathan Cannata, 3Xunchang Chen, 4Raymond Chia, 5Aaron Dentinger, 6Matthew O'Donnell, 2K. Kirk Shung, 7Douglas N. Stephens, 5Kai Thomenius Oregon Health & Science University, Portland, OR; 1University of California, Los Angeles, CA; 2University of Southern California, Los Angeles, CA; 3University of Michigan, Ann Arbor, MI; 4Irvine Biomedical, Inc., Irvine, CA; 5GE Global Research, Schenectady, NY; 6University of Washington, Seattle, WA; 7University of California, Davis, CA

Funded by NHLBI Bioengineering Research Partnership grant R01 HL67647 Disclosures No relationships to disclose: Kalyanam Shivkumar; Aman Majahan; Muhammad Ashraf; Long Liu; Jonathan Cannata; Xunchang Chen; Matthew O’Donnell; K. Kirk Shung; Douglas N. Stephens Employed by Irvine Biomedical, Inc.: Raymond Chia Employed by GE Global Research: Aaron Dentinger; Kai Thomenius Occasional consultant to IBI & GE: David J. Sahn Funded by NHLBI Bioengineering Research Partnership grant R01 HL67647

Background electromagnetic localization Transcatheter treatment of arrhythmias by ablation has been targeted in more complex procedures in recent years Fluoroscopy was the major alternative imaging method To shorten long procedures, modern EP employs electromagnetic localization non-contact mapping magnetic catheter manipulation other means of imaging multi-modality integration of 3D anatomy and intracardiac ultrasound

Background Our Bioengineering Research Partnership has proposed and developed new intracardiac imaging and therapy devices for EP ablation and monitoring resynchronization lead placement First device: side-looking catheter very agile 64-element broadband phased array EP recording electrodes has been interfaced with NavX electrofield localization to aid its positioning This paper presents our results with the recently completed forward-looking 9 French catheter device which has a 24-element array on the tip of the catheter, extreme agility

Catheter Used Forward-looking 9 French catheter device 24-element array on the tip of the catheter center frequency of 14 MHz array pitch of 0.065 elements are 1.2 mm in elevation extreme agility Designed for near-field imaging incorporates very high frame rates and ….. Bonding of elements to flex circuit extremely challenging shorting occurred at bend points of original flex circuit longer flex used

Catheter Used Enlarged headshaft Fitted with a second shaft electrode used to provide anchoring ports one to stabilize catheter in front of tissue second port for thermister to verify temperature heating Fitted with a second shaft electrode allows integration of localization with NavX mapping

Methods Ultrasound imaging with single plane fluoroscopy Microlinear probe introduced through both femoral artery and jugular veins Three pigs (40-50 pounds) imaged from right atrium and right ventricle One pig (40-50 pounds) imaged from two locations in right ventricle

Results Ablation could be localized by: tissue character change vaporization bubble formation mechanical changes in behavior of tissue

Discussion First two devices built with piezoelectric ceramic cMUT (computer micromachined ultrasound transducer) version of microlinear array completed cMUTs are wave of the future for intraluminal, intracavitary ultrasound Additional plans for microlinear array extrudable RF ablation electrode adaptation of both ceramic and cMUT versions for HIFU

Conclusion Efforts aimed at providing tools that offer ultrasound guidance using 2D and 3D ultrasound ability to deliver RF HIFU ultrasound energy from the same device providing integrated ability to evaluate changes in mechanical properties, muscle function and tissue temperature Changes in fundamental transducer materials and connectors as well as microflex low profile cabling with slip layers improve steerability, flexibility and decrease the cost of providing intracardiac ultrasound guidance in patients.