Treating cardiac disease with catheter-based tissue heating

Two applications of microwave internal biological heating are discussed. Both microwave assisted balloon angioplasty (MABA) and microwave cardiac ablation (MCA) consist of an antenna applicator fed by means of coaxial cable, which passes through a catheter. The antenna designs take advantage of polarization and phase effects of microwaves to create specific power deposition patterns. MABA with a helix and mode filter balloon uses the large differences in the dielectric characteristics of high water content (HWC) and low water content (LWC) tissue to preferentially heat and weld plaque while sparing healthy artery walls. Wide aperture MCA uses an unfurlable spiral antenna within a balloon to generate a deep large ablation volume in diseased cardiac tissue. Theoretical studies have been validated with a variety of in-vitro and in-vivo experiments. There is less of a potential for tissue-surface charring with microwaves than with RF ablation. Live animal studies indicate that MCA is well tolerated by animals.