Combined IVUS/FFR microcatheter for guiding complex percutaneous coronary interventions

About This Grant

More than a million percutaneous coronary interventions (PCIs) are performed in the US alone every year. X- ray angiography has been the main guidance technique for PCIs as well as post-PCI evaluation of procedural success. However, physiological assessments show that 24% of patients had residual ischemia with low FFR (fractional flow reserve) values after angiographically successful PCI. Studies showed that increased post-PCI FFR improves event free survival of these patients. Post-PCI FFR can be increased by additional stenting or postdilatation with IVUS image guidance which addresses the anatomical complexity of these cases. By streamlining post-PCI optimization using a single device, a combined IVUS/FFR microcatheter will reduce potential risks and disadvantages in terms of procedural time, radiation dose, contrast usage as well as cost while improving clinical outcomes. To enable FFR measurements and IVUS imaging on the same device, a significantly smaller catheter is needed. This project aims to develop and demonstrate a 2.5F combined coronary IVUS/FFR microcatheter. Specifically, an FFR sensor will be integrated with CMUT-on-CMOS based 40MHz IVUS imaging system on silicon chips. The FFR sensor will be fabricated using the same MEMS fabrication process as the IVUS array and will add minimal complexity to the integrated electronics. Eight of these chips will be used to form a 96 element IVUS array and a flexible transmit beamforming scheme will be implemented to have the required image quality. In addition to improving IVUS use and reach in the coronaries, a side port for guidewire exit at the catheter tip is included for close image guidance of wire manipulation during CTO procedures. This project brings clinicians and engineers with unique capabilities to design and implement the IVUS/FFR microcatheter system and systematically evaluate it from benchtop to animal studies. While the IVUS/FFR chip components - CMUT arrays and application specific integrated circuits (ASICs) - are designed and fabricated, the microcatheter structure will be developed and tested for its mechanical performance and a custom real-time imaging and FFR sensor data acquisition system will be developed. In addition to extensive benchtop testing, IVUS/FFR microcatheter prototypes and system will be tested on perfused diseased human cadaver specimens to optimize process and system parameters. Finally, experiments on swine will be used to evaluate imaging, wire manipulation and pressure measurement performance in comparison to existing IVUS imaging catheters and FFR sensors in a realistic setting. While evidence of improved clinical outcomes is beyond the scope of this project, it is likely that the proposed microcatheter with IVUS and FFR capability will fundamentally enable more effective, more efficient, and safer percutaneous coronary interventions.