SBIR Phase I: High Surface Area (HSA) Intraluminal Cryoablation for the Treatment of High-risk Patients with Gallstone Disease

The broader impact of this Small Business Innovation Research (SBIR) Phase I project is to develop a safer alternative to gallbladder surgery for elderly patients at higher risks of complications due to the effects of general anesthesia. Approximately 200,000 Medicare patients undergo surgery to remove their gallbladders every year. Unfortunately, 24% of these patients will experience a perioperative complication due to the effects of general anesthesia, totaling $500 M in cost annually to the US healthcare system. As the population ages and management of chronic disease improves, the need for alternatives to gallbladder surgery increases. This project will develop a process to affect the entire surface of the gallbladder ("ablation"), inducing a healing response that will defunctionalize the gallbladder and obviate the need to remove it. This is the first technology designed to conduct this process within a tube via a minimally invasive approach. Ultimately, this technology could be adapted to create more effective devices for other high surface area tissue targets. The proposed project is a significant improvement over current state-of-practice ablation devices due to its ability to deliver high-surface area ablation within a closed lumen or organ, such as the gallbladder. Existing conductive devices are designed for targeted ablation of discrete lesions rather than therapeutic delivery to large tissue targets, such as the gallbladder. The aim of this project is to develop a new process using open lumen instillation of cryogen to achieve high surface area cryoablation of tissues. This raises several unique engineering challenges, including the design of a delivery mechanism for the uniform distribution of cryogen across a closed lumen and development of a pressure management system to properly evacuate the cryogen gas and prevent an increase in intraluminal pressure. Initial optimization of the cryogen distribution and pressure management system will be conducted using a benchtop thermal load model of the gallbladder to approximate the in vivo thermodynamics. Optimized designs will then be tested in acute and chronic animal models to demonstrate the safety and efficacy of open lumen instillation of cryogen for high surface area intraluminal cryoablation of the gallbladder. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.