JMT Medical is a medical device company focused on collaborative solutions to relieve obstructions caused by gallstones. Our mission is to create new methodology designed for greater efficiency, clinical outcomes, economics, and safety.
Founder & CEO, Jeff Rentz, MD, FACS, created JMT Medical to meet the needs of his patients, practice, and medical system. With more than 20 years of surgical experience and through reimagined innovation, devices are being developed to address key clinical problems that surgeons and patients encounter worldwide.
Why I Built This
Surgery first for complications of gallstones is achievable with the right tools. Safely relieving the obstruction is our goal. Many cases are better addressed in the first few days after the onset of symptoms. Good surgeons are reluctant to take someone to the operating room unless they are confident that their problem can be solved. Current techniques require expensive equipment, multiple steps and take a long time compared to my methodology. While visualization of the biliary tree may be necessary in select cases, stenting past the stones or extracting them with fluoroscopic guidance is much simpler, faster, affordable and less time consuming.
I have been using tools for decades that are effective but incompatible and not intuitive. I have developed a suite of tools and streamlined a method of care that will make management readily available for every surgeon in every hospital. It conveniently eliminates delays and expensive patient transfers. Stenting the bile duct safely facilitates a subsequent scheduled, elective ERCP. Forthcoming tools will improve stone removal by gastroenterologists and surgeons.
I have 20 years of experience with the technique and am proud to introduce tools to allow my colleagues around the world to safely and affordably care for their patients.
Company Timeline
2026
Summer - Preparation for FDA Submission
March - Prototypes complete, preparing for FDA submission
2025
October - Dr. Jeff Rentz, JMT Medical Founder, and St. Vincent Regional Hospital receive the 2025 Innovation in Healthcare Award by the Montana Hospital Association for our groundbreaking Robotics Hub Project
September - Stent Patent granted
July - Device Patents published
May - Round 1 funding cycle successfully completed
April - Method Patent published
2024
September - Nonprovisional Patents filed
July - JMT Medical Inc. created
2023
September - Provisional Patents filed
June - JMT Medical LLC founded
Our Team
Leadership & Staff
Jeff Rentz, MD, FACS - Founder
Jeff founded JMT Medical to expand his passion and commitment to providing innovative and efficient care to patients. While practicing in Billings, Montana, Jeff developed procedures that are proven to improve a patient’s healing journey.
Mladenka Dominikovic - Regulatory & Quality
Mladenka oversees the critical functions of manufacturing operations, regulatory compliance and quality. She brings two decades of expertise in the medical device and biomedical industries. Mladenka has played an instrumental leadership role in guiding multiple companies from early-stage startups to acquisition.
Aaron Castillo - Engineering & Project Management
Aaron brings over 20 years of experience in R&D, product development, manufacturing, and commercialization across the medical device, aerospace, and defense industries. Throughout his career, Aaron has helped bring innovative technologies from concept to market, including balloon catheter systems and radiation therapy applicators at Xoft, the POGO Automatic® blood glucose monitoring system at Intuity Medical, and advanced battery systems for biomedical and aerospace applications at EnerSys. His expertise spans mechanical and electromechanical design, manufacturing, design verification and validation, risk management, and FDA and ISO 13485 quality systems.
Missy Rentz - Branding & Communications
Missy brings more than 25 years of marketing experience to the team. Her passion is to find innovative ways to connect with an audience. Missy’s versatile experience has helped build brands in professional sports, transportation, and non-profit organizations.
Partners
Innova MedTec
Patton Design
Advisors
Martin Fessenmaier, PhD - Umberg-Zipser, LLC
Martin has a Ph.D. in molecular biology/biochemistry and over two decades of experience in domestic and International patent prosecution, working in the fields of biochemistry and molecular biology, medical devices, bioinformatics, organic chemistry, and general mechanical arts.
William Starshak - Goldberg-Kohn, Ltd
Bill brings over 25 years of commercial law experience to the JMT team. In his practice, Bill represents lenders and equity sponsors with credit facilities, mergers and acquisitions and leverage buyouts. He has worked on a variety of debt and equity financings throughout the capital stack. Bill is a renowned expert on international finance transactions and provides JMT with access to a world-wide network of lawyers, consultants and capital providers.
Ross Friedman - Goldberg-Kohn, Ltd
Ross Friedman has over a decade of experience helping startups, emerging companies, private equity firms and family offices navigate complex legal matters, including fundraising and strategic growth. He specializes in equity fundraising as well as mergers and acquisitions, advising clients through every stage of their business journey. Ross combines deep transactional expertise with a practical, approachable style to support companies as they scale and succeed.