Med-tech entrepreneur Manny Villafaña is on his eighth medical device startup company, Plymouth-based Medical 21. The startup is developing and marketing what it calls the “holy grail” cardiac medical device: an artificial graft for cardiac bypass surgery. Over the past 60 years, many other medical device companies have attempted to make this device without success. In more than a year of trials, Medical 21’s device, the MAVERICS graft, has shown positive results in animals; the next step is clinical trials. Villafaña has the track record—his innovative pacemakers and heart valves launched Cardiac Pacemakers, which was acquired by Boston Scientific; he founded St. Jude Medical, which was sold to Abbott Laboratories; and he developed the new generation ATS heart valve at ATS Medical, now owned by Medtronic.