William E. Cohn, M.D., is professor of surgery at Baylor College of Medicine, director of the Center for Technology and Innovation at Texas Heart Institute, co-director of Cullen Cardiovascular Research Lab, and staff cardiac surgeon in the Division of Transplant and Mechanical Circulatory Assist at Texas Heart Institute.
Q | What would you consider to be your most successful innovation?
A | I’ve been fortunate to be involved in several impactful innovations. My four favorites are: 1) one of the first commercially available self-retaining coronary stabilizers for performing off-pump beating heart coronary artery bypass; 2) The SentreHeart LARIAT, a percutaneous system for excluding the left atrial appendage in patients with atrial fibrillation at risk for embolic stroke; 3) The TVA Medical percutaneous system for creating arterio-venous fistulas for hemodialysis access in renal failure patients; and 4) the granddaddy of all innovations, working closely with O. H. “Bud” Frazier on the first continuous flow total artificial heart. The artificial heart work has led to our current collaboration with the BiVACOR team to develop what we feel will ultimately be the first practical mechanical replacement for the failing human heart.
In each of these, I filed patents, created several iterations of prototype, performed extensive animal experiments and participated in first-in-man implementation. For the SentreHeart and TVA Medical projects, I hired a CEO, raised several rounds of venture capital and created the companies.
Q | What spurred this innovation?
A | Each of these innovations was triggered by an unmet clinical need. The LARIAT device and the TVA percutaneous AV fistula technology each arose out of an analysis of suboptimal results achieved by currently available technology and the realization that novel tools could be developed that would provide better results using a less invasive approach.
The artificial heart research was a direct result of Frazier’s four-decade crusade to treat advanced heart failure. Over 400,000 patients die of heart failure each year but only 2000 suitable donor hearts are available for transplantation. Leveraging advances from Frazier’s work, we set out to develop an artificial heart that was small enough to be practical and durable enough that it could provide a permanent solution for patients in need.
Q | What are the unique benefits of that innovation that make it a valuable solution?
A | The development of a practical permanent artificial heart has remained an elusive goal despite six decades of effort and the expenditure of tremendous resources. All previous efforts to date have leveraged a pair of volume displacement pumps that utilized flexible diaphragms with paired inlet and outlet valves and some type of internal actuation mechanism. Generally artificial hearts of this design beat about 80 times each minute, which translates to 115,000 beats each day and 42 million beats each year. No man-made device has ever been able to demonstrate this type of endurance for more than a year or so. In addition, these devices have been prohibitively large.
By integrating rapidly spinning impellers, or more recently a single double-sided impeller, we have been able to dispense with the valves, the large complex internal actuation mechanism, and most importantly, the flexible diaphragms, which should make a continuous flow total artificial heart smaller, simpler and significantly more durable than any previous device. We have implanted various iterations of the continuous flow heart in over 80 calves, many of which have lived for several months with the device and have demonstrated the ability to exercise on a motorized treadmill despite the absence of a heart beat or pulse.
The newest iteration, developed by Daniel Timms and his team in our lab as a continuation of the work conducted by Frazier and me over the last nine years, uses a single magnetically suspended double-sided rotor to provide flow to the body and lungs. Because there are no bearings or other areas of mechanical contact, it should never wear out. It is capable of providing over three times the normal cardiac output, has only one moving part, is smaller than a normal heart and autonomously balances the systemic and pulmonary output over 20 times each second.
Q | What resources were helpful to you when you were first starting out?
A | One of the things I enjoy is finding resources in unexpected places. The first several prototypes of my beating heart coronary stabilizer were fashioned from flattened serving spoons cut with a hacksaw in my garage shop. The LARIAT and TVA Medical prototypes were similarly cobbled together from expired catheters that had been discarded and magnets and other components ordered through the Internet. Even some of the components of the first continuous flow artificial hearts Frazier and I made were constructed of Dacron from the fabric store, reinforced with dry wall tape from Home Depot and Silicone caulk from Walmart.
I have a fairly complete machine shop at my house, but more recently, I find I rely heavily on computer-aided design and rapid prototyping on our lab’s 3-D printer. Rapid prototyping notwithstanding, I maintain a well-stocked larder of expired guide-wires, sheaths, balloon catheters, stents, grafts, staplers, laparoscopic instruments and the like for when the innovative spirit hits me. We are extremely fortunate to have a large group of hard-working, highly motivated scientists, engineers and students to help with the innovative process. We are also fortunate to have one of the most experienced and well-equipped large animal cardiovascular research labs in the country, which, as a resource, is invaluable.
Q | What advice would you give to other aspiring entrepreneurs or innovators?
A | The best advice I can give would be innovators or entrepreneurs is, ‘Drive it like you stole it.’ There has to be a sense of urgency in your mission, and to achieve that you need passion. Passion takes energy to maintain, so surround yourself with brilliant, high-energy, like-minded people who believe in your mission. If you don’t have that, you’re better off selling shoes.
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