Let's talk about the types of aortic valves for heart valve replacement that you use. There are stented versus stentless aortic valves. Dr. Anton Titov, MD. You have a particular interest in determination of the best type of prosthetic heart valve for individual patients. You have studied the performance of stented versus stentless aortic valves in aortic valve replacement surgery. How do these types of heart valves differ from each other? Dr. Anton Titov, MD. How do you decide which patient should get which type of aortic valve for replacement? Dr. Jürgen Ennker, MD. I use a stentless valve predominately in more than 98% of patients. I only use a stented valve in patients who have to receive mitral valves. Because then the aortic annulus is distorted by the mitral valve. This results in the insufficiency of the stentless heart valve. In all other cases, I use stentless heart valves. Because you don't have the stent in the heart valve. This leads to the fact that you can implant a stentless valve. Dr. Jürgen Ennker, MD. This valve is one to two sizes larger than a typical stented valve. This would fit into this specific patient's aortic annulus. These stentless valves were created by nature. It's the pig aortic root. This was produced by the evolution. Millions of years of evolution created this valve. Stented aortic valves are created by man over the last 40 or 50 years. So, I've made up my mind. I think evolution is smarter than we are within 30 or 40 years. The followup with the patient and the feedback I receive from my patients and from my cardiologists support this view. Dr. Jürgen Ennker, MD. Patients come exactly for this scentless aortic valve. Because they have an enlarged aortic annulus. They have a decreased transvalvular gradient. We also have a smaller percentage of patient-prosthesis mismatch. We can eliminate aortic root aneurysms by implanting freestyle valve as a full root. Dr. Anton Titov, MD. This is a big advantage for the patient.