Let's start our conversation with aortic valve replacements. Let’s discuss the risks of aortic valve replacement surgical operation. Dr. Anton Titov, MD. You have done thousands of aortic valve replacement surgeries. You used several techniques of aortic valve replacement. You also carefully match the patients to the best surgical technique. There are several aortic valve replacement methods. What are the risk factors for aortic valve replacement operation? Dr. Anton Titov, MD. How do you match patients with a method of surgical operation? How do you minimize surgical risks for the patient? Dr. Jürgen Ennker, MD. Yes, it’s very important! The patient, of course, is the most important risk factor. The anatomical situation of the aortic valve is important for the surgeon to understand. Are there substantial calcifications of the heart valve? Is there only the aortic valve insufficiency? The aim is to replace the diseased valve with a valve with a very large valvular orifice. Dr. Jürgen Ennker, MD. I found the Medtronic Freestyle aortic valve. It came on the market in 1994. Two years later, in 1996, I started to implant this aortic valve. This is a stentless heart valve. It is actually just a root of the pig valve. It has a heart valve surface treatments. So it's not antigenic. You don't need a stent. This saves you an internal diameter. A patient receives a Freestyle aortic valve. It has a larger internal diameter. It has a bigger intraannular space. This means less gradients and more rapid recovery of the diseased myocardium. Faster recovery of patient after aortic valve implantation. So this is very important. In addition to this, a unique feature of the Freestyle valve is that it comes as a total aortic root. So you can use it for a root replacement in patients with aortic root aneurysm. Dr. Jürgen Ennker, MD. You can get rid of aortic root aneurysm by two techniques. The first one is total aortic root replacement. You resect the native aortic root of the patient. Then you have to implant again the coronary ostia. The other technique is the so-called aortic root inclusion. You implant the Freestyle heart valve inside the patient's aortic root. Of course, you have to re-implant the coronary ostia as well. So this is one indication. Another indication for aortic stenosis heart surgery is this. The patient may suffer from patient-prosthesis mismatch. Patients who have a very small annular aortic valve surface (annular diameter) need an aortic root enlargement. Freestyle heart valve is excellent. It is adapted for this enlargement of aortic root. Because you can cut into the noncoronary sinus. Then you can implant a larger Freestyle valve. It is better in comparison to a typical stented valve. Dr. Jürgen Ennker, MD. You can use a noncoronary sinus of the Freestyle valve as a replacement of the noncoronary sinus of the patient. Then you have enlargement by one of two grades larger than with typical normal stented heart valves. So this is a big advantage. Again, this contributes to better patient survival. Because the patient does much better after implantation of this heart valve in comparison to a routine stented aortic valve surgery. Thank you for this very good review of the technologies to replace aortic valve. You reviewed important heart valves that are used in aortic valve replacements. You have also identified a number of patient-side risk factors. They predict the risks of aortic valve replacement operations. In particular, patient's age predicts success of heart surgery. Dr. Anton Titov, MD. You also studied and published it extensively. What are the patient-side risk factors for aortic valve replacement surgical operation? Dr. Jürgen Ennker, MD. For patient risk factors, we have risk factor scores. In Europe we are using the euroSCORE. In United States, you are using the Parsonnet score. There are several patient-related risk factor variables. This is age, renal disease, pulmonary disease, reoperation, the state of their heart as graded by the New York Heart Association, Class 2, 3, or 4. Dr. Anton Titov, MD. Are there previous myocardial infarctions? Dr. Jürgen Ennker, MD. You have a number of different variables. So you can calculate the risk score. I started working in Lahr clinic. We started to calculate the patients' risk factors for heart surgery. We are able to give a patient a risk score as a number. This score reflects a risk that patient will have in our hospital. It is based on the experience of more than 15,000 cardiac operations. So everybody could make a decision about surgical operation. This decision is based on patient's personal risk. It is due to patient's personal risk factors. This is what we should tell our heart surgery patients. So that every patient can make an adequate decision whether do undergo heart surgery or not.