Valve-sparing aortic root replacement: What patients need to know

Alberto Pochettino, M.D., Cardiovascular Surgery, Mayo Clinic: My name is Alberto Pochettino. I’m a cardiovascular surgeon at Mayo Clinic in Rochester, Minnesota. I have a special interest in aortic surgery and today I will discuss the operation known as valve-sparing aortic root replacement. The aortic root is the beginning of the aorta. It is located at the transition between the main pumping chamber of the heart and the remainder of the aorta. It contains the aortic valve and the origin of the coronary arteries. Replacement of the aortic root is indicated in the presence of an aortic aneurysm. An aneurysm is an abnormal enlargement of a blood vessel. The maximum diameter of the aneurysm is used to assess the risk of rupture or dissection. At the level of the aortic root, 5.5 centimeter in maximum diameter is felt to be the size at which replacement surgery should be performed in most patients. Conditions in which the aortic wall is intrinsically weaker mandate intervention at a lower size. Most of these conditions are due to genetic abnormality of the aortic wall. The classic abnormality is Marfan syndrome but other rare abnormalities have been defined such as Ehlers-Danlos syndrome, Loeys-Dietz syndrome and a few others. However, by far the most common genetic aortic abnormality affecting the aortic root is bicuspid aortic valve disease. In all of these patients with higher risk condition, the trigger for surgical intervention should be lowered to 5 centimeter for many bicuspid aortic valve and 4.5 centimeter for most Marfan and other more severe genetic abnormalities.

Historically, replacement of the aortic root require replacement of the aortic valve contained within it, even when the valve may not have been significantly diseased. In younger individuals, a mechanical aortic valve would have been recommended because of its durability but it requires life-long anticoagulation with blood thinners such as coumadin. The alternative tertiary valve would not require coumadin but has limited lifespan necessitating reoperation. The reluctance to replace the aortic root when found within the normal aortic valve prompted development in 1980s of techniques to spare the native valve. The first attempt came to be known as “remodeling” followed by the reimplantation technique first reported by Tirone David. The reimplantation technique, over subsequent years, has proved to be the most durable. The surgical principle is to replace the entire aortic root from the ventricular annular junction to the so-called sinutubular junction with a Dacron graft tube. Within this tube, the three-dimensional aortic valve is reimplanted, thus the name. Over the subsequent years, the aortic root reimplantation, sometimes known as David operation, has been shown to be safe and effective in a specialized center performed by dedicated aortic surgeons. While long-term results have been very positive, in some patients, the native aortic valve may still deteriorate requiring long-term monitoring and, in some individuals, eventual replacement. Over the years, factors have been identified that impact the successful outcome of the procedure. For example, the larger the aneurysm, the more distortion the aortic valve leaflet will suffer leading to worse aortic valve insufficiency. The more long-standing aortic insufficiency, the more fibrosis and abnormality occur in the leaflets leading to a lower success in sparing the valve and a lower long-term durability of the spared valve. This has led to earlier intervention in select patients to allow for a durable valve function within the replaced root.

Despite this general tendency of earlier surgery, my practice has continued to use maximum aortic diameter combined with genetic risk factors to justify root replacement. Early in the development of valve-sparing root replacement, bicuspid aortic valves were not considered eligible due to the intrinsic abnormality of those valves. More recently good results have been achieved in the treatment of root aneurysm where bicuspid aortic valves are well functioning. While long-term outcomes in this set of patients may be less optimal than in the trileaflet aortic valve, a spared bicuspid valve is likely to be quite durable as well. Unfortunately a significant fraction of bicuspid valves in patients with root aneurysm are not normal and still require valve replacement.

In summary, the aortic root replacement should be dictated by the size of the aortic root aneurysm as well as the genetic risk factors. When the aortic valve leaflets are of good quality and can be spared, they should be. However, if the leaflets have significant abnormalities and the repair is not likely to be durable, the valve should be replaced with an appropriate prosthesis to meet the needs of the individual patient. Clinical judgment should be used both when deciding when to operate such that premature intervention is avoided as well as at surgery to maximize the benefit to the patient even if that may occasionally mean replacement of the aortic valve.