Composite aortic root replacement has become the gold standard operation for patients with Marfan syndrome and aortic root aneurysms. With an operative risk in the low single digits when performed in high-volume centers under elective circumstances, it is a cornerstone in the prevention of the dreaded complication of acute aortic dissection, which carries a mortality rate of 25% among those who make it to the hospital. But while the results are excellent, composite aortic root replacement is not an ideal solution.
The long-term results associated with composite root replacement are excellent and current prosthetic mechanical valves have almost unlimited durability. Reoperations following this procedure principally occur for the treatment of subsequent aneurysms of the remaining native aorta. The lifetime risk of reoperation on the prosthesis itself is approximately 5%. Reoperation is indicated for infection or for obstruction of the valve orifice or leaflet motion caused by scar tissue.
Because patients with Marfan syndrome undergoing root replacement are typically young, however, and mechanical valves require anticoagulation with warfarin, which is troublesome over a lifetime, particularly for women of childbearing age, there is a need for a treatment approach that eliminates the requirement for long-term anticoagulation. Bioprosthetic valves have limited durability, and the complexity of a repeat operation after root replacement discourages the use of these valves in young patients.
Among the most exciting developments in the surgical treatment of Marfan syndrome in recent years has been the refinement of techniques for valve-sparing root replacement.
The late 1970s brought the development of a valve-sparing root reconstruction procedure in which the diseased sinuses of Valsalva and ascending aorta were replaced with Dacron grafts, while the native valve leaflets were left intact. The results were excellent, with the anatomy on postoperative echocardiography being almost indistinguishable from normal. Unfortunately, patients with Marfan syndrome appear to be at considerable risk of late aortic insufficiency, probably because of progressive dilation of the aortic annulus.
An alternative reimplantation valve-sparing operation was first described in 1992. This procedure involves resuspending the aortic valve apparatus within the Dacron graft. Widely accepted as the preferred approach to valve-sparing procedures, reimplantation has become the technique of choice at Mayo Clinic.
Results associated with this valve-sparing approach have been so encouraging that the National Marfan Foundation (NMF) sponsored a multicenter trial to compare the results of the valve-sparing procedure with composite root replacement outcomes. Enrollment in the NMF study began in March 2005, and as of the June 2008 analysis (which included 202 enrolled patients, 32 from Mayo Clinic), 70% of patients had undergone a valve-sparing procedure. Of the remaining patients, most had replacement with a mechanical composite graft.
To date, no early deaths have occurred among study participants. There have been only 3 instances of valve dysfunction, 2 of which were secondary to failed valve-sparing procedures corrected intraoperatively. No late failures of the valve-sparing procedure have occurred thus far, although follow-up has been brief and is ongoing. Postoperative morbidity, including hospital stay, has been similar for both procedures, although the valve-sparing operation is more complex and requires a longer cross-clamp time.
Cardiovascular surgeons at Mayo Clinic have a long history of aortic repair with excellent morbidity and mortality rates. They have performed valve-sparing procedures since 1993, with numbers increasing over recent years as confidence in the long-term durability of the procedure builds.
The valve-sparing operation has become the preferred procedure in patients with Marfan syndrome. Currently 80% to 90% of native valves are spared in patients who have favorable anatomic characteristics. This group includes patients with Marfan syndrome as well as other causes of aortic root enlargement, such as familial thoracic aortic aneurysmal disease and bicuspid aortic valve disease. Valve-sparing surgery has become an important part of the aortic surgery program at Mayo Clinic.