The David Procedure for Aortic Valve Sparing & Root Replacement
The David procedure is a method of replacing the aortic root while sparing the aortic valve. Cardiac surgeon Dr. Tirone David developed the technique at the Toronto General Hospital. Patients with aortic regurgitation (insufficiency) or an aortic aneurysm are often candidates for a David procedure. The David procedure can also be beneficial for those with Marfan syndrome, a disorder that affects connective tissue and can lead to various problems with the valves in the heart and the aorta.
Since patients with this disorder may also have problems with the adherence of a prosthetic valve, surgeons typically strive to repair, rather than replace, their valves and often opt to perform a David procedure.
The Benefits Of The David Procedure
The David procedure conceived by Dr. Tirone David preserves the patient's aortic valve by making any necessary repairs to the valve and then reconnecting it to a healthy section of the aortic root. Since many patients receiving an aortic valve replacement must take anticoagulants for the balance of their lives, retaining the natural valve by performing a David procedure can spare them the complications that such medications can cause. For example, anticoagulants can be hazardous when taken during pregnancy.
The Surgical Approach Of The David Proceure
During the David procedure, the patient will be placed on cardiopulmonary bypass, or a heart-lung machine. The machine will keep oxygen and blood flow regulated during the surgery. With a David procedure, the aortic valve is clamped and the aorta is divided above the coronary arteries. Small pieces of tissue are removed from the coronary ostia, or openings. The ascending aorta is then removed. A graft is sutured in place, to which the valve can then be attached. The surgeon makes any customizations needed and the coronary arteries are reattached. During a David procedure, the portion of the aorta containing the aortic valve is not detached from the heart.
The Modified David Procedure
The modified David procedure was not developed by Dr. Tirone David but by Dr. Lars G. Svensson of Cleveland Clinic. The modified David procedure is similar to the original David procedure. Although the David procedure provides the patient with numerous benefits, it is a technically challenging surgery. By reducing the difficulties a surgeon might encounter, the modified David procedure provides patients with greater access to a valve-sparing technique. The modified David procedure takes advantage of a special device, known as a Hegar's dilator.
The surgeon places the dilator through the aortic valve into the outflow tract of the left ventricle. The dilator's size is determined by the average size of the tract in relation to the size of the patient. The surgeon can then shape the bottom of the graft to more closely resemble the aorta's natural dimensions by tying sutures around the dilator.Preliminary results indicate that the modified David procedure produces successful results. Using the dilator as part of the modified David procedure ensures proper sizing of the outflow tract, greater normalcy of the aortic root, and improvements in valve functionality.
About Dr. Tirone David
Dr. Tirone David, a native of Brazil, received his medical degree from the Universidade Federal do Parana. He received further training in thoracic and cardiovascular surgery at Ohio's Cleveland Clinic between 1970 and 1975 before immigrating to Canada and joining the Toronto General Hospital as a cardiovascular surgeon. He also teaches at the University of Toronto. An Officer of the Order of Canada, Dr. Tirone David has also received the Order of Ontario. He is a former president of the American Association of Thoracic Surgeons and is the current head of cardiovascular surgery for Toronto General Hospital. Dr. Tirone David has also performed surgery in a live Internet presentation, and often travels internationally to demonstrate his techniques to other surgeons. He has also authored numerous papers and book chapters on the David procedure and heart surgery in general.