When a patient needs their aortic valve replacing, using the valve in their own pulmonary artery for the replacement leads to better survival and quality of life than if the aortic valve from a dead donor is used. This is the conclusion of an Article published Online First and in an upcoming edition of The Lancet, written by Professor Sir Magdi Yacoub, Royal Brompton and Harefield NHS Foundation Trust, London, UK, and Imperial College London, UK, and colleagues.
The aortic valve is one of the two valves of the heart, the other being the pulmonary valve. The aortic valve connects the left ventricle of the heart to the body's main artery, the aorta. Aortic valve replacement has been shown to improve the natural history of patients with severe symptomatic aortic valve disease. With the increase in the global population and improved access to health care, the number of aortic valve surgeries worldwide is estimated to triple within the next 30 years. So far, surgery remains the only effective solution for improvement of the natural history of the disease; however, survival after surgery is often worse than in the general population.
The ideal substitute for aortic valve replacement in patients with aortic valve disease is not known. Valve replacements can be tissue-based, or mechanical. Some three quarters of all replacement valves are tissue-based, but mechanical valves remain popular in some centres. For tissue-based valves, the authors hypothesised that the regulatory and adaptive properties of a living valve substitute (autograft) could improve the long-term outcomes in patients more than those of a valve harvested from a dead donor patient (homograft). In this study, these two options were compared.
Male and female patients (<69 years) requiring aortic valve surgery were randomly assigned in a one-to-one ratio to receive an autograft (using the ross procedure-see description below) or a homograft aortic root replacement in one centre in the uk (royal brompton and harefield nhs foundation trust, london,uk). the primary endpoint was survival of patients at 10 years after surgery. all the surgeries were open-heart.
In those receiving the a living valve or autograft, their own malfunctioning aortic valve was removed and replaced with the patient's own pulmonary valve (which connects the heart to the pulmonary artery). Following this, their own pulmonary valve was replaced with a pulmonary valve donated from a dead patient. Patients receiving the 'dead' valve or homograft had their aortic valve replaced with an aortic valve donated from a dead patient.
A total of 228 patients were randomly assigned to receive an autograft or a homograft aortic root replacement. 12 patients were excluded because they were younger than 18 years; 108 in each group received the surgery they were assigned to and were analysed. There was one (<1%) death during or just after surgery in the autograft group versus three (3%) in the homograft group. at 10 years follow-up, four patients died in the autograft group versus 15 in the homograft group, statistically this meant patients given a homograft were more than four times more likely to die than those given an autograft. survival at 10 years was 97% in the autograft group versus 83% in the homograft group. survival of patients in the autograft group (97%) was similar to that in an age-matched and sex-matched general british population (96%).
The authors conclude: "The Ross procedure, compared with homograft aortic root replacement, improved survival in adults, and was associated with improved freedom from reoperation and quality of life... our results support the hypothesis that a living valve implanted in the aortic position can lead to significantly improved clinical outcomes in patients."
The authors add that they are also working on an a living tissue-engineered valve that can reproduce the functions of an autograft. This pioneering work involves populating a matrix (made of materials such as collagen) with stem cells, which eventually produces a valve to replicate the sophisticated functions of the normal autograft.
In a linked Comment, Dr Salvatore Lentini, Policlinic University Hospital, Messina, Italy, Messina, Italy, says: "The notion of a beneficial effect of a living heart valve and aortic root is now not only theoretical or hypothetical, but has also been shown clinically. The living valve theory might be used in the future, and not only for autografts. Continued research will probably soon help in the identification of living aortic valve substitutes, making implantation easy with respect to other portions of the heart, with the aim of increasing technique reproducibility and allowing more widespread use."