Patients in the stentless group received a larger valve prosthesis The bypass time and cross-clamp time were about 10 minutes longer in the stentless group. Long-term outcomes of various stentless bioprostheses have been reported Table 1. A randomized trial supported improved survival of patients with stentless valves. Lehman et al 39 compared the Freestyle or Toronto valves with Carpentier—Edwards porcine valves. On the contrary, another randomized study did not show improved clinical outcomes for up to 12 years.
Although improved hemodynamic outcomes were obtained in patients with a Toronto SPV valve, clinical outcomes were similar in both groups. The long-term results over more than 10 years were excellent with the Freestyle valves. LV hypertrophy and increased LV mass were highly correlated with sudden death, congestive heart failure, stroke, myocardial infarction, coronary artery disease, and other cardiovascular events.
Early postoperative hemodynamic performance was not different between stentless and stented valves, though implanted valve size was larger in stented AVR. Subcoronary implantation of stentless prostheses does not necessarily allow for larger valve selection compared with stented valves, because the LV outflow suture line is within the aortic annulus. The stented valves can be placed in a supra-annular position, upsizing from the true aortic annular size.
New-generation Carpentier—Edwards Perimount Magna Edwards Life-sciences, Irvine, CA valves had a better hemodynamic performance compared with stentless Edwards Prima Plus Edwards Lifesciences valves regarding pressure gradient and effective orifice area. A full-root technique can implant a larger stentless valve in the supra-annular position, allowing upsizing, compared with the original aortic annulus.
In randomized studies, better hemodynamic results were obtained with Freestyle, 57 , 60 Sorin Freedom, 21 Prima Plus, 48 , 61 , 62 and Toronto SPV valves 20 , 43 compared with stented valves. Although Freestyle valves showed a greater reduction in peak velocity and a greater increased effective orifice area than Mosaic porcine valves, there was a similar reduction in LV mass index and clinical outcomes at 6 months and 12 months after the operation.
Sorin Freedom stentless valves had a better pressure gradient and effective orifice area than Sorin More stented valves. There was no difference in mean pressure gradient and LV mass 8 weeks postoperatively.
Similar results were obtained by Doss et al 61 and Risteski et al 62 in patients over the age of 75 years. The effective orifice area, mean pressure gradient, and LV mass index were similar 12 months after the operation. Stentless valves showed no pressure gradient during dobutamine stress echocardiography in comparison with elevated transvalvular gradient in mechanical valves. There was a significant increase of pressure gradient in the stented valve group under exercise, though the native valve group and the stentless valve group showed no increase in pressure gradient under exercise.
An improved hemodynamic performance resulted in faster LV mass reduction in patients with aortic stenosis and LV hypertrophy. Primary tissue failure is an important issue after biological valve implantation Table 2. Theoretically, xenogenic stentless aortic valves have better durability by avoiding stress at the stent sites.
Urgent or emergent reoperation was necessary due to hemolytic anemia and congestive heart failure. The information of durability of xenogenic stentless valves in younger patients is absent because the majority of these valves are replaced in patients older than 50 years.
Only Vrandecic et al 18 reported the better durability of Biocor stentless bioprostheses than of its counterparts in patients with a mean age of Although long-term results of homograft aortic valves are excellent, faster calcification in homografts has been reported compared with Freestyle stentless valves in a younger age group. Homografts have been believed to be the substitute of choice in patients with active infective endocarditis.
However, there was no difference in susceptibility to infection between homografts and mechanical valves. Stentless bioprostheses were thought to replace stented biological valves by better hemodynamic performance and longer durability when they were introduced in the early s. The durability of long-term outcomes was not better than expected.
A demanding, cumbersome technique prolongs cardiac ischemic and bypass time and increases risk to the patient. Most surgeons now tend to implant stented valves in complicated cases and octogenarians, knowing that operative mortality and durability are not worse than with stentless AVR. Stentless valves with an easier implantation technique one suture line or sutureless may increase the market of stentless bioprostheses in the future.
There was no level I or IIa evidence of better hemodynamic performance, LV mass regression, surgical risk, durability, and late outcomes. At present, stentless bioprostheses are recommended in relatively young and active patients with impaired LV function and small aortic annulus. Bioprostheses for transcatheter aortic valve implantation does not have long-term outcomes.
Autologous pericardial stentless valves should also be limited to younger age groups of patients aged less than 50 years. National Center for Biotechnology Information , U. Vasc Health Risk Manag. Published online Jun 2. Junjiro Kobayashi. Author information Article notes Copyright and License information Disclaimer.
Received Jun 1. This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited. This article has been cited by other articles in PMC. Abstract Although porcine aortic valves or pericardial tissue mounted on a stent have made implantation techniques easier, these valves sacrifice orifice area and increase stress at the attachment of the stent, which causes primary tissue failure. Keywords: cardiopulmonary bypass, valves, heart disease, surgery, follow-up studies.
Introduction Homografts for aortic valve replacement AVR were the first biologic stentless prostheses used in clinical practice in the s. Operative outcomes Reports of the operative mortality of stentless and stented AVR have differed in the literature. Long-term outcomes Long-term outcomes of various stentless bioprostheses have been reported Table 1.
Table 1 Comparison of stented and stentless valves. Open in a separate window. Hemodynamic advantages LV hypertrophy and increased LV mass were highly correlated with sudden death, congestive heart failure, stroke, myocardial infarction, coronary artery disease, and other cardiovascular events.
Degeneration and durability Primary tissue failure is an important issue after biological valve implantation Table 2. Recommended indication of stentless valves Homografts have been believed to be the substitute of choice in patients with active infective endocarditis. Footnotes Disclosure The author discloses no conflicts of interest.
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Comparison of late outcome after stentless versus stented xenograft aortic valve replacement. Stentless vs stented aortic valve replacement: left ventricular mass regression. Asian Cardiovasc Thorac Ann. Stentless aortic valve are hemodynamically superior to stented valves during mid-term follow-up: a large retrospective study. Stentless and stented aortic valve replacement in elderly patients: factors affecting midterm clinical and hemodynamical outcomes.
Stentless versus conventional xenograft aortic valve replacement: midterm results of a prospectively randomized trial. Are stentless valves hemodynamically superior to stented valves? Long-term follow up of a randomized trial comparing Carpentier-Edwards pericardial valve with Toronto stentless porcine valves.
Retrospective and prospective randomized controlled studies showed similar operative mortality and morbidity in stented and stentless aortic valve replacement AVR , though stentless AVR required longer cross-clamp and cardiopulmonary bypass time.
Several cohort studies showed improved survival after stentless AVR, probably due to better hemodynamic performance and earlier left ventricular LV mass regression compared with stented AVR.
However, there was a bias of operation age and nonrandomization. A randomized trial supported an improved 8-year survival of patients with the Freestyle or Toronto valves compared with Carpentier-Edwards porcine valves.
On the contrary, another randomized study did not show improved clinical outcomes up to 12 years. Cusp tear with consequent aortic regurgitation was the most common cause of structural valve deterioration. Cryolife O'Brien valves also have shorter durability compared with stent valves. Early prosthetic valve failure was also reported in patients who underwent root replacement with Shelhigh stentless composite grafts.
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