**9. Conclusion**

in subcoronary, 92.3% ± 6.0% in full-root, and 92.0% ± 10.7% in root inclusion groups; p = 0.82) and from structural valve deterioration (97.0% ± 2.2% in subcoronary, 96.0% ± 4.5% in full-root, and 90.9% ± 11.2% in root inclusion groups; p = 0.54) are similar between implants techniques

The truly stentless autologous pericardial aortic valve may be better choice in patients who cannot or do not want to take anticoagulation, especially young population, because excellent long-term durability and easier reoperation, which is technically undemanding compared to other stentless bioprostheses. The use of autologous pericardium avoids any immune reaction between the host and the implanted valve, and minimizes tissue calcification and pannus formation, which are important causes of structural valve deterioration. The absence of a stent and sewing ring is also helpful for long-term durability with a freedom from structural valve deterioration of 100% at 7.5 years [11]. Long-term durability seems better than the other bioprostheses because it has been reported that there is no calcification, no structural dys‐ function on the autologous pericardium used for aortic leaflet extension at 13 years [94]. Reoperation must be easier because there is no calcification on the aorta and pericardial aortic

The advantage of stentless xenografts is providing a greater EOA index for a given valve size, which results lower transvalvular gradients compared with stented valves. These improve‐ ments have been reported in a meta analysis: lower mean aortic valve gradient (-3.57 mmHg; p < 0.01), lower peak gradient (-5.8 mmHg; p< 0.01), but higher EOA index in stentless group compared with the stented [15]. It has been shown in an experimental porcine model that the annular cross-sectional area of stentless valves is significantly larger than stented valves [23]. The EOA will increase after first postoperative year in stentless valves and significant differ‐ ences in mean and/or peak pressure differences between stentless and stented valves will

The Freedom SOLO stentless bioprosthesis with all size-number has a lower mean (10.6 ± 3.6 mmHg) and peak (15.9 ± 9.1 mmHg) transvalvular gradient at discharged, and below 10 mmHg in all sizes (21-27 mm) at the first postoperative year [97]. The similar results have been shown by other groups: lower mean gradient (6.7 +/- 4.1 mmHg) and a significant regression of left

3f aortic bioprosthesis has a satisfactory hemodynamic performance with substitutes larger than 23 mm (< 10 mmHg), but smaller valves have a significant higher mean transvalvular gradient at the 4-postoperative year (18 mmHg for 21 mm and 14 mmHg for 23 mm devices) [36]. The left ventricular mass index decreases during follow-up (showed 18% regression), but cannot reach the normal range, especially with small devices. In another study with a mean valve size 26.0 ± 1.9 mm has shown that the mean transvalvular gradient of 3f bioprostheses

The Edwards Prima Plus stentless valve bioprosthesis is a porcine aortic root cylinder and is associated with high early peak and mean transprosthetic gradients (37 ± 16 and 18 ±8 mmHg,

with the Freestyle stentless valves [91].

438 Calcific Aortic Valve Disease

**8.3. Echocardiographic outcomes**

continue during long-term follow-up [95,96].

ventricular hypertrophy (23%) at 12 months [98].

has increased at 5 years (15.2 ± 5.3 mmHg) [99].

valve.

Aortic valve replacement means that native valve disease is replaced with prosthetic valve inadequacy affected by prosthetic valve hemodynamics, durability, and thrombogenicity. Stentless bioprostheses have better hemodynamic properties because of larger effective orifice area, better coronary flow, lower transvalvular gradient and better left ventricular mass regression than stented bioprostheses. They have also better biomechanical properties and the preserved distensibility may diminish stress considerably. Valve-related morbidity and structural valve degeneration are not worse than stented valves, but their implantation is demanding and required experience in this field. Although experienced centers give excellent results with stentless xenografts, most surgeons also prefer a stented xenograft to keep the procedure quick, safe, and simple. But, there is a trend to favor stentless valves nowadays because these valves provide larger effective orifice area, lower transvalvular gradients and excellent hemodynamics which stimulate rapid and effective reduction in left ventricular hypertrophy. It seems that the usage of stentless valves has more advantages in patients with impaired left ventricular function, small aortic, or aortic root abscess or more active patients. In future, using of stentless valves will increase with simpler implantation techniques, increased surgical experience, new design of prostheses, may be, using sutureless valves.

ment. Results from a Prospective Randomized Trial. Journal of American College of

Stentless Bioprostheses for Aortic Valve Replacement in Calcific Aortic Stenosis

http://dx.doi.org/10.5772/55373

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