Aortic Valve Replacement with Stentless Porcine Bioprostheses

Aortic valve replacement with stentless porcine valve should provide superior hemodynamic results to stented porcine valve because the obstruction caused by the stent and the sewing ring is eliminated. In addition, the coronary sinuses of the recipient may allow for better dissipation of the mechanical stress to which the leaflets are subjected during diastole, thus enhancing durability of the heterograft. Aortic valve replacement with stentless glutaraldehyde-fixed aortic porcine bioprosthesis was carried out successfully in six young sheep. These animals were hemodynamically evaluated at 3 to 6 months after operation and found to have no resting gradients or any degree of aortic regurgitation. Explantation of the aortic heterograft revealed that it was well healed in the aortic root and had no evidence of any calcification. A clinical trial has been initiated and the results in the first five humans who underwent aortic valve replacement with a stentless porcine aortic bioprosthesis have been satisfactory.     

Aortic Valve Replacement with Stentless Porcine Bioprostheses

The implantation of stentless porcine valves (SPVs) is technically more demanding than implantation of stented bioprosthetic valves. Implantation of the Toronto SPV bioprosthesis requires an,understanding of the relationships between the leaflets and the aortic annulus and sinotubular junction. In addition to proper alignment of the three commissures within the aortic root, the diameter of sinotubular junction should not exceed the external diameter of the porcine aortic valve after completion of the operation. The Medtronic Freestyle porcine aortic root bioprosthesis can be used for subcoronary implantation as well as for aortic root replacement. Degenerative calcification of a tricuspid aortic valve is the most common cause of aortic valve disease in older patients. Implantation of stentless valves in the subcoronary position is usually feasible because the geometry of the aortic root is well maintained in these patients. The bicuspid aortic valve is the second most common cause of aortic valve disease in older patients and the most common in younger patients. These patients frequently have dilated aortic root, and the Medtronic Freestyle bioprosthesis is ideal for implantation using the root inclusion technique. Stentless porcine bioprostheses are minimally obstructive and associated with low mean systolic gradients. In addition, they have better hemodynamic performance during exercise than stented bioprostheses. For these reasons, patient-prosthesis mismatch has not been described with stentless valves. Left ventricular function after aortic valve replacement appears to be better with stentless than with stented bioprostheses. Comparative, nonrandomized studies of aortic valve replacement with stented and stentless valves suggest that the risk of cardiac death is reduced with stentless valves and the rates of valve-related complications also appear to be lower. What remains unknown is whether stentless valves are more durable than stented ones.     

Replacement of Ascending Aorta and Aortic Valve

Repair of an ascending aortic aneurysm involving the aortic valve can still present technical problems relating to optimal approach, choice of reconstructive technique, safety of the anastomoses, and achievement of an absolutely leakproof prosthesis. In this paper I will discuss these problems and ways to solve them.     

复合带瓣人工血管替换升主动脉和主动脉瓣(24例报告)

报告２４例升主动脉瘤伴主动脉瓣关闭不全行升主动脉和主动脉瓣替换及冠状动脉开口移植术（Ｂｅｎｔａｌ术２２例，底盘法２例）。１３例伴有升主动脉夹层分离，对其中８例ＤｅＢａｋｅｙＩ型者，以Ｔｅｆｌｏｎ毡条内外加固主动脉切端后吻合。１３例用人工血管周围间隙与右心耳吻合以控制升主动脉吻合之外的出血。３例以人工血管片环包主动脉吻合口控制局部广泛渗血及出血。２例术毕不能脱离体外循环死亡，手术死亡率８３％。随访平均２１８个月，２例死于蛛网膜下腔出血，１例右股动脉栓塞经手术治愈；其余病人康复良好，心功能（ＮＹＨＡ）Ｉ～ＩＩ级。     

Aortic Valve Replacement with the Unique Suture Line Stentless USL Porcine Valve: A New, Simple, and Safe Stentless Valve Implantation Technique

The Stentless USL, Unique Suture Line porcine valve, is a stentless bioprosthesis developed following the advantages of the studies of the physiology of the aortic root as a functional unit. The direct suturing of the porcine tissue on the soft and elastic tissue of the host's aortic annulus and root gives the bioprosthesis the possibility to follow the physiological movements of the natural valve during the cardiac cycle. For the same reason, there is decreased stress on the valve tissue, especially at the commissural level. There is less technical demand for surgeons who have limited experience with the freehand or miniroot technique due to the limited availability of the homografts because the Stentless USL valve can be implanted with the same technique used with a conventional stented valve. The implant technique used for the Stentless USL valve has advantages, especially in the small aortic calcified annulus in elderly patients where the freehand technique can be difficult and the second suture line can be dangerous (i.e., coronary ostium near the aortic ring or in calcified aortic wall). Our experience with this stentless valve in approximately 200 patients (> 70 years old) shows it to have excellent hemodynamic results even in small valve sizes. The use of this valve and the simple implantation technique avoids the need for complicated aortic root enlargement procedures.     

Structural Valve Deterioration After Aortic Valve Replacement with Medtronic Freestyle Stentless Porcine Aortic Root Bioprostheses

The Medtronic freestyle aortic root bioprosthesis (Medtronic, Inc., Minneapolis, MN, USA) is a stentless valve with an effective orifice area that is larger than that observed on other bioprostheses. However, there have been sporadic reports of structural valve deterioration (SVD), such as aortic root wall rupture, leaflet tearing, and pseudoaneurysm formation. We report five cases of SVD of freestyle aortic root bioprostheses. doi: 10.1111/jocs.12235 (J Card Surg 2014;29:22‐25)