Weltert Luca, Nardella Saverio, Girola Fabiana, Scaffa Raffaele, Bellisario Alessandro, Maselli Daniele, De Paulis Ruggero
Cardiac Surgery Department, European Hospital, Rome, Italy.
J Heart Valve Dis. 2012 Jan;21(1):99-105.
Currently, little is known of the diastolic properties of stentless valves that affect stress and strain on leaflets and, hence, their durability. In a pressurized aortic root model, a series of in-vitro tests was conducted to determine how stentless valves behave in diastole, and how they adapt to different annulus-to-sinotubular junction (STJ) ratios.
Sixteen 25 mm stentless aortic valves (four each of the Sorin Solo, ATS 3F, Edwards Prima Plus and Medtronic FreeStyle) were sutured into a 32 mm Valsalva graft, suspending the commissures into the expandable region (42 mm). The neoaortic root was pressurized and the size of the STJ progressively reduced by wrapping the neocommissural ridge with Dacron rings. Endoscopic views and ultrasound imaging were used to observe the geometry of the leaflets, regurgitation, and the height and level of leaflet coaptation at different annulus-to-STJ ratios.
Pericardial prostheses built to mimic a cylinder (ATS 3F and Sorin Solo) showed the greatest tolerance to STJ dilatation and a larger coaptation surface, but also a tendency to roll in on themselves in an italic S-shape if oversized. Valves built to mimic native aortic leaflets (porcine Prima Plus and Medtronic Freestyle) showed a reduced tolerance to STJ dilatation, resulting in regurgitation and a smaller coaptation surface, but also a reduced tendency to roll if oversized.
Despite similar systolic performances, stentless prostheses behave differently during diastole. The 3F and Solo valves benefit from a better tolerance to STJ dilatation, while the Prima Plus and Freestyle benefit from a more stable shape of closure under conditions of oversizing.
目前，对于无支架瓣膜舒张特性影响瓣叶应力和应变进而影响其耐久性的情况知之甚少。在一个加压主动脉根部模型中，进行了一系列体外试验，以确定无支架瓣膜在舒张期的表现，以及它们如何适应不同的瓣环至窦管交界（STJ）比值。
将16个25毫米的无支架主动脉瓣膜（索林Solo、ATS 3F、爱德华兹Prima Plus和美敦力Freestyle各4个）缝合到一个32毫米的瓦尔萨尔瓦移植物中，将瓣叶连合部悬吊到可扩张区域（42毫米）。对新主动脉根部进行加压，并通过用涤纶环包裹新瓣叶连合嵴来逐渐减小STJ的尺寸。使用内镜观察和超声成像来观察不同瓣环至STJ比值下瓣叶的几何形状、反流情况以及瓣叶对合的高度和水平。
设计成模仿圆柱体的心包瓣膜（ATS 3F和索林Solo）对STJ扩张的耐受性最强，对合面较大，但如果尺寸过大，有自身呈斜S形内卷的趋势。设计成模仿天然主动脉瓣叶的瓣膜（猪源Prima Plus和美敦力Freestyle）对STJ扩张的耐受性降低，导致反流且对合面较小，但尺寸过大时内卷趋势减弱。
尽管收缩期性能相似，但无支架人工瓣膜在舒张期的表现有所不同。3F和Solo瓣膜受益于对STJ扩张更好的耐受性，而Prima Plus和Freestyle瓣膜在尺寸过大的情况下受益于更稳定的关闭形状。
