Native Aortic Valve Resection Using a Novel Blade-Based Device.

OBJECTIVE: The aim of this study was to validate the use of a new resection device in patient candidates for surgical aortic valve replacement. We evaluated the efficacy of this new circular blade to resect the aortic valve and the efficacy to collect the debris during the resection. METHODS: For this study, a single size instrument was used, with an external diameter of 22 mm, and patients were selected on the basis of the preoperative assessment of the aortic diameters. RESULTS: From October 2018 to June 2019, 10 patient candidates for surgical aortic valve replacement were selected to undergo native aortic valve resection using a new device, before surgical valve implantation. The mean age of the patients was 74 ± 7.6 years, and 8 of 10 were male. The mean aortic annulus diameter, measured before the procedure, was 25.7 ± 1.57 mm. The resection was complete in 9 (90%) patients. In 1 patient, due to an imprecise positioning of the device, the valve resection was partial. None of the patients showed signs or symptoms due to debris embolism. In all patients, the postoperative course was uneventful. CONCLUSIONS: These preliminary results show that resection of the aortic valve using a circular foldable blade is feasible. This prototype, used during conventional surgery even through a small incision, provided an efficient tool to easily resect the valve without debris release.

Free margin length and geometric height in aortic root dilatation and leaflet prolapse: implications for aortic valve repair surgery.

OBJECTIVES: Our goal was to assess the aortic leaflet free margin length (FML) and geometric height (gH) in a normal aortic valve (AV), aorta dilatation and aortic leaflet prolapse. METHODS: We measured the FML and gH intraoperatively in 132 patients operated on for aortic insufficiency, aortic dilatation, endocarditis or fibroelastoma. Patients were divided into 3 groups: normal tricuspid AV (group 1, n = 12), aortic dilatation (group 2, tricuspid = 43, bicuspid = 18) and leaflet prolapse (group 3, tricuspid = 32, bicuspid = 27). The FML and gH were compared between the groups and between the leaflets within each group. RESULTS: In a normal tricuspid AV, the mean FML and gH were 34.7 ± 3.1 mm and 18.8 ± 1.7 mm, respectively. In group 2 tricuspid, the FML and gH were greater than those in group 1 (FML 43.7 ± 4.4, P < 0.001; gH 21.2 ± 1.8, P = 0.003). In group 3, tricuspid, the FML of the prolapsing leaflet was greater than the FML of the non-prolapsing leaflet (48.3 ± 5.4 vs 42.2 ± 3.6; P < 0.001). In group 2, bicuspid, FML of both leaflets were similar in group 2, but augmented on the fused leaflet compared to the non-fused leaflet in group 3 (fused 55.4 ± 6.3; non-fused 46.2 ± 6.2; P < 0.001). In groups 2 and 3 bicuspid, the gH of the non-fused leaflet was systematically greater than the fused leaflet (group 2 non-fused 24.6 ± 2.5 vs fused 20.4 ± 2.1; P < 0.001). CONCLUSIONS: In aortic dilatation and leaflet prolapse, FML and, to a lesser extent, gH increased significantly compared to those of normal AV function. FML and gH dimensions also depended on the valve configuration (tricuspid/bicuspid). These data provide new insight into the pathomorphology of AV disease and will serve to further develop new methods of AV repair based on intraoperative measurements of the FML.

Porcine pulmonary valve decellularization with NaOH-based vs detergent process: preliminary in vitro and in vivo assessments.

BACKGROUND: Glutaraldehyde fixed xenogeneic heart valve prosthesis are hindered by calcification and lack of growth potential. The aim of tissue decellularization is to remove tissue antigenicity, avoiding the use of glutaraldehyde and improve valve integration with low inflammation and host cell recolonization. In this preliminary study, we investigated the efficacy of a NaOH-based process for decellularization and biocompatibility improvement of porcine pulmonary heart valves in comparison to a detergent-based process (SDS-SDC0, 5%). METHODS: Native cryopreserved porcine pulmonary heart valves were treated with detergent and NaOH-based processes. Decellularization was assessed by Hematoxylin and eosin/DAPI/alpha-gal/SLA-I staining and DNA quantification of native and processed leaflets, walls and muscles. Elongation stress test investigated mechanical integrity of leaflets and walls (n = 3 tests/valve component) of valves in the native and treated groups (n = 4/group). Biochemical integrity (collagen/elastin/glycosaminoglycans content) of leaflet-wall and muscle of the valves (n = 4/group) was assessed and compared between groups with trichrome staining (Sirius Red/Miller/Alcian blue). Secondly, a preliminary in vivo study assessed biocompatibility (CD3 and CD68 immunostaining) and remodeling (Hematoxylin and eosin/CD31 and ASMA immunofluorescent staining) of NaOH processed valves implanted in orthotopic position in young Landrace pigs, at 1 (n = 1) and 3 months (n = 2). RESULTS: Decellularization was better achieved with the NaOH-based process (92% vs 69% DNA reduction in the wall). Both treatments did not significantly alter mechanical properties. The detergent-based process induced a significant loss of glycosaminoglycans (p < 0,05). In vivo, explanted valves exhibited normal morphology without any sign of graft dilatation, degeneration or rejection. Low inflammation was noticed at one and three months follow-up (1,8 +/- 3,03 and 0,9836 +/- 1,3605 CD3 cells/0,12 mm2 in the leaflets). In one animal, at three months we documented minimal calcification in the area of sinus leaflet and in one, microthrombi formation on the leaflet surface at 1 month. The endoluminal side of the valves showed partial reendothelialization. CONCLUSIONS: NaOH-based process offers better porcine pulmonary valve decellularization than the detergent process. In vivo, the NaOH processed valves showed low inflammatory response at 3 months and partial recellularization. Regarding additional property of securing, this treatment should be considered for the new generation of heart valves prosthesis. Graphical abstract of the study.

Free margin length and coaptation surface area in normal tricuspid aortic valve: an anatomical study.

OBJECTIVES: Aortic cusp free margins are a central target in most aortic valve repair operations to optimize valve coaptation. The objective of this anatomical study was to analyse the normal dimensions of free margin length (FML) and coaptation surface and to analyse their relationship with other valve and root dimensions in normal tricuspid aortic valves. METHODS: We analysed 25 aortic root homografts. Eight valve and root measurements were obtained from fresh specimens including the length of the free margin while applying appropriate tension on the structures. The valves were then fixed with formalin in the diastolic position under pressure to allow measurement of the coaptation surface. In addition to normal values, we analysed the correlations and ratios between the different measures. RESULTS: The mean FML was 34.3 ± 3.1 mm. The FML was similar between the 3 cusps and correlated with all other valve and root measures. The ratio of the FML to the geometric height was 1.81, and the free edge length/sinotubular junction was 1.29. The mean coaptation surface was 122 ± 21 mm2 per cusp and corresponded to 41% of the cusp surface. The central coaptation length was 3.3 ± 0.8 mm, and the lateral coaptation length was 5.9 ± 0.6 mm. The total coaptation surface per specimen was 184 ± 32 mm2. CONCLUSIONS: We described the normal dimensions of the FML and coaptation surface in the tricuspid aortic valve. These measurements will serve in the further development of an objective method of free margin shortening based on intraoperative measurements of the FML to treat cusp prolapse and low coaptation after valve-sparing surgery.

CorMatrix valved conduit in a porcine model: long-term remodelling and biomechanical characterization.

OBJECTIVES: Porcine small intestinal submucosa extracellular matrix (CorMatrix; CorMatrix Cardiovascular, Rosewell, GA) is a relatively novel tissue substitute used in cardiovascular applications. We investigated the biological reaction and remodelling of CorMatrix as a tri-leaflet valved conduit in a pig model. We hypothesized that CorMatrix maintains a durable architecture as a valved conduit and remodels to resemble surrounding tissues. METHODS: We fashioned the valved conduit using a 7 × 10 cm 4-ply CorMatrix sheet and placed it in the thoracic aorta of seven landrace pigs for 3, 4, 5 and 6 months. Biodegradation, replacement by native tissue, strength and durability were examined by histology, immunohistochemistry and mechanical testing. RESULTS: Four pigs, one per time frame, completed the study. The conduit lost its original architecture as a tri-leaflet valve due to cusp immobility, subsequent attachment to the wall segment and consequent maintenance of a thick arterial wall-like structure. Scaffold resorption was incomplete, with disorganized inconsistent spatial and temporal degradation even at 6 months. Fibrosis, scarring and calcification started at 4 months and chronic inflammation persisted. The partially remodelled scaffold did not resemble the aortic wall, suggesting impaired remodelling. Mechanical testing showed progressive weakening of the tissues over time, which were liable to breakage. CONCLUSIONS: CorMatrix is biodegradable; however, it failed to remodel in a structured and anatomical fashion in an arterial environment. Progressive mechanical and remodelling failure in this scenario might be explained by the complexity of the conduit design and the host's chronic inflammatory response, leading to early fibrosis and calcification.

Endovascular resection of the native aortic valve before transcatheter aortic valve implantation: state of the art and review.

Transcatheter aortic valve implantation was introduced into clinical practice in 2002 as a rescue approach in patients presenting with symptomatic severe aortic stenosis but not eligible for conventional aortic valve replacement. This technique allows implantation of a balloon expandable bioprosthesis without resection of the native aortic valve. Several complications are described as a consequence of the residual highly calcified valve being squeezed against the aortic wall by the stent of the implant. This can result in deformation of the metal stent and paravalvular leakage, risk of occlusion of the coronary ostia, or central and peripheral embolization of valvular debris. To avoid these complications, many authors suggest the possibility to resect and remove the native aortic valve before transcatheter aortic valve implantation. In this field, different authors have described possible techniques and different sources of energy to resect the calcified valve. In this article, we review the development of these experimental techniques and discuss future prospects in this field.