Polyamines and microbiota in bicuspid and tricuspid aortic valve aortopathy.

Polyamines are small aliphatic cationic molecules synthesized via a highly regulated pathway and involved in general molecular and cellular phenomena. Both mammalian cells and microorganisms synthesize polyamines, and both sources may contribute to the presence of polyamines in the circulation. The dominant location for microorganisms within the body is the gut. Accordingly, the gut microbiota probably synthesizes most of the polyamines in the circulation in addition to those produced by the mammalian host cells. Polyamines are mandatory for cellular growth and proliferation. Established evidence suggests that the polyamine spermidine prolongs lifespan and improves cardiovascular health in animal models and humans through both local mechanisms, involving improved cardiomyocyte function, and systemic mechanisms, including increased NO bioavailability and reduced systemic inflammation. Higher levels of polyamines have been detected in non-dilated aorta of patients affected by bicuspid aortic valve congenital malformation, an aortopathy associated with an increased risk for thoracic ascending aorta aneurysm. In this review, we discuss metabolism of polyamines and their potential effects on vascular smooth muscle and endothelial cell function in vascular pathology of the thoracic ascending aorta associated with bicuspid or tricuspid aortic valve.

A word of caution using self-expanding transcatheter aortic valve-frame infolding.

Transcatheter aortic valve replacement has become a mainstay alternative to surgical aortic valve replacement in patients with severe aortic stenosis at high and intermediate surgical risk. Two commercially approved valves are available in the United States: balloon-expandable and self-expanding. We report here a rare complication of a self-expanding Evolut PRO (Medtronic, Minneapolis, Minnesota) valve failing to expand due to nitinol frame infolding. This results in a malopposed valve with a severe paravalvular leak, even though treated successfully with balloon valvuloplasty. It is important to recognize the characteristic angiographic signature of this complication-the "straight line" sign-and how to avoid this potentially serious complication by balloon valvuloplasty or by recapture and deployment of a new valve.

External Prosthetic Reinforcement of the Pulmonary Autograft.

BACKGROUND: Neo-aortic root dilatation accounts for the majority of reoperations needed after the Ross procedure with implantation of the pulmonary autograft as complete root replacement. This study evaluates early results of external prosthetic reinforcement of the autograft. METHODS: From July 2015 to October 2017, 16 adolescent and adult patients received a Ross procedure at our department by this technique. A congenital-dysplastic valve was present in 13 patients, including 9 patients with a bicuspid aortic valve. Clinical and echocardiographic follow-up is complete with a mean duration of 19.7 ± 5.8 months. RESULTS: The mean age at operation was 27.1 ± 16.1 years. Mean aortic cross-clamping time was 102 ± 39 minutes. No bleeding complication occurred. The median stay on the intensive care unit was 2 days. In-hospital mortality was 0%. All patients were discharged with no or trivial aortic regurgitation. In one patient both the autograft and homograft were replaced because of endocarditis 3 months after the primary operation, leading to 93.8% freedom from reoperation at 2 years. There were no late deaths during the study period. The latest echocardiography confirmed absence of aortic regurgitation grade >I in all patients. Neo-aortic root diameters remained stable during follow-up. CONCLUSION: The presented modification of the Ross procedure does not prolong ischemia time, and can be performed with a low operative morbidity and mortality and an excellent early valve function.

First North American experience with the transfemoral ACURATE-neoTM self-expanding transcatheter aortic bioprosthesis.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) has become a therapeutic alternative for patients presenting with severe symptomatic aortic stenosis and considered at high-surgical risk. Paravalvular leak (PVL), conduction disorders, and coronary obstruction remain unresolved procedure-related complications. The aim of this manuscript was to report the first North American experience with the ACURATE-neoTM aortic bioprosthesis and its ACURATE-TFTM delivery system (Symetis S.A., Ecublens, Switzerland). METHODS: Transfemoral ACURATE-neoTM aortic valve implantation was performed in 20 patients. Clinical and echocardiographic assessment was performed at baseline, postprocedure and at least 30 days. Outcomes were assessed according to valvular academic research consortium (VARC-2) criteria. RESULTS: The mean age was 82.7 ± 7.0 years with a mean logistic-EuroSCORE-II of 5.0 ± 2.9% and Society of Thoracic Surgeons score of 4.7 ± 2.3%. Device success was achieved in all patients. The mean distance between the aortic-annulus and the left main coronary artery ostium was 14.3 ± 3.2 mm, and eight (40%) patients had <12 mm. At 30 days, there were no deaths, conversions to surgery, or major procedure-related complications. New-pacemaker implantation was required in one (5.3%) patient. ACURATE-neoTM implantation resulted in a significant reduction in mean transvalvular gradient (49.9 ± 15.8 to 9.7 ± 5.7 mm Hg, P < 0.0001) and increase in effective-orifice area (0.65 ± 0.16 to 1.83 ± 0.36 cm2 , P = 0.001) at hospital discharge. Paravalvular leak was absent in four (20%) patients, trace in nine (45%) patients, and mild in seven (35%) patients. Hospital discharge occurred at a mean of 7.0 ± 4.5 days, and all patients were in NYHA class I-II at a mean follow-up of 8.6 ± 2.3 months. CONCLUSION: The present initial North American experience shows that the ACURATE-neoTM aortic bioprosthesis was safely and successfully implanted by transfemoral approach. The special design of this newer-generation device affords a stable and predictable implantation, while providing optimal hemodynamic performance with a relatively low rate of PPI. © 2016 Wiley Periodicals, Inc.

Percutaneous aortic valve closure for patients with left ventricular assist device-associated aortic insufficiency.

The development of de novo aortic insufficiency (AI) is a significant complication of long-term LVAD support, which can lead to ineffective support, decreased device durability, end organ malperfusion, and increased mortality. Surgical aortic valve (AV) closure has been the standard treatment for symptomatic patients, but is associated with high mortality and recurrence of AI. Percutaneous AV closure using the Amplatzer cribriform device is a feasible and may be the preferable option to treat LVAD-associated severe AI in high-surgical risk patients. Certain technical issues with this procedure should be taken into consideration to achieve optimal results. © 2015 Wiley Periodicals, Inc.

Valve-in-Valve Procedures in Failing Biological Xenografts Using a Novel Balloon-Expandable Device: Experience in Aortic, Mitral, and Tricuspid Positions.

Background Valve-in-valve (ViV) procedures for degenerated bioprostheses are an alternative for the standard of care in an aging population. Several reports showed that the Edwards Sapien XT (Edwards Lifesciences Co., Irvine, California, United States) transcatheter heart valve (THV) can be used in aortic, mitral, and tricuspid position for ViV procedures. No published case series for different valve positions exist regarding suitability of the new Edwards Sapien 3 (Edwards Lifesciences Co.) THV for this purpose. Especially, the increased stent height compared with the XT and the newly added polyethylene terephthalate cuff is of potential concern in ViV interventions. Herein, we report six cases of ViV procedures with the Edwards Sapien 3 THV with a focus on technical considerations. Methods and Results Between October 2013 and November 2014, six ViV procedures with the Edwards Sapien 3 THV were performed. Four implants were done in aortic, one in mitral, and one in tricuspid position. All procedures were performed successfully without any complications. Fluoroscopy and echocardiography confirmed an adequate position and function without any paravalvular or transvalvular leakage or elevated transvalvular gradients in any case. Conclusion Preliminary experience suggests, ViV procedures with the Edwards Sapien 3 THV are safe and reliable. The outer polyethylene terephthalate cuff, for enhanced paravalvular sealing, led to a good outcome, concerning PVL in ViV procedures without resulting in elevated transvalvular gradients. This was even the case in a mildly undersized THV when compared with the internal diameter of the surgical bioprosthesis. The central radiopaque positioning marker and the fine adjustment wheel allow for accurate positioning within degenerated bioprostheses. The increased stent height, compared with the Sapien XT, led to no complications, especially in mitral position. In bioprostheses without any fluoroscopic landmarks, a balloon valvuloplasty may be necessary to identify the appropriate deployment position.

Transcaval access for TAVR across a polyester aortic graft.

Transcaval access to the aorta allows transcatheter aortic valve replacement in patients without other good access options. The resulting aorto-caval fistula is closed with a nitinol cardiac occluder device. There is no experience traversing a synthetic aortic graft to perform transcaval access and closure. We describe a patient who underwent successful traversal of a polyester aortic graft using radiofrequency energy applied from the tip of a guidewire, to allow retrograde transcatheter aortic valve replacement from a femoral vein, along with details of our technique. The patient did well and was discharged home after 3 days. There was residual aorto-caval fistulous flow immediately after implantation of a polyester-seeded nitinol muscular ventricular septal defect occluder device, but this fistula spontaneously occluded within one month.

Decellularization and characterization of camel pericardium as a new scaffold for tissue engineering and regenerative medicine.

BACKGROUND: Valvular heart diseases (VHDs) have become prevalent in populations due to aging. Application of different biomaterials for cardiac valve regeneration and repair holds a great promise for treatment of VHD. Aortic valve replacement using tissue-engineered xenografts is a considered approach, and the pericardium of different species such as porcine and bovine has been studied over the last few years. It has been suggested that the animal origin can affect the outcomes of replacement. METHODS: So, herein, we at first decellularized and characterized the camel pericardium (dCP), then characterized dCP with H&E staining, in vitro and in vivo biocompatibility and mechanical tests and compared it with decellularized bovine pericardium (dBP), to describe the potency of dCP as a new xenograft and bio scaffold. RESULTS: The histological assays indicated less decluttering and extracellular matrix damage in dCP after decellularization compared to the dBP also dCP had higher Young Modulus (105.11), and yield stress (1.57 ± 0.45). We observed more blood vessels and also less inflammatory cells in the dCP sections after implantation. CONCLUSIONS: In conclusion, the results of this study showed that the dCP has good capabilities not only for use in VHD treatment but also for other applications in tissue engineering and regenerative medicine.

Mid-term follow up of a novel bioprosthesis in aortic valve surgery.

BACKGROUND AND AIM OF THE STUDY: The BioPhysio bioprosthesis (Edwards Lifesciences LLC, Irvine, CA, USA) was designed to further improve the hemodynamic performance currently achieved by stented valves. A flexible Nitinol stent that preserves aortic root dynamics, thus maximizing the effective orifice area (EOA), is a key innovation of this prosthesis. The study aim was to provide a clinical evaluation of this new device. METHODS: Between December 2004 and August 2005, a total of 50 patients (27 males, 23 females; mean age 75.8 +/- 5.1 years; range: 55-84 years) received a BioPhysio aortic bioprosthesis. Clinical outcomes, EOAs, mean gradients and regression of left ventricular hypertrophy were evaluated echocardiographically at discharge, and at six, 12, 24, 36, 48, and 60 months after surgery. RESULTS: The 60-month follow up was complete for all patients. No patients died within 30 days of surgery, but the late mortality was 14% (n = 6). There was one sudden unexplained death. One patient developed endocarditis at two years after surgery and underwent reoperation. There were no cases of stroke or renal failure. The BioPhysio prosthesis showed a good hemodynamic performance, with a significant fall in mean gradient to 15.1 +/- 8.3 mmHg, a mean EOA of 1.5 +/- 0.7 cm2, and a mean ejection fraction of 61 +/- 7.2%. There were no cases of aortic regurgitation. The NYHA functional class was improved in all patients, and there was a significant reduction in the left ventricular mass index to 185.7 +/- 49.6 g/m2 at 24 months. CONCLUSION: The clinical performance of the BioPhysio aortic bioprosthesis is comparable to that of regular stentless aortic valves. However, clinical approval for the widespread use of this bioprosthesis was not obtained.

Membrane sealant Poloxamer P188 protects against isoproterenol induced cardiomyopathy in dystrophin deficient mice.

BACKGROUND: Cardiomyopathy in Duchenne muscular dystrophy (DMD) is an increasing cause of death in patients. The absence of dystrophin leads to loss of membrane integrity, cell death and fibrosis in cardiac muscle. Treatment of cardiomyocyte membrane instability could help prevent cardiomyopathy. METHODS: Three month old female mdx mice were exposed to the ß(1) receptor agonist isoproterenol subcutaneously and treated with the non-ionic tri-block copolymer Poloxamer P188 (P188) (460 mg/kg/dose i.p. daily). Cardiac function was assessed using high frequency echocardiography. Tissue was evaluated with Evans Blue Dye (EBD) and picrosirius red staining. RESULTS: BL10 control mice tolerated 30 mg/kg/day of isoproterenol for 4 weeks while death occurred in mdx mice at 30, 15, 10, 5 and 1 mg/kg/day within 24 hours. Mdx mice tolerated a low dose of 0.5 mg/kg/day. Isoproterenol exposed mdx mice showed significantly increased heart rates (p < 0.02) and cardiac fibrosis (p < 0.01) over 4 weeks compared to unexposed controls. P188 treatment of mdx mice significantly increased heart rate (median 593 vs. 667 bpm; p < 0.001) after 2 weeks and prevented a decrease in cardiac function in isoproterenol exposed mice (Shortening Fraction = 46 ± 6% vs. 35 ± 6%; p = 0.007) after 4 weeks. P188 treated mdx mice did not show significant differences in cardiac fibrosis, but demonstrated significantly increased EBD positive fibers. CONCLUSIONS: This model suggests that chronic intermittent intraperitoneal P188 treatment can prevent isoproterenol induced cardiomyopathy in dystrophin deficient mdx mice.

How yarn orientation limits fibrotic tissue ingrowth in a woven polyester heart valve scaffold: a case report.

Transcatheter Aortic Valve Implantation (TAVI) has become today a popular alternative technique to surgical valve replacement for critical patients. However, with only six years follow up on average, little is known about the long-term durability of transcatheter implanted biological tissue. Moreover, the high cost of tissue harvesting and chemical treatment procedures favor the development of alternative synthetic valve leaflet materials. In that context, thin, strong and flexible woven fibrous constructions could be considered as interesting candidates. However, the interaction of textile material with living tissue should be comparable to biological tissue, and the Foreign Body Reaction (FBR) in particular should be controlled. Actually, the porosity of textile materials tends to induce exaggerated tissue ingrowth which may prevent the implants from remaining flexible. The purpose of this preliminary animal case study is to investigate the influence of the valve leaflet yarn orientation on the fibrotic tissue ingrowth. For that purpose the in vivo performances of 45° inclined yarn woven valve leaflets implanted in juvenile sheep model were assessed after three months implantation. Results bring out that in the frame of this case study the development of fibrosis is limited with a woven fabric valve obtained from 45° inclined yarns.

Heart valves from polymeric fibers: potential and limits.

Transcatheter aortic valve implantation (TAVI) has become today a popular alternative technique to surgical valve replacement for critical patients. However, with only six years follow-up on average, little is known about the long-term durability of transcatheter implanted biological tissue. Moreover, the high cost of biological tissue harvesting and chemical treatment procedures favor the development of alternative synthetic valve leaflet materials. In that context, thin, flexible and porous textile constructions could be considered as interesting candidates. However, these constructions must be strong enough to withstand the load applied on the leaflet especially in aortic position. Moreover, the interaction of textile material with living tissue should be comparable to biological valve tissue, and the foreign body reaction (FBR) as well as the calcification mechanisms should be controlled. In the frame of heart valve tissue engineering strategies, the use of bioresorbable polymer scaffolds is expected to limit that FBR. However, to precisely control the degradation of the polymer is not trivial. Conversely, when permanent textile polymers are considered, the porosity of the fibrous scaffold tends to induce exaggerated tissue ingrowth which may prevent the implants from remaining flexible. In that context, the ideal synthetic fibrous valve leaflet remains to be found. The purpose of this study was to investigate the possible strategies which have been adopted over the last 50 years regarding the use of textile as heart valve leaflet material. Results showed that textile presented potential, despite remaining strong challenges. It came out that hybrid textiles combining bioresorbable and permanent polymer fibers arranged in both non-woven and woven or knitted way could probably help providing strength and generating appropriate tissue ingrowth.

Experimental evaluation of the JenaClip transcatheter aortic valve.

OBJECTIVE: Transcatheter techniques of aortic valve replacement are a treatment option for valvular heart disease in high-risk surgical candidates. We evaluated a self-expanding valve system with a novel mechanism of fixation in an experimental setting in an acute animal model and ex vivo in aortic root specimens. METHOD: A self-expanding nitinol stent containing a pericardial tissue valve was implanted in a transapical approach in 15 sheeps. The valve was introduced under fluoroscopic guidance through a 22F sheath by means of a specially designed delivery catheter. Deployment was performed on the beating heart without cardiopulmonary bypass or rapid ventricular pacing and facilitated by positioning feelers anchoring the device to the native aortic cusps. To investigate release and anchoring of the device during retrograde implantation, the stent was also implanted in aortic root specimens obtained from an autopsy series. RESULTS: In animal experiments, stent deployment was primarily successful in 12 (80%) animals. Positioning feelers facilitated implantation by confirming the correct implantation plane of the stent and anchoring to the native aortic cusps. If primary location was not satisfactory the stent was retracted into the catheter and repositioned. After successful implantation no significant changes of hemodynamics were observed. Two animals (13%) developed ventricular fibrillation early in this experimental series due to displacement of one positioning element into a coronary ostium, major regurgitation was observed in two animals. Ex vivo evaluation of the device in aortic root specimens proved feasibility of stent release and leaflet fixation; ex vivo implantation was successful in all cases. CONCLUSION: In this study, we demonstrate feasibility of a leaflet-fixation device in nondiseased aortic valves. The JenaClip provides an effective concept of fixation with positioning feelers that allows exact positioning without outflow obstruction and anchoring the valve to the native leaflets. Further studies are necessary to investigate this concept in diseased aortic valves.

The development of 3-D, in vitro, endothelial culture models for the study of coronary artery disease.

The response of the vascular endothelium to wall shear stress plays a central role in the development and progression of atherosclerosis. Current studies have investigated endothelial response using idealized in vitro flow chambers. Such cell culture models are unable to accurately replicate the complex in vivo wall shear stress patterns arising from anatomical geometries. To better understand this implication, we have created both simplified/tubular and anatomically realistic in vitro endothelial flow models of the human right coronary artery. A post-mortem vascular cast of the human left ventricular outflow tract was used to create geometrically accurate silicone elastomer models. Straight, tubular models were created using a custom made mold. Following the culture of human abdominal aortic endothelial cells within the inner lumen, cells were exposed to steady flow (Re = 233) for varying time periods. The resulting cell morphology was analyzed in terms of shape index and angle of orientation relative to the flow direction. In both models a progressive elongation and alignment of the endothelium in the flow direction was observed following 8, 12, and 24 hours. This change, however, was significantly less pronounced in the anatomical model (as observed from morphological variations indicative of localized flow features). Differences were also observed between the inner and outer walls at the disease-prone proximal region. Since morphological adaptation is a visual indication of endothelial shear stress activation, the use of anatomical models in endothelial genetic and biochemical studies may offer better insight into the disease process.

The Fate of Transcaval Access Tracts: 12-Month Results of the Prospective NHLBI Transcaval Transcatheter Aortic Valve Replacement Study.

OBJECTIVES: The authors investigated 1-year outcomes after transcaval access and closure for transcatheter aortic valve replacement (TAVR), using commercially available nitinol cardiac occluders off-label. BACKGROUND: Transcaval access is a fully percutaneous nonfemoral artery route for TAVR. The intermediate-term fate of transcaval access tracts is not known. METHODS: The authors performed a prospective, multicenter, independently adjudicated trial of transcaval access, using Amplatzer nitinol cardiac occluders (Abbott Vascular, Minneapolis, Minnesota), among subjects without traditional transthoracic (transapical or transaortic) access options. One-year clinical follow-up included core laboratory analysis of serial abdominal computed tomography (CT). RESULTS: 100 subjects were enrolled. Twelve-month mortality was 29%. After discharge, there were no vascular complications of transcaval access. Among 83 evaluable CT scans after 12 months, 77 of fistulas (93%) were proven occluded, and only 1 was proven patent. Fistula patency was not associated with overall survival (p = 0.37), nor with heart failure admissions (15% if patent vs. 23% if occluded; p = 0.30). There were no cases of occluder fracture or migration or visceral injury. CONCLUSIONS: Results are reassuring 1 year after transcaval TAVR and closure using permeable nitinol occluders off-label. There were no late major vascular complications. CT demonstrated spontaneous closure of almost all fistulas. Results may be different in a lower-risk cohort, with increased operator experience, and using a dedicated transcaval closure device. (Transcaval Access for Transcatheter Aortic Valve Replacement in People With No Good Options for Aortic Access; NCT02280824).

Computational methods for the aortic heart valve and its replacements.

INTRODUCTION: Replacement with a prosthetic device remains a major treatment option for the patients suffering from heart valve disease, with prevalence growing resulting from an ageing population. While the most popular replacement heart valve continues to be the bioprosthetic heart valve (BHV), its durability remains limited. There is thus a continued need to develop a general understanding of the underlying mechanisms limiting BHV durability to facilitate development of a more durable prosthesis. In this regard, computational models can play a pivotal role as they can evaluate our understanding of the underlying mechanisms and be used to optimize designs that may not always be intuitive. Areas covered: This review covers recent progress in computational models for the simulation of BHV, with a focus on aortic valve (AV) replacement. Recent contributions in valve geometry, leaflet material models, novel methods for numerical simulation, and applications to BHV optimization are discussed. This information should serve not only to infer reliable and dependable BHV function, but also to establish guidelines and insight for the design of future prosthetic valves by analyzing the influence of design, hemodynamics and tissue mechanics. Expert commentary: The paradigm of predictive modeling of heart valve prosthesis are becoming a reality which can simultaneously improve clinical outcomes and reduce costs. It can also lead to patient-specific valve design.

In Vitro Hydrodynamic Assessment of a New Transcatheter Heart Valve Concept (the TRISKELE).

This study presents the in vitro hydrodynamic assessment of the TRISKELE, a new system suitable for transcatheter aortic valve implantation (TAVI), aiming to mitigate the procedural challenges experienced with current technologies. The TRISKELE valve comprises three polymeric leaflet and an adaptive sealing cuff, supported by a novel fully retrievable self-expanding nitinol wire frame. Valve prototypes were manufactured in three sizes of 23, 26, and 29 mm by automated dip-coating of a biostable polymer, and tested in a hydrodynamic bench setup in mock aortic roots of 21, 23, 25, and 27 mm annulus, and compared to two reference valves suitable for equivalent implantation ranges: Edwards SAPIEN XT and Medtronic CoreValve. The TRISKELE valves demonstrated a global hydrodynamic performance comparable or superior to the controls with significant reduction in paravalvular leakage. The TRISKELE valve exhibits enhanced anchoring and improved sealing. The valve is currently under preclinical investigation.

Remodeling root repair with an external aortic ring annuloplasty.

OBJECTIVE: Although the remodeling technique provides the most dynamic valve-sparing root replacement, a dilated annulus (>25 mm) is a risk factor for failure. Aortic annuloplasty aims to reduce the annulus diameter, thus increasing coaptation height to protect the repair. The results of 177 patients with remodeling and external aortic ring annuloplasty were studied. METHODS: Data were collected from the Aortic Valve repair InternATiOnal Registry. Preoperative aortic insufficiency grade 3 or greater was present in 79 patients (44.7%). The valve was bicuspid in 59 patients (33.3%). External annuloplasty was performed through a homemade Dacron ring (56) or a dedicated expansible aortic ring (121). RESULTS: Thirty-day mortality was 2.9% (5). Mean follow-up was 41.1 ± 36.4 months. For the whole series, freedom from valve-related reoperation, aortic insufficiency grade 3 or greater, aortic insufficiency grade 2 or greater, and major adverse valve-related events were 89.5%, 90.5%, 77.4%, and 86.6% at 7 years, respectively, with similar results for tricuspid and bicuspid valves. Since 2007, systematic use of calibrated expansible ring annuloplasty, followed 1 year later by systematic cusp effective height assessment, significantly increased 7-year freedom from valve-related reoperation, aortic insufficiency grade 3 or greater, and major adverse valve-related events up to 99.1% ± 0.9% (P = .017), 100% (P = .026), and 96.3% ± 1.8% (P = .035), respectively, whereas freedom from aortic insufficiency grade 2 or greater remained unaffected (78.1% ± 7.6%). Calibrated annuloplasty and effective height assessment were identified as protective factors from reoperation: hazard ratio, 0.13; 95% confidence interval, 0.02-1.06; P = .057 and hazard ratio, 0.11; 95% confidence interval, 0.01-0.95; P = .044, respectively. CONCLUSIONS: The standardization of remodeling root repair with calibrated expansible aortic ring annuloplasty and cusp effective height assessment improves valve repair outcomes.

Geometric modeling of functional trileaflet aortic valves: development and clinical applications.

The dimensions of the aortic valve components condition its ability to prevent blood from flowing back into the heart. While the theoretical parameters for best trileaflet valve performance have already been established, an effective approach to describe other less optimal, but functional models has been lacking. Our goal was to establish a method to determine by how much the dimensions of the aortic valve components can vary while still maintaining proper function. Measurements were made on silicone rubber casts of human aortic valves to document the range of dimensional variability encountered in normal adult valves. Analytical equations were written to describe a fully three-dimensional geometric model of a trileaflet valve in both the open and closed positions. A complete set of analytical, numerical and graphical tools was developed to explore a range of component dimensions within functional aortic valves. A list of geometric guidelines was established to ensure safe operation of the valve during the cardiac cycle, with practical safety margins. The geometry-based model presented here allows determining quickly if a certain set of valve component dimensions results in a functional valve. This is of great interest to designers of new prosthetic heart valve models, as well as to surgeons involved in valve-sparing surgery.

North American single-center experience with a sutureless aortic bioprosthesis.

OBJECTIVE: Surgical sutureless aortic valves have the potential for shorter procedural times and could benefit patients with increased risk. The Enable (Medtronic Inc, Minneapolis, Minn) valve is a bioprosthesis housed in a Nitinol cage allowing folding and deployment once implanted. We aimed to evaluate the early clinical and echocardiographic results with the Enable valve. METHODS: Patients with aortic stenosis, Society of Thoracic Surgeons score greater than 5.0%, the need for combined procedures, and frailty were considered for Enable implantation. RESULTS: Between August 2012 and October 2014, 63 patients underwent implantation of the Enable valve (Medtronic Inc, Minneapolis, Minn). Thirty patients underwent isolated aortic valve replacement. Combined procedures were aortic valve replacement/coronary artery bypass grafting (26), aortic valve replacement/mitral valve repair (2), aortic valve replacement/mitral valve repair/coronary artery bypass grafting (2), and aortic valve replacement/ascending aortic graft (3). Predicted Society of Thoracic Surgeons score was 8.06 ± 7.73 (0.94-41.30). Implant success was 100%. Mean crossclamp time for isolated aortic valve replacement was 44 ± 14 minutes (30-91). Thirty-day mortality was 1.6% (1/63), and late mortality was 3.2% (2/62). No mortality was valve related. Intraoperative need for revision was 6.3% (4/63). Early migration requiring reoperation occurred in 1.6% of patients (1/63). Postoperative indexed aortic valve area was 1.08 ± 0.22 cm(2)/m(2), and peak and mean gradients were 17 ± 7 mm Hg and 9 ± 4 mm Hg, respectively. The rate of complications was as follows: pacemaker 3.1% (2/63), transient ischemic attack 1.6% (1/63), other thromboembolic events 0%, bleeding 0%, and endocarditis 0%. Mean follow-up was 10 ± 8 months. At latest follow-up, 61 patients were in New York Heart Association class I. Moderate or severe aortic regurgitation did not develop in any patients in the follow-up period. CONCLUSIONS: The Enable bioprosthesis is an acceptable alternative to conventional aortic valve replacement in higher-risk patients. The early hemodynamic performance seems favorable.