Virtual Valve Research Articles

3-Dimensional Echocardiographic Prediction of Left Ventricular Outflow Tract Area Prior to Transcatheter Mitral Valve Replacement

BackgroundNew postprocessing software facilitates 3-dimensional (3D) echocardiographic determination of mitral annular (MA) and neo–left ventricular outflow tract (neo-LVOT) dimensions in patients undergoing transcatheter mitral valve replacement (TMVR). ObjectivesThis study aims to test the accuracy of 3D echocardiographic analysis as compared to baseline computed tomography (CT). MethodsA total of 105 consecutive patients who underwent TMVR at 2 tertiary care centers between October 2017 and May 2023 were retrospectively included. A virtual valve was projected in both baseline CT and 3D transesophageal echocardiography (TEE) using dedicated software. MA dimensions were measured in baseline images and neo-LVOT dimensions were measured in baseline and postprocedural images. All measurements were compared to baseline CT as a reference. The predicted neo-LVOT area was correlated with postprocedural peak LVOT gradients. ResultsThere was no significant bias in baseline neo-LVOT prediction between both imaging modalities. TEE significantly underestimated MA area, perimeter, and medial-lateral dimension compared to CT. Both modalities significantly underestimated the actual neo-LVOT area (mean bias pre/post TEE: 25.6 mm2, limit of agreement: −92.2 mm2 to 143.3 mm2; P < 0.001; mean bias pre/post CT: 28.3 mm2, limit of agreement: −65.8 mm2 to 122.4 mm2; P = 0.046), driven by neo-LVOT underestimation in the group treated with dedicated mitral valve bioprosthesis. Both CT- and TEE-predicted-neo-LVOT areas exhibited an inverse correlation with postprocedural LVOT gradients (r2 = 0.481; P < 0.001 for TEE and r2 = 0.401; P < 0.001 for CT). ConclusionsTEE-derived analysis provides comparable results with CT-derived metrics in predicting the neo-LVOT area and peak gradient after TMVR.

4-Dimensional Right Ventricular Outflow Tract Segmentation to Evaluate Candidacy for Transcatheter Pulmonary Valve Replacement.

Candidacy for transcatheter pulmonary valve replacement utilizing newer valve platforms is aided by industry-driven fit analyses. We report augmentation of this decision-making process by visualization of 4-dimensional cine imaging of patient-specific right ventricular outflow tract anatomy and a virtual valve model within a virtual reality platform.

Commissural vs Coronary Alignment to Avoid Coronary Overlap With THV-Commissure in TAVR: A CT-Simulation Study

BackgroundCoronary alignment is proposed as an alternative to commissural alignment for reducing coronary overlap during transcatheter aortic valve replacement (TAVR). However, largescale studies are lacking. ObjectivesThis study aimed to determine the incidence of coronary overlap with commissural vs coronary alignment using computed tomography (CT) simulation in patients undergoing TAVR evaluation. MethodsIn 1,851 CT scans of native aortic stenosis patients undergoing TAVR evaluation (April 2018 to December 2022),virtual valves simulating commissural and coronary alignment were superimposed on axial aortic root images. Coronary overlap was assessed based on the angular gap between coronary artery origin and the nearest transcatheter heart valve commissure, categorized as severe (≤15°), moderate (15°-30°), mild (30°-45°), and no-overlap (45°-60°). ResultsThe overall incidence of moderate/severe and severe overlap with either coronary artery remained rare with either coronary or commissural alignment (coronary 0.52% left, 0.52% right; commissural 0.30% left, 3.27% right). Comparing techniques, coronary alignment reduced moderate/severe overlap only for the right coronary artery (0.38% vs 2.97%; P <0.0001). For the left coronary artery, both techniques showed similar moderate/severe overlap, but commissural alignment had significantly higher no-overlap rates (91.1% vs 84.9%; P < 0.0001). Fluoroscopic angle during valve deployment was strongly correlated between commissural and coronary alignment (r = 0.80; P < 0.001). ConclusionsUsing CT simulation, the incidence of coronary overlap with transcatheter heart valve-commissure is rare with commissural alignment. Coronary alignment reduced right coronary overlap, whereas commissural alignment had higher rates of no left coronary overlap. Coronary alignment should be reserved only when commissural alignment results in severe coronary overlap.

Standardization and validation of neoLVOT assessment using three-dimensional trans-esophageal echocardiography before trans-catheter mitral valve replacement.

Trans-catheter mitral valve replacement (TMVR) procedures had emerged as an alternative solution for patients who are at high risk for mitral valve surgery. Although cardiac computed tomography (CT) remains the standard method for procedural planning, there is no full agreement on the best systolic phase for quantitation of the neoLVOT. Furthermore, a new three-dimensional trans-esophageal echocardiography (3DTEE) based software was developed to serve as filter and or an alternative for patients who cannot have CT due to any contraindication. To determine the systolic phase of the cardiac cycle that shows the narrowest NeoLVOT area in order to standardize the way of using these software and then to validate the 3DTEE-based software against the CT-based one as a gold standard, in mitral valve annulus (MA) and NeoLVOT assessment. A single center, observational, retrospective study. Initially, a sample of 20 patients (age 62±4 years, 70% men) had CT-based analysis at mid-diastole (80%), early-systole (10%), mid-systole (20%), late-systole (30%-40%), in order to detect the best systolic phase at which the neoLVOT area is the narrowest after TMVR. Then, the end systolic phase was standardized for the analysis of 49 patients (age 57±6 years, 60% men), using both the commercially available CT-based software and the newly available 3DTEE-based software (3mensio Structural Heart, Pie Medical Imaging, The Netherlands). The 3DTEE derived parameters were compared with the gold standard CT-based measurements. The neoLVOT area was significantly narrower at end-systole (224±62 mm2), compared to early-systole (299±70 mm2) and mid-systole (261±75 mm2), (p=.005). Excellent correlation was found between 3DTEE and CT measurements for MA AP diameter (r=.96), IC diameter (r=.92), MA area (r=.96), MA perimeter (r=.94) and NeoLVOT area (r=.96), (all p-values<.0001). Virtual valve sizing was based on annulus measurement and was identical between CT and 3DTEE. Interobserver and intraobserver agreements were excellent for all the measurements with ICCs>.80. End-systole is the phase that shows the narrowest neoLVOT and hence should be the standard phase used during the analysis. The 3DTEE based analysis using this new software is reliable compared to the CT-based analysis and can be serve as an alternative analysis tool in patients who cannot have CT for any clinical contraindication or as a screening test and/or filter for all patients before proceeding to a detailed CT scan.

The feasibility of relaxation-enhanced angiography without contrast and triggering for preprocedural planning of transcatheter aortic valve implantation.

Cardiovascular MRI is advantageous in transcatheter aortic valve implantation (TAVI) planning. This study aimed to evaluate the feasibility of comprehensive non-contrast MRI [relaxation-enhanced angiography without contrast and triggering (REACT)] combined with a three-dimensional whole-heart MRI protocol for preprocedural planning of TAVI vs. computed tomography angiography (CTA). Thirty patients with severe aortic stenosis were prospectively enrolled. The anatomical properties of the aortic root anatomy, including the perimeter and area of the virtual aortic valve annulus and coronary heights, were determined from 3D whole-heart MRI and cardiac CTA (CCTA) images, respectively. The diameters of the aorta (thoracic and abdominal aorta) and iliofemoral arteries were measured from REACT and aortic CTA (ACTA) images, respectively. A paired t-test was used to compare these two modalities. Bland-Altman plots were used to assess cardiovascular MRI and CTA measurements. Transcatheter heart valve (THV) sizing was performed based on CCTA measurements and compared with 3D whole-heart MRI measurements. The extent of annular calcification on 3D whole-heart MRI images was evaluated by a four-point grading scale and compared with CCTA data. All 30 patients completed CTA and cardiovascular MRI examinations, with the TAVI procedure being administered in 25 patients. The mean acquisition time of the comprehensive MRI protocol was 18 ± 3.2 min. There were no significant differences between ACTA and REACT data in regard to the diameters of aortic and iliofemoral arteries, including the ascending thoracic aorta (37 ± 4.6 mm vs. 37.7 ± 5.2 mm, p = 0.085), descending thoracic aorta (24.3 ± 2.8 mm vs. 24.3 ± 2.8 mm, p = 0.832), abdominal aorta (20.9 ± 2.5 mm vs. 20.8 ± 2.5 mm, p = 0.602), bilateral common iliac arteries (right: 8.36 ± 1.44 mm vs. 8.42 ± 1.27 mm, p = 0.590; left: 8.61 ± 1.71 mm vs. 8.86 ± 1.46 mm, p = 0.050), and bilateral femoral arteries (right: 6.77 ± 1.06 mm vs. 6.87 ± 1.00 mm, p = 0.157; left: 6.75 ± 1.02 mm vs. 6.90 ± 0.80 mm, p = 0.142). Both modalities showed similar aortic valve morphology and semi-quantitative valve calcification (all, p's > 0.05). Overall agreement for implanted THV was found in all 25 (100%) patients assessed with both modalities. REACT combined with 3D whole-heart MRI enables reliable measurements of aortic root anatomy, annular calcification, and aorta and iliofemoral access in patients under evaluation for TAVI.

Feasibility of Coronary Access Following Redo-TAVR for Evolut Failure: A Computed Tomography Simulation Study.

Coronary accessibility following redo-transcatheter aortic valve replacement (redo-TAVR) is increasingly important, particularly in younger low-risk patients. This study aimed to predict coronary accessibility after simulated Sapien-3 balloon-expandable valve implantation within an Evolut supra-annular, self-expanding valve using pre-TAVR computed tomography (CT) imaging. A total of 219 pre-TAVR CT scans from the Evolut Low-Risk CT substudy were analyzed. Virtual Evolut and Sapien-3 valves were sized using CT-based diameters. Two initial Evolut implant depths were analyzed, 3 and 5 mm. Coronary accessibility was evaluated for 2 Sapien-3 in Evolut implant positions: Sapien-3 outflow at Evolut node 4 and Evolut node 5. With a 3-mm initial Evolut implant depth, suitable coronary access was predicted in 84% of patients with the Sapien-3 outflow at Evolut node 4, and in 31% of cases with the Sapien-3 outflow at Evolut node 5 (P<0.001). Coronary accessibility improved with a 5-mm Evolut implant depth: 97% at node 4 and 65% at node 5 (P<0.001). When comparing 3- to 5-mm Evolut implant depth, sinus sequestration was the lowest with Sapien-3 outflow at Evolut node 4 (13% versus 2%; P<0.001), and the highest at Evolut node 5 (61% versus 32%; P<0.001). Coronary accessibility after Sapien-3 in Evolut redo-TAVR relates to the initial Evolut implant depth, the Sapien-3 outflow position within the Evolut, and the native annular anatomy. This CT-based quantitative analysis may provide useful information to inform and refine individualized preprocedural CT planning of the initial TAVR and guide lifetime management for future coronary access after redo-TAVR. URL: https://www.clinicaltrials.gov; Unique identifier: NCT02701283.

Preemptive alcohol septal ablation prior to transcatheter mitral valve replacement.

Alcohol septal ablation (ASA) has been shown to increase the neo-left ventricular outflow tract (LVOT) area before transcatheter mitral valve replacement (TMVR) but there is little literature on its success and use with dedicated devices. To describe our experience with preemptive ASA to increase the predicted neo-LVOT area and its utility with both dedicated TMVR devices and balloon-expandable valves. All patients who underwent ASA for TMVR candidacy in our center between May 2018 and October 2022 and had computed tomography(CT) scans done before and after ASA were included. Each CT was assessed for the minimum predicted neo-LVOT area at end-systole, using a virtual valve of the desired TMVR device for each patient. The primary outcome was an increase in the predicted neo-LVOT area after ASA that was deemed sufficient for safe implantation of the desired TMVR device. The secondary outcome was the absence of acute LVOT obstruction after TMVR. A total of 12 patients underwent ASA and all but 1 (n = 11, 91.6%) achieved the primary outcome of having sufficient predicted neo-LVOT area to proceed with TMVR. The mean increase in neo-LVOT area after ASA was 126 ± 64 mm2 (median 119.5, interquartile range: 65.0-163.5 mm2 ). Two patients (16.7%) required a permanent pacemaker after ASA. Nine patients went on and underwent TMVR with their respective devices and none had LVOT obstruction after the procedure. Among the remaining three patients, one had insufficient neo-LVOT clearance after ASA, one had unrelated mortality before TMVR, and one had advanced heart failure before TMVR. In appropriately selected patients and at centers experienced with ASA, preemptive ASA can achieve sufficient neo-LVOT clearance for TMVR with a variety of devices in approximately 90% of patients.

TCT-138 The Impact of Calcified Raphe on Transcatheter Valve Position in Bicuspid Patients: Implications for Redo-TAVR Feasibility and Virtual Valve Planning

TCT-138 The Impact of Calcified Raphe on Transcatheter Valve Position in Bicuspid Patients: Implications for Redo-TAVR Feasibility and Virtual Valve Planning

Timing of the narrowest neoLVOT with trans-catheter mitral valve implantation, a cardiac computed tomography study

Abstract Funding Acknowledgements Type of funding sources: None. Background Trans-catheter mitral valve replacement (TMVR) procedures had emerged as an alternative solution for patients who have surgical high risk for mitral valve surgery. One of the main challenges faced during the percutaneous approach is the degree of left ventricular outflow tract (LVOT) narrowing after implanting the new percutaneous mitral prosthesis. The remaining LVOT area (NeoLVOT) can be estimated by a commercially available CT analysis software that allows the insertion of a virtual valve within the CT dataset in the native annulus and/or the degenerated bioproshesis and hence allows measurement of the NeoLVOT using the multi-planar reconstruction (MPR) mode. The systolic phase that shows the narrowest NeoLVOT is not fully understood, and hence there is a considerable variability between operators in choosing the best phase in systole at which they should insert the virtual valve within the mitral annulus in the CT dataset to measure the narrowest NeoLVOT. Purpose To detect the systolic phase that shows the narrowest NeoLVOT and hence standardize the way to use the software to decrease variability among operators. Methods A retrospective observational single center study, including 20 patients (age 62± 4 years, 70% men), who had undergone a clinically indicated cardiac computed tomography (CT). All these patients were in sinus rhythm, had no significant coronary artery disease bases on CT report, and had normal left ventricular systolic function with no regional wall motion abnormalities, we excluded patients who had previous cardiac surgeries, hypertrophic cardiomyopathy, significant pulmonary hypertension or congenital heart disease that may affect septal motion. CTs were performed using a 128 slice dual-source (Somatom Definition Flash, Siemens Healthineers, Erlangen, Germany) with a retrospective ECG-gated acquisition CT analysis was done by a single operator using the commercially available software (3mensio Structural Heart 10.3, Pie Medical Imaging, The Netherlands). Multiphase scans were used and mid-diastole (80%), early-systole (10%), mid-systole (20%), late-systole (30–40%) were identified and analysed. Measurements done were; mitral annulus (MA) antero-posterior (AP) diameter, inter-commissural (IC) diameter, annulus area (Area), annulus perimeter (Peri), aorto-mitral angel, and the NeoLVOT area. (Figure 1). Results All measurements were feasible in all phases for all patients. The neoLVOT area was significantly narrower at end-systole (224 ± 62mm²), compared to early-systole (299 ± 70mm²) &amp; mid-systole (261 ± 75 mm²), (p = 0.005). All other measurement did not show statistically significant changes despite taking certain trends. (Figure 2). Conclusions End-systole is the cardiac phase that shows the narrowest predicted Neo-LVOT area and hence it should be the standard phase to be used during CT analysis before TMVR to predict the narrowest NeoLVOT.

Validation of a three-dimensional trans-esophageal echocardiography analysis software to assess mitral valve annulus and predicted Neo-LVOT before trans-catheter mitral valve replacement

Abstract Funding Acknowledgements Type of funding sources: None. Background Trans-catheter mitral valve replacement (TMVR) procedures had emerged as an alternative solution for patients who have surgical high risk for mitral valve surgery. One of the main challenges faced during the percutaneous approach is the degree of left ventricular outflow tract (LVOT) narrowing after implanting the new percutaneous mitral prosthesis. The remaining LVOT area (NeoLVOT) can be estimated by a commercially available CT analysis software that allows the insertion of a virtual valve within the CT dataset in the native annulus and/or the degenerated bioproshesis and hence allows measurement of the NeoLVOT using the multi-planar reconstruction (MPR) mode. Due to the radiation as well as intravenous contrast risk of the CT scans, a new 3DTEE based software was developed, using the same concept of the virtual valve implantation within the 3DTEE dataset to measure the NeoLVOT using the MPR mode. Using this 3DTEE based software avoids the risks associated with CT (radiation &amp; contrast) and can be a reasonable alternative for patients with impaired renal function or a screening test and/or filter for all patients before proceeding to a detailed CT scan if found suitable based on the 3DTEE analysis. Purpose To validate the 3DTEE based software in mitral valve annulus (MA) and NeoLVOT assessment using the CT based software as a gold standard. Methods A retrospective observational single center study, including 49 patients (age 57± 6 years, 60% men), who had undergone Cardiac computed tomography (CT) and three-dimensional trans-esophageal echocardiography (3DTEE) within one month from each other for any clinical indication. We excluded patients who had previous mitral or aortic valve surgeries. CT analysis was done using the commercially available software, (3mensio Structural Heart, Pie Medical Imaging, The Netherlands). 3DTEE analysis was done using the newly available software (3mensio Structural Heart 10.1–3mSH, Pie Medical Imaging, Bilthoven, Netherlands) Figure 1 Measurements done on both software were; mitral annulus (MA) antero-posterior (AP) diameter, inter-commissural (IC) diameter, annulus area (Area), annulus perimeter (Peri) and the NeoLVOT. Excellent correlation was found between 3D-TEE and CT measurements for MA AP diameter (r= 0.96), IC diameter (r=0.92), MA area (r =0.96), MA perimeter (r= 0.94) and NeoLVOT area (r= 0.96), (all P-values &amp;lt;0.0001). Virtual valve sizing was based on annulus measurement and was identical between CT and 3DTEE. Interobserver and intraobserver agreements were excellent for all the measurements with ICCs &amp;gt;0.80. Figure2 Conclusions Mitral annulus dimensions and Neo-LVOT assessment using this 3DTEE based analysis software is feasible and reliable compared to CT analysis. This can offer a good screening test or a filter for TMVR candidates and can also be a good alternative for patients who have a contraindication for CT.

Aortic root geometry following composite valve graft implantation: Implications for future valve-in-valve procedures

ObjectivesBiological composite valve grafts (CVGs) are being performed more frequently, which increases the need for interventions treating bioprosthetic valve failure. The feasibility of valve-in-valve procedures in this population is uncertain. This study aimed to assess changes in aortic root geometry and coronary height following CVG implantation to better understand future interventions. MethodsWe retrospectively identified 64 patients following bioprosthetic CVG replacement with pre- and postoperative computed tomography angiography. Root assessment was conducted as in preprocedural transcatheter aortic valve evaluation using a virtual valve simulation. ResultsIn 64 patients (age, 67.6 ± 9.3 years; 76.6% men) the preoperative coronary height was 14.3 ± 6.8 mm for the left coronary artery (LCA) and 17.9 ± 5.9 mm for the right coronary artery (RCA), which significantly decreased after CVG implantation, with 8.7 ± 4.4 mm for the LCA and 11.3 ± 4.4 mm for the RCA (P < .001). The virtual valve-to-coronary distances measured 4.0 ± 1.3 mm (LCA) and 4.6 ± 1.4 mm (RCA). Overall, 59.4% (n = 38) of patients with bio-CVGs would have been at risk for coronary obstruction, 29.7% (n = 19) for LCA, 10.9% (n = 7) for RCA, and 18.8% (n = 12) for combined LCA and RCA. ConclusionsCoronary height significantly decreased following CVG implantation. The majority of patients after bio-CVG were at a potential risk for coronary obstruction in future valve-in-valve procedures. Further studies are needed to identify the best possible technique for coronary reimplantation and other measures to diminish the risk for future coronary obstruction in this population.

Anatomic considerations after commando double valve reconstruction: insights for future valve-in-valve therapies.

The Commando technique for reconstruction of the aortomitral intervalvular fibrous body is effective to facilitate double valve surgery in cases of endocarditis or infiltrative calcification. The length of patch utilized in reconstruction of the intervalvular fibrous body has an important relationship to the geometry of the mitral valve (MV) and aortic valve (AV) and may impact on potential future valve-in-valve (VIV) therapy. Here we report anatomic measurements after Commando reconstruction in a small group of patients and analyse the impact of reconstruction techniques on transcatheter VIV therapies. Seven patients from January 2018 to April 2022 who underwent double valve surgery with the Commando technique with postoperative computed tomography (CT) scans were identified. Computed tomographic reconstruction of the AV and MV was performed using 3mensio software and virtual transcatheter valve replacement was performed. Two of these patients who had preoperative imaging was analysed to assess the change in aortomitral geometry resulting from reconstruction. Measurements for each patient post-reconstruction are given in the table. Aortomitral length was grossly inversely proportional to aortomitral angle (AMA). AMA and aortomitral curtain (AMC) length were significantly altered post-Commando in 2 analysed patients with pre- and postoperative computed tomography scan. Transcatheter AV and MV replacements were feasible in all patients post-Commando. The AMA was larger and more favorable for mitral VIV in patients in which the AMC was short. AMC length, as determined by location of AV annular sutures, may be an important consideration in surgical decision-making for VIV after the Commando procedure.

Street Lighting and Charging Stations with PATs Location Applying Artificial Intelligence

This research proposes a methodology with multi-objective optimization for the placement of Pumps operating As Turbines (PATs), energizing street lighting, devices for monitoring the water network, and charging stations for small electric vehicles such as bikes and scooters. This methodology helps to find the most profitable project for benefiting life quality and energy recovery through pumps operating as turbines, replacing virtual pressure reduction valves to locate the best point for decreasing pressure. PATs are selected by maximizing power recovery and minimizing pressure in the system as well as maximizing recoverable energy. Benefits analyzed include the reduction of carbon dioxide emissions and fuel use, as well as the saving of electricity consumption and benefiting socio-economic impact with street lighting, monitoring, and charging station. It was considered that each PAT proposed by the methodology will supply a street light pole, a station for monitoring the water network, and a charging station; under these established conditions, the return on investment is up to 1.07 at 12 years, with a power generation of 60 kWh per day.

Retraction: Virtual reality-guided aortic valve leaflet reconstruction for type 0 bicuspid aortic stenosis.

Retraction: Virtual reality-guided aortic valve leaflet reconstruction for type 0 bicuspid aortic stenosis.

Computational mimicking of surgical leaflet suturing for virtual aortic valve neocuspidization

Abstract The aortic valve neocuspidization (AVNeo) procedure requires the design of patient-specific neo-cusps which can be made numerically through the neovalve closure modelling. Prior the simulation, it is required to ‘suture virtually’ the neocusps into the patient’s aortic geometry, i.e., to find such state in which the neocusps are placed in the aortic root lumen without intersections of physical surfaces and neo-valve prolapse, and the position of the suture boundary satisfies the boundary conditions. To solve this problem, we tried to mimic neocusps suturing in Ozaki’s operation. As a result, we propose a new algorithm for ‘virtual suturing’ of given neocusps, considered as thin shells. The approach is able to work with both small and large (compared to an optimal size) neocusps and to handle each cusp independently of the others.

Analysis and Compensation Control of Engine Valve Response Delay Based on the Electro-Hydraulic Variable Valve Actuator

The time delay of variable valve actuators has a significant influence on engine valve lift tracking performance. For camless hydraulic valve actuators, engine valve response is affected by many factors, such as friction and control valve response. In this paper, engine valve response delay is investigated in depth. Experiment results show that engine valve motion delay can be divided into valve open delay and valve close delay. They are different even in the same engine cycle. Complicated delay characteristics make it difficult to build an accurate delay model. In this paper, a data-based delay observer is developed. To compensate the nonlinear valve delay, the virtual desired valve lift is designed. By synthesizing the virtual valve lift into the backstepping procedure, an engine valve lift tracking controller with delay compensation is developed. Compared with the P controller, the backstepping controller with delay compensation improved the engine valve lift tracking performance significantly. The experiment results show that the valve open error can be reduced by 18.33% and the valve close error can be reduced by 4% at least both at stable conditions and transient conditions. At stable conditions, the valve open error is not more than 0.39 °CA, and the valve close error is not more than 0.44 °CA.

Multi-Slice Computed Tomography Analysis in Patients Undergoing Transcatheter Aortic Valve Replacement - Impact of Workflows on Measurement of Virtual Aortic Annulus and Valve Size.

Exact and reliable measurements of anatomical dimensions in pre-procedural multi-slice computed tomography (MSCT) scans are crucial for optimal valve sizing and clinical results of transcatheter aortic valve replacement (TAVR). This study aimed to investigate interrater reliability between routinely used workflows for pre-procedural analysis. MSCT scans of 329 patients scheduled for TAVR were analyzed using both a 3mensio and SECTRA IDS7 platform. The results were retrospectively compared using the intraclass correlation coefficient, revealing excellent correlation in the analysis of simple diameters and poor correlation in the assessment of more complex structures with impact on calculated valve size.

Validation of Fatigue Model of a Hydraulic Shock Absorber Equipped with Shim Stack Valves

Abstract The aim of the paper is to formulate and validate the fatigue model of a shock absorber equipped with shim-based clamped valves. The fatigue model has application potential in a virtual valve system pre-selection process during the shock absorber design and configuration stage. It allows the required testing capacity at shock absorber manufacturers to be significantly reduced, i.e. the number of long-term and expensive fatigue tests performed on servo-hydraulic load frame testers. The shock absorber fatigue model is a combination of the previously developed finite element model [1] and analytical routines using the experimentally derived Wöhler characteristics of shim materials [2]. The fatigue model validation process was conducted with a high-performance servo-hydraulic load frame tester. Six shock absorbers were subjected to the same long-cycle kinematic sine-load and tested until initial valve damage symptoms appeared. The paper reports the fatigue calculation process and validation results. The obtained model accuracy in the range of ±30% error of shock absorber life-time prediction. This result is accurate enough for the model to be recommended as a quick-and-dirty engineering tool saving shock absorber development costs.

Commissural Versus Coronary Optimized Alignment During Transcatheter Aortic Valve Replacement.

The aims of this study were to determine the rate of noncentered coronary ostia and their risk for coronary overlap (CO) and to develop an improved orientation strategy for transcatheter aortic valve replacement (TAVR) devices taking into account anatomical cues to identify patients at risk for CO regardless of commissural alignment and compute an alternative, CO-free TAVR rotation angle for those patients. Commissural alignment during TAVR reduces CO risk. However, eccentricity of coronary ostia from the center of the sinus of Valsalva may result in CO even after perfect alignment of TAVR commissures. Baseline computed tomography from TAVR candidates helped identify distance from commissures to the right coronary artery (RCA) and the left coronary artery (LCA). Then, for each case, a virtual valve was simulated with ideal commissural or coronary alignment, and the degree of CO was determined. On the basis of the potential BASILICA (bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction) efficacy, 3 groups were defined: no risk for CO (>35° from neocommissure to coronary ostia), moderate risk (20°-35°), and severe risk (≤20°). Computed tomographic studies from 107 patients were included. After excluding 7 patients (poor quality or bicuspid valve), 100 patients were analyzed. The RCA showed greater eccentricity compared with the LCA (18.5° [IQR: 3.3°-12.8°] vs 6.5° [IQR: 3.3°-12.8°]; P< 0.001). The mean intercoronary angle was 140.0° ± 18.7° (95% CI: 136.3°-143.7°). Thirty-two patients had moderate to severe risk for CO (≤35°) despite ideal commissural alignment. Greater coronary eccentricity (cutoff for RCA, 24.5°; cutoff for LCA, 19°) and intercoronary angle >147.5° or<103° were associated with greater risk for moderate to severe CO despite commissural alignment (area under the curve: 0.97; 95% CI: 0.91-0.99). If optimal coronary alignment was simulated, this prevented severe CO in all cases and reduced moderate CO from 27% to 5% (P< 0.001). One third of patients would have CO during TAVR-in-TAVR despite commissural alignment; a 6-fold decrease in this risk was achieved with optimized coronary alignment. Coronary eccentricity and intercoronary angle were the main predictors.

Predictors of Left Ventricular Outflow Tract Obstruction After Transcatheter Mitral Valve Replacement in Severe Mitral Annular Calcification: An Analysis of the Transcatheter Mitral Valve Replacement in Mitral Annular Calcification Global Registry.

[Figure: see text].