Virtual Valve Research Articles

Towards patient-specific prediction of conduction abnormalities induced by transcatheter aortic valve implantation: a combined mechanistic modelling and machine learning approach.

Post-procedure conduction abnormalities (CA) remain a common complication of transcatheter aortic valve implantation (TAVI), highlighting the need for personalized prediction models. We used machine learning (ML), integrating statistical and mechanistic modelling to provide a patient-specific estimation of the probability of developing CA after TAVI. The cohort consisted of 151 patients with normal conduction and no pacemaker at baseline who underwent TAVI in nine European centres. Devices included CoreValve, Evolut R, Evolut PRO, and Lotus. Preoperative multi-slice computed tomography was performed. Virtual valve implantation with patient-specific computer modelling and simulation (CM&S) allowed calculation of valve-induced contact pressure on the anatomy. The primary composite outcome was new onset left or right bundle branch block or permanent pacemaker implantation (PPI) before discharge. A supervised ML approach was applied with eight models predicting CA based on anatomical, procedural and mechanistic data. CA occurred in 59% of patients (n = 89), more often after mechanical than first or second generation self-expanding valves (68% vs. 60% vs. 41%). CM&S revealed significantly higher contact pressure and contact pressure index in patients with CA. The best model achieved 83% accuracy (area under the curve 0.84) and sensitivity, specificity, positive predictive value, negative predictive value, and F1-score of 100%, 62%, 76%, 100%, and 82%. ML, integrating statistical and mechanistic modelling, achieved an accurate prediction of CA after TAVI. This study demonstrates the potential of a synergetic approach for personalizing procedure planning, allowing selection of the optimal device and implantation strategy, avoiding new CA and/or PPI.

Anatomic classification of mitral annular calcification for surgical and transcatheter mitral valve replacement.

From September 2015 to July 2019, 82 patients with MAC underwent MDCT at two institutions to evaluate for surgical mitral valve replacement (SMVR), transcatheter mitral valve replacement (TMVR), or medical management. Type 1 MAC was defined as <270° annular calcium and Type 2 as ≥270°. Absence/presence of predicted left ventricular outflow tract (LVOT) obstruction with virtual valve placement was used to further define Type 2 MAC into 2A/B for our treatment algorithm. Type 1 MAC was present in 51.2%, Type 2A in 18.3%, and Type 2B in 30.5%. Operable Type 1 patients (50.0%) underwent hybrid transatrial TMVR or SMVR. Type 2A underwent a variety of treatments, and Type 2B surgical candidates (40.0%) underwent hybrid transatrial TMVR secondary to difficult suture anchoring with significant MAC and predicted LVOT obstruction.At a follow-up of 29.6 ± 12.0 months, mortality was 42.7% with 46.3% in the intervention group and 39.0% in the medical group (p = 0.47). All percutaneous TMVR patients expired. This translated to a disproportionate number of Type 2A deaths (80.0% with intervention), but all were high/extreme surgical risk. The hybrid TMVR group consisted of 95.0% Type 1/2B patients and had a lower Society of Thoracic Surgeons predicted risk of operative mortality (7.4% vs. 9.2%, p = 0.43)/mortality. The highest mortality was seen in percutaneous TMVR Type 2A MAC patients, but they were at the greatest risk. Here we provide an objective MAC treatment algorithm for all-comers based on operability/anatomy.

Successful transcatheter aortic valve in valve implantation for degenerated trifecta bioprosthesis in a patient with a coronary anomaly

We report a case of transcatheter aortic valve implantation in a 79-year-old woman with a coronary anomaly who underwent surgical aortic valve replacement with a 23-mm Abbott Trifecta bioprosthesis. The procedure was performed in response to severe aortic stenosis caused by a bicuspid aortic valve. Computed tomography showed an anomalous origin of the right coronary artery from the left coronary sinus, with an interarterial course. Although the virtual transcatheter valve to coronary ostium distance-right coronary artery was short, the right coronary artery ostium was just behind the stent post. The externally mounted leaflet was unable to reach the coronary orifice beyond the stent post. This case highlights a successful transcatheter aortic valve implantation for stented bioprostheses with externally mounted leaflets when the virtual transcatheter valve to coronary ostium distance is shortened by a coronary anomaly.

Рossibilities of clinical application of modern nebulizers

The simplicity of converting medicinal solutions and suspensions into aerosols using mechanical and thermal energy, convenient delivery to the airways allows nebulizers to take a worthy place in the treatment of hospitalized and outpatient patients. Different types of nebulizers are available for use in the home and in medical settings (jet, ultrasound, membrane), and researches show that the performance and characteristics of the aerosol vary between different devices and manufacturers. Jet nebulizers are still the most used devices that do not require coordination of inhale and delivery of aerosol to the respiratory tract. To reduce the consumption of medicinal aerosol and optimize the air flow, virtual valve technology (V.V.T.) is being improved, and breath-actuated nebulizers are being created. The advantage of nebulizer therapy is the ability to apply large doses of medications, use substances that exist only in inhaled form. The choice falls on the nebulizer in cases where the patient can not use other delivery devices, for example, if the patient is unable to coordinate the inhalation and intake of the drug into the respiratory tract, with a severe exacerbation of obstructive disease, in the presence of motor disorders. The optimal delivery device for children of any age, including newborns, is a nebulizer. The most common indication for nebulizer therapy is the delivery of bronchodilators and inhaled corticosteroids for asthma or chronic obstructive pulmonary disease, as well as the treatment of upper respiratory tract diseases, in particular croup in children. An important place is given to nebulizers when it is necessary to prescribe certain mucolytics and antibiotics. In the treatment of emergency conditions, inhalation administration of drugs may be required, including situations when the patient is on mechanical ventilation or has a tracheostomy installed. The significance of nebulizers in the treatment of cystic fibrosis, pulmonary arterial hypertension, and alpha-1-antitrypsin deficiency is being studied. The possibilities of endobronchial delivery of heparin, insulin, and monoclonal antibodies are evaluated.

Feasibility of Transcatheter Aortic Valve Replacement in Prior Aortic Root Surgery

Aortic root replacement (ARR) introduces several anatomic complexities relevant to valve-in-valve (VIV)-transcatheter aortic valve replacement (TAVR) that may (1) increase the risk of coronary obstruction, (2) necessitate transcatheter valve overexpansion to accommodate large annuli, and (3) require alternative vascular access to navigate aortic kinking. Therefore, we aimed to quantify the feasibility of VIV-TAVR in patients who underwent aortic root surgery. Postoperative computed tomography scans were reviewed for consecutive patients who underwent ARR between 2005 and 2019 to obtain measurements relevant for VIV-TAVR planning. Virtual transcatheter valve to coronary ostia distance was measured to assess the risk of coronary obstruction. Root morphologies were classified into 1 of 4 groups based on aortic graft type, aortic diameter at the sinotubular junction, sinus height, estimated transcatheter heart valve height, and diameter. VIV-TAVR was projected to be complex in patients with an aortic kink, extremely large annulus, or heightened risk of coronary obstruction. Among 848 patients who underwent ARR during the 15-year study period, qualifying contrast-enhanced scans post-ARR were performed in 81 patients. Complex VIV-TAVR was anticipated in 50.6% of subjects. Patients with abnormal root anatomy experienced increased odds of complex VIV-TAVR relative to patients with normal root physiology (ie, sinotubular junction diameter>transcatheter heart valve diameter, sinus height>transcatheter heart valve height) or those who received straight tube grafts (odds ratio, 4.53 [95% CI, 1.02-20.1], P=0.046). The odds of complex VIV-TAVR were also higher among patients who underwent aortic valve replacement-ARR with a stentless bioprosthesis (stentless versus stented, odds ratio, 4.63 [95% CI, 1.40-15.3], P=0.012; stentless versus valve-sparing ARR, odds ratio, 3.78 [95% CI, 1.14-12.5], P=0.029). ARR patients with atypical root morphologies or those who underwent valve replacement with stentless bioprostheses may be at high risk for complex VIV-TAVR. Prospective evaluation is required to assess the impact of these conclusions on procedural feasibility.

Geometrical predictors of small virtual neoLVOT size in functional mitral regurgitation

Abstract Background LVOT obstruction is a potentially lethal complication of transcatheter mitral valve replacement (TMVR). An anticipated neoLVOT area of &amp;lt;2cm2 is presumed to imply prohibitive risk. Measurement of the anticipated neoLVOT can be time consuming and requires specialist software to facilitate virtual valve implantation. Purpose To determine simple geometrical predictors of prohibitive neoLVOT size. Methods 165 consecutive, non-calcific FMR patients referred to a transcatheter heart valve program were analysed. Segmentation of the mitral annulus and left heart geometry was performed using CT. Suitability for a default D-shaped TMVR was determined by proprietary annular inclusion criteria. Systolic neoLVOT area was determined via virtual valve implantation of the default TMVR. Results Sufficient image data for annular and neoLVOT suitability assessment was available in 152 patients. 105 patients (69%) were suitable for TMVR based on annular measurements. Of these, neoLVOT area was &amp;gt;2cm2 in 88 (84%). Overall, compared to patients not suitable for TMVR (n=64), those suitable had larger ventricles with lower LVEF, and larger annuli (table 1). Using binomial logistic regression involving the variables within table 1, LVESD was the sole statistically significant variable to predict neoLVOT area of &amp;lt;2cm2 (p=0.02). LVESD &amp;lt;48mm had 82% sensitivity and 94% specificity for the presence of prohibitive neoLVOT (figure 1). Conclusion Smaller LVESD is a strong predictor of small neoLVOT, and hence LVOT obstruction post default D-shaped TMVR implantation. This simple measure may therefore be used to streamline patient selection for advanced pre-procedural imaging analysis. Predicting NeoLVOT size &amp;lt;2 cm2 Funding Acknowledgement Type of funding source: None

Preoperative multidetector computed tomography for isolated surgical aortic valve replacement: Planning for future transcatheter options.

Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) has become a valuable option in patients with bioprosthetic failure. However, potential issues with ViV TAVR may occur in patients with high-risk anatomy for coronary obstruction and patients with baseline smaller bioprosthetic valves at risk for patient prosthesis mismatch. The purpose of this study was, therefore, to use preoperative electrocardiography-gated, multidetector computed tomography (MDCT) in patients undergoing isolated surgical aortic valve replacement (SAVR) to (1) identify which would be high risk for coronary occlusion with ViV TAVR, and (2) predict intraoperative SAVR sizing. Among 223 patients from our institutions' database that underwent SAVR for aortic insufficiency (AI) or aortic stenosis (AS) between January 2012 and January 2020, 48 patients had MDCT imaging before surgery (AI; n = 31, AS; n = 17). Of all patients, 67% (n = 32) were bicuspid morphology. With the use of virtual valve implantation, all patients with AI and bicuspid AS had feasible anatomy for ViV TAVR, while 38% of patients with tricuspid AS were high risk for coronary obstruction. There was a strong correlation between actual valve size implanted and preoperative MDCT measurements using annulus average diameter, area, and/or perimeter. Preoperative MDCT in patients undergoing SAVR is a useful tool for lifetime management, particularly in patients with tricuspid AS. Decisions for surgical management may change based on MDCT's ability to predict intraoperative SAVR size and determine which patients may be high-risk candidates for future ViV TAVR due to coronary artery obstruction.

Predicting paravalvular leak after transcatheter mitral valve replacement using commercially available software modeling

BackgroundThere is limited data identifying patients at risk for significant mitral regurgitation (MR) after transcatheter mitral valve replacement (TMVR). We hypothesized that software modeling based on computed tomography angiography (CTA) can predict the risk of moderate or severe MR after TMVR. Methods58 consecutive patients underwent TMVR at two institutions, including 31 valve-in-valve, 16 valve-in-ring, and 11 valve-in-mitral annular calcification. 12 (20%) patients developed moderate or severe MR due to paravalvular leak (PVL). ResultsThe software model correctly predicted 8 (67%) patients with significant PVL, resulting in sensitivity of 67%, specificity 96%, positive predictive value 89%, and negative predictive value 86%. There was excellent agreement between CTA readers using software modeling to predict PVL (kappa 0.92; p < 0.01). On univariate analysis, CTA predictors of moderate or severe PVL included presence of a gap between the virtual valve and mitral annulus on the software model (OR 48; p < 0.01), mitral annular area (OR 1.02; p 0.01), and % valve oversizing (OR 0.9; p 0.01). On multivariate analysis, only presence of a gap on the software model remained significant (OR 36.8; p < 0.01). ConclusionsSoftware modeling using pre-procedural CTA is a straightforward method for predicting the risk of moderate and severe MR due to PVL after TMVR.

Coronary Protection to Prevent Coronary Obstruction During TAVR: A Multicenter International Registry

ObjectivesThe aim of this study was to investigate the safety and efficacy of coronary protection by preventive coronary wiring and stenting across the coronary ostia in patients at high risk for coronary obstruction after transcatheter aortic valve replacement (TAVR). BackgroundCoronary obstruction following TAVR is a life-threatening complication with high procedural and short-term mortality. MethodsData were collected retrospectively from a multicenter international registry between April 2011 and February 2019. ResultsAmong 236 patients undergoing coronary protection with preventive coronary wiring, 143 had eventually stents implanted across the coronary ostia after valve deployment. At 3-year follow-up, rates of cardiac death were 7.8% in patients receiving stents and 15.7% in those not receiving stents (adjusted hazard ratio: 0.42; 95% confidence interval: 0.14 to 1.28; p = 0.13). There were 2 definite stent thromboses (0.9%) in patients receiving stents, both occurring after TAVR in “valve-in-valve” procedures. In patients not receiving stents, there were 4 delayed coronary occlusions (DCOs) (4.3%), occurring from 5 min to 6 h after wire removal. Three cases occurred in valve-in-valve procedures and 1 in a native aortic valve procedure. Distance between the virtual transcatheter valve and the protected coronary ostia <4 mm was present in 75.0% of patients with DCO compared with 30.4% of patients without DCO (p = 0.19). ConclusionsIn patients undergoing TAVR at high risk for coronary obstruction, preventive stent implantation across the coronary ostia is associated with good mid-term survival rates and low rates of stent thrombosis. Patients undergoing coronary protection with wire only have a considerable risk for DCO.

Frequency domain modelling of pipe transient flow with the virtual valves method to reduce linearization errors

For Modeling the transient flow in a pipeline by Frequency Response Method (FRM), the nonlinear terms of the governing equations and boundary conditions should be linearized. Significant nonlinearities are associated with the steady friction and valve equations. This study reviews the FRM and its range of validity in accordance with the linearization errors and, proposes some remedies to reduce the errors. To improve the FRM accuracy, the linearization of valve equation is modified and a new frequency-dependent correction factor is introduced. Also, to capture the system responses at the higher-order frequencies due to the nonlinear terms, the method of virtual valves is introduced. Through this method, the system’s real nonlinear valve oscillating at a main frequency ω is represented by a number of linear virtual valves oscillating at the main and some higher-order frequencies 2ω,3ω,⋯ that may appear in the system’s response spectra due to the nonlinearity of valve equation. The modified FRM (M-FRM) is compared with the standard FRM (S-FRM) as well as the Method of Characteristics (MOC) on the energy phase diagram. The results demonstrate that the modifications dramatically improve the validity of the FRM even for large sizes of valve perturbation. The generality of the method is also validated by solving several pipe-reservoir-valve systems with different specifications.

Predictors of Left Ventricular Outflow Tract Obstruction After Transcatheter Mitral Valve Replacement

ObjectivesThe aim of this study was to evaluate the predictors of left ventricular outflow tract (LVOT) obstruction after transcatheter mitral valve replacement (TMVR). BackgroundLVOT obstruction is a major concern with TMVR, but limited data exist regarding its predictors and impact on outcomes. MethodsPatients with pre-procedural multidetector row computed tomography (MDCT) undergoing TMVR for failed mitral bioprosthetic valves (valve-in-valve), annuloplasty rings (valve-in-ring), and mitral annular calcification (valve-in-MAC) were included in this study. Echocardiographic and procedural characteristics were recorded, and comprehensive assessment with MDCT was performed to identify the predictors of LVOT obstruction (defined as an increment of mean LVOT gradient ≥10 mm Hg from baseline). The new LVOT (neo-LVOT) area left after TMVR was estimated by embedding a virtual valve into the mitral annulus on MDCT, simulating the procedure. ResultsAmong 194 patients with pre-procedural MDCT undergoing TMVR (valve-in-valve, 107 patients; valve-in-ring, 50 patients; valve-in-MAC, 37 patients), LVOT obstruction was observed in 26 patients (13.4%), with a higher rate after valve-in-MAC than valve-in-ring and valve-in-valve (54.1% vs. 8.0% vs. 1.9%; p < 0.001). Patients with LVOT obstruction had significantly higher procedural mortality compared with those without LVOT obstruction (34.6% vs. 2.4%; p < 0.001). Receiver-operating characteristic curve analysis showed that an estimated neo-LVOT area ≤1.7 cm2 predicted LVOT obstruction with sensitivity of 96.2% and specificity of 92.3%. ConclusionsLVOT obstruction after TMVR was associated with higher procedural mortality. A small estimated neo-LVOT area was significantly associated with LVOT obstruction after TMVR and may help identify patients at high risk for LVOT obstruction.

Toward predictive modeling of catheter-based pulmonary valve replacement into native right ventricular outflow tracts.

Pulmonary insufficiency is a consequence of transannular patch repair in Tetralogy of Fallot (ToF) leading to late morbidity and mortality. Transcatheter native outflow tract pulmonary valve replacement has become a reality. However, predicting a secure, atraumatic implantation of a catheter-based device remains a significant challenge due to the complex and dynamic nature of the right ventricular outflow tract (RVOT). We sought to quantify the differences in compression and volume for actual implants, and those predicted by pre-implant modeling. We used custom software to interactively place virtual transcatheter pulmonary valves (TPVs) into RVOT models created from pre-implant and post Harmony valve implant CT scans of 5 ovine surgical models of TOF to quantify and visualize device volume and compression. Virtual device placement visually mimicked actual device placement and allowed for quantification of device volume and radius. On average, simulated proximal and distal device volumes and compression did not vary statistically throughout the cardiac cycle (P = 0.11) but assessment was limited by small sample size. In comparison to actual implants, there was no significant pairwise difference in the proximal third of the device (P > 0.80), but the simulated distal device volume was significantly underestimated relative to actual device implant volume (P = 0.06). This study demonstrates that pre-implant modeling which assumes a rigid vessel wall may not accurately predict the degree of distal RVOT expansion following actual device placement. We suggest the potential for virtual modeling of TPVR to be a useful adjunct to procedural planning, but further development is needed.

Study of the vortex based virtual valve micropump

The research and development of piezoelectric valve-less micropumps have become an increasingly popular topic for decades. A highly efficient valve-less micropump is necessary to deliver liquids for microfluidic control systems. Study of the flow mechanism in the valve-less micropump may help to further improve the pumping efficiency. In this paper, a dynamic finite element model is used to investigate the mechanism of a valve-less micropump with a diffuser/nozzle. The simulation result shows that the flow performance of a valve-less micropump is not only dependent on the diffuser/nozzle but is also related to the entire structure. When fluid flows through the nozzle, the chamber connected to the nozzle end is considered as a diffuser with an angle of 180°. This diffuser is located in the jet flow region, where the high velocity fluid generates a vortex in the interfacial area of the nozzle and chamber. Such a vortex works as a ‘virtual valve’, which can block the reflux and result in unidirectional flow. Besides, the vortex degree is tightly related to fluid velocity, which is determined by the input voltage. When the input voltage is larger than the threshold voltage (20 V), the virtual valve is activated, and the flow rate of the micropump increases rapidly with the input voltage. The simulation analysis conclusions are verified by experiment results. The experimental results demonstrate that the maximum flow rate of 5.4 ml min−1 is finally obtained, which is comparable to a typical valve micropump.

Left ventricular outflow obstruction predicts increase in systolic pressure gradients and blood residence time after transcatheter mitral valve replacement

Left ventricular outflow tract (LVOT) obstruction is a relatively common consequence of transcatheter mitral valve replacement (TMVR). Although LVOT obstruction is associated with heart failure and adverse remodelling, its effects upon left ventricular hemodynamics remain poorly characterised. This study uses validated computational models to identify the LVOT obstruction degree that causes significant changes in ventricular hemodynamics after TMVR. Seven TMVR patients underwent personalised flow simulations based on pre-procedural imaging data. Different virtual valve configurations were simulated in each case, for a total of 32 simulations, and the resulting obstruction degree was correlated with pressure gradients and flow residence times. These simulations identified a threshold LVOT obstruction degree of 35%, beyond which significant deterioration of systolic function was observed. The mean increase from baseline (pre-TMVR) in the peak systolic pressure gradient rose from 5.7% to 30.1% above this threshold value. The average blood volume staying inside the ventricle for more than two cycles also increased from 4.4% to 57.5% for obstruction degrees above 35%, while the flow entering and leaving the ventricle within one cycle decreased by 13.9%. These results demonstrate the unique ability of modelling to predict the hemodynamic consequences of TMVR and to assist in the clinical decision-making process.

Development of a modeling pipeline for the prediction of hemodynamic outcome after virtual mitral valve repair using image-based CFD.

Severe mitral valve regurgitation can either be treated by a replacement or a repair of the valve. The latter is recommended due to lower perioperative mortality and better long-term survival. On the other hand, recurrence rates after mitral valve repair are high compared to those after replacements and the repair intervention can cause induced mitral valve stenosis. So far, there are no methods to predict the hemodynamic outcome of a chosen treatment or to compare different treatment options in advance. To overcome this, diastolic mitral valve hemodynamics are simulated using computational fluid dynamics after different virtual treatments of the valve. The left ventricular geometry of one patient was reconstructed using trans-esophageal echocardiography and computed tomography data. Pre-op hemodynamics are simulated using a referenced wall model to avoid expansive modeling of wall motion. Subsequently, the flow structures are compared to in vivo measurements. After manipulating the patient-specific geometry in order to mimic a restrictive mitral annuloplasty as well as a MitraClip intervention, hemodynamics results are calculated. Good agreements exist between calculated pre-op hemodynamics and in vivo measurements. The virtual annuloplasty did not result in any remarkable change of hemodynamics. Neither the pressure drop nor the velocity field showed strong differences. In contrast, the virtual MitraClip intervention led to a complete change in blood flow structures as well as an elevated pressure drop across the valve. The presented approach allows fast simulation of the diastolic hemodynamic situation before and after treatment of a mitral valve insufficiency. However, this approach is limited to the early diastolic phase of the cardiac cycle and needs to be validated using a larger sample size.

On-chip density mixer enhanced by air chamber.

This paper proposes an on-chip density mixer that can achieve even density in a target chamber with a swirling flow enhanced by an air chamber. The system is composed of a main channel, a target chamber where two liquids with different densities are included, an isolated air chamber, and an external vibration pump driven by a piezo actuator at the entrance of the main channel. The air chamber is expected to amplify the vibration owing to structure softening. The amplification would be more pronounced at the resonance frequencies of the structure. We developed the system and conducted experiments. We showed that the swirling motion in the target chamber with an air chamber is stronger than that without an air chamber. We also confirmed that the time resulting in even density is shorter when the pump is driven at a resonance frequency. An air-based virtual valve is introduced for maintaining a constant density in the target chamber.

Modeling and simulation framework of aortic valve for hemodynamic evaluation of aortic root replacement surgery outcomes

Abstract The valve-sparing aortic root surgery is a common treatment of several aortic diseases. Although, the aortic valves are generally fixed in an even distribution during these operations, recently developed special tools enable the back-sewing of the valves in the original, patient specific distribution that likely provides better hemodynamic functions after the operation. The aim of the presented work is to quantitatively analyze the hemodynamic outcomes of the alternative valve-sparing root surgery operations by using computer simulation. In the paper the developed modeling, elastic, and fluid simulation framework of the aortic root is introduced. The workflow implemented by the framework covers the patient specific aortic root geometry modeling using CT or MR data, finite element simulation based virtual aortic valve sewing, and blood flow parameter calculation in the aortic root. Our custom-developed simulation techniques use simplifications applicable directly for aortic valve simulation resulting in reasonable computational complexity. The preliminary results of aortic valve modeling of 10 patients are presented at the end of the paper.

Impact of patient-specific LVOT inflow profiles on aortic valve prosthesis and ascending aorta hemodynamics

Patient-specific models become increasingly important in cardiovascular research as they allow prediction of surgical procedures. While the left ventricular outflow profile is an essential boundary condition, it remains unknown before treatment takes place. To overcome this problem, hemodynamics after virtual valve replacement were calculated based on different inlet profiles at the left ventricular outflow tract: a generic plug profile and a profile derived from 4D-flow-MRI. Spatially averaged parameters within the aorta were not significantly altered using either profile. A generic profile might be sufficient for the prediction of hemodynamics, circumventing the problem of predicting change in patient-specific boundary conditions.

Neochordoplasty versus leaflet resection for ruptured mitral chordae treatment: Virtual mitral valve repair

Degenerative mitral valve (MV) disease involving mitral prolapse is one of the most prevalent MV pathologies. Quadrangular leaflet resection and neochordoplasty demonstrate excellent clinical outcomes for the treatment of posterior leaflet prolapse. We evaluated the functional and biomechanical characteristics of a virtual pathologic MV model suffering from chordal rupture, performed virtual neochordoplasty and quadrangular leaflet resection, and compared the two post-repair MV functions. The pre-repair MV demonstrated severe posterior leaflet prolapse due to the ruptured P2 chordae and excessive stress concentration. Both repair techniques revealed reduced leaflet prolapse, decreased stress concentration, and restored leaflet coaptation. While neochordoplasty demonstrated further improved leaflet coaptation and superior posterior leaflet mobility, leaflet resection showed more uniform leaflet stress distributions. Virtual MV repair simulation has the ability to predict and quantitate biomechanical and functional improvement following MV repair. This strategy has the potential to help determine the most effective repair technique to restore MV function.

Incidence, predictors, and clinical outcomes of coronary obstruction following transcatheter aortic valve replacement for degenerative bioprosthetic surgical valves: insights from the VIVID registry.

There are limited data on coronary obstruction following transcatheter valve-in-valve (ViV) implantation inside failed aortic bioprostheses. The objectives of this study were to determine the incidence, predictors, and clinical outcomes of coronary obstruction in transcatheter ViV procedures. A total of 1612 aortic procedures from the Valve-in-Valve International Data (VIVID) Registry were evaluated. Data were subject to centralized blinded corelab computed tomography (CT) analysis in a subset of patients. The virtual transcatheter valve to coronary ostium distance (VTC) was determined. A total of 37 patients (2.3%) had clinically evident coronary obstruction. Baseline clinical characteristics in the coronary obstruction patients were similar to controls. Coronary obstruction was more common in stented bioprostheses with externally mounted leaflets or stentless bioprostheses than in stented with internally mounted leaflets bioprostheses (6.1% vs. 3.7% vs. 0.8%, respectively; P < 0.001). CT measurements were obtained in 20 (54%) and 90 (5.4%) of patients with and without coronary obstruction, respectively. VTC distance was shorter in coronary obstruction patients in relation to controls (3.24 ± 2.22 vs. 6.30 ± 2.34, respectively; P < 0.001). Using multivariable analysis, the use of a stentless or stented bioprosthesis with externally mounted leaflets [odds ratio (OR): 7.67; 95% confidence interval (CI): 3.14-18.7; P < 0.001] associated with coronary obstruction for the global population. In a second model with CT data, a shorter VTC distance predicted this complication (OR: 0.22 per 1 mm increase; 95% CI: 0.09-0.51; P < 0.001), with an optimal cut-off level of 4 mm (area under the curve: 0.943; P < 0.001). Coronary obstruction was associated with a high 30-day mortality (52.9% vs. 3.9% in the controls, respectively; P < 0.001). Coronary obstruction following aortic ViV procedures is a life-threatening complication that occurred more frequently in patients with prior stentless or stented bioprostheses with externally mounted leaflets and in those with a short VTC.