Use of Cardiac Computerized Tomography to Predict Neo-Left Ventricular Outflow Tract Obstruction Before Transcatheter Mitral Valve Replacement

Etiologies and Impact of Exclusion Rates for Transcatheter Mitral and Tricuspid Valve Structural Heart Clinical Trials at a High-Volume Quaternary Care Hospital

There are various devices under clinical investigation for transcatheter mitral valve intervention and transcatheter tricuspid valve intervention (TTVI); however, the exclusion rates remain high. We aimed to investigate the exclusion rates for transcatheter mitral valve repair (TMVr), transcatheter mitral valve replacement (TMVR), transcatheter tricuspid valve repair (TTVr), and transcatheter tricuspid valve replacement (TTVR). There were 129 patients who were referred to St. Francis Hospital & Heart Center valve clinic and completed screening between January 2021 and July 2022. The causes for exclusion were classified into 4 categories: patient withdrawal, anatomic unsuitability, clinical criteria, and medical futility. In 129 patients, the exclusion rates for TMVr, TMVR, TTVr, and TTVR were 81%, 85%, 91%, and 87%, respectively. Patient withdrawal and medical futility were leading etiologies for exclusion, followed by anatomic unsuitability. TMVr had the highest rate of patient withdrawal (64%) and the lowest anatomic unsuitability (5%) because of short posterior leaflet length. Replacement interventions have a higher anatomic unsuitability (33%) than repair interventions (17%) (p = 0.04). Most exclusions of anatomic unsuitability were because of mitral stenosis or small annulus size for TMVR and large annulus size for TTVR. A total of 50% of exclusions from TTVr were because of the presence of pacemaker/defibrillator leads. In patients excluded from their respective trials, patients being referred for TMVr had the highest recurrent hospitalization and repair group had a higher mortality (p <0.01 and p = 0.01, respectively). In conclusion, the exclusion rates for transcatheter mitral valve intervention and TTVI trials remain high because of various reasons, limiting patient enrollment and treatment. This supports the need for further device improvement or exploring alternative means of therapy.

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

BACKGROUND

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.

AIM

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Transcatheter mitral valve implantation for native valve disease

Mitral regurgitation is the second most frequent heart valve disease in Europe and the most frequent in the US. Although surgery is the therapy of choice when intervention is indicated, transcatheter mitral valve repair or replacement are alternatives for patients who are not eligible for surgery. However, the development of transcatheter mitral valves is slower than expected. Although several transcatheter heart valves have been developed, only one has been commercialised. Indeed, most of these devices are being evaluated in clinical studies, with promising initial results. In this review, we propose an overview on transcatheter mitral valve replacement for the treatment of native mitral valve disease, from indication to results, including patients with severe annular calcification, and we provide you with a glimpse into the future of these therapies.

Early Biological Valve Failure: Structural Valve Degeneration, Thrombosis, or Endocarditis?

Biological valve failure (BVF) is an inevitable condition that compromises the durability of biological heart valves (BHVs). It stems from various causes, including rejection, thrombosis, and endocarditis, leading to a critical state of valve dysfunction. Echocardiography, cardiac computed tomography, cardiac magnetic resonance, and nuclear imaging play pivotal roles in the diagnostic multimodality workup of BVF. By providing a comprehensive overview of the pathophysiology of BVF and the diagnostic approaches in different clinical scenarios, this review aims to aid clinicians in their decision-making process. The significance of early detection and appropriate management of BVF cannot be overstated, as these directly impact patients' prognosis and their overall quality of life. Ensuring timely intervention and tailored treatments will not only improve outcomes but also alleviate the burden of this condition on patients' life. By prioritizing comprehensive assessments and adopting the latest advancements in diagnostic technology, medical professionals can significantly enhance their ability to manage BVF effectively.

Post-procedural structural heart CT imaging: TAVR, TMVR, and other interventions

Transcatheter valve replacement has experienced substantial growth in the past decade and this technique can now be used for any of the four heart valves. Transcatheter aortic valve replacement (TAVR) has overtaken surgical aortic valve replacement. Transcatheter mitral valve replacement (TMVR) is often performed in pre-existing valves or after prior valve repair, although numerous devices are undergoing trials for replacement of native valves. Transcatheter tricuspid valve replacement (TTVR) is similarly under active development. Lastly, transcatheter pulmonic valve replacement (TPVR) is most often used for revision treatment of congenital heart disease. Given the growth of these techniques, radiologists are increasingly called upon to interpret post-procedural imaging for these patients, particularly with CT. These cases will often arise unexpectedly and require detailed knowledge of potential post-procedural appearances. We review both normal and abnormal post-procedural findings on CT. Certain complications-device migration or embolization, paravalvular leak, or leaflet thrombosis-can occur after replacement of any valve. Other complications are specific to each type of valve, including coronary artery occlusion after TAVR, coronary artery compression after TPVR, or left ventricular outflow tract obstruction after TMVR. Finally, we review access-related complications, which are of particular concern due to the requirement of large-bore catheters for these procedures.

Transesophageal Echocardiographic Screening for Structural Heart Interventions

PURPOSE OF REVIEW

Percutaneous structural interventions have provided patients with an effective therapeutic option, and its growth has been aided by echocardiography. We describe the vital role that transesophageal echocardiography (TEE) plays in screening patients prior to their procedure.

RECENT FINDINGS

A multimodality imaging approach is employed by the valve team, but TEE plays a unique role in diagnosis and planning. Utilization of all TEE views and features such as biplane, 3D imaging, and multiplanar reconstruction ensures accurate assessment of the structural lesion of interest. The role of TEE remains essential in the planning of structural interventions, and these studies should be performed in a systematic and comprehensive manner.

Patient-specific fluid simulation of transcatheter mitral valve replacement in mitral annulus calcification

Introduction

Transcatheter mitral valve replacement is a promising alternative to open-heart surgery in elderly patients. Patients with severe mitral annulus calcification (MAC) are a particularly high-risk population, where postprocedural complications can have catastrophic effects. Amongst these, obstruction of the left ventricular outflow tract can lead to ventricular hypertrophic remodeling and subsequent heart failure, while subclinical valve thrombosis can result in early bioprosthetic valve failure.

Methods

To elucidate the mechanisms of left ventricular outflow tract obstruction and valve thrombosis following valve-in-MAC procedures, we used image processing and Computational Fluid Dynamics (CFD) software to generate patient- and device-specific models based on preprocedural CT data. Personalized computer simulations were performed to predict the left ventricular haemodynamics after implantation in three patients with severe MAC.

Results

The simulations have successfully captured the increased pressure gradient in the left ventricular outflow tract as a result of the partial obstruction due to the implanted valve. Regions of wall shear stress above the threshold value for platelet activation were also observed on the bioprosthetic frame as a result of the reduced outflow tract area, which led to increases in flow resistance and blood residence time inside the ventricle. Consistent with these findings, areas of slow recirculating flow and blood stasis formed near the valve frame, creating potential pro-thrombotic conditions.

Discussion

This study provides insight into the relationship between size and shape of the outflow tract post-implantation, pressure gradients and pro-thrombotic flow metrics such as wall shear stress and blood residence time. Results show the potential of CFD modeling to bring key functional metrics into preprocedural assessment for a comprehensive evaluation of post-procedural risks beyond anatomical factors. Following further validation and extension to the atrial chamber, this approach can provide an in-depth analysis of the likelihood of valvular thrombosis.

Utilization of Two- and Three-Dimensional Transesophageal Echocardiography in Successfully Guiding Transcatheter Mitral Valve in Bioprosthetic Mitral Valve/Mitral Ring Implantation without Complications in Patients with Thrombus in Left Atrium/Left Atrial Appendage

BACKGROUND

The aim of this study is to describe, for the first time to our knowledge, the utilization of both two-dimensional (2D) and three-dimensional (3D) transesophageal echocardiography (TEE) in successfully performing transcatheter mitral valve (MV) in bioprosthetic MV/MV annulopasty ring implantation using the apical approach in 12 patients (pts) with co-existing left atrial appendage (LAA) and/or LA (left atrium) body thrombus, which is considered a contraindication for this procedure.

METHODS AND RESULTS

All pts were severely symptomatic with severe bioprosthetic MV stenosis/regurgitation except one with a previous MV annuloplasty ring and severe native MV stenosis. Thrombus in LAA and/or LA body was noted in all by 2D and 3DTEE. All were at high/prohibitive risk for redo operation and all refused surgery. Utilizing both 2D and 3DTEE, especially 3DTEE, guidewires and the prosthesis deployment system could be manipulated under direct vision into the LA avoiding any contact with the thrombus. The procedure was successful in all with amelioration of symptoms and no embolic or other complications over a mean follow-up of 21 months.

CONCLUSION

Our study demonstrates the feasibility of successfully performing this procedure in pts with thrombus in LAA and/or LA body without any complications.

Automated mitral valve assessment for transcatheter mitral valve replacement planning

Transcatheter mitral valve replacement (TMVR) has emerged as a minimally invasive alternative for treating patients suffering from mitral valve disease. The number of TMVR procedures is expected to rise as devices currently in clinical trials obtain approval for commercialization. Automating the planning of such interventions becomes, therefore, more relevant in an attempt to decrease inter-subject discrepancies and time spent in patient assessment. This study evaluates the performance of an automated method for detection of anatomical landmarks and generation of relevant measurements for device selection and positioning. Cardiac CT scans of 70 patients were collected retrospectively. Fifty scans were used to generate a statistical shape model (SSM) of the left heart chambers at ten different timepoints, whereas the remaining 20 scans were used for validation of the automated method. The clinical measurements resulting from the anatomical landmarks generated automatically were compared against the measurements obtained through the manual indication of the corresponding landmarks by three observers, during systole and diastole. The automatically generated measurements were in close agreement with the user-driven analysis, with intraclass correlation coefficients (ICC) consistently lower for the saddle-shaped (ICCArea = 0.90, ICCPerimeter 2D = 0.95, ICCPerimeter 3D = 0.93, ICCAP-Diameter = 0.71, ICCML-Diameter = 0.90) compared to the D-shaped annulus (ICCArea = 0.94, ICCPerimeter 2D = 0.96, ICCPerimeter 3D = 0.96, ICCAP-Diameter = 0.95, ICCML-Diameter = 0.92). The larger differences observed for the saddle shape suggest that the main discrepancies occur in the aorto-mitral curtain. This is supported by the fact that statistically significant differences are observed between the two annulus configurations for area (p < 0.001), 3D perimeter (p = 0.009) and AP diameter (p < 0.001), whereas errors for 2D perimeter and ML diameter remained almost constant. The mitral valve center deviated in average 2.5 mm from the user-driven position, a value comparable to the inter-observer variability. The present study suggests that accurate mitral valve assessment can be achieved with a fully automated method, what could result in more consistent and shorter pre-interventional planning of TMVR procedures.

Usefulness of computed tomography to predict residual mitral regurgitation after transcatheter mitral valve edge-to-edge repair

BACKGROUND

Multidetector computed tomography (MDCT) can provide valuable information for preprocedural planning of transcatheter mitral valve interventions. However, no data exist on MDCT parameters predicting residual mitral regurgitation (MR) post-MitraClip (Abbott Laboratories, Abbott Park, IL, USA).

METHODS

We analyzed preprocedural MDCTs of 78 consecutive patients with secondary MR undergoing MitraClip implantation at our institution. Moderate-or-severe mitral leaflet calcification (MLC) was defined as calcification, with-or-without mitral annular calcification, extending beyond the mitral leaflet base. Residual MR was assessed by postprocedural transesophageal echocardiography, and clinical outcomes were assessed at 1-year.

RESULTS

Fifteen patients (19 %) had residual MR ≥2+. Compared to patients with none-or-mild residual MR, MDCT-derived mitral valve orifice area (MVOA) to mitral annulus area (MAA) ratio was significantly lower (0.32 ± 0.06 vs. 0.39 ± 0.09; p = 0.003), and the prevalence of MLC was higher (40 % vs. 18 %; p = 0.057) in those with residual MR ≥2+. Furthermore, the MVOA/MAA ratio and MLC were independent predictors of residual MR ≥2+ post-MitraClip [adjusted odds ratio (OR_adj): 0.88 (0.80-0.97) and 5.50 (1.16-26.23), respectively]. On receiver-operating-characteristic-curve analysis, MVOA/MAA ratio <0.31 had a sensitivity of 87 % and a specificity of 60 % for residual MR ≥2+. When patients were classified according to the presence of MLC and an MVOA/MAA ratio <0.31, those with both parameters had significantly higher rates of postprocedural residual MR ≥2+ and mitral reintervention at 1-year than those with only one, and those without both parameters.

CONCLUSIONS

In patients with secondary MR undergoing the MitraClip procedure, preprocedural MDCT parameters, specifically MVOA/MAA ratio and MLC, are useful to predict postprocedural residual MR.

Fluid structure computational model of simulating mitral valve motion in a contracting left ventricle

BACKGROUND

Fluid structure interaction simulations h hold promise in studying normal and abnormal cardiac function, including the effect of fluid dynamics on mitral valve (MV) leaflet motion. The goal of this study was to develop a 3D fluid structure interaction computational model to simulate bileaflet MV when interacting with blood motion in left ventricle (LV).

METHODS

The model consists of ideal geometric-shaped MV leaflets and the LV, with MV dimensions based on human anatomical measurements. An experimentally-based hyperelastic isotropic material was used to model the mechanical behaviour of the MV leaflets, with chordae tendineae and papillary muscle tips also incorporated. LV myocardial tissue was prescribed using a transverse isotropic hyperelastic formulation. Incompressible Navier-Stokes fluid formulations were used to govern the blood motion, and the Arbitrary Lagrangian Eulerian (ALE) method was employed to determine the mesh deformation of the fluid and solid domains due to trans-valvular pressure on MV boundaries and the resulting leaflet movement.

RESULTS

The LV-MV generic model was able to reproduce physiological MV leaflet opening and closing profiles resulting from the time-varying atrial and ventricular pressures, as well as simulating normal and prolapsed MV states. Additionally, the model was able to simulate blood flow patterns after insertion of a prosthetic MV with and without left ventricular outflow tract flow obstruction. In the MV-LV normal model, the regurgitant blood flow fraction was 10.1 %, with no abnormality in cardiac function according to the mitral regurgitation severity grades reported by the American Society of Echocardiography.

CONCLUSION

Our simulation approach provides insights into intraventricular fluid dynamics in a contracting LV with normal and prolapsed MV function, as well as aiding in the understanding of possible complications after transcatheter MV implantation prior to clinical trials.

Transcatheter mitral valve interventions

While there are dozens of novel transcatheter mitral devices in various stages of development, they remain years away from FDA approval. The existing approved transcatheter mitral interventions-transcatheter edge to edge repair for primary and secondary mitral regurgitations and transcatheter mitral valve-in-valve and valve-in-ring procedures for failing surgical prostheses-have seen a marked increase in both use and published data over the past several years. Transcatheter edge to edge repair with MitraClip has revolutionized the management of functional mitral regurgitation in heart failure with demonstrated reductions in mortality and heart failure hospitalization and is an appropriate option for patients with primary mitral regurgitation at high or prohibitive surgical risk. In patients with failing surgical mitral prostheses transcatheter mitral valve-in-valve and valve-in-ring procedures are an appealing alternative to repeat mitral valve surgery. Existing data and relevant concerns for these procedures are discussed herein.

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].

Ventricular outflow tract obstruction: An in-silico model to relate the obstruction to hemodynamic quantities in cardiac paediatric patients

BACKGROUND

Right (R) or left (L) ventricular outflow tract (VOT) obstruction can be either a dynamic phenomenon or a congenital anatomic lesion, which requires a prompt and optimal timing of treatment to avoid a pathological ventricular remodelling.

OBJECTIVE

To develop a simple and reliable numerical tool able to relate the R/L obstruction size with the pressure gradient and the cardiac output. To provide indication of the obstruction severity and be of help in the clinical management of patients and designing the surgical treatment for obstruction mitigation.

METHODS

Blood flow across the obstruction is described according to the classical theory of one-dimensional flow, with the obstruction uniquely characterized by its size. Hemodynamics of complete circulation is simulated according to the lumped parameter approach. The case of a 2 years-old baby is reproduced, with the occlusion placed in either the R/ or the L/VOT. Conditions from wide open to almost complete obstruction are reproduced.

RESULTS

Both R/LVOT obstruction in the in-silico model resulted in an increased pressure gradient and a decreased cardiac output, proportional to the severity of the VOT obstruction and dependent on the R/L location of the obstruction itself, as it is clinically observed.

CONCLUSION

The in-silico model of ventricular obstruction which simulates pressure gradient and/or cardiac output agrees with clinical data, and is a first step towards the creation of a tool that can support the clinical management of patients from diagnosis to surgical treatments.

Early outcomes of transatrial mitral valve replacement in severe mitral annular calcification

Objective

Mitral valve replacement (MVR) in the setting of severe mitral annular calcification is a technically challenging operation with increased morbidity and mortality. Transseptal/apical transcatheter MVR (TMVR) in mitral annular calcification has emerged as an option for these cases, although may not be feasible due to anatomical reasons. Transatrial TMVR is a potential treatment option for this subgroup of patients.

Methods

Patients who underwent transatrial TMVR between June 2018 and November 2020 at a single institution were included. Patients were selected by a structural heart team based on their surgical risk, pattern of mitral annular calcification, risk of valve migration, left ventricular outflow obstruction, and paravalvular leak.

Results

A total of 11 patients underwent transatrial TMVR. Mean patient age was 74.2 years and mean Society of Thoracic Surgeons predicted risk of mortality score was 9.1%. All patients had the presence of both mitral stenosis and regurgitation—dominant etiology—was mitral stenosis in 81.2%, and mitral regurgitation in 18.8%. Among patients, 54.5% had a concomitant cardiac procedure. There was no in-hospital or 30-day mortality. Technical success defined by the Mitral Valve Academic Research Consortium was achieved in 90.9% of patients. Postoperative paravalvular leak was mild or less in all patients.

Conclusions

In this series, transatrial TMVR was shown to be a safe and effective treatment option for patients who are high risk for surgical MVR and should be in surgeons' armamentarium in the treatment of this high-risk patient population. Dissemination of safe technique will be critical in the successful conduct of this surgery.

Non coronary applications of cardiac computed tomography: A review

Acquired heart diseases including valvular pathologies and conduction abnormalities, along with coronary artery disease make cardiovascular disease one of the major causes of mortality and morbidity worldwide. Advances in cardiac computed tomography (CCT) have led to markedly improved image quality for assessment of several coronary and noncoronary cardiac abnormalities. With the latest versions of CT scanners, image acquisition can be completed within a few seconds, in a single breath hold and with much less radiation exposure, thus making CT an even more attractive diagnostic tool with its high temporal and excellent spatial resolution. Additional advantages are its noninvasive nature, wide availability, fast image acquisition and ability to provide additional data about the cardiac structure, function, valvular motion, and presence or absence of valvular vegetation, mass or intracardiac thrombus. These factors can result in change in management in many valvular pathologies pre- and post-intervention, and in electrophysiological procedures. The goal of this article is to review applications of cardiac CT in non-coronary indications including valvular assessment, pulmonary vein isolation procedure, and left atrial appendage evaluation for its transcatheter occlusion.

Usefulness of Computed Tomography to Predict Mitral Stenosis After Transcatheter Mitral Valve Edge-to-Edge Repair

Multidetector computed tomography (MDCT) can provide valuable information for preprocedural planning of transcatheter mitral valve interventions. However, no data exists on pre-MDCT parameters predicting high transmitral pressure gradient (TMPG) post-MitraClip procedure. We analyzed the preprocedural MDCTs of 156 consecutive patients with mitral regurgitation undergoing MitraClip implantation at our institution. The mean TMPG was assessed by periprocedural transesophageal and pre-discharge transthoracic echocardiography. MDCT-derived mitral annulus area (MAA), anterior-posterior (AP) and medial-lateral (ML) mitral annulus diameters, and mitral valve orifice area (MVOA) were smaller in patients with mean TMPG ≥5 mmHg than those with mean TMPG <5 mmHg after 1-or 2-clip implantation. Small MAA, AP and ML diameters, and MVOA were moderately correlated with high TMPG post-MitraClip, in which MAA and MVOA had the highest degree of correlation after 1-clip (r = -0.46 both), whereas MAA and ML had the strongest degree of correlation after 2-clip (r = -0.39 both) and at discharge (r = -0.38 both). From the receiver-operating-characteristic curve analyses, no significant differences in the area under the curve were observed among these MDCT parameters for low TMPG after MitraClip implantation, except for those between MAA and AP diameter at discharge (p=0.026). For optimal cutoff values, MAA ≥1100 and ≥1300 mm² had positive predictive values of 89% and 91%, while both MAA ≥750 and ≥900 mm² had negative predictive values of 100%, for mean TMPG <5 mmHg after 1-and 2-clip implantation, respectively. In conclusion, in patients undergoing the MitraClip procedure, preprocedural MDCT parameters are useful to predict postprocedural mitral stenosis.

Unusual Cause of Left Ventricular Outflow Tract Obstruction Following Transcatheter Mitral Valve-in-Ring Replacement

•Causes of LVOT obstruction after transcatheter mitral valve-in-ring replacement. •Unusual cause contributing to obstruction in this case. •Importance of procedural planning to predict and minimize risk for LVOT obstruction. •Role of TEE in diagnosis and in directing therapy when this complication occurs. •Role of noninvasive techniques to prevent and treat LVOT obstruction.

Dynamic nature of the LVOT following transcatheter mitral valve replacement with LAMPOON: new insights from post-procedure imaging

AIMS

To characterize the dynamic nature of the left ventricular outflow tract (LVOT) geometry and flow rate in patients following transcatheter mitral valve replacement (TMVR) with anterior leaflet laceration (LAMPOON) and derive insights to help guide future patient selection.

METHODS AND RESULTS

Time-resolved LVOT geometry and haemodynamics were analysed with post-procedure computed tomography and echocardiography in subjects (N = 19) from the LAMPOON investigational device exemption trial. A novel post hoc definition for LVOT obstruction was employed to account for systolic flow rate and quality of life improvement [obstruction was defined as LVOT gradient >30 mmHg or LVOT effective orifice area (EOA) ≤1.15 cm2]. The neo-LVOT and skirt neo-LVOT were observed to vary substantially in area throughout systole (64 ± 27% and 25 ± 14% change in area, respectively). The peak systolic flow rate occurred most commonly just prior to mid-systole, while minimum neo-LVOT (and skirt neo-LVOT) area occurred most commonly in early-diastole. Subjects with LVOT obstruction (n = 5) had smaller skirt neo-LVOT values across systole. Optimal thresholds for skirt neo-LVOT area were phase-specific (260, 210, 200, and 180 mm2 for early-systole, peak flow, mid-systole, and end-systole, respectively).

CONCLUSION

The LVOT geometry and flow rate exhibit dynamic characteristics following TMVR with LAMPOON. Subjects with LVOT obstruction had smaller skirt neo-LVOT areas across systole. The authors recommend the use of phase-specific threshold values for skirt neo-LVOT area to guide future patient selection for this procedure. LVOT EOA is a 'flow-independent' metric which has the potential to aid in characterizing LVOT obstruction severity.

The role of CT in planning percutaneous structural heart interventions: Where to measure and why

As research continues to demonstrate successes in the use of percutaneous trans-vascular techniques in structural heart intervention, both the subspecialty trained and non-subspecialty trained cardiac imager find themselves performing and reporting larger amounts of information regarding cardiovascular findings. It is therefore imperative that the imager gains understanding and appreciation for how these various measurements are obtained, as well as their implication in a patient's care. Cardiac gated computed tomography (CT) has solidified its role and ability at providing high resolution images that can be used to obtain the key measurements used in structural heart intervention planning. This manuscript aims to provide an overview of what measurements are necessary to report when interpreting CT examinations purposed for structural heart intervention. This includes a review on indications and brief discussion on complications related to these procedures.

A Simplified In Silico Model of Left Ventricular Outflow in Patients After Transcatheter Mitral Valve Replacement with Anterior Leaflet Laceration

In silico modeling has been proposed as a tool to simulate left ventricular (LV) outflow tract (LVOT) obstruction in patients undergoing transcatheter mitral valve replacement (TMVR). This study validated a simplified approach to simulate LV outflow hemodynamics in the setting of TMVR with anterior leaflet laceration, a clinical technique used to mitigate the risk of LVOT obstruction. Personalized, 3-dimensional computational fluid dynamics models were developed from computed tomography images of six patients who underwent TMVR with anterior leaflet laceration. LV outflow hemodynamics were simulated using the patient-specific anatomy and the peak systolic flow rate as boundary conditions. The peak outflow velocity, a clinically relevant hemodynamic metric, was extracted from each simulation (v_sim-peak) and compared with the clinical measurement from Doppler echocardiography (v_clin-peak) for validation. In silico models were successfully developed and implemented for all patients. The pre-processing time was 2 h per model and the simulation could be completed within 3 h. In three patients, the lacerated anterior leaflet exposed open cells of the transcatheter valve to flow. Good agreement was obtained between v_sim-peak and v_clin-peak (r = 0.97, p < 0.01) with average discrepancies of 5 ± 2% and 14 ± 1% for patients with exposed and unexposed cells of the transcatheter valve, respectively. The proposed in silico modeling paradigm therefore simulated LV outflow hemodynamics in a time-efficient manner and demonstrated good agreement with clinical measurements. Future studies should investigate the ability of this paradigm to support clinical applications.

Reoperative Mitral Surgery Versus Transcatheter Mitral Valve Replacement: A Systematic Review

Bioprosthetic mitral structural valve degeneration and failed mitral valve repair (MVr) have traditionally been treated with reoperative mitral valve surgery. Transcatheter mitral valve-in-valve (MVIV) and valve-in-ring (MVIR) replacement are now feasible, but data comparing these approaches are lacking. We sought to compare the outcomes of (1) reoperative mitral valve replacement (redo-MVR) and MVIV for structural valve degeneration, and (2) reoperative mitral valve repair (redo-MVr) or MVR and MVIR for failed MVr. A literature search of PubMed, Embase, and the Cochrane Library was conducted up to July 31, 2020. Thirty-two studies involving 25 832 patients were included. Redo-MVR was required in ≈35% of patients after index surgery at 10 years, with 5% to 15% 30-day mortality. MVIV resulted in >95% procedural success with 30-day and 1-year mortality of 0% to 8% and 11% to 16%, respectively. Recognized complications included left ventricular outflow tract obstruction (0%-6%), valve migration (0%-9%), and residual regurgitation (0%-6%). Comparisons of redo-MVR and MVIV showed no statistically significant differences in mortality (11.3% versus 11.9% at 1 year, P=0.92), albeit higher rates of major bleeding and arrhythmias with redo-MVR. MVIR resulted in 0% to 34% mortality at 1 year, whereas both redo-MVr and MVR for failed repairs were performed with minimal mortality and durable long-term results. MVIV is therefore a viable alternative to redo-MVR for structural valve degeneration, whereas redo-MVr or redo-MVR is preferred for failed MVr given the suboptimal results with MVIR. However, not all patients will be candidates for MVIV/MVIR because anatomical restrictions may preclude transcatheter options from adequately addressing the underlying pathology.

Mitral Valve Annulus Dimensions Assessment with Three-Dimensional Echocardiography Versus Computed Tomography: Implications for Transcatheter Interventions

The aim of this study is to evaluate the agreement between three-dimensional (3D) transesophageal echocardiography (TEE) and multidetector computed tomography (MDCT) for assessing mitral annular (MA) dimensions. A total of 105 patients (79 ± 9 years old, 52% male) who underwent clinically indicated 3D TEE and MDCT feasible for MA geometrical assessment were included. Using dedicated semi-automated postprocessing software, MA geometry, including mitral annular area (MAA), perimeter, septal-lateral (SL) diameter, and inter-trigonal (TT) diameter, was evaluated using 3D TEE and MDCT. Compared to 3D TEE, MAA, perimeter, and SL distance measured on MDCT data were larger (9.9 ± 3.0 vs. 9.3 ± 3.1 cm² for MAA; 115 ± 18 vs. 108 ± 18 mm for perimeter; and 35 ± 5 vs. 32 ± 5 cm for SL distance, all p < 0.001). By contrast, the TT distance was comparable between MDCT and 3D TEE (26 ± 4 vs. 26 ± 4 cm, p = 0.258). The correlations of all the MA dimensions were good to excellent between the two modalities (R = 0.911 for MAA, 0.890 for perimeter, 0.739 for TT distance, and 0.857 for SL distance, respectively, all p < 0.001). This study showed good agreement between 3D TEE- and MDCT-derived MA measurements although MDCT systematically provided larger MAA, perimeter, and SL distance compared with 3D TEE.

Outcome of Patients Having Transcatheter Mitral Valve Implantation for the Treatment of Degenerated Mitral Bioprostheses

Transcatheter mitral valve implantation (TMVI) is at various levels of preclinical investigation and has proven to be more challenging than transcatheter aortic valve implantation due to more complex anatomy. The purpose of this study is to evaluate the short-term and long-term outcomes of high-risk patients who underwent TMVI for degenerated mitral bioprostheses. In this retrospective, observational study, we reviewed data on the first 26 patients with previous surgical mitral valve replacement or repair with annular ring that underwent TMVI using the balloon-expandable heart-valve system at our institution from 2014 to 2019. We reviewed pre/postprocedure echocardiographic data, in-hospital, 30-day data and 1-year outcomes. The indication for TMVI was mitral regurgitation (MR) in 9 patients, mitral stenosis in 9 patients and mixed mitral disease in 8 patients. There was a 100% device implantation success rate and a 96% in-hospital survival rate. Survival was 96% at 30 days and 85% at 1 year. Mean mitral gradient (MMG) improved postprocedure (13.3 mm Hg to 6.8 mm Hg, p <0.0001) and was sustained at 1 year (13.3 mm Hg to 7.2 mm Hg, p <0.0001). MR grade improved postprocedure (3+ to 1+, p <0.0001) and was sustained at 1 year (3+ to 0, p <0.0001). Additionally there was significant 30-day and 1-year improvements in patients' Kansas City Cardiomyopathy Questionnaire score after TMVI (47.8 to 75.7 to 84.0, p = <0.0001). In conclusion, our early experience with treatment of degenerated mitral bioprostheses using TMVI in high-risk patients resulted in significant short-term and sustained long-term improvements in mean mitral gradient, MR and heart failure symptoms.

Transesophageal echocardiography guidance of percutaneous mitral valve replacement in failed annuloplasty ring: A case report

Severe mitral regurgitation and stenosis due to failed mitral annuloplasty ring can be managed with percutaneous mitral valve in ring in high surgical risk patients. A 66-year-old male underwent coronary artery bypass surgery and mitral valve ring annuloplasty 7 years previously. He started to have shortness of breath with minimal effort in the past 2 years. Transthoracic echocardiogram revealed a new severe mitral regurgitation and severe mitral stenosis. The patient was turned down from surgery due to high surgical risk. The transcatheter mitral valve in ring implantation was decided. In this case, there was a low probability of left ventricular outflow tract obstruction. A stiff wire crossed the mitral valve ring and positioned in the left ventricular apex. The Sapien 3 valve size 26 mm (Edwards Lifesciences, Irvine, CA, USA) was positioned to have 80% ventricular and 20% atrial side. Transesophageal echocardiogram evaluation revealed a mean gradient of 5 mmHg. The left ventricular outflow tract (LVOT) had laminar color flow and the mean pressure gradient across LVOT was 1 mmHg. The patient was discharged after 2 days in good condition. At one year follow up, he had no shortness of breath and no rehospitalization. In conclusion, the percutaneous mitral valve in ring is feasible in selected patients. The risk of LVOT obstruction should be assessed carefully before the procedure with a transthoracic and transesophageal echocardiogram. 〈Learning objective: Understand how to guide the mitral valve in ring procedure with a transesophageal echocardiogram and how to avoid left ventricular outflow tract obstruction. Understand how to position the Sapien valve in mitral valve ring.〉.

The Mitral Coaptation to Ventricular Septal Space: Two- and Three-Dimensional Transesophageal Echocardiographic Assessment

OBJECTIVES

To assess the dimensions and changes in the CSEPT (space between the ventricular septum and mitral coaptation point) before and after cardiopulmonary bypass (CPB) and to compare patients with and without aortic valve stenosis (AS) undergoing cardiac surgery.

DESIGN

Retrospective review of intraoperative transesophageal echocardiographic examinations.

SETTING

Single academic medical center.

PARTICIPANTS

The study comprised 91 elective cardiac surgical patients-30 with AS scheduled for aortic valve replacement and 61 without AS (non-AS).

INTERVENTIONS

Two- and 3-dimensional (2D and 3D) analysis of the CSEPT before and after CPB.

MEASUREMENTS AND MAIN RESULTS

Assessment of the CSEPT distances and areas was performed using 2D and 3D imaging before and after CPB. Two-dimensional measures of CSEPT distances were performed using midesophageal 5-chamber and long-axis windows. Three-dimensional measures were performed offline using multiplanar reconstruction. The CSEPT space was smaller after CPB (p < 0.01). Before and after CPB, the midesophageal 5-chamber and long-axis windows were similar to each other, and both were larger than the pre-CPB 3D CSEPT distance. Patients with AS had smaller before and after CPB distances and areas compared with non-AS patients (p < 0.05). The change in CSEPT area in AS patients was 24%.

CONCLUSIONS

The CSEPT space is smaller after CPB and more so for patients with AS undergoing aortic valve replacement. Two-dimensional CEPT distances vary compared with 3D CSEPT distances. Additional study using Doppler analysis will elucidate the added value of 3D assessment of the CSEPT space.

Screening for transcatheter mitral valve replacement: a decision tree algorithm

AIMS

The high frequency of screening failure for anatomical reasons in patients with severe mitral valve regurgitation (MR) is a limiting factor in the screening process for transcatheter mitral valve replacement (TMVR). However, data on optimal patient selection are scarce. The present study aimed to develop a screening algorithm based on TMVR screening data.

METHODS AND RESULTS

A total of 195 screenings for six different TMVR devices were performed in 94 high-risk patients with severe MR. We compared baseline echocardiographic and multislice computed tomography (MSCT) parameters between the subgroups of patients accepted (N=33) and rejected for TMVR (N=61). Reasons for screening failure were assessed, and a decision tree algorithm was statistically derived. Reasons for screening failure were small LV dimensions (30.6%), small (7.5%) or large (22.5%) annular size, potential risk of LVOT obstruction (22.0%) or mitral annulus calcification (15.6%). A four-step decision tree algorithm to assess TMVR eligibility was developed resulting in an AUC of 0.80 (95% CI: 0.71, 0.89, p<0.0001).

CONCLUSIONS

This study presents the first screening algorithm to assess anatomical eligibility for TMVR in patients with severe MR, based on simple MSCT criteria. Given the high rate of TMVR screening failure, this algorithm may facilitate the identification of potential TMVR candidates.

Balloon assisted translocation of the mitral anterior leaflet to prevent left ventricular outflow obstruction (BATMAN): A novel technique for patients undergoing transcatheter mitral valve replacement

INTRODUCTION

Transcatheter mitral valve replacement (TMVR) is an option for patients at high risk for mitral valve replacement or repair via sternotomy or left thoracotomy approach. TMVR carries up to 22% risk of left ventricular outflow tract (LVOT) obstruction. Severe LVOT obstruction can have devastating hemodynamic and clinical consequences.

HYPOTHESIS

We previously presented a novel technique to prevent LVOT obstruction during transapical retrograde mitral valve replacement, by penetrating and ballooning the anterior mitral leaflet (AML), resulting in creation of a "hole" and posterior translocation of AML, then deploying the valve.

METHODS

Three patients underwent TMVR at Saint Louis University for severe mitral regurgitation after being deemed too high risk for surgery, and not candidates for a Mitra-clip procedure. These patients were deemed to be at risk for LVOT obstruction based on the preprocedural evaluation. Via transapical approach, a needle was advanced "through," perforating the AML and wire was placed in the left atrium. Over the wire, an 20-mm valvuloplasty balloon was positioned "within" the anterior leaflet and inflated leading to translocation of the AMVL. Then the valve was deployed.

RESULTS

This novel technique has been performed on three patients at our institution. Sapien S3 transcatheter valves were used in all three patients, with 100% procedural success rate. Intraoperative TEE demonstrated no significant LVOT obstruction, cardiopulmonary bypass time was 42-44 min.

CONCLUSION

The balloon assisted translocation of the mitral anterior leaflet to prevent left ventricular outflow obstruction technique described here may offer the option of transcatheter mitral valve implantation in patients at high risk of LVOT obstruction. A variation of this technique to allow application in cases with transseptal approach is under investigation.

Predictors of adverse outcomes after transcatheter mitral valve replacement

Introduction: Transcatheter mitral valve replacement (TMVR) is still a recent technology with numerous unknowns but also great promises. The risk of complications reported in observational studies have limited its adoption by interventional cardiology and surgical communities. Areas covered: Some of the major setbacks of TMVR are complications related to the devices and those related to the pathway. Device-related complications include left ventricle outflow tract (LVOT) obstruction, transcatheter heart valve (THV) dislocation or embolization, thrombosis, and stroke. The transapical approach currently remains the main pathway for TMVR but is associated with high risk of major bleeding and residual apical myocardial scarring. Complication prediction and prevention seem possible. Device-related complication prediction is based on pre-operative imaging including multi-slice computed tomography with 3-dimensional reconstructions and echocardiography which allow LVOT obstruction prediction and appropriate sizing aiming at avoiding dislocation. Industry should aim at the development of transfemoral delivery systems. Nevertheless, several recent feasibility observational studies suggested acceptable safety and efficacy of transcatheter mitral valve replacement. Expert opinion: TMVR complications and transapical delivery are some of the main setbacks which need to be addressed for TMVR to be adopted for broad clinical use.

Transcatheter Mitral Valve Implantation with the Medtronic Intrepid™ Transcatheter Mitral Valve Replacement System

Mitral regurgitation is the most prevalent yet undertreated valvulopathy despite its adverse prognosis. With the emergence of transcatheter mitral interventions, the potential for this huge unmet disease burden to be addressed may finally be realized. Medtronic Intrepid™ Transcatheter Mitral Valve Replacement System represents one of several novel solutions. Based on early data from the pilot study, its efficacy and clinical utility is currently being tested against the mainstay treatment of surgical mitral valve replacement in a randomized trial. While there remain significant challenges before transcatheter mitral intervention can become part of the routine treatment algorithm, the authors are optimistic that transcatheter mitral valve repair and intervention have the potential in revolutionizing the management of severe symptomatic mitral regurgitation.

Mitral Annular Calcification and Calcific Mitral Stenosis: Therapeutic Challenges and Considerations

PURPOSE OF REVIEW

Mitral annular calcification (MAC) and associated calcific mitral stenosis (MS) are frequent in the aging population, although optimal management remains debated and outcomes are poor. This article summarizes challenges in the diagnosis and therapy of calcific MS, the indications for valve intervention, procedural concerns, and emerging treatment options.

RECENT FINDINGS

Surgical mitral valve replacement is the procedure of choice in symptomatic patients at acceptable surgical risk, with transcatheter mitral valve replacement (TMVR) being evaluated in clinical trials as an alternative for patients at prohibitive surgical risk. Significant challenges exist with the currently available technology and outcomes have been suboptimal. Optimizing the patient-selection process by using multimodality imaging tools has proven to be essential. MAC and calcific MS is an increasingly prevalent, challenging issue with poor outcomes. While surgical valve replacement can be performed in patients with acceptable surgical risk, TMVR can be considered for patients at higher risk. Clinical trials are underway to optimize outcomes. Dedicated device designs and techniques to minimize risk of left ventricular outflow tract obstruction, paravalvular leakage, and device embolization are to be awaited.

Percutaneous Techniques, Limitations and Challenges for the Failed Surgical Mitral Intervention

The advent of percutaneous therapies has significantly altered therapeutic options for patients with valvular heart disease. Building on the success of transcatheter aortic valve replacement, both expanded indications and purpose-built devices are now being used to address percutaneous approaches for mitral valve pathology. While surgical mitral valve repair remains the gold standard for addressing significant mitral valve pathology, there has been a progressive increase in the utilization of bioprosthetic valves despite their limited lifespan. The risks of reoperation to address mitral valve repair failure or bioprosthetic valve dysfunction is not insignificant. In light of the aging population and the potential for significant associated comorbidities, less invasive alternative techniques hold particular appeal. Utilization of commercially available transcatheter aortic valve replacement valves for failed surgical valves has been shown to have better short-term mortality than would be predicted for open reoperation. As a result, the US Food and Drug Administration approved the utilization of transcatheter mitral valve-in-valve replacement for the failed bioprosthetic valve in high surgical risk patients. Despite the favorable outcomes, transcatheter mitral valve-in-valve is not without procedural challenges and potential complications including malpositioning, embolization, paravalvular leak, and outflow tract obstruction. Awareness of these challenges, mitigation strategies, and therapeutic options is imperative to optimizing outcomes in this high-risk patient population.

Early clinical results with the Tendyne transcatheter mitral valve replacement system

Transcatheter mitral valve replacement is an emerging technology for the treatment of mitral valve regurgitation. Numerous devices are in development and in various stages of clinical investigation. The Tendyne system (Tendyne Holdings, LLC, a subsidiary of Abbott Vascular, Roseville, Minnesota) is a fully repositionable and retrievable, transapical transcatheter mitral valve replacement platform. The results of the early feasibility studies in the U.S. are highly encouraging and a pivotal randomized trial is underway. The Tendyne transcatheter mitral valve replacement valve may prove to be a safe, less invasive approach to treatment of mitral valve disease.

Multimodality imaging for the quantitative assessment of mitral regurgitation

The natural history of mitral regurgitation (MR) results in significant morbidity and mortality. Innovations in non-invasive imaging have provided new insights into the pathophysiology and quantification of MR, in addition to early detection of left ventricular (LV) dysfunction and prognostic assessment in asymptomatic patients. Transthoracic (TTE) and transesophageal (TOE) echocardiography are the mainstay for diagnosis, assessment and serial surveillance. However, the advance from 2D to 3D imaging leads to improved assessment and characterization of mitral valve (MV) disease. Cardiovascular magnetic resonance (CMR) is increasingly used for MR quantitation and can provide an alternative imaging method if echocardiography is suboptimal or inconclusive. Other techniques such as exercise echocardiography, tissue Doppler imaging and speckle-tracking echocardiography can further offer complementary information on prognosis. This review summarises the current evidence for state-of-the-art cardiovascular imaging for the investigation of MR. Whilst advanced echocardiographic techniques are superior in the evaluation of complex MV anatomy, CMR appears the most accurate technique for the quantification of MR severity. Integration of multimodality imaging for the assessment of MR utilises the advantages of each imaging technique and offers the most comprehensive assessment of MR.