Dynamic 3-dimensional echocardiographic assessment of mitral annular geometry in patients with functional mitral regurgitation

Euclidean and Shape-Based Analysis of the Dynamic Mitral Annulus in Children using a Novel Open-Source Framework

BACKGROUND

The dynamic shape of the normal adult mitral annulus has been shown to be important to mitral valve function. However, annular dynamics of the healthy mitral valve in children have yet to be explored. The aim of this study was to model and quantify the shape and major modes of variation of pediatric mitral valve annuli in four phases of the cardiac cycle using transthoracic echocardiography.

METHODS

The mitral valve annuli of 100 children and young adults with normal findings on three-dimensional echocardiography were modeled in four different cardiac phases using the SlicerHeart extension for 3D Slicer. Annular metrics were quantified using SlicerHeart, and optimal normalization to body surface area was explored. Mean annular shapes and the principal components of variation were computed using custom code implemented in a new SlicerHeart module (Annulus Shape Analyzer). Shape was regressed over metrics of age and body surface area, and mean shapes for five age-stratified groups were generated.

RESULTS

The ratio of annular height to commissural width of the mitral valve ("saddle shape") changed significantly throughout age for systolic phases (P < .001) but within a narrow range (median range, 0.20-0.25). Annular metrics changed statistically significantly between the diastolic and systolic phases of the cardiac cycle. Visually, the annular shape was maintained with respect to age and body surface area. Principal-component analysis revealed that the pediatric mitral annulus varies primarily in size (mode 1), ratio of annular height to commissural width (mode 2), and sphericity (mode 3).

CONCLUSIONS

The saddle-shaped mitral annulus is maintained throughout childhood but varies significantly throughout the cardiac cycle. The major modes of variation in the pediatric mitral annulus are due to size, ratio of annular height to commissural width, and sphericity. The generation of age- and size-specific mitral annular shapes may inform the development of appropriately scaled absorbable or expandable mitral annuloplasty rings for children.

Regional geometric differences between regurgitant and non-regurgitant mitral valves in patients with coronary artery disease

OBJECTIVE

Demonstrate that regional geometric differences exist between regurgitant and non-regurgitant mitral valves (MV's) in patients with coronary artery disease and due to the heterogenous and regional nature of ischemic remodeling in patients with coronary artery disease (CAD), that the available anatomical reserve and likelihood of developing mitral regurgitation (MR) is variable in non-regurgitant MV's in patients with CAD.

METHODS

In this retrospective, observational study intraoperative three-dimensional transesophageal echocardiographic data was analyzed in patients undergoing coronary revascularization with MR (IMR group) and without MR (NMR group). Regional geometric differences between both groups were assessed and MV reserve which was defined as the increase in antero-posterior (AP) annular diameter from baseline that would lead to coaptation failure was calculated in three zones of the MV from antero-lateral (zone 1), middle (zone 2), and posteromedial (zone 3).

MEASUREMENTS AND MAIN RESULTS

There were 31 patients in the IMR group and 93 patients in the NMR group. Multiple regional geometric differences existed between both groups. Most significantly patients in the NMR group had significantly larger coaptation length and MV reserve than the IMR group in zones 1 (p-value = .005, .049) and 2 (p-value = .00, .00), comparable between the two groups in zone 3 (p-value = .436, .513). Depletion of the MV reserve was associated with posterior displacement of the coaptation point in zones 2 and 3.

CONCLUSIONS

There are significant regional geometric differences between regurgitant and non-regurgitant MV's in patients with coronary artery disease. Due to regional variations in available anatomical reserve and the risk of coaptation failure in patients with CAD, absence of MR is not synonymous with normal MV function.

The Impact of Atrial Fibrillation on All Heart Chambers Remodeling and Function in Patients with Dilated Cardiomyopathy-A Two- and Three-Dimensional Echocardiography Study

Atrial fibrillation is frequently seen in patients with dilated cardiomyopathy (DCM), and its presence impacts the function of the heart, with clinical and prognostic consequences. In this prospective single-center study, we aimed to assess the impact of atrial fibrillation on cardiac structure and function, using comprehensive two- and three-dimensional echocardiography. We included 41 patients with DCM and persistent or permanent atrial fibrillation (38 male, age 58.8 ± 11 years), as well as 47 patients with DCM and in sinus rhythm (35 male, age 58 ± 12.5 years). Cardiac chambers and mitral and tricuspid valves' structure and function were assessed via standard two-dimensional, speckle-tracking, and three-dimensional echocardiography (3DE). Patients with DCM and atrial fibrillation had a more impaired left ventricular global longitudinal strain, higher 3DE left atrial volumes, and reduced function compared to patients in sinus rhythm in the presence of similar left ventricle volumes. Mitral annulus configuration was altered in atrial fibrillation DCM patients. Also, right heart volumes were larger, with more severe atrial and ventricular dysfunction, despite similar estimated pulmonary artery pressures and severity of tricuspid regurgitation. Using advanced echocardiography techniques, we demonstrated that atrial fibrillation induces significant remodeling in all heart chambers.

The effects of leaflet material properties on the simulated function of regurgitant mitral valves

Advances in three-dimensional imaging provide the ability to construct and analyze finite element (FE) models to evaluate the biomechanical behavior and function of atrioventricular valves. However, while obtaining patient-specific valve geometry is now possible, non-invasive measurement of patient-specific leaflet material properties remains nearly impossible. Both valve geometry and tissue properties play a significant role in governing valve dynamics, leading to the central question of whether clinically relevant insights can be attained from FE analysis of atrioventricular valves without precise knowledge of tissue properties. As such we investigated (1) the influence of tissue extensibility and (2) the effects of constitutive model parameters and leaflet thickness on simulated valve function and mechanics. We compared metrics of valve function (e.g., leaflet coaptation and regurgitant orifice area) and mechanics (e.g., stress and strain) across one normal and three regurgitant mitral valve (MV) models with common mechanisms of regurgitation (annular dilation, leaflet prolapse, leaflet tethering) of both moderate and severe degree. We developed a novel fully-automated approach to accurately quantify regurgitant orifice areas of complex valve geometries. We found that the relative ordering of the mechanical and functional metrics was maintained across a group of valves using material properties up to 15% softer than the representative adult mitral constitutive model. Our findings suggest that FE simulations can be used to qualitatively compare how differences and alterations in valve structure affect relative atrioventricular valve function even in populations where material properties are not precisely known.

The Effects of leaflet material properties on the simulated function of regurgitant mitral valves

Advances in three-dimensional imaging provide the ability to construct and analyze finite element (FE) models to evaluate the biomechanical behavior and function of atrioventricular valves. However, while obtaining patient-specific valve geometry is now possible, non-invasive measurement of patient-specific leaflet material properties remains nearly impossible. Both valve geometry and tissue properties play a significant role in governing valve dynamics, leading to the central question of whether clinically relevant insights can be attained from FE analysis of atrioventricular valves without precise knowledge of tissue properties. As such we investigated 1) the influence of tissue extensibility and 2) the effects of constitutive model parameters and leaflet thickness on simulated valve function and mechanics. We compared metrics of valve function (e.g., leaflet coaptation and regurgitant orifice area) and mechanics (e.g., stress and strain) across one normal and three regurgitant mitral valve (MV) models with common mechanisms of regurgitation (annular dilation, leaflet prolapse, leaflet tethering) of both moderate and severe degree. We developed a novel fully-automated approach to accurately quantify regurgitant orifice areas of complex valve geometries. We found that the relative ordering of the mechanical and functional metrics was maintained across a group of valves using material properties up to 15% softer than the representative adult mitral constitutive model. Our findings suggest that FE simulations can be used to qualitatively compare how differences and alterations in valve structure affect relative atrioventricular valve function even in populations where material properties are not precisely known.

Three-dimensional cardiac computed tomography compared with autopsied material for the assessment of the mitral valve

To compare the morphometrical features of non-diseased mitral valves imaged in three-dimensional (3D) cardiac computed tomography with those analyzed macroscopically in autopsied healthy human hearts. A total of 51 cardiac computed tomography scans and 120 adult autopsied human hearts without cardiovascular disease were examined. The 3D reconstruction and visualization software (Mimics Innovation Suite 22, Materialise) was used for heart chambers semi-automatic segmentation and myocardial manual segmentation to visualize a 3D structure of the mitral valve complex and to perform all measurements. Direct comparison of corresponding mitral valve parameters revealed significant differences between obtained results. Significantly larger intercommisural diameter, aorto-mural diameter, and perimeter of the mitral annulus were observed in tomographic scans (all p < 0.0001). However, the intercommissural/aorto-mural diameter ratio showed comparable values for both groups. Nevertheless, the size of anterior mitral leaflet was higher in autopsied material. The height of the P2 scallops was the only parameter that show no significant difference between two groups (p = 0.3). The use of 3D postprocessing algorithms provides a very accurate image of the mitral valve structure, which could be useful for the precise non-invasive assessment of mitral valve size and structure. Three-dimensional contrast enhanced cardiac computed tomography significantly overestimates the measurements of the mitral annulus compared to postmortem analysis.

Geometric Indices for Predicting Ischemic Mitral Regurgitation: Correlation of Mitral Valve Coaptation Area With Tenting Height, Tenting Area and Tenting Volume

OBJECTIVES

Ischemic remodeling of the left ventricle in patients with coronary artery disease (CAD) results in geometric changes of the mitral valve (MV) apparatus, leading to reduced MV leaflet coaptation. Although the calculation of the coaptation area has value in assessing the effects of left ventricular remodeling on the MV, it is difficult and time-consuming to measure. In this study the authors hypothesized that the tenting volume (TV) would have a greater association with coaptation area than tenting height (TH) or tenting area (TA).

DESIGN

A retrospective review.

SETTING

A single tertiary-care academic hospital.

PARTICIPANTS

There were 145 adult patients who underwent coronary artery bypass graft surgery between April 2018 and July 2020.

MEASUREMENTS AND MAIN RESULTS

Intraoperative 2- and 3-dimensional transesophageal echocardiographic studies were obtained in the precardiopulmonary bypass period. Offline analysis was used to obtain TH, TA, TV and coaptation area for each patient. Correlation between the coaptation area and the TH, TA, and TV was conducted using Pearson's correlation. The median age of the population was 68.0 years (61.0-73.3), the body mass index was 29.0 kg/m² (25.7-33.5), and 17.8% were females. Increases in TV were the most reliable predictor of decreases in coaptation area (R² = 0.75) followed by TA (R² = 0.48) and TH (R² = 0.47).

CONCLUSION

As a representative of the complete topography of the MV, the authors' study demonstrated that in patients with CAD, TV has a greater negative correlation with coaptation area as compared to TH or TA.

Disproportionate Mitral Regurgitation Determines Survival in Acute Heart Failure

Objectives: To assess the prevalence and impact of mitral regurgitation (MR) on survival in patients presenting to hospital in acute heart failure (AHF) using traditional echocardiographic assessment alongside more novel indices of proportionality.

Background: It remains unclear if the severity of MR plays a significant role in determining outcomes in AHF. There is also uncertainty as to the clinical relevance of indexing MR to left ventricular volumes. This concept of disproportionality has not been assessed in AHF.

Methods: A total of 418 consecutive patients presenting in AHF over 12 months were recruited and followed up for 2 years. MR was quantitatively assessed within 24 h of recruitment. Standard proximal isovelocity surface area (PISA) and a novel proportionality index of effective regurgitant orifice/left ventricular end-diastolic volume (ERO/LVEDV) >0.14 mm²/ml were used to identify severe and disproportionate MR.

Results: Every patient had MR. About 331/418 (78.9%) patients were quantifiable by PISA. About 165/418 (39.5%) patients displayed significant MR. A larger cohort displayed disproportionate MR defined by either a proportionality index using ERO/LVEDV > 0.14 mm²/ml or regurgitant volumes/LVEDV > 0.2 [217/331 (65.6%) and 222/345 (64.3%), respectively]. The LVEDV was enlarged in significant MR−129.5 ± 58.95 vs. 100.0 ± 49.91 ml in mild, [p < 0.0001], but remained within the normal range. Significant MR was associated with a greater mortality at 2 years {44.2 vs. 34.8% in mild MR [hazard ratio (HR) 1.39; 95% CI: 1.01–1.92, p = 0.04]}, which persisted with adjustment for comorbid conditions (HR; 1.43; 95% CI: 1.04–1.97, p = 0.03). Disproportionate MR defined by ERO/LVEDV >0.14 mm²/ml was also associated with worse outcome [42.4 vs. 28.3% (HR 1.62; 95% CI 1.12–2.34, p = 0.01)].

Conclusions: MR was a universal feature in AHF and determines outcome in significant cases. Furthermore, disproportionate MR, defined either by effective regurgitant orifice (ERO) or volumetrically, is associated with a worse prognosis despite the absence of adverse left ventricular (LV) remodeling. These findings outline the importance of adjusting acute volume overload to LV volumes and call for a review of the current standards of MR assessment.

Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT02728739, identifier NCT02728739.

Atrial fibrillation is associated with large beat-to-beat variability in mitral and tricuspid annulus dimensions

AIMS

Beat-to-beat variability in cycle length is well-known in atrial fibrillation (Afib); whether this also translates to variability in annulus size remains unknown. Defining annulus maximal size in Afib is critical for accurate selection of percutaneous devices given the frequent association with mitral and tricuspid valve diseases.

METHODS AND RESULTS

Images were obtained from 170 patients undergoing 3D echocardiography [100 (50 sinus rhythm (SR) and 50 Afib) for mitral annulus (MA) and 70 (35 SR and 35 Afib) for tricuspid annulus (TA)]. Images were analysed for differences in annular dynamics with a commercially available software. Number of cardiac cycles analysed was 567 in mitral valve and 346 in tricuspid valve. Median absolute difference in maximal MA area over four to six cycles was 1.8 cm2 (range 0.5-5.2 cm2) in Afib vs. 0.8 cm2 (range 0.1-2.9 cm2) in SR, P < 0.001. Maximal MA area was observed within 30-70% of the R-R interval in 81% of cardiac cycles in SR and in 73% of cycles in Afib. Median absolute difference in maximal TA area over four to six cycles was 1.4 cm2 (range 0.5-3.6 cm2) in Afib vs. 0.7 cm2 (range 0.3-1.7 cm2) in SR, P < 0.001. Maximal TA area was observed within 60-100% of the R-R interval in 81% of cardiac cycles in SR, but only in 49% of cycles in Afib.

CONCLUSION

MA and TA reach maximal size within a broad time interval centred around end-systole and end-diastole, respectively, with significant beat-to-beat variability. Afib leads to a larger beat-to-beat variability in both timing of occurrence and values of annulus size than in SR.

Ex Vivo Model of Functional Mitral Regurgitation Using Deer Hearts

Transcatheter therapies are emerging for functional mitral regurgitation (FMR) treatment, however there is lack of pathological models for their preclinical assessment. We investigated the applicability of deer hearts for this purpose.

8 whole deer hearts were housed in a pulsatile flow bench. At baseline, all mitral valves featured normal coaptation. The pathological state was induced by 60-minutes intraventricular constant pressurization. It caused mitral annulus dilation (antero-posterior diameter increase from 31.8 ± 5.6 mm to 39.5 ± 4.9 mm, p = 0.001), leaflets tethering (maximal tenting height increase from 7.3 ± 2.5 mm to 12.7 ± 3.4 mm, p < 0.001) and left ventricular diameter increase (from 67.8 ± 7.5 mm to 79.4 ± 6.5 mm, p = 0.004). These geometrical reconfigurations led to restricted mitral valve leaflets motion and leaflet coaptation loss. Preliminary feasibility assessment of two FMR treatments was performed in the developed model.

Deer hearts showed ability to dilate under constant pressurization and have potential to be used for realistic preclinical research of novel FMR therapies.

Transcatheter aortic valve implantation and its impact on mitral valve geometry and function

BACKGROUND

The aim of this study was to evaluate the impact of transcatheter aortic valve implantation (TAVI) on mitral valve geometry and function.

METHODS

Eighty-four patients underwent TAVI. Forty-four (52%) patients received a balloon-expandable valve and 40 (48%) were implanted with a self-expandable valve. All patients underwent three-dimensional-volumetric transesophageal echocardiography of the mitral valve before and immediately after TAVI. A dedicated software was used for assisted semiautomatic measurement of mitral annular geometry.

RESULTS

During systole, the anterior to posterior (AP) diameter was significantly reduced after the procedure (3.4 ± 0.5 cm vs 3.2 ± 0.5 cm; P < .05). The mitral annular area (10.8 ± 2.8cm² vs 9.9 ± 2.6cm² ; P < .05) as well as the tenting area (1.6 ± 0.7 cm² vs 1.2 ± 0.6 cm² ; P < .001) measured at mid-systole were reduced after TAVI. Diastolic measures were similar. Patients treated with balloon-expandable valves showed a significantly larger reduction in the AP diameter compared to self-expandable valves (-0.25 cm vs -0.11 cm; P < .05). The reduction of the annular area was higher in the balloon-expandable group (-1.2 ± 1.59 vs -0.22 ± 1.41; P < .05). Grade of mitral regurgitation did improve or remained stable after TAVI.

CONCLUSION

TAVI significantly impacts the mitral valve and mitral annular geometry and morphology. The choice of the prosthesis (balloon- vs self-expandable) may be relevant for those changes.

Relation of Mitral Annulus and Left Atrial Dysfunction to the Severity of Functional Mitral Regurgitation in Patients with Dilated Cardiomyopathy

METHODS

56 patients (58 ± 17 years, 42 men) with DCM and FMR and 52 controls, prospectively enrolled, underwent 3DTTE dedicated for mitral valve (MV), LA, and left ventricle (LV) quantitative analysis.

RESULTS

Patients with FMR vs. controls presented increased MA size and sphericity during the entire systole, whereas MA fractional area change (MAFAC) and MA displacement were decreased (15 ± 5 vs. 28 ± 5%; and 5 ± 3 vs. 10 ± 2 mm, p < 0.001). In patients with moderate/severe FMR, MA diameters correlated with PISA radius, EROA, and regurgitant volume (Rvol), as also did the MA area (with PISA radius, EROA, and Rvol: r = 0.48, r = 0.58, and r = 0.47, p < 0.05). MAFAC correlated inversely with EROA and Rvol (r = -0.32 and r = -0.35, p < 0.05), with both active and total LA emptying fractions and with LV ejection fraction as well. In a stepwise multivariate regression model, decreased MAFAC and increased LA volume independently predicted patients with severe FMR.

CONCLUSIONS

Patients with DCM and FMR have MA geometry remodeling and contractile dysfunction, correlated with the severity of FMR. MA contractile dysfunction correlated with both LA and left LV pumps dysfunctions and predicted patients with severe FMR. Our results provide new insights that might help with better selection of patients for MV transcatheter procedures.

Tricuspid valve geometry in patients with functional tricuspid regurgitation: A three-dimensional echocardiographic study

INTRODUCTION

Tricuspid valve (TV) has a complex anatomy causing some difficulties in echocardiographic evaluation. In this study, we sought to assess the geometry of TV in patients with functional tricuspid regurgitation (TR) by the implementation of 2- and 3-dimennsional (2D and 3D) echocardiography.

METHODS

In a case-control study, the geometrical features of TV were evaluated in forty patients with functional TR using echocardiographic examinations, and those data compared with twenty-five age- and sex-matched healthy individuals.

RESULTS

The mean age of patients was 50 ± 12 years, and 75% were female. All echocardiographic features of TV geometry were significantly greater in TR compared to control group. The 3D evaluation of TV annulus showed that the annulus shape was more circular in the TR compared to the control group. When compared patients with moderate and severe TR, there was a significant difference between groups regarding the size of the TV septolateral annulus diameter (3.5 ± 0.4 vs 3.9 ± 0.7 cm; P = .048), and the angle between mitral valve and TV annuluses (12.5 ± 4.3 vs 17 ± 9º; P = .048). Tenting areas measured by 2D echocardiography and obtained by TomTec software were significantly greater in severe TR compared to moderate TR group. The diameter of TV by 2D echocardiography was significantly higher in atrial fibrillation than that in sinus rhythm group among patients with TR.

CONCLUSIONS

The implementation of 3D echocardiography is useful in the determination of TV geometry in patients with functional TR. The accurate evaluation of anatomical features of TV might provide valuable tools in the evaluation of patients with functional TR.

MITT: Medical Image Tracking Toolbox

Over the years, medical image tracking has gained considerable attention from both medical and research communities due to its widespread utility in a multitude of clinical applications, from functional assessment during diagnosis and therapy planning to structure tracking or image fusion during image-guided interventions. Despite the ever-increasing number of image tracking methods available, most still consist of independent implementations with specific target applications, lacking the versatility to deal with distinct end-goals without the need for methodological tailoring and/or exhaustive tuning of numerous parameters. With this in mind, we have developed the medical image tracking toolbox (MITT)-a software package designed to ease customization of image tracking solutions in the medical field. While its workflow principles make it suitable to work with 2-D or 3-D image sequences, its modules offer versatility to set up computationally efficient tracking solutions, even for users with limited programming skills. MITT is implemented in both C/C++ and MATLAB, including several variants of an object-based image tracking algorithm and allowing to track multiple types of objects (i.e., contours, multi-contours, surfaces, and multi-surfaces) with several customization features. In this paper, the toolbox is presented, its features discussed, and illustrative examples of its usage in the cardiology field provided, demonstrating its versatility, simplicity, and time efficiency.

Vendor-Neutral Right Ventricular Strain Measurement

OBJECTIVE

To test the feasibility and reliability of using a vendor-neutral platform to evaluate right ventricular (RV) strain. Reliability was determined by comparing intra- and inter-observer variability between RV strain assessments. The secondary objective was to assess strain's correlation with conventional RV functional parameters to evaluate its feasibility as a RV systolic functional assessment tool.

DESIGN

This is a retrospective study.

SETTING

Tertiary hospital.

PARTICIPANTS

A total of 15 patients who underwent elective coronary artery bypass graft surgery were selected for inclusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Images obtained during routine, intraoperative, two-dimensional transesophageal echocardiography (2D TEE) were assessed for longitudinal strain (LS) and conventional parameters, including fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), Doppler tissue imaging (DTI)-derived tricuspid lateral annular systolic velocity wave (S'), and RV dimensions using vendor-neutral software. There was good to excellent intra- and inter-observer reproducibility (intraclass correlation coefficient [ICC] from 0.75 to 1.00) with the exception of basal free wall longitudinal strain (FWLS) (for intra- and inter-observer reproducibility, ICC = 0.670 and 0.749, respectively). FWLS and global longitudinal strain (GLS) showed moderate to strong positive correlation with FAC, TAPSE, and S' (correlation coefficients from 0.667 to 0.721).

CONCLUSION

It is feasible to assess RV strain across multiple platforms in a reproducible and reliable fashion. Furthermore, RV strain demonstrated good correlation with conventional RV functional parameters, suggesting its feasibility as a sensitive RV function assessment tool.

Modelling of Lesions Associated with Functional Mitral Regurgitation in an Ex Vivo Platform

Functional mitral regurgitation (FMR) is a complex pathology involving valvular and subvalvular structures reconfiguration, and its treatment is considered challenging. There is a lack of experimental models allowing for reliable preclinical FMR treatments' evaluation in a realistic setting. A novel approach to simulate FMR was developed and incorporated into an ex vivo passive beating heart platform. FMR was obtained by dilating the mitral annulus (MA) mainly in the antero-posterior direction and displacing the papillary muscles (PMs) apically and laterally by ad hoc designed and 3D printed dilation and displacing devices. It caused hemodynamic and valve morphology alterations. Isolated MA dilation (MAD) led to significantly increased antero-posterior distance (A-P) and decreased coaptation height (CH), tenting area (TA) and systolic leaflets angulation, resembling clinically recognized type I of mitral regurgitation with normal leaflet motion. Whereas concomitant MAD with PM displacement caused an increase in A-P, TA, CH. This geometrical configuration replicated typical determinants of type IIIb lesion with restricted leaflet motion. The proposed methods provided a realistic and repeatable ex vivo FMR model featuring two lesions clinically associated with the pathology. It bears a promise to be successfully utilized in preclinical studies, clinical training and medical education.

Three-Dimensional Mitral Valve Morphology and Age-Related Trends in Children and Young Adults with Structurally Normal Hearts Using Transthoracic Echocardiography

BACKGROUND

The mitral valve has a complex three-dimensional (3D) morphology that is incompletely described by two-dimensional echocardiography (echo). Three-dimensional echo provides a more robust tool to analyze the mitral valve. The shape of the mitral annulus and leaflets, and differences with age, have not been described by 3D echo in normal children. Our objective was to characterize and quantify the 3D mitral valve morphology in children with normal transthoracic echocardiograms over a broad spectrum of age and to identify differences in valve shape with age.

METHODS

Three-dimensional midsystolic mitral valve models were constructed in 100 children and young adults with normal echocardiograms using 3D transthoracic images. Annular and leaflet metrics were quantified and regression equations were prepared. Interuser and intrauser variability was measured.

RESULTS

Two hundred fifty patients, from neonate to young adult, were retrospectively reviewed to obtain 100 evaluable patients (40% evaluable). The annular height to commissural width ratio of the mitral valve ("saddle shape") was preserved across age (median 24.3, IQR 21.8-28.1). Three-dimensional mitral valve area, length, and volume parameters were linearly related to body surface area (P < .001). The ratio of anterior to posterior leaflet length and posterior leaflet angle increased with body surface area (P = .0004 and .002, respectively) suggesting posterior movement of the coaptation line. Two-dimensional lateral annular diameter underestimated 3D lateral annular metrics (P < .001, mean difference 20-22%) but was highly correlated (R > 0.87, P < .001). Interuser and intrauser variability were acceptable.

CONCLUSIONS

Assessment of 3D mitral valve morphology in children is possible in a modern clinical pediatric echocardiography laboratory using transthoracic images, although further optimization of imaging is needed. The saddle shape of the mitral annulus was preserved across age and size. Most mitral valve parameters increased linearly with patient size. Further investigation is warranted to explore changes in valve morphology in the pediatric population in health and with disease.

Regional Heterogeneity in the Mitral Valve Apparatus in Patients With Ischemic Mitral Regurgitation

BACKGROUND

Apical displacement of the coaptation point of the mitral valve (MV) in response to ischemic mitral regurgitation (IMR) represents remodeling of the MV apparatus. Whereas it implies chronicity, it lacks specificity in discriminating normal from a significantly remodeled MV apparatus. Regional aspects of MV remodeling have shown superior value over global remodeling in predicting recurrence after MV repair for IMR. Quite possibly, presence of specific regional changes in MV geometry that are unique to chronic IMR patients could also be used to diagnose the presence and track progression of remodeling. Knowledge of these changes in MV apparatus in patients with IMR can possibly be used to identify patients for surgical intervention before irreversible remodeling occurs.

METHODS

Three-dimensional transesophageal echocardiographic data were collected from patients who underwent MV surgery for IMR (IMR group, n = 66), and from patients with normal valvular and biventricular function (control group, n = 10). The acquired data of the MV were geometrically analyzed to make regional comparisons between the IMR and the control group to identify measurements that reliably differentiate normal from remodeled MVs.

RESULTS

Lengthening of the middle potion of the anterior annulus (A2 regional perimeter: 11.149 mm versus 9.798 mm, p = 0.0041), larger nonplanarity angle (147.985 versus 140.720 degrees, p = 0.0459), and increased tenting angle of the posteromedial scallop of the posterior leaflet (P3 tenting angle: 44.354 versus 40.461 degrees, p = 0.0435) were sufficient in differentiating between IMR and the control group.

CONCLUSIONS

Specific three-dimensional changes in MV geometry can be used to reliably identify a significantly remodeled valve apparatus.

Assessment of mitral valve geometric deformity in patients with ischemic heart disease using three-dimensional echocardiography

BACKGROUND

A full understanding of the geometry of the nonplanar saddle-shaped mitral annulus can provide valuable information regarding the pathophysiology of mitral regurgitation (MR).

AIM OF THE WORK

To investigate mitral annular geometric deformities using three-dimensional echocardiography among patients with ischemic coronary illness with and without mitral regurgitation.

METHODS

Three-dimensional transesophageal echocardiographic data were acquired intraoperatively from patients with ischemic heart disease with or without associated mitral regurgitation who experienced coronary artery bypass grafting and normal control subjects. The mitral annulus was analyzed for differences in geometry using QLAB software.

RESULTS

Left ventricular ejection fraction was reduced in patients with ischemic heart disease and MR (n = 21; Group 1) and without MR (n = 7; Group 2) compared with that in normal subjects (n = 14; Group 3) (43.4% ± 11.8% and 35.9% ± 13.6% vs. 52.6% ± 9.3%, respectively; p = 0.015). Mitral annular height and mitral annular saddle-shaped nonplanarity were significantly lower in Group 1 compared to Group 2 and Group 3 (6.00 ± 1.07 mm, 7.96 ± 0.93 mm and 8.31 ± 1.12 mm; p < 0.0001) and (0.19 ± 0.04, 0.26 ± 0.04 and 0.26 ± 0.03; p < 0.0001) respectively while mitral annular ellipsicity and Mitral valve tenting volume were significantly higher in the same group (1) (114.82% ± 22.47%, 100.21% ± 9.87% and 97.29% ± 14.37%; p = 0.0421) and (2.73 ± 1.11, 2.20 ± 1.39 and 0.87 ± 0.67) respectively. Vena contracta diameter was inversely correlated with the mitral annular height (r = -0.82; p < 0.0001) and saddle-shaped nonplanarity of the annulus (r = -0.68; p < 0.0001).

CONCLUSION

Among patients with ischemic heart disease, there are significant increases in mitral valve tenting volume and height, and those with mitral regurgitation exhibited a reduced mitral annular height, a shallower saddle shape annulus and losses of ellipsicity of the annulus.

Annular dynamics after mitral valve repair with different prosthetic rings: A real-time three-dimensional transesophageal echocardiography study

PURPOSE

We assessed the effects of different types of prosthetic rings on mitral annular dynamics using real-time three-dimensional echocardiography (RT3DE).

METHODS

RT3DE was performed in 44 patients, including patients undergoing mitral annuloplasty using the Cosgrove-Edwards flexible band (Group A, n = 10), the semi-rigid Sorin Memo 3D ring (Group B, n = 17), the semi-rigid Edwards Physio II ring (Group C, n = 7) and ten control subjects. Various annular diameters were measured throughout the cardiac cycle.

RESULTS

We observed flexible anterior annulus motion in all of the groups except Group C. A flexible posterior annulus was only observed in Group B and the Control group. The mitral annular area changed during the cardiac cycle by 8.4 ± 3.2, 6.3 ± 2.0, 3.2 ± 1.3, and 11.6 ± 5.0 % in Group A, Group B, Group C, and the Control group, respectively. The dynamic diastolic to systolic change in mitral annular diameters was lost in Group C, while it was maintained in Group A, and to a good degree in Group B. In comparison to the Control group, the mitral annulus shape was more ellipsoid in Group B and Group C, and more circular in Group A.

CONCLUSION

Although mitral regurgitation was well controlled by all of the types of rings that were utilized in the present study, we demonstrated that the annulus motion and annulus shape differed according to the type of prosthetic ring that was used, which might provide important information for the selection of an appropriate prosthetic ring.

Quantitative Assessment of Mitral Apparatus Geometry Using Dual-Source Computed Tomography in Mitral Regurgitation

To quantitatively assess the geometric changes in mitral valve apparatus in mitral regurgitation (MR) by dualsource computed tomography (DSCT) and to analyze its impact on MR.The study subjects consisted of 20 controls, 20 patients with mild MR, and 30 patients with moderate to severe MR, all of whom underwent DSCT. The geometric parameters of the mitral valve were measured by CT and compared among the 3 groups. The correlations between DSCT measurements and MR severity were also analyzed.As regurgitation worsened, our results showed progressive enlargements of the mitral annular area, anteroposterior diameter, and mitral valve tenting area at the central level. Moreover, a higher mitral valve sphericity index and longer distance between the heads of the papillary muscles reflected a more outward displacement of the papillary muscles. The mitral annular area and tenting area at the central level had strong correlations with regurgitation severity.DSCT is available to quantitatively assess mitral valve morphology and provide additional information regarding its geometry. The mitral annular area and tenting area at the central level were the strongest determinants of MR severity.

Dynamism of the mitral annulus: a spatial and temporal analysis

OBJECTIVE

In this study, the authors sought to investigate the extent and timing of changes in mitral annular area during the cardiac cycle. Particularly, the authors assessed whether these changes were limited to the posterior part of the annulus or were more global in nature.

DESIGN

Prospective, observational study

SETTING

Tertiary care university hospital

PARTICIPANTS

Twenty three patients undergoing non-valvular cardiac surgery and 3 patients undergoing vascular procedures.

INTERVENTIONS

Intraoperative 3-dimensional transesophageal echocardiographic data obtained from patients with normal mitral valves undergoing non-valvular cardiac surgery were analyzed geometrically. Annular areas and diameters were measured during various stages of the cardiac cycle. Intertrigonal distance also was measured using 3D data.

MEASUREMENTS AND MAIN RESULTS

Both anterior and posterior portions of the mitral annulus demonstrated dynamism throughout the cardiac cycle. The expansion phase ranged from mid-systole to early-diastole, whereas mid-diastole to early-systole was characterized by an annular contraction phase. Area changes were contributed equally by anterior and posterior parts of the annulus. Annular dimensions increased in accordance with mitral annular area (p<0.05). Echocardiographically-identified intertrigonal distance showed the least delta change.

CONCLUSIONS

Both the anterior and posterior parts of the annulus contribute to changes in mitral annular area, which undergoes discrete expansion and contraction phases that extend into both systole and diastole. Compared to other annular dimensions, the echocardiographically-identified intertrigonal distance does not change significantly during the cardiac cycle.

Three-dimensional echocardiography and structural heart interventions

This article looks at the role of three-dimensional echocardiography in the anatomical assessment of cardiac structures, how this complements standard methods of assessing structural cardiac lesions and the advantages of three-dimensional echocardiography in peri-procedural guidance in the cardiac catheterization laboratory.

In-vivo analysis of selectively flexible mitral annuloplasty rings using three-dimensional echocardiography

BACKGROUND

Selectively flexible rings, Colvin-Galloway (CG) Future and Carpentier-Edwards (CE) Physio II, are used for annuloplasty during mitral valve repair to facilitate dynamic annular motion while preventing annular dilation. In this study, we assessed the extent and nature of the flexibility of these rings in vivo, which has not been objectively demonstrated.

METHODS

Three-dimensional transesophageal echocardiography was used intraoperatively to acquire data regarding dynamic motion of mitral annuli and annuloplasty rings in 33 patients undergoing mitral repair (15 CG Future and 18 CE Physio II) and in 15 control patients. Data were analyzed to assess the dynamic changes in annular geometry after implantation of selectively flexible rings.

RESULTS

After annuloplasty, there was an immediate and significant decrease in annular displacement (p < 0.001) and annular displacement velocity (p < 0.01). Dynamic change in multiple variables including anteroposterior diameter (p < 0.001) and annular area (p < 0.001) was also significantly depressed. In comparison with normal mitral valves, partially flexible rings allowed limited dynamic motion: percentage changes in anteroposterior diameter (p < 0.001), anterolateral posteromedial diameter (p < 0.001), and total circumference (p < 0.001) were significantly lower. Compared with each other, the two rings resulted in similar changes in anterior annulus length (p = 0.93), posterior annular length (p = 0.82), and annular area (p = 0.31).

CONCLUSIONS

Mitral annular dynamics were uniformly depressed after implantation of these rings. Selective flexibility could not be demonstrated in vivo using echocardiographic data.

Ischemic mitral regurgitation: mechanisms, intraoperative echocardiographic evaluation, and surgical considerations

Ischemic mitral regurgitation (IMR) is a subcategory of functional rather than organic, mitral valve (MV) disease. Whether reversible or permanent, left ventricular remodeling creates IMR that is complex and multifactorial. A comprehensive TEE examination in patients with IMR may have important implications for perioperative clinical decision making. Several TEE measures predictive of MV repair failure have been identified. Current practice among most surgeons is to typically repair the MV in patients with IMR. MV replacement is usually reserved for situations in which the valve cannot be reasonably repaired, or repair is unlikely to be tolerated clinically.

Creation of nonischemic functional mitral regurgitation by annular dilatation and nonplanar modification in a chronic in vivo swine model

BACKGROUND

Mechanisms and treatments of nonischemic functional mitral regurgitation (NIMR) are not fully established, in part, because of a lack of proper large animal models. We developed a novel technique of NIMR creation in a swine model by making multiple small incisions in the mitral annulus.

METHODS AND RESULTS

Ex vivo experiments using isolated swine hearts (n=10) showed a 15% increase in annular area (6.8-7.8 cm(2)) after 16 incisions were made along the posterior mitral annulus of a pressurized left ventricle. In an in vivo swine model (n=7; 46.4 ± 2.2 kg), NIMR was created by making fourteen to twenty-six 2-mm incisions in the atrial aspect of the mitral annulus using a cardioport video-assisted imaging system in the beating heart. Animals were euthanized at 4 weeks (n=4) and 6 weeks (n=3). Three-dimensional (3D) echocardiography was obtained before and immediately after NIMR creation and at euthanasia; vena contracta area, mitral annular dimension, left ventricular volume, and inter-papillary muscle distance were measured. The mitral annular incisions resulted in mild to moderate mitral regurgitation and an increased vena contracta area. NIMR creation altered mitral valve geometry by decreasing mitral annular nonplanarity and increasing annular area, primarily in the anteroposterior dimension. NIMR creation did not significantly change left ventricular volume or inter-papillary muscle distance. Longer follow-up period did not significantly affect these outcomes.

CONCLUSIONS

NIMR can successfully be created in a beating heart swine model and results in dilatation and 3D changes in mitral annular geometry. This model can enhance the experimental validation of new valve repair devices and techniques.

Dynamic indices of mitral valve function using perioperative three-dimensional transesophageal echocardiography

OBJECTIVE

Perioperative transesophageal echocardiography is essential for decision-making for mitral valve surgery. While two-dimensional transesophageal echocardiography represents the standard of care, tracking of dynamic changes using three-dimensional imaging permits assessment of morphologic and functional characteristics of the mitral valve. The authors hypothesized that quantitative three-dimensional analysis would reveal distinct differences among diseased, repaired, and normal mitral valves.

DESIGN

Case-control observational clinical study.

SETTING

Tertiary care hospital.

PARTICIPANTS

Using novel mitral valve quantification software, the authors retrospectively analyzed 80 datasets of cardiac surgery patients who underwent intraoperative transesophageal echocardiographic imaging. Twenty patients with degenerative mitral regurgitation were evaluated before and after mitral valve repair. Twenty patients had functional mitral regurgitation, and 20 patients had no mitral valve disease.

MEASUREMENTS AND MAIN RESULTS

Primary outcome measures of dynamic mitral valve function were: 1) three-dimensional annulus area, 2) annular displacement distance, 3) annular displacement velocity, and 4) annular area fraction. Other mitral annular tracking indices, in addition to intraobserver reliability and interobserver agreement, also were reported. Annulus area was enlarged in degenerative and functional mitral regurgitation. Annular displacement distance was decreased in functional mitral regurgitation and repaired valves. Annular displacement velocity was decreased in functional mitral regurgitation. Annular area fraction was decreased in functional mitral regurgitation and repaired valves. Intraobserver reliability and interobserver agreement were high for all 4 analyzed indices.

CONCLUSIONS

Normal, functional regurgitant, degenerative, and repaired mitral valves have distinctly different dynamic signatures of anatomy and function as reliably determined by perioperative echocardiographic tracking.