Mitral Valve Prolapse With Mid-Late Systolic Mitral Regurgitation

Automatic Segmentation and Evaluation of Mitral Regurgitation Using Doppler Echocardiographic Images

BACKGROUND

Mitral Regurgitation (MR) is a common heart valve disease. Severe MR can lead to pulmonary hypertension, cardiac arrhythmia, and even death. Therefore, early diagnosis and assessment of MR severity are crucial. In this study, we propose a deep learning-based method for segmenting MR regions, aiming to improve the efficiency of MR severity classification and diagnosis.

METHODS

We enhanced the Efficient Multi-Scale Attention (EMA) module to capture multi-scale features more effectively, thereby improving its segmentation performance on MR regions, which vary widely in size. A total of 367 color Doppler echocardiography images were acquired, with 293 images used for model training and 74 images for testing. To fully validate the capability of the improved EMA module, we use ResUNet as the backbone, partially integrating the enhanced EMA module into the decoder's upsampling process. The proposed model is then compared with classic models like Deeplabv3+ and PSPNet, as well as UNet, ResUNet, ResUNet with the original EMA module added, and UNet with the improved EMA module added.

RESULTS

The experimental results demonstrate that the model proposed in this study achieved the best performance for the segmentation of the MR region on the test dataset: Jaccard (84.37%), MPA (92.39%), Recall (90.91%), and Precision (91.9%). In addition, the classification of MR severity based on the segmentation mask generated by our proposed model also achieved acceptable performance: Accuracy (95.27%), Precision (88.52%), Recall (91.13%), and F1-score (90.30%).

CONCLUSION

The model proposed in this study achieved accurate segmentation of MR regions, and based on its segmentation mask, automatic and accurate assessment of MR severity can be realized, potentially assisting radiologists and cardiologists in making decisions about MR.

Echocardiographic Assessment of Mitral Valve Prolapse Prevalence before and after the Year 1999: A Systematic Review

Background: Over the last five decades, a fair number of echocardiographic studies have evaluated the prevalence of mitral valve prolapse (MVP) in various cohorts of individuals, including heterogeneous study populations. The present systematic review has been primarily designed to summarize the main findings of these studies and to estimate the overall MVP prevalence in the general community. Methods: All echocardiographic studies assessing the MVP prevalence in various cohorts of individuals, selected from PubMed and EMBASE databases, were included. There was no limitation of time period. The risk of bias was assessed by using the National Institutes of Health (NIH) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Results: The full texts of 21 studies with 1354 MVP individuals out of 63,723 participants were analyzed. The overall pooled prevalence of MVP was 4.9% (range of 0.6-21%). When dividing the studies in two groups according to the echocardiographic criteria used for MVP diagnosis (less specific old criteria or more specific new criteria, respectively), the estimated pooled prevalence of MVP was 7.8% (range of 2-21%) for the older studies (performed between 1976 and 1998) and 2.2% (range of 0.6-4.2%) for the more recent ones (conducted between 1999 and 2021). Potential selection bias, hospital- or referral-based series, and the use of less specific echocardiographic criteria for MVP diagnosis have been indicated as the main reasons for the higher MVP prevalence detected by the older studies. MVP was commonly associated with a narrow antero-posterior thoracic diameter, isolated ventricular premature beats and nonspecific ST-T-wave abnormalities on a resting electrocardiogram, mild-to-moderate mitral regurgitation (MR), the reduced probability of obstructive coronary artery disease, and a low frequency of serious complications, such as severe MR, infective endocarditis, heart failure, stroke, and atrial fibrillation. Conclusions: MVP has a low prevalence in the general population, regardless of age, gender, and ethnicity, and is associated with a good outcome.

Quantification of Mitral Valve Regurgitation in Cavalier King Charles Spaniels and Chihuahuas Using Radius of Proximal Isovelocity Surface Area

Mitral regurgitation (MR) resulting from myxomatous mitral valve disease (MMVD) is a prevalent condition in dogs, particularly smaller breeds like Cavalier King Charles Spaniels (CKCSs) and Chihuahuas (CHHs). An accurate assessment of MR severity is essential for effective treatment and disease monitoring, yet a standardized method has yet to be established. In this retrospective study, we evaluated 124 client-owned dogs diagnosed with MMVD, including 64 CKCSs and 60 CHHs. Dogs were categorized into three stages: asymptomatic (B1), remodeled (B2), and congestive heart failure (CHF, C). The MR severity was quantified using the proximal isovelocity surface area (PISA) method, specifically focusing on the PISA radius (PISA-r). The PISA-r measurements exhibited significant increases across disease stages and demonstrated strong correlations with echocardiographic parameters (ranging from 0.83 to 0.94), including the left atrial size and left ventricular internal diameter. The receiver operating characteristic (ROC) curve analysis revealed the high sensitivity and specificity of PISA-r in classifying disease stages, establishing optimal cut-off values. The method displayed excellent repeatability (interobserver variability: 0.95) and reproducibility (intraobserver variability: 0.97). In conclusion, the PISA method, specifically PISA-r, was reliable for assessing MR severity in dogs with MMVD. By simplifying the diagnosis and management of MR, this research can potentially improve the life and management of MMVD-affected dogs.

EasyPISA: Automatic Integrated PISA Measurements of Mitral Regurgitation From 2-D Color-Doppler Using Deep Learning

OBJECTIVE

The proximal isovelocity surface area (PISA) method is a well-established approach for mitral regurgitation (MR) quantification. However, it exhibits high inter-observer variability and inaccuracies in cases of non-hemispherical flow convergence and non-holosystolic MR. To address this, we present EasyPISA, a framework for automated integrated PISA measurements taken directly from 2-D color-Doppler sequences.

METHODS

We trained convolutional neural networks (UNet/Attention UNet) on 1171 images from 196 recordings (54 patients) to detect and segment flow convergence zones in 2-D color-Doppler images. Different preprocessing schemes and model architectures were compared. Flow convergence surface areas were estimated, accounting for non-hemispherical convergence, and regurgitant volume (RVol) was computed by integrating the flow rate over time. EasyPISA was retrospectively applied to 26 MR patient examinations, comparing results with reference PISA RVol measurements, severity grades, and cMRI RVol measurements for 13 patients.

RESULTS

The UNet trained on duplex images achieved the best results (precision: 0.63, recall: 0.95, dice: 0.58, flow rate error: 10.4 ml/s). Mitigation of false-positive segmentation on the atrial side of the mitral valve was achieved through integration with a mitral valve segmentation network. The intraclass correlation coefficient was 0.83 between EasyPISA and PISA, and 0.66 between EasyPISA and cMRI. Relative standard deviations were 46% and 53%, respectively. Receiver operator characteristics demonstrated a mean area under the curve between 0.90 and 0.97 for EasyPISA RVol estimates and reference severity grades.

CONCLUSION

EasyPISA demonstrates promising results for fully automated integrated PISA measurements in MR, offering potential benefits in workload reduction and mitigating inter-observer variability in MR assessment.

Left Ventricular Fibrosis by Cardiac Magnetic Resonance Tissue Characterization in Chronic Mitral Regurgitation Patients

Background: Left ventricular remodeling in chronic mitral regurgitation (MR) encompasses two types of myocardial fibrosis: replacement fibrosis, identified by late gadolinium enhancement (LGE), and diffuse interstitial fibrosis, assessed by pre- and postcontrast T1 mapping techniques. These may explain irreversible LV dysfunction after MR correction. We aimed to assess the presence of myocardial fibrosis in patients with moderate and severe MR with no criteria for surgery versus mild MR controls. Methods: We enrolled 137 patients with chronic primary MR and 130 controls; all underwent cardiac magnetic resonance, and were followed up in a median of 2.9 years to assess mortality and the need for mitral valve replacement. Results: Patients in the study group displayed significantly higher degrees of LGE (28.4% vs 7.69%, p < 0.05), higher native T1 values (1167 ± 58.5 versus 971 ± 51.4 (p < 0.05)), and higher extracellular volumes compared to controls (32.3% ± 3.5 versus 23.9 ± 2.2, (p < 0.05)). The composite outcome occurred in 28 patients in the study group (20.4%), and significantly higher with LGE+ (78.5%). Replacement fibrosis (HR = 1.83, 95% CI, p < 0.01) and interstitial fibrosis (HR = 1.61, 95% CI, p < 0.01) were independent predictors for the composite outcome. Conclusions: Patients with moderate and severe MR with no criteria for surgery still exhibit a significant degree of both replacement and interstitial fibrosis, with prognostic implications.

The Pixel Variation Score: An Echocardiographic Index to Assess Temporal Variation of Mitral Regurgitant Flow

BACKGROUND

In mitral regurgitation (MR), temporal variation of MR flow has been considered an important reason for inaccurate MR grading. Current echocardiographic methods for assessing temporal MR flow variation are complex, and their clinical relevance has not been investigated. In this study, we investigated whether assessing MR flow variation using a dimensionless index with echocardiography is feasible, clinically meaningful, and related to patient outcomes.

METHODS

Consecutive patients with mitral valve prolapse (MVP, n = 244) and functional MR (FMR, n = 396) underwent comprehensive echocardiography. Mitral regurgitation severity was assessed using an integrated approach advocated by current guidelines. The MR continuous-wave Doppler envelope was divided into 3 segments of equal duration. Each segment's pixel intensity was assessed to calculate the pixel variation score (PVS).

RESULTS

The PVS was lower in FMR patients than in MVP patients. Lower PVS was associated with worse MR, larger left atrial and left ventricular dimensions, lower ejection fraction, and higher pulmonary artery pressures. In MVP, PVS was significantly associated with postoperative left ventricular reverse remodeling and was able to reclassify most patients in whom single-frame measures overestimated MR severity. Finally, PVS had incremental prognostic value on top of clinical and echocardiographic predictors of outcome.

CONCLUSIONS

Temporal variation in MR flow can reliably be assessed with echocardiography through analysis of the continuous-wave Doppler signal. A high PVS value may alert the echocardiographer to defer from single-frame MR grading and also suggests that the MR is probably not severe.

Arrhythmic Mitral Valve Prolapse: A Comprehensive Review

Mitral valve prolapse (MVP) is a prevalent cardiac disorder that impacts approximately 2% to 3% of the overall population. While most patients experience a benign clinical course, there is evidence suggesting that a subgroup of MVP patients face an increased risk of sudden cardiac death (SCD). Although a conclusive causal link between MVP and SCD remains to be firmly established, various factors have been associated with arrhythmic mitral valve prolapse (AMVP). This study aims to provide a comprehensive review encompassing the historical background, epidemiology, pathology, clinical manifestations, electrocardiogram (ECG) findings, and treatment of AMVP patients. A key focus is on utilizing multimodal imaging techniques to accurately diagnose AMVP and to highlight the role of mitral annular disjunction (MAD) in AMVP.

Pitfalls of mitral regurgitation assessment in the presence of mitral valve prolapse

Adequate grading of mitral regurgitation (MR) in patients with mitral valve prolapse (MVP) in the presence of mid-late systolic jets can represent a major challenge. In this entity, jets are commonly overestimated by echocardiography. Correct quantification is crucial and highly relevant for the further management and prognosis of these oftentimes young patients. This case points out potential pitfalls and underlines the importance to systematically include qualitative, quantitative, and semi-quantitative parameters into the echocardiographic assessment.

Primary Mitral Regurgitation and Heart Failure: Current Advances in Diagnosis and Management

Primary mitral regurgitation is a frequent etiology of congestive heart failure and is best treated with intervention when patients are symptomatic or when additional risk factors exist. Surgical intervention improves outcomes in appropriately selected patients. However, for those at high surgical risk, transcatheter intervention provides less invasive repair and replacement options while providing comparable outcomes to surgery. The excess mortality and high prevalence of heart failure in untreated mitral regurgitation illuminate the need for further developments in mitral valve intervention ideally fulfilled by expanding these types of procedures and eligibility to these procedures beyond only those at high surgical risk.

Echocardiography vs. CMR in the Quantification of Chronic Mitral Regurgitation: A Happy Marriage or Stormy Divorce?

Quantification of chronic mitral regurgitation (MR) is essential to guide patients’ clinical management and define the need and appropriate timing for mitral valve surgery. Echocardiography represents the first-line imaging modality to assess MR and requires an integrative approach based on qualitative, semiquantitative, and quantitative parameters. Of note, quantitative parameters, such as the echocardiographic effective regurgitant orifice area, regurgitant volume (RegV), and regurgitant fraction (RegF), are considered the most reliable indicators of MR severity. In contrast, cardiac magnetic resonance (CMR) has demonstrated high accuracy and good reproducibility in quantifying MR, especially in cases with secondary MR; nonholosystolic, eccentric, and multiple jets; or noncircular regurgitant orifices, where quantification with echocardiography is an issue. No gold standard for MR quantification by noninvasive cardiac imaging has been defined so far. Only a moderate agreement has been shown between echocardiography, either with transthoracic or transesophageal approaches, and CMR in MR quantification, as supported by numerous comparative studies. A higher agreement is evidenced when echocardiographic 3D techniques are used. CMR is superior to echocardiography in the calculation of the RegV, RegF, and ventricular volumes and can provide myocardial tissue characterization. However, echocardiography remains fundamental in the pre-operative anatomical evaluation of the mitral valve and of the subvalvular apparatus. The aim of this review is to explore the accuracy of MR quantification provided by echocardiography and CMR in a head-to-head comparison between the two techniques, with insight into the technical aspects of each imaging modality.

Quantification of primary mitral regurgitation by echocardiography: A practical appraisal

The accurate quantification of primary mitral regurgitation (MR) and its consequences on cardiac remodeling is of paramount importance to determine the best timing for surgery in these patients. The recommended echocardiographic grading of primary MR severity relies on an integrated multiparametric approach. It is expected that the large number of echocardiographic parameters collected would offer the possibility to check the measured values regarding their congruence in order to conclude reliably on MR severity. However, the use of multiple parameters to grade MR can result in potential discrepancies between one or more of them. Importantly, many factors beyond MR severity impact the values obtained for these parameters including technical settings, anatomic and hemodynamic considerations, patient's characteristics and echocardiographer' skills. Hence, clinicians involved in valvular diseases should be well aware of the respective strengths and pitfalls of each of MR grading methods by echocardiography. Recent literature highlighted the need for a reappraisal of the severity of primary MR from a hemodynamic perspective. The estimation of MR regurgitation fraction by indirect quantitative methods, whenever possible, should be central when grading the severity of these patients. The assessment of the MR effective regurgitant orifice area by the proximal flow convergence method should be used in a semi-quantitative manner. Furthermore, it is crucial to acknowledge specific clinical situations in MR at risk of misevaluation when grading severity such as late-systolic MR, bi-leaflet prolapse with multiple jets or extensive leak, wall-constrained eccentric jet or in older patients with complex MR mechanism. Finally, it is debatable whether the 4-grades classification of MR severity would be still relevant nowadays, since the indication for mitral valve (MV) surgery is discussed in clinical practice for patients with 3+ and 4+ primary MR based on symptoms, specific markers of adverse outcome and MV repair probability. Primary MR grading should be seen as a continuum integrating both quantification of MR and its consequences, even for patients with presumed "moderate" MR.

The evolving role of cardiovascular magnetic resonance in the assessment of mitral valve prolapse

Mitral valve prolapse (MVP), characterized by a displacement > 2 mm above the mitral annulus of one or both bileaflets, with or without leaflet thickening, is a common valvular heart disease, with a prevalence of approximately 2% in western countries. Although this population has a generally good overall prognosis, MVP can be associated with mitral regurgitation (MR), left ventricular (LV) remodeling leading to heart failure, ventricular arrhythmia, and, the most devastating complication, sudden cardiac death, especially in myxomatous bileaflet prolapse (Barlow's disease). Among several prognostic factors reported in the literature, LV fibrosis and mitral annular disjunction may act as an arrhythmogenic substrate in this population. Cardiac magnetic resonance (CMR) has emerged as a reliable tool for assessing MVP, MR severity, LV remodeling, and fibrosis. Indeed, CMR is the gold standard imaging modality to assess ventricular volume, function, and wall motion abnormalities; it allows accurate calculation of the regurgitant volume and regurgitant fraction in MR using a combination of LV volumetric measurement and aortic flow quantification, independent of regurgitant jet morphology and valid in cases of multiple valvulopathies. Moreover, CMR is a unique imaging modality that can assess non-invasively focal and diffuse fibrosis using late gadolinium enhancement sequences and, more recently, T1 mapping. This review describes the use of CMR in patients with MVP and its role in identifying patients at high risk of ventricular arrhythmia.

Watchful surgery in asymptomatic mitral valve prolapse

The most common organic etiology of mitral regurgitation is degenerative and consists of mitral valve prolapse (MVP). Volume overload because of mitral regurgitation is the most common complication of MVP. Advocating surgery before the consequences of volume overload become irreparable restores life expectancy, but carries a risk of mortality in patients who are often asymptomatic. On the other hand, the post-surgical outcome of symptomatic patients is dismal and life expectancy is impaired. In the present article, we aim to bridge the gap between these two therapeutic approaches, unifying the concepts of watchful waiting and early surgery in a "watchful surgery approach".

Patient Selection for Mitral Transcatheter Edge-to-Edge Repair

Mitral regurgitation (MR) is one of the most common valvular heart diseases, with many patients remaining non-suitable for surgical interventions. Transcatheter edge-to-edge repair (TEER) is a rapidly evolving procedure that allows safe and effective reduction of MR in high-risk patients. However, adequate patient selection through clinical assessment and imaging modalities remains a key factor for procedural success. In the following review, we highlight recent developments in TEER technologies that are expanding the target population and currently available imaging modalities that allow detailed evaluation of the mitral valve and surrounding structures for optimal patient selection.

The Role of Cardiovascular Magnetic Resonance in Patients with Mitral Regurgitation

The 2019 Global Burden of Disease (GBD) study estimated that there were approximately 24.2 million people affected worldwide by degenerative mitral regurgitation (MR), resulting in 34,200 deaths. After aortic stenosis, MR is the most prevalent VHD in Europe and the second-most common VHD to pose indications for surgery in western countries. Current ESC and AHA/ACC guidelines for the management of VHD emphasize the importance of an integrative approach for the assessment of MR severity, which is of paramount importance in dictating the timing for surgery. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) are the first-line imaging modalities; however, despite the technological advancement, sometimes, the final diagnosis on the degree of the disease may still be challenging. In the last 20 years, CMR has emerged as a robust technique in the assessment of patients with cardiac disease, and, recently, its role is gaining more and more importance in the field of VHD. In fact, CMR is the gold standard in the assessment of cardiac volumes, and it is possible to accurately evaluate the regurgitant volume. The purpose of this review is to outline the current state-of-the-art management of MR by using Cardiac Magnetic Resonance (CMR).

An Integrative, Multiparametric Approach to Mitral Regurgitation Evaluation

Echocardiography is the first-line modality for assessing mitral regurgitation (MR). In addition to evaluation of the MR jet characteristics, echocardiography can provide quantitative parameters of MR severity. This case series illustrates the importance of integrating multiple parameters in the evaluation of MR and the role of multimodality imaging. (Level of Difficulty: Advanced.)

Role of Cardiovascular Magnetic Resonance in Native Valvular Regurgitation: A Comprehensive Review of Protocols, Grading of Severity, and Prediction of Valve Surgery

Valvular regurgitation is common in developed countries with an increasing prevalence due to the aging of the population and more accurate diagnostic imaging methods. Echocardiography is the gold standard method for the assessment of the severity of valvular heart regurgitation. Nonetheless, cardiovascular magnetic resonance (CMR) has emerged as an additional tool for assessing mainly the severity of aortic and mitral valve regurgitation in the setting of indeterminate findings by echocardiography. Moreover, CMR is a valuable imaging modality to assess ventricular volume and flow, which are useful in the calculation of regurgitant volume and regurgitant fraction of mitral valve regurgitation, aortic valve regurgitation, tricuspid valve regurgitation, and pulmonary valve regurgitation. Notwithstanding this, reference values and optimal thresholds to determine the severity and prognosis of valvular heart regurgitation have been studied lesser by CMR than by echocardiography. Hence, further larger studies are warranted to validate the potential prognostic relevance of the severity of valvular heart regurgitation determined by CMR. The present review describes, analyzes, and discusses the use of CMR to determine the severity of valvular heart regurgitation in clinical practice.

Mitral Valve Prolapse-The Role of Cardiac Imaging Modalities

Mitral valve prolapse (MVP) is the most common nonischemic mitral regurgitation etiology and mitral abnormality requiring surgery in the Western world. There is an increasing awareness that pathological findings in MVP are not confined to the valve tissue; rather, it is a complex disease, involving the mitral valve apparatus, cardiac hemodynamics, and cardiac structure. Imaging has played a fundamental role in the understanding of the diagnosis, prevalence, and consequences of MVP. The diagnosis of MVP by imaging is based upon demonstrating valve leaflets ascending into the left atrium through the saddle-shaped annulus. Transthoracic and transesophageal echocardiography are the primary modalities in the diagnosis and assessment of MVP patients and must include careful assessment of the leaflets, annulus, chords, and papillary muscles. High-spatial-resolution imaging modalities such as cardiac magnetic resonance images and cardiac computed tomography play a secondary role in this regard and can demonstrate the anatomical relation between the mitral valve annulus and leaflet excursion for appropriate diagnosis. Ongoing development of new methods of cardiac imaging can help us to accurately understand the mechanism, diagnose the disease, develop an appropriate treatment plan, and estimate the risk for sudden death. Recently, several new observations with respect to prolapse have been derived from cardiac imaging including three-dimensional echocardiography and tissue-Doppler imaging. The aim of this article is to present these new imaging-derived insights for the diagnosis, risk assessment, treatment, and follow-up of patients with MVP.

Left Ventricular Remodeling in Non-syndromic Mitral Valve Prolapse: Volume Overload or Concomitant Cardiomyopathy?

Mitral valve prolapse (MVP) is a common valvular disorder that can be associated with mitral regurgitation (MR), heart failure, ventricular arrhythmias and sudden cardiac death. Given the prognostic impact of these conditions, it is important to evaluate not only mitral valve morphology and regurgitation, but also the presence of left ventricular (LV) function and remodeling. To date, several possible hypotheses have been proposed regarding the underlying mechanisms of LV remodeling in the context of non-syndromic MVP, but the exact pathophysiological explanation remains elusive. Overall, volume overload related to severe MR is considered the main cause of LV dilatation in MVP. However, significant LV remodeling has been observed in patients with MVP and no/mild MR, particularly in patients with bileaflet MVP or Barlow's disease, generating several new hypotheses. Recently, the concept of "prolapse volume" was introduced, adding a significant volume load to the LV on top of the transvalvular MR volume. Another possible hypothesis is the existence of a concomitant cardiomyopathy, supported by the link between MVP and myocardial fibrosis. The origin of this cardiomyopathy could be either genetic, a second hit (e.g., on top of genetic predisposition) and/or frequent ventricular ectopic beats. This review provides an overview of the different mechanisms and remaining questions regarding LV remodeling in non-syndromic MVP. Since technical specifications of imaging modalities impact the evaluation of MR severity and LV remodeling, and therefore might influence clinical decision making in these patients, this review will also discuss assessment of MVP using different imaging modalities.

Echocardiographic Advances in Dilated Cardiomyopathy

Although the overall survival of patients with dilated cardiomyopathy (DCM) has improved significantly in the last decades, a non-negligible proportion of DCM patients still shows an unfavorable prognosis. DCM patients not only need imaging techniques that are effective in diagnosis, but also suitable for long-term follow-up with frequent re-evaluations. The exponential growth of echocardiography’s technology and performance in recent years has resulted in improved diagnostic accuracy, stratification, management and follow-up of patients with DCM. This review summarizes some new developments in echocardiography and their promising applications in DCM. Although nowadays cardiac magnetic resonance (CMR) remains the gold standard technique in DCM, the echocardiographic advances and novelties proposed in the manuscript, if properly integrated into clinical practice, could bring echocardiography closer to CMR in terms of accuracy and may certify ultrasound as the technique of choice in the follow-up of DCM patients. The application in DCM patients of novel echocardiographic techniques represents an interesting emergent research area for scholars in the near future.

Valvular regurgitation flow jet assessment using in vitro 4D flow MRI: Implication for mitral regurgitation

PURPOSE

The purpose of this study was to evaluate the accuracy of four-dimensional (4D) flow MRI for direct assessment of peak velocity, flow volume, and momentum of a mitral regurgitation (MR) flow jets using an in vitro pulsatile jet flow phantom. We systematically investigated the impact of spatial resolution and quantification location along the jet on flow quantities with Doppler ultrasound as a reference for peak velocity.

METHODS

Four-dimensional flow MRI data of a pulsatile jet through a circular, elliptical, and 3D-printed patient-specific MR orifice model was acquired with varying spatial resolution (1.5-5 mm isotropic voxel). Flow rate and momentum of the jet were quantified at various axial distances (x = 0-50 mm) and integrated over time to calculate Vol_jet and MTI_jet . In vivo assessment of Vol_jet and MTI_jet was performed on 3 MR patients.

RESULTS

Peak velocities were comparable to Doppler ultrasound (3% error, 1.5 mm voxel), but underestimated with decreasing spatial resolution (-40% error, 5 mm voxel). Vol_jet was similar to regurgitant volume (RVol) within 5 mm, and then increased linearly with the axial distance (19%/cm) because of flow entrainment. MTI_jet remained steady throughout the jet (2%/cm) as theoretically predicted. Four and 9 voxels across the jet were required to measure flow volume and momentum-time-integral within 10% error, respectively.

CONCLUSION

Four-dimensional flow MRI detected accurate peak velocity, flow rate, and momentum for in vitro MR-mimicking flow jets. Spatial resolution significantly impacted flow quantitation, which otherwise followed predictions of flow entrainment and momentum conservation. This study provides important preliminary information for accurate in vivo MR assessment using 4D flow MRI.

Computational Analysis of Virtual Echocardiographic Assessment of Functional Mitral Regurgitation for Validation of Proximal Isovelocity Surface Area Methods

BACKGROUND

Mitral regurgitation (MR) quantification by the proximal isovelocity surface area (PISA) method remains challenging. Using computer models, the authors evaluated the accuracy of different PISA methods and quantified their errors.

METHODS

Five functional MR computer models of different geometric and tethering abnormalities were created, validated, and treated as phantom models, from which the reference values were directly obtained. Virtual two-dimensional (2D) PISA and three-dimensional (3D) PISA (both peak and integrated values) were performed on these phantom models. By comparing virtual PISA results with reference values, the accuracy of different PISA methods was evaluated, and their sources of errors were quantified.

RESULTS

Compared with reference values of regurgitant flow rate, excellent correlations were found for true PISA (r = 0.99, bias = 32.3 ± 35.3 mL/sec), 3D PISA (r = 0.97, bias = -24.4 ± 55.5 mL/sec), followed by multiplane 2D hemicylindrical PISA (r = 0.88, bias = -24.1 ± 85.4 mL/sec) and hemiellipsoidal PISA (r = 0.91, bias = -55.7 ± 96.6 mL/sec). Weaker correlations were found for single-plane 2D hemispherical PISA (parasternal long-axis: r = 0.71, bias = -77.6 ± 124.5 mL/sec; apical two-chamber: r = 0.69, bias = -52.0 ± 122.0 mL/sec; apical four-chamber: r = 0.82, bias = -65.5 ± 107.3 mL/sec). For regurgitant volume quantification, integrated PISA was more accurate than peak PISA. The bias of 3D PISA improved from -12.7 ± 7.8 mL (peak PISA) to -2.1 ± 5.3 mL (integrated PISA).

CONCLUSIONS

For functional MR quantification, 2D hemispherical PISA had significant underestimation, multiplane 2D hemiellipsoidal and hemicylindrical PISA showed improved accuracy, and 3D PISA was the most accurate. The PISA method is subject to both systematic underestimation due to the Doppler angle effect and systematic overestimation when regurgitant flow is not perpendicular to PISA contour. Integrated PISA is able to capture dynamic MR and is therefore more accurate than peak PISA. The sum of regurgitant flow rates is the most feasible way to perform integrated PISA.

Diagnostic and Prognostic Value of Several Color Doppler Jet Grading Methods in Patients With Mitral Regurgitation

Color Doppler is a widely used ultrasound imaging method for assessing mitral regurgitation (MR) in clinical practice. Nevertheless, color Doppler-based grading of the MR jet has been rarely considered in clinical studies. We investigated the diagnostic and prognostic value of several color Doppler MR jet grading methods and compared them with quantitative grading of MR. The MR color Doppler jet was assessed in 476 MR patients using an 'integrated' eyeballing approach by quantifying the color Doppler jet area, jet area/left atrium area and jet length and using quantitative methods. Clinical endpoints were scored as major adverse clinical events, including cardiovascular death, heart failure hospitalization and mitral valve intervention. When assessed by three echocardiographers, there was a moderate inter-observer agreement for eyeballing color Doppler grade of MR (intraclass correlation coefficient 0.69, p < 0.001). The intra-observer agreement was good for all color Doppler approaches. In primary MR, eyeballing color Doppler correlated well with (in)direct measures of MR severity, with a negative predictive value of 91% when using a grade 2 color Doppler as cut-off. In secondary MR, eyeballing color Doppler grade and jet length were predictors of clinical outcome in Cox proportional hazards analysis (p = 0.003), independent of pulmonary pressures, atrial and ventricular volumes. Overall, the integrated eyeballing approach performed better than color Doppler quantification of the MR jet area and length. In conclusion, this study shows that color Doppler grading of the distal MR jet performs well in predicting events in primary and secondary MR, compared to quantitative grading methods.

Quantification of regurgitation in mitral valve prolapse with automated real time echocardiographic 3D proximal isovelocity surface area: multimodality consistency and role of eccentricity index

Three-dimensional transthoracic echocardiography (3D-TTE) provides a semi-automated proximal isovelocity surface area method (3D-PISA) to obtain quantitative parameters. Data assessing regurgitation severity in mitral valve prolapse (MVP) are scarce, so we assessed the 3D-PISA method compared with 2D-PISA and cardiovascular magnetic resonance (CMR) and the role of an eccentricity index. We evaluated the 3D-PISA method for assessing MR in 54 patients with MVP (57 ± 14 years; 42 men; 12 mild/mild-moderate; 12 moderate-severe; and 30 severe MR). Role of an asymmetric (i.e. eccentricity index ≥ 1.25) flow convergence region (FCR) and inter-modality consistency were then assessed. 3D-PISA derived regurgitant volume (RVol) showed a good correlation with 2D-PISA and CMR derived parameters (r = 0.86 and r = 0.81, respectively). The small mean differences with 2D-PISA derived RVol did not reach statistical significance in overall population (5.7 ± 23 ml, 95% CI - 0.6 to 12; p = 0.08) but differed in those with asymmetric 3D-FCR (n = 21; 2D-PISA: 72 ± 36 ml vs. 3D-PISA: 93 ± 47 ml; p = 0.001). RVol mean values were higher using PISA methods (CMR 57 ± 33 ml; 2D-PISA 73 ± 39 ml; and 3D-PISA 79 ± 45 ml) and an overestimation was observed when CMR was used as reference (2D-PISA vs. CMR: mean difference: 15.8 ml [95% CI 10-22, p < 0.001]; and 3D-PISA vs. CMR: 21.5 ml [95% CI 14-29, p < 0.001]). Intra- and inter-observer reliability was excellent (ICC 0.91-0.99), but with numerically lower coefficient of variation for 3D-PISA (8%-10% vs. 2D-PISA: 12%-16%). 3D-PISA method for assessing regurgitation in MVP may enable analogous evaluation compared to standard 2D-PISA, but with overestimation in case of asymmetric FCR or when CMR is used as reference method.

Myxomatous Mitral Valve Disease with Mitral Valve Prolapse and Mitral Annular Disjunction: Clinical and Functional Significance of the Coincidence

The morphological changes that occur in myxomatous mitral valve disease (MMVD) involve various components, ultimately leading to the impairment of mitral valve (MV) function. In this context, intrinsic mitral annular abnormalities are increasingly recognized, such as a mitral annular disjunction (MAD), a specific anatomical abnormality whereby there is a distinct separation between the mitral annulus and the left atrial wall and the basal portion of the posterolateral left ventricular myocardium. In recent years, several studies have suggested that MAD contributes to myxomatous degeneration of the mitral leaflets, and there is growing evidence that MAD is associated with ventricular arrhythmias and sudden cardiac death. In this review, the morphological characteristics of MAD and imaging tools for diagnosis will be described, and the clinical and functional aspects of the coincidence of MAD and myxomatous MVP will be discussed.

Basic Principles of the Echocardiographic Evaluation of Mitral Regurgitation

Mitral regurgitation (MR) is a common form of valvular heart disease that is associated with significant morbidity and mortality. Treatment decisions are completely dependent on accurate diagnosis of both mechanism and severity of MR, which can be challenging and is often done incorrectly. Transthoracic echocardiography is the most commonly used imaging test for MR; transesophageal echocardiography is often needed to better define morphology and MR severity, and is essential for guiding transcatheter therapies for MR. Multidetector computed tomography has become the standard to assess whether transcatheter valve replacement is an option because of its ability to assess valve sizing, access, and potential left ventricular outflow tract obstruction. Finally, cine cardiac magnetic resonance has been recommended by recent guidelines to quantify MR severity when the distinction between moderate and severe MR is indeterminate by echocardiography. This paper focuses on the main questions to be answered by imaging techniques and illustrates some common tips, tricks, and pitfalls in the assessment of MR.

Three-dimensional transthoracic echocardiographic evaluation of tricuspid regurgitation severity using proximal isovelocity surface area: comparison with volumetric method

BACKGROUND

The quantification of tricuspid regurgitation(TR) using three-dimensional(3D) proximal isovelocity surface area (PISA) derived effective regurgitant orifice area (EROA) is feasible in functional TR. The aim of our study was to explore the diagnostic accuracy and utility of 3D PISA EROA in a larger population of different etiologies.

METHODS

One hundred and seven patients with confirmed TR underwent 2D and 3D transthoracic echocardiography (TTE). 3D PISA EROA was calculated and EROA derived from 3D regurgitant volume (Rvol) was used as the reference.

RESULTS

3D PISA EROA showed better correlation in primary TR than in functional TR(r = 0.897, P < 0.01). 3D PISA EROA differentiated severe TR with comparable accuracy in patients with primary and functional etiology (Z-value 16.506 vs 21.202), but with different cut-offs (0.49cm² vs. 0.41 cm²). The chi-square value for incorporated clinical symptoms, positive echocardiographic results and 3D PISA EROA to grade severe TR was higher than only included clinical symptoms or incorporated clinical symptoms and positive echocardiographic results (chi-square value 137.233, P < 0.01).

CONCLUSION

TR quantification using 3D PISA EROA is feasible and accurate under different etiologies. It has incremental diagnostic value for evaluating severe TR.

Relations of Augmented Systolic Annular Expansion and Leaflet/Papillary Muscle Dynamics in Late-Systolic Mitral Valve Prolapse Evaluated by Echocardiography with a Speckle Tracking Analysis

The mechanism of systolic annular expansion in mitral valve prolapse (MVP) is not clarified. Since annular expansion is systolic outward shift of MV leaflet/chorda tissue complex at superior and outer ends, annular expansion could be related to inward (superior) shift of the complex at another inferior and inner end of the papillary muscle (PM) tip and/or systolic lengthening of the tissue complex, especially MV leaflets.MV annulus systolic expansion, PMs' systolic superior shift, and MV leaflets' systolic lengthening were evaluated by echocardiography with a speckle tracking analysis in 25 normal subjects, 25 subjects with holo-systolic MVP and 20 subjects with late-systolic MVP.PMs' superior shift, MV leaflets' lengthening, MV annular area at the onset of systole and subsequent MV annulus expansion were significantly greater in late-systolic MVP than in holo-systolic MVP (4.6 ± 1.6 versus 1.5 ± 0.7 mm/m², 2.5 ± 1.4 versus 0.6 ± 2.0 mm/m², 6.8 ± 2.5 versus 5.7 ± 1.0 cm²/m² and 1.6 ± 0.8 versus 0.1 ± 0.5 cm²/m², P < 0.001, respectively). Multivariate analysis identified MV leaflets' lengthening and PMs' superior shift as independent factors associated with MV annular expansion.Conclusions: These results suggest that systolic MV annular expansion in MVP is related to abnormal MV leaflets' lengthening and PMs' superior shift.

Reproducibility of reading echocardiographic parameters to assess severity of mitral regurgitation. Insights from a French multicentre study

BACKGROUND

Poor reproducibility in assessment of mitral regurgitation (MR) has been reported.

AIM

To investigate the robustness of echocardiographic MR assessment in 2019, based on improvements in technology and the skill of echocardiographists regarding MR quantification.

METHODS

Reproducibility in parameters of MR severity and global rating were tested using transthoracic echocardiography in 25 consecutive patients independently analysed by 16 junior and senior cardiologists specialized in echocardiography (400 analyses per parameter).

RESULTS

Overall interobserver agreement for mechanism definition, effective regurgitant orifice area (EROA) and regurgitant volume (RVol) was moderate, and was lower in secondary MR. Interobserver agreement was substantial for EROA [0.61, 95% confidence interval (CI) 0.45-0.75] and moderate for RVol with the PISA method (0.50, 95% CI 0.33-0.56) in senior physicians and was fair in junior physicians (0.33, 95% CI 0.19-0.51 and 0.36, 95% CI 0.36-0.43, respectively). Using a multiparametric approach, overall interobserver agreement for grading MR severity was fair (0.30), was slightly better in senior than in junior physicians (0.31 vs. 0.28, respectively) with substantial or almost perfect agreement more frequently observed in senior versus junior physicians (52% vs. 36%, respectively).

CONCLUSION

Reproducible transthoracic echocardiography MR quantification remains challenging in 2019, despite the expected high skills of echocardiographers regarding MR at the time of dedicated percutaneous intervention. The multiparametric approach does not entirely alleviate the substantial dispersion in measurement of MR severity parameters, whereas reader experience seems to partially address the issue. Our study emphasizes the continuing need for multimodality imaging and education in the evaluation of MR among cardiologists.

Degenerative mitral regurgitation

PURPOSE OF REVIEW

Degenerative mitral regurgitation (DMR) continues to be an important cause of morbidity and mortality with surgical mitral valve repair remaining the gold standard for the treatment of severe disease. The purpose of this review is to summarize recent advances in the understanding of DMR as well as the progress made in its assessment with a focus on imaging techniques.

RECENT FINDINGS

Recent insights into the anatomy and physiology of DMR challenge the assumption that fibroelastic deficiency and Barlow disease are part of a single DMR spectrum. Advances in echocardiography and cardiovascular MRI have the potential to improve quantification of mitral regurgitation, provide unique information on prognosis and impact of DMR, further the association between DMR and arrhythmic risk and aide in decision-making for DMR treatment.

SUMMARY

With growing interest in the use of noninvasive transcatheter therapies in the mitral valve space, comprehensive assessment of the mitral valve is critical to instruct decision-making and guide therapeutic strategy.

The Average Pixel Intensity Method and Outcome of Mitral Regurgitation in Mitral Valve Prolapse

BACKGROUND

Mitral regurgitation (MR) is a frequent consequence of mitral valve prolapse (MVP). However, the echocardiographic grading of MR is challenging, and the recommended grading parameters have several limitations. The authors developed a novel echocardiographic parameter to grade MR, the average pixel intensity (API) method, on the basis of pixel intensity analysis of the continuous-wave Doppler signal.

METHODS

Transthoracic echocardiography was performed prospectively in consecutive patients with MVP (N = 149). MR was quantitatively assessed using the API method, vena contracta width, effective regurgitant orifice area, and regurgitant volume. The primary clinical events were cardiovascular mortality, mitral valve surgery, percutaneous mitral intervention, and heart failure hospitalization.

RESULTS

The API method was feasible in 90% of all patients with MVP, which was significantly higher than vena contracta width, effective regurgitant orifice area, and regurgitant volume. During a median follow-up period of 17 months, 44 patients (32%) had major adverse cardiac events, and the majority of events occurred in the holosystolic MVP subgroup. The degree of MR severity by the API method was highly significant for the prediction of events. An API cutoff of 111 arbitrary units was defined as "severe" MR due to MVP, with overall superior sensitivity and specificity compared with cutoffs for established MR grading parameters. In patients who did not have major adverse cardiac events during the follow-up period (n = 92), no significant changes in measures of MR severity were found on follow-up echocardiography.

CONCLUSIONS

The API method is predictive of clinical events and outcomes in MR due to MVP. Therefore, the API method may be considered for grading the severity of MR due to MVP in clinical practice.

Possible mechanism of late systolic mitral valve prolapse: systolic superior shift of leaflets secondary to annular dilatation that causes papillary muscle traction

Progressive superior shift of the mitral valve (MV) during systole is associated with abnormal papillary muscle (PM) superior shift in late systolic MV prolapse (MVP). The causal relation of these superior shifts remains unclarified. We hypothesized that the MV superior shift is related to augmented MV superiorly pushing force by systolic left ventricular pressure due to MV annular dilatation, which can be corrected by surgical MV plasty, leading to postoperative disappearance of these superior shifts. In 35 controls, 28 patients with holosystolic MVP, and 28 patients with late systolic MVP, the MV coaptation depth from the MV annulus was measured at early and late systole by two-dimensional echocardiography. The PM tip superior shift was monitored by echocardiographic speckle tracking. MV superiorly pushing force was obtained as MV annular area × (systolic blood pressure - 10). Measurements were repeated after MV plasty in 14 patients with late systolic MVP. Compared with controls and patients with holosystolic MVP, MV and PM superior shifts and MV superiorly pushing force were greater in patients with late systolic MVP [1.3 (0.5) vs. 0.9 (0.6) vs. 3.9 (1.0) mm/m², 1.3 (0.5) vs. 1.2 (1.0) vs. 3.3 (1.3) mm/m², and 487 (90) vs. 606 (167) vs. 742 (177) mmHg·cm²·m^-2, respectively, means (SD), P < 0.001]. MV superior shift was correlated with PM superior shift ( P < 0.001), which was further related to augmented MV superiorly pushing force ( P < 0.001). MV and PM superior shift disappeared after surgical MV plasty for late systolic MVP. These data suggest that MV annulus dilatation augmenting MV superiorly pushing force may promote secondary superior shift of the MV (equal to late systolic MVP) that causes subvalvular PM traction in patients with late systolic MVP. NEW & NOTEWORTHY Late systolic mitral valve prolapse (MVP) is associated with mitral valve (MV) and papillary muscle (PM) abnormal superior shifts during systole, but the causal relation remains unclarified. MV and PM superior shifts were correlated with augmented MV superiorly pushing force by annular dilatation and disappeared after surgical MV plasty with annulus size and MV superiorly pushing force reduction. This suggests that MV annulus dilatation may promote secondary superior shifts of the MV (late systolic MVP) that cause subvalvular PM traction.

Role of Cardiac Magnetic Resonance Imaging in Valvular Heart Disease: Diagnosis, Assessment, and Management

PURPOSE OF REVIEW

This article will review the current techniques in cardiac magnetic resonance imaging (CMR) for diagnosing and assessing primary valvular heart disease.

RECENT FINDINGS

The recent advancements in CMR have led to an increased role of this modality for qualifying and quantifying various native valve diseases. Phase-contrast velocity encoded imaging is a well-established technique that can be used to quantify aortic and pulmonic flow. This technique, combined with the improved ability for CMR to obtain accurate left and right ventricular volumetrics, has allowed for increased accuracy and reproducibility in assessing valvular dysfunction. Advancements in CMR technology also allows for improved spatial and temporal resolution imaging of various valves and their regurgitant or stenotic jets. Therefore, CMR can be a powerful tool in evaluation of native valvular heart disease. The role of CMR in assessing valvular heart disease is growing and being recognized in recent guidelines. CMR has the ability to assess valve morphology along with qualifying and quantifying valvular disease. In addition, the ability to obtain accurate volumetric measurements may improve more precise management strategies and may lead to improvements in mortality and morbidity.

Identification and Quantification of Degenerative and Functional Mitral Regurgitation for Patient Selection for Transcatheter Mitral Valve Repair

Chronic mitral regurgitation (MR), whether due to valve degeneration or secondary to myocardial disease, affects an increasing proportion of the aging population. Percutaneous mitral valve interventions, including edge-to-edge repair, are emerging as feasible and effective therapy for patients with severe MR at high or prohibitive surgical risk. Imaging with echocardiography is crucial for patient selection by evaluating mitral anatomy, the mechanism of dysfunction, and MR severity. In this article, the authors review the imaging characteristics for identifying and quantifying degenerative and functional MR for transcatheter mitral valve repair.