Optimized guidance of percutaneous edge-to edge repair of the mitral valve using real-time 3-D transesophageal echocardiography

3D echocardiography in mitral valve prolapse

Mitral valve prolapse (MVP) is the leading cause of mitral valve surgery. Echocardiography is the principal imaging modality used to diagnose MVP, assess the mitral valve morphology and mitral annulus dynamics, and quantify mitral regurgitation. Three-dimensional (3D) echocardiographic (3DE) imaging represents a consistent innovation in cardiovascular ultrasound in the last decades, and it has been implemented in routine clinical practice for the evaluation of mitral valve diseases. The focus of this review is the role and the advantages of 3DE in the comprehensive evaluation of MVP, intraoperative and intraprocedural monitoring.

Complications of the Percutaneous Mitral Valve Edge-To-Edge Repair: Role of Transesophageal Echocardiography

The use of transcatheter edge-to-edge repair for the treatment of mitral regurgitation has markedly increased in the last few years. The rate of adverse events related to the procedure is low; however, some of the complications that may occur are potentially dangerous. Due to the growing popularity of the technique, which is no longer limited to high-volume centers, knowledge of the complications related to the procedure is fundamental. Transesophageal echocardiography has a key role in the guidance of the intervention while allowing for the avoidance of most of these adverse events, as well as enabling us to diagnose them early. In this article, we review the main complications that might present during a transcatheter mitral edge-to-edge repair procedure (tamponade, thromboembolic events, single leaflet device attachment, device embolization, vascular injury…) while highlighting key aspects of transesophageal echocardiographic monitoring in the prevention and prompt diagnosis of these complications.

Advances in Procedural Echocardiographic Imaging in Transcatheter Edge-to-Edge Repair for Mitral Regurgitation

Transcatheter edge-to-edge repair (TEER) therapy is recommended by the American College of Cardiology/American Heart Association (ACC/AHA) guidelines for selected patients with symptomatic severe or moderate-severe mitral regurgitation (MR). Echocardiography, in particular transesophageal echocardiography (TEE), plays a critical role in procedural planning and guidance for TEER. Recent innovations and advances in TEE techniques including three-dimensional (3D) imaging, unlimited x-plane imaging, live 3D multiplanar reconstruction, as well as transillumination imaging with color Doppler and transparency rendering have further enhanced procedural imaging for TEER, especially for complex diseases including commissural defects, clefts, and multi-segment pathologies. This review discusses the technology of these advanced procedural imaging techniques and provides a "step-by-step" guide on how to apply them during the TEER procedure with a focus on their added values in treatment of complex valve lesions.

Imaging the mitral valve: a primer for the interventional surgeon

Transcatheter mitral valve interventions (TMVI) have evolved over the past decade as alternatives to open surgical repair for the therapeutic management of patients with severe mitral regurgitation (MR). Concurrent with the development of these technologies, quality multi-modality cardiac imaging has become essential in patient selection and procedural guidance. The former involves assessments of the pathophysiologic mechanisms of regurgitation, valvular anatomy and morphology, as well as objective quantification of the severity of MR. Both transthoracic and transesophageal echocardiography (TEE) are crucial and serve as the gateway to diagnosis and management of mitral valvular disease. Along with multi-detector computed tomography (CT) and cardiac magnetic resonance imaging (CMR), echocardiography plays an important role for preprocedural planning and evaluation of the spatial relationships of the mitral valvular complex with the coronary sinus, circumflex coronary artery and left ventricular (LV) outflow tract. Procedures that target mitral leaflets (e.g., MitraClip, PASCAL) or annulus (e.g., Cardioband, Carillon), or provide chordal (e.g., NeoChord, Harpoon) or valvular replacement, tend to be guided by TEE and assisted by fluoroscopy. As newer devices become available and outcomes of TMVI improve, cardiac imaging will undoubtedly continue to play an essential role in the success of percutaneous mitral valve repair (MVr) and replacement. The interventional surgeon of the future must therefore have a thorough understanding of the various imaging modalities while synthesizing and integrating novel concepts (e.g., neo-LV outflow tract) as applicable to assessing valvular function and pathology.

Multimodality Imaging in Secondary Mitral Regurgitation

Secondary mitral regurgitation (sMR) is characterized by left ventricular (LV) dilatation or dysfunction, resulting in failure of mitral leaflet coaptation. sMR complicates up to 35% of ischaemic cardiomyopathies (1) and 57% of dilated cardiomyopathies (2). Due to the prevalence of coronary artery disease worldwide, ischaemic cardiomyopathy is the most frequently encountered cause of sMR in clinical practice. Although mortality from cardiovascular disease has gradually fallen in Western countries, severe sMR remains an independent predictor of mortality (3) and hospitalization for heart failure (4). The presence of even mild sMR following acute MI reduces long-term survival free of major adverse events (1). Such adverse outcomes worsen as the severity of sMR increases, due to a cycle in which LV remodeling begets sMR and vice versa. Current guidelines do not recommend invasive treatment of the sMR alone as a first-line approach, due to the paucity of evidence supporting improvement in clinical outcomes. Furthermore, a lack of international consensus on the thresholds that define severe sMR has resulted in confusion amongst clinicians determining whether intervention is warranted (5, 6). The recent Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation (COAPT) trial (7) assessing the effectiveness of transcatheter mitral valve repair is the first study to demonstrate mortality benefit from correction of sMR and has reignited interest in identifying patients who would benefit from mitral valve intervention. Multimodality imaging, including echocardiography and cardiovascular magnetic resonance (CMR), plays a key role in helping to diagnose, quantify, monitor, and risk stratify patients for surgical and transcatheter mitral valve interventions.

Intraoperative transesophageal echocardiography in cardiovascular surgery. Consensus document from the Spanish Society of Anesthesia and Critical Care (SEDAR) and the Spanish Society of Endovascular and Cardiovascular Surgery (SECCE)

Transesophageal echocardiography is a semi-invasive technique that allows an evaluation of cardiac morphology and function in real time and it is a quality standard in cardiovascular surgery. It has become a fundamental tool for both monitoring and diagnosis in the intraoperative period that allows decide the correct surgical planning and pharmacological management. The goal of this document is to answer the questions of when and how the perioperative TEE should be performed in cardiovascular surgery, what are their applications in the intraoperative, who should perform it and how the information should be transmitted. The authors made a systematic review of international guidelines, review articles and clinical trials to answer by consensus to these questions.

Percutaneous Mitral Valve Repair: Multi-Modality Cardiac Imaging for Patient Selection and Intra-Procedural Guidance

Percutaneous mitral valve repair is an important procedure for patients at high risk of surgical mitral valve repair. Multi-modality Cardiac Imaging plays a key role in these procedures. MitraClip is the first and most utilized percutaneous mitral repair device and experience is has grown to treat not only typical but atypical and complex lesions. Cardioband is an emerging percutaneous annuloplasty system with promising early results. This review will focus on the comprehensive multi-modality cardiac imaging for patient selection and intra-procedural guidance of the MitraClip and Cardioband systems.

Percutaneous Transcatheter Edge-to-Edge MitraClip Technique: A Practical "Step-by-Step" 3-Dimensional Transesophageal Echocardiography Guide

Recent innovations and advancements in 3-dimensional (3D) echocardiography allow for better understanding of anatomic relationships and improve communication with the interventional cardiologist for guidance of catheter-based interventions. The mitral valve lends itself best for imaging with transesophageal echocardiography (TEE). Consequently, the role of 3D TEE in guiding catheter-based mitral interventions has been evolving rapidly. Although several publications have reported on the advantages and role of 3D TEE in guiding one or more of the steps involved in percutaneous mitral valve repair using the MitraClip, none offer a comprehensive and practical user-friendly guide. This review article provides the reader with practical intraprocedural tips on use of 3D TEE to guide all relevant steps involved in the procedure including how to acquire the images needed and what to look for.

Interventional Echocardiography: Field of Advanced Imaging to Support Structural Heart Interventions

Multimodality imaging, particularly echocardiography, is paramount in planning and guiding structural heart disease interventions. Transesophageal echocardiography remains unique in its ability to provide real-time 2D and 3D imaging of valvular heart disease and anatomic cardiac defects, which directly impacts the strategy and outcome of these procedures. This review summarizes the role of transesophageal echocardiography in patients undergoing the most common structural heart disease interventions.

3D and 4D Ultrasound: Current Progress and Future Perspectives

PURPOSE OF REVIEW

Three-dimensional (3D) echocardiography (3DE) and 4-dimensional echocardiography (4DE), also known as real-time (RT) 3DE (RT3DE), are rapidly emerging technologies which have made significant impact in the clinical arena over the years. This review will discuss the recent applications of 3DE in diagnosing and treating different types of cardiovascular disease.

RECENT FINDINGS

Recent studies using 3DE expanded on prior findings and introduced additional applications to different cardiac conditions. Some studies have used 3D parameters to prognosticate long-term outcomes. Numerous innovative software designs including fully automated algorithms have been introduced to better evaluate valvular heart disease and cardiac function.

SUMMARY

With further evolution of 3DE technologies, this imaging modality will emerge as a powerful tool and likely become the imaging modality of choice in the diagnosis and management of various cardiac disorders.

Role of Echocardiography in Transcatheter Valvular Heart Disease Interventions

PURPOSE OF REVIEW

Transcatheter valvular interventions have increased in importance and utility for surgical valve repair and replacement. Cardiac imaging is the most crucial aspect of procedural planning and guidance. Echocardiography is a widely used, portable, and dynamic imaging modality used for many of these interventions. This review will summarize the role echocardiography in structural heart valvular interventions.

RECENT FINDINGS

Intraprocedural echocardiographic guidance has been a mainstay of structural heart interventions. Over the years, the use of 3-dimensional echocardiography has increased, and studies have shown utility in paravalvular leak prediction in the setting of transcatheter aortic valve replacement, procedural guidance in MitraClip repair, and in mitral and tricuspid valve therapies. Intraprocedural echocardiography is of paramount important for procedural success during all structural heart valvular interventions. Continued use of 2 and 3-dimensional echocardiography will be a major factor in driving the innovative field of structural heart interventions forward.

Transcathether Valve Replacement and Valve Repair

Transcatheter aortic valve replacement for treatment of aortic stenosis has now become an accepted alternative to surgical valve replacement for some patients. In addition, transcatheter mitral valve repair is also routinely used in high surgical risk patients with mitral regurgitation. Other transcatheter procedures are in rapid development. The current review attempts to summarize the procedures and echocardiographic imaging used for transcatheter valve replacement or valve repair.

Ultrasound guidance for beating heart mitral valve repair augmented by synthetic dynamic CT

Minimally invasive valvular intervention commonly requires intra-procedural navigation to provide spatial and temporal information of relevant cardiac structures and device components. Recently intra-procedural trans-esophageal echocardiography (TEE) has been exploited for this purpose due to its accessibility, low cost, ease of use, and real-time imaging capacity. However, the position and orientation of tissue targets relative to surgical tools can be challenging to perceive, particularly using 2D imaging planes. In this paper, we propose the use of CT images to provide a high-quality 3D context to enhance ultrasound images through image registration, providing an augmented guidance system with minimal impact on standard clinical workflow. We also describe an approach to generate synthetic 4D CT images through non-rigid registration of available ultrasound. This can be employed to avoid a requirement for higher radiation. Synthetic CT images were validated through direct comparison of synthetic and real multi-phase CT images. Validation of CT and ultrasound image registration was performed for both dynamic and synthetic CT image datasets. Our results demonstrated that the synthetically generated dynamic CT images provide similar anatomical representation for relevant cardiac anatomy relative to real dynamic CT images, and similar high registration accuracy that can be achieved for intra-procedural TEE to this versus real dynamic CT images.

Recent advances in echocardiography for valvular heart disease

Echocardiography is the imaging modality of choice for the assessment of patients with valvular heart disease. Echocardiographic advancements may have particular impact on the assessment and management of patients with valvular heart disease. This review will summarize the current literature on advancements, such as three-dimensional echocardiography, strain imaging, intracardiac echocardiography, and fusion imaging, in this patient population.

A mitral annulus tracking approach for navigation of off-pump beating heart mitral valve repair

PURPOSE

To develop and validate a real-time mitral valve annulus (MVA) tracking approach based on biplane transesophageal echocardiogram (TEE) data and magnetic tracking systems (MTS) to be used in minimally invasive off-pump beating heart mitral valve repair (MVR).

METHODS

The authors' guidance system consists of three major components: TEE, magnetic tracking system, and an image guidance software platform. TEE provides real-time intraoperative images to show the cardiac motion and intracardiac surgical tools. The magnetic tracking system tracks the TEE probe and the surgical tools. The software platform integrates the TEE image planes and the virtual model of the tools and the MVA model on the screen. The authors' MVA tracking approach, which aims to update the MVA model in near real-time, comprises of three steps: image based gating, predictive reinitialization, and registration based MVA tracking. The image based gating step uses a small patch centered at each MVA point in the TEE images to identify images at optimal cardiac phases for updating the position of the MVA. The predictive reinitialization step uses the position and orientation of the TEE probe provided by the magnetic tracking system to predict the position of the MVA points in the TEE images and uses them for the initialization of the registration component. The registration based MVA tracking step aims to locate the MVA points in the images selected by the image based gating component by performing image based registration.

RESULTS

The validation of the MVA tracking approach was performed in a phantom study and a retrospective study on porcine data. In the phantom study, controlled translations were applied to the phantom and the tracked MVA was compared to its "true" position estimated based on a magnetic sensor attached to the phantom. The MVA tracking accuracy was 1.29 ± 0.58 mm when the translation distance is about 1 cm, and increased to 2.85 ± 1.19 mm when the translation distance is about 3 cm. In the study on porcine data, the authors compared the tracked MVA to a manually segmented MVA. The overall accuracy is 2.37 ± 1.67 mm for single plane images and 2.35 ± 1.55 mm for biplane images. The interoperator variation in manual segmentation was 2.32 ± 1.24 mm for single plane images and 1.73 ± 1.18 mm for biplane images. The computational efficiency of the algorithm on a desktop computer with an Intel(®) Xeon(®) CPU @3.47 GHz and an NVIDIA GeForce 690 graphic card is such that the time required for registering four MVA points was about 60 ms.

CONCLUSIONS

The authors developed a rapid MVA tracking algorithm for use in the guidance of off-pump beating heart transapical mitral valve repair. This approach uses 2D biplane TEE images and was tested on a dynamic heart phantom and interventional porcine image data. Results regarding the accuracy and efficiency of the authors' MVA tracking algorithm are promising, and fulfill the requirements for surgical navigation.

Safety and feasibility of novel technology fusing echocardiography and fluoroscopy images during MitraClip interventions

AIMS

The EchoNavigator (EN) software (Philips Healthcare, Best, The Netherlands) enables real-time fusion of echocardiography and fluoroscopy by co-registration of the echocardiography probe on the x-ray image. We aimed to evaluate the feasibility and safety of this novel software during MitraClip procedures.

METHODS AND RESULTS

Twenty-one patients were treated with the support of EchoNavigator software (EN+ patients). The primary (safety) endpoint was the total radiation dose. Secondary endpoints were fluoroscopy and total procedure time. The measurements were compared to those of 21 patients treated immediately before the installation of EchoNavigator (EN- patients). More MitraClips (45 vs. 36) were implanted in the EN+ group, mirroring more complex interventions in this group. In EN+ patients, radiation dose (Gy/cm2) was similar compared to EN- patients (146.5±123.6 vs.146.8±134.1, p=0.9). Total procedure time (minutes) was similar in the EN+ group compared to EN- patients (136.2±50.2 vs. 125.7±51.2, p=0.5). The main benefit of the EchoNavigator is the automated real-time fusion of echocardiography and fluoroscopy, leading to easier catheter manipulation.

CONCLUSIONS

The use of EchoNavigator software was feasible and safe in all study patients. Further studies are necessary to confirm the benefits of using this software.

Incremental value of 3-D transesophageal echocardiographic imaging of the mitral valve

Transesophageal echocardiography provides excellent visualization of the posteriorly located mitral valve. Over the last decade, 3-dimensional transesophageal echocardiography (3D TEE) has emerged as an exciting imaging modality, particularly of the mitral valve. The current generation matrix array technology allows the operator to perform 2D and 3D imaging with a single transducer. 3D TEE affords the unique ability to view the mitral valve and its surrounding structures "en face" in real time (RT), and provide contextual anatomical guidance during surgical and transcatheter interventions. Additionally, offline quantification has made significant contributions to our mechanistic understanding of the normal and diseased mitral valve, and alterations induced by therapeutic intervention such as surgical repair. This review will address recent advances in the incremental role of 3D TEE in mitral valve imaging.

[Echocardiography during transcatheter interventions. New developments]

Interventional techniques for percutaneous treatment of structural heart disease have become an important option for patients ineligible for conventional operating procedures in cardiovascular medicine. Echocardiography plays an essential role not only for patient selection but also for guiding transcatheter interventions in order to safely accomplish the procedure. Echocardiographic 2D and 3D techniques next to conventional fluoroscopy have therefore become an integral part for monitoring interventional procedures in the catheter laboratory. This review aims to describe new developments for the application of echocardiography during transcatheter interventions in the context of the current literature and current recommendations.

The evolving role of cardiac imaging in percutaneous valvular intervention

Surgical therapies have represented the primary evidence-based intervention to alter the natural history of valvular heart disease (VHD), however, the increasing incidence of patients at high surgical risk due to age and related co-morbid conditions has given rise to the need for alternative strategies. Thus, percutaneous approaches to VHD therapy have emerged as an important therapeutic option. Cardiovascular imaging plays a critical role in patient screening for percutaneous valvular interventions, during the procedure itself, and as part of follow-up for the identification of implant success/failure and complications. The technical demands on imaging in this context are highly specific. Although imaging has a significant role in the broader evaluation of valvular heart disease mechanism and severity, the purpose of this paper is to summarise the particular goals of cardiovascular imaging in the work-up for, during, and in the follow-up of percutaneous valvular intervention.

Real-time three-dimensional transesophageal echocardiography to predict artificial chordae length for mitral valve repair

Background

Artificial chordae replacement is an effective technique for mitral valve repair, however, it is difficult to accurately determine the length of artificial chordae. This study aimed to assess the reliability and accuracy of real-time three-dimensional transesophageal echocardiography (TEE) to predict the length of artificial chordae preoperatively.

Methods

From December 2008 to December 2010, 48 patients with severe mitral regurgitation successfully underwent mitral valve repair using artificial chordae replacement. The patients were divided into a TEE pre-measurement group (n = 26) and a direct measurement group (n = 22), according to the method used to determine the length of artificial chordae. Cardiopulmonary bypass time, aortic cross-clamp time, and the recurrence rate of moderate or severe mitral regurgitation were compared between the two groups.

Results

There were no operative deaths in either group. The mean cardiopulmonary bypass time was 113.0 ± 18.7 min and 127.0 ± 28.9 min (p < 0.05), and the aortic cross-clamp time was 70.0 ± 16.6 min and 86.0 ± 20.7 min (p < 0.05) in the TEE pre-measurement group and direct measurement group, respectively. The difference between the pre-measured artificial chordal length and actual constructed artificial chordal length was not significant in the TEE pre-measurement group (p > 0.05). Although the difference in the incidence of moderate or severe mitral regurgitation between the two groups was not significant (p > 0.05), the incidence in the TEE pre-measurement group (3.8%) was lower than that in the direct measurement group (18.2%).

Conclusions

Real-time three-dimensional transesophageal echocardiography can accurately predict the length of artificial chordae required for mitral valve repair, and shortens cardiopulmonary bypass time and aortic cross-clamp time while improving the results of mitral valve repair.

Analysis of procedural effects of percutaneous edge-to-edge mitral valve repair by 2D and 3D echocardiography

BACKGROUND

Analysis of procedural effects in patients undergoing percutaneous mitral valve repair (PMVR) using the edge-to-edge technique is complex, and common methods to define mitral regurgitation severity based on 2-dimensional (2D) echocardiography are not validated for postprocedural double-orifice mitral valve. This study used 3D transesophageal echocardiography (TEE) to determine the functional and morphological effects of PMVR.

METHODS AND RESULTS

In 39 high-risk surgical patients with moderate to severe functional mitral valve regurgitation, 3D TEE with and without color Doppler as well as 2D transthoracic and TEE was performed before and after PMVR (MitraClip device). Mitral valve regurgitant volume by color Doppler 3D TEE was determined as the product of vena contracta areas defined by direct planimetry and velocity time integral using continuous-wave Doppler. Regurgitant volume was reduced from 84.1±38.3 mL preintervention to 35.6±25.6 mL postintervention. Patients in whom vena contracta area could be reduced >50% had a smaller preprocedural mitral annulus area compared with patients with ≤50% reduction (11.9±3.9 versus 16.1±8.5 cm(2), respectively; P=0.036) and tended to have a smaller mitral annulus circumference (13.0±2.0 versus 14.8±4.1 cm, respectively; P=0.112). At 6 months follow-up, left atrial and left ventricular end-diastolic volumes were significantly more reduced in patients in whom regurgitant vena contracta area was reduced by >50% compared with those with less reduction (-11.4±5.2 versus -4.8±7.7%; P=0.005, and -11.0±7.2 versus -4.5±9.3%; P=0.028). The maximum diastolic mitral valve area decreased from 6.0±2.0 to 2.9±0.9 cm(2) (P<0.0001).

CONCLUSIONS

Three dimensional TEE demonstrates significant reduction of regurgitant volume after PMVR. The unique visualization of the mitral valve by 3D TEE allows improved understanding of the morphological and functional changes induced by PMVR.

Fast GPU based adaptive filtering of 4D echocardiography

Time resolved three-dimensional (3D) echocardiography generates four-dimensional (3D+time) data sets that bring new possibilities in clinical practice. Image quality of four-dimensional (4D) echocardiography is however regarded as poorer compared to conventional echocardiography where time-resolved 2D imaging is used. Advanced image processing filtering methods can be used to achieve image improvements but to the cost of heavy data processing. The recent development of graphics processing unit (GPUs) enables highly parallel general purpose computations, that considerably reduces the computational time of advanced image filtering methods. In this study multidimensional adaptive filtering of 4D echocardiography was performed using GPUs. Filtering was done using multiple kernels implemented in OpenCL (open computing language) working on multiple subsets of the data. Our results show a substantial speed increase of up to 74 times, resulting in a total filtering time less than 30 s on a common desktop. This implies that advanced adaptive image processing can be accomplished in conjunction with a clinical examination. Since the presented GPU processor method scales linearly with the number of processing elements, we expect it to continue scaling with the expected future increases in number of processing elements. This should be contrasted with the increases in data set sizes in the near future following the further improvements in ultrasound probes and measuring devices. It is concluded that GPUs facilitate the use of demanding adaptive image filtering techniques that in turn enhance 4D echocardiographic data sets. The presented general methodology of implementing parallelism using GPUs is also applicable for other medical modalities that generate multidimensional data.

Comparison of intraoperative three-dimensional Doppler color flow mapping to assess mitral regurgitation

BACKGROUND

Three-dimensional (3D) transesophageal echocardiography (TEE) enables the determination of the vena contracta area (VCA), which is an approved parameter to quantify mitral regurgitation (MR). The aim of this study was to determine the VCA in the operative setting and to compare it to alternative 3D and standard 2D methods, with respect to different etiologies of MR.

METHODS

MR in 56 consecutive patients undergoing cardiac surgery was evaluated using 2D and 3D TEE. VCA, vena contracta (VC), and effective regurgitation orifice area (EROA) by 3D and 2D flow convergence methods were determined. The correlations among the methods and the determined areas were evaluated.

RESULTS

EROA determination using 3D flow convergence areas correlated strongly with VCA (r = 0.653), however the resulting areas were considerably smaller. VC measurements in the 3D data set correlated slightly less (r = 0.629). EROA, which was determined using 2D flow convergence areas, showed the strongest correlation among the 2D methods (r = 0.406). 2D VC measurements showed weak to no correlation with VCA. Although a correlation was detected when using the biplane method or the midesophageal long-axis view to measure VC, statistical significance was only reached in functional MR and MR due to simple prolapse.

CONCLUSIONS

Intraoperative 3D methods to determine MR were feasible and showed improved correlation with VCA compared to 2D measurements. The agreement of 2D methods with VCA declined from functional MR to MR due to prolapse. We recommend the utilization of 3D color Doppler for intraoperative evaluation of MR, especially in patients with complex mitral valve prolapses.

The mechanobiology of mitral valve function, degeneration, and repair

In degenerative valve disease, the highly organized mitral valve leaflet matrix stratification is progressively destroyed and replaced with proteoglycan rich, mechanically inadequate tissue. This is driven by the actions of originally quiescent valve interstitial cells that become active contractile and migratory myofibroblasts. While treatment for myxomatous mitral valve disease in humans ranges from repair to total replacement, therapies in dogs focus on treating the consequences of the resulting mitral regurgitation. The fundamental gap in our understanding is how the resident valve cells respond to altered mechanical signals to drive tissue remodeling. Despite the pathological similarities and high clinical occurrence, surprisingly little mechanistic insight has been gleaned from the dog. This review presents what is known about mitral valve mechanobiology from clinical, in vivo, and in vitro data. There are a number of experimental strategies already available to pursue this significant opportunity, but success requires the collaboration between veterinary clinicians, scientists, and engineers.