Assessment of mitral valve morphology using three-dimensional echocardiography. Feasibility and reference values

Current use of real-time three-dimensional transthoracic echocardiography in animals

This review includes 36 studies of transthoracic real-time three-dimensional echocardiography (RT3DE) in animals. Most of these studies concern cardiac chamber quantification of the left atrium and left ventricle, in dogs. Comparisons of RT3DE and different two-dimensional echocardiographic (2DE) methods have been reported in dogs with myxomatous mitral valve disease (MMVD), dilated cardiomyopathy, and in healthy control dogs. Comparisons of RT3DE and standard reference methods have been reported in healthy control dogs. In dogs with MMVD, volumetric RT3DE measurements of left atrium do not appear to provide superior prognostic value compared with 2DE methods using Simpson's method of discs in dogs with MMVD. The major advantages of RT3DE compared to 2DE include improvements in visualization of the complex morphology of the mitral valve, the estimation of mitral valve regurgitation, and improved visualization of complex congenital cardiac abnormalities.

Echocardiographic evaluation of deformity and enlargement of the canine mitral valve annulus associated with myxomatous degenerative mitral valve disease

INTRODUCTION/OBJECTIVES

Quantitative evaluation of the morphology of the mitral valve annulus (MVA) in dogs with myxomatous mitral valve disease (MMVD) may improve the techniques of mitral valve plasty. This study aimed to compare the MVA morphology on echocardiography in normal dogs and dogs with MMVD and to compare the echocardiographic and intraoperative measurements of the MVA in dogs with MMVD.

ANIMALS, MATERIALS AND METHODS

The study population comprised 59 healthy dogs (control group) and 371 dogs with MMVD (MMVD group). The anterior-posterior diameter and transversal diameter (TD) of the MVA and the aortic annulus diameter were measured by echocardiography to calculate the mitral valve flattening ratio, mitral annulus area (MAA), mitral annulus circumference (MAC), contraction ratio of the MAA and aortic annulus area. In the MMVD group, the mitral annulus diameter (MAD) was macroscopically measured during mitral valve plasty. Areas and lengths were divided by the body surface area (BSA) and √BSA, respectively, for comparative analyses.

RESULTS

The systolic and diastolic anterior-posterior diameter/√BSA, transversal diameter/√BSA, MAA/BSA converted to a natural logarithm (Ln(MAA/BSA)), and MAC/√BSA was significantly higher in the MMVD group than the control group, whereas flattening ratio values and contraction ratio of the MAA was significantly lower. Neither the aortic annulus diameter /√BSA nor the Ln(aortic annulus area/BSA) significantly differed between groups. In the MMVD group, diastolic MAC/√BSA and MAA/BSA correlated significantly with the MAD/√BSA.

CONCLUSIONS

The MVA is larger and rounder in dogs with MMVD than controls. Two-dimensional echocardiographic measures of MAA and MAC correlate well with intraoperative measures of MAD.

Analysis of mitral valve morphology in dogs undergoing mitral valve repair with three-dimensional transesophageal echocardiography

INTRODUCTION

Information about real-time three-dimensional (3D) transesophageal echocardiography (TEE) for the evaluation of canine mitral valve morphology is lacking in veterinary medicine.

OBJECTIVES

To evaluate the feasibility of 3D TEE for the evaluation of canine mitral valves and whether there was a difference in mitral valve morphology between American College of Veterinary Internal Medicine (ACVIM) stages.

ANIMALS

Thirty-one dogs were evaluated, including nine dogs classified as ACVIM stage B2, 15 as stage C, and seven as stage D.

MATERIALS AND METHODS

Three-dimensional TEE was performed after anesthetic induction for mitral valve surgery, and the 3D geometry of the mitral valve apparatus was measured.

RESULTS

The intraclass correlation coefficient was good in both inter- and intraobserver analyses of the 3D measurements of mitral valve annulus geometry and excellent in both inter- and intraobserver analyses in the 3D measurements of mitral valve annular and leaflet sizes. Annulus height to commissural width ratio of stage D dogs showed significantly lower values than B2 dogs (B2: 14.2% [9.1-20.5%]; C: 10.6% [6.5-24.1%]; D: 9.5% [4.7-13.8%]). The aortic-mitral angle of stages C and D were significantly flatter than stage B2 (B2: 122.32 ± 9.39; C: 133.66 ± 8.43; D: 140.70 ± 10.70).

CONCLUSIONS

Real-time 3D echocardiography using TEE is a feasible method to evaluate the morphology of the mitral valve in dogs. The saddle shape of the mitral annulus and aortic-mitral angle were flatter in stage D. Further studies are required to understand the pathology of mitral valve disease in dogs.

Preliminary Outcome of a Novel Edge-to-Edge Closure Device to Manage Mitral Regurgitation in Dogs

Background: Veterinary management of mitral valve regurgitation due to mxyomatous valve disease in dogs is limited to medical treatments, which only postpones the onset of congestive heart failure or alleviates clinical symptoms. Most surgical procedures to manage this condition in humans require cardiopulmonary bypass and have a high risk of complications.

Animals: Eight dogs with naturally occurring mitral valve regurgitation.

Methods: Prospective observational study. All dogs were treated with a novel edge-to-edge transcatheter device named ValveClamp. The total surgical procedural time and total catheterization time were recorded. Echocardiographic variables measured pre- and post-procedure were compared using Wilcoxin-signed rank test with a P < 0.05 considered significant. Data were expressed as median and interquartile range and absolute numbers and percentages.

Results: The procedural success rate was 100% and all the dogs survived without complications. The median (interquartile range) total surgical procedural time was 86.5 (76–96.2) minutes and catheterization time was 23.5 (22–33.8) minutes. Echocardiography revealed a significant reduction in mitral regurgitation severity in all dogs following the procedure based on both a reduced mitral regurgitant maximum jet area (P = 0.012) and a reduced mitral regurgitant maximum jet area to left atrial area (P = 0.018).

Conclusion: The ValveClamp device is effective at reducing the severity of mitral regurgitation in dogs with naturally occurring myxomatous valve disease.

Comparison of the mitral valve morphologies of Cavalier King Charles Spaniels and dogs of other breeds using 3D transthoracic echocardiography

Background

Myxomatous mitral valve disease (MMVD) is more prevalent in Cavalier King Charles Spaniels (CKCSs) compared to dogs of other breeds at a given age. Abnormal valvular stress is thought to contribute to the development and progression of MMVD, and a relationship exists between mitral valve (MV) morphology and stress acting on the valve.

Objectives

To determine whether the MV morphology of healthy adult CKCSs differs from the morphology of healthy adult dogs of other breeds determined by RT‐3DTTE.

Animals

Thirty‐five healthy CKCSs and 41 healthy dogs of other breeds.

Methods

Prospective cross‐sectional study. Dogs underwent physical examination, conventional echocardiography, and RT‐3DTTE. RT–3DTTE datasets were analyzed using dedicated software for MV morphologic analysis. Morphologic variables were compared between CKCSs and dogs of other breeds.

Results

The MV of healthy CKCSs had a smaller annulus height (0.46 ± 0.11 vs. 0.56 ± 0.17; P = .0021), tenting height (0.26 ± 0.12 vs. 0.42 ± 0.18; P < .001), tenting area (0.42 ± 0.15 vs. 0.79 ± 0.34; P < .001), normalized tenting volume (0.09 [0.05–0.13] vs. 0.14 [0.10–0.20]; P < .001), and normalized area of the posterior leaflet (0.57 ± 0.15 vs. 0.66 ± 0.18; P = .016) compared to healthy dogs of other breeds; this results in CKCSs having a flatter MV with reduced tenting, compared to the MV of other breeds.

Conclusions and Clinical Importance

These morphologic features could confer a mechanical disadvantage and play a role in the predisposition of CKCSs to the early development of MMVD.

Review of Diagnostic and Therapeutic Approach to Canine Myxomatous Mitral Valve Disease

The most common heart disease that affects dogs is myxomatous mitral valve disease. In this article, we review the current diagnostic and therapeutic approaches to this disease, and we also present some of the latest technological advancements in this field.