Echocardiographic measurement of the mitral valve in normal Cavalier King Charles spaniels: repeatability, optimal future study methods, and preliminary reference intervals.

INTRODUCTION/OBJECTIVES: Cavalier King Charles spaniels (CKCS) are ideal candidates for longitudinal study of myxomatous mitral valve (MV) disease and stage B1 clinical trials; however, the optimization of MV measurement acquisition and repeatability must be better defined to realize this potential. Additionally, breed-specific reference ranges for CKCS MV measurements are lacking. Study objectives were to assess measurement repeatability and define optimal methods for the longitudinal study of echocardiographic MV anatomy and to define preliminary, two-dimensional echocardiographic reference ranges for MV measurements in CKCS.

ANIMALS

Forty CKCS between 10 and 24 months old.

MATERIALS AND METHODS

Pre- and post-sedation two-dimensional echocardiographic images optimized for the MV were obtained. The length, width, and area of the anterior and posterior leaflets and the diameter of the MV annulus at end-diastole and end-systole were measured. Measurement repeatability was assessed using % coefficient of variation and repeatability coefficients.

RESULTS

Intraoperator repeatability was best for the operator with previous MV measurement experience, with comparable results for the experienced operator measuring the second operator's images, mimicking a core echocardiography laboratory setting. Except for MV annulus diameter at end-systole, sedation had no significant effect on any MV measurements, nor did it impact measurement repeatability. Preliminary, breed-specific reference ranges were defined for the population, with CKCS often noted to have a larger annular diameter at end-systole than end-diastole.

CONCLUSIONS

Optimal methods for longitudinal study of the MV in CKCS have been proposed, as have two-dimensional preliminary echocardiographic reference ranges for CKCS MV measurements. The MV annulus in CKCS may differ from other breeds.