Effects of mitral valve repair on valvular geometry and hemodynamics in dogs with myxomatous mitral valve disease

Objective: To investigate the effects of mitral valve repair on the geometry of the mitral valve complex, hemodynamics, and cardiac function of dogs with myxomatous mitral valve disease (MMVD).Study design: Retrospective cohort study.Sample population: Dogs (n = 77) with stage C MMVD undergoing mitral valve repair under cardiopulmonary bypass.Methods: Mitral valve geometry and cardiac function were assessed using echocardiography preoperatively, 1 week postoperatively and 3 months postoperatively. Results: The coaptation length (0 [0-0] vs. 7 [6-8.5] mm, p < .001) and forward stroke volume index (1.5 +/- 0.4 vs. 2.3 +/- 0.6 mL/kg, p < .001) were higher at 3-months postoperatively than preoperatively, whereas the vertebral heart score (12.3 +/- 1.2 vs. 10.8 +/- 0.8 V, p < .001), left atrial-to-aortic ratio (2.2 +/- 0.7 vs. 1.2 +/- 0.3, p < .001), peak velocity of early diastolic transmitral flow (144 +/- 34 vs. 91 +/- 18 cm/s, p < .001), and regurgitant volume index (11.3 [8.2-14.0] vs. 1.6 [0.95-2.35] mL/kg, p < .001) were lower. Postoperatively, mitral valve geometry was completely changed within 1 week, whereas changes in vertebral heart score lasted for 3 months.Conclusion: Mitral valve repair changed valvular geometry and improved hemodynamics as assessed by follow-up echocardiography.Clinical significance: This study acts as reference for surgeons and cardiologists considering or evaluating the effects of mitral valve repair in dogs and provides useful data for the enhancement of relevant surgical techniques and the selection of relevant pre-and postoperative observations.