Surgical technique for mitral valve repair in dogs using a novel method to anchor artificial chordae tendineae with emphasis on key intraoperative decision points

Objectives Surgical options for mitral valve repair in dogs are unstandardized and influenced by various factors. This study describes a four-point surgical technique (MI-4) to reduce mitral regurgitation and provides data from a study of dogs with 12 months of follow up.Methods Twenty-five dogs with stages C or D mitral insufficiency were treated by one of two surgeons using the MI-4 procedure at Ueno no Mori Animal Hospital between October 2021 and May 2023. The surgical technique comprised: (I) determination of the valve annulus dimensions by measuring between the trigones, (II) triad-anchored chordae tendinea reconstruction, (III) determination of the appropriate position and number of chordae tendineae on the leaflets, and (IV) appropriate height determination. The regurgitation percentage was measured using B-mode color Doppler flow in the atrium in the four-chamber left long-axis view.Results There were no intraoperative complications, and 23, 23, and 18 dogs were successfully re-evaluated at 1, 6, and 12 months, respectively (5 dogs have not yet reached the 12-month follow-up point). The regurgitation percentage decreased from 73.0% (interquartile range, 58.1-81.5%) preoperatively to 2.1% (0.0-8.8%), 4.6% (0.1-10.8), and 1.3% (0.0-7.1) at 1, 6, and 12 months postoperatively, respectively. All surviving dogs improved clinically.Conclusion The MI-4 surgical technique was performed in dogs with mitral valve insufficiency with no significant complications. The surgery reduced the regurgitation percentage postoperatively, with benefits seen at least 12 months after surgery.