Veterinary Student Colorado State University Fort Collins, CO, United States
Abstract:
Background: Mitral annular dilation contributes to worsening mitral regurgitation (MR) by causing separation of the mitral leaflets (Carpentier type I defect). Widening of the vena contracta along the zone of leaflet apposition could reflect this mechanism of secondary functional mitral regurgitation (FMR) and may have implications for prognosis and mitral intervention in dogs with degenerative mitral valve disease (DMVD).Hypothesis: The percent-ratio of vena contracta width (VCW) to mitral valve commissural diameter (MVCD) increases with disease stage in dogs with DMVD. Animals: Fifty-four client-owned dogs with ACVIM stage B1 (n=17), stage B2 (n=18), or stage C (n=19) DMVD. Inclusion criteria were ≥ 5 years of age, body weight ≤ 25 kg, and systolic blood pressure
Methods: Echocardiograms were performed by a cardiologist (BMP) and measurements performed by a single investigator (ZTE). Measurements of mid-systolic MVCD were obtained from left apical commissural view and normalized to aortic valve diameter. VCW was measured from the same mid-systolic left apical commissural view. Differences between disease stage were determined by one-way ANOVA.
Results: The normalized MVCD increased (p=0.0002) with disease stage (B1=1.50, B2=1.77, C=2.17). The percent-ratio of VCW to MVCD increased (p<0.0001) with disease stage (B1=19.7%, B2=37.0%, C=51.8%)
Conclusions: Widening of the vena contracta relative to the MVCD supports a conclusion that mitral annular dilation and resultant secondary FMR (Carpentier type I defect) is associated with progression of DMVD. This mechanism may have implications for prognosis as well as predict MR reduction in dogs undergoing mitral intervention.
