title: R-R interval variations influence the degree of mitral regurgitation in dogs with myxomatous mitral valve disease.
abstract: Mitral regurgitation (MR) due to myxomatous mitral valve disease (MMVD) is a frequent finding in Cavalier King Charles Spaniels (CKCSs). Sinus arrhythmia and atrial premature complexes leading to R-R interval variations occur in dogs. The aim of the study was to evaluate whether the duration of the R-R interval immediately influences the degree of MR assessed by echocardiography in dogs. Clinical examination including echocardiography was performed in 103 privately-owned dogs: 16 control Beagles, 70 CKCSs with different degree of MR and 17 dogs of different breeds with clinical signs of congestive heart failure due to MMVD. The severity of MR was evaluated in apical four-chamber view using colour Doppler flow mapping (maximum % of the left atrium area) and colour Doppler M-mode (duration in ms). The influence of the ratio between present and preceding R-R interval on MR severity was evaluated in 10 consecutive R-R intervals using a linear mixed model for repeated measurements. MR severity was increased when a short R-R interval was followed by a long R-R interval in CKCSs with different degrees of MR (P<0.005 when adjusted for multiple testing). The relationship was not significant in control dogs with minimal MR and in dogs with severe MR and clinical signs of heart failure. In conclusion, MR severity increases in long R-R intervals when these follow a short R-R interval in CKCSs with different degrees of MR due to asymptomatic MMVD. Thus, R-R interval variations may affect the echocardiographic grading of MR in CKCSs.
authors: Department of Veterinary Disease Biology, University of Copenhagen, Ridebanevej 9, 1870 Frederiksberg, Denmark.
authors: M J
authors: MJ
authors: Reimann
authors: Department of Cardiology, Odense University Hospital, Sønder Boulevard, 5000 Odense C, Denmark.
authors: J E
authors: JE
authors: Møller
authors: Department of Clinical Sciences, Swedish University of Agricultural Sciences, 7054, 750-07 Uppsala, Sweden.
authors: J
authors: J
authors: Häggström
authors: Laboratory of Applied Statistics, Department of Mathematical Sciences, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors: B
authors: B
authors: Markussen
authors: Department of Veterinary Disease Biology, University of Copenhagen, Ridebanevej 9, 1870 Frederiksberg, Denmark.
authors: A E W
authors: AE
authors: Holen
authors: Department of Veterinary Disease Biology, University of Copenhagen, Ridebanevej 9, 1870 Frederiksberg, Denmark.
authors: T
authors: T
authors: Falk
authors: Department of Veterinary Disease Biology, University of Copenhagen, Ridebanevej 9, 1870 Frederiksberg, Denmark. Electronic address: lihol@sund.ku.dk.
authors: L H
authors: LH
authors: Olsen
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000503:physiopathology*; D004285:Dogs; D004452:Echocardiography / Q000662:veterinary; D005260:Female; D006333:Heart Failure / Q000503:physiopathology / Q000662:veterinary; D008297:Male; D008943:Mitral Valve / Q000503:physiopathology; D008944:Mitral Valve Insufficiency / Q000503:physiopathology / Q000662:veterinary*; D008945:Mitral Valve Prolapse / Q000503:physiopathology / Q000662:veterinary; D013045:Species Specificity; D016276:Ventricular Function
keywords: Animal model; Cavalier King Charles Spaniel; Mitral regurgitation; R-R interval variations; Sinus arrhythmia