Survival Characteristics and Prognostic Variables of Dogs with Mitral Regurgitation Attributable to Myxomatous Valve Disease

BackgroundSyncope is a transient loss of consciousness occasionally occurring in dogs with advanced myxomatous mitral valve disease (MMVD).Objective(1) To study ECG changes during syncopal episodes in dogs with advanced MMVD and (2) to compare the occurrence of arrhythmias and changes in heart rate variability (HRV) between dogs with advanced MMVD with and without a history of syncope.AnimalsForty‐three privately owned dogs (<15 kg) with advanced MMVD: 21 with and 22 without a history of syncope.MethodsProspective study with dogs recruited for an evaluation including history, physical examination, echocardiography, and arrhythmia and HRV analysis performed on 24‐hour Holter recordings.ResultsA syncopal episode was observed during Holter monitoring in 4 dogs: 3 dogs had sinus rhythm and 1 dog had sinus arrest followed by escape rhythm. An arrhythmia variable representing sinus arrhythmia was significantly lower in dogs with a history of syncope than in those without (P = .008). Eight of 26 HRV variables were significantly different between dogs with and without a history of syncope.Conclusions and Clinical ImportanceCompared with dogs without a history of syncope, dogs with advanced MMVD and a history of syncope did not have a higher occurrence of arrhythmias, but had less sinus arrhythmia, and had changes in HRV variables representing decreased overall HRV, decreased parasympathetic, and increased sympathetic modulation of heart rate.

Section: Discussionsupporting

confidence: 49%

Holter Monitoring of Small Breed Dogs with Advanced Myxomatous Mitral Valve Disease with and without a History of Syncope

Rasmussen

Falk

Petrič

et al. 2014

“…Degenerative mitral valve disease (DMVD) characterized by myocardial dysfunction with eccentric cardiac remodeling is the leading cause of heart failure in small breed dogs 1, 2. Myocardial systolic or diastolic dysfunction accrues from histopathologic changes that cause myocardial decompensation, which in turn induces clinical signs such as cough, dyspnea, and exercise intolerance 3, 4, 8, 9, 10.…”

Section: Discussionmentioning

confidence: 99%

“…The most common cause of congestive heart failure in small breed dogs is degenerative mitral valve disease (DMVD) characterized by poor coaptation of mitral valve cusps, leading to mitral regurgitation 1, 2. In chronic heart diseases, accurate evaluation of myocardial function is important, because it aids clinicians in planning medical treatment and formulating a prognosis 3, 4.…”

mentioning

confidence: 99%

Pathologic Manifestations on Surgical Biopsy and Their Correlation with Clinical Indices in Dogs with Degenerative Mitral Valve Disease

Lee

Mizuno

et al. 2015

BackgroundEvaluation of myocardial function is clinically challenging in dogs with degenerative mitral valve disease (DMVD). Although myocardial dysfunction is caused by pathologic degeneration, histopathologic progression is poorly understood.ObjectivesTo characterize myocardial and pulmonary pathologic changes according to severity in dogs with naturally occurring DMVD, and to investigate whether or not pathologic degeneration is reflected by traditional clinical indices.AnimalsOne hundred and seventeen dogs with naturally occurring DMVD.MethodsProspective observational study. Biopsied left atrium (LA), left ventricle (LV), and lung were evaluated histologically, and an attempt was made to correlate pathologic findings with clinical indices.ResultsSevere myocardial changes were observed in all International Small Animal Cardiac Health Council classes. In the lung, heart failure cell levels were significantly increased in class III patients (P < .0001). In a paired comparison, the LA showed significantly more severe degeneration than the LV, including myocardial fatty replacement, immune cell infiltration, and interstitial fibrosis (P < .0001). In contrast, myocardial cells were more hypertrophied in the LV than in the LA (P < .0001). Left ventricular end‐diastolic dimension (LVEDd) was associated with fatty replacement (P = .033, R 2 = 0.584) and myocardial vacuolization (P = .003, R 2 = 0.588) in the LA.Conclusions and Clinical ImportanceIn DMVD, although severe pathologic changes may be evident even in early stages, there may be pathologic discrepancy between the LA and the LV. Myocardial degeneration may be reflected by clinical indices such as LVEDd and EF.

“…Systolic function has been suggested to decrease in dogs with naturally acquired MMVD2, 3 and in dogs with experimentally induced MR 20, 21. However, identification of systolic dysfunction is challenging in dogs with MMVD22; EF, FS, and PEP/ET at rest and dobutamine infusion could not detect systolic dysfunction.…”

Section: Discussionmentioning

confidence: 99%

Dobutamine Stress Echocardiography for Assessment of Systolic Function in Dogs with Experimentally Induced Mitral Regurgitation

Suzuki

Matsumoto

Teshima

et al. 2014

BackgroundSystolic dysfunction is associated with poor outcomes in dogs with myxomatous mitral valve disease. However, assessment of systolic variables by conventional echocardiographic methods is difficult in these dogs because of mitral regurgitation (MR).HypothesisWe hypothesized that assessment of systolic function by dobutamine stress may identify systolic dysfunction in dogs with MR, and that 2‐dimensional speckle‐tracking echocardiography (2D‐STE) could quantitatively evaluate myocardial function.AnimalsAnesthetized dogs with experimentally induced MR.MethodsDogs were examined for systolic myocardial deformations using 2D‐STE during dobutamine infusion before and 3 and 6 months after MR induction. We evaluated peak systolic rotation and rotation rate in each basal and apical view; peak systolic torsion and torsion rate were also calculated.ResultsInvasive peak positive first derivatives of left ventricular pressure (dp/dt) were significantly decreased in dogs 6 months after induction of MR compared with pre‐MR results. After 3 and 6 months of MR, dogs had diminished peak systolic torsion values and torsion rates in response to dobutamine infusion compared with pre‐MR results (3 months, P < .001 and P = .006; 6 months, P = .003 and P = .021). These results were significantly correlated with overall invasive dp/dt (r = 0.644, P < .001; r = 0.696, P < .001).Conclusions and Clinical ImportanceDecreased torsion during dobutamine infusion in dogs with MR may reflect latent systolic dysfunction. Dobutamine infusion, therefore, may be useful for the assessment of systolic function in dogs with MR.