Assessment of left and right ventricular systolic function in dogs with multicentric lymphoma.

OBJECTIVE: Myocardial dysfunction in cardio-oncology is generally thought to be related to the cardiotoxicity of chemotherapy treatment. However, it is known that some tumors have direct effects on myocardial function. These effects have already been studied in man, but there are no publications of these of the effects in dogs. Novel advanced echocardiographic techniques may allow early detection of myocardial dysfunction when compared to conventional echocardiographic techniques. This study aims to assess myocardial systolic function in dogs with multicentric lymphoma prior to initiation of chemotherapy. ANIMALS: Fifteen dogs with multicentric lymphoma and nineteen healthy dogs. METHODS: Case-control study. Dogs with multicentric lymphoma and healthy control dogs underwent physical examination, electrocardiography, systolic blood pressure measurement, standard and speckle tracking echocardiography to assess biventricular systolic function. RESULTS: There were no differences between groups in terms of ejection fraction, fractional shortening, left ventricular systolic and diastolic diameter, tricuspid annular plane systolic excursion, mitral annular plane systolic excursion and fractional area change of the right ventricle (RV). However, there was a reduction in the values of global circumferential strain (p = 0.0003), RV strain (p = 0.01) and RV tissue motion annular displacement (p < 0.05) in the dogs with lymphoma when compared to the control group. CONCLUSIONS: Speckle tracking techniques appear to demonstrate early systolic dysfunction, primarily affecting the RV, in dogs with lymphoma prior to chemotherapy treatment.

Assessment of heart rate turbulence in dogs with myxomatous mitral valve disease.

BACKGROUND: Myxomatous mitral valve degeneration (MMVD) is the most common heart disease affecting small dogs, it reduces cardiac output resulting in compensatory adaptation of the autonomic nervous system. Chronically, it leads to reduced heart rate variability (HRV) which is an accurate marker for autonomic balance. More than two decades ago in human medicine an indicator of autonomic balance that happens after a premature ventricular beat, it was described as heart rate turbulence (HRT). In humans with ischemic heart disease, the absence of HRT has proven to be a more accurate and an independent indicator of mortality than known HRV parameters. Currently, there are very few studies of HRT in dogs and it is still not tested in small dogs within different stages of myxomatous mitral valve disease. AIM: The aim of this study was to assess the HRT indicators, onset and slope, in small dogs with myxomatous mitral valve disease and to statistically test it. METHODS: Dogs under 25 kg had electrocardiogram and echocardiography performed and, in some patients, holter monitoring was carried out. Data were divided into groups B1, B2, C, and D for mean comparison with analysis of variance and Tukey test. In addition, receiver operating characteristic (ROC) curve for differentiating among symptomatic and asymptomatic dogs and for differentiating between remodeled and non-remodeled hearts. The Pearson was executed after correlations of turbulence onset (TO) and turbulence slope (TS) with commonly used echocardiographic parameters. RESULTS: Variance analyses held significant differences in TO and TS between stages B1 from stages C and D, while B2 held similarity to the other groups. In the receiver operating curve was found a very good area under the curve for differentiating among symptomatic and asymptomatic dogs and remodeled and non-remodeled dogs. Few echocardiography parameters held weak correlation with TO while others held weak to moderate correlation with TS. CONCLUSION: In dogs with MMVD and without other diseases, HRT is a feasible indicator for autonomic balance. Our result suggests HRT changes as the MMVD progresses and congestive heart failure is present. More studies with HRT are needed. The number of ventricular premature contractions (VPCs) may be the strongest limitation for the technique.

Congenital Heart Disease in Dogs: A Retrospective Study of 95 Cases.

The aim of the study was to estimate the prevalence of congenital heart diseases in dogs attending 2 veterinary hospitals in Brazil and to identify possible associations between these conditions and epidemiological characteristics. A retrospective study was carried out in the cardiology sections of 2 veterinary hospitals during a period of 70 months from January 2012 and October 2017. Of a total of 6710 dogs that attended the cardiology sections of the hospitals, 109 congenital heart diseases were identified in 95 patients, representing a prevalence of 1.6%. Findings consistent with previous literature included subaortic stenosis and pulmonic stenosis as the most commonly diagnosed conditions, in addition to a higher predisposition of females to patent ductus arteriosus (PDA). In contrast, the novel findings included a higher prevalence of atrial septal defect and a lower prevalence of patent ductus arteriosus. The majority of the animals included were over 1 year of age at the time of diagnosis (67%) especially in the subaortic stenosis group. Also, a predisposition of the Maltese to ventricular septal defect was observed. The information obtained in the present study contributes to research that describes epidemiological characteristics of dogs with congenital heart disease in a previously unreported location.

Assessment of longitudinal systolic function using tissue motion annular displacement in healthy dogs.

INTRODUCTION: Left ventricular systolic function is one of the main parameters studied in echocardiography. Longitudinal systolic function, however, is less commonly evaluated in routine examinations but may provide early information on systolic dysfunction. The movement of the mitral annulus toward the apex has already been determined as a method for evaluation of longitudinal systolic function in dogs, but the study of this movement by speckle tracking with the tissue motion annular displacement (TMAD) technique has not yet been evaluated. ANIMALS: One hundred fifty-three client-owned healthy dogs. METHODS: Cross-sectional study. One hundred fifty-three client-owned healthy dogs underwent physical examination, electrocardiography, blood pressure measurement, and a standard and speckle tracking echocardiography. Systolic function was evaluated by global longitudinal strain (GLS) and TMAD. These parameters were compared with the standard echocardiographic data. RESULTS: A correlation was found between GLS, TMAD, and body weight. Tissue motion annular displacement and GLS were significantly correlated (p < 0.001) with other surrogates of systolic function, including ejection fraction and fractional shortening. There were no differences in TMAD between sexes. The coefficient of variation (CV) of the intraobserver evaluation in the global TMAD (CV 4.44) was slightly higher than that in the GLS (CV 3.74). Also, TMAD was not influenced by heart rhythm and could be acquired more rapidly than GLS. CONCLUSIONS: Tissue motion annular displacement is a rapid and reproducible method for the assessment of left ventricle longitudinal function in healthy dogs. However, more studies are needed to validate the real clinical applicability of TMAD in animals with heart diseases.

Using the Oculocardiac Reflex to Characterize Autonomic Imbalance in a Naturally Occurring Canine Model of Valvular Insufficiency.

Congestive heart failure (CHF) is characterized by reduced heart rate variability. Although various methods to achieve parasympathetic withdrawal and sympathetic activation have been documented, stimulation of the vagal nerve (that is, vagal maneuvers) has not often been used to assess the autonomic impairment associated with disease progression in veterinary species. In this study, we investigated cardiac autonomic control in a naturally occurring canine model of mitral insufficiency by means of individual responses to oculocardiac reflex. Indices of heart rate variability were calculated from 5-min ECG tracings obtained before and after ocular compression. After compression, significant increases in the standard deviation of RR intervals, root mean square of the successive differences in RR intervals, and vasovagal tonus index were documented in healthy control animals. In addition, these indices were increased in asymptomatic dogs with remodeled hearts, but no variation occurred in symptomatic animals. Although only the percentage change in vasovagal tonus index differed significantly between controls and diseased dogs, all other parameters showed a tendency to behave the opposite way in the symptomatic group as in the control and asymptomatic groups. Our results document CHF-dependent autonomic dysfunction in a canine model of valve insufficiency.