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Simple Summary: Dilated cardiomyopathy is a cardiac disorder most commonly observed in specific dog breeds and is characterized by diffuse left ventricular systolic dysfunction and left ventricular enlargement. Recent studies have reported a potential connection between diet and dilated cardiomyopathy, and some studies have shown a positive effect of diet change on cardiac function and prognosis in dogs with diet-related dilated cardiomyopathy. However, these reports were from large-breed dogs and did not include detailed assessments of myocardial function, such as two-dimensional speckle-tracking echocardiography. We report an overview of our experience in a small-breed dog with a clinical diagnosis of dilated cardiomyopathy, in which dietary modification resulted in improved cardiac enlargement and myocardial dysfunction evaluated by two-dimensional speckle-tracking echocardiography. We suggest that it is necessary to suspect a dietary association with dilated cardiomyopathy, even in small-breed dogs. Furthermore, the prognosis for diet-related dilated cardiomyopathy in small-breed dogs may also be as good as in previous reports of large-breed dogs when changing to appropriate diets. An 11-year-old intact female Papillion weighing 2.1 kg was referred to our institution with the main complaint of shallow, rapid breathing. At the first visit (day 0), although clinical signs improved due to the use of medication from the primary hospital, transthoracic radiography and echocardiography revealed left heart enlargement and left ventricular dysfunction. A clinical diagnosis of dilated cardiomyopathy (DCM) was made and oral administration of pimobendan, temocapril, and taurine was initiated. However, on day 10, the respiratory status worsened and furosemide was prescribed. On day 54, no significant improvement in heart size was observed. Additionally, the diet that this patient received met the recommendation for diet-related DCM by the U.S. Food and Drug Administration, and the patient's diet was changed from a grain-free diet to a grain-containing diet. On day 1191, the patient's respiratory status was stable and no clinical signs were observed. Transthoracic radiography and echocardiography revealed an improvement in left heart size. Additionally, improvements in the left and right ventricular myocardial strains were observed after changing the diet. We suggest that it may be necessary to suspect a dietary association with dilated cardiomyopathy, and a good prognosis might be expected by dietary modification, even in small-breed dogs. [ABSTRACT FROM AUTHOR]

Real-time three-dimensional echocardiography (RT3DE) enables a noninvasive assessment of right ventricular (RV) morphology. However, no study has evaluated the relationship between RV function obtained by RT3DE and RV pressure-volume loops. This hypothesis-driven, experimental study aimed to assess the utility of RT3DE in the evaluation of RV morphology and function. Ten anesthetized beagle dogs sequentially underwent dobutamine infusion, acute infusion of lactated Ringer's solution, and furosemide administration to alter RV contractility and loading conditions. RV pressure-volume loop-derived hemodynamic measurements and echocardiography, including two-dimensional speckle-tracking echocardiography and RT3DE, were performed in each study protocol. Bland–Altman analysis showed strong agreement in RV volume, ejection fraction, and stroke volume obtained by right heart catheterization and RT3DE. Multiple regression analyses revealed that the peak myocardial velocity of the lateral tricuspid annulus (RV s') and global RV longitudinal strain rate were significantly associated with end-systolic elastance (adjusted r2 = 0.66, p < 0.001). RV s', RV free wall longitudinal strain, and RT3DE-derived stroke volume/end-systolic RV volume ratio were associated with RV pressure-volume loops-derived end-systolic/arterial elastance ratio (adjusted r2 = 0.34, p < 0.001). RT3DE could detect the changes in catheterization-derived RV volume with a strong agreement and might be useful in estimating RV-pulmonary arterial coupling. [ABSTRACT FROM AUTHOR]

Background: Hypertrophic cardiomyopathy (HCM), a primary disorder of the myocardium, is the most common cardiac disease in cats. However, determination of layer‐specific myocardial function with 2D speckle‐tracking echocardiography in cats with asymptomatic HCM has not yet been reported. Objectives: To quantitatively measure layer‐specific myocardial function of asymptomatic cats with HCM. Animals Ten client‐owned, asymptomatic cats with obstructive HCM and 13 healthy cats. Methods: A retrospective, case‐control study. Cats underwent assessment of layer‐specific myocardial function (whole, endocardial, and epicardial) in the longitudinal and circumferential directions by using 2D speckle‐tracking echocardiography. Results: Longitudinal strains were significantly lower in cats with HCM than controls in the whole (−15.5% vs −19.1%), endocardial (−18.3% vs −21.8%), and epicardial (−13.1% vs −16.8%) layers. Circumferential strains in whole and epicardial layers also were significantly lower in cats with HCM as compared with controls (−15.0% vs −20.2% and − 4.4% vs −9.4%, respectively). However, no significant difference was found between cats with HCM and controls in the global circumferential strain in the endocardial layer (−31.2% vs −34.2%). The circumferential endocardial‐to‐epicardial strain ratio was significantly higher in cats with HCM than in controls (6.1 vs 3.5). Conclusions and Clinical Importance: Layer‐specific myocardial function assessed by 2D speckle‐tracking echocardiography differed in asymptomatic cats with obstructive HCM compared to controls despite their apparently normal systolic function, as determined by conventional echocardiography. The maintained endocardial circumferential strain and higher circumferential endocardial‐to‐epicardial strain ratio may reflect compensation for occult systolic dysfunction in cats with obstructive HCM. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The objective of this study was to evaluate the effect of age on myocardial function assessed by two-dimensional speckle-tracking echocardiography (2D-STE) in healthy dogs. Animals: Thirty-two healthy Beagles were used. Methods: Myocardial function was assessed in each dog by using 2D-STE, and the results were compared between young and old dogs. Results: The myocardial deformations in systole, besides the apical rotation rate, were not significantly different between young and old dogs. In contrast, the early diastolic circumferential strain rate, basal rotation rate, and torsion rate were significantly lower in old dogs than in young dogs (P = 0.03, P = 0.033, and P = 0.015, respectively). Late diastolic longitudinal and radial strain rates were significantly higher in old dogs than in young dogs (P = 0.002 and P = 0.018, respectively). Conclusions: Young and old dogs showed similar systolic myocardial deformations, but significant differences in the values of some diastolic deformation variables were found between young and old dogs, highlighting the need for using age-matched control subjects in studies of diastolic function. [Copyright &y& Elsevier]

Abstract: Objective: The objective of this study was to evaluate the influence of heart rate (HR) on myocardial function assessed by two-dimensional speckle-tracking echocardiography (2D-STE) in healthy dogs. Animals: Thirteen healthy beagle dogs. Methods: Animals were anesthetized and HR was controlled with right atrial pacing. Myocardial function of each dog was assessed using 2D-STE at pacing rates of 120, 140, 160, and 180 bpm. Results: All strain and strain rate variables in the longitudinal, circumferential, and radial directions were not significantly different between pacing rates. Peak early diastolic torsion rate at 180 bpm was significantly increased compared with that at 120 bpm (P = 0.003). Conclusion: Torsion rate in early diastole was elevated at 180 bpm, which may reflect improved myocardial relaxation with higher HR. Changes in left ventricular torsion during tachycardia may play an important role in preserving stroke volume in the presence of shortened ejection and filling times. [Copyright &y& Elsevier]

Abstract: Objective: The objective of this study was to clinically assess myocardial deformations in dogs with chronic mitral valve insufficiency (CMVI) using two-dimensional speckle-tracking echocardiography (2D-STE). Animals: 87 dogs with CMVI. Methods: Dogs were placed into 1 of 3 classes, based on the International Small Animal Cardiac Health Council classification. In addition, 20 weight- and age-matched healthy dogs were enrolled as controls. The dogs were examined for myocardial deformations using 2D-STE, and strain and strain rate in the longitudinal, circumferential, and radial directions were evaluated. Results: Class II and III dogs had higher circumferential strain than class I dogs (P = 0.002 and P = 0.001, respectively) and controls (P < 0.001 and P < 0.001, respectively). Class III dogs had higher radial strain than class I dogs (P = 0.001) and controls (P < 0.001). Class III dogs had higher radial strain rate than class I dogs (P = 0.006) and controls (P = 0.001). Other deformations, including longitudinal deformations, were not significantly different between classes of CMVI or between CMVI dogs and controls. Conclusions: In the clinical progression of CMVI in dogs, myocardial deformations, as assessed by 2D-STE, differed according to myocardial contractile direction. Thus, assessments of multidirectional myocardial deformations may be important for better assessment of clinical cardiac function in dogs with CMVI. [Copyright &y& Elsevier]

Simple Summary: The endomyocardial form of restrictive cardiomyopathy, a primary disorder of the myocardium, is one of the diseases with poor prognosis in cats. While two-dimensional speckle-tracking echocardiography has been known to identify myocardial deformations, its function relative to cats with the endomyocardial form of restrictive cardiomyopathy has yet to be characterized. We hypothesized that both the left and right myocardial functional abnormalities may occur in cats with the endomyocardial form of restrictive cardiomyopathy, causing this disease pathophysiology and clinical status. In the current study, cats were assessed for layer-specific myocardial function (whole, endocardial, and epicardial) in the left ventricular longitudinal and circumferential directions, and right ventricular longitudinal direction, via two-dimensional speckle-tracking echocardiography. Our study indicated that cats with restrictive cardiomyopathy have reduced left ventricular myocardial function. Notably, left ventricular systolic circumferential endocardial strain and circumferential endocardial-to-epicardial strain ratio were lower in cats with restrictive cardiomyopathy. Furthermore, some right ventricular myocardial deformations were also differerent in cats with restrictive cardiomyopathy. Myocardial function assessed by two-dimensional speckle-tracking echocardiography could reveal left and right myocardial dysfunction. The endomyocardial form of restrictive cardiomyopathy (EMF-RCM), a primary disorder of the myocardium, is one of the diseases with poor prognosis in cats. We hypothesized that both the left and right myocardial functional abnormalities may occur in cats with EMF-RCM, causing this disease pathophysiology and clinical status. Out of the 25 animals included in this study, 10 were client-owned cats with EMF-RCM, and 15 were healthy cats. In this study, cats were assessed for layer-specific myocardial function (whole, endocardial, and epicardial) in the left ventricular longitudinal and circumferential directions, and right ventricular longitudinal direction, via two-dimensional speckle-tracking echocardiography (2D-STE). Cats with EMF-RCM had depressed left ventricular myocardial deformations both in systole (whole longitudinal strain, epicardial longitudinal strain, and endocardial circumferential strain) and diastole (early and late diastolic longitudinal strain rates, and late diastolic circumferential strain rate) compared to controls. Furthermore, some right ventricular myocardial deformations (systolic longitudinal strain in epicardial layers, and endocardial-to-epicardial strain ratio) were significantly differerent in cats with EMF-RCM. Myocardial function assessed by 2D-STE could reveal left and right myocardial dysfunction. [ABSTRACT FROM AUTHOR]