Ultrasonographic Assessment of Regional Radial and Longitudinal Systolic Function in Healthy Awake Dogs

Assessment of longitudinal systolic function using tissue motion annular displacement in dogs with degenerative mitral valve disease

INTRODUCTION

Although degenerative mitral valve disease (DMVD) is essentially a disorder of the valve, the progression of the disease leads to structural myocardial changes that may compromise left ventricular systolic function. Tissue motion annular displacement (TMAD) is a surrogate for longitudinal fiber function based on speckle tracking assessment of the movement of the mitral annulus toward the apex during systole. The aim of this study was to evaluate longitudinal systolic function with TMAD in dogs with DMVD.

ANIMALS

Ninety-four dogs with DMVD and 32 healthy dogs.

METHODS

Prospective cross-sectional observational study. Dogs with DMVD of various American College of Veterinary Internal Medicine classification stages and healthy control dogs underwent physical examination, electrocardiography, systolic blood pressure measurement, as well as a standard and speckle tracking echocardiography. Global longitudinal strain (GLS) and TMAD were used to assess longitudinal systolic function.

RESULTS

The global TMAD_mm and global TMAD_% were higher in American College of Veterinary Internal Medicine B2 animals than in the stage CD. Global TMAD _(mm/kg,_mm/bodyweight3, _mm/m²) were correlated with GLS and ejection fraction. Global TMAD _(mm/kg,_mm/m²,%) and GLS were influenced by sex. In addition, systolic blood pressure influenced GLS (P < 0.01; r = -0.23), global TMAD_mm/kg (P = 0.017; r = -0.21) and global TMAD_mm/m² (P = 0.031; r = -0.19). Tissue motion annular displacement was fast to be performed and produced good repeatability in dogs with DMVD.

CONCLUSIONS

Global TMAD _(mm,%), was reduced in DMVD dogs with clinical signs of heart failure compared with stage B2. Tissue motion annular displacement was shown to be a repeatable technique for evaluation of longitudinal systolic function in dogs with DMVD.

Screening for dilated cardiomyopathy in dogs

BACKGROUND

Dilated cardiomyopathy (DCM) is the most common cardiac disease in large breed dogs. The disease can start with arrhythmias or with systolic dysfunction of the myocardium.

OBJECTIVE

To describe screening methods for DCM in various breeds and provide a new, modified staging system.

RECOMMENDATIONS

Screening for occult DCM should start at three years of age and use Holter monitoring in Boxers and Dobermans and might be useful also in other breeds. Single ventricular premature complexes (VPCs) can be detected in many healthy dogs, but healthy animals typically have <50 VPCs in 24 h and demonstrate minimal complexity most often occurring only as single ectopic beats. In general, >100 VPCs in 24 h was recommended as the cut-off value for establishing a diagnosis of DCM. However, there are breed-specific recommendations related to Holter recording diagnosis of DCM in Dobermans and Boxers. Yearly screening over the life of a dog is recommended, as a one-time screening is not sufficient to rule out the future development of DCM. Several echocardiographic methods such as M-mode derived measurements, the measurement of the left ventricular (LV) volume by Simpson's method of discs (SMOD), and E-point to septal separation (EPSS) are recommended for screening purposes. The value of additional tests such as cardiac biomarkers (troponin I and N-terminal pro-B-type natriuretic peptide) as well as a 5-min resting electrocardiogram (ECG) or newer echocardiographic methods such as strain measurements is discussed.

CONCLUSION

This review suggests some guidelines for screening for DCM in various breeds.

Left Ventricular Function During Epinephrine Stimulation and Hypothermia: Effects at Spontaneous and Paced Heart Rates in a Porcine Model

Postcardiac arrest patients treated with hypothermia, frequently require vasopressors and inotropic medication. The aim of this experimental study was to investigate the effect of epinephrine on left ventricular (LV) function during hypothermia. In an open-chest porcine model, seven animals were equipped with LV micromanometer and epicardial ultrasound transducers to provide LV pressure, Tau, and wall thickness and thickening velocities in systole (S') and early diastole (e'). Arterial, central venous, and pulmonal artery pressures were recorded. Cardiac output (CO) was measured by transit-time flow probe on the ascending aorta. Hypothermia was induced using a cooling catheter through the femoral vein. Pacemaker leads were attached to the right atrium for pacing. LV volumes were obtained by two-dimensional echocardiography. Measurements were made at normothermia (38°C) and hypothermia (33°C), without and with epinephrine infusion (0.03 μg/kg/min), at spontaneous and paced heart rates (HRs) 120 and 140 beats/min. Hypothermia reduced LV stroke volume (SV). Epinephrine during hypothermia increased the SV with reduced end-systolic volumes. LV dP/dt_max and wall-thickening velocity increased. During normothermia, epinephrine increased CO mainly due to accelerated HR, but during hypothermia, the increased CO resulted from augmented SV and, to a lesser degree, elevated HR. The incomplete relaxation and shortened diastolic filling time and the following reduction in SV seen in hypothermic animals, was repealed by epinephrine. The CO remained elevated also due to a shortened systolic duration, which gave time for complete relaxation during higher HRs. Epinephrine infusion improved systolic and diastolic function during hypothermia, and thereby reversed the effects induced by hypothermia considerably. Epinephrine augmented CO at hypothermia through increases in both SV and HR, in contrast to a mainly HR-dependent effect during normothermia. Systolic duration was shortened, which gave sufficient diastolic duration for complete relaxation. This allowed diastolic filling and maintained CO at elevated HRs.

Diagnostic methods for the canine idiopathic dilated cardiomyopathy: A narrative evidence-based rapid review

Idiopathic dilated cardiomyopathy (DCM) is an important etiology of mortality and morbidity in dogs and its diagnosis relies on systolic dysfunction, chambers dilation, electrical instability and congestion. During the last decades veterinary cardiologists have been joining efforts to obtain diagnostic resources to correctly identify canine DCM in the preclinical stage. Unfortunately, most diagnostic resources have been used with the support of research with weak evidence, without high quality methodologies such as systematic reviews or meta-analysis. Therefore, the support of evidence-based medicine is tailored by empiricism and diagnostic criteria lose'out the ability to properly classify dogs suffering DCM. The presentation of the evidence in medicine is established by multiple sources and the most reliable source has been the presentation of evidence-based medicine from systematic reviews and meta-analysis. Rapid reviews can be interpreted as a pragmatic approach to systematic reviews and although a rapid review follows most of the critical steps of a systematic review to provide timely evidence, some components of a systematic review process are either simplified or omitted. The objective of this narrative evidence-based rapid review is twofold. First: To recognize and to stratify the level of evidence offered by rigorous selected papers about the diagnosis of DCM. Second: To classify the degree of clinical recommendation of the diagnostic resources available.

Quantitative assessment of systolic and diastolic right ventricular function by echocardiography and speckle-tracking imaging: a prospective study in 104 dogs

Our aim was (1) to determine the within-day and between-day variability of several indices of systolic and diastolic right ventricular (RV) function by using conventional echocardiography and speckle-tracking echocardiography (STE) (Study 1), (2) to quantify these variables in a large healthy canine population (n = 104) with Doppler-derived estimated systolic pulmonary arterial pressure (SPAP) and left ventricular (LV) function, and (3) to establish the corresponding reference intervals (Study 2). For both studies, RV variables included tricuspid annular plane systolic excursion (TAPSE), right fractional area change (RFAC), STE longitudinal systolic strain (StS) of the RV free wall (RVFW) and of the entire RV (i.e., global RV StS), STE longitudinal systolic RVFW strain rate (SRS), and the diastolic early:late strain rate ratio. All but one within- and between-day coefficients of variation (13/14) were < 15%, the lowest being observed for TAPSE (3.6–9.8%), global RV StS (3.8–9.9%), and RVFW StS (3.7–7.3%). SPAP was weakly and negatively correlated with the TAPSE:body weight ratio (r_s = −0.26, p = 0.01) and RVFW SRS (r_s = −0.23, p < 0.05). Reference intervals (lower and upper limits with 90% confidence intervals) were provided for all variables. STE provides a non-invasive evaluation of RV function that may be used for clinical investigations in canine cardiology.

Systemic effects of a high saturated fat diet in grizzly bears (Ursus arctos horribilis)

Food sources for North America’s grizzly bear (Ursus arctos horribilis Ord, 1815) population have changed as habitats have fragmented, altering available resources and putting bears in contact with unnatural foods. Bears have evolved mechanisms to tolerate obesity, and do not develop adverse health consequences despite storing massive amounts of body fat. Captive adult grizzly bears were used to determine the effects of dietary fat on health. Group 1 was fed a diet high in polyunsaturated fatty acids (PUFA) wherein 9.5% of available calories came from saturated fatty acids (SFA). Group 2 was fed a diet wherein 28.8% of calories came from SFA. Plasma fatty acids, serum lipid profiles, insulin, inflammatory markers, systolic and diastolic blood pressure, and cardiac function parameters were measured. Serum lipids, SFA, and insulin did not differ between the two groups, although omega-3 fatty acids differed. Bears eating the SFA diet had significantly higher circulating adiponectin, interleukin-7 and interleukin-15, and tumor necrosis factor-alpha. Mild, asymptomatic systolic and diastolic dysfunctions were detected by strain echocardiography in the SFA group. The SFA diet group exhibited higher diastolic arterial pressures. Even though mild metabolic derangements were observed, grizzly bears were remarkably resistant to metabolic effects of diets high in SFA.

Cardiac and Metabolic Variables in Obese Dogs

Background

The etiology of obesity‐related cardiac dysfunction (ORCD) is linked to metabolic syndrome in people. Studies have indicated that obese dogs have components of metabolic syndrome, warranting evaluation for ORCD in obese dogs.

Objectives

To evaluate cardiac structure and function and metabolic variables in obese dogs compared to ideal weight dogs.

Animals

Forty‐six healthy, small‐breed (<25 pounds), obese dogs (n = 29) compared to ideal weight dogs (n = 17).

Methods

A cross‐sectional study of cardiac structure and function by standard and strain echocardiographic measurements and quantification of serum metabolic variables (insulin:glucose ratios, lipid analysis, adiponectin, inflammatory markers).

Results

Compared to the ideal weight controls, obese dogs had cardiac changes characterized by an increased interventricular septal width in diastole to left ventricular internal dimension in diastole ratio, decreased ratios of peak early to peak late left ventricular inflow velocities, and ratios of peak early to peak late mitral annular tissue velocities, and increased fractional shortening and ejection fraction percentages. The left ventricular posterior wall width in diastole to left ventricular internal dimension in diastole ratios were not significantly different between groups. Systolic blood pressure was not significantly different between groups. Obese dogs had metabolic derangements characterized by increased insulin:glucose ratios, dyslipidemias with increased cholesterol, triglyceride, and high‐density lipoprotein concentrations, decreased adiponectin concentrations, and increased concentrations of interleukin 8 and keratinocyte‐derived chemokine‐like inflammatory cytokines.

Conclusions and Clinical Importance

Compared to ideal weight controls, obese dogs have alterations in cardiac structure and function as well as insulin resistance, dyslipidemia, hypoadiponectinemia, and increased concentrations of inflammatory markers. These findings warrant additional studies to investigate inflammation, dyslipidemia, and possibly systemic hypertension as potential contributing factors for altered cardiac function.

Echocardiographic evaluation of left ventricular diastolic function in cats: Hemodynamic determinants and pattern recognition

Left ventricular (LV) diastolic dysfunction is highly prevalent in cats and is a functional hallmark of feline cardiomyopathy. The majority of cats with hypertrophic, restrictive, and dilated cardiomyopathy have echocardiographic evidence of abnormal LV filling, even during the occult (preclinical) phase. Moderate and severe diastolic dysfunction is an indicator of advanced myocardial disease, is associated with clinical signs including exercise intolerance and congestive heart failure, affects outcome, and influences therapeutic decisions. Therefore, identification and quantification of LV diastolic dysfunction are clinically important. Surrogate measures of diastolic function determined by transthoracic two-dimensional, M-mode, and Doppler echocardiographic (DE) methods have been used widely for such purpose. Major functional characteristics of LV diastole, including global function, relaxation and untwist, chamber compliance, filling volume, and the resultant filling pressures can be semi-quantified by echocardiographic methods, and variables retrieved from transmitral flow, pulmonary vein flow, and tissue Doppler recordings are most frequently used. Although there is still a critical lack of well-designed studies in the field, knowledge has steadily accumulated over the past 20 years, reference ranges of diastolic echocardiographic variables have been determined, epidemiological studies have been conducted, and new treatments of diastolic dysfunction in cats have been evaluated. This report will give the reader a summary of the current status in the field of feline diastology with focus on the noninvasive diagnostic methods and interpretation of echocardiographic surrogate measures of LV diastolic function. Lastly, a grading system using a composite of left atrial size and various DE variables potentially useful in the functional classification of LV diastole in cats is introduced.

Assessment of cardiac troponin I (cTnI) and tissue velocity imaging (TVI) in 14 dogs with malignant lymphoma undergoing chemotherapy treatment with doxorubicin

Doxorubicin has been shown to be cardiotoxic at high doses but is an efficacious chemotherapeutic agent in the treatment of canine lymphoma. Echocardiographic measurements and serum ultrasensitive cardiac troponin I (cTnI) levels were obtained before and after doxorubicin administration in 14 dogs diagnosed with lymphoma. The aim of this prospective study was to evaluate changes in cTnI concentrations and tissue velocity imaging (TVI) values in dogs with lymphoma undergoing chemotherapy with doxorubicin. A total of 182 cTnI and 1017 TVI measurements were performed. Standard echocardiographic parameters, tissue Doppler indices and cTnI concentrations did not differ at any time point within a 12-week cyclic combination protocol. In conclusion, the use of doxorubicin at standard doses in the treatment of canine lymphoma may not be associated with significant myocardial damage.

Usefulness of conventional and tissue Doppler echocardiography to predict congestive heart failure in dogs with myxomatous mitral valve disease

Background

Systolic and diastolic functions have been evaluated to predict outcome in congestive heart failure (CHF). Recently, tissue Doppler imaging (TDI) has become useful for the estimation of myocardial function in cardiac diseases of humans and animals.

Objective

This study was designed to assess whether myocardial function as assessed by TDI is associated with the occurrence of CHF in dogs with myxomatous mitral valve disease (MMVD) and whether additional information is gained over conventional Doppler variables.

Animals

Forty‐one privately owned dogs (15 healthy dogs and 26 dogs with MMVD) were included. Dogs with MMVD were divided into non‐CHF (n = 10) and CHF groups (n = 16).

Methods

Conventional echocardiographic examinations were performed. In addition, TDI‐derived variables, including radial and longitudinal velocities, strain, and strain rate were assessed.

Results

Several (12 of 47, 26%) conventional and tissue Doppler echocardiography variables were significant predictors of CHF in a univariate analysis (P < .05). However, TDI‐derived E/E_{m sept} was the only load‐independent significant predictor of CHF (P < .05) after multivariate logistic regression analysis. The E/E_{m sept} cut‐off value of >18.7 had a sensitivity of 56% and specificity of 90% in predicting CHF in dogs with MMVD.

Conclusions and Clinical Importance

The combination of TDI of the mitral annulus and mitral inflow velocity provided better estimates of diastolic dysfunction in dogs with MMVD and CHF. Additional study is warranted to assess TDI‐derived E/E_{m sept}, an index of diastolic function that could contribute to the management of dogs with MMVD and CHF.

Left ventricular radial colour and longitudinal pulsed-wave tissue Doppler echocardiography in 39 healthy domestic pet rabbits

This paper reports radial colour and longitudinal mitral annulus pulsed-wave tissue Doppler findings in a large cohort of healthy, adult pet rabbits. Thirty-nine rabbits (22 Dwarf Lops, 14 French Lops and three Alaskans) underwent conscious echocardiography. The median age of the rabbits was 22 months and the median weight was 2.8 kg (Dwarf Lop 2.4 kg/French Lop 6.0 kg). Adequate radial colour and longitudinal pulsed-wave tissue Doppler traces were obtained in 100% and 85% of cases, respectively. Most systolic tissue Doppler parameters were significantly higher in French Lops than in Dwarf Lops. Separation of mitral inflow diastolic waves was present in 40% of cases using conventional spectral Doppler and in >60% of cases using pulsed-wave tissue Doppler which could be beneficial when evaluating diastolic function in rabbits. This study can be used as a reference for normal echocardiographic tissue Doppler values for adult rabbits undergoing conscious echocardiography in clinical practice.

Left ventricular strain distribution in healthy dogs and in dogs with tachycardia-induced dilated cardiomyopathy

Background

Recently, left ventricular (LV) strain distribution pattern has been assessed in several cardiac disease states. Tachycardia-induced cardiomyopathy (TIC) is an animal model of non-ischemic cardiomyopathy well characterized in terms of global LV dysfunction but with poor understanding of regional variability in LV function. We hypothesized that TIC induces specific changes in LV strain distribution pattern.

Methods

Twenty five adult mongrel conscious dogs were trained to lie down calmly for echocardiography. In seven selected dogs, we implanted pacing system for TIC induction under general anesthesia. We measured LV geometry and function, strains, and torsion before and after the development of TIC in awake non-sedated state.

Results

In 25 healthy dogs, all three types of normal strain significantly increased from base to apex (p <0.05), while a definite and recognizable twist could be measured due to presence of shear strain. In 7 dogs with TIC, marked changes in LV mechanics occurred throughout the cardiac cycle, resulting in decrease of strain (p <0.001), twist (p <0.05), and negative peak twist rate (p <0.05). Interestingly, the relative decrease of strain due to TIC was more pronounced in the apex (p < 0.001), with the radial strain decreasing the most (p < 0.05).

Conclusion

TIC is accompanied by decreased systolic LV strain and twist deformation, as well as loss of early diastolic recoil. In addition, the decrease of strain was more profound in the apex. This “reverse” distribution of LV strain may help us understand LV dysfunction in the presence of nonischemic etiology.

Evaluation of changes in left ventricular myocardial function observed in canine myocardial dysfunction model using a two-dimensional tissue tracking technique

This study was conducted to assess the ability of two-dimensional tissue tracking (2DTT) to evaluate changes in left ventricular (LV) myocardial function associated with sustained high electrical pacing. Pacemakers were implanted at the right ventricular (RV) apex of five female Beagles, and sustained high electrical pacing of 250 beats per minute (bpm) was performed for three consecutive weeks. Conventional echocardiography and 2DTT were performed at baseline, and at every week for three weeks with pacing. The baseline parameters were then compared to those of weeks 1, 2, and 3. Three weeks of pacing resulted in significant reduction of radial and circumferential global strains (p < 0.001). Regional analysis revealed reduction of segmental strains in both radial and circumferential directions, as well as increased dyssynchrony after three weeks of pacing in the radial direction (p = 0.0007). The results of this study revealed the ability of 2DTT to measure radial and circumferential strains in dogs with sustained high-electrical pacing, and allowed assessment of global and regional myocardial function and the degree of dyssynchrony.

Within-day and between-day variability of transthoracic anatomic M-mode echocardiography in the awake bottlenose dolphin (Tursiops truncatus)

The use of transthoracic echocardiography in dolphins has been limited so far owing to technical and anatomical specificities. Anatomic M-mode (AMM) is a postprocessing echocardiographic technique generating M-mode studies from two-dimensional (2D) cineloops independently of the ultrasound beam orientation. The aim of the present study was to determine the within-day (repeatability) and between-day (reproducibility) variability of AMM echocardiography in awake healthy bottlenose dolphins (BN, Tursiops truncatus). Four adult BN trained to lie in left recumbency at the water surface were involved in the protocol. A total of 96 echocardiographic examinations were performed on 4 different days by a trained observer examining each BN 6 times per day. Video clips of 2D left parasternal long-axis views showing the left ventricle (LV) ventrally and the aortic root dorsally were recorded at each examination and analyzed for AMM measurements in a random order. A general linear model was used to determine the within-day and between-day coefficients of variation (CV). All examinations were interpretable allowing calculation of 10 AMM variables (i.e., end-diastolic and end-systolic ventral and dorsal LV myocardial wall thicknesses as well as LV and aortic diameters, mean aortic diameter, and LV shortening fraction). Most within- and between-day CV values (18/20) were <15%, the lowest being observed for the end-diastolic LV diameter (1.6%). In conclusion, AMM provides a simple non-invasive evaluation of heart morphology and function in the awake BN with good repeatability and reproducibility of the measurements. Further studies are required to determine the corresponding reference intervals.

Echocardiographic assessment of canine degenerative mitral valve disease

Degenerative mitral valve disease (MVD), the most common acquired heart disease in small-sized dogs, is characterized by valvular degeneration resulting in systolic mitral valve regurgitation (MR). Worsening of MR leads to several combined complications including cardiac remodeling, increased left ventricular filling pressure, pulmonary arterial hypertension, and myocardial dysfunction. Conventional two-dimensional, M-mode, and Doppler examination plays a critical role in the initial and longitudinal assessment of dogs affected by MVD, providing information on mitral valve anatomy, MR severity, left ventricular (LV) size and function, as well as cardiac and vascular pressures. Several standard echocardiographic variables have been shown to be related to clinical outcome. Some of these markers (e.g., left atrium to aorta ratio, regurgitation fraction, pulmonary arterial pressure) may also help in identifying asymptomatic MVD dogs at higher risk of early decompensation, which remains a major issue in practice. However, both afterload and preload are altered during the disease course. This represents a limitation of conventional techniques to accurately assess myocardial function, as most corresponding variables are load-dependent. Recent ultrasound techniques including tissue Doppler imaging, strain and strain rate imaging, and speckle tracking echocardiography, provide new parameters to assess regional and global myocardial performance (e.g., myocardial velocities and gradients, deformation and rate of deformation, and mechanical synchrony). As illustration, the authors present new data obtained from a population of 91 dogs (74 MVD dogs, 17 age-matched controls) using strain imaging, and showing a significant longitudinal systolic alteration at the latest MVD heart failure stage.

Color-coded longitudinal interventricular septal tissue velocity imaging, strain and strain rate in healthy Doberman Pinschers

OBJECTIVE

To determine reference values for septal longitudinal tissue Doppler imaging (TDI) in Doberman Pinschers.

BACKGROUND

TDI includes several new techniques, such as tissue velocity imaging (TVI), strain, and strain rate that might be used to detect early myocardial dysfunction. However, before these techniques can be used, breed specific reference ranges need to be established.

ANIMALS, MATERIALS AND METHODS

One-hundred healthy Doberman Pinschers ≥ 4 years of age were prospectively evaluated using electrocardiography, Holter recording, and echocardiography. Systolic, early and late diastolic parameters of septal longitudinal color-coded TVI, strain, and strain rate were analyzed in three myocardial segments (basal, middle, and apical).

RESULTS

TDI was feasible in all Doberman Pinschers. Reference values were established for every myocardial segment. There was a significant velocity gradient from the basal to the apical segment for all TVI parameters. No differences between the three segments were found for systolic strain and strain rate. Several diastolic strain rate values were significantly different between myocardial segments. Influence of age, weight, and gender was not clinically relevant.

CONCLUSIONS

This study provides reference values for TVI, strain, and strain rate in Doberman Pinschers. The parameters established here can be used for a supportive diagnostic approach.

Advanced techniques in echocardiography in small animals

Transthoracic echocardiography has become a major imaging tool for the diagnosis and management of canine and feline cardiovascular diseases. During the last decade, more recent advances in ultrasound technology with the introduction of newer imaging modalities, such as tissue Doppler imaging, strain and strain rate imaging, and 2-dimensional speckle tracking echocardiography, have provided new parameters to assess myocardial performance, including regional myocardial velocities and deformation, ventricular twist, and mechanical synchrony. An outline of these 4 recent ultrasound techniques, their impact on the understanding of right and left ventricular function in small animals, and their application in research and clinical settings are given in this article.

Comparison of left ventricular contraction profiles among small, medium, and large dogs by use of two-dimensional speckle-tracking echocardiography

OBJECTIVE

To assess differences in left ventricular contractile indices among dogs of 3 body sizes via 2-D speckle-tracking echocardiography (STE) and to determine body weight-independent systolic variables.

ANIMALS

37 clinically normal adult dogs.

PROCEDURES

Dogs were allocated into 3 groups on the basis of body weight: small (<7kg), medium (7 to 20kg), and large (>20kg). Right parasternal short-axis echocardiographic views were acquired to measure conventional M-mode variables (left ventricular internal diameter at end diastole, left ventricular internal diameter at end systole, and fractional shortening [FS]) and STE indices (peak systolic strain, peak systolic strain rate, synchrony time index [STI], peak systolic apical rotation, peak systolic basal rotation, peak apical twisting rate, and peak systolic torsion). Values were compared among the 3 groups.

RESULTS

STE indices, except for peak systolic radial strain (SRad), peak systolic basal rotation, and STI, were significantly decreased in large dogs, compared with values for small and medium dogs. No significant difference was detected in stroke index, peak systolic SRad, and peak systolic basal rotation among the 3 groups. The STI in large dogs was significantly increased, compared with that of medium dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results revealed that decreased systolic indices in large dogs should not be interpreted as signs of decreased systolic function. Increased STI in large dogs may contribute to decreased FS. Because peak systolic SRad was not affected by body weight, peak systolic SRad might be a better variable than FS for assessing systolic function.

Doppler-derived deformation imaging in unsedated healthy adult dogs

OBJECTIVES

To evaluate feasibility, repeatability and reproducibility (R&R) of Doppler-derived deformation imaging (DI) in healthy adult dogs.

ANIMALS, MATERIALS AND METHODS

Forty-nine dogs underwent physical examination, ECG, blood pressure measurement and echocardiography. Doppler-derived DI parameters obtained from six selected Regions of Interest (ROI) within the left ventricle (LV) were: strain (S), systolic strain rate (SSR), strain rate E wave (SRE), and strain rate A wave (SRA). The averages of the six ROIs were calculated and labeled avS, avSSR, avSRE, and avSRA. Randomly selected dogs underwent two echocardiographic studies to evaluate intraoperator (n=14) and interoperator (n=17) variability.

RESULTS

DI data were obtained in 87.2% of dogs and 77.2% of ROIs. Compared to controls, avSSR was significantly reduced in Doberman Pinchers (DP) and it was increased in dogs < 30 kg, compared to dogs > 30 kg. The intraoperator Coefficient of Variability (CV) for some ROIs was greater than 15% but for averaged measurements it was < or = 5.0%. Interoperator CV varied widely but were all < 15% for avSSR, avS, and avSRA.

CONCLUSIONS

The CV for Doppler-derived DI varied widely. Averaging values from multiple ROIs improved R&R. DI may help elucidate differences in LV mechanics between canine breeds.