Search Results

You are looking at 11 - 16 of 16 items for

  • Author or Editor: Mark D. Kittleson x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objective—To quantify myocardial contrast enhancement (MCE) of the left ventricle (LV) by use of cardiac magnetic resonance imaging (CMRI) in healthy cats and cats with hypertrophic cardiomyopathy (HCM) and to compare MCE between the 2 groups.

Animals—10 healthy cats and 26 Maine Coon cats with moderate to severe HCM but without clinical evidence of congestive heart failure.

Procedure—Anesthetized cats underwent gradient echo CMRI examination. Short-axis images of the LV were acquired before and 7 minutes after IV administration of gadolinium dimeglumine. Regions of interest were manually traced in the quadrants of 5 mid-LV slices acquired at end systole, and the MCE percentage was calculated from summed weight-averaged data from all slices. Doppler tissue imaging echocardiography was performed to measure the early diastolic myocardial velocity (Em) as an index of diastolic function. Three-way repeated-measures ANOVA was used to determine differences in MCE between cats with HCM and healthy cats. Simple linear regression was used to assess whether MCE was correlated with LV mass, LV mass index (LVMI), or Em. A Student t test was used to compare the SDs of the postcontrast myocardial signal intensity between the 2 groups.

Results—There was no difference in MCE between cats with HCM and healthy cats. There was no correlation of MCE with LV mass, LVMI, or Em. There was no difference in heterogeneity of signal intensities of LV myocardium between the 2 groups.

Conclusions and Clinical Relevance—Contrastenhancement CMRI was not useful in detecting diffuse myocardial fibrosis in cats with HCM. (Am J Vet Res 2005;66:1891–1894)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine cardiopulmonary effects of incremental doses of dopamine and phenylephrine during isoflurane-induced hypotension in cats with hypertrophic cardiomyopathy (HCM).

Animals—6 adult cats with severe naturally occurring HCM.

Procedures—Each cat was anesthetized twice (once for dopamine treatment and once for phenylephrine treatment; treatment order was randomized). Hypotension was induced by increasing isoflurane concentration. Cardiopulmonary data, including measurement of plasma concentration of cardiac troponin I (cTnI), were obtained before anesthesia, 20 minutes after onset of hypotension, and 20 minutes after each incremental infusion of dopamine (2.5, 5, and 10 μg/kg/min) or phenylephrine (0.25, 0.5, and 1 μg/kg/min).

Results—Mean ± SD end-tidal isoflurane concentration for dopamine and phenylephrine was 2.44 ± 0.05% and 2.48 ± 0.04%, respectively. Cardiac index and tissue oxygen delivery were significantly increased after administration of dopamine, compared with results after administration of phenylephrine. Systemic vascular resistance index was significantly increased after administration of phenylephrine, compared with results after administration of dopamine. Oxygen consumption remained unchanged for both treatments. Systemic and pulmonary arterial blood pressures were increased after administration of both dopamine and phenylephrine. Acid-base status and blood lactate concentration did not change and were not different between treatments. The cTnI concentration increased during anesthesia and infusion of dopamine and phenylephrine but did not differ significantly between treatments.

Conclusions and Clinical Relevance—Dopamine and phenylephrine induced dose-dependent increases in systemic and pulmonary blood pressure, but only dopamine resulted in increased cardiac output. Hypotension and infusions of dopamine and phenylephrine caused significant increases in cTnI concentrations.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To assess Doppler tissue imaging (DTI) for evaluating left ventricular diastolic wall motion in healthy cats and cats with cardiomyopathy.

Animals

20 healthy cats, 9 cats with hypertrophic cardiomyopathy (HCM), and 9 cats with unclassified cardiomyopathy (UCM).

Procedure

A pulsed wave DTI sample gate was positioned at a subendocardial region of the left ventricular free wall in the short axis view and at the lateral mitral annulus in the apical 4-chamber view. Indices of diastolic wall motion were measured, including peak diastolic velocity (PDV), mean rate of acceleration and deceleration of the maximal diastolic waveform (MDWaccel and MDWdecel, respectively), and isovolumetric relaxation time (IVRT).

Results

The PDV of cats with HCM and 6 of 9 cats with UCM was significantly decreased, compared with that of healthy cats. In the 3 cats with UCM that had a PDV that was not different from healthy cats, MDWaccel and MDWdecel were greater, and IVRT was shorter than those of healthy cats. The IVRT in cats with HCM was longer than that of other cats.

Conclusions and Clinical Relevance

Indices of diastolic function in cats with HCM, and in many cats with UCM, differed from those of healthy cats and were similar to those reported in humans with HCM and restrictive cardiomyopathy, respectively. However, the hemodynamic abnormality was not the same for all cats with UCM; some cats with an enlarged left atrium and a normal left ventricle (ie, UCM) had abnormal left ventricular wall motion consistent with restrictive cardiomyopathy while others did not. (Am J Vet Res 1999;60:1478–1486)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the prevalence of heart murmurs in chinchillas (Chinchilla lanigera) and determine whether heart murmurs were associated with cardiac disease.

Design—Retrospective multi-institutional case series.

Animals—260 chinchillas.

Procedures—Medical records of all chinchilla patients evaluated at the Tufts University Foster Hospital for Small Animals between 2001 and 2009, the University of California-Davis William R. Pritchard Veterinary Medical Teaching Hospital between 1996 and 2009, and the University of Wisconsin Veterinary Medical Teaching Hospital between 1998 and 2009 were reviewed.

Results—Prevalence of heart murmurs was 23% (59/260). Of 15 chinchillas with heart murmurs that underwent echocardiography, 8 had echocardiographic abnormalities, including dynamic right ventricular outflow tract obstruction, mitral regurgitation, hypertrophy of the left ventricle, tricuspid regurgitation, and hypovolemia. Echocardiographic abnormalities were approximately 29 times as likely (OR, 28.7) to be present in chinchillas with a murmur of grade 3 or higher than in chinchillas without a murmur.

Conclusions and Clinical Relevance—Results suggested that heart murmurs are common in chinchillas and that chinchillas with heart murmurs often have echocardiographic abnormalities, with valvular disease being the most common. On the basis of these results, we believe that echocardiography should be recommended for chinchillas with heart murmurs, especially older chinchillas with murmurs of grade 3 or higher. Further prospective studies are needed to accurately evaluate the prevalence of cardiac disease in chinchillas with heart murmurs.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate microbiologic findings in dogs with infective endocarditis (IE) and determine whether there were differences in clinical features of disease caused by different groups of infective agents.

Design—Retrospective case series.

Animals—71 dogs with suspected or definite IE.

Procedures—Medical records were reviewed for results of bacterial culture and susceptibility testing, serologic assays for vector-borne disease, and PCR testing on vegetative growths. Cases were grouped by causative organism and relationships among infectious agent group, and various hematologic, biochemical, and clinical variables were determined. Survival analyses were used to determine associations between infecting organisms and outcome.

Results—Causative bacteria were identified in 41 of 71 (58%) dogs. Gram-positive cocci were the causative agents in most (21/41; 51%) infections, with Streptococcus canis associated with 24% of infections. Gramnegative organisms were detected in 9 of the 41 (22%) dogs. Infection with Bartonella spp was detected in 6 of 31 (19%) dogs with negative results for microbial growth on blood culture. Aortic valve involvement and congestive heart failure were more frequent in dogs with endocarditis from Bartonella spp infection, and those dogs were more likely to be afebrile. Infection with Bartonella spp was negatively correlated with survival. Mitral valve involvement and polyarthritis were more frequent in dogs with streptococcal endocarditis.

Conclusions and Clinical Relevance—Streptococci were the most common cause of IE and were more likely to infect the mitral valve and be associated with polyarthritis. Dogs with IE secondary to Bartonella spp infection were often afebrile, more likely to develop congestive heart failure, rarely had mitral valve involvement, and had shorter survival times.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine signalment, clinical signs, diagnostic findings, treatment, and outcome for cats with atrial fibrillation (AF).

Design—Retrospective study.

Animals—50 cats.

Procedure—Medical records of cats that met criteria for a diagnosis of AF (ECG consisting of at least 2 leads, clear absence of P waves, supraventricular rhythm, and convincingly irregularly irregular rhythm) and had undergone echocardiography were reviewed.

Results—There were 41 males (37 castrated) and 9 females (7 spayed). Forty-one were of mixed breeding; 9 were purebred. Mean ± SD age was 10.2 ± 3.7 years. The most common chief complaints were dyspnea, aortic thromboembolism, and lethargy. In 11 cats, AF was an incidental finding. Mean ± SD ventricular rate was 223 ± 36 beats/min. The most common echocardiographic abnormalities were restrictive or unclassified cardiomyopathy (n = 19), concentric left ventricular hypertrophy (18), and dilated cardiomyopathy (6). Mean ± SD left atrial-to-aortic diameter ratio (n = 39) was 2.55 ± 0.80. The most common thoracic radiographic findings were cardiomegaly, pleural effusion, and pulmonary edema. Median survival time (n = 24) was 165 days (range, 0 to 1,095 days). Eight of 24 cats lived for ≥ 1 year after a diagnosis of AF was made.

Conclusions and Clinical Relevance—Results suggest that AF occurs primarily in older adult male cats with structural heart disease severe enough to lead to atrial enlargement. Atrial fibrillation in these cats was most commonly first detected when signs of decompensated cardiac disease were evident, but also was commonly identified as an incidental finding. (J Am Vet Med Assoc 2004;225:256–260)

Full access
in Journal of the American Veterinary Medical Association