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  • Author or Editor: Shigeki Yamano x
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Abstract

Objective—To clarify regulation of the renin-angiotensin (RA) system in cardiac tissues by measuring angiotensin-converting enzyme (ACE) and chymase activities in cats with pressure-overload cardiac hypertrophy.

Animals—13 adult cats.

Procedures—Pressure-overload cardiac hypertrophy was induced by coarctation of the base of the ascending aorta in 6 cats, and 7 cats served as untreated control animals. Cats were examined before and 3 months and 2 years after surgery. Two years after surgery, cardiac hypertrophy was confirmed by echocardiography, and the blood pressure gradient was measured at the site of constriction. Cats were euthanized, and ACE and chymase activities were measured in cardiac tissues.

Results—Mean ± SD pressure gradient across the aortic constriction was 63 ± 6 mm Hg. Chymase activity predominated (75% to 85%) in the RA system of the cardiac tissues of cats. Fibrosis in the wall of the left ventricle was detected in cats with hypertrophy, and fibrosis of the papillary muscle was particularly evident.

Conclusions and Clinical Relevance—Chronic pressure overload on the heart of cats can activate the RA system in cardiac tissues. A local increase in angiotensin II was one of the factors that sustained myocardial remodeling.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the relationship between myocardial performance index (MPI; also known as the Tei index) and cardiac function in anesthetized cats administered dobutamine.

Animals—6 adult cats.

Procedures—Cats were anesthetized by administration of propofol (6 mg/kg, IV), and anesthesia was maintained by administration of isoflurane. Heart rate and systolic arterial pressure (SAP) were monitored. Stroke volume, cardiac output, and aortic blood flow (ABF) were measured by use of transesophageal ultrasonography. Left ventricular fractional shortening (LVFS), mitral E-wave velocity-to-A-wave velocity (E:A) ratio, and ejection time were measured by use of transthoracic echocardiography. Dobutamine was administrated via a cephalic vein at rates of 2.5, 5.0, and 10 μg/kg/min.

Results—Heart rate, SAP, cardiac output, and ABF increased with dobutamine administration, whereas stroke volume significantly decreased. The LVFS significantly increased, and the E:A ratio significantly decreased. Total isovolumic time and the MPI significantly decreased. The MPI was negatively correlated (r = −0.63) with LVFS. Conversely, the MPI was positively correlated with the E:A ratio (r = 0.47), stroke volume (r = 0.66), and total isovolumic time (r = 0.95). However, the MPI was not significantly correlated with heart rate, SAP, cardiac output, or ABF.

Conclusion and Clinical Relevance—Analysis suggested that the MPI provides a sensitive clinical assessment of cardiac response to medication in cats, which may be similar to the usefulness of the MPI reported in humans.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether measurement of plasma atrial natriuretic peptide (ANP) concentration could be used to identify heart disease in dogs and to assess disease severity in affected dogs.

Design—Cross-sectional study.

Animals—37 healthy dogs and 78 dogs with heart disease.

Procedures—Dogs were divided into 5 groups on the basis of plasma ANP concentration: healthy, ANP-1 (< 50 pg/mL; n = 19), ANP-2 (50 to 100 pg/mL; 24), ANP-3 (101 to 200 pg/mL; 20), and ANP-4 (> 200 pg/mL; 15). All dogs underwent physical examination, echocardiography, thoracic radiography, and blood sampling before treatment.

Results—Compared with healthy dogs, dogs with increased plasma ANP concentration had significant concomitant increases in heart rate, cardiothoracic ratio, vertebral heart score, fractional shortening, ratio of left atrial-to-aortic root diameter, and mitral early diastolic flow (E wave) velocity and a significant decrease in relative wall thickness. Use of plasma ANP concentration > 25 pg/mL to identify dogs with heart disease (International Small Animal Cardiac Health Council class > I) had a sensitivity of 91.0% and specificity of 94.7%. Use of plasma ANP concentration > 100 pg/mL to identify dogs with International Small Animal Cardiac Health Council class IIIb heart disease had a sensitivity of 81.0% and specificity of 81.1 %.

Conclusions and Clinical Relevance—Results may provide reference values for plasma ANP concentration in dogs and suggest that plasma ANP concentration may help to distinguish dogs with cardiac disease from clinically normal dogs. Measurement of plasma ANP concentration may be a useful marker for predicting the severity of heart disease in dogs.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To evaluate and compare the clinical usefulness of plasma atrial natriuretic peptide (ANP) and cardiac troponin-I (cTnI) concentrations for assessment of disease severity in dogs with naturally occurring mitral valve disease (MVD).

ANIMALS

316 dogs with MVD and 40 healthy control dogs.

PROCEDURES

Each dog underwent a physical examination and echocardiographic and thoracic radiographic assessments. Blood samples were obtained and processed for measurement of plasma ANP and cTnI concentrations. Dogs with MVD were categorized into 3 groups (stages B1 [no clinical signs or evidence of cardiac enlargement], B2 [no clinical signs with evidence of cardiac enlargement], and C [history of congestive heart failure and pulmonary edema]) on the basis of American College of Veterinary Internal Medicine guidelines. Receiver operating characteristic curve analysis was used to evaluate the accuracy of plasma ANP and cTnI concentrations for assessment of MVD severity.

RESULTS

Plasma ANP and cTnI concentrations increased as disease severity increased. Median plasma ANP concentrations for all 3 MVD groups and median plasma cTnI concentrations for the stage B2 and C groups were significantly greater than the corresponding concentrations for the control group. Plasma ANP concentration, but not cTnI concentration, appeared to be useful for detection of dogs with subclinical (stages B1 and B2) MVD, whereas both concentrations appeared useful for detection of dogs with stage C MVD.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that plasma ANP and cTnI concentrations should not be used independently to diagnose MVD but can be used to assess MVD severity and supplement echocardiographic findings.

Full access
in Journal of the American Veterinary Medical Association