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  • Author or Editor: Yasutomo Hori x
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Abstract

Objective—To evaluate the effect of changes in hemodynamics on the myocardial performance index (MPI) in cats.

Animals—6 mixed-breed cats.

Procedures—Cats were anesthetized by administration of thiopental sodium; anesthesia was maintained by administration of isoflurane. Systolic arterial pressure and central venous pressure were measured by use of catheters, and heart rate was controlled by right atrial pacing. Afterload was increased by balloon occlusion of the descending aorta, and preload was increased by IV infusion of lactated Ringer's solution at a rate of 40 mL/kg/h. Echocardiography was performed for each condition.

Results—Atrial pacing significantly increased heart rate. The MPI did not change with heart rate. Arterial pressure and MPI increased significantly during aortic occlusion. The IV infusion increased fractional shortening but did not change the MPI. Multiple regression analysis revealed that the MPI was not affected by heart rate, systolic arterial pressure, central venous pressure, fractional shortening, or velocity of the E wave.

Conclusions and Clinical Relevance—The MPI can be used to assess cardiac function in healthy cats. The MPI is independent of heart rate and systolic arterial pressure but is sensitive to changes in afterload.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To investigate whether lung ultrasonography (LUS) performed around the heart, where the lungs are in contact with the pericardium (ie, pericardial LUS), could be used for the diagnosis of cardiogenic pulmonary edema (CPE) in dogs with degenerative mitral valve disease (DMVD).

ANIMALS

15 control dogs with healthy hearts and 26 dogs with DMVD.

PROCEDURES

In a prospective multicenter study design, dogs with DMVD were assigned to 2 groups: those with CPE (n = 11) and those without CPE (15). Thoracic radiography, echocardiography, and pericardial LUS were performed for all dogs. For pericardial LUS, the left ventricular short-axis view was obtained with a sector probe (dog positioned in right parasternal recumbency) and the number of B lines was recorded. Accuracy of pericardial LUS for the diagnosis of CPE was calculated, with thoracic radiography used as the reference standard.

RESULTS

On thoracic radiography, all dogs with CPE had a diffuse distribution of interstitial to alveolar pulmonary infiltrates. On pericardial LUS, most control dogs (14/15) and dogs with DMVD but no CPE (13/15) had ≤ 2 B lines, whereas all dogs with DMVD and CPE had ≥ 3 B lines. The presence of ≥ 4 B lines had high sensitivity (91%; 95% confidence interval, 62% to 98%) and excellent specificity (100%; 95% confidence interval, 89% to 100%) for the diagnosis of CPE, and the area under the receiver operating characteristic curve was 0.99.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that identification of ≥ 4 B lines extending from the epicardium of the left ventricle into the lung field on pericardial LUS may be useful in the diagnosis of CPE in dogs with DMVD. Additional research is needed to determine whether pericardial LUS allows differentiation between CPE and pneumonia.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the relationship between the myocardial performance index (MPI) determined by use of pulsed Doppler (PD) echocardiography and tissue Doppler imaging (TDI) in the response to volume overload–related changes in left ventricle (LV) performance.

Animals—7 male Beagles.

Procedures—Dogs were anesthetized and intubated. A 6-F fluid-filled catheter was placed in the LV to measure LV peak systolic (LVPs) and LV end-diastolic (LVED) pressures. Preload was increased by IV infusion of lactated Ringer's solution (rate of 200 mL/kg/h for 60 minutes) into a cephalic vein. Transmitral flow velocities and aortic outflow were measured, and TDI velocities were obtained from the 4-chamber view.

Results—Acute volume overload induced a significant increase in heart rate, LVPs pressure, and LVED pressure, compared with baseline values. A significant decrease in the PD-MPI and TDI-MPI values and a significant correlation (r = 0.70) between PD-MPI and TDI-MPI were detected. The PD-derived A-wave velocity, ejection time, and isovolumic relaxation time (IRT) and the TDI-derived IRT, MPI, and ratio of the velocity of the E wave to the velocity of the ventricular portion of the E wave during early diastole had equal ability to predict LVED pressure (r 2 = 0.63).

Conclusions and Clinical Relevance—The TDI-MPI was closely correlated with LV filling pressure and may be helpful in evaluating global cardiac function in dogs.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate tissue Doppler imaging (TDI) of the left ventricular (LV) free wall (FW) and ventricular septum (VS) as an indicator of LV systolic function in dogs.

Animals—7 healthy Beagles.

Procedures—Doses of dobutamine (5 and 10 μg/kg/min) and esmolol (50 and 100 μg/kg/min) were infused into the LV of each dog. With each dose, heart rate; myocardial performance index (MPI); transmitral inflow and ejection time (determined via pulsed-wave Doppler [PWD] echocardiography); and FW and VS velocities of the mitral valve annulus (determined via TDI during systole [S’], early diastole [E’], and late diastole [A’]) were assessed.

Results—With each dose, dobutamine significantly increased heart rate and the first derivatives of LV pressure (+dP/dt and –dP/dt), whereas esmolol significantly decreased the +dP/dt and –dP/dt values, compared with baseline. Esmolol (100 μg/kg/min) significantly decreased the VS-TDI–derived S’ velocity and FW-TDI–derived E’ velocity; dobutamine significantly increased transmitral inflow and TDI velocities. Regression coefficient between VS-TDI–derived S’ velocity and +dP/dt was higher than that between FW-TDI–derived S’ velocity and +dP/dt. Compared with baseline, the PWD- and VS-TDI–derived MPI were significantly decreased by dobutamine and significantly increased by esmolol at each dose. Values of FW-TDI–derived MPI were higher than values derived via the other techniques. Correlation between +dP/dt and VS-TDI–derived MPI was greater than that between +dP/dt and FW-TDI– or PWD-derived MPI.

Conclusions and Clinical Relevance—In healthy dogs, the VS-TDI–derived S’ velocity and MPI appear to be reliable assessments for evaluating LV systolic function.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the relationship between preload and tricuspid valve annulus–derived tissue Doppler imaging (TDI) as an index of right ventricular (RV) filling in dogs.

Animals—7 Beagles.

Procedures—Peak systolic RV pressure and RV end-diastolic pressure (RVEDP) were measured in anesthetized dogs. Pulsed Doppler was used to measure tricuspid valve inflow and pulmonary valve outflow velocities. The TDI velocities were measured at the lateral corner of the tricuspid valve annulus. Lactated Ringer's solution was infused at 200 mL/kg/h for 60 minutes via the cephalic vein.

Results—IV infusion significantly increased heart rate, RV pressure, and RVEDP. Early diastolic flow (E-wave) and ejection time significantly increased. The myocardial performance index (MPI) significantly decreased. Intravenous infusion significantly increased the ratio of the E'-wave (peak myocardial velocity during early diastole) to the A'-wave (peak myocardial velocity during late diastole; E':A' ratio) and myocardial velocity during systole (S'), early diastole (E'), and late diastole (A'). The TDI-isovolumic relaxation time and TDI-MPI decreased significantly. The RVEDP was correlated with late diastolic flow (A-wave), ratio of the E-wave to the A-wave (E:A ratio), E'-wave, A'-wave, S'-wave (peak myocardial velocity during systole), TDI-isovolumic relaxation time, TDI-MPI, and ratio of the E-wave to the E'-wave (E: E' ratio). The A-wave and E:A ratio and TDI-derived isovolumic relaxation time, S' duration, and E'-wave could predict the RVEDP.

Conclusions and Clinical Relevance—The TDI velocities were affected by RV filling pressure in healthy dogs, whereas other TDI profiles, such as MPI and E':A' ratio, were independent of acute filling abnormalities.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the relationship between velocities of pulmonary venous flow (PVF) and plasma concentrations of atrial natriuretic peptide (ANP) in healthy dogs.

Animals—7 healthy Beagles.

Procedures—Dogs were anesthetized, intubated, and positioned in left lateral recumbency. Lactated Ringer's solution was infused (200 mL/kg/h) for 60 minutes via a cephalic vein. Transmitral flow and PVF velocities were measured echocardiographically by use of the apical 4-chamber view. Pulmonary capillary wedge pressure (PCWP) and ANP concentrations were determined.

Results—IV infusion significantly increased heart rate and PCWP. Similarly, the ANP concentration significantly increased from baseline (before infusion of lactated Ringer's solution) values. Transmitral flow velocities were significantly increased, although the ratio of velocity of the flow during early ventricular diastole (E wave) to velocity of the atrial flow (A wave; E:A ratio) was unchanged. Regarding the PVF velocities, forward flow during ventricular systole (S wave) and retrograde flow during atrial contraction were significantly increased, whereas velocity of the forward flow during ventricular diastole (D wave) was unchanged. Ratio of the velocity of the S wave to velocity of the D wave was increased significantly, and this ratio was significantly correlated with PCWP or ANP concentration. However, the E:A ratio was not correlated with PCWP or ANP concentration.

Conclusions and Clinical Relevance—PVF velocities were strongly correlated with PCWP and plasma ANP concentration in clinically normal dogs. Therefore, PVF velocities may serve as a sensitive indicator and provide additional information for monitoring acute preloading conditions and estimating atrial filling abnormalities in dogs.

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.

Restricted access
in Journal of the American Veterinary Medical Association

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 investigate the diuretic effects, tolerability, and adverse effects of furosemide and torsemide after short- and long-term administration in healthy dogs.

Animals—8 mixed-breed dogs.

Procedures—In a crossover study, furosemide (2 mg/kg), torsemide (0.2 mg/kg), or placebo (bifidobacterium [1 mg/kg]) was administered orally to each dog every 12 hours for 14 days. Blood and urine samples were collected before the study (baseline data) and at intervals on the 1st (short-term administration) and 14th day (long-term administration) of treatment for assessment of urine volume and specific gravity and selected clinicopathologic variables including BUN, creatinine, and aldosterone concentrations, and creatinine clearance.

Results—Compared with the baseline value, short-term administration of furosemide or torsemide immediately increased urine volume significantly; after long-term administration of either drug, urine specific gravity decreased significantly. Compared with the effect of placebo, the 24-hour urine volume was significantly increased after short-term administration of furosemide or torsemide. In addition, it was significantly increased after long-term administration of torsemide, compared with that of short-term administration. Long-term administration of furosemide or torsemide increased the BUN and plasma creatinine con-centrations, compared with the baseline value. Compared with the baseline value, plasma aldosterone concentration was significantly increased after long-term administration of either drug and was significantly higher after torsemide treatment than after furosemide treatment.

Conclusions and Clinical Relevance—In dogs, diuretic resistance developed after 14 days of furosemide, but not torsemide, administration; however, both loop diuretics were associated with increased BUN and plasma creatinine concentrations, compared with values before treatment.

Full access
in American Journal of Veterinary Research

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