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  • Author or Editor: Myrielle Mathieu x
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Abstract

Objective—To assess the influence of age on pulmonary hemodynamics and hemorheological properties in healthy dogs.

Animals—14 healthy Beagles.

Procedures—Dogs were placed in 2 age groups as follows: young dogs (≤ 5 years old; n = 8) and old dogs (≥ 8 years old; 6). Hematologic characteristics, plasma total protein and fibrinogen concentrations, and blood viscosity were measured. Systolic time intervals of pulmonary blood flow were recorded by pulsed-wave Doppler echocardiography. Early (E′) and late (A′) diastolic myocardial velocities, isovolumic contraction velocity, and systolic myocardial velocity of the free tricuspid annulus were recorded by pulsed-wave tissue Doppler imaging (TDI). Dogs were anesthetized and pulmonary arterial pressures (PAP) and cardiac output were recorded with a pediatric thermodilution Swan-Ganz catheter.

Results—Hemorheological measurements were not different between the 2 groups. Systolic, mean, and diastolic PAP were higher in old dogs, compared with values in young dogs; this difference was attributed to a high pulmonary vascular resistance and low arterial compliance in old dogs. Systolic time intervals of pulmonary blood flow stayed unchanged. The A′ wave of the free tricuspid annulus was increased in old, compared with that young dogs, and the E′:A′ ratio was decreased. Pulmonary vascular resistance was inversely correlated with compliance.

Conclusions and Clinical Relevance—The age of dogs should be taken into account when interpreting pulmonary hemodynamic results and TDI variables of right ventricular diastolic function.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the effects of preventive angiotensin converting enzyme inhibitor treatment with ramipril in dogs with progressively severe experimentally induced heart failure.

Animals—20 dogs.

Procedures—Dogs were randomly allocated to receive no treatment (control) or ramipril (0.125 mg/kg, PO, daily) for 7 weeks. Physical examination, repetitive catheterization of the right side of the heart, and echocardiography were performed before the study (day 0) and weekly for 7 weeks. Renal plasma flow (RPF) as determined by para-aminohippuric acid clearance and glomerular filtration rate (GFR) as determined by creatinine and iohexol clearances were measured on day 0 and at weeks 4 and 7.

Results—Overpacing induced a progressive increase in right atrial pressure (RAP) and pulmonary artery pressure, occluded (PAPO), with a decrease in systemic arterial pressure. There were progressive alterations of echocardiographic indices of diastolic and systolic ventricular function. The RPF and GFR decreased before cardiac output decreased, and filtration fraction increased. The logarithm of the urinary sodium–to–potassium concentration ratio (log10[Na+/K+]) decreased. Significant effects of ramipril included a delay in clinical signs of heart failure, a late decrease in RAP and PAPO, and increases in the sodium excretion fraction and log10(Na+/K+). There was a satisfactory agreement between the creatinine and iohexol clearance measurements.

Conclusions and Clinical Relevance—Results suggest that, in this rapid-evolving, dilated cardiomyopathy, activation of the renin-angiotensin system contributes to the pathophysiology of heart failure late in the disease and essentially by an activation of renal salt and water retention.

Full access
in American Journal of Veterinary Research