The Effect of Pimobendan on Left Atrial Pressure in Dogs with Mitral Valve Regurgitation

Abstract

Background: The effects of pimobendan on left atrial pressure (LAP) in dogs with mitral valve disease (MR) have not been documented in a quantitative manner.Objective: The objective was to document and study the short-term effects of pimobendan on LAP and echocardiographic parameters in MR dogs.Animals: Eight healthy Beagle dogs weighing 10.0-14.7 kg (3 males and 5 females; aged 2 years) were used. Methods: Experimental, cross-over, and interventional study. Dogs with surgically induced MR received pimobendan at either 0.25 mg/kg or 0.50 mg/kg PO q12h for 7 days and then, after a 7-day wash-out period, the other dosage. LAP was measured for 30 minutes at baseline and again on days 1, 2, 4, and 7 of pimobendan administration.Results: Mean LAP was significantly decreased after the administration of 0.25 mg/kg (15.81 ± 5.44 mmHg to 12.67 ± 5.71 mmHg, P < .001) and 0.50 mg/kg (15.76 ± 5.45 mmHg to 10.77 ± 5.23 mmHg, P < .001). Also, the 0.50 mg/ kg group led to a significantly lower LAP (P < .01) compared with the 0.25 mg/kg group. Significant reduction was seen for the first time 4 days after the administration of 0.25 mg/kg and a day after the administration of 0.50 mg/kg.Conclusions and Clinical Importance: Pimobendan decreased LAP in a dose-dependent manner in dogs with acute MR caused by experimental chordal rupture. This study did not evaluate adverse effects of high-dose pimobendan, and additional studies in clinical patients are warranted.

Short‐Term Hemodynamic and Neuroendocrine Effects of Pimobendan and Benazapril in Dogs with Myxomatous Mitral Valve Disease and Congestive Heart Failure

“…To do that in the face of reduced HR and no increase in total SV (=reduced total CO), RV must have decreased, which is also indicated by the smaller LA (Table ) . Reduced cardiac size and LA pressure with maintained forward SV and forward CO has previously been described in dogs with mild MR treated with pimobendan . Lower HR with maintained forward CO indicates that the forward SV increased, and the only explanation of this, in the absence of increased ventricular total SV, is again a reduced RV.…”

ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs

“…(Class I, LOE: expert opinion; humane considerations apply) Pimobendan, 0.25‐0.3 mg/kg administered PO q12h. Although the clinical trial evidence supporting the chronic use of pimobendan in the management of Stage C heart failure from MMVD is stronger than for the acute presentation, the recommendation to use pimobendan in acute heart failure treatment is strongly supported by hemodynamic and experimental evidence as well as the anecdotal experience of the panelists. In many countries outside of the United States, pimobendan for IV administration is available.…”

Effects of a Sustained‐Release Form of Isosorbide Dinitrate on Left Atrial Pressure in Dogs with Experimentally Induced Mitral Valve Regurgitation

“…In our previous reports, we evaluated the effects of ACE inhibitors, furosemide, and pimobendan on the dogs with experimentally induced MR . This study and the previous studies indicate that the most effective method to reduce LAP is decreasing the circulating blood volume by diuresis.…”