Effects of intravenous administration of pimobendan on hemodynamic indices and indices of left atrial longitudinal strain derived from speckle-tracking echocardiography in healthy dogs

Abstract

OBJECTIVE To determine the effects of IV administration of pimobendan on hemodynamic indices and indices of left atrial (LA) longitudinal strain by speckle-tracking echocardiography in healthy dogs. ANIMALS 6 healthy Beagles. PROCEDURES After the dogs were anesthetized, the right heart was catheterized and 2-D conventional and speckle-tracking echocardiography were performed before and after IV administration of 0.15 mg of pimobendan/kg. Speckle-tracking echocardiography was performed to assess the 3 LA phasic functions through LA deformation (longitudinal strain and strain rate) and volumetric analyses. RESULTS Pimobendan significantly increased stroke volume and cardiac output and decreased systemic vascular resistance. Pimobendan significantly improved left ventricular function assessed by the Tei index and LA booster pump function assessed by LA longitudinal strain and change in fractional volume during atrial systole. Indices of LA reservoir and conduit function were unchanged. CONCLUSIONS AND CLINICAL RELEVANCE In healthy dogs, IV administration of pimobendan improved the indices of LA booster pump function but had no effect on the indices of LA reservoir and conduit functions. Further studies are needed to validate whether these results can be extrapolated to dogs with myxomatous mitral valve disease.

Hemodynamic effect of pimobendan following intramuscular and intravenous administration in healthy dogs: A pilot study

“…Despite cardiac catheterization being more accurate than echocardiography in these measurements, cardiac catheterization is more invasive and unsuitable for repeated measurements in each dog ( 51 – 53 ). Moreover, we elected to conduct the study under anesthesia to avoid any fluctuation in cardiac measurements during the handling of animals as previously described ( 22 , 23 ). However, the isoflurane used in the present study has a dose-dependent antihypertensive effect associated with vasodilation and negative inotropic effects as previously reported ( 46 – 49 ); additionally, isoflurane has been reported to increase the HR and LAP and decrease myocardial contractility ( 50 ).…”

“…Hemodynamic properties of pimobendan are different in animals with heart disease compared to healthy dogs and the sensitivity by target site may vary depending on the degree of acidemia and circulatory failure in dogs with CHF. Here we have to say that various routes of injectable pimobendan administration are still under research consideration using animal models or healthy dogs and further clinical studies should be performed (17,(21)(22)(23).…”

“…Oral administration in such cases is more difficult than parenteral routes, and the desired effect of the drug occurs slowly when used per os (17), making it an inappropriate route of administration in emergency cases such as in acute heart failure or severe CHF. Currently, injectable pimobendan has been formulated and became available for IV injection (17, 21), suggesting an alternative live-saving route of administration in case of advanced stages of MVD to rapidly reduce the left ventricular end-diastolic pressure (17,22). Recent studies revealed that the IV administration of pimobendan, but not SC, may be useful in patients with acute heart failure caused by MVD (23,24).…”

“…Currently, injectable pimobendan has been formulated and became available for IV injection ( 17 , 21 ), suggesting an alternative live-saving route of administration in case of advanced stages of MVD to rapidly reduce the left ventricular end-diastolic pressure ( 17 , 22 ). Recent studies revealed that the IV administration of pimobendan, but not SC, may be useful in patients with acute heart failure caused by MVD ( 23 , 24 ).…”

High‐output cardiac failure in a dog secondary to hepatic vascular malformation

“…This decision was made based on studies evaluating intravenous pimobendan in healthy dogs, in which pimobendan resulted in an increased stoke volume, increased cardiac output and decreased systemic vascular resistance. 17,18 Our patient already had evidence consistent with increased stroke volume and increased cardiac output on Echo coupled with the concern for decreased systemic vascular resistance with high-output cardiac failure, thus we ultimately elected not to start pimobendan in our patient. Additional factors taken into account during the clinical decisionmaking process included the absence of data that supports pimobendan administration in patient with high-output cardiac failure and mindfulness of the financial impact on the client.…”