C13 - Effects of Zenalpha® (Medetomidine/Vatinoxan) on Blood Pressure, Echocardiographic Measurements, and Cardiac Rhythm in Healthy Dogs

Abstract:

Background: The effect of Zenalpha® (medetomidine/vatinoxan) on echocardiographic parameters and cardiac rhythm in healthy adult dogs has not been evaluated.

Hypothesis/Objectives: To determine the effects of Zenalpha® on blood pressure, echocardiographic parameters, and cardiac rhythm in healthy dogs.

Animals: Twenty-one healthy, adult, client-owned dogs

Methods: Dogs were enrolled in a prospective, pre-test/post-test study. Echocardiography, blood pressure, and 1-hour Holter monitor were performed at baseline and repeated after sedation with Zenalpha® (1mg medetomidine/m²). Multiple echocardiographic parameters (M-mode, 2D, volumetric-SMOD, Doppler, and tissue Doppler), blood pressure, and an arrhythmic burden score were assessed using pairwise comparisons between baseline and sedation.

Results: Compared to baseline, Zenalpha® sedation was associated with significant changes in the following parameters: reduction in blood pressure (p< 0.001), prolongation of PR (p< 0.001) and QT (p< 0.001), reduction in HR (p< 0.001), and reduction in eight systolic function parameters: EF (MM,2D,SMOD), %FS (MM,2D), ESVI (SMOD), SVI (SMOD), %LVAS (2D), all p< 0.001; and an increase in arrhythmic burden score (p=0.006). Thirteen of 21 dogs (62%) developed or had worsening of AV nodal conduction on Holter while only 2/21 (9.5%) developed or had worsening atrial or ventricular ectopic activity. Of all measured echocardiographic systolic function parameters, 12/21 (57%) dogs had two or more outside of reference range with Zenalpha® sedation. Of the parameters EF-SMOD, ESVI, %FS, and %LVAS, 5/21 (24%) had two or more outside of reference range.

Conclusions and Clinical Importance: Sedation with Zenalpha® can result in altered ECG and echocardiographic measurements, which should be considered when used for echocardiographic studies.