Echocardiographic assessment of cardiac function in conscious and anesthetized mice

Using a high-frequency linear transducer (15L8), we studied 1) the feasibil ity of performing echocardiography in nonanesthetized mice compared with mi ce given pentobarbital sodium (Pento) or a mixture of ketamine and xylazine and 2) the feasibility of echocardiographic evaluation of left ventricular (LV) hypertrophy, dilatation, and function in mice with two-kidney; one-cl ip hypertension or myocardial infarction (MI). Heart rate (HR) in awake mic e was 658 +/- 9 beats/min; Pento and ketamine plus xylazine reduced HR to 3 77 +/- 11 and 293 +/- 19 beats/min, respectively, associated with a signifi cant decrease in shortening fraction (SF), ejection fraction (EF), and card iac output (CO) and an increase in LV end-diastolic (LVEDD) and end-systoli c dimensions (LVESD). Mice with 4 wk of two-kidney, one-clip hypertension h ad increased LV mass (15.62 +/- 0.62 vs. 22.17 +/- 1.79 mg) without altered LV dimensions, SF, EF, or CO. Mice studied 4 wk post-MI exhibited obvious LV dilatation and systolic dysfunction, as evidenced by increased LVEDD and LVESD and decreased SF, EF, and CO. Our findings clearly show the adverse impact of anesthesia on basal cardiac function and the difficulty in interp reting data obtained from anesthetized mice. We believe this is the first s tudy to demonstrate the feasibility of using echocardiography to assess car diovascular function in the nonanesthetized mouse.