The assessment of left ventricular response to stress in the rat using uobutamote stress echocardiography

Purpose: The use of echocardiography in determining cardiac response UP stress in the rat model has not yet been reported. We tested the utility of dobutamine stress echocardiography (DSE) in quantifying, systolic functional reserve in rats. Methods: We imaged normal rats (WKY; n=5) and compared them to rats with left ventricular hypertrophy (SHR; n-5) using a graded dose of dobutamine. Under anaesthesia, cardiac structure and function were assessed using a Toshiba Powervision SHA380 with a 7.0 Mhz transducer (frame rate upto 168/sec). Left ventricular mass (LVM) was derived using the cube formula and stroke volume (SV) from the pulmonary artery velocity time integral. To assess the ability of DSE to detect changes in cardiac performance under stress, rats were imaged at baseline and immediatley after incremental doses of intraperitorieal dobutamine. Results: LVM differed in SHR and WKY rats (1275173 vs 723±38 mg, p<0.001). In WKY rats, an incremental dose of dobutamine increased stroke volume (r ²=0.95 p<0.05) while no such change occured in SHR (r ²=40.34 p>0.05) SV mls Baseline 5μg/kg 15μg/kg 50μ/kg SHR 0.28±0.02 0.31±0.04 0.30±0.03 0.30±0.04 WKY 0.19±0.01 0.22±0.02 0.24±0.02 0.24±0.02 Conclusions: 1)DSE can quantify cardiac functional reserve in rats. 2) Rats with LVH have higher resting SV but blunted response to dobutamine compared to normals. 3)DSE may be useful for noninvasive assessment of rats subjected to therapeutic or genetic intervenue :is.