Echocardiography Alone Allows the Determination of Heart Failure Stages in Rats with Pressure Overload

BackgroundThere is currently no standard for the assessment of contractile function in animals. We aimed to determine whether transthoracic echocardiography in rats with chronic pressure overload allows determining the stage of hypertrophy and heart failure (HF). MethodsPressure overload was created by placement of a metal clip around the thoracic aorta at a weight of 40 to 50 g. After 1, 2, 6, 10, and 20 weeks, we performed echocardiography according to the American Heart Association guidelines (n=26, four to six rats for each time point). We also obtained heart, lung, and body weights and regularly evaluated clinical signs of HF. ResultsPressure overload caused significant hypertrophy within 1 week. Contractile function was normal until 6 weeks when diastolic dysfunction appeared. After 10 weeks of pressure overload, systolic function decreased. At 20 weeks, hearts were dilated and cardiac index was decreased. These findings correlated with increased lung-to-body weight ratio after 6 weeks and clinical signs of HF after 20 weeks. ConclusionEchocardiography alone allows the reproducible determination of HF stages after aortic constriction in rats.