[Echocardiographic determination of left ventricular function during isometric muscle exertion and the Valsalva...

Left ventricular dimensions and function were estimated in 11 healthy volunteers by means of echocardiography during isometric exercise and the Valsalva manoeuvre. Isometric exercise induces a rise of heart rate and Vcf by 14% and of cardiac output as well as of the cardiac index by 12%. Stroke volume remains unchanged. During Valsalva's manoeuvre a marked decrease in left ventricular dimensions is observed. A reduction of the stroke volume by 29% was not compensated by increasing heart rate. However, cardiac output and cardiac index is found 10% below control values.