Juraj Dúbrava
There exist two situations in aortic stenosis (AS) in which therapeutic decision is not easy: 1. asymptomatic severe AS, 2. AS with low flow, low transvalvular gradient and important left ventricular systolic dysfunction. The indication of the valvular replacement is given in both situations by the result of the bicycle/treadmill stress test or stress echocardiography. In severe asymptomatic AS stress test is the decisive examination. Stress test induced occurrence of the symptoms of AS is the unambiguous indication for valvular replacement. There is also the tendency towards the surgery in drop of systolic blood pressure below the baseline value. In AS with low gradient and left ventricular systolic dysfunction it is necessary to distinguish true severe AS from pseudosevere AS. The method of choice is dobutamine stress echocardiography (DSE). Severe AS is characterized by an important increase of maximal transvalvular gradient and time-velocity integral (TVI) without the change of the orifice area. In pseudosevere AS dobutamine stress will result in significant increase (> 0,2 cm2) in valve area without the change of both maximal transvalvular gradient and TVI. DSE allows also the evaluation of the contractile reserve, which is major predictor of operative risk and profit from valvular replacement.