Stress echocardiography in aortic stenosis: Insights into valve mechanics and hemodynamics

Stress interventions have been classically combined with cardiac catheteriz ation recordings to understand the hemodynamic principles of valvular steno sis. Indices of aortic stenosis such as pressure gradient and valve area we re based on, simple hydraulic principles and have proved to be clinically u seful for patient management during a number of decades. With the advent of Doppler echocardiography, these hemodynamic indices can. be readily obtain ed noninvasively. Abundant evidence obtained using exercise and pharmacolog ical stress echocardiography has demonstrated that the assumptions of class ic hemodynamic models of aortic stenosis were wrong. Consequently, it is re cognized that conventional indices may be misleading indicators of aortic s tenosis significance in particular clinical situations. To improve diagnost ic accuracy, several alternative hemodynamic models have been developed in the past few years, including valve resistance and left ventricular stroke work loss, among others. Nevertheless, these more-accurate indices should b e obtainable noninvasively and need to demonstrate greater diagnostic and p rognostic power than conventional indices; preliminary data suggest such su periority. Stress echocardiography is well established as the tool of choic e for testing hypothesis and physical models of cardiac valve function. Alt hough the final role of alternative indices is not yet well established, th e new insights into valvular hemodynamics provided by this technique may ch ange the clinical assessment of aortic stenosis.