A previous study by Little et al.12) showed decreased AVA by acute BP elevation induced by phenylephrine infusion and hand grip exercise. They suggested that the impact of BP change is associated with transvalvular flow rate through aortic valve without relation to SVR or SAC. In this study, we adopted Pcom instead of hand grip exercise or phenylephrine infusion because
these methods augment Inhibitors,research,lifescience,medical heart rate and induce a significant change in ejection time, as previously described. Because our study was free from changes in HR and LV ejection time under Pcom, an impact of LV afterload change on AVA assessment can be exclusively assessed, which is, we believe, a significant advantage of the current study. LIMITATIONS Pcom is a useful method to increase LV afterload without change of preload or HR when compared to other methods, Inhibitors,research,lifescience,medical such as hand grip exercise or phenylephrine infusion.12) However, Pcom possibly increases the venous return from lower extremities, which could explain, to some extent, increased E velocity, and slightly increased LV end-diastolic dimension. However, Inhibitors,research,lifescience,medical a previous study clearly
demonstrated that the primary mechanism whereby Pcom induced changes in hemodynamics is through an acute increase in LV afterload.13) In addition, a change in LV CO was minimal, highlighting the impression that hemodynamic effect by venous return for cardiac performance was, if any, negligible. Simulation of arterial BP elevation by Pcom also has a limitation for SVR increase alone, and cannot increase Inhibitors,research,lifescience,medical aortic stiffness which is more important
in essential hypertension in elderly patients. We also cannot directly measure LV systolic wall stress and central BP, because we did not perform invasive monitoring of intra-LV pressure and central BP, however, SVR and SAC that were employed in the current study were previously p38 kinase assay validated against invasively obtained hemodynamic data as indirect indexes for LV afterload.14),15) CONCLUSIONS Assessment of AS severity by routine transthoracic echocardiography was Inhibitors,research,lifescience,medical not significantly influenced by a change in LV afterload. AV Vmax could be slightly decreased PAK6 when LV afterload rises, but these changes did not seem to exert a significant influence on clinical decision making in managing AS patients. EOAAV and Doppler velocity index is more stable method for evaluation of AS severity than AV Vmax, and therefore these 2 indexes should be used in the determination of AS severity, rather than AV Vmax or TPG of AV. Acknowledgements This study was supported by an Industry-Academy grant of the Korea Society of Echocardiography (2008, Chang SA).
In a mitral valve with functional MR, geometric abnormalities of incomplete valve coaptation at systole are mainly characterized by leaflet tethering due to displacement of PMs and flattening of mitral annulus.