Ventriculo-arterial Coupling Modification Evaluated by PRAM During TAVI Procedure

Calcified aortic stenosis is the most frequent valvulopathy in Europe and North America. Aortic stenosis is an obstacle to the ejection of blood from the left ventricle to the aorta and leads to morphological changes in the left ventricle and hemodynamic modifications. Intrinsic ventricular performance can be characterized using three parameters: * Ventricular elastance (Ees for End Systolic Elastance) which represents the index of ventricular contractility independently of the load. * Arterial elastance (Ea for Arterial Elastance) which represents the post-load * The ventriculo-arterial coupling index (Ees / Ea) which represents energy efficiency. For patients with high surgical risk (EuroSCORE II\> 6), TAVI (Transcatheter Aortic Valve Implantation) is recommended for aortic valve replacement. Many complications may occur after TAVI (haemorrhagic, embolic, renal, myocardial ischemia). Post-TAVI complications may also be cardiac decompensation of the underlying cardiac disease to cardiogenic shock. However, literature on left ventricular performance after aortic valvular replacement is poor because of the difficulty and invasiveness of the analysis involved. Cardiac energy analysis plays an additional role in understanding the clinical patients conditions. On this point, cardiac energy modifications, based on ventriculo-arterial coupling, could be indicators of cardiac function. Two methods (ultrasound and pulse contour) are used to understand and explore the ventriculo-arterial coupling, preload, postload, contractility and hemodynamic changes interactions. Echocardiography allows the Ees / Ea and SW / PVA (Stoke work/ pressure-volume area) ratios mesurements. PRAM (Pressure Recording Analytical Method) through the MostCare® monitor, gives common hemodynamic parameters and more specific parameters such as arterial elastance (Ea) cardiac cycle efficiency (CCE), dP / dt. Cardiac cycle efficiency (CCE) is an exclusive variable that describes the hemodynamic perfo