View clinical trials related to Endothelial Cells.
Filter by:The study will compare two invasive methods (FFR -fractional flow reserve and iFR—instantaneous wave free ratio) for assessment of hemodynamic impact of coronary stenosis on myocardial perfusion. There is a very good correlation between these methods for the assessment of hemodynamic significance in a broad spectrum of lesions. However, this correlation decreases significantly near the cut off points for each method. The investigators will try to find possible explanations for these differences by detailed morphology assessment of coronary stenosis using optical coherence tomography (OCT), analysis of gene polymorphisms that play a role in vasodilatation, and by shear stress analysis. The head-to-head comparison between FFR and iFR is not simple, because there is no "gold standard" for assessment of hemodynamic significance. Studies comparing these methods have used hyperemic stenosis resistance (HSR). For this kind of measurement it is necessary to measure the speed of blood flow. This is usually done by a Doppler analysis of flow. Unfortunately, the Doppler signal can yield many artificial or erroneous indicators, and obtaining a good quality signal is frequently time-consuming. These are the reasons that HSR has not been used in routine practice. The investigators have developed a new console and software that can provide real time analysis of the Doppler signal. It allows us to easily measure HSR, and to differentiate between the FFR and iFR measures through intrabeat analysis of microvascular resistance (lowest microvascular resistance is an essential condition for proper pressure measurement). Using this tool, it is possible to automatically identify the point of lowest microvascular resistance during each cardiac beat. The pressure gradient can then be measured at that point. This approach can eliminate almost all uncertainties in assessment of the pressure gradient produced by coronary stenosis. This tool can potentially improve the existing methods used to precisely reveal a significant stenosis. This should increase the number of hemodynamic guided procedures.
This is a non-randomized feasibility study of endothelial function, exercise capacity, and outcome following pre-left ventricular assist device (LVAD)therapy and cardiac transplant. The study period will be 5 years, with 20 patients to be enrolled. The investigators anticipate that 15 patients will survive to complete the one year follow up period.(the published survival rate of LVAD is 75% in one year). 10 patients are anticipated to undergo cardiac transplant within 3 years of initial enrollment and they are followed until their 2nd annual post transplant invasive evaluation. Markers of endothelial function will be studied to permit comparison with selected clinical outcomes. The hypothesis is that the endothelial functions will be altered after implantation of LVAD then before its implantation, both acutely and chronically, and this may affect the exercise capacity, quality of life and occurrence of cardiac allograft vasculopathy post cardiac transplantation.