This is a mechanistic exploratory study. The objective is to determine the effects of the new PFLVAD PulseCath® iVAC2L and the CFLVAD Impella CP on ventricular loading using left ventricular pressure-volume loops, in association with systemic and pulmonary hemodynamic parameters obtained from right and left catheterization. Additionally, assessments of specific load and flow-dependent humoral factors and cardiac enzymes will be made during and after the use of mechanical circulatory support. These specific patterns are so far unknown and will be compared with the LV-to-arterial continuous flow CFLVAD Impella CP. Ten cases treated with Impella CP will be included in this study to obtain the exact same variables for comparing purposes. Knowledge of optimal patterns may help in determining the ideal circulatory device platform. If a difference is demonstrated, a randomized trial could be designed to detect differences in clinical outcomes between pulsatile and continuous flow circulatory support.