Noninvasive Diagnostics in Left Ventricular Assist Device Patients

* Study Purpose: The purpose of this study is to evaluate the sensitivity/specificity of noninvasive diagnostic methods for the cardiac function that are based on data available from the Left Ventricular Assist Device (LVAD). These diagnostic methods will be compared to standard clinical diagnostic procedures both at rest and during exercise. * Study Design: The study is a prospective interventional cohort study. * Patient cohort: Thirty heart failure patients who had or are about to have a LVAD implanted. * Data Collection: The acquisition of LVAD data (motor current and speed) and wristwatch accelerometry data concurrently to the documentation of routine clinical examinations, such as cardiac ultrasound, electrocardiography (ECG), cardiac catheterization, and exercise tests, will be performed.