Noninvasive Diagnostics in Left Ventricular Assist Device Patients

* Background: In recent years Left Ventricular Assist Devices (LVADs) have become the devices of choice to treat patients with advanced heart failure. Proper evaluation of the cardiovascular function under LVAD support is of key importance especially for the preservation of the assisted cardiac function or for the evaluation of an eventual cardiac recovery. Cardiac echocardiography, electrocardiography and catheterization, as well as exercise testing are the standard clinical methods for the evaluation of the cardiovascular function during LVAD support. All these methods require however time-consuming procedures, and are therefore unacceptably cumbersome for frequent monitoring. On the other hand, a frequent and effective noninvasive evaluation of the cardiac status provided by the LVAD itself would have a remarkable impact on LVAD patients and their therapy. Previously developed methods to assess the cardiovascular status from data available from the LVAD (see references given) will be now investigated in a prospective clinical study. * Purpose: The main purpose of this study is evaluate the sensitivity/specificity of LVAD based diagnostics when compared to standard clinical diagnostic procedures both at rest and during exercise. Secondarily, the physical activity of patients will be evaluated following LVAD implantation. * Methods: Seventy-five heart failure patients who had or are about to have a LVAD implanted will be enrolled in this study. In these patients, the LVAD data (motor current and speed) will be recorded concurrently to the routine clinical examinations and during daily life. The routine clinical examinations typically consist of a subset of the following procedures: cardiac ultrasound, cardiac catheterization, 24h ECG measurement, exercise tests (6-minute walk test and spiroergometry). Parameters from the LVAD data that reflect contractile and relaxation properties as well as and aortic valve opening will be compared to echocardiography. Parameters from the LVAD data that reflect cardiac rhythms will be compared to ECG measurements. Both cardiac hemodynamics and rhythms during exercise tests will be assessed using the developed methods based on LVAD data. Finally, wristwatch accelerometers will be used for a quantification and evaluation of patient daily life activity. This measurements will be compared to 6-minute walk test and spiroergometry data as well as with the diagnostics methods based on the LVAD data.