Control Strategy for Rotary Blood Pumps

Abstract

The control strategy for ventricular support with a centrifugal blood pump was examined in this study. The control parameter was the pump rpm that determines pump flow. Optimum control of pump rpm that reflects the body's demand is important for long-term, effective, and safe circulatory support. Moreover, continuous, reliable monitoring of ventricular function will help successfully wean the patients from the ventricular assist device (VAD). The control strategy in this study includes determination of the target pump rpm that can provide the flow required by the body, fine-rpm-tuning to minimize deleterious effects such as suction in the ventricle, and assessment of ventricular function for successful weaning from VADs. To determine the target pump rpm, we proposed to use the relation between the native heart rate and cardiac output, and the relation between the pump rpm and centrifugal pump output. For fine-tuning of the pump rpm, the motor current waveform was used. We computed the power spectral density of the motor current waveform and calculated the ratio of the fundamental to the higher order components. When this ratio was larger than approximately 0.2, we assumed there would be a suction effect in the ventricle. As for assessment of ventricular function, we used the amplitude of the motor current waveform. The control system implemented using a DSP functioned properly in the mock circulatory loop as well as in acute animal experiments. The motor current also showed a good correlation with the ventricular pressure in acute animal experiments.

Numerical Modeling of Hemodynamics with Pulsatile Impeller Pump Support

“…Vandenberghe et al compared the unloading effect of the Medos Micro microdiagonal rotary blood pump under both continuous and pulsatile modes, 31 and also studied the hemodynamic modes of ventricular assist with Medos DeltaStream rotary blood pump in continuous and pulsatile modes. 29 In their studies of VAD control strategy design, Giridharan et al 6 and Ohuchi et al 16 modulated the speed of the rotary blood pump and produced pulsation of arterial pressure covering the physiological range of 80-120 mmHg. In all of these studies, emphasis has been only either on damage to blood cells in the pump or on certain limited aspects of cardiovascular dynamics.…”

Bomba sangüínea espiral: concepção, desenvolvimento e aplicação clínica de projeto original

“…The hemolysis is the motive of extensive researches in the development of devices of blood propulsion [20][21][22][23][24][25] by starting from the presupposed that it is impossible to avoid the mechanical hemolysis caused by a propulsion device and, besides that it has been checked through different indexes making comparisons often difficult [21]. The definition of the "in vitro" Hemolysis index was established by the amount of Free Hemoglobin per 100 liters of pumped blood with fresh blood and hemoglobin e" 14 g/dL and if its deposit was located 140 cm above the pump [26,27].…”

Left Ventricular Heart Assist Device using MC and ECG Feedback

“…The highest speed of the pump is limited by induction of suction in the left ventricle, which occurs when the LVAD attempts to pump more blood from the ventricle than is available. Suction can be deleterious to the myocardium, blood, and lungs [6].…”