The Impact of Pump Speed and Inlet Cannulation Site on Left Ventricular Unloading with a Rotary Blood Pump

Summary Objectives: Aim of this work is to study the impact of left ventricular rotary blood pump assistance, on energetic variables, when mechanical ventilation (MV) of the lungs is applied. Methods: Computer simulation was used to perform this study. Lumped parameter models reproduce the circulatory system. Variable elastance models reproduce the Starling’s law of the heart for each ventricle. After the reproduction of ischemic heart disease left ventricular assistance was applied using a model of rotary blood pump. The pump speed was changed in steps and was assumed to be constant during each step. The influence of mechanical ventilation was introduced by different values of positive mean thoracic pressure. Results: The increase of the rotational speed has a significant influence on some ventricular energetic variables. In fact it decreased left ventricular external work, left and right ventricular pressure-volume area and the left ventricular efficiency. Finally, it increased the right ventricular efficiency but had no influence on the right ventricular external work. The increase of thoracic pressure from –2 to +5 mmHg caused a significant decrease of external work, pressure-volume area (right ventricular pressure-volume area dropped up to 50%) and an increase of right ventricular efficiency (by 40%) while left ventricular efficiency remained almost stable. Conclusions: Numerical simulation is a very suitable tool to predict changes of not easily measurable parameters such as energetic ventricular variables when mechanical assistance of heart and/or lungs is applied independently or simultaneously.

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Preliminary evaluation of a predictive controller for a rotary blood pump based on pulmonary oxygen gas exchange

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411918823035 ◽

2019 ◽

Vol 233 (2) ◽

pp. 267-278 ◽

Cited By ~ 1

Author(s):

Feng Huang ◽

Zhe Gou ◽

Yang Fu

Keyword(s):

Gas Exchange ◽

Oxygen Partial Pressure ◽

Partial Pressure ◽

Left Ventricular ◽

Blood Pump ◽

Rotary Blood Pump ◽

Blood Pumps ◽

Control Objective ◽

Predictive Controller ◽

Rotary Blood Pumps

Physiological control of rotary blood pumps is becoming increasingly necessary for clinical use. In this study, the mean oxygen partial pressure in the upper airway was first quantitatively evaluated as a control objective for a rotary blood pump. A model-free predictive controller was designed based on this control objective. Then, the quantitative evaluation of the controller was implemented with a rotary blood pump model on a complete cardiovascular model incorporated with airway mechanics and gas exchange models. The results show that the controller maintained a mean oxygen partial pressure at a normal and constant level of 138 mmHg in the left heart failure condition and restored basic haemodynamics of blood circulation. A left ventricular contractility recovery condition was also replicated to assess the response of the controller, and a stable result was obtained. This study indicates the potential use of the oxygen partial pressure index during pulmonary gas exchange when developing a multi-objective physiological controller for rotary blood pumps.

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