In vitro testing of a left ventricular assist device Study of the effect of its control strategy on energetic relationships inside the left ventricle

Abstract

In this study an original left ventricular assist device is tested on an open loop modular physical circuit reproducing Starling’s law of the heart to set an optimal control strategy for heart recovery. It is assumed that the goals of the assistance are reduction of oxygen consumption, external work and improvement of cardiac mechanical efficiency. The assistance is evaluated by the position of a working point on the characteristic surfaces of the ventricle defined by peripheral resistance, atrial pressure and selected variables pertaining to energy (pressure-volume area, external work and cardiac mechanical efficiency). In this frame an optimal assistance for heart recovery is a compromise among different requirements corresponding to a restricted set of control parameters values: driving pressure ${\mathit{P}}_{{\mathit{Z}}_{\mathit{B}}}=35\mathrm{kPa}$ and timing values T₁ and T₂ (systole beginning and systole ending in relation to QRS complex and cardiac cycle duration T) ${\mathit{T}}_1=0.55·\mathit{T}$ and ${\mathit{T}}_2=0.73·\mathit{T}$ .