The safety system for the rotary blood pump, combination of the valve and LVAD pulsatile mode: In vitro test

The significant amount of regurgitation produced by a stopped rotary blood pump is one of the major considerations for its use as an implantable left ventricular assist device (LVAD), especially if the pump accidentally stops. The installation of a valve is an option for the solution of this potential problem. However, this option may lead to thrombogenic problems, particularly if the valve motion is restricted. This in vitro study analyzes the valve performance and assesses the credibility of a rotary blood pump valve. A pulsatile pump was used as the natural heart and a centrifugal pump as the LVAD. The valve was positioned into the LVAD outflow. In the low speed range (<1,000 rpm in this test condition), normal valve motion was maintained. Also, the valve model provided a higher mean bypass flow than the model without a valve due to reduced regurgitation. However, the valve motion was drastically restricted when in the high speed range (>1,600 rpm in this condition). The pulsatile mode was applied to the LVAD by periodically changing the impeller speed (40 bpm); subsequently, a constant valve motion could be provided. A possibility exists that this pulsatile mode application could eliminate thrombosis formation around the valve. A conclusion was made that the combination of a valve and an LVAD in a pulsatile mode is considered to be a unique safety system for a rotary blood pump.