- The Patent is a SYSTEM for controlling the speed at which the...

- The Patent is a SYSTEM for controlling the speed at which the Ventrassist pumps (pumping at the same rate as the natural cardiac cycle).

- This invention is important because it aims to address one or more of the disadvantages associated with previous pump speeds:

- Examples are;

1. other types of control systems often fail to sufficiently mimic the natural cardiac cycle of a patient in which the circulatory system experiences a pulsed blood flow and/or pressure.

2. prone to mechanical failure as well as thrombogenesis or blood clotting occurring around the valves. These types of cardiac assist devices are commonly classified as first generation assist devices.

3. potential thrombogenesis and is generally not preferred for patient safety.

4. may subject the blood to relatively high pressures at the times of ejection and may cause haemolysis to occur in the blood.

5. patient's risk of infections, complications and blood clotting.

SUMMARY OF THE INVENTION

The present invention consists in a system for controlling the speed of a rotary blood pump, wherein said system oscillates the speed of said pump to produce pulsed pressure at the outlet of said pump, wherein the speed is oscillated synchronously with the natural cardiac cycle and characterised in that the natural cardiac cycle is determined using a pulsatility index calculated from the back EMF produced by the pump.

The most preferred rotary blood pump for use with the present invention or embodiments is the Ventrassist(U.S. Pat. No. 6,227,797--Watterson et al).

The most preferred rotary blood pump may also include a magnetically suspended or levitated impeller.