Control systems for rotary blood pumps

Abstract

The present invention generally relates to a control system for a rotary blood pump adapted to move blood in a patient. The control system comprises a means for measuring and varying the speed of the pump and a means for measuring the pulsatility index of a patient, and the control system is adapted to maintain the pulsatility index at or near a predetermined value by varying the speed of the pump. The pulsatility index is derived from the amplitude of the actual pump speed over a predetermined time period. Optionally, also, the control system can calculate the second derivative of instantaneous speed of the rotary blood pump and use the calculation of the second derivative of instantaneous speed to detect a suction event, and help prevent it.

Description

TECHNICAL FIELD [0001] The present invention relates to improvements to control systems for a rotary blood pump. BACKGROUND ART [0002] To treat cardiac insufficiency or failure, heart assist devices have been used to assist the heart of a patient. These heart assist devices include various pumping devices. A high level of success has been attributed to a particular group of heart assist devices called rotary blood pumps. [0003] In the past, the rotary blood pumps have used control systems which set the pumping speed at a constant rate. This constant rate would not change for the physiological demands of the patient. Therefore, if a patient was exercising the physiological demands for increased blood supply would not be offset by a matched increased pumping rate or speed of the rotary blood pump. [0004] Therefore, there is a need for a control system that allows a rotary blood pump to match the physiological needs of a patient. [0005] Rotary blood pumps also usually provide a continu...

AI Technical Summary

Benefits of technology

[0010] Preferably, the control system determines imminence of a suction event based on the stroke work. Preferably, the target speed is pulsed in cooperation with the heart. Preferably, the control system includes a selective mode that minimises target pump speed to achieve forward blood flow through both the pump and aortic valve, whilst avoiding retrograde flow. Preferably, the selective mode sets target speed at about 1250 rpm.

[0012] In accordance with a second aspect, the present invention consists of a control system for use with rotary blood pumps, wherein the control system includes a selective mode that minimises target pump speed to achieve forward blood flow through both the pump and aortic valve, whilst avoiding retrograde flow.

Problems solved by technology

Rotary blood pumps operating at predetermined fixed pumping rate often tend to over-pump or under-pump blood from the ventricle depending on the physiological needs of the patient and this may lead to deleterious effects on the patient including, but not limited to, suction events or ventricular collapse.

The net result is a partial or complete collapse of the ventricle.

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