Implantable pump impeller thermal knockdown

Patent metadata

Field	Value
Publication number	US-2018085508-A1
Application number	US-201715719719-A
Country	US
Kind code	A1
Filing date	Sep 29, 2017
Priority date	Sep 29, 2016
Publication date	Mar 29, 2018
Grant date	—

Abstract

The present invention relates to kits and methods for calibrating a pump through performance of a thermal knockdown process including demagnetization of an impeller of the pump where the impeller is separate from the pump. By heat treating the impeller, a property of magnetic interaction of the pump is reduced in a repeatable manner. A kit includes a pump with impeller, a controller and an oven. The method generally involves an iterative process of testing the pump for a property related to magnetic interaction of the elements of the pump, removing the impeller from the pump, heating the impeller under controlled conditions, then placing the impeller back into the pump to repeat the test performed initially.

First claim

What is claimed is:

1 . A method of modifying a property related to a magnetic interaction between an impeller having permanent magnetization and a blood pump including a stator, comprising:
(a) heating the impeller until the property reaches a target value.

2 . The method of claim 1 , further comprising:
(b) measuring the property of the blood pump prior to heating the impeller; and (c) selecting at least one condition of heating the impeller based on the measured property of the pump.

3 . The method of claim 2 , wherein the at least one condition is a temperature used in heating the impeller.

4 . The method of claim 3 , wherein the selecting is conducted using (i) a difference between the measured property of the pump prior to heating the impeller and the target value of the property and (ii) data relating change in the property to treatment temperature compiled from experimental data obtained in previous heating of impellers of one or more blood pumps of the same nominal configuration.

5 . The method of claim 4 , further comprising separating the impeller from the stator after the measuring and before heating the impeller, and combining the impeller with the stator after the heating.

6 . The method of claim 2 , further comprising repeating steps (a)-(c) with the same blood pump, and wherein repeating steps (a)-(c) includes selecting a second condition for heating the impeller.

7 . The method of claim 6 , further comprising repeating steps (a)-(c) with a plurality of different blood pumps.

8 . The method of claim 2 , wherein the measuring includes pumping a test fluid of known viscosity at a fixed test flow rate of fluid and a fixed test impeller speed with the blood pump.

9 . The method of claim 1 , wherein the impeller includes a magnetic alloy selected from the group consisting of platinum-cobalt alloys and platinum-cobalt-boron alloys.

10 . The method of claim 9 , wherein the magnetic alloy is a platinum-cobalt alloy containing about 77% platinum and 23% cobalt.

11 . The method of claim 1 , wherein heating the impeller includes exposing the impeller to a predetermined temperature above ambient temperature until a temperature of the impeller is substantially equal to the predetermined temperature above ambient temperature.

12 . The method of claim 11 , wherein the predetermined temperature is at least 73 degrees Celsius.

13 . The method of claim 1 , wherein the property is back electromotive force.

14 . A method of modifying at least one blood pump including a stator and an impeller with permanent magnetization, comprising:
heating the impeller for a first heating cycle at a first temperature; measuring a property related to magnetic interaction between the impeller and the stator; and if a value of the property related to magnetic interaction after the first heating cycle is greater than a predetermined target value of the property, heating the impeller for a second heating cycle at a second temperature higher than the first temperature.

15 . The method of claim 14 , wherein the property equals the predetermined target value of the property after the second heating cycle.

16 . The method of claim 14 , wherein the first temperature of the first heating cycle is maintained until a temperature of the impeller is substantially equal to the first temperature.

17 . The method of claim 12 , wherein the first temperature is at least 73 degrees Celsius.

18 . A kit for calibrating a pump having a stator and an impeller, comprising:
a heater sized and configured to heat treat the impeller; and a controller configured to measure back electromotive force related to a magnetic interaction between the impeller having permanent magnetization and the blood pump including the stator.

19 . The kit of claim 16 , wherein the heater is configured to heat treat the impeller based on a comparison of the back electromotive force measured by the controller and a target back electromotive force value.

20 . The kit of claim 16 , wherein the impeller is made of a platinum cobalt alloy.

Assignees

• Heartware Inc

Inventors

• Wolman Justin
• Reyes Carlos
• Casas Fernando

Classifications

• A61M1/1036

  Human Necessities · mapped topic

• A61M2205/3368

  Temperature · CPC title

• F04D29/18 Primary

  Rotors (specially for elastic fluids F04D29/26) · CPC title

• F04D13/0653

  the motor being flooded · CPC title

• F04D27/001

  Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring · CPC title