Heart beat identification and pump speed synchronization

Patent metadata

Field	Value
Publication number	US-2016228628-A1
Application number	US-201615041716-A
Country	US
Kind code	A1
Filing date	Feb 11, 2016
Priority date	Apr 30, 2013
Publication date	Aug 11, 2016
Grant date	—

Abstract

A method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle includes obtaining a signal from a motor of a heart assist pump device and filtering the signal to remove noise. The method also includes determining a speed synchronization start point at which time the motor of the heart assist pump device will begin a change in speed of operation based on the filtered signal. The method further includes modulating a speed of the motor of the heart assist pump device to a target speed at the speed synchronization start point, thereby synchronizing the change in speed of operation with a patient's cardiac cycle.

First claim

What is claimed is:

1 . A method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle, wherein the method comprises:
obtaining a signal from a motor of a heart assist pump device; filtering the signal to remove noise; determining a speed synchronization start point at which time the motor of the heart assist pump device will begin a change in speed of operation based on the filtered signal; and modulating a speed of the motor of the heart assist pump device to a target speed at the speed synchronization start point, thereby synchronizing the change in speed of operation with a patient's cardiac cycle.

2 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 1 , wherein the signal comprises:
a current signal or a power signal.

3 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 1 , wherein filtering the signal comprises:
employing a second order impulse response filter.

4 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 1 , wherein determining the speed synchronization start point comprises:
determining, for at least two consecutive prior pulses, whether each of the at least two consecutive prior pulses are complete; and determining a pulse period based on the filtered signal.

5 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 4 , wherein determining whether a pulse is complete comprises:
determining that Diff max2Mean [i] is (1) greater than a first product of c 1 and Diff max2Min [i]; and (2) is lesser than a second product of c 2 and Diff max2Min [i]; and determining that four pulse periods comprising T f2f [i], T r2r [i], T min2min [i], and T max2max [i] are each (1) greater than T cyc _ min , and (2) less than T cyc _ max .

6 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 4 , wherein the determining a pulse period comprises:
determining the median of T f2f [i], T r2r [i], T min2min [i], and T max2max [i].

7 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 1 , wherein determining the speed synchronization start point comprises:
using a maximum amplitude time point as a reference when T max2max [i] is most close to T cyc [i] such that the speed synchronization start point is equal to t max [i]+T cyc [i]−T sp , where T sp is the duration of the increase in speed of operation; using a minimum amplitude time point as the reference when T min2min [i] is most close to T cyc [i] such that the speed synchronization start point is equal to t min [i] T cyc [i]+T k1 , where T k1 =k 1 T min2max , and k 1 =0.25 to 0.4, which depends on the T sp ; using a falling-crossing time point as the reference when T f2f [i] is most close to T cyc [i] such that the speed synchronization start point is equal to t f [i+1]+τ f2min +T k1 , where τ f2 min is the average of T f2min , and T k1 =k 1 T min2max ; or using a rising-crossing time point as the reference when T r2r [i] is most close to T cyc [i] such that the speed synchronization start point is equal to t r [i]+T cyc [i]−T k2 where T k2 =k 2 T min2max , and k 2 ≈0.125 to 0.3, which depends on the T sp .

8 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 1 , wherein the method further comprises:
increasing the speed of operation of the heart assist pump device at additional speed synchronization start points as determined by
t sync [j]=t sync [0]− T offset +( j− 1)* T cyc [i], where T offset <T min2max and T offset ≈40˜80 ms.

9 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 1 , wherein filtering the signal comprises:
employing one or both of an infinite impulse response filter and a finite impulse response filter.

10 . The method for synchronizing operation of a heart assist pump device to a patient's cardiac cycle of claim 1 , wherein the heart assist pump device comprises:
a left ventricular assist device or a right ventricular assist device.

11 . A heart assist pump device, comprising:
a motor; and a controller, wherein the controller is configured to:
obtain frequency range data from the motor;
determine a speed synchronization start point at which time the motor of the heart assist pump device will begin a change in speed of operation based on the frequency range data; and
modulate a speed of the motor to a target speed at the speed synchronization start point, thereby synchronizing the change in speed of operation with a patient's cardiac cycle.

12 . The heart assist pump device of claim 11 , wherein obtaining frequency range data comprises:
filtering out data that is not less than about 5 Hz.

13 . The heart assist pump device of claim 12 , wherein filtering out data comprises:
employing one or both of a finite impulse response filter and an infinite impulse response filter.

14 . The heart assist pump device of claim 11 , wherein determining the speed synchronization start point comprises:
determining, for at least two consecutive prior pulses, whether each of the at least two consecutive prior pulses are complete; and determining a pulse period based on the filtered signal.

15 . The heart assist pump device of claim 14 , wherein determining whether a pulse is complete comprises:
determining that Diff max2Mean [i] is (1) greater than a first product of c 1 and Diff max2Min [i]; and (2) is lesser than a second product of c 2 and Diff max2Min [i]; and determining that four pulse periods comprising T f2f [i], T r2r [i], T min2min [i]; and T max2max [i] are each (1) greater than T cyc _ min , and (2) less than T cyc _ max .

16 . The heart assist pump device of claim 14 , wherein determining a pulse period comprises:
determining the median of T f2f [i], T r2r [i], T min2min [i], and T max2max [i].

17 . The heart assist pump device of claim 11 , wherein determining the speed synchronization start point comprises:
using a maximum amplitude time point as a reference when T max2max [i] is most close to T cyc [i] such that the speed synchronization start point is equal to t max [i]+T cyc [i]−T sp ; where T sp is the duration of the increase in speed of operation; using a minimum amplitude time point as the reference when T min2min [i] is most close to T cyc [i] such that the speed synchronization start point is equal to t min [i]+T cyc [i]+T k1 , where T k1 =k 1 T min2max , and k 1 ≈0.25 to 0.4, which depends on the T sp ; using a falling-crossing time point as the reference when T f2f [i] is most close to T cyc [i] such that the speed synchronization start point is equal to t f [i+1]+τ f2min +T k1 , where τ f2min is the average of T f2min , and T k1 =k 1 T min2max ; or using a rising-crossing time point as the reference when T r2r [i] is most close to T cyc [i] such that the speed synchronization start point is equal to t r [i]+T cyc [i]−T k2 where T k2 =k 2 T min2max , and k 2 ≈0.125 to 0.3, which depends on the T sp .

18 . The heart assist pump device of claim 11 , wherein the controller is further configured to:
increase the speed of operation of the heart assist pump device at additional speed synchronization start points as determined by
t sync [i]=t sync [0]− T

Assignees

• Thoratec Corp

Inventors

• Medvedev Alexander
• Yu Shunzhou
• You Ren

Classifications

• A61M1/122

  Human Necessities · mapped topic

• A61M1/1086 Primary

  Human Necessities · mapped topic

• A61M1/1046

  Human Necessities · mapped topic

• A61M60/411 Primary

  generated by an electromotor · CPC title

• A61M60/569

  synchronous with the native heart beat · CPC title