Heart beat identification and pump speed synchronization

• US 10,052,420 B2
• Filed: 02/11/2016
• Issued: 08/21/2018
• Est. Priority Date: 04/30/2013
• Status: Active Grant

• Current Assignee: TC1 LLC (Abbott Laboratories Incorporated)
• Original Assignee: TC1 LLC (Abbott Laboratories Incorporated)
• Inventors: Medvedev, Alexander, Yu, Shunzhou, You, Ren
• Primary Examiner(s): Holmes, Rex R
• Application Number:
  US15/041,716
• Publication Number:
  US 20160228628A1
• Time in Patent Office: 922 Days
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/216 including a rotating member acting on the blood, e.g. impeller
• CPC Class Codes: A61M 60/411 generated by an electromotor
• CPC Class Codes: A61M 60/515 Regulation using real-time patient data
• CPC Class Codes: A61M 60/569 synchronous with the native heart beat

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.

Claims

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 the 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, 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; 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 the patient'"'"'s cardiac cycle.

2. The method for synchronizing operation of the heart assist pump device to the 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 the heart assist pump device to the 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 the heart assist pump device to the patient'"'"'s cardiac cycle of claim 1, wherein determining whether a pulse is complete comprises:

determining that Diff_max2Mean[i] is (1) greater than a first product of c₁ and Diff_max2Min[i]; and

(2) is lesser than a second product of c₂ 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}.

5. The method for synchronizing operation of the heart assist pump device to the patient'"'"'s cardiac cycle of claim 1, wherein the determining a pulse period comprises:

determining the median of T_f2f[i], T_r2r[i], T_min2min[i], and T_max2max[i].

6. The method for synchronizing operation of the heart assist pump device to the 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=k₁T_min2max, and k₁≈

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=k₁T_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=k₂T_min2max, and k₂≈

0.125 to 0.3, which depends on the T_sp.

7. The method for synchronizing operation of the heart assist pump device to the 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.

8. The method for synchronizing operation of the heart assist pump device to the 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.

9. The method for synchronizing operation of the heart assist pump device to the 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.

10. 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, 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; 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.

11. The heart assist pump device of claim 10, wherein obtaining frequency range data comprises:

filtering out data that is not less than about 5 Hz.

12. The heart assist pump device of claim 11, wherein filtering out data comprises:

employing one or both of a finite impulse response filter and an infinite impulse response filter.

13. The heart assist pump device of claim 10, wherein determining whether a pulse is complete comprises:

determining that Diff_max2Mean[i] is (1) greater than a first product of c₁ and Diff_max2Min[i]; and

(2) is lesser than a second product of c₂ 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}.

14. The heart assist pump device of claim 10, wherein determining the pulse period comprises:

determining the median of T_f2f[i], T_r2r[i], T_min2min[i], and T_max2max[i].

15. The heart assist pump device of claim 10, 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=k₁T_min2max, and k₁≈

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=k₁T_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=k₂T_min2max, and k₂≈

0.125 to 0.3, which depends on the T_sp.

16. The heart assist pump device of claim 10, 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[j]=t_sync[0]−

T_offset+(j−

1)*T_cyc[i], where T_offset<

T_min2max and T_offset≈

40˜

80 ms.

17. The heart assist pump device of claim 10, wherein the modulation of the speed of the motor comprises:

an increase in the speed of the motor that corresponds to an increase in a rate of the cardiac cycle.

18. The heart assist pump device of claim 10, wherein the frequency range data comprises:

one or both of motor current data and motor power signal data.

19. A non-transitory machine readable medium having instructions stored thereon for synchronizing operation of a heart assist pump device to a patient'"'"'s cardiac cycle, wherein the instructions are executable by one or more processors to at least:

obtain a signal from a motor of the heart assist pump device;

filter the signal to remove noise;

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 filtered signal, 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; and

modulate 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 the patient'"'"'s cardiac cycle.

20. The non-transitory machine readable medium of claim 19, wherein the signal comprises:

a current signal or a power signal.