Heart beat identification and pump speed synchronization
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.
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 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 .
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 =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 .
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 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 .
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 =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 .
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.