Method of estimating heart rate and detecting tachyarrhythmia

1. A method of estimating a heart rate of a patient having an implantable blood pump comprising:

during operation of the blood pump:

continuously detecting a plurality of cardiac cycles, each of the plurality of cardiac cycles including a length;

sorting the plurality of cardiac cycles according to the length;

filtering the plurality of cardiac cycles between one of a group consisting of including a reliable condition and at least one unreliable condition;

continuously estimating a heart rate according to the length of the plurality of cardiac cycles and the reliable condition;

calculating a pulsatility of the estimated heart rate over a predetermined time interval;

comparing the calculated pulsatility to a predetermined threshold;

determining whether the at least one condition includes low pulsatility based on the comparison of the calculated pulsatility and the predetermined threshold; and

if the at least one unreliable condition is detected, modifying the estimated heart rate based on the detected at least one unreliable condition.

2. The method of claim 1 , wherein the at least one unreliable condition includes an individual heart rate estimate.

3. The method of claim 1 , wherein the unreliable condition further includes one selected from the group consisting of the plurality of cardiac cycles including a length deviating from a standard length, and a tachyarrhythmia.

4. The method of claim 3 , further comprising generating a low pulsatility alert when the unreliable condition is the low pulsatility, and, during a duration of the low pulsatility alert, automatically excluding the plurality of cardiac cycles from the heart rate estimating.

5. The method of claim 4 , wherein the plurality of cardiac cycles define a buffer, and the buffer is reset when the duration of the low pulsatility alert continues for a predetermined duration.

6. The method of claim 1 , further comprising:

defining a running average of a beat-to-beat difference in a pair of adjacent cardiac cycles of the plurality of cardiac cycles; and

classifying at least one of the plurality of cardiac cycles as including the unreliable condition when the running average is greater than a predetermined percentage of a predetermined average.

7. The method of claim 1 , further comprising detecting and maintaining an R-R expected range.

8. The method of claim 1 , wherein the plurality of cardiac cycles define a buffer, and the buffer is continuously maintained using a most recent plurality of cardiac cycles.

9. A system of estimating a heart rate of a patient comprising:

an implantable blood pump;

a controller in communication with the implantable blood pump and including a processor, the processor being configured to:

during operation of the blood pump:

continuously detect a plurality of cardiac cycles, each of the plurality of cardiac cycles including a length;

sort the plurality of cardiac cycles according to the length;

filter the plurality of cardiac cycles between one of a group consisting of including a reliable condition and at least one unreliable condition;

continuously estimate a heart rate according to the length of the plurality of cardiac cycles and the reliable condition;

calculating a pulsatility of the estimated heart rate over a predetermined time interval;

comparing the calculated pulsatility to a predetermined threshold;

determining whether the at least one condition includes low pulsatility based on the comparison of the calculated pulsatility and the predetermined threshold; and

if the at least one unreliable condition is detected, modify the estimated heart rate based on information associated with the detected at least one unreliable condition.