Method for determining dominant heart rates

• US 5,357,970 A
• Filed: 04/08/1993
• Issued: 10/25/1994
• Est. Priority Date: 04/08/1993
• Status: Expired due to Fees

• Current Assignee: Critikon Co. LLC (GE Aerospace)
• Original Assignee: Critikon, Inc. (Johnson & Johnson)
• Inventors: Browne, David W.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US08/044,969
• Time in Patent Office: 565 Days
• Field of Search: 128/696, 128/706, 128/698, 364/413.06, 364/413.03, 364/413.05
• US Class Current: 600/519
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient

Abstract

A method for determining a dominant heart rate from a series of beat triggers representative of a mixed series of normal heart beats and non-arrhythmic activities, with the beat triggers being determined at a specific sampling rate defining sample intervals, comprising the steps of: framing a window to include a portion of the series of beat triggers and to be beat-aligned with a first beat trigger and a last beat trigger, the window thereby defining a plurality of trigger intervals for respective adjacent beat triggers, with each trigger interval containing a plurality of the sample intervals existing between the respective adjacent beat triggers; summing the windowed sample intervals; for each of the trigger intervals, computing a weight factor based upon the ratio of the summed windowed sample intervals to the number of sample intervals within that trigger interval; grouping the trigger intervals according to the weight factors; computing the percentage of the window that each group of weight factors constitutes to determine the dominant group containing the dominant beat triggers; and analyzing the dominant beat triggers within the dominant group to determine the dominant heart rate.

Claims

1. A method for determining a dominant heart rate from a series of beat triggers representative of a mixed series of normal heart beats and non-arrhythmic activities, with the beat triggers being determined at a specific sampling rate defining sample intervals, comprising the steps of:

framing a window to include a portion of the series of beat triggers and to be beat-aligned with a first beat trigger and a last beat trigger, the window thereby defining a plurality of trigger intervals for respective adjacent beat triggers, with each trigger interval containing a plurality of the sample intervals existing between the respective adjacent beat triggers;

summing the windowed sample intervals;

for each of the trigger intervals, computing a weight factor based upon the ratio of the summed windowed sample intervals to the number of sample intervals within that trigger interval;

grouping the trigger intervals according to the weight factors;

computing the percentage of the window that each group of weight factors constitutes to determine the dominant group containing the dominant beat triggers; and

analyzing the dominant beat triggers within the dominant group to determine the dominant heart rate.

2. The method as set forth in claim 1, wherein the step of framing a window to include a portion of the series of beat triggers and to be beat-aligned with a first beat trigger and a last beat trigger, comprises the step of sizing the window including the steps of aligning a leftmost frame of the window with the first beat trigger and aligning a rightmost frame of the window with the last beat trigger.

3. The method as set forth in claim 2, wherein the step of sizing the window comprises the step of predetermining a minimum-sized window, aligning the leftmost frame of the minimum-sized window with the first beat trigger and then increasing the rightmost frame of the minimum-sized window such that the rightmost frame of the window is aligned with the next beat trigger after the minimum-sized window.

4. The method as set forth in claim 1, wherein the steps of grouping the weight factors and computing the percentage of the window that each group of weight factors constitutes to determine the dominant group, comprise the step of:

numbering bins to correspond to the weight factors; and

computing the percentage of the window that each numbered bin represents to determine the dominant numbered bin containing the dominant beat triggers.

5. The method as set forth in claim 4, wherein the step of numbering bins to correspond to the weight factors, comprises the steps of determining the maximum number of sample intervals that occur for a maximum-anticipated heart rate at the specific sampling rate, computing the ratio of the number of windowed sample intervals to such maximum number of sample intervals, numbering the maximum numbered bin to the closest whole number to the ratio, and then evenly distributing the groups of weight factors in increasing order from numbered bin one to the maximum numbered bin.

6. The method as set forth in claim 5, wherein the sampling rate is approximately 400 hertz and wherein the minimum-sized window comprises approximately five seconds.

7. The method as set forth in claim 6, wherein the step of numbering bins to respective increasing bin numbers, comprises the step of numbering bins to substantially a range of 1-29.

8. The method as set forth in claim 4, wherein the step of computing the percentage of the window that each numbered bin represents to determine the dominant numbered bin containing the dominant beat triggers, comprises, for each numbered bin, the step of determining the number of trigger intervals contained within that numbered bin and then dividing that number of trigger intervals by that numbered bin'"'"'s bin number to compute the percentage of the window that that numbered bin represents.

9. The method as set forth in claim 8, wherein the step of computing the percentage of the window that each numbered bin represents to determine which numbered bin contains the dominant beat triggers, further comprises the step of selecting the numbered bins constituting the highest percentages of the window as the dominant numbered bins containing the dominant beat triggers.

10. The method as set forth in claim 9, wherein the step of analyzing the beat triggers within the dominant numbered bins to determine the dominant heart rate comprises the step of averaging the dominant beat triggers within the dominant numbered bins to compute the dominant heart rate.

11. The method as set forth in claim 8, wherein the step of analyzing the beat triggers within the dominant numbered bins to determine the dominant heart rate comprises the step of selecting the most dominant bin constituting the highest percentage.

12. The method as set forth in claim 1, wherein the step of analyzing the beat triggers within the dominant group to determine the dominant heart rate comprises the step of averaging the dominant beat triggers within the most dominant group to compute the most dominant heart rate.