Detecting atrial fibrillation, method of and apparatus for

• US 20060195037A1
• Filed: 02/15/2006
• Published: 08/31/2006
• Est. Priority Date: 02/25/2005
• Status: Active Grant

• Current Assignee: Joseph Wiesel
• Original Assignee: Joseph Wiesel
• Inventors: Wiesel, Joseph
• Granted Patent: US 7,680,532 B2
• Time in Patent Office: Days
• US Class Current: 600/518
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• 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 5/1073 Measuring volume, e.g. of limbs
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61N 1/395 for treating atrial fibrillation

Abstract

A method and apparatus to determine possible atrial fibrillation or absence of atrial fibrillation that includes detecting pulse rhythms from a succession of time intervals each corresponding to a respective interval of time between successive pulse beats; analyzing the detected pulse rhythms to make a determination of possible atrial fibrillation; indicating the possible atrial fibrillation from the determination; or making a determination of the absence of atrial fibrillation.

Claims

1. A method of determining possible atrial fibrillation, said method comprising the steps of:

detecting a sequence of pulse beats to provide a succession of time intervals corresponding to the sequence of pulse beats;

ascertaining a mean of the succession of time intervals,

determining lower and upper boundary values each as a respective percent of the mean;

recalculating the mean and calculating a standard deviation based on the succession of time intervals that are at or between the upper and lower boundary values only without regard to those time intervals that may be less than the lower boundary value or higher than the upper boundary value, and

determining possible atrial fibrillation based upon a quotient formed by dividing the standard deviation by the recalculated mean and comparing the quotient with a threshold;

if the quotient exceeds the threshold value, the rhythm is atrial fibrillation.

3. The method of claim 1 where the said lower boundary level is in the range of about 0.50 to about 0.90 times the mean and the said upper boundary value is 1.1 to 1.5 times the mean.

4. The method of claim 1 wherein said threshold value is within the range of 0.01 to 0.10.

5. The method of claim 1, wherein the detecting is carried out by using either a sphygmomanometer or a plethysmograph.

2. A method of determining rhythms that are not atrial fibrillation, said method comprising the steps of:

detecting a sequence of pulse beats to provide a succession of time intervals corresponding to the sequence of pulse beats;

ascertaining a mean of the succession of time intervals;

determining lower and upper boundary values each as a respective percent of the said mean;

recalculating the mean and calculating a standard deviation based on the succession of time intervals that are at or between the upper and lower boundary values only without regard to those time intervals that may be less than the lower boundary value or higher than the upper boundary; and

determining possible atrial fibrillation based upon a quotient formed by dividing the standard deviation by the recalculated mean and comparing the quotient with a threshold;

if the quotient is less than the threshold value, the rhythm is not atrial fibrillation.

6. A method of determining possible atrial fibrillation, said method comprising the steps of:

sorting a sequence of pulse beat intervals by length from shortest to longest or longest to shortest;

determining N where N is the number of time intervals between successive pulse beats;

calculating an irregularity index I₁ for the first n time intervals, the irregularity index I₁ being a quotient of a mean and a standard deviation of a first n time intervals;

calculating an irregularity index I₂ for the n time intervals beginning with a second time interval, the irregularity index I₂ being a quotient of a mean and a standard deviation of n time intervals beginning with the second time interval; and

continuing to calculate an irregularity index I_m where m ranges from one until N−

(n−

1);

determining possible atrial fibrillation based on what percent, P, of the said irregularity indices I₁, I₂, . . . I<sub>N−

(n−

1)</sub>, are less than a threshold value T in that if P exceeds a cutoff value, P_cutoff, then the rhythm is considered to show an absence of atrial fibrillation, and If P is less than or equal to a cutoff value, P_cutoff, then the rhythm is considered atrial fibrillation.

7. The method of claim 6, wherein said threshold value T is within the range of about 0.01 to about 0.03.

8. The method of claim 6, wherein said cutoff value, P_cutoff, is within the range of 0.30 to 0.70.

9. An apparatus for determining possible atrial fibrillation, comprising:

a detector configured to detect irregular pulse rhythms from a succession of time intervals each corresponding to a respective interval of time between successive pulse beats of a sequence of the pulse beats;

a processor configured to analyze the detected irregular pulse rhythms for making a determination of possible atrial fibrillation;

the processor being configured to detect a plurality of pulse beats including the sequence of pulse beats using a sphygmomanometer or a plethysmograph; and

an indicator configured to indicate the possible atrial fibrillation based on the determination.

10. An apparatus to determine possible atrial fibrillation, comprising

means for ascertaining a mean of a succession of time intervals corresponding to that of a sequence of pulse beats;

means for determining lower and upper boundary values as a respective percent of the said mean;

means for recalculating a mean and calculating a standard deviation of the succession of time intervals that are at or between the lower and upper boundary values only without regard to those time intervals that may be less than the lower boundary value or higher than the upper boundary, and

means for determining possible atrial fibrillation based upon a quotient formed by dividing said standard deviation by said recalculated mean and comparing the quotient with a threshold value.

11. An apparatus of claim 10, further comprising detecting with a detector a sequence of pulse beats corresponding to the succession of pulse time intervals.

12. An apparatus to determine possible atrial fibrillation, comprising

means for sorting pulse beat intervals by length from shortest to longest or longest to shortest;

means for determining N where N is the number of time intervals between successive pulse beats;

means for calculating an irregularity index I₁ for the first n time intervals, the irregularity index I₁ being a quotient of a mean and a standard deviation of a first n time intervals;

means for calculating an irregularity index I₂ for the n time intervals beginning with the second time interval, the irregularity index I₂ being a quotient of a mean and a standard deviation of n time intervals beginning with the second time interval;

means for continuing to calculate an irregularity index I_m where m ranges from one until N−

(n−

1);

means for determining possible atrial fibrillation based on what percent, P, of the said irregularity indices I₁, I₂, . . . I<sub>N−

(n−

1)</sub>, are less than a threshold value T in that if P exceeds a cutoff value, P_cutoff, then the rhythm is not atrial fibrillation and If P is less than or equal to a cutoff value, P_cutoff, then the rhythm is atrial fibrillation.

13. A method for determining the absence of atrial fibrillation when there is a presence of abnormal pulse beats, said method comprising the steps of:

detecting an abnormal pulse rhythm from a succession of time intervals between pulse beats; and

analyzing with equipment the abnormal pulse rhythm to make a determination that the abnormal pulse rhythm is not an indication of atrial fibrillation.

14. An apparatus for determining the absence of atrial fibrillation when there is a presence of abnormal pulse beats comprising:

a detector to detect abnormal pulse rhythm from a succession of time intervals between pulse beats;

a processor configured to analyze the detected abnormal pulse rhythm for making a determination of an absence of atrial fibrillation; and

an indicator configured to indicate the absence of atrial fibrillation based on the determination.