Method and system of automated hemodynamical detection of arrhythmias

• US 20010034488A1
• Filed: 02/05/2001
• Published: 10/25/2001
• Est. Priority Date: 02/09/2000
• Status: Abandoned Application

• Current Assignee: Impulse Dynamics NV
• Original Assignee: Impulse Dynamics NV
• Inventors: Policker, Shal, Mika, Yuval, Shemer, Itzhak, Harel, Tamar
• Application Number:
  US09/776,632
• Publication Number:
  US 20010034488A1
• Time in Patent Office: Days
• US Class Current: 600/515
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

A method for automated detection of arrhythmias in a patient is disclosed, said method comprising:

obtaining continuous pressure data from a cardiac chamber of said patient;

segmenting said pressure data to correspond to beat segments;

extracting features from each of said beat segments with respect to a predetermined number of earlier beat segments, said features relating to at least some of the criteria selected from: beat-to-beat change in the duration of said beat segments, beat-to-beat change in the peak to-peak amplitude of said beat segments, beat-to-boat change in heart rate of said patient and change in value and instance in time of max dP/dt, where P is pressure and t is time; and

classifying each of said beat segments as ectopic or normal, wherein ectopic beat is determined using a set of predetermined rules aimed at detecting abnormality in features of each of said beat segments with reference to predetermined thresholds.

Claims

1. A method for automated detection of arrhythmias in a patient said method comprising:

obtaining a hemodynamic data signal corresponding to a continuous pressure data from a cardiac chamber of said patient;

segmenting said pressure data to correspond to beat segments;

extracting hemodynamic features from each of said beat segments with respect to a predetermined number of earlier beat segments, said hemodynamic features relating to the hemodynamic data signal, and

classifying each of said beat segments as ectopic or normal wherein ectopic beat is determined using a set of predetermined rules aimed at detecting abnormality in features of each of said beat segments with reference to predetermined thresholds.

2. The method as claimed in

claim 1

, wherein the hemodynamic features correspond to at least some of the criteria selected from. beat-to-beat change in the duration of said beat segments, beat-to-beat change in the peak-to-peak amplitude of said beat segments, beat-to-beat change in heart rate of said patient as measured in the time difference between two instances of max dP/dt of each two consecutive beats and change in value and instance in time of max dP/dt, where P is pressure and t is time.

3. The method as claimed in

claim 2

, wherein said max dP/dt is calculated as the first derivative of sub-segments of the pressure beat segment, after smoothing of the beat.

4. The method as claimed in

claim 3

, wherein said smoothing is done using Savitzki-Golay filtering.

5. The method as claimed in

claim 1

, wherein a beat segment is classified as ectopic when a deviation of not less than 10% from norm hemodynamic values is detected.

6. The method as claimed in

claim 1

wherein the obtaining of continuous pressure data from a cardiac chamber of said patient comprises positioning a pressure sensor within a cardiac chamber of the patient, and reading continuous pressure data by a reader electrically connected to the pressure sensor.

7. The Method as claimed in

claim 1

, wherein said segmenting said pressure reading to correspond to beats segments comprises determining adaptive zero crossing.

8. The method as claimed in

claim 1

, wherein said segmenting said pressure reading to correspond to beats segments comprises,

estimating of the DC offset of said beats;

and

subtracting the estimated DC offset from said beat to find two zero crossing points.

9. The method as claimed in

claim 8

, wherein said estimating of the DC offset of said beats comprises:

marking all local maximas within the segment and above a predetermined first threshold value;

choosing a point which is the lowest among all local maxima;

marking all local minimas within the segment and below a predetermined second threshold value;

choosing a point which is the highest among all local minima; and

calculating the DC offset as the average value between the lowest local maximum and highest local minimum.

10. The method as claimed in

claim 9

, wherein said first threshold value is in the range of 20-30 mmHg.

11. The method as claimed in

claim 9

, wherein said second threshold value is in the range of 30-40 mmHg.

12. The method as claimed in

claim 8

further comprising:

determining whether the time lapsed between each pair of adjacent zero crossing points is not less then 40 msec; and

excluding the pair of zero crossing point that occurred less then 40 msec from previous pair of zero crossing points.

13. The method as claimed in

claim 1

, wherein one hemodynaic feature relates to a norm value that corresponds to the end systolic pressure value defined as the highest value of the pressure data.

14. The method as claimed in

claim 13

, wherein the end systolic pressure is determined by:

finding the minimal absolute derivative in the range of the maximum pressure beat;

determining the maximum of the beat;

centering a window of about 50 msec centered about said maximum beat; and

calculating the smoothed absolute first derivative in the range of said window, and determining the end systolic pressure as the minimum value.

15. The method as claimed in

claim 14

, wherein said peak-to-peak amplitude is calculated by subtracting the lowest plateau pressure value of the beat from the end systolic pressure value.

16. A system for the automated detection of arrhythmias in a patient, said system comprising:

a pressure sensor adapted to be positioned within a patient'"'"'s cardiac chamber;

a processor communicating with said pressure sensor, said processor to adapted to obtain continuous pressure data from said pressure sensor, segment said pressure data to correspond to beat segments, extract features from each of said beat segments with respect to a predetermined number of earlier beat segments, said features relating to at least some of the criteria selected from;

beat-to-beat change in the duration of said beat segments, beat-to-beat change in the peak-to-peak amplitude of said beat segments, beat-to-beat change in heart rate of said patient and change in value and instance in time of max dP/dt, where P is pressure and t is time, and classify each of said beat segments as ectopic or normal, wherein ectopic beat is determined using a set of predetermined rules aimed at detecting abnormality in features of each of said beat segments with reference to predetermined thresholds.