Method and apparatus for determining a heart period from an ecg waveform using image representation of ecg

Abstract

A method and system and computer program product for estimating a heart period is disclosed. The heart period is detected from an ECG recording. ECG data is acquired, and converted into electronic ECG images. The data is processed to prepare for estimation of a heart period. The heart period is estimated based upon an average of intervals between a plurality of detected peaks of electronic electrocardiogram waveforms. The peaks are determined by taking a product of a filtered electronic ECG signal with a wandering baseline removed, a difference between the upper and lower ECG envelopes of the electronic ECG images, and a first order derivative of a derived ECG waveform.

1 . A method for estimating a heart period using at least one of a plurality of electrocardiogram recordings, comprising:
 utilizing a computer processor to convert a plurality of the electrocardiogram recordings into a plurality of corresponding electronic electrocardiogram images;   deriving an electrocardiogram waveform from one of the electronic electrocardiogram images by extracting an upper envelope and a lower envelope of the electrocardiogram waveform from the corresponding electronic electrocardiogram image using a curve tracing algorithm;   determining an electrocardiogram signal peak from increased thickness at the electrocardiogram signal peak due to pixel dithering;   determining a difference between the upper envelope and the lower envelope at the electrocardiogram signal peak and at an electrocardiogram low point, which are a local maximum and a local minimum of one of the corresponding electronic electrocardiogram images; and   estimating the heart period.   
     
     
         2 . The method of  claim 1 , wherein the algorithm for extracting the upper envelope and lower envelope comprises:
 tracing upper and lower edges of a curve of the electrocardiogram waveform from one of the electronic electrocardiogram images;   defining two search ranges centered around the upper and lower edges of the curve of the electrocardiogram waveform;   using at least one of: a morphological open algorithm to fill in holes inside the curve of the electrocardiogram waveform and   a morphological close algorithm to eliminate noise pixels near the curve of the electrocardiogram waveform;   closing small gaps by closing the electrocardiogram waveform between inserted seed points along an expected location of the derived electrocardiogram waveform; and   closing large gaps by inserting a segment tangent to the curve of the electrocardiogram waveform.   
     
     
         3 . The method of  claim 2 , wherein estimating the heart period comprises:
 computing a first order derivative of the derived electrocardiogram waveform for amplifying high frequencies of the derived electrocardiogram waveform;   determining a peak of the derived electrocardiogram waveform by taking a product of a filtered electrocardiogram signal from one of the corresponding electronic electrocardiogram images, with a wandering baseline removed, a difference between the upper envelope and the lower envelope of the derived electrocardiogram waveform from each of the at least one of the corresponding electronic electrocardiogram images and the first order derivative of the derived electrocardiogram waveform; and   determining an average of intervals between a plurality of detected peaks of the electrocardiogram waveform from at least one region selected from the electronic electrocardiogram image.   
     
     
         4 . The method of  claim 3 , further comprising obtaining the plurality of electrocardiogram recordings generated from a plurality of electrocardiogram sources. 
     
     
         5 . The method of  claim 4 , further comprising removing noise from the corresponding electronic electrocardiogram images. 
     
     
         6 . The method of  claim 5 , further comprising outputting the determined heart period on a display. 
     
     
         7 . The method of  claim 6 , wherein at least one of the electrocardiogram sources comprises a paper form electrocardiogram source. 
     
     
         8 . The method of  claim 7 , further comprising scanning the paper form of said electrocardiogram source into at least one electronic electrocardiogram image. 
     
     
         9 . The method of  claim 6 , wherein at least one of the electrocardiogram sources comprises a digital form electrocardiogram source. 
     
     
         10 . The method of  claim 6 , wherein at least one of the electrocardiogram sources comprises an echocardiogram from an echocardiogram source. 
     
     
         11 . A system for estimating a heart period using at least one of a plurality of electrocardiogram recordings, comprising:
 a conversion machine for converting an at least one electrocardiogram recording into a corresponding electronic electrocardiogram image;   a derivation machine for:
 deriving an electrocardiogram waveform from the corresponding electronic electrocardiogram image, by extracting an upper envelope and a lower envelope of the derived electrocardiogram waveform from the electronic electrocardiogram image using a curve tracing algorithm; 
 determining an electrocardiogram signal peak from increased thickness at the electrocardiogram signal peak due to pixel dithering; and 
 determining the difference between the upper envelope and the lower envelope at the electrocardiogram signal peak and at an electrocardiogram low point, which are a local maximum and a local minimum of the derived electrocardiogram waveform from the corresponding electronic electrocardiogram image; and 
   an estimation machine for:
 computing a first order derivative of the derived electrocardiogram waveform for amplifying high frequencies of the derived electrocardiogram waveform; 
 determining a peak of the derived electrocardiogram waveform by taking a product of a filtered electrocardiogram signal from the corresponding electronic electrocardiogram image in which a wandering baseline has been removed, a difference between the upper envelope and the lower envelope of the derived electrocardiogram waveform in the corresponding electronic electrocardiogram image and the first order derivative of the derived electrocardiogram waveform; and 
 estimating the heart period as an average of intervals between a plurality of detected peaks from the at least one simultaneously selected region from each of the plurality of electronic electrocardiogram images and from the derived electrocardiogram waveform. 
   
     
     
         12 . The system of  claim 11 , wherein the algorithm for extracting the upper envelope and lower envelope comprises:
 tracing upper and lower edges of a curve of the electrocardiogram waveform from one of the electronic electrocardiogram images;   defining two search ranges centered around the upper and lower edges of the curve of the electrocardiogram waveform;   using at least one of: a morphological open algorithm to fill in holes inside the curve of the electrocardiogram waveform and   a morphological close algorithm to eliminate noise pixels near the curve of the electrocardiogram waveform;   closing small gaps by closing the electrocardiogram waveform between inserted seed points along an expected location of the derived electrocardiogram waveform; and   closing large gaps by inserting a segment tangent to the curve of the electrocardiogram waveform.   
     
     
         13 . The system of  claim 12 , further comprising an electrocardiogram machine coupled to the conversion machine and utilizing a computer processor to obtain at least one of the plurality of electrocardiogram recordings generated from at least one of a plurality electrocardiogram sources. 
     
     
         14 . The system of  claim 13 , further comprising a de-noising machine coupled to the conversion machine and for removing noise from the corresponding electronic electrocardiogram image. 
     
     
         15 . The system of  claim 14 , further comprising a display coupled to the estimation machine and for outputting the estimated heart period. 
     
     
         16 . The system of  claim 15 , wherein at least one of the electrocardiogram sources comprises a paper form electrocardiogram source. 
     
     
         17 . The system of  claim 15 , wherein at least one of the electrocardiogram sources comprises a digital form electrocardiogram source. 
     
     
         18 . The system of  claim 15 , wherein at least one of the electrocardiogram sources comprises an echocardiogram from an echocardiogram source. 
     
     
         19 . The system of  claim 16 , wherein the conversion machine scans the paper form electrocardiogram source into at least one electronic electrocardiogram image. 
     
     
         20 . A processor implemented computer program product for estimating a heart period using at least one of a plurality of electrocardiogram recordings, comprising:
 computer program code performing on a computer processor in an electrocardiogram machine measuring electrical activity of a heart for:
 obtaining at least one of a plurality of electrocardiogram recordings generated from at least one of a plurality of electrocardiogram sources; 
 converting at least one electrocardiogram recording into a corresponding electronic electrocardiogram image; 
 removing noise from the corresponding electronic electrocardiogram image; 
   deriving an electrocardiogram waveform from the corresponding electronic electrocardiogram image, by extracting an upper envelope and a lower envelope of the derived electrocardiogram waveform from the electronic electrocardiogram image using a curve tracing algorithm, the algorithm for extracting the upper envelope and lower envelope comprising:
 tracing upper and lower edges of a curve of the electrocardiogram waveform from the corresponding electronic electrocardiogram image; 
 defining two search ranges centered around the upper and lower edges of the curve of the electrocardiogram waveform; 
 using a morphological open algorithm to fill in holes inside the curve of the electrocardiogram waveform; 
 using a morphological close algorithm to eliminate noise pixels near the curve of the electrocardiogram waveform; 
 closing small gaps by closing the derived electrocardiogram waveform between inserted seed points along an expected location of the electrocardiogram waveform; and 
 closing large gaps by inserting a segment tangent to the curve of the electrocardiogram waveform; and 
 determining an electrocardiogram signal peak from increased thickness at the electrocardiogram signal peak due to pixel dithering; 
   determining a difference between the upper envelope and the lower envelope at the electrocardiogram signal peak and at an electrocardiogram low point which are a local maximum and a local minimum of the derived electrocardiogram waveform from the corresponding electronic electrocardiogram image;   estimating the heart period, by
 computing a first order derivative of the derived electrocardiogram waveform for amplifying high frequencies of the derived electrocardiogram waveform; 
 determining a peak of the derived electrocardiogram waveform by taking a product of a filtered electrocardiogram signal from the corresponding electronic electrocardiogram image with a wandering baseline removed, the difference between the upper envelope and the lower envelope of the derived electrocardiogram waveform in the corresponding electronic electrocardiogram image, and the first order derivative of the derived electrocardiogram waveform; and 
 estimating the heart period, as an average of intervals between a plurality of detected peaks from the derived electrocardiogram waveform; and 
   outputting the estimated heart period on a user interface display.