Method and apparatus for discrimination of monomorphic and polymorphic arrhythmias and for treatment thereof
First Claim
1. In a cardioverter/defibrillator of the type comprising treatment means for delivering a first therapy to a patient'"'"'s heart to treat tachycardia and a second therapy to said patient'"'"'s heart to treat fibrillation in response to criteria for discriminating tachycardia from fibrillation, a method of assisting the discrimination between tachycardia and fibrillation through a comparison of the degree of morphology of a series of cardiac electrical signals associated with cardiac depolarizations comprising the steps of:
- sensing electrical signals from said patient'"'"'s heart accompanying the depolarization of a chamber or chambers of said patient'"'"'s heart as the electrical signals successively appear;
successively sampling, processing and temporarily storing the sensed electrical signals as sets of wave shape amplitude data values of the sensed electrical signals;
successively determining the sampled point at which the sensed electrical signal meets predetermined sense detect criteria and for issuing a fiducial point signal indicative thereof;
successively selecting sub-sets of the sets of the processed and stored wave shape data referenced to the fiducial point signal, the sub-sets of wave shape data of a series of data sets being consistently selected with respect to the fiducial point signal so the selected sub-sets of data are consistent in number and sample point position with respect to each fiducial point signal;
successively positionally aligning the fiducial point signals of a series of subsets of wave shape data to positionally align the series of wave shape sub-set data;
first, comparing the values of the aligned data of at least two successive selected sub-sets of the processed and stored wave shape data to derive a like numbered sub-set of morphology difference data;
summing the sub-set of morphology difference data to provide a sampled morphology index value;
providing a threshold morphology index value which, if exceeded is indicative of the onset of polymorphic cardiac rhythm indicative of fibrillation; and
second, comparing the sampled morphology index value to the threshold morphology index value and generating a tachycardia or a fibrillation discrimination signal for use in confirming tachycardia or fibrillation and for selecting the appropriate therapy.
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Accused Products
Abstract
An implantable cardioverter/defibrillator system provided with method and apparatus for discrimination between monomorphic arrhythmias, e.g. ventricular tachycardia from polymorphic arrhythmias, e.g. ventricular fibrillation. A fiducial point of each successive QRS complex is detected prompting the storage of sampled and digitized waveform data within a timing window bridging the point in time of fiducial point detection. Stored sets of such sampled wave shape data are compared data point to data point resulting in a sampled morphology index value for each compared set. The magnitude of the sampled morphology index value or a series such index values are analyzed to determine the presence of a single or a progression of beat-to-beat waveform changes indicative of a polymorphic single transition or progression of QRS complexes from monomorphic to polymorphic waveforms indicative of an arrhythmia that should be treated with aggressive cardioversion/defibrillation therapies. The system is preferably provided with a closely spaced and widely spaced pairs of electrodes for sensing each QRS complex of the patient'"'"'s electrocardiogram. The closely spaced electrode pair is coupled to sense detect circuitry for identifying a predetermined fiducial point in the electrical signal associated with a ventricular depolarization and to counting and comparison circuitry for developing rate and onset data. The widely spaced pair of electrodes is coupled to sense and digitizing circuitry for developing the sampled waveform amplitude data from which the morphology index values are derived.
429 Citations
43 Claims
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1. In a cardioverter/defibrillator of the type comprising treatment means for delivering a first therapy to a patient'"'"'s heart to treat tachycardia and a second therapy to said patient'"'"'s heart to treat fibrillation in response to criteria for discriminating tachycardia from fibrillation, a method of assisting the discrimination between tachycardia and fibrillation through a comparison of the degree of morphology of a series of cardiac electrical signals associated with cardiac depolarizations comprising the steps of:
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sensing electrical signals from said patient'"'"'s heart accompanying the depolarization of a chamber or chambers of said patient'"'"'s heart as the electrical signals successively appear; successively sampling, processing and temporarily storing the sensed electrical signals as sets of wave shape amplitude data values of the sensed electrical signals; successively determining the sampled point at which the sensed electrical signal meets predetermined sense detect criteria and for issuing a fiducial point signal indicative thereof; successively selecting sub-sets of the sets of the processed and stored wave shape data referenced to the fiducial point signal, the sub-sets of wave shape data of a series of data sets being consistently selected with respect to the fiducial point signal so the selected sub-sets of data are consistent in number and sample point position with respect to each fiducial point signal; successively positionally aligning the fiducial point signals of a series of subsets of wave shape data to positionally align the series of wave shape sub-set data; first, comparing the values of the aligned data of at least two successive selected sub-sets of the processed and stored wave shape data to derive a like numbered sub-set of morphology difference data; summing the sub-set of morphology difference data to provide a sampled morphology index value; providing a threshold morphology index value which, if exceeded is indicative of the onset of polymorphic cardiac rhythm indicative of fibrillation; and second, comparing the sampled morphology index value to the threshold morphology index value and generating a tachycardia or a fibrillation discrimination signal for use in confirming tachycardia or fibrillation and for selecting the appropriate therapy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a cardioverter/defibrillator of the type comprising treatment means for delivering a first therapy to a patient'"'"'s heart to treat tachycardia and a second therapy to said patient'"'"'s heart to treat fibrillation in response to criteria for discriminating tachycardia from fibrillation, a apparatus for assisting the discrimination between tachycardia and fibrillation through a comparison of the degree of morphology of a series of cardiac electrical signals associated with cardiac depolarizations comprising:
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means for sensing electrical signals from said patient'"'"'s heart accompanying the depolarization of a chamber or chambers of said patient'"'"'s heart as the electrical signals successively appear; means for successively sampling, processing and temporarily storing the sensed electrical signals as sets of wave shape data representative of a like numbered set of wave shape amplitude values of the sensed electrical signals; means for successively determining the sample point at which the sensed electrical signal meets predetermined sense detect criteria and for issuing a fiducial point signal indicative thereof; means for successively selecting sub-sets of the sets of the processed and stored wave shape data referenced to the fiducial point signal, the sub-sets of wave shape data of a series of data sets being consistently selected with respect to the fiducial point signal so the selected sub-sets of data are consistent in number and sample point position with respect to each fiducial point signal; means for successively positionally aligning the fiducial point signals of a series of sub-sets of wave shape data to positionally align the series of wave shape sub-set data; first means for comparing the values of the aligned data of at least two successive selected sub-sets of the processed and stored wave shape data to derive a like numbered sub-set of morphology difference data; means for summing the sub-set of morphology difference data to provide a sampled morphology index value;
means for providing a threshold morphology index value which, if exceeded is indicative of the onset of polymorphic cardiac rhythm indicative of fibrillation; andsecond means for comparing the sampled morphology index value to the threshold morphology index value and generating a tachycardia or a fibrillation discrimination signal for use in confirming tachycardia or fibrillation and for selecting the appropriate therapy. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. In a cardioverter/defibrillator of the type comprising treatment means for delivering a first therapy to a patient'"'"'s heart to treat a monomorphic arrhythmia and a second therapy to said patient'"'"'s heart to treat a polymorphic arrhythmia in response to criteria for discriminating therebetween, a method of assisting the discrimination through a comparison of the degree of morphology of the far field electrogram associated with cardiac depolarizations recurring at a tachycardia rate comprising the steps of:
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providing a first pair of closely spaced electrodes in or adjacent to a chamber of a heart from which a near field electrogram may be detected; providing a second pair of widely spaced electrodes in or adjacent to a chamber of a heart from which a far field electrogram may be detected; sensing the near field waveform of the electrogram successively appearing across the first pair of electrodes and successively determining a fiducial point at which the sensed waveform amplitude value meets predetermined sense detect criteria and issuing a fiducial point signal indicative thereof; sensing the far field waveform of the electrogram successively appearing across the second pair of electrodes and providing a set of far field sampled amplitude data; aligning successive sets of far field sampled amplitude data positionally aligned to the near field fiducial point of each such data set; processing the values of the aligned successive sets of data to provide a sampled morphology index value; and
generating a tachycardia or a fibrillation discrimination signal as a function of the sampled morphology index value for use in confirming monomorphic tachycardia or polymorphic tachycardia or fibrillation and for selecting the appropriate therapy. - View Dependent Claims (32, 33, 34, 35, 36, 37)
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38. In a cardioverter/defibrillator of the type comprising treatment means for delivering a first therapy to a patient'"'"'s heart to treat a monomorphic arrhythmia and a second therapy to said patient'"'"'s heart to treat polymorphic arrhythmia in response to criteria for discriminating therebetween, apparatus for assisting the discrimination through a comparison of the degree of morphology of a series of cardiac electrical signals associated with cardiac depolarizations recurring at a tachycardia rate comprising:
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means for sensing near field and far field electrical signals from said patient'"'"'s heart accompanying the depolarization of a chamber or chambers of said patient'"'"'s heart as the electrical signals successively appear; means for sampling the far field electrical signals and for providing sets of waveform data representative of a like numbered set of wave shape amplitude values of the sensed far field electrical signals; means for successively determining a fiducial point at which the sensed near field electrical signal amplitude values meets predetermined sense detect criteria and for issuing a fiducial point signal indicative thereof; means for aligning successive sets of far field wave shape data positionally aligned with the fiducial point of each corresponding near field electrical signal; means for processing the values of the aligned data of at least two selected sub-sets of the stored far field wave shape data to provide a sampled morphology index value; means for providing a threshold morphology index value which, if exceeded is indicative of the onset of polymorphic cardiac rhythm indicative of fibrillation; and means for comparing the sampled morphology index value to the threshold morphology index value and generating a morphology discrimination signal for use in confirming monomorphic tachycardia or polymorphic tachycardia or fibrillation and for selecting the appropriate therapy. - View Dependent Claims (39, 40, 41, 42, 43)
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Specification