Blending cardiac rhythm detection processes

Abstract

Systems and methods are described for classifying a cardiac rhythm. A cardiac rhythm is classified using a classification process that includes a plurality of cardiac rhythm discriminators. Each rhythm discriminator provides an independent classification of the cardiac rhythm. The classification process is modified if the modification is likely to produce enhanced classification results. The rhythm is reclassified using the modified classification process.

1 . A method to identify a tachyarrhythmia rhythm transition, the method comprising:
 monitoring a supraventricular tachyarrhythmia (SVT) rhythm from a first point in time to a second point in time, the SVT rhythm having at the first point in time, a first atrial-ventricular (A-V) relationship, a first indication of stability, and a first indication of correlation with a morphological template, and the SVT rhythm having at the second point in time, a second A-V relationship, a second indication of stability, and a second indication of correlation with the morphological template;   identifying whether there is a change in the A-V relationship from the first point in time to the second point in time, based on the first A-V relationship and the second A-V relationship;   identifying whether there is a change in the indication of stability from the first point in time to the second point in time, based on the first indication of stability and the second indication of stability;   identifying whether there is a change in the indication of correlation from the first point in time to the second point in time, based on the first indication of correlation and the second indication of correlation; and   identifying that a tachyarrhythmia rhythm transition from SVT is likely to exist based on whether there are changes in the A-V relationship, the indication of stability, or the indication of correlation from the first point in time to the second point in time.   
     
     
         2 . The method of  claim 1 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a supraventricular rhythm (SVR) template, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein identifying that the tachyarrhythmia rhythm transition from SVT is likely to exist comprises:
 reducing a template correlation threshold;   comparing the SVT rhythm with the SVR template using the template correlation threshold; and   when the SVT rhythm is not correlated with the SVR template, identifying that a tachyarrhythmia rhythm transition from SVT to ventricular tachyarrhythmia (VT) is likely to exist.   
     
     
         3 . The method of  claim 1 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a supraventricular rhythm (SVR) template, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein identifying that the tachyarrhythmia rhythm transition from SVT is likely to exist comprises:
 reducing a template correlation threshold;   comparing the SVT rhythm with the SVR template using the template correlation threshold; and   when the SVT rhythm is not correlated with the SVR template, identifying that a tachyarrhythmia rhythm transition from SVT to ventricular tachyarrhythmia (VT) is likely to exist.   
     
     
         4 . The method of  claim 3 , comprising using a rhythm identification process to confirm the transition to VT. 
     
     
         5 . The method of  claim 1 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A=V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein identifying that the tachyarrhythmia rhythm transition from SVT is likely to exist comprises:
 identifying that a rhythm transition has most likely not changed; and   confirming a status of the rhythm transition by calculating a correlation coefficient using a different template than the SVR template.   
     
     
         6 . The method of  claim 1 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A=V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein identifying that the tachyarrhythmia rhythm transition from SVT is likely to exist comprises:
 identifying that a rhythm transition has most likely not changed; and   confirming a status of the rhythm transition by calculating a correlation coefficient using an extended shift of feature points in a shock channel.   
     
     
         7 . The method of  claim 1 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein identifying that the tachyarrhythmia rhythm transition from SVT is likely to exist comprises:
 identifying that a rhythm transition has most likely transitioned to atrial fibrillation (AF); and   confirming a status of the rhythm transition by calculating a correlation coefficient using at least one of a different template than the SVR template or an extended shift of feature points in a shock channel.   
     
     
         8 . A non-transitory machine-readable medium comprising instructions to identify a tachyarrhythmia rhythm transition, which when executed by a machine, cause the machine to:
 monitor a supraventricular tachyarrhythmia (SVT) rhythm from a first point in time to a second point in time, the SVT rhythm having at the first point in time, a first atrial-ventricular (A-V) relationship, a first indication of stability, and a first indication of correlation with a morphological template, and the SVT rhythm having at the second point in time, a second A-V relationship, a second indication of stability, and a second indication of correlation with the morphological template;   identify whether there is a change in the A-V relationship from the first point in time to the second point in time, based on the first A-V relationship and the second A-V relationship;   identify whether there is a change in the indication of stability from the first point in time to the second point in time, based on the first indication of stability and the second indication of stability;   identify whether there is a change in the indication of correlation from the first point in time to the second point in time, based on the first indication of correlation and the second indication of correlation; and   identify that a tachyarrhythmia rhythm transition from SVT is likely to exist based on whether there are changes in the A-V relationship, the indication of stability, or the indication of correlation from the first point in time to the second point in time.   
     
     
         9 . The non-transitory machine-readable medium of  claim 8 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a supraventricular rhythm (SVR) template, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the instructions to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist comprise instructions to:
 reduce a template correlation threshold;   compare the SVT rhythm with the SVR template using the template correlation threshold; and   when the SVT rhythm is not correlated with the SVR template, identify that a tachyarrhythmia rhythm transition from SVT to ventricular tachyarrhythmia (VT) is likely to exist.   
     
     
         10 . The non-transitory machine-readable medium of  claim 8 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a supraventricular rhythm (SVR) template, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the instructions to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist comprise instructions to:
 reduce a template correlation threshold;   compare the SVT rhythm with the SVR template using the template correlation threshold; and   when the SVT rhythm is not correlated with the SVR template, identify that a tachyarrhythmia rhythm transition from SVT to ventricular tachyarrhythmia (VT) is likely to exist.   
     
     
         11 . The non-transitory machine-readable medium of  claim 10 , comprising instructions to use a rhythm identification process to confirm the transition to VT. 
     
     
         12 . The non-transitory machine-readable medium of  claim 8 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A=V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the instructions to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist comprise instructions to:
 identify that a rhythm transition has most likely not changed; and   confirm a status of the rhythm transition by calculating a correlation coefficient using a different template than the SVR template.   
     
     
         13 . The non-transitory machine-readable medium of  claim 8 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A=V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the instructions to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist comprise instructions to:
 identify that a rhythm transition has most likely not changed; and   confirm a status of the rhythm transition by calculating a correlation coefficient using an extended shift of feature points in a shock channel.   
     
     
         14 . The non-transitory machine-readable medium of  claim 8 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the instructions to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist comprise instructions to:
 identify that a rhythm transition has most likely transitioned to atrial fibrillation (AF); and   confirm a status of the rhythm transition by calculating a correlation coefficient using at least one of a different template than the SVR template or an extended shift of feature points in a shock channel.   
     
     
         15 . A tachyarrhythmia detection and classification system, comprising:
 a sensing circuit, adapted to sense at least one cardiac signal; and   an implant controller, coupled to the sensing circuit, the implant controller including:
 an arrhythmia discriminator module, the arrhythmia discriminator module adapted to: 
 monitor a supraventricular tachyarrhythmia (SVT) rhythm from a first point in time to a second point in time, the SVT rhythm having at the first point in time, a first atrial-ventricular (A-V) relationship, a first indication of stability, and a first indication of correlation with a morphological template, and the SVT rhythm having at the second point in time, a second A-V relationship, a second indication of stability, and a second indication of correlation with the morphological template; 
 identify whether there is a change in the A-V relationship from the first point in time to the second point in time, based on the first A-V relationship and the second A-V relationship; 
 identify whether there is a change in the indication of stability from the first point in time to the second point in time, based on the first indication of stability and the second indication of stability; 
 identify whether there is a change in the indication of correlation from the first point in time to the second point in time, based on the first indication of correlation and the second indication of correlation; and 
 identify that a tachyarrhythmia rhythm transition from SVT is likely to exist based on whether there are changes in the A-V relationship, the indication of stability, or the indication of correlation from the first point in time to the second point in time. 
   
     
     
         16 . The system of  claim 15 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a supraventricular rhythm (SVR) template, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the arrhythmia discriminator module is adapted to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist by:
 reducing a template correlation threshold;   comparing the SVT rhythm with the SVR template using the template correlation threshold; and   when the SVT rhythm is not correlated with the SVR template, identifying that a tachyarrhythmia rhythm transition from SVT to ventricular tachyarrhythmia (VT) is likely to exist.   
     
     
         17 . The system of  claim 15 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a supraventricular rhythm (SVR) template, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the arrhythmia discriminator module is adapted to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist by:
 reducing a template correlation threshold;   comparing the SVT rhythm with the SVR template using the template correlation threshold; and   when the SVT rhythm is not correlated with the SVR template, identifying that a tachyarrhythmia rhythm transition from SVT to ventricular tachyarrhythmia (VT) is likely to exist.   
     
     
         18 . The system of  claim 17 , wherein the arrhythmia discriminator module is adapted to use a rhythm identification process to confirm the transition to VT. 
     
     
         19 . The system of  claim 15 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A=V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the arrhythmia discriminator module is adapted to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist by:
 identifying that a rhythm transition has most likely not changed; and   confirming a status of the rhythm transition by calculating a correlation coefficient using a different template than the SVR template.   
     
     
         20 . The system of  claim 15 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A=V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the arrhythmia discriminator module is adapted to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist by:
 identifying that a rhythm transition has most likely not changed; and   confirming a status of the rhythm transition by calculating a correlation coefficient using an extended shift of feature points in a shock channel.   
     
     
         21 . The system of  claim 15 , wherein the first A-V relationship is A=V or A>V, and the first indication of correlation indicates that the SVT rhythm is correlated to a SVR template, and the first indication of stability indicates that the SVT rhythm is unstable, and wherein the second A-V relationship is A>V, and the second indication of correlation indicates that the SVT rhythm is uncorrelated to the SVR template, and wherein the arrhythmia discriminator module is adapted to identify that the tachyarrhythmia rhythm transition from SVT is likely to exist by:
 identifying that a rhythm transition has most likely transitioned to atrial fibrillation (AF); and   confirming a status of the rhythm transition by calculating a correlation coefficient using at least one of a different template than the SVR template or an extended shift of feature points in a shock channel.