DISCRIMINATION OF SUPRAVENTRICULAR TACHYCARDIA AND VENTRICULAR TACHYCARDIA EVENTS

• US 20110034817A1
• Filed: 10/11/2010
• Published: 02/10/2011
• Est. Priority Date: 03/12/1999
• Status: Active Grant

• Current Assignee: Alan F. Marcovecchio
• Original Assignee: Alan F. Marcovecchio
• Inventors: Marcovecchio, Alan F.
• Granted Patent: US 7,991,457 B2
• Time in Patent Office: Days
• US Class Current: 600/518
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

A method and system for discrimination of supraventricular tachycardia and ventricular tachycardia events. Morphological features points are extracted from normal sinus rhythm (NSR) complexes and used to generate a NSR template. A numerical convolution is performed using the NSR template and the feature points for each sensed NSR to give a NSR filter output. Using a plurality of NSR complexes, a median NSR filter output template is determined, where the median NSR filter output template has a median value for each value in the NSR filter output. The median NSR filter output template is then used during a tachycardia event to distinguish tachycardia events as either ventricular tachycardia events or supraventricular tachycardia events.

Claims

1. A method, comprising:

storing a normal sinus rhythm (NSR) output template;

sensing cardiac signals including tachycardia complexes;

extracting tachycardia feature points from the tachycardia complexes;

generating a tachycardia complex output using the NSR output template and the tachycardia feature points for each of the tachycardia complexes;

comparing the tachycardia complex output to the NSR output template; and

classifying the tachycardia complexes as either ventricular tachycardia (VT) complexes or supraventricular tachycardia (SVT) complexes using an outcome of the comparison of the tachycardia complex output to the NSR output template.

2. The method of claim 1, comprising:

determining whether a number of the tachycardia complexes classified as the VT complexes exceeds a predetermined threshold; and

declaring a VT event when the number of the tachycardia complexes classified as the VT complexes exceeds the predetermined threshold.

3. The method of claim 2, further comprising delivering a ventricular tachycardia therapy in response to the VT event being declared.

4. The method of claim 1, comprising:

sensing cardiac signals including NSR complexes; and

determining the NSR output template using the NSR complexes.

5. The method of claim 4, wherein determining the NSR output template using the NSR complexes comprises:

locating NSR feature points on sampled NSR complexes;

generating a NSR template using the NSR feature points;

creating a filter impulse response (h(t)) using the NSR template;

performing a numerical convolution of the NSR template and the NSR complex vectors to create a NSR filter output; and

creating the NSR output template using the NSR filter output.

6. The method of claim 5, wherein generating the NSR template comprises generating a NSR template including an average value for each of the NSR feature points.

7. The method of claim 5, comprising receiving cardiac rate signals and detecting a tachycardia event using the cardiac rate signals, wherein the tachycardia complexes are associated with the tachycardia event.

8. The method of claim 5, further comprising delivering appropriate cardioversion and defibrillation therapy for the classified tachycardia complexes.

9. The method of claim 5, comprising detecting the tachycardia complexes and the NSR complexes, wherein the tachycardia complexes and the NSR complexes are each a QRS-complex.

10. The method of claim 8, wherein generating the tachycardia complex output comprises performing a numerical convolution of the NSR template with tachycardia feature points.

20. The method of claim 5, further comprising delivering appropriate cardioversion and defibrillation therapy for the classified tachycardia complexes.

11. A method, comprising:

receiving cardiac signals including includes tachycardia complexes and normal sinus rhythm (NSR) complexes, the tachycardia complexes associated with a tachycardia event;

detecting the tachycardia event using the cardiac signals;

extracting a plurality of tachycardia feature points from each of the tachycardia complexes and a plurality of NSR feature points from each of the NSR complexes;

generating an NSR template using the plurality of NSR feature points extracted from the number of NSR cardiac complexes;

generating an NSR filter output using the NSR template and the plurality of NSR feature points for each of the NSR complexes;

determining an NSR filter output template using the NSR filter output for the each of the NSR complexes;

generating a tachycardia complex output using the NSR filter output template and the plurality of tachycardia feature points for each of the tachycardia complexes; and

classifying the each of the tachycardia complexes as a ventricular tachycardia (VT) complex or a supraventricular tachycardia (SVT) complex using the tachycardia complex output and the NSR filter output.

12. The method of claim 11, comprising declaring a VT event in response to a number of the tachycardia complexes classified as the VT complexes exceeding a predetermined threshold value.

13. The method of claim 12, further comprising delivering a ventricular tachycardia therapy in response to the VT event being declared.

14. The method of claim 11, comprising declaring an SVT event in response to a number of the tachycardia complexes classified as the SVT complexes exceeding a predetermined threshold value.

15. The method of claim 14, further comprising delivering a supraventricular tachycardia therapy in response to the SVT event being declared.

16. The method of claim 14, further comprising continuing to monitor cardiac condition without delivering a therapy to a supraventricular region in response to the SVT event being declared.

17. The method of claim 11, wherein generating the NSR template comprises generating an NSR template including an average value for each feature point of the plurality of NSR feature points.

18. The method of claim 14, wherein generating the NSR filter output comprises convolving the plurality of NSR feature points with the NSR template, and generating the tachycardia complex output comprises convolving the plurality of tachycardia feature points with the NSR filter output template.

19. The method of claim 15, wherein classifying the each of the tachycardia complexes comprises:

comparing the tachycardia complex output to the NSR filter output template to form a differentiation value;

comparing the differentiation value to a predetermined value; and

classifying the each of the tachycardia complexes as the VT complex or the SVT complex using an outcome of the comparison of the differentiation value to the predetermined value.