Pacemaker system for preventing ventricular tachycardia

• US 6,370,431 B1
• Filed: 01/27/1999
• Issued: 04/09/2002
• Est. Priority Date: 10/26/1998
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Van Groeningen, Christianus J. J. E., De Vries, Bernhard A. P., Van Oort, Geeske, Stoop, Gustaaf A. P.
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/237,815
• Time in Patent Office: 1,168 Days
• Field of Search: 607/14, 607/25, 600/516
• US Class Current: 607/14
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

There is provided a pacemaker system which includes intervention for overdriving the patient'"'"'s natural heart rate in the event of a sensed incipient ventricular arrhythmia condition, and particularly torsades de pointes. The pacemaker continually acquires QT signals and analyzes them for respective properties, updating statistical information relating to the properties. In a preferred embodiment, the pacemaker analyzes QT interval, QT dispersion, time derivative of the QT interval, and/or T-wave amplitude and determines an intervention for pacing therapy based upon changes to these properties. The pacemaker also monitors premature ventricular beats and generates data representative of such occurrences, which data is used alone or in combination with QT data in determining whether intervention is indicated, for adjusting the intervention pacing rate. There is thus provided a systematic approach for monitoring relevant data so as to reliably determine when intervention pacing therapy is needed, and for adjusting the intervention pacing rate.

Claims

1. a pacemaker system for pacing a patient, said pacing including overdriving the patient'"'"'s heart for prevention of ventricular arrhythmias, said system having ventricular generator means for generating and delivering ventricular pace pulses, and ventricular sense means for sensing QT signals, said system further comprising:

QT analysis means for analyzing at least two properties of the patient'"'"'s QT signal and for obtaining QT data representative variations of said at least two respective properties of said QT signal, said QT analysis means comprising means for analyzing QT interval and QT dispersion as said at least two properties;

VES means for determining when ventricular extra systoles occur and for generating VES data representative of said occurrences;

intervention means for determining from said QT data and said VES data when intervention is indicated order to treat a ventricular arrhythmia; and

rate means for controlling said ventricular generator means to generate and deliver pacing pulses at an intervention rate greater than the patient'"'"'s natural rate in response to a said indication;

wherein said QT analysis means comprises means for continually determining a means value and standard deviation value of each of said QT properties and for updating said values when a respective QT property exceeds its mean value by more than n times its standard deviation.

2. A pacemaker system or pacing a patient, said pacing including overdriving the patient'"'"'s heart for prevention of ventricular arrhythmias, said system having ventricular generator means for generating and delivering ventricular pace pulses, and ventricular sense means for sensing QT signals, said system further comprising:

QT analysis means for analyzing at least two properties of the patient'"'"'s QT signal and for obtaining QT data representative of variations of said at least two respective properties of said Qt signal, said QT analysis means comprising means for analyzing QT interval and QT dispersion as said at least two properties;

VES means for determining when ventricular extra systoles occur and for generating VES data representative of said occurrences;

intervention means for determining from said QT data and said VES data when intervention is indicated in order to treat a ventricular arrhythmia; and

rate means for controlling said ventricular generator means to generate and deliver pacing pulses at an intervention rate greater than the patient'"'"'s natural rate in response to a said indication;

wherein said intervention means comprises a respective variation means for determining respective measures of variation of each of said properties, and composite means for obtaining a composite measure of QT property variations from said respective measures, and wherein a change means comprises means for changing said intervention rate as function of said composite measure.

3. The pacemaker system as described in claim 2, wherein said change means comprises means for changing said intervention rate as a function of said composite measure and said VES data.

4. A pacemaker system for pacing a patient, said pacing including overdriving the patient'"'"'s heart for prevention of ventricular arrhythmias, said system having ventricular generator means for generating and delivering ventricular pace pulses, and ventricular sense means for sensing QT signals, said system further comprising:

QT analysis means for analyzing at least two properties of the patient'"'"'s QT signal and for obtaining QT data representative of variations of said at least two respective properties of said QT signal;

VES means for determining when ventricular extra systoles occur and for generating VES data representative of said occurrences;

intervention means for determining from said QT data and said VES data when intervention is indicated in order to treat a ventricular arrhythmia; and

rate means for controlling said ventricular generator means to generate and deliver pacing pulses at an intervention rate greater than the patient'"'"'s natural rate in response to a said indication;

wherein said VES means comprises means for determining the recent frequency of VES occurrences, and said intervention means comprises means for determining change of said intervention rate as a function of frequency of VES occurrences.

5. A pacemaker system for pacing a patient, said pacing including overdriving the patient'"'"'s heart for prevention of ventricular arrhythmias, said system having ventricular generator means for generating and delivering ventricular pace pulses, and ventricular sense means for sensing QT signals, said system further comprising:

QT analysis means for analyzing at least two properties of the patient'"'"'s QT signal and for obtaining QT data representative of variations of said at least two respective properties of said QT signal;

VES means for determining when ventricular extra systoles occur and for generating VES data representative of said occurrences;

intervention means for determining from said QT data and said VES data when intervention is indicated in order to treat a ventricular arrhythmia; and

rate means for controlling said ventricular generator means to generate and deliver pacing pulses at an intervention rate greater than the patient'"'"'s natural rate in response to a said indication; and

limit means for limiting the increase of said intervention rate to a rate which corresponds to an escape interval which is at least as great as the current QT interval plus a predetermined value.

6. A pacemaker system for pacing a patient'"'"'s heart, said system having generator means for generating and delivering ventricular pace pulses and sensing means for sensing patient ventricular signals, comprising:

QT means for obtaining and storing data representative of the patient'"'"'s QT signal;

analyzing means for analyzing said QT data to obtain parameter values representative of a plurality of respective QT parameters, and comparison means to compare each parameter value with a statistical measure of recent said parameter values to obtain a change measure representative of change of each said parameter;

intervention means for determining, as a function of said change measures, an intervention pacing said patient so as to provide therapy for long QT syndrome; and

control means for controlling said generator means to generate and deliver ventricular pace pulses at said intervention rate

wherein said analyzing means further comprises;

first means for obtaining values representative of QT interval;

second means for obtaining values representative of QT dispersion; and

third means for obtaining values representative of QT time derivative.

7. A pacemaker system for pacing a patient'"'"'s heart, said system having generator means for generating and delivering ventricular pace pulses and sensing means for sensing patient ventricular signals, comprising:

QT means for obtaining and storing data representative of the patient'"'"'s QT signal;

analyzing means for analyzing said QT data to obtain parameter values representative of a plurality of respective QT parameters, and comparison means to compare each parameter value with a statistical measure of recent said parameter values to obtain a change measure representative of change of each said parameter;

intervention means for determining, as a function of said change measures, an intervention pacing rate for pacing said patient so as to provide therapy for long QT syndrome; and

control means for controlling said generator means to generate and deliver ventricular pace pulses at said intervention rate

wherein said analyzing means further comprises T-wave amplitude means for analyzing T-wave amplitude, and means for determining a measure of change in T-wave amplitude.

8. The pacemaker system as described in claim 7, comprising means for obtaining a statistical measure of each said QT parameter.

9. A pacemaker system for pacing a patient'"'"'s heart, said system having generator means for generating and delivering ventricular pace pulses and sensing means for sensing patient ventricular signals, comprising:

VES means for obtaining and storing VES data representative of VES occurrences;

intervention means for determining, as a function of said VES data, an intervention pacing rate for pacing said patient so as to provide overdrive pacing therapy; and

control means for controlling said generator means to generate and deliver ventricular pace pulses at said intervention rate;

wherein said intervention means comprises means for incrementing said intervention pacing rate by a minimum increment when there has been just one VES in the last Y cycles.

10. The pacemaker system as described in claim 9, wherein said intervention means comprises means for incrementing said intervention pacing rate by more than said minimum increment when there has been a VES occurrence during X of the last Y cycles.

11. A pacemaker system for pacing a patient'"'"'s heart, said system having generator means for generating and delivering ventricular pace pulses and sensing means for sensing patient ventricular signals, comprising:

VES means for obtaining and storing VES data representative of VES occurrences;

intervention means for determining, as a function of said VES data, an intervention pacing rate for pacing said patient so as to provide overdrive pacing therapy;

control means for controlling said generator means to generate and deliver ventricular pace pulses at said intervention rate; and

VES frequency means for determining a measure of the frequency of said VES occurrences, and wherein said invention means comprises means for determining said intervention pacing rate as a function of said VES frequency measure.