Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2000-04-28
2002-11-26
Getzow, Scott M. (Department: 3762)
Surgery
Diagnostic testing
Cardiovascular
C600S519000
Reexamination Certificate
active
06487442
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The normal heart rate is slightly irregular. Generally, normal irregularity of the heart rate reflects the permanent adaptation of the human body to the environment. In this context the first sign of an impaired heart rate is either a persistent increase or a persistent decrease in the variability of the heart's rate. Sometimes the change in the heart rate alternates between increases and decreases in the variability of the heart's rhythm, and vice versa. Prolonged increases, or decreases, and combinations thereof, can lead to cardiac adverse events ranging from non-sustained ventricular tachycardia to cardiac arrest.
It is believed the variability of the heart rate is controlled by two branches of the autonomic nervous system; the sympathetic branch and the parasympathetic branch. The sympathetic branch increases the heart rate. Its prime function is to prepare the body for stress, the so-called “fight or flight response.” The parasympathetic branch decreases the heart rate as when eating or sleeping.
This invention relates to the detection of normal and abnormal heart rate variability and the induction of normal heart rate variability. More particularly, the invention relates to methods and apparatus for the detection of a patient's heart rate variability that we believe is indicative of a patient's sympathetic/parasympathetic stress balance, or distress imbalance.
The invention also relates to heart monitoring devices used by individuals monitored in hospital intensive care units; by patient's after discharge from a hospital intensive care unit; and by patients when exercising to let them know that their stress state is optimal for conditioning their bodies.
The invention further relates to control of a pacemaker or cardioverter defibrillator with a pacemaker so that when the patient's heart rate is abnormal and distressful, according to the invention, a pacemaker or cardioverter defibrillator with a pacemaker induces a heart rate with a pseudo-normal or patient recorded variability for each particular patient.
The invention still further relates to a pacemaker that induces pseudo-normal or patient recorded heart rate variability.
2. Background Description
In the Soviet Union, Rhythmography, that is the study of normal and abnormal variations in the heart, was utilized extensively to determine the condition of individuals and their stress state. This was particularly true of cosmonauts. It was determined, for example, that the heart rate variability of a conditioned athlete is much greater than that of person with coronary disease. That is, the histogram of heart rate variation of a well conditioned athlete exhibits a broad range of variability in the Time Intervals between heart beats and a low relative Amplitude of the Mode. That is the highest number of Time Intervals recorded in a series of Time Intervals. The histogram of a person with a coronary disease exhibits a narrow range of variability and a high relative Amplitude of the Mode, that is the peak of the histogram.
Boris Golosarsky, previously received two patents in the Soviet Union, namely SU-1683679 and SU-1769894. SU-1683679 is for an apparatus, which enables a physician to determine the arithmetic Mean, the Mode, the relative Amplitude of the Mode, and the range of variability of a subject. In the second patent in the Soviet Union, SU-1769894, he disclosed how these measurements may be utilized together with electrosleep to treat post myocardial infarction e.g., heart attack patients.
GW Scientific, Inc. measured a patient's heart rate variability in relation to the patient's baseline heart variability using mathematical constructs such as UV, AMo, and DX, all as described in U.S. Pat. No. 5,718,235, incorporated herein by reference in its entirety.
Polar Electro Oy of Finland has a patented apparatus comprised of a chest strap with a two lead ECG signal sensor and transmitter, which transmits the heart beat Time Intervals to a wrist mounted unit that can be conveniently used in this invention. See U.S. Pat. Nos. 4,625,733; Des. 278,746; and Des. 287,403, all incorporated herein by reference in their entirety.
Pulse sensors of various types may also be used to detect the Time Interval between heart beats, (Start-of-Systole to Start-of-Systole, SOS), is essentially equal to the Time Interval between RR peaks in an electrocardiogram, (ECG).
Additional background information is disclosed by Baevsky, R. M., Kirillow, O. I., Kleckin, C. Z., (1984),
Mathematical Analysis of Stress Changes in Heart Rhythm
, Moscow, Academy of Science, USSR.
Schmidt et al, “Heart-rate Turbulence After Ventricular Premature Beats As a Predictor of Mortality After Acute Myocardial Infarction,” Lancet Apr. 24, 1999; 353 (9162):1390-6, relates to ACRRs. This article discloses a formula for predicting myocardial infarction 21 to 24 months in advance. In contrast, the present invention predicts up 24 hours in advance. The formula in this article is quite different from those employed in the present invention.
SUMMARY OF THE INVENTION
Definitions
TABLE A shows there are five abnormal predictive markers, which are comprised of two continuums, the Heart Rate Variability continuum and the Heart Rate continuum, as well as Erratic Variability. The Heart Rate Variability continuum has, as its extremes, high and low variability. The Heart Rate continuum has, as its extremes, bradycardia and tachycardia. Erratic Variability, is comprised of Premature Ventricular Contractions (PVCs) and Atrial Fibrillation (A-Fib). TABLE A lists the parameters in each continuum Values for these parameters are calculated by formulas and compared with values which are considered normal and values which are considered abnormal as explained in the specification. These parameters in TABLE A are also labeled by reference numerals and these reference numerals may be employed elsewhere in the specification when discussing the parameters.
TABLE A
HEART RATE VARIABILITY CONTINUUM
High Variability
Normal
Low Variability
dispersion of heart beats
centrality of heart beats
Absolute SPS(1)
Normal
Absolute SPS(2)
Absolute AMo(3)
Normal
Absolute AMo(4)
Absolute DX(5)
Normal
Absolute DX(6)
Absolute DX/Median(7)
Normal
Absolute DX/Median(8)
Low HRV(9)
2.0 Caution > 2.5
ALARM(10)
HEART RATE CONTINUUM
bradycardia(11)
Normal
tachycardia(12)
ERRATIC VARIABILITY
ACRR(13)
PVCs & A-Fib
Data sources: ECG (RR) Time Intervals or pulse wave Start-of-Systole to Start-of-Systole (SOS) Time Intervals from the hardware sources discussed elsewhere. (Note: RR and SOS Time Intervals are used interchangeably to indicate the Time Interval between heart beats. 60 seconds divided by the Time Interval in seconds equals beats per minute, bpm.)
Time Interval: A Time Interval is the duration of time between heart beats, or RR peaks, preferably measured to an accuracy of 20 milliseconds, 0.02 seconds. The accuracy of the Time Interval can range from 15 milliseconds to 30 milliseconds.
Time Segment: A Time Segment is a series of Time Intervals, which can vary in length from 51 Time Intervals to 301 Time Intervals. The preferred default setting is 101 Time Intervals. Typically, from this 101 Time Intervals, up to about 6 outliers are removed.
The time between each heart beat is designated an RR Time Interval. RR Time Intervals are then divided into three subsets as shown in TABLE B.
TABLE B
RR Time Intervals (milliseconds)
NN
ACRR
MARR
75 to 125
1 to 74 and/or 126 to 169
0 and/or 170+
(Normal-to-Normal): Normal-to-Normal means a normal Time Interval between an RR peak. NN Time Intervals are used to calculate twelve of the thirteen predictive markers. NN equals 75 to 125 milliseconds.
ACRR (Abnormal Cardiac RR): Abnormal Cardiac RR means when the present Time Interval differs from the previous Time interval by +25% or −25%, and this situation occurs 50 or more times while accumulating a Time Segment of 101 NN Time Intervals, then this Time Segment is an ACRR Time Segment. If this condition persists fo
Getzow Scott M.
Stevens Davis Miller & Mosher LLP
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