Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2000-11-02
2003-04-22
Jastrzab, Jeffrey R. (Department: 3762)
Surgery
Diagnostic testing
Cardiovascular
Reexamination Certificate
active
06553251
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method and heart rate monitoring equipment for heartbeat detection on the basis of a heart rate signal.
2. Brief Description of the Related Art
A heart rate monitor is a device used in sports and medical science, by means of which it is possible to monitor heart functions, such as rate, standard deviation of heartbeat intervals or other corresponding heart rate information. With reference to
FIG. 2
, heart rate monitors are constructed in such a manner, for instance, that they comprise an electrode belt
202
which is placed on the chest of a person
200
and measures the heart rate, the heart beats measured by the belt being transmitted wirelessly or through a conductor to a receiver unit
204
strapped to the wrist. Further, heart rate monitors can be constructed in such a manner that the entire heart rate monitoring equipment
204
is strapped to the wrist, from which the heart rate is measured using either an electric signal generated by a heart beat or changes in blood vessel pressure. The heart rate monitoring equipment can also be located in its entirety on the chest, in which case any required displays and memory units are in an apparatus
202
located on the chest.
The operation of a heart rate monitor is based on the fact that the heart when contracting generates a series of electric pulses which can be measured everywhere in the body, thus also in the hands and fingers. The signal is called an EKG signal. It is possible to identify sections of the different functional cycles of the heart from-this signal, as shown in FIG.
1
. The figure shows the electric signal
100
generated by one heart beat on a time-signal strength level
108
. The Y axis shows the signal strength (P)
106
as a function of the time (T)
104
shown on the X axis. The signal can be divided into peaks,
102
A to
102
E, of which the cardiogram feature that is easiest to distinguish, the QRS complex (
102
B-
102
C-
102
D), is generated by the contraction of the ventricles. The time instant corresponding to an R peak
102
C of the cardiogram
100
is marked at time instant
104
A.
The amplitude of a typical EKG signal is 1 to 2 mV measured from the chest at a good electrode contact, but if the skin is dry, it can be as low as 200 &mgr;V. Measured from a finger or hand, the signal is much weaker than this. The most reliable heart rate measurement is obtained by QRS complex detection from an EKG signal, because it contains the highest amount of energy and its spectrum differs sufficiently from the spectrum of movement artefacts. When the heart rate increases as a result of strain, the duration and amplitudes of the features of an EKG signal remain nearly unchanged in a healthy person and only the distance from a P wave to the next P wave becomes shorter. The EKG spectrum contains the most significant frequency components from 2 Hz to approximately 20 to 30 Hz. The peak of the QRS complex is in the frequency range of 10 to 15 Hz. Most disturbances in heart rate measurement are caused by movement artefacts, and to minimize these disturbances, the electrode contact must be appropriate and the electrode material must be selected correctly. The spectrums of P waves, T waves and movement artefacts are in the frequency range of 1 to 5 Hz, which is below the frequency range of the QRS complex and thus easy to filter away. Disturbances caused by muscle movement disturb the measurement, because the spectrum of an EMG signal partly overlaps that of the EKG signal. EMG disturbances can be eliminated or significantly reduced by filtering the frequencies in question away from the EKG spectrum and by moving the electrodes away from large muscles which do not exist in hands. 50 Hz (60 Hz) network interference only occurs outdoors in the immediate vicinity of high-voltage lines. Indoors, network interference may disturb the measurement in hospitals and sports halls, for instance. This interference can be reduced with a band-stop filter without attenuating the frequency components of the actual EKG signal.
The heartbeat signal measured by wrist-held heart rate monitoring equipment from an electric signal or pressure pulse of the heart is thus weak and disturbed by electric signals generated by muscle movement. Present apparatuses are trained by means of a computer program, for instance, to identify the format of a QRS complex. The heart rate monitor must first collect the EKG signal of the user and the data is then downloaded into a computer. On the computer, a QRS complex is selected from the EKG signal and transmitted back to the heart rate monitor as a QRS model. Prior art solutions contain significant drawbacks. Known heart rate monitors which measure heart rate from the wrist require computer operations and additional work when the QRS complex is separated from the EKG data. Another drawback is that heart rate monitors require bidirectional telecommunications with the outside world.
SUMMARY
It is an object of the invention to implement an improved method for detecting heartbeat. This is achieved by the method described in the following. It is a method for heartbeat detection measuring the heart rate signal of a person from the person's skin in a first measuring area, measuring the heart rate signal of the person from the person's skin in a second measuring area simultaneously with the measurement made in the first measuring area, transmitting timing information formed of the heart rate signal measured in the first measuring area to a part of a device in the second measuring area, detecting the heartbeat by means of the heart rate signal measured in the second measuring area and the timing information received from the first measuring area.
The invention also relates to an arrangement for heartbeat detection. The arrangement comprises a first measuring device for measuring the heart rate signal of a person on the skin of the person in a first measuring area, a second measuring device for measuring the heart rate signal of a person on the skin of the person in a second measuring area simultaneously with the measurement made in the first measuring area, which first measuring device comprises a transmitter for transmitting the timing information formed in the first measuring area to the second measuring device which comprises a receiver for receiving the timing information sent from the first measuring device, and which second measuring device comprises detection means for detecting the heartbeat by means of the heart rate signal measured in the second measuring area and the timing information received from the first measuring device.
The invention also relates to a heart rate monitor for heartbeat detection. The heart rate monitor comprises one or more means for measuring a heart rate signal on the skin of a person, a receiver for receiving timing information related to the heart rate signal, detection means for heartbeat detection by means of the measured heart rate signal and the received timing information.
Preferred embodiments of the invention are set forth in the dependent claims.
The invention relates to heart rate monitors which measure the heart rate of a person during the actual measurement in an area of a weak heart rate signal. In this context, an area of a weak heart rate signal refers to other areas than the chest which in this application is called an area of a strong heart rate signal. An area of a weak heart rate signal refers, for instance, to the wrist of a person, even though the invention is not limited to using the wrist as the measuring area. Measuring a heart rate signal from the wrist or a corresponding location can be done in several different ways, such as by measuring the electric signal generated by a heart beat, by measuring a pressure pulse generated by a heart beat in a blood vessel, or by monitoring the changes in the transmission of light in tissue caused by blood circulation. In electric measurement, a first sensor, i.e. electrode, of the heart rate monitor is held against the left hand,
Hoffmann & Baron , LLP
Jastrzab Jeffrey R.
Polar Electro Oy
LandOfFree
Method and arrangement for heartbeat detection does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and arrangement for heartbeat detection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and arrangement for heartbeat detection will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3079503