GB2431997A

GB2431997A - Hand held wireless ECG monitor

Info

Publication number: GB2431997A
Application number: GB0522237A
Authority: GB
Inventors: Lindsay Molyneux
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-11-01
Filing date: 2005-11-01
Publication date: 2007-05-09
Also published as: GB0522237D0

Abstract

An electrocardiograph (ECG) monitoring system comprises a ball shaped housing 1, 2 to be held in the hands of a subject. The hand-held housing 1, 2 contains ECG monitoring circuitry 3-6, a battery 9 and a radio frequency transmitter 7. Electrodes are provided on the surface of the spherical housing 1, 2. The transmitter 7 wirelessly transmits measured ECG waveform data to a remote computer. The remote computer analyses the received data to check for anomalies, for example anomalies that warn of possible atrial fibrillation. The housing 1, 2 may be cylindrical instead of spherical.

Description

I

An electrocardiograph (EGG) monitor for quick diagnosis A number of recent developments have made possible the development of an instrument that will allow electrocardiograph readings to be made safely and quickly. As the proportion of older members of the population increases EGG readings for Atrial Fibrillation dection become both relevant and important.The facility of obtaining an EGG reading during a short general consultation would be very cost-effective in terms of lives, finance and heartbreak.

The nature of the invention is the combination of features that together realise a ECG monitor that takes a very short time to use and occupies very little space.

The features are: 1) The general availability of computers in the doctors surgery.

2) The Availability and low cost of radio links that do not need a special licence.

3) The development of a program that gives a good indication of the presence of Atrial fibrillation.

4) The USB interface or RS232 connection that allows peripherals to be easily connected to computers and importantly allows power to be drawn from the computer.

The device has two parts. These house either the electronics for the subject or the computer parts.

Figure 1 shows the subject parts. These are contained within a plastic container that is typically a plastic ball of about 5 inches in diameter. The subject holds this ball, I and 2 of figure 1, within their hands.

The ball has conductive areas on opposite sides which roughly correspond to the size of a palm. These form the input electrodes of the amplifier. Within the ball are the electronic circuits that take the EGG voltage waveform and frequency modulate a radio wave with it. This is then detected by a receiver attached to a computer demodulated and converted into digital form.

The ball also contains a small battery.

Block 3 of figure us an amplifier with a gain of about 1000.

Block 4 of figure 1 is a parallel -T filter that rejects interference at mains frequency (50 Hz) Block 5 of figure 1 is a buffer amplifier that feeds 6 which is a voltage-to-frequency circuit where the EGG waveform is turned into a frequency modulated pulse train with a centre frequency of about 1500 cycles per second. This pulse train drives a radio transmitter 7 in a band that does not need a special licence; this is typically 330 megacycles per second. 8 is a short (100 millimetres) length of wire that acts as an anal.

The battery holder of figure 1 typically contains 4 type AA battery cells,shown as 9 in figure 1. Though a single PP3 9 volt battery can also be used. Apart from the lead to the sides of the ball to the electronics inside the ball there are no connections to anything else so that the safety of the subject is assured.

The second unit of the apparatus is shown in Figure 2.

Is a piece of wire (100 millimetres long) that acts as an Anal for a radio receiver 4 tuned to the same frequency as the transmitter of the block 7 of figure 1.

The signal from the receiver is a pulse train modulated in frequency by the ECG waveform.

Block 3 of figure 2 is a frequency-to voltage converter the output of which is the original ECG waveform.

This waveform is then changed into a series of 8 bit numbers by the Analogue-to digital converter in block 2 of figure 2.

The USB (universal Serial Bus) device connects directly to the computer. It has two properties that are of use for the ECG device.

1) As well as information lines it also has a pair of supply lines which supply 5 volts at up to 100 milliamps. This is adequate power to supply the USB unit, the radio receiver, frequency-to-voltage converter and the analogue-to-digital converter. All of which are contained within a small box. (82X45X145 millimetres).

It is also possible to use an RS232 connection system to power the system.

The program.

The program is windows based. It takes a 20 second sample of the EGG waveform and as well as displaying it also stores it within the computer.

It has facilities for finding the QRS complexes (these are the spikes that occur with each heart beat) and then uses this information to calculate nor only the mean heart rate but also the beat-to beat variation.

It also can combine the 0.4 seconds of the waveform of each heart beat into one pattern. This makes this important part of the waveform clear as variation from beat to beat is diminished. Further analysis of this section of the waveform searches for the P wave. This important feature of the waveform is a good indication as to the presence or otherwise of Atrial Fibrillation.

The program also has facilities for printing the waveform and transmitting it by e-mail for expert analysis.

Because the apparatus is in two parts and there is no physical connection between the subject and the computer. The subject is therefor at no risk from a electrical shock. The fact that the computer can supply most of the power of the system means that the batteries can be small.

The invention is essentially the bringing together of a collection of well known devices to make a convenient safe ECG recording and checking system suitable for a doctors surgery.

Claims

Claims 1) An ECG (Electrocardiograph) recording system in two units,

one attached to the subject the other attached to a computer the two units communicating by a radio link.

2) An ECG recording system as described in claim I where the unit of the system attached to the subject is contained within a ball or cylindrical enclosure that contains the electronics necessary to turn the EGG voltage waveform into a modulated radio signal as weD as with the necessary battery.

3)An EGG recording system, as described in claim 2, where the unit attached to the subject is held by the subject and so takes up no space on the doctors desk.

4) An EGG recording system as described in claim 2 where a magnetic field is created outside the ball and detected within it and is used to charge the battery between measurements.

5) An EGG recording system as described in claim 2 where the battery is connected to the electronic circuits by a microswitch switch positioned so that when the ball is on a flat surface the battery is disconnected.

6) An EGG recording system as described in claim I because there is no direct connection between the subject and the computer there is no electrical danger to the subject.

7) An EGG recording system as described in claim I where the unit attached to the computer draws power from a USB or RS232 connection system.

8) An ECG recording system described in claim I where the recording can be sent by e-mail from the computer for further analysis.

9) An ECG recording system as described in claim I that has facilities in the computer program to check for anomalies in the waveform warning of possible Atrial fibrillation.

10) An ECG recording system as described in claim I that in addition to warning of Atrial Fibrillation can also check for other anomalies.

11)A container that houses a battery and circuits that amplify and use the voltages from electrodes on its surface to modulate a radio transmitter contained within it.

12) The system described in claim 11 used to detect and transmit electrocardiograph signals from the hands of a subject holding the container.