JPS6018419B2 - Demand type pacemaker - Google Patents

Description

[Detailed description of the invention] The present invention relates to a cardiac signal identification device.

Demand-based cardiac basses are well known to those skilled in the art.

Such a vasa delivers cardiac stimulation pulses to the patient's D heart only when the natural heart barrel has disappeared. If only one natural mandrel disappears, it will give only one stimulation pulse. If one or more natural mandrels disappear, the same number of stimulation pulses are given.

A typical demand type D viscera produces stimulation pulses with a time interval that approximates the velocity of the natural mandrel.

Detection of a natural heart characteristic inhibits the next stimulation pulse that would otherwise occur. Inhibiting the stimulation pulse restarts the Basa timing cycle so that the next stimulation pulse (if needed) occurs approximately at the same time as the expected natural hemorrhoid. Regardless of the number of stimulation pulses that occur, the stimulation pulses are generated in a timing cycle such that they occur at essentially the same time intervals between each other and with the natural mandrel, as if they were all heartbeats. Pulse generation restarts. In practice, it has been found that other signals can inhibit the generation of stimulation pulses just as in the natural mandrel.

For example, strong electrical signals encountered in ordinary environments, such as stray 60 (50) Hertz power, will do such a thing as to inhibit the stimulation pulse as if a natural mandrel were detected. Examples of this type of external noise include noise emitted from electric razors, electric drills, car ignitions, and the like. To prevent stimulation pulses from being inhibited by external noise, typical prior art demand-type cardiac basers included a noise rejection circuit.

In fact, this circuit detected the repeatability of the noise and blocked all inhibit signals to the pulse generator when such noise was present. In other words, inhibit signals resulting from external noise and natural mandrel sensing are blocked at the pulse generator, causing the baser to return to an asynchronous mode of operation. In the asynchronous mode, the stimulation pulses compete with the heart's natural potential, causing irregularities in function in the heart. Furthermore, asynchronous operation makes it impossible to protect battery power used in demand mode operation. The present invention provides a demand-based cardiac baser that is capable of detecting the natural activity of the heart in the presence of repetitive external noise.

The circuit that performs this function also prevents non-repetitive signals whose amplitude is below a predetermined value. A rectifier circuit controls the charge on the capacitor and sets the charge to a reference level representative of sensed repetitive external noise and a second level representative of sensed cardiac activity. The sensing circuit is responsive to the difference between the reference level and the second level and issues a pulse generator reset signal when said difference is greater than a predetermined value. If the second level set by the non-repetitive signal is less than the predetermined value, it is blocked and the circuit has an inactive period to limit the repetition rate of the reset signal. Thus, a demand-type axillary base operating in accordance with the present invention will be inhibited by the natural activity of the heart even when the activity is masked by repetitive external noise. Inhibition of stimulation pulses due to non-repetitive and low frequency noise can be limited to medium intensity by defining circuit parameters such that stimulation pulses cannot be inhibited unless the signal is greater than a predetermined value. Ru. Also, the frequency of the reset signal given to the basser's pulse generator (
A period of inactivity is provided to limit the frequency. Next, embodiments of the present invention will be described with reference to the drawings.

The invention is best understood with reference to FIGS. 1 and 2. FIG. FIG. 1 shows an intensifier 10 and a jamming prevention device 11.
, shows a demand type cardiac baser according to the prior art having a pulse generator 12 and output devices 13 and 14 for connection to the heart for sensing cardiac activity and for providing stimulation pulses to the heart. In the absence of external noise, the signals indicative of cardiac activity sensed at the output devices 13 and 14 are intensified in the intensifier 10' and transmitted to the anti-jamming device 1.
1 and reaches the pulse generator 12 as a reset signal. The signals sensed at the output devices 13 and 14 are all intensified by the intensifier 10 to the maximum value possible with the power of the baser. As mentioned above, output devices 13 and 14 not only sense cardiac activity, but also external noise.

These noise signals are intensified by the intensifier 1 to the same maximum level as the cardiac activity signal;
If not prevented, the pulse generator 12 will be reset. Since the signals received by the jamming prevention device 11 are of substantially the same frequency, the jamming prevention device 11 responds only to the repetitive nature of the amplified signal and blocks all signals to the pulse generator 12 due to the presence of the repetitive signal. do. Therefore, even if the signal provided to the jamming prevention device 11 contains a component indicative of sensing cardiac activity, this component is masked by the presence of some repetitive form of disturbance, and the jamming prevention device 11
1 prevents it from entering the pulse generator 12.
In contrast, a non-repetitive signal applied to the jamming rejection device 11 will appear as a signal indicative of sensing cardiac activity and will pass through the jamming rejection device to reset the pulse generator 12. As is clear from the above, the demand type Shinnu baser which operates according to the principle shown in Fig. 1 turns into asynchronous operation due to the presence of repetitive noise.
It is also reset by a repetitive noise signal even in the absence of natural cardiac activity. Of course, it would be possible to use radio wave techniques known to those skilled in the art for the baser of FIG. 1 in an attempt to distinguish between cardiac activity and external noise. However, it is very difficult to provide a reactor with sufficient discrimination to eliminate all the undesirable effects of external noise, especially those arising from the commonly encountered 60 hertz frequency. FIG. 2 shows a demand-type cardiac base using the device of the present invention.

The pulse generator 12 and output devices 13 and 14 are identical to those of the apparatus of FIG. For example, pulse generator 1
2 may be of known type with a resettable timing circuit. A common output device 13, such as an electrode, is suitable for making a connection with the heart for sensing the natural activity of the heart and for providing stimulation pulses from the pulse generator 12. Further output devices 14, such as electrodes, are also provided in a known manner. A cardiac base using the device of the present invention has a pre-layer intensifier 15, as shown in FIG. The signals appearing at 13 and 14 are
The various components making up the disturbance identification device 16 according to the invention are increased to a sufficient level to allow switching.

Thus, the signal applied to the disturbance identification device 16 has a repetition rate that is indicative of the repetition rate of the signal sensed at the output devices 13 and 14, and has an oscillation that is representative of the oscillation of the sensed signal. Become. The disturbance identification device is responsive to the repetition rate and duration of the sensed signal to establish a reference level representative of the repetition signal and a second level representative of the sensed cardiac activity. If the difference between this criterion and the second level is greater than a predetermined value, the disturbance identification device 16 generates a pulse generator reset signal, which signal is transmitted by the multiplier 17 to the maximum value obtained by the power supply of this baser. Increased to the value. This increased reset signal causes the pulse generator 12 to
is reset and stimulation pulses are inhibited. For known reasons, the interference identification device is provided with inactive periods in order to limit the frequency of the reset signal. Next, FIG. 3 shows a circuit diagram of an embodiment of the present sea bream D viscera signal identification device used in the demand type D pork basser shown in FIG. 2.

The illustrated part is a disturbance identification device 16 comprising an intensifier section 15, a rectifier section 20, and a detector section 21.
The intensifier unit 15 includes a Takagi pass-through reactor composed of a capacitance 22 and a resistor 23, an inverting intensifier 24, and
It is composed of a low-pass wave generator consisting of a resistor 25 and a capacitance 26. The gain of the multiplier 24 is less than the gain of the multiplier 10 (see FIG. 1) used in the slave device, and this multiplier 24 has a gain smaller than that of the multiplier 10 (see FIG. It is designed to provide sufficient signals to perform its functions. That is, the signal from the multiplier 24 has an amplitude that is less than the maximum amplitude set by the power supply of this baser. The inverting function of the multiplier 24 consists of a capacitance 22 and a resistor 23, which are intended to match the polarity of the signal representing the sensed R-wave to the polarity of the transistor constituting the disturbance identification device according to the invention. The high-pass reactor waver operates as a passive differentiator for reasons detailed below.

Alternatively, the intensifier 24 may be operated as an active differentiator with or without the high-pass and low-pass wavers. Except for the differential function performed by the high-pass filter waver, this high-pass filter waver and low-pass filter waver are used only to illustrate that known wave technology can be used in the disturbance identification system of the present invention. Indicated. By differentiation by either active or passive circuits,
The signal appearing at node 27 is representative of the change in vibration sensed at output devices 13 and 14 over time.

This differentiation function is well known to those skilled in the art. For example, the repetitive signals applied to output devices 13 and 14 are
An envelope at the connection point 27, ie, an envelope having a duration indicating the duration of the repetitive signal and a midpoint indicating the midpoint of the repetitive signal, is determined. In the figure, signal 2
8 is a differentiated signal of the 60 Hz repetitive signal appearing at the subsequent point 27, and the straight line serving as the boundary between the upper and lower portions of this signal defines this envelope. Output device 1
A single pulse such as the sensed R-wave appearing at 3 and 14 becomes a pulse signal at connection point 27. Such a pulse signal is indicated by 29. As is well known to those skilled in the art, the repetitive signal and the sensed R-wave are transmitted to the output device 1.
3 and 14, it appears at connection point 27 at 3
It becomes one signal as shown by 0. This signal 30',
It is an envelope with a duration equal to the duration of the repeating signal and a midpoint set primarily by the midpoint of the repeating signal. Peak 31 in the oscillation of signal 30 is the result of simultaneous differentiation of the repetitive signal and the sensed R wave. Connection point 27 is connected to base 35 of transistor 36. The collector 37 of the transistor 36 is a resistor 39
The emitter is connected to the -power supply via a resistor 41. The base 43 of the second transistor 42 is connected to a node 44 between the resistor 39 and the collector 37 of the transistor 36 . Emitter 4 of transistor 42
5 is connected to the power supply, and its collector is connected to connection point 46. The connection point 46 is connected to a base electrode 47 of a transistor 48, and its emitter electrode 49 is connected to a power source via a resistor 41. A collector electrode of the transistor 48 is connected to the power supply 38. Connection point 46
is connected to the -power supply via a capacitance 51. Transistors 36 and 48 constitute a differential intensifier, which together with transistor 42 rectifies the differentiated signal appearing at node 27.

For example, a differentiated 60 hertz signal such as shown at 28 turns transistor 36 on and off continuously. When transistor 36 is on, node 44 is negative, which turns transistor 42 on. The capacitor 51 is charged while the transistor 42 is on, and the capacitor 51 is charged while the transistor 42 is on.
2 is off, it discharges through resistors 53 and 54. The combined resistance with resistors 53 and 54 is selected to provide a large time constant with capacitance 51 so that capacitance 51 discharges very slowly while transistor 42 is off. Thus, sensing a repetitive signal at output devices 13 and 14 will charge capacitor 51 to a reference level representative of the repetitive signal sensed at output devices 13 and 14. Non-repetitive signal or capacitor 51 is connected to transistor 42
For sufficiently low frequency repetitive signals that discharge during the off-time of capacitor 51, the reference level set on capacitor 51 is zero. When output devices 13 and 14 sense repetitive signals and cardiac activity such as R waves, a signal having a peak 31 as shown at 30 appears at connection point 27.

Before the appearance of a signal sensing cardiac activity, capacitance 51 is charged to a reference level set by the repetitive signal. This reference level is indicated at 30' in FIG. When the peak 31 appears at the connection point 27, the canon 51 is charged to a second level above the reference level 30'. The second level is shown in FIG. 3 31'. From this, the rectifier section 20 of the disturbance identification device 16 is connected to the connection point 27.
Take the differentiated signal appearing at and at the connection point 46,
A DC voltage having a reference level representing a sensed repetitive external noise and a second level representing sensed cardiac activity. Connection point 46 is connected to connection point 55 by resistor 56.
It is connected to the. The connection point 55 is connected to the − power supply by a capacitor 57 and is also connected to a base electrode 58 of a transistor 59 . A collector electrode 60 of the transistor 59 is connected to the power supply 38, and an emitter electrode 61 is connected to the power supply through a resistor 62. Resistors 53 and 54 constitute a voltage divider, and an intermediate connection point 63 thereof is connected to a base electrode 64 of a transistor 65. A collector electrode 66 of the transistor 65 is connected to a connection point 67, and its emitter is connected via a resistor 62 to the -power supply. Connection point 67 is connected to +power supply 38 via resistor 69 and is also connected to base electrode 70 of transistor 71 .
The emitter pole 72 of the transistor 71 is connected to the power supply 38,
Its collector electrode 73 is connected to a reset signal generator 74. Transistors 59 and 65 constitute a differential amplifier, turning on transistor 71 when the voltage applied to the base electrode 64 of transistor 65 is greater than the voltage applied to the base electrode of transistor 59. When the transistor 71 is turned on, it provides an activation signal to a reset signal generator 74 consisting of a monostable multipipulator with a built-in inactive period. The output of the reset signal generator 74 is increased, if desired, to the maximum level that can be set by the baser's power supply, and this increased signal is used to reset the pulse generator 12 (see FIG. 2). , the stimulation pulses appearing on the output devices 13 and 14 can be inhibited.During the inactive period of the reset signal generator 74, non-repetitive or low frequency signals sensed by the output connections 13 and 14 are inhibited. Reset signal generators with this inactive period are well known to those skilled in the art. The signal appearing at node 46 passes through resistor 56 to transistor 59 and reaches the base electrode 64 of the transistor 65 via the resistor 53.

However, the capacitor 57 acts to keep the connection point 55 and thus the base electrode 58 of the transistor 59 at its previous level, so that the change in potential at the Yabuhosugi point 46 causes the base electrode 58 to remain at its previous level.
is delayed from being applied. When a pure repetitive signal is sensed, node 46 is at a reference level, and this voltage is applied to base electrode 58 while a predetermined voltage less than this reference level is applied to base electrode 64. is applied to In this state, transistor 65
remains off. When a peak 31 appears at the bale box chord point 27, this peak is rectified and appears at the connection point 46 as a peak 31'. This rectified peak is applied to the base electrode 64 and the capacitor 5 to the base electrode 58.
7 and is applied with a delay. If the difference between peak 31' and reference level 30' is greater than the voltage drop across resistor 53, transistor 65 is turned on and node 6
7 are driven together. When node 67 goes negative, transistor 71 turns on, providing an activation signal to reset signal generator 74, and transmitting a pulse generator reset signal to inhibit stimulation pulses from pulse generator 12. As can be seen from the above, the invention comprises a disturbance identification device having a rectifier section for setting a first voltage level representative of repetitive external noise and a second voltage level representative of cardiac activity.

This voltage level is set by a rectifier circuit that operates on the differential of the sensed signal. The detector portion is responsive to the rectified voltage level to provide an activation pulse to the reset signal generator when a voltage level is generated indicative of sensing cardiac activity. Thus, a demand type baser operating in accordance with the present invention will remain in demand mode even in the presence of repetitive external noise, except for large external noises such that capacitor 51 is at the level of power supply 38. Continue operation.
Furthermore, non-repetitive or low frequency noise
The stimulation pulse is inhibited only when the voltage level set by the rectifier section of the disturbance identification device rises above the reference voltage level by more than the voltage drop across the resistor 53, but only during the inactive period of the reset signal generator 74. Only when sent. The main advantage of the present invention is that it amplifies all signals sensed by output devices 13 and 14 to a level lower than the maximum level possible with the baser power supply, and that the disturbance identification device of the present invention is used for this amplification. obtained by operating at a constant and repetition rate of the signal.
Obviously, many modifications and variations of the invention are possible in light of the above description.

One example of such an obvious modification is a change in the polarity of the various circuit elements shown and described. Also, by changing the resistor 53, the sensitivity of this interference identification device can be changed. That is, if the resistor 53 is increased, the R wave, non-repetitive noise signal, or low frequency repetitive signal must be increased in order to start the reset signal generator 74.
The noise discrimination device of the present invention effectively blocks repetitive noise signals of approximately 5 hertz or higher and prevents the generation of cardiac stimulation pulses in response to R waves that are masked by repetitive external noise that is several times louder than the R waves themselves. prohibit. It will be obvious that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described above. The embodiments of the present invention are as follows.

{11. Device according to claim 1, characterized in that the first circuit comprises a rectifier device.

{21. Apparatus according to claim 1, characterized in that the second circuit has inert means for limiting the rate of generation of the signal indicative of sensing cardiac activity.

'3} The first circuit comprises capacitor means and means for charging the capacitor means to the reference level in response to repetitive external noise and to the second level in response to sensed cardiac activity. Apparatus as claimed in the claims.

2. The apparatus of claim 3, wherein the charging means for the capacitance means comprises differentiating means and means responsive to the differentiating means for controlling the charge level of the capacitor means.

'5} The device according to item 4, wherein the charging control means comprises differential intensifier means.

(2) The device according to item 4, wherein the charging control means includes rectifier means. 7} The device of claim 6, wherein the second circuit includes inert means for limiting the rate of generation of the signal indicative of sensing cardiac activity.

2. A device according to claim 1, characterized in that said second circuit comprises differential multiplier means. {91 Said second
The circuit further comprises means for generating a signal indicative of cardiac activity in response to the differential intensifier means, the signal generating means having inert means for limiting the rate of the signal. 9. The device according to item 8. '1) first means connected to the sensing means and generating a signal indicative of sensing cardiac activity in response to the repetition rate and duration of the signal sensed by the sensing means; and second means connected to the means for generating a pulse generator reset signal in response to the cardiac activity signal.
An improvement in a demand-type cardiac bench having a resettable pulse generator and suitable means for connecting to the heart for sensing cardiac activity.

(11) The device according to page 10, wherein the reset signal generating means includes inactivation means for limiting the repetition rate of the reset signal.

(12) The first means includes capacitance means;
Apparatus according to page 10, further comprising means for charging the capacitance means to a first level representative of a sensed repetitive noise and a second level representative of sensed cardiac activity. (13) The device for the IZ commission battle, wherein the second means includes means responsive to the difference between the first and second levels.

(13) The device according to item 12, wherein the second means further comprises deactivation means for limiting the reset signal repetition rate.

(15) The second means includes a differential intensifier that outputs a control signal when the difference between the first and second levels exceeds a predetermined value. equipment.

(16) The eighteenth aspect further includes means for generating a reset signal in response to the control signal, and the reset signal generating means includes inactivation means for limiting the repetition rate of the reset signal. A device for entrusted teaching. 07) The device according to page 12, characterized in that the capacitance means charging means has a rectifying means.

18. The apparatus of claim 12, wherein said capacitance means charging means comprises differentiating means and means responsive to said differentiating means for controlling the charge level of said capacitor means.

(19) The device as set forth on page 18, wherein the charging control means includes differential intensifier means. (20) The above-mentioned second means further comprises inactivation means for limiting the repetition rate of the reset signal.
Device described on page. (21) differentiating means connected to said sensing means, capacitance means, and said capacitance means connected to said differentiating means for generating a signal having an amplitude and repetition rate representative of the signal sensed by said sensing means; means for charging the capacitance to a first level representative of a repetitive external noise and to a second level representative of a sensed cardiac activity; a capacitance coupled to the charging means and responsive to the difference between the first and second levels; and means for generating a pulse generator reset signal, wherein the reset signal generating means includes inert means for limiting the repetition rate of the reset signal; D. An improvement in a demand-type cardiac machine-based device of the type having means suitable for connection to the heart for sensing visceral activity.

(22) The device according to item 21, wherein said charging means comprises rectifier means.

(23) The device according to item 21, wherein the charging means and the reset signal generating means have differential boosting means.

(2) The device according to item 21, wherein the differentiating means has active circuit means.

(25) The device according to item 21, wherein the differentiating means includes passive circuit means.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a known demand-type cardiac axillary baser, FIG. 2 is a block diagram of a demand-type cardiac baser using a cardiac signal identification device according to the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 3 is an example circuit diagram. In the figure, 10, 15, 17 are intensifiers, 12 is a pulse generator, 13 and 14 are output devices, 25 is an inverting intensifier, 22, 26, 51, 57 are capacitors, 23, 25,
39, 41, 53, 54, 56, 62, 69 are resistances, 3
6, 42, 48, 59, 65, and 71 are transistors. ]11 Akira 92 vs. 93

Claims (1)

Claims: 1. A demand-type cardiac pacemaker of the type for sensing cardiac activity, comprising a resettable pulse generator and means adapted to be connected to the heart, wherein the pacemaker is connected to the sensing means and sensed by the sensing means. differentiating means for generating a signal having an amplitude and a repetition rate representative of the sensed signal; capacitance means connected to said differentiating means and said capacitance means also sensed to a first reference level representative of the sensed repetitive external noise; means for charging the capacitance to a second level representative of cardiac activity, the pulse generator being connected to the capacitance charging means and responsive to a difference between the first reference level and the second level when the difference exceeds a predetermined value; A demand type cardiac pacemaker comprising means for generating a reset signal, said reset signal generating means comprising inactivation means for limiting the repetition rate of said reset signal.