JPS5969081A - Rapid signal output means directly connected to living body stimulating apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an output stage for a biostimulator, and more particularly to a directly coupled output stage for outputting rapidly changing signals such as those generated by a cardiac pacemaker. .

In a typical cardiac pacemaker, one or λ
Charge is stored on one or more capacitors. When a pacing pulse is desired, a charge storage capacitor is connected in series with the stimulating and neutral electrode leads and the capacitor is discharged through the leads and the electrode/electrolyte interface into the patient's tissue. (Generally speaking, it is not necessary for the electrodes to be placed in close proximity to the heart tissue, but at least one is necessary.

) A capacitor connected directly to the stimulation electrode lead recharges through the battery power and the stimulation electrode. It is a generally accepted design goal that no net charge is output to the heart. Since the average current through the capacitor → J° is zero, providing an AC coupling is a stimulus'
ili,' Guarantee that there is no 1 d passing through the koshiki.

In those using this type of AC coupling, at least a
There are two main drawbacks. In addition to the fact that the value of the coupling capacitor is 100% higher, the seventh one is bulky, has a force of 8, and is of great importance. This is not a serious drawback in the case of biological stimulators (cardiac pacemakers, or those in 1112). Other drawbacks include stimulation of external biological tissue. Equally applicable (external spines OK,
Devices F and C; are external to the living body, but refer to devices that provide signals through leads inside the living body. ) Electrode leads, at least in the case of cardiac pacemakers, are used to sense electrical activity in the heart. The potential on the stimulated snoring pole changes rapidly at the onset of the pacing pulse;
When the capacitor connected to the electrode recharges, its potential gradually returns. During this charging process the cardiac operating signals are masked. Typically, the potential of the stimulating electrode with respect to the neutral electrode (ground) is a few 100 millivolts during charging → no cycle, whereas the cardiac impulse produces a signal of only a few millivolts, lJ volts. It only brings. Filters used with typical cardiac pacemaker sensing circuits are designed to block charging current signals while minimizing signals that affect cardiac operation. At the beginning of the sensing cycle there is a normal 111 dead period, immediately followed by the generation of the pacing pulse.

During this period! It lasts 10o milliseconds from i0, and may even be longer. This problem is not particularly serious in the case of single-room shakedowns. This is because the cardiac motion was to be ignored by the sensing circuit during the cardiac refractory M, which is at least as long as the dead period. However, the problem is more severe in the case of a two-chamber pacemaker, where completely independent pairs of electrodes are not provided for each chamber, and the electrical activity in one chamber is different from the other. It must be detected shortly after the chamber is pulsed. In such a case, in order to reduce the dead period, the following steps should be taken: 1. The f light's quasi is important.

It should be understood that there are tissue stimulation devices that have a directly coupled output stage. For example, a skeletal growth stimulator uses direct current to the fracture site where skeletal growth is to be stimulated.
Gives a current. Obviously, a direct current output stage is essential in this case. The tissue stimulators involved provide rapidly changing signals, with any signal (AC, pulse, etc.) changing appreciably (with biological effects) within 70 seconds. A typical stimulator of this type is a cardiac pacemaker, in which stimulation pulses are generated every second or so.

The general object of this invention is to provide a directly connected output stage for a rapid A biostimulator, thus eliminating the need for coupling capacitors and eliminating the disadvantages associated therewith. That's true.

Despite the above-mentioned disadvantages of using a coupling capacitor, omitting an output coupling capacitor is almost considered heretical, for example in the field of cardiac pacemakers. For example, 'I'he American Journal
al of Cardiology) / 976
See "Pacemaker Failure Characterized by Continuous Direct Current Leakage," by Fisher et al., June 2013. The belief that coupling capacitors are essential is so deeply ingrained in the minds of cardiac pacemaker designers that even today there is little clear thinking as to whether a capacitor is actually necessary. It has not been done. Careful analysis, however, raises the question not only of whether a coupling capacitor is necessary, but also of whether it really does even the job it is supposed to do.

In any biological stimulator with rapid signals, the stimulation electrode is as close to the tissue to be stimulated as the 41r! Embarrassed. A neutral electrode is implanted near it, or in tissue distant from it. However, the signal current necessarily flows between the two electrodes. What happens here is that the electron current in the electrode is converted to an inocurrent at the interface with the biological electrolyte (the biological fluid is usually a salt). The equivalent impedance at the liquid interface is not the same as that between the lightning poles itself, and the latter can be expressed as a separate resistance. At the interface of each electrode the impedance is actually a distributed Re network, with an infinite number of resistors connected in series and an effective capacitor connected in parallel across each resistor. This is the equivalent circuit through which the pacing current pulse flows and the allocated capacitance charges.

There should be no net charge transfer to the tissue to minimize electrochemical effects.

This requires that the charge accumulated at the electrode/electrolyte interface be recovered. By ensuring that there is no net current flow, the coupled capacitor →'s theoretically results in total charge recovery.

However, since the coupling capacitors are in series with the capacitor, the knowledge of zero net current through the electrode leads is not really important. Theoretically, charge is stored within 8% distributed at each electrode/electrolyte interface, and this 113. The charge is recovered after the pacing pulse as a charge storage node is recharged through the battery and current flows in the opposite direction through the electrode leads. However, just because there was no net current through the bound continuum does not mean that ion flow did not occur within the stimulated tissue.

In a theoretical novel, consider the case of a 7 second, 70 milliampere current pulse output through an electrode. Assume further that the flow of current in the opposite direction can be operatively controlled to cause the same period of time and the same salmon.

A symmetrical square wave current signal flows through the electrodes, where the average current through the coupling capacitor is zero. The current is 7
When flowing in one direction, charge is stored in distributed capacitors at the electrode/1M liquid interface. However, this charge does not remain there until it is collected by a current flowing in the opposite direction. Instead, some charge leaks in the distributed capacitor, flows through the biological tissue, and is irretrievably lost. When the same current pulse is made to flow in the opposite direction, the charge remaining on the distributed capacitance is recovered. However, some of the original charge leaks out and the remainder of the recovered charge must be extracted from elsewhere within the tissue. The net current through the coupling capacitor is zero, but there is actually a flow of two non-heavy ions within the tissue. Seven of them are due to inherent leakage, and the others are due to recovery that compensates for the lost charge. Although the initial leak is undesirable, nothing is lost by mixing the problem with additional ion flow through the tissue. Any damage caused by leakage is not covered. Instead, a guaranteed ion flow will cause more damage. The net charge flowing through the coupling capacitor is zero, but there is no net ion flow, so the charge transfer is not 70. This is a bad case of not actually doing the right thing.

In summary, the best possible "charge balance" (minimum net charge transfer) within the tissue is not necessarily affected by zero net current flow through the electrodes.

Consider another example in which no coupling capacitor is used, ie the output stage is not connected in series with the electrodes. The example illustrates the principles of the invention. A typical regular d-period pulse is 10 milliamps in volume.

O0 left has a duration of milliseconds. Assume that instead of allowing the coupling capacitor to be precharged through the electrodes to an integral value equal to the product of current hour, i.e. S milliamps-milliseconds, the electrodes 1 are connected to each other by /1(j). Experiments have shown that qq% of the charge output through the electrode during the pulse is recovered during the first g milliseconds via the lead following electrode shorting. means that the net current flow in the tissue is only about 1/2 of the peak pulse current.

If a coupling capacitor is used, charge recovery is relatively slow because the coupling capacitor typically returns to the battery power supply through a resistor. During a relatively long charge recovery time, e.g. 700 ms, the allocated '4%
- some of the charge on (′i leaks out, hence this force 1
The charge can simply be recovered by additional ion flow within the tissue at the end of the charge recovery (iM) phase. It is the capacitor itself that produces this non-heavy ion flow, the reason being that the only way to achieve zero net flow through the capacitor is to recapture the charge that leaks out of the apportioned chamber. This is because an additional ion flow is generated. However, if the lightning single pole leads are shorted together, the capacitance distributed across the short will rapidly discharge. The discharge is so fast that approximately 99% of the charge is recovered within g milliseconds, as in a duplicate. Although approximately % of the charge leaks out of the distributed capacitance and adds to its damage, it is only because the distributed capacitance discharges 1 that it leaks less because it is rapid. The damage is not compounded by the fact that a totally unnecessary ion flow occurs in the opposite direction.

In this case, do not short-circuit the electrodes for more than 8 milliseconds.
There is no compelling reason to keep it that way. Never more than 99% of the initial charge is recovered, and the initial g
Approximately 1/2 of the initial charge does not leak out and be recovered during 1J seconds.

The current flowing in the opposite direction drops to a low level by the time g milliseconds expire. There is no reason to leave the electrodes shorted for any longer than this, although they do not cause any harm as short terminal electrodes do not create unnecessary ion currents (charge recovery is passive, not active). do not have. This means not only avoiding the use of expensive and large coupling capacitors, but also greatly reducing dead periods (in the context of cardiac pacemakers).

(As soon as the ground fault circuit, the mechanism used to couple the electrodes together and allow for the dissipation of the passive load, is opened, the electrodes can be used to sense the movement of the heart; The resulting signal is not masked by the flow of charging current on the output capacitor →)' (although a voltage component at the interface still remains due to unrecoverable charge).

Of course, the electrodes remain shorted in this manner for more than 7 milliseconds, providing an automatic refractory period of the desired duration. In a typical LB ventricular inhibited (VVI) cardiac pacemaker, the sensing circuit may be activated after the pacing pulse is generated. ;
It should not respond to cardiac motion for about 0::IJ seconds, and a short circuit that recovers charge is a convenient mechanism for disabling the sensing circuit. Generally, the present invention contemplates shorting the electrodes for 0.01-11-00 milliseconds. For short periods at the lower end of the range, 8. Especially in the case of cardiac pacemakers, g
A short-circuit pause period of -J-O-IJ seconds is preferred.

The invention is particularly useful when used in implantable devices where it is desired to eliminate some elements such as large capacitors. It should be appreciated that this invention is highly effective in the case of typical cardiac pacemakers where only one voltage source is provided. λ of opposite polarity
It is conceivable that if two voltage sources are provided, the use of a coupling capacitor can be avoided by switching the two voltage sources to the stimulation electrodes. One voltage source is used to control the application of pulses to the stimulating electrodes.

The other voltage source is then used to control the actual discharge of the allocated capacity. However, common cardiac pacemakers are not provided with two voltage sources. It has been believed that only one polarity voltage source is used and a coupling capacitor is safe for charge balancing purposes. For the reasons mentioned above, the capacitor is in fact not needed;
O All this does not mean that the use of capacitors can be avoided, even undesirable. In fact, in the illustrated embodiment of the cardiac pacemaker of the invention, 1.2 large capacitors are used. One capacitor, typically S~/3/IF, is connected across the battery in the manufacturer to [E (?y) to stabilize the J line. This capacitor has nothing to do with pacing pulse output or charge recovery, and is used only to ensure that transients resulting from the pacing pulse do not affect the energization of other circuits within the pacemaker. do.

The λth capacitor, typically /! ;IIF stores the actual charge to be output during the application of the pacing pulse.)
It will be recorded in history. The normal battery used in cardiac pacemakers is 1. It is not possible to supply the relatively large current required by the current circuit.

A common technique for obtaining this relatively large current is to charge a storage capacitor from a battery and then rapidly discharge this capacitor into the electrode leads whenever a pacing pulse is desired. Although this invention uses such a capacitor, it is not a coupling capacitor. This is because although the coupling capacitor outputs the pacing pulse directly to the stimulation electrode, no charge is recovered through it at the end of the pulse. The capacitor does not recharge through the electrodes between pacing pulses. Rather, the capacitor charges seven more times in preparation for seven more pacing pulses through circuitry within the pacemaker, and current flow through the electrode leads is not involved. Charge balance is achieved by shorting the two electrode pentodes together.

The storage capacitor acts as a coupling capacitor because all the current flowing through the stimulation lead does not flow through it.

Ordinary conventional heart pacemaker is often 1u I
Contains CE circuit. Such a circuit results in the use of two large storage capacitors (in addition to the third filter Contin'IJ across the battery). These λ capacitors are charged separately to a potential of
One contin day no ° (1 bound conden 4 no,
It is charged through the discharge electrode lead for charge coupling. When a pacing pulse is required, and if a double amount of pulses is superimposed, two capacitors are connected in series with the electrode leads. In the illustrated embodiment of the invention, a voltage doubler is also provided. However, instead of using two large storage capacitors of 30 μF,
The components of SμF are typically 0. A small pump capacitor of /1 tF and -hN is used. The pump capacitor controls the potential of the storage capacitor equal to one time the battery power supply. The net result is therefore that seven large capacitors are omitted.

This means that the size has been reduced to half of the other size. However, although two large capacitors were used to achieve the voltage doubler, one of them was not used to control charge balance.

Unwanted ion flux in living tissue is avoided. In other words, there is no net decrease in components.

From a physiological point of view it is good to provide a direct connection, not least because the use of a free-flow connection makes it possible to considerably reduce the dead period.

In seven experiments conducted in the past, the electrodes were 1.
/ IJ was placed in a saline solution to simulate living tissue. o,s msec, 10 mA pulses were generated at a repetition rate of l/s, and the net current in the lead was measured by the amount of different short-circuit rest periods following the application of each pulse.

The table below shows the net current, ie the charge imbalance, for different short-circuit rest periods.

Short-circuit rest period Net current / ms /,? 0μA7.
73 milliseconds 0.62 μA milliseconds
o, ylIμAノ, 73 ms
0. /! ;μA31.2 milliseconds θ, 73μA, Tami milliseconds θ, oqμAg milliseconds
A further object of this invention to θ, θri μ,
Features and advantages are listed below in connection with one drawing.
This will become clear if we consider the following explanation.

The output stage of the conventional pacemaker of FIG. 1 includes a 3 volt voltage source 72 and a filter contin →jAg connected across it. Two voltage buses for energizing the base maker circuit are shown Vt and V-. Capacitor Ag is typically s~/μF, and its use, as discussed above, is necessary for reasons other than pacing pulse output or charge balancing.

The other portions of the circuitry shown in FIG. 2 are output stages themselves; the circuitry for sensing cardiac activity and synchronizing the pacing pulses is not shown. During the pacing pulse the two transistors /l and /q are kept off. Capacitor /S is resistance /3 and /7
Through λ, two voltages IU are charged between the lines. The right side of the capacitor becomes sufficiently negative with respect to the left side before the need arises to generate another pacing pulse. At the same time, the capacitor is charged by 4 J (anti, 23°) through the stimulation and neutral electrode leads, the two electrodes, and the heart tissue. At the electrode/electrolyte interface, the charge is recovered from the distributed capacitance. It is during this period that the left side of capacitor 2 is charged to a negative voltage with respect to the left side.

Zener diode 70 is a common protection diode to prevent excessive voltages across the 1. two electrodes and does not need further explanation here. When a pacing pulse is to be output, a positive pulse is applied to the base of transistor //. That transistor turns on, shorting the left side of capacitor /S through it to the negative voltage bus. This negative voltage step is caused by capacitor 2
through the left to the generator of transistor/7,
This transistor /9 is also turned on. Capacitors /S and CO are now connected in series between the neutral electrode, the pole IND, and the stimulating electrode STIM, and a negative pulse is applied to the stimulating electrode to pace the heart.

At the end of the pulse, transistor l/ is turned off, with transistor /? is also turned off. capacitor l
Now recharges through resistor /3 and 17 and capacitor 2S; ji through resistor /3 and heart tissue. (Resistance, 2J, is typically kiloohm.

It should not be too large, otherwise it will take too long for the condenser S to charge. ) This technique of charging each of the capacitors to the full supply voltage and then connecting them to the iM string when the pacing pulse is about to occur increases the amplitude of the pulse to a factor of 7 that of the battery. do. Each of the capacitors /S and 2 has a size of 30 μF, and one capacitor is connected in series to output the pacing pulse.
! The capacitance is equivalent to r 1tF.

Capacitor 2 left serves two functions. First, it is the keyhole L that is used so that one of the two storage capacitors achieves voltage multiplication and stores sufficient charge for large current pulses. The third point is that the capacitor 2S is used as an AC coupling capacitor. Since the net current through the capacitor must be zero, the net current flow through the electrodes is necessarily zero. ”
As a duplex, however, it does not provide charge balancing, despite the fact that a coupling capacitor was considered necessary. In fact, at each electrode/electrolyte interface, perfect charge balance is not possible due to leakage from the distributed capacitance, and the condenser , produces the necessary ion flow. By controlling the amount of net current to zero, "[produces] a net transfer of charge that is greater than otherwise."

The capacitor, 2 left, may be needed for other reasons, i.e. if the switch ink transistor in the pacemaker fails in preventing continuous DC voltage from being applied to the stimulating voltage. Conceivable. However, switches are usually more reliable than capacitors, especially in integrated circuit pacemakers.

Although the pacemaker of Figure 1 is shown more specifically than the conventional pacemaker shown in Figure 2, and all of the components necessary for pacemaker operation are shown, they are Some of the components are well known to those skilled in the art and are therefore shown in blocks. Stimulating and neutral conductors 41snM and ND are connected to leads 6 and 61/-, respectively. A Zener diode 70 similar to C is placed across them. Unlike the resistor 23 in Figure 2, the °C1 resistor A is a high impedance element, typically 10 OK ohms, and it is not used to recharge the storage capacitor. Capacitor All of FIG. 1 performs the same function as capacitor 6g of FIG. 2; it is a filter capacitor for a 3 volt power supply. Capacitor 3 in Figure 1
Reference numeral 6 is a moss Wc''n, which causes a pacemaker pulse to be output when it discharges. All of the charge applied to the stimulation rod is output from this capacitor 3A.

Therefore, in the conventional circuit shown in Fig. 2, two 3θμF
Capacitors /left and 2 left are used to give a series capacitor equivalent to /SμF, but capacitor 3
B simply requires /SμF. This capacitor 3B is charged to twice the battery voltage, as explained below, and outputs a stimulation current pulse of the same shape as the two 3θ μF capacitors in the circuit of FIG.

The capacitor 3θ in FIG. 1 is a very small pump capacitor of θ,/μF. As will be explained hereinafter, this capacitor has a voltage dimension equal to twice the supply voltage.
1 bottle is used to inject 6.

Amplifier yg is a common sense amplifier that responds to electrical activity within the heart, which detects natural heart beats. The output of timer SO is normally low. The pacemaker is
Affects the "C" request (VV emode) in that the pacing pulse is generated only when requested. If timer SO is adjusted to provide a pacing rate of 60 heart beats in 7 minutes, the output of that timer will be as low as \1 as long as a natural heartbeat is detected at least once every second. Stay in. However, whenever one second passes without a heartbeat occurring, the output of timer 5θ goes high for O,S milliseconds.

This results in the generation of a pacing pulse.

As long as the heart beats normally and the output of the timer SO is low, the output of the inverter /4' is at a high potential and the output of the inverter /4' is at a high potential, enabling one input of the NAND gate /2. The input of is connected to the oscillator io of /KH2. Therefore, the output of gate l is alternately pulsed at high and low potentials at a rate of /KHz. When the gate output is at low potential , transistor θ is kept on, and transistors /J'A and /gB are kept off. These latter two transistors /gA and /gB are equipped with ordinary transmission gates and are connected to the inverter. /6 are controlled to give opposite potential levels to their gate terminals. The output of gate 7.2 is also connected to the input of a level translator tag θ. When the output of )/- is at a low potential, it acts to output a low potential at its output. Therefore, when transistor 20 is on and transistors /ffA and /gB are off, the level translator and inverter 'it2 is transistor 3.2A and 3
．． Leave 2B on and go [transistor? &
Let A and 311B be off at t'>. Therefore, current flows from the positive power supply PJ line through transistor θ, capacitor 30 and transistor 321.32B to the -C negative bus, charging capacitor 3θ, and the left side of the capacitor becomes °C positive with respect to the right side. Become.

The only reason for providing the level translation rake qθ is that in order to completely turn off the N-channel transistor JFB,
This is because the gate must be kept at the most negative potential in the circuit. The most negative potential is not necessarily ■−
It is not the potential of the bus bar. This is because the capacitor 3 charges up to 1 times the battery power supply, and the lower side of the capacitor becomes more negative than the negative bus line V-[. Therefore, the potential on the lower side of the capacitor 3B is expanded by the level translator 290, and when the output of the NAND gate/2 is at a low potential, the output of the level translator is equal to the negative potential input of the two negative potentials, that is, - It is always the lower of the potential or the potential of the bottom side of capacitor 36. When the output of NAND game) 7.2 is at a high potential,
The output of the level translation tag θ is equal to the potential of the V0 bus.

The output of the level translator and impark 412 is a device that includes a transmission gate, ? lIA and 3+
B is kept off, then the device 32 containing the transmission gate
A and JJB are on.

Therefore, while charging the capacitor 3θ, the capacitor, ? θ
is not coupled to capacitor 36.

During the alternating current cycle of oscillator operation, the output of Gate/J is at a high potential. The high potential applied to the gate of device θ keeps the device off. At that time device 3
Core A and J2B are also off and conducting are Denox/gA, IgB, 3gA and 39B.

As a result, there is a series connection between capacitors 30 and 36 between the + and V- buses, and the transmission gate force. The charge on capacitor 30 is transferred to capacitor 36 and the voltage across capacitor 36 increases. The rise is step-like. Capacitor 30 is charged during an AC half cycle of operation. During these cycles the charge on capacitor 30 is transferred to capacitor 3B.

Capacitor 30 is always charged such that its left end is positive with respect to its right end, so that the charge on capacitor 3
Each time the capacitor 36 is output to A, the lower end of the capacitor 36 becomes negative with respect to its upper end. The voltage change across capacitor 36 becomes smaller and smaller as capacitor 36 charges, but in much less than one second capacitor 36 becomes charged to one time the battery power.

When the sense amplifier circuit determines that a pacing pulse is required, the output of timer θ goes high for θ, S milliseconds. The output of the inverter/F becomes a low potential, and then
[The 111 force of gate/, 2 becomes a high potential. This in turn brings the output of the level translator IO to a high potential, enabling one input of gu)<zp. gate lll1
．． The other input of is connected directly to the output of timer SO
Therefore, the output of V+ is θ. High potential for S milliseconds. The output of its gate 4 (& is the transistor 3g
Since the transistor is connected to the gate of the device 3, this transistor conducts and the charge on the °C storage capacitor 36 is transferred to the device 3.
g to the stimulating electrode, current flows through the heart tissue and the neutral electrode to the −[V+ supply. capacitor 36
The duration of this pulse, which is the time during which is discharged, is 0.5 milliseconds, since that is the period during which the output of gate lI4/ is at a high potential. It should be noted that transistor 3g is a SON device, which means that its on-resistance is so far less than the on-resistance of other possible transistors, by a factor of SO. When stimulation pulses are to be delivered to the patient's heart, a very low resistance in the electrode leads is required, and for this reason the transistor, 7g, is a large device.

During the time that the pacing pulse is being output, the output of the gate is at a high potential. Therefore, the continuor 36 is not only connected to the stimulation electrode lead via the transistor 3g, but also to the transmission gate, 3'lA, and the JgB1 capacitor 301.
It is also connected to the negative power supply bus through the transmission gates /gA and /gB. However, this is not important.

Because it's stimulating! This is because only negligible current is directed from the pole to capacitor 30 due to the relatively small size of capacitor 30.

Pulsar q6 is triggered on the trailing edge of a positive pulse of o,s milliseconds applied to its input. When the pulser is triggered, it generates a negative pulse, and the duration of that negative pulse controls the duration of shorting the electrodes A & AA, which discharges the distributed capacitor at the electrode/electrolyte interface. The charge stored in can be recovered. The output of the pulser is applied to the gate of transistor 6θ, and the device turns on when the pulser output goes to a low potential.

Transistor 1.0 is also thick, has a very low on-impedance, and has a fast dissipation, i.e. recovery of the allocated capacitance, through the shorted electrode leads. As soon as the pulser output reaches a high potential, transistor AO turns off. The period of electrode lead shorting is independent of capacitor 36 recharging. At the end of the O,S millisecond pacing pulse, the output of gate II1 is at a low potential, so transistor 3g is turned off. This isolates the two electrode leads from the rest of the circuit and prepares the capacitor 3 for another pacing pulse.
Start charging θ.

It should be noted that while the two electrode leads are shorted together, the sense amplifier sg is inactive.

Although not shown, this amplifier is responsive to a potential difference between the stimulus and neutral leads, and sensing operation is disabled while the straws are shorted together. An absolute refractory period of approximately 100 milliseconds is desired in a typical demant pacemaker. The sense amplifier should not detect cardiac motion (actl, vity) resulting from the stimulation pulse itself, nor should the stimulation pulse be detected or interpreted as a natural heart beat.

Refractory period control is 1' automatic in that no additional circuitry must be provided to disable the sense amplifier while the leads are shorted together.For a typical VVI base manufacturer, the pulser & The pulse duration at the output of can be adjusted to be as high as 300 milliseconds. In other cases where a short refractory period is desired,
Pulses should be shorter. ” g like two in a row
Pulses on the order of milliseconds effectively result in total charge recovery.

The importance of a low 1"on" impedance for transistor A should be appreciated.

Even if the transistor is kept on for 3θθ milliseconds, it is necessary to quickly recover the charge. A problem with conventional pacemaker circuits, as mentioned above, is that during actual charge recovery, there is leakage from the allocated capacitance, and the leaked charge is not recoverable. Conventional circuits unnecessarily create opposing ion flows that serve no practical purpose other than controlling zero net current through the electrodes, which is not useful in itself. In the circuit of Figure 1, the charge balancing process is passive (electrode shorting) rather than active, so that no charge leaks out of the distributed capacitance at the electrode/electrolyte interface, and the opposite ion While not unnecessarily compensating for flow, it is also desirable to minimize charge leakage. For this reason, most effective shorting of the electrode leads is desired, and this is achieved by providing a very low 6 on'' impedance to the device AO.

Both switches 3g and 10 are 1 below 200 ohms.
These switches, like condenser bombs, should have a "on" impedance.
6 rapid (i) filed on the same day as the present application by a person
Inc. 1 ゛ 1 number is described in more detail in the name of the name of the name of the Interview and Interview Auto for the Biological Stimulation device, and the application is incorporated as a reference in this application statement. .

Although the invention has been described with respect to a particular embodiment, it should be understood that this embodiment is merely illustrative of the application of the principles of the invention. Many modifications may be made and other devices may be devised without departing from the spirit of the invention.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a cardiac pacemaker according to an embodiment of the present invention, and FIG. 1 is a circuit diagram partially showing the output stage of a typical conventional AC-coupled pacemaker. In the figure, /θ is the generator, lJ is the N A N i) gate, /g, /A and 41, λ is the inverter, tgh
,1gB,,2o,y,2A,JλB. JIA, 3 (IB, 3g and 6θ are transistors, 3
0゜3A and 6g are capacitors. 7θ is a Zener diode, and 7λ is a voltage source.・---jJ

Claims (1)

[Scope of Claims] (1) Connected to a battery power source, a pair of electrodes for transmitting stimulation pulses to the patient's heart, and at least one electrode for sensing cardiac movement. a sensing device connected across the electrode, a storage capacitor device, and a capacitor device responsive to and responsive to the sensing device to determine the necessity of a stimulation pulse; 1)) a connecting device 6 for applying stimulation pulses to the patient's heart JIM; a device for charging the storage capacitor from the battery power source following application of stimulation pulses to the patient's heart; A coupling device operative to directly couple four poles to one another as a result of the stimulation pulse, independent of the battery power source, the coupling device operable to directly couple the electrodes to each other as a result of the stimulation pulse, independent of the battery power supply. and a cardiac pacemaker capable of recovering a large portion of the charge accumulated at the interface between tissues of the patient through the electrodes. (2) The cardiac pacemaker according to claim 1, wherein the coupling device operates for a period of time in the range of 0.07 to I10θ milliseconds. (3J Mf connection device removes the storage capacitor device from the electrode at the same time as the operation of the 11 connection device,
Therefore, while the charge stored in the patient's heart is being recovered through the electrodes, the storage capacitor device can be charged from a previous battery. Heart pacemaker described. (4) The cardiac pacemaker according to claim 2, wherein the coupling device W shorts the electrodes together. (5) supplying a stimulating current to the patient's heart; a polar device; a sensing device for sensing the movement of the heart; and responsive to the sensing device +gt to determine the necessity of the stimulating current; and a control device responsive thereto for causing a stimulating current to flow through the electrode device;
A cardiac pacemaker comprising a device capable of operating in a controlled manner. (6) A cardiac pacemaker according to claim S, wherein the Loeto device is operated for a time period within the range of 0,0/-1100 milliseconds. (7) Track 11. A cardiac pacemaker as claimed in claim S, wherein the electrode arrangement consists of λ electrodes, and the enabling device is operative to short-circuit the electrodes of the front RI2 together. 8. The cardiac pacemaker of claim S, wherein the pacemaker is energized from only one source of pen pressure, and wherein the flf control device is operative to cause current flow in only one direction through the electrode device. <9) The cardiac pacemaker of claim S, wherein an i+I *i4 sensing device is connected to the electrode device and is disabled from sensing cardiac motion while the enabling device is operating. (Claim 9) The device capable of recording 10Ail is operated for a period of time in the range of θ, ol-yoo milliJ seconds.
Cardiac pacemaker as described in Section. Oυ front'''I electrode device consists of two electrodes.
10. A cardiac pacemaker as claimed in claim 1O, wherein the 7-enable device is operative to short the two poles together. 02 The pacemaker is energized from only one voltage source;
A cardiac pacemaker according to claim 1, wherein said control device is operative to pass current in only one direction through said electrode device. A biological tissue stimulator for applying a rapidly changing signal to a site to which a small net charge of O* tV is to be transferred, the device comprising: an electrode arrangement for applying a stimulating current to said site; and a rapidly changing direct coupling; a control device for causing a stimulated current to flow through said 'electrode device'; and, following operation of said control device, receiving 1d of the apportioned volume 1d at said site;
A biological tissue stimulator comprising: a device operative to enable kJJ) jk electricity; 04 The enabling device is operable to open for a time 1υ1 within the range O0θl-700817 seconds.
/ ,? +, biological tissue stimulator described by the member. θi the electrode device consists of a pole; the i1
The biological tissue stimulator according to claim 1J, which operates to short-circuit the one electrode to each other. The biological tissue stimulating device according to claim 13, wherein the biological tissue stimulating device operates to flow a flow of one color in one direction through the polar device. Dress! 9 is s
A biological tissue stimulation device according to claim 1, which is inoperable while the fftl-recordable device ρ is in operation. (+Pj rlif Aself'N Ml Tomoe device'g, is 0.0 / ~ II 00 milliseconds) Stone 1) Biological tissue stimulation according to claim 17, which is operated by opening the time period of the concave circle. Device. 0L1) The biological tissue stimulation device according to claim 1, wherein the electrode device comprises λ electrodes, and the enabling device is operative to short-circuit the λ electrodes to each other. 20. The biological tissue stimulator of claim 19, wherein the stimulator is energized from only one source of pressure, and the control device is operative to pass current in only one direction through the electrode device. QD: to stimulate a site where a low net charge transfer is desired, a pair of electrodes for passing a current through the site, a charge storage device, and a charge storage device to stimulate the current when the current is to be output. An output circuit for a biological tissue stimulation device comprising: a connecting device connected in series with the pair of electrodes; and a coupling device coupling the pair of electrodes to each other following operation of the connecting device. (c) The connection device connects the charge storage device and the tW.
, 4′! 28. The biological tissue stimulation device according to claim 27, wherein the coupling device couples the other of the electrodes to a connection point between the connection device and one of the electrodes. Output circuit for. (c) An output circuit for a living tissue stimulation device as claimed in claim 11, wherein the coupling device is open for a time period within the range of 0.0/-4100 milliJ seconds. (c) The pre-stimulator is energized from only one voltage source, and the charge system 4t device is connected to the electrode only when current flows in one direction through the electrode.
+i) An output circuit for the biological tissue stimulation device according to item 23. Q.9. The stimulation device is energized from only one voltage source, and the storage device is connected to the electrode only when current flows in one direction through the electrode. Output circuit for biological tissue stimulator. (c) The Mjl coupling device is o, oy-aoo mi 1
An output circuit for a biological tissue stimulator according to claim 4, which operates over a period of time in the range of seconds. (b) The i'lil i queen stimulator is energized from only one voltage source, and the charge storage device is connected to the electrode only when current flows in one direction through the electrode. An output circuit for the biological tissue stimulator described in λ/.