DE2150144A1 - Pacemaker - Google Patents

Description

FATE TfTANVTA. X. T

Din * ing. E. HOLZEB 89 AUGSBURG

»HJXIPPINB-WKI-SKB-STRASS» 1 «

W.552

Augsburg, the β. October 1971

Medical Electronics Research Corporation,

5920 Rodman Street, Hollywood, Florida 53023,

V.St.A.

Pacemaker

The invention relates generally to pacemakers and, more particularly, to implantable, demand-only pacemakers electronic pacemakers with a long lifespan.

Currently, the lives of thousands of cardiac patients are sustained and prolonged by pacemakers,

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which supply the ventricle with artificial stimulation impulses, when the heart is unable to make ventricular contractions to be carried out with a normal pulse rate.

With pacemakers a distinction is made between continuously working pacemakers on the one hand and only when necessary working pacemakers on the other hand. The continuously working pacemakers generate a continuous one Sequence of artificial cardiac stimulation impulses with a normal frequency of 60 impulses / min · to 85 impulses / min, Die On-demand pacemakers create a "ventricular contraction." evoking? artificial impulse only if there is no normal ventricular depolarization or if it does is irregular.

Older examples of on-demand pacemaker systems are from GB-PS 826 766 and from US-PS 3,345,990 known. However, these older systems are fundamentally not implantable, they are too heavy and too big and do not have a long service life without maintenance. The transistor and modern batteries have made the implantable pacemaker possible, examples of which Continuously operating, implantable cardiac pacemakers are disclosed in US Pat. Nos. 3,057,356, 3,109,340, and 3,474,353

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and 3,518,997 known. More recent cardiac pacemakers are known, for example, from US Pat. Nos. 3,253,596, 3,431,912, 3 ^ 33 and 3,478 IkS.

When using implantable cardiac pacemakers it is also required that they have a low power consumption and work extremely reliably over a period of several years, both with regard to the operation of the electronic circuit and with regard to the durability of the portable energy source. In addition, a simple and A reliable device for determining the exhaustion of energy in the portable energy source or _a battery should be provided. In addition, the pause between artificially generated impulses should be able to be controlled in such a way that it is independent of a variable cardiac load. Known cardiac pacemakers, however, have so far not been in a manner that welefee fulfills all of these requirements. However, all the desired properties should be combined within a pacemaker, which would have to have a single, redundant, low-voltage battery and at the same time be so small and light that it could be plowed into the body.

With known cardiac pacemakers there is no s & rcu-

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electronic refractory phase is available, which is a long refractory period to prevent resetting of a clock generator during electrical stimulation of the heart and a includes a short refractory period to adapt to premature ventricular contractions. With only a short, simulated refractory period it is possible to change the timing of the artificial cardiac stimulus. With just one long, simulated On the other hand, the refractory period can be continuous in the case of tachycardia, i.e. with very fast heartbeats r artificial irritation occur.

The invention aims to achieve the object of creating an on-demand pacemaker, which in the implanted state has a very long service life and high reliability and with a redundant, portable low voltage power source is provided, which is also long life and high Has reliability “In addition, the pacemaker should maker with low power consumption and as an on-demand pacemaker have a variable refractory period, and in the presence of high frequency noise continuously deliver artificial impulses, but at a normal heart rate up to and including tacbycardia block the generation of artificial impulses. The pace

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Macher should also use a pulse generator with lower Have power consumption, which the pulse pause and the pulse duration in the event of changes in the pulse load keeps essentially constant »After all, the pacemaker should have its own display device, so that the battery condition can be easily determined.

In order to achieve this object, the invention includes a cardiac pacemaker which is characterized by a r ticks divisible pulse generator which, after a certain pause after its reset, generates an artificial cardiac stimulus, furthermore by a De "i> tii <: tor: uihaLtimt ; for detecting an artificial or natural cardiac stimulating pulses representative signal further by el: ^t:;! '- "inlTitellschaltung which depending on cine n Teat ;; eateilten natural H-rzreizsignal resets the pulse generator, which upon generation of an artificial cardiac stimulation pulse resets itself, furthermore by a blocking circuit which divides the reset circuit during a period after the plague; 55 of each natural oA & r <\ artificial herx; re-; ^: prevents iigrialo from resetting the pulse generator, and only by means of a portable electrical energy source, the -jn output voltage

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lower is also that for artificial heart peeling required voltage,

The pacemaker according to the invention has in its preferred embodiment has a low weight and high reliability, eats implantable, and is reduced by a portable redundant power source If the voltage is supplied, it takes a very weak one

^ Electricity and still meets all important requirements, Ψ

that are placed on an on-demand pacemaker, including an adjustable refractory period and one continuous irritation in the presence of high-frequency noise or in the case of tachycardia. The pacemaker after the invention is provided with devices by means of which the state of the energy source by its own Switching operation can be read out externally and delivers a controlled pulse width regardless of whether it is left or not and pause.

The pulse generation and the timing control of the pulse pauses is connected in the pacemaker according to the invention by capacitor charging and discharging cycles achieved with a feedback switch, which is in the Feedback branch of a pulse width control device is switched »The pacemaker according to the invention

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has devices for sensing every artificial heart stimulus and every natural heartbeat signal the heart chamber and to reset the clock control of the pulse generator by the capacitor discharge during Occurrence of every sensed pulse and signal.

During a simulated refractory period, the sensing device prevents resetting of the pulse generator clock control interval. The simulated refractory period consists of two parts, namely a long refractory period during artificial stimulation and a short refractory period v. ^r during normal heartbeat up to and including tachycardia. In this way, natural heartbeat pulses in a range from normal heartbeat frequency to tachycardia keep the pacemaker according to the invention in a ready state. Only when the natural heartbeat is absent or when its frequency falls below a certain value or when a heartbeat with a higher frequency or high-frequency noise is detected does the pacemaker according to the invention generate artificial cardiac stimulation pulses.

The pulse generator of the pacemaker according to the invention has a Ge ^ entakt voltage doubling

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output circuit, which allows the use of a redundant power source low voltage. These low voltage makes the pulse pause independent of the source voltage, which is determined by that the pulse generator uses an external magnet and an internal flow sensitive switch is triggered externally in a continuous pulse mode. Due to a special design of the circuit of the Pacemaker according to the invention, the pulse pause and the pulse duration are controlled.

In addition, the circuit of the pacemaker according to the invention is designed so that this one very has low power consumption.

Several exemplary embodiments of the invention are shown in the drawings and will be described in more detail below described. Show it:

Fig. 1 is an electrocardiogram of a

normal heartbeat,

Fig. 2 is a complete circuit diagram

a pacemaker according to the invention,

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fig, 3 a circuit diagram of a modified

Pulse generator for the pacemaker according to the invention, and

Pig * 4 a circuit diagram of another

modified pulse generator for the pacemaker according to the invention.

Fig. 1 shows the electrocardiogram of a normal heartbeat with a period of 0.86 s, which is a Immediately before the atrium contracted, it produced a P-wave, and also a QRS group signal, which indicates the contraction caused the ventricle, and then has an S-T-Welie. A refractory period lasts after QRS group about 0.3 s. During this time, that speaks Heart does not respond to an artificial stimulus «A susceptible period of very short duration follows the refractory period at. In a diööer period of time an artificial Irritation cause heart damage.

In Pic »2 is a circuit diagram of a complete On-demand pacemaker shown according to the invention, with puncture blocks indicated by dashed lines

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A redundant energy source 12, which has a low voltage, supplies via the upper and lower ones (or grounded) lines 14 and 16 electrical energy to the pacemaker.

Pulse lines 18 and 20 conduct artificial electrical cardiac stimulation pulses from a pulse generator 22 to the heart chamber a heart 24 shown as loading the pacemaker and natural QRS signals from the heart via series capacitors within the pulse generator to a feedback amplifier 26 which has a high gain and draws a low current. Typically, the impulse line 20 is to a plate embedded in the body or to an exterior surface an implanted cardiac pacemaker connected, while the line 18 via a catheter electrode, not shown is in contact with the ventricular muscle of the heart 24.

The pulse generator 22 generates pulses with a duration of 1 ms and with a certain pause of about 86o ms, which elapses between the pulses, provided the generator is not reset and with this

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Pause begins ο Resetting is done by sensing, Amplification and processing of that signal achieved, which then always results on lines 18 and 20, when a natural QRS signal or an artificial stimulus is generated.

The amplifier 26 receives signals which represent the natural QRS signals or artificial electrical cardiac stimulation pulses at an input 28 and outputs these at an output 30 in a highly amplified manner. Separate paths negative DC feedback and negative '.'echselstromrückkopplung within the amplifier 26 serve to stabilize and allow inside the amplifier 26 is a high gain in spite of characteristic changes of the active elements and the power source 12 ₀

The high gain characteristic of the amplifier drives it high into saturation when the input 28 receives large signals, polygons occurring during artificial stimulation. The amplifier 26 is maintained in saturation for a period of time which is considerably longer than the duration of the artificial electrical stimulation pulses input to it. This is the last training ^ _to: issignal from the amplifier 26 through the completion of each

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artificial impulse delayed. Since the natural F.ingang at 28 '.jignalen JRS received signals ala a lower level, the signals of artificial pulses have, the saturation of the V is ar more and 26 is minimal and the signal delay during natural llerzreisung negligible _e This variable oättigungsvei''"'.'.; erun.j of the amplifier 26 forms a substantial part of a simulated refractory period and gives this simulated

Refractory since a variable characteristic. f

?. That signal at the output 30 of the (■> amplifier is input to a Vergleieher 32 which at an output 3 ^ polar a Uni signal outputs indicative of the amount by which multi away the electrical magnitude of the output signal of the Ve-rrAJir] er ;; 2G exceeds a threshold value in the vicinity of a quiescent pe · /, ·] ... 'In output 30 ,,

Hit the unipolar pulse from the output J> k of the comparator j begins the course of a fixed portion of the simulated refractory side. The fixed part of the simulated refractory period is set by a blocking state of the blocking circuit 36

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determined during w _e iChem an output 3NC the latch circuit jC locked. In the short interval between
the input of a unipolar pulse into the blocking circuit J> 6 and the formation of the blocking state, the unipolar pulse appears at the output of the blocking circuit 36, where it resets the pulse generator 22 and the restart of the pulse pause of the pulse generator 22 via a reset circuit HO between the pulse generator 22 and the blocking circuit 36 causes «,

The pulse generator 22 is provided with an internal capacitor ^{charging circuit l} \ 2 for clock control, whose
Time constant defines the pause between the pulses,
liLne discharge circuit 43 discharges the capacitor,
which leads to the generation of a pulse and the restart of the iripulopus. The rucks tel Ljchaltung 40 also causes a discharge of the capacitor when a unipolar signal is received!:;. The Ent Ladestrecke bay /, -ücüaLtung 43, which is used to generate an IiupuL.; It is in the
Rüokkopplurijozweigen a monostable lip pulse width control circuit h ^} \ connected, which controls the duration of the artificial stimulus from the generator 22 and which also the interval between such pulses of stress effects due to changes in the load 2 ^l \ from

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Patient to patient or in the same patient between makes the lines 18 and 20 independent. Finally, a push-pull voltage doubler receives the controlled pulse from the monostable circuit and doubles the size of the output voltage, so that the pulse present between lines 18 and 20 is almost twice as great as that from the energy source supplied voltage.

The pulse generator 22 thus generates when it is not present natural heartbeat signals continued pulses with a certain pulse pause and width, but if a natural heart attack signal is received, the Pulse generator 22 instantly at the beginning of a Pulse pause reset without an artificial pulse is generated unless the natural impulse in question is within a simulated variable refractory period following the last natural or artificial 'Stimulus impulse appears ,, In the latter PaLL the impulse generator not postponed. The fixed pulse saturation;: s components of the refractory period, polygamy, a total of about 350 ms ensure that no signals received by the amplifier cause a reset of the pulse generator ^ effect if they are within a long refractory period

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appeared following an artificial stimulus. The pulse pause therefore extends from the last artificial cardiac stimulus to at least this long refractory period out.

In the case of tachycardia (chasing after), that beats He: ·,: up to 220 times per minute, as opposed to one normal heart rate of 60 heartbeats / min, up to ü! 5 heartbeats / min · VJduring the tachycardia state should no artificial irritation occurs. However, continuous stimulation should take place when at the entrance of the Amplifier 26 noise, Γ-disturbance or heartbeat signals are present, whose frequency is above the tachycardia frequency. the shorter, fixed refractor time, polygamy is about 250 ms long, ■; est. '; Kills up to a - / location of 220 heart beats / min. as a result natural tachycardia contractions the reset of the pulse generator 22. High frequencies at the entrance of the Amplifier 26, which have been generated by noise, interference or by faster heartbeats, for example by arrhythmia, hold the lockout circuit 36 continually in: 'blocked, prevent the reset circuit 40 from I catch a unipolar pulse signal and allow it ! pulse generator 22, to continuously generate artificial lupulse, ",. Other features of the pacemaker according to the invention are based on the operation of each block of the in

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Fig. 2 illustrated preferred embodiment explained.

The power source 12 has batteries 50 and 52, each of which is typically two mercury cells connected in series tied together. The bases of these transistors are grounded via a resistor 58, ie connected to the line 16. Their ■ collectors are each connected to line 14. The transistors 5 ¹ * and 56 each have a low saturation voltage drop between their emitter and collector, so that only a small voltage drops in them between the batteries 50 and and the lines 16 and 14 or only little power is consumed. If one of the batteries is short-circuited or interrupted, the transistors 5 ^ »56 work like an OR circuit, so that the lines 14 and 16 continue to be supplied by the remaining good battery. A capacitor 59 between lines 14 and 16 keeps transients away.

The amplifier 26 receives at input 28 both the QRS group signals from line 18 as well as the signals

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which are produced by artificial electrical cardiac stimulation pulses which have been generated by the pulse generator 22. The line 28 feeds a two-stage, galvanically coupled amplifier, which consists of an npn transistor 60 as the first stage and a collector-coupled pnp transistor 62 as the second stage. The collector and emitter of the transistor are connected to the lines 14 and l6 via high-ohm resistors 64 and 66. The collector and emitter of the transistor 62 are connected via a high-ohm resistor 68 and via a high-ohm resistor 70 in series with a high-ohm resistor 72 to the lines 16 and 16, respectively The base of the transistor 60, connected to it, receives a bias voltage via a resistor 74 from the emitter of the transistor 62, which in addition to the bias voltage generation at the transistor 60 also contributes to the direct current stabilization of the amplifier. The emitter of transistor 60 is connected to the connection line between resistors 70 and 72 via a capacitor 76 and provides AC voltage feedback for the amplifier 26. The emitter of transistor 62 is circuit-grounded via a capacitor 71 and a normally closed switch 73 · The switch 73 inserts a series resistor 75 between earth and capacitor 71 in its open position «,

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The amplifier 26 is upon receipt of a signal resulting from an artificial electrical pulse strongly driven into a state of saturation and remains during a considerable period of time after the disappearance of the pulse signal at its input therein State. After coming out of this state of saturation the amplifier swings into an opposite state of saturation and remains for a considerable period Length of time in this state. It generates a pulse at its output 30 when it comes out of saturation, a total of about 130 ms after the input of the signal to the amplifier 26. This saturation characteristic xk is obtained the amplifier 26 through the AC and DC feedback in connection with a phase change generated by the capacitors 71 and 76, by which in the In a manner known to those skilled in the art, a sudden overshoot is generated.

Since the amplifier's response is limited to low frequencies, only the QRS group of the natural heart signal detected. The amplifier 26 does not go into saturation when receiving natural QRS signals, because their size is much smaller than the size of the signals from artificial stimulation impulses. Through the QRS signals

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therefore, no amplifier delay is caused.

The through a differentiating capacitor 78 from the collector of the transistor 62 coming to the output 30 of the amplifier 26 signals have both polarities. The QRS group signals can only have one polarity. The comparator must full-wave rectification of the pulses at the output perform as the reset circuit 40 can only respond to one polarity.

The output 30 is therefore connected to the base of an npn transistor 80 and to the emitter of an npn transistor 82 and also has a connection to earth via a resistor 84, the collectors of the Transistors 80 and 82 are connected to one another and feed a pnp transistor 88 via a resistor 86 and through a resistor 90 the line 14 carrying the high voltage. The emitter of the transistor 88 is connected to the Line 14 through a normally closed switch 85 in connection, while its collector with the Output 34 and a capacitor via a series circuit 92 and a resistor 94 to the base of the transistor 82 and is connected to earth via a resistor 96. A parallel connection of a capacitor 89,

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a resistor 87 and a zener diode 91 connects the switch 85 in the normally open position Emitter of transistor 88 with line 14.

When a pulse of one polarity appears at the output 30, one of the transistors 80 and 82 is switched on, thereby switching the transistor 88 on and the transistors 82 and 80 are kept switched on by feedback for a period of time which is determined by the time constant of the capacitor 92 and the resistors 94 and 96 is fixed »

Transistors 80, 82 and 88 are off except during an output pulse from the amplifier 26, and no current is consumed by the comparator to generate a bias voltage, except during an output signal from the amplifier. As a result, the power consumption of the comparator 32 is minimal held. The forward voltages of transistors 80 and form a threshold through which noise is partially filtered out.

The output 3 ^ of the comparator 32 is connected to the blocking circuit 36, which consists of a conductive connection from the output 3 ¹ J via a series diode 98 and a resistor

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stood 100 to a capacitance 102 and a resistor, the latter is connected to an npn transistor, the emitter of which is grounded for setting the refractory period. In addition, a high-resistance resistor 108 leads from the output 3 ¹ * to the collector of the transistor 106, from which the output 38 of the blocking circuit 36 branches off.

The blocking circuit 36 directs pulses from the output 3 ^ of the comparator 32 via the output 38 to the reset circuit until the transistor 106 is switched on has been. At this point in time, output 38 is grounded. As a result, the first pulse comes from the Comparator 32 to the reset circuit 40 and also charges the capacitor 102 until the transistor 106 switches on and the forwarding of further pulses from the comparator 32 to the reset circuit 40 for so long blocks until the capacitor 102 has discharged through the resistor and the transistor 106. This will make the fixed proportion of the refractory period. Every impulse from the comparator 32 in the meantime charges the capacitor, although it does not reach the reset circuit 40 102 and starts again with the clock

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control of the fixed part of the refractory period _β

In addition, the amplifier 26 then receives signals both natural QRS ventricular stimuli and artificially generated impulse stimuli. The former Signals are amplified without delay and trigger the fixed portion of the refractory period and also cause via the reset circuit 40 to reset the Pulse generator 22 when the locking circuit 36 at Appearance of the QRS signal not in a lockout state has been. If an artificial stimulus impulse is generated, an impulse signal arrives with the same result as at the QRS signal through amplifier 26, with the exception that the saturation behavior of amplifier 26 produces a train of pulses at its output, which essentially after passing of the artificial stimulation impulse appear and polygamy re-trigger the fixed portion of the simulated refractory period, to bring about a longer total duration of the locking state.

A change in the characteristics of the simulated refractory period is made by switching the switches 73 and reached into the normally open switch position, in which the resistor 75 between earth and condenser

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Sator 71 and the parallel connection from resistor 87, the capacitor 89 and the zener diode 91 are connected between the line 14 and the emitter of the transistor 88 is. Adding resistor 75 su to the circuit of the amplifier 26 changes the phase adjustment and the attenuation of the closed loop amplifier, so that a sudden pulse overshoot is prevented, which saturation with signals from artificially excited Causing heartbeats. The capacitor 89 charges each time the capacitor 102 is charged, and discharges through resistor 87 at a slower rate than capacitor 102, through each pulse from the amplifier 26, the capacitor 102 is charged to a variable voltage level, which in reverse Relative to the charge remaining in the capacitor 89. When faster signals appear on At the input of amplifier 26, the capacitor discharges from amplifier 26 between pulses at comparator 32 less, resulting in less charge and voltage on capacitor 102. The lockout period that generated by the interlock circuit 36 is at more frequent received heart signals also shorter.

The simulated refractory period changes with it

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the frequency at which the amplifier 26 receives signals either due to natural heartbeats or due to artificially stimulated heartbeats. This allows a relatively long simulated refractory period for normal heart rates, which induced either naturally or artificially x "/ orden, and also permits a simulated short refractory period in tachycardia I _s erzschlägen! A continual blocking state to prevent. Zener diode 91 limits the charge on capacitor 89 so that there is a simulated minimum refractory time and so that higher frequency signals or noise signals received by the amplifier create a persistent blocking condition and generation of artificial pulses as before.

Of course, the switches 73 and 85 can also be omitted in any cardiac pacemaker according to the invention, and a cardiac pacemaker can be constructed in such a way that it works with or without resistors 75 and 87, capacitor 89 and Zener diode 91 with a respectively desired simulated refractory time.

It is also clear that the capacitor 89 is in place

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with the line; 14 also be connected to line 16 can or that all three components of the parallel connection instead of between the capacitor 102 and the line 14 at any point in the charging branch of the capacitor 102 can be inserted.

A reed relay 110 forms a normally open switching contact between output 38 and ground. It can be actuated by an external magnet in such a way that it closes the switching contact and thereby the output and temporarily also grounds the input of the reset circuit.

The reset circuit 40 consists of an npn transistor 112, the base of which is connected to the output 38. The emitter and collector of the transistor 112 are each connected to the collector and the base of a pnp transistor 114 connected, whose collector is grounded and whose emitter is connected to its base via a resistor ILo. V / enn consequently the input of the reset circuit 4o is earthed or there is no pulse signal at this input, both transistors 112 and 114 are turned off and have no influence on a voltage at the emitter of the translator 114. If through the blank circuit 36 a pulse

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Through the grain, both transistors 112 and 114 are turned on and the emitter of transistor 114 is thereby grounded.

The transistors 112 and 114 are, except when resetting the pulse generator, off and therefore contribute to a low current consumption of the circuit.

The emitter of transistor 114 is connected to the ungrounded side of a grounded clock control capacitor 118 of low capacitance. The same side of the capacitor 118 is connected to the line 14 via a high-resistance variable resistor 120 and a high-resistance plague resistor 122. A combination of the resistors 120 and 122 and the capacitor 118 forms a, low power receiving RC-charging circuit, v / elk by the reset circuit ¹ IO always can vjerden) discharged quickly if at the input of a pulse for grounding the emitter of the Transistor 114 is present.

The connection line between the capacitor 118 and the resistor Ii22 is connected to the emitter of a pnp transistor 124 connected. The base or the collector of the

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Transistor 124 is on the collector or base an npn transistor 126, the emitter of which is grounded. A voltage reference circuit with low current draw is through a high resistance 128 between line 14 and the collector of transistor 126 and When the Voltage on capacitor 118 is increased until it equals the voltage on the collector of the transistor plus the forward voltage of the emitter-base diode of transistor 124, capacitor 118 is across the Transistors 126 and 124 and a collector resistor quickly and completely discharged towards the earth. During this discharge interval is the collector of the transistor grounded so that a negative pulse is generated at the collector of this transistor during discharge. This Pulse becomes base from the collector of transistor 126 through capacitor 134 and resistor 136 a pnp transistor 138, the emitter of which is connected to the line 14. A bias resistor connects the line 14 with the connecting line between the capacitor 134 and the resistor 136. The collector of transistor 138 is via a feedback circuit,

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which is a parallel connection of a capacitor 142

with a series connection of a resistor 144 and

a diode 146 connected to the base of the transistor.

The resistors 120 and 122 and the capacitor together with a discharge path for the capacitor 118 via the transistors 124 and 126 form a periodic pulse generator, the period of which is determined by the charging time of the capacitor 118 via the resistors 122 and 122. _O pulses can be kept indefinitely esperrt by the capacitor 118 is discharged through the reset circuit 40 and is kept in a discharged state. On the other hand, the pulse generator operates continually, and a i ^r olge generated by pulses, such as when the reed relay and the base of the 'transistor 112 is enabled 110 grounds, at a constant voltage source 12, the period between the pulses constant at about 0 , 8 s set. However, as the voltage of source 12 decreases, the lateral span between individual pulses will increase to a known extent because the forward voltage of the emitter-base diode of transistor 124 is a characteristic component of the voltage of source 12. This increases the percentage

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satε the supply voltage »which at the capacitor must be applied to make transistor 124 conduct "This inherent dependence of the pulse frequency on the voltage allows accurate and easy monitoring the pulse frequency at low voltage by just adding the relay 110.

The duration of the pulse generated at the collector of transistor 138 and to the base of the transistor 126 arrives, the clock control circuit 134, 13b and l40 and the feedback branch from the collector of transistor 138 to the base of transistor 126, i. by a circuit which already forms part of the pulse generator, adjusted to about 1 ms. This particular feedback arrangement enhances and contributes to the on-state of transistors 124 and 126 at, the width of the pulse at the collector of the transistor against changing loads on the collector of the To keep transistor I38 essentially constant. The pulse pause is regulated by disconnecting the clock control capacitor II8 from the output. the Pulse duration decreases with the source voltage. This is an indicator that also shows the state of the Indicates energy source and this from other possible heart

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distinguishes between step-by-step errors.

The collector of transistor 138 connects a push-pull voltage doubling circuit via a voltage divider, which is formed from resistors 148 and 150, to ground. The connection line between these resistors is connected to the base of a grounded emitter transistor 152, the collector of which is connected to one side of a voltage doubling capacitor 15 ^. the other side of this voltage doubling capacitor 15 ^ is connected to the pulse line 18. The collector of the transistor 152 is also connected to the input 23 of the amplifier 26 via a series circuit of a capacitor 156 and a resistor I58, whereby a connection between the line l8 and the input of the amplifier 26 is established. Finally, the collector of the transistor is connected via resistors I60 and 162 to a high voltage line 164, which is decoupled from the line Ik by a series resistor 166 and a parallel capacitor I68 for protection against short circuits. The connection between the resistors I60 and 162 is connected via a capacitor 170 to the base of a pnp transistor 172, the emitter of which is connected to the line and the collector of which is connected to the pulse output line 20

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and whose base is connected to the line via a resistor 1? 4. The pulse lines 18 and 20 are each connected to earth via resistors 1J6 and I78 and via a Zener diode ISO, which prevents too high a voltage drop across them «

During the period when no pulses are being generated or received, the capacitor charges to full voltage on lines 164 and 16. During the pulse pause, when the capacitor II8 is discharged, the transistors 152 and 172 then switch this capacitor 154 in series with the voltage between the lines 164 and 16 on the pulse lines 1 <3 and 20, so that a pulse is generated on the latter, whose voltage is twice as great as the voltage of the source 12,

In addition to the current which is required for generating a cardiac stimulation pulse, the pulse generator of the reference resistors 128 and 130 and the Ladungsv ^»T iderstände requires 22 because of the large impedances 120 and 122 together with the capacitor Ho and because of the on-off state of the transistors 124, 126, 133 »152 and 172 only have a very small lifting current, except during a pulse when the transistors are saturated and a small one

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Consume power.

It has thus been shown how the voltage doubling of the pulse generator output leads to an increase contributes to the service life and reliability of the battery and to a self-indication of the battery condition. the Voltage doubling allows a lower supply voltage and consequently less power consumption. Fewer batteries are required or can be redundant batteries can be provided. The lower supply voltage also increases the dependency the pulse pause from the supply voltage and enables it in that an electrocardiograph can monitor the battery status on the basis of the battery voltage. The reed relay 110 can be activated by an external magnet to enable this measurement. Since the Voltage doubling without a transformer, v / elcher represents an unreliable component in itself, is achieved, the expected service life is extended.

FIG. 3 shows another embodiment of the in? Ig. 1 shown pulse generator. The pulse generator in Fig. 3 differs from the pulse generator 22 in Fig. 2 on the capacitor 13 ¹ I addition, where this

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is connected to a resistor 182, which is on the other hand connected to the line I ^ ₀ The capacitor 13 ^ iat also connected to the collector of an NPN transistor 104 provided with a grounded emitter and to a connection terminal of a voltage doubling capacitor, the other terminal of which is connected to the pulse line 18. Since: - 'ELn ^ an ^ .arijjnal am Einplane of the amplifier 2υ is besides.lern von de .; "Taken capacitor 134 across capacitor 156, capacitor 188 connects the capacitor ..ia lji'l-" bor ^a üii =; il / ideratand 190 with the EASIA a pu ^ ^ -Tran istor :; L ^ d ₃ whose emitter the line K ^ l. I ¹ ^ r collector dea i'ransiütors 192 is connected to the IiapuLi: teitutiö 20 and via a!. '!! erstand 194 with' earth, a contradiction l ') 6 connects the arulere Aua ^ an ^ nLupuluLleuus lc! nit earth. A '.'...' ioohen d \ .o Lei do / en l °> and Λ "./'-ociialtebe! isner ~ d'ode Ij i serves ils überfipannunjsüohut .:. Dor collector of transistor iy2 is tußerdem with the Rückkopplun is formed, else without the capacitor V \ 2;;.;! Süühalturitj, plural marriage from the V / esistance l ^l \ '\ and the diode 1 ^ 6 prior to,,.. , and furthermore connected to the base of the transistor 184 via a resistor 200.

The operation of the in Fic. 3 is the circuit shown

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Although identical to the operation of the circuit shown in FIG. 2, the same function is achieved more reliably and with less weight and lower power consumption, since a transistor v. ^r ess present. During the standby state, when no lupulses are generated or received, the capacitor 186 charges to the full voltage of the source 12. During a pulse, the transistors 184 and IQ2 then switch this capacitor 106 in series with the voltage of the terminal 12 at the output terminals 18 and 20 and there generate a voltage pulse which is twice as large as the voltage of the source 12 »

In Flg. 4 is shown a further modified embodiment the generator of the pulse shown in Fig. 2 "The charging and discharging ^ Itir the capacitor 118 are basically the gleijhoii as in FLg ₁ 1 nit except there."I'.ollektcr of the transistor 126 is connected to the base of transistor 124 through a parallel circuit of a low forward voltage diode 202 and a capacitor 204, the diode 202 being arranged to conduct from the base to the collector, a resistor 206 connecting the lead Ik with the collector de3 transistor 126 and a pulse conducting

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Capacitor 2Ou comes from the collector of the transistor via a resistor 210 to the base of a pnp transistor 212, the emitter of which is connected to line 14 and whose collector is connected to ground via a resistor 214. The pulse line 20 is connected to the collector of the transistor 212 and the pulse line 13 is connected to the collector of the transistor via a voltage doubling capacitor 21b. The feedback circuit comprising components 144 and 146 is connected between the collector of the transistor and the base of transistor 126. A capacitor 218 can be provided to connect the collector of transistor 126 to the input of amplifier Ζύ. A resistor 220 connects the line 1 ^J I with the connection line between the two. V. 'resistor 210 and the capacitor 208.

During the state of readiness and during which no impulse is generated or received, the Capacitor 21G to the full voltage between the Lines 14 and 16 about the load between the Terminals Io and 20. '..' then the capacitor 118 is discharged during the impulse state, switch the Transistors 126 and 212 connect the capacitor 216 to the Voltage of source 12 at load 24 in series «The

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209819/0580

Diode 202 prevents the resistor 206 from the very affects the high impedance of the reference resistors 128 and 130 during the standby state. The diode can be replaced by a field effect transistor or by any component that has a low resistance and is only conductive during the discharge of the capacitor 118.

The circuit shown in figo 4 generates with a minimum of components resettable pulses with extremely low current consumption. The circuit itself can as a generator for the continuous generation of a sequence

use of pulses or as a continuously operating a cardiac pacemaker, wherein the ability to provide stimulus signals only when needed, not of this circuit must have _o In order to achieve with a minimum of components, a part of the control ability of the pulse width and the pulse interval must v sacrificed when the load fluctuates /earth"

Based on the description of a preferred embodiment of the pacemaker according to the invention is shown like a heart patient through a simple lightweight pacemaker with long life im

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215QU4

planted state, with high i'.uver U'.sj L ^ speed, with its own data status but ^ achun ^, mib controlled Aussan ^ üimpuls, with automatic Knderuru ;; the simulated ROiTraktilrzeit and with continuous cardiac stimulation can be helped in the presence of exit signals.

Within the scope of the invention, rrioh offers the person skilled in the art beyond the described execution at;.; piele beyond of course a variety of simplistic and Possibilities for improvement both in terms of Structure al'3 also the mode of operation de :; e

209819/0580

Claims (20)

2150U4 claims; 1.) Herzsohrictmactuir ·, characterized by a resettable pulse generator (22), following its provision generates an artificial cardiac stimulating pulse after a certain interval, and also by a detector circuit {26, 32) performing the detection of an artificial or natural cardiac stimulating pulses signal, Welter by a reset circuit (40) which, as a function of a determined natural cardiac stimulus line, resets the pulse generator, which resets itself when an artificial cardiac stimulus pulse is generated, furthermore by a locking circuit (^ 6), which the reset circuit during a period of time after the detection of each natural or artificial heart rate signal from resetting the pulse generator, and finally by a portable electrical power source (12), the output voltage of which is lower than the voltage required for artificial heart stimulation. 2. Heart pacemaker according to claim 1, characterized in that the pulse generator (22) has a one low power consumption, non-inductive push-pull -.-58 αϊ-; 8 0 2150H4 Has voltage doubling output circuit (46), which the artificial heart stimulus pulse of the pulse generator about twice as large as the maximum output voltage the energy source (12) makes. 3 · Cardiac pacemaker according to claim 1 or 2, characterized in that the pulse generator (22) is so designed is that he has the certain pause and the width of the pulse despite the change in the load (24) on the pulse generator in the essential constant. 4. Heart pacemaker according to one of claims 1 to 3, characterized by a circuit structure in which the majority of the active components are normally switched off and therefore only one has low power consumption. 5. Heart pacemaker according to one of claims 1 to 4, characterized in that the detector circuit (26, 32) starting with the determination of each cardiac stimulus signal, a large number of output pulses are generated and thus during a delay period continues, which increases with the level of the detected cardiac stimulus signal, - 39 - 209819/0580 Ho whereby natural cardiac stimulus signals have a negligible delay time span, whereas artificial cardiac stimulus signals cause a considerable delay period, and that the locking circuit (36) is designed so that it generates a fixed blocking period after the last output pulse from the detector circuit (26, 32). 6. pacemaker according to claim 5 * thereby characterized in that the detector circuit (26> 32) has a * Amplifier (26) with a large amplification factor and with a saturation characteristic which consists of artificial cardiac stimulus signals, alternating saturation states of the amplifier are generated, these saturation states, which persist during the delay period with each transition of the amplifier into a Saturation state and from this generate an output pulse at the detector circuit. 7. Cardiac pacemaker according to claim 6, characterized in that the detector circuit (26, 32) has a Comparator circuit (32) for generating a unipolar signal, which the deviation of the output signal of the amplifier (26) from a noise threshold in the vicinity of an idle state at the amplifier output (30) indicating the output signal of the comparator circuit • ho ~ ? 1; : Η ι ft / π - it (I. causes the restart of the blocking period of the blocking circuit 06), 8. A pacemaker according to claim J, characterized in that the blocking circuit 06) has a capacitor (102), a charging circuit (89, 98, 100) for charging this capacitor to the level of the unipolar signal in each case when it appears and a discharge circuit (104, IO6 , 107), which discharges this capacitor during an interval defining the blocking time, the reset circuit (40) always being blocked when the charge on the capacitor (102) is above a certain value. 9 · Cardiac pacemaker according to one of Claims to 9 *, characterized in that the blocking time period generated by the blocking mechanism 06) can be changed i'i'p, 75; 85, 37, 89, 91) and decreases with decreasing frequencies of the detected signals so that a longer simulated refractory period is produced at normal heartbeat rates and a shorter simulated refractory period at tachycardia heartbeat rates. 10. Cardiac pacemaker according to claim 9, characterized - 41 209819/0580 ie characterized in that the 3 lock circuit (36) an RC clock control circuit (102, 104), the change in charge from a stable state of charge can be adjusted when a cardiac stimulus is set, the gradual return to the stable state of charge defines the variable lock period, and a further RC Clock control circuit (87, 89) with a greater time constant than that of an RC circuit, the charge of the further RC clock control circuit changing from a stable state of charge when a cardiac stimulation pulse is set, and the change in charge of the one RC circuit at every detected signal decreases with the difference in charge of the further RC circuit from its stable state of charge. 11. Heart pacemaker according to one of claims to 10, characterized in that the output voltage the energy source (12) decreases when it is exhausted, that further the pulse generator (22) has a capacitor (118) and a charging path (42) assigned to it between the terminals (14, 16) of the energy source, and that a discharge path (4 ^) for discharge this capacitor over at least one transition - 42 - 209819 / OK80 21SOH4 13 zone of an active semiconductor element (124) is provided, the forward voltage of this transition in the Relation to a reference voltage defines a point of capacitor charging at which a discharge cycle begins and at which an electrical cardiac stimulus is generated, and with a decrease the output voltage of the energy source to an increase in the pause between the electrical cardiac stimulation pulses leads. 12. Cardiac pacemaker according to one of claims 1 to 11, characterized by circuit means (110), which respond to an external magnetic field and cause continuous artificial impulses for determination the degree of exhaustion of the energy source. 13. Cardiac pacemaker according to one of claims 1 to 12, characterized in that the energy source (12) has redundant batteries (50 _f 52 ) connected in parallel and that a circuit element (54, 56) conductive only in one direction is connected between each battery and a connection terminal (14) of the energy source. 14. Cardiac pacemaker according to one of claims 1 * characterized to 13, that the pulse generator (22) C ö ß 1 ίί Π ^{ λ 8 Π 21501U fr a freely oscillating astable multivibrator (4j5), which works with the preselected period of the artificial cardiac stimulation pulses, and a monostable multivibrator (44) which, when the state of the astable multivibrator changes, generates a pulse generated with the determined pulse width and which a feedback branch containing the astable multivibrator which keeps the pulse width constant regardless of changes in load, and which * also keeps the period of the astable multivibrator independent of the load. 15. Cardiac pacemaker according to one of claims 1 to 14, characterized by a capacitor (118) with an associated charging circuit (42) which supplies it with energy from the energy source (12) by the presence of a reference voltage signal at the connection terminals (14, 16) of the energy source, further k through a switching loop (43) to discharge the capacitor (118) whenever the signal is on this Capacitor has reached a certain ratio to the reference voltage signal, the switching loop has a pulse terminal connected to a terminal of the power source during the discharge of the capacitor (118) - 44 2150H4 Η? is connected, further by a further capacitor (154), which between the pulse terminal and a The terminal of the load (24) is connected, furthermore by a charging circuit for the further capacitor, which charges this during the charging of one capacitor to the potential of the energy source, the Pulse terminal is at the potential of a further connection terminal of the energy source, and finally through a circuit for connecting the further connection terminal of the energy source during the discharge of one capacitor with another clamp of the load. 16. Heart pacemaker according to claim 15, characterized in that the switching loop (43) is a component with controlled conductivity, to which a capacitor is connected in parallel and which only During the discharge of a capacitor (II8) conducts, also a transistor of a certain Conductivity type and a further transistor of the opposite conductivity type, wherein Emitter, base and collector of one transistor each with a connection terminal of one capacitor (II8) and also connected to the conductivity controlled device, thereby a line from the emitter - 45 209819/0580 2150K4 of one transistor takes place through this component to the base of the further transistor, and wherein the emitter and collector of the further transistor are each connected to the one connection terminal of the energy source (12) are connected and a connection to a further connection terminal of the capacitor and to the other connection terminal of the component with controlled conductivity as well as a connection to the pulse terminal, and finally wherein the charging path for the further capacitor (154) has impedances which are between the another terminal of the energy source and the pulse terminal and between the one terminal of the Energy source and the other terminal of the load (24) are connected. 17 · cardiac pacemaker according to one of claims 1 to 16, which works as an emergency cardiac pacemaker, characterized by a device (26, 32) for generating an adjustable refractory period which is a Has a circuit for generating a plurality of signals each time a cardiac stimulus signal is set, said plurality of signals being present for a period corresponding to the level of the detected Cardiac stimulus signals become larger and this period of time - 46 - 209819/0580 2150H4 for artificial signals longer and for natural signals is significantly shorter, and that the device for generating the refractory period has circuit elements which trigger a specified period of time during which, when each signal of the plurality of signals occurs, the Reset is blocked. 18 «pacemaker according to claim 17, characterized characterized in that the circuit (26, 32) for generating a plurality of signals, the amplifier (26), which is longer when artificial stimulus signals are detected Time is saturated and not saturated when natural stimulus signals are detected, and that the circuit elements have an RC clock control circuit for triggering the specified period of time, which at each Change at the output (30) of the amplifier is excited and leaves a stable state of charge on which it then gradually returns, with the state of charge gradually returning on the stable state of charge inhibits resetting, while the stable state of charge prevents resetting does not lock. 19. Cardiac pacemaker according to claim I7, characterized 21501U characterized in that the detector circuit (26, 32) resets the pulse generator (22) during a Pause blocks, which changes inversely with the frequency of occurrence of the detected cardiac stimulus signals, this pause being longer for normal heartbeat rates and shorter for tachycardia heartbeat rates so that during a tachycardia condition a Artificial irritation is prevented. 20. A pacemaker according to claim 19, characterized in that the pulse generator (22) can be reset with each artificial stimulus pulse which appears after a certain pause after resetting the pulse generator and, if it is not reset, pulses at the certain frequency generated, wherein the specific pause corresponds to the pulse period which is determined by the specific frequency, and that the detector device (26, 32) senses natural and) artificially generated cardiac stimulus signals and resets the pulse generator when such stimulus signals occur, the detector circuit resetting the pulse generator locks during a changeable, simulated refractory period following the last sensed signal. - 48 - 209819/0580 Empty first