DE3110013A1 - Rate-related tachycardia control pacemaker - Google Patents

Abstract

There is provided an improved pacemaker for the control of tachycardia. After confirmation of the occurrence of tachycardia a burst of at least three stimulating pulses is generated. The time intervals between successive pulses decrease by a fixed decrement, and thus the pulse rate during each working cycle increases and the burst can be characterised more accurately as "tweet". The first pulse is generated after the last heart beat used for confirmation of the occurrence of tachycardia, specifically at a point in time which depends on the rate of heart beats in the tachycardia. The time delay between the last heart beat and the first pulse in the tweet is equal to the time interval between the last two heart beats minus the constant decrement which characterised the successive time intervals between the stimulating pulses. Since successive pulses are generated at an increasing rate and since the first pulse is generated at a point in time which depends on the tachycardia it is more likely that the tachycardia will be terminated.

Description

The invention relates to tachycardia control pacemakers, in particular to us

special such pacemakers that generate stimulating impulses.

Tachycardia is a condition in which the heart beats very quickly, typically more than 150 beats per minute. For ending the tachycardia Several different pacemaker modalities have been proposed. That underlying principle of all of these is that when a pacemaker stimulates the heart at least once shortly after a heartbeat, before the Next naturally the heartbeat will occur at a very rapid rate to the heart if appropriate successfully returns to sinus rhythm. The tachycardia is often the result of electrical feedback inside the heart, and a natural one Heartbeat leads to the feedback of an electrical stimulation which is premature triggering another heartbeat. By interposing a stimulated heartbeat the stability of the feedback loop is destroyed. As with conventional pacemakers the electrodes of the tachycardia pacemaker can be atrial or ventricular be coupled. Albeit the detection of atrial heartbeats and atrial pacing are preferred, ventricular sensing and pacing may also be used will.

In the patent application of the same applicant and the same filing date with the designation Tachycardia control pacemaker working with two pulses " such a pacemaker is described that produces a single pulse or two Generates pacing after each confirmation of the presence of tachycardia.

The delay between the last heartbeat, which is necessary for confirming tachycardia is applied and the first stimulus is considered the initial one Delay and the interval between the first stimulation and the second stimulus (when a second stimulus is generated) is called the "coupled." Interval ". With this pacemaker, the doctor can set maximum values program for the initial delay and the linked interval. Of the Pacemaker automatically senses both the initial delay and that coupled interval during successive cycles, and at Both scan sequences have 15 decrements with 6 milliseconds. The overall result is that up to 256 different, timed stimulation pairs can be generated to terminate a tachycardia.

The difficulty with tachycardia control is that Usually there is no way of knowing exactly when a stimulus is given should be applied. One or more impulses should be shortly after a heartbeat and before the kick point at which the next premature blow is hit otherwise it would occur, but usually there is no way to be precise know when the impulses should be generated.

As an alternative to this type of scheme is suggested been a single pulse after the last heartbeat in confirming the Presence of tachycardia, which is related to the heartbeat rate stands. By relating the single impulse generated to the actual one Rate at which the heart beats, it is more likely that the only one generated Pulse ends the tachycardia. Nevertheless, it was found that such only one-pulse method is not maximally effective.

It is an object of the invention to achieve a more effective one Create pulse pacing rate for ending a tachycardia, and indeed a sequence related to the rate of heartbeat in tachycardia.

According to the invention, a burst of at least three pulses is followed generated after each confirmation of the presence of tachycardia. The time intervals between the pulses decrease and thus the pulse rate increases continuously, and the overall sequence will be more accurate than a chirp De, since its RAte is continuous increases. The successive time intervals between the pulses increase the same immutable decrement. This kind of increase in the pulse rate during a single duty cycle was found to be effective for balancing the tachycardia and the acceleration of the pacemaker over a short interval leads to pacing during different phases of a tachycardia cycle and thus a greater likelihood of generating one Impeulses at the right time. Of paramount importance is the fact that that initial time interval between the last one for confirming the tachycardia applied heartbeat and the first pulse of the sequence in relation to the rate of heartbeats and equal to the heartbeat rate minus the unchanging one Is decrement.

For example, suppose that during a particular tachycardia that Heart beats at intervals of 300 milliseconds. When the immutable decrement amounts to 10 milliseconds, the first pulse generated will be 290 milliseconds occur after the last heartbeat of the tachycardia. The next to be generated Pulse is generated 280 milliseconds later, etc. It becomes a predetermined one Number of pulses generated. However, the number of pulses generated should be unchangeable Decrement and the initial heart rate be such that the time intervals otherwise between successive pulses towards the end of the sequence fall below a minimum "safe" level (this could lead to fibrillation lead) the last pulses of the sequence are at a steady rate above of the smallest safe value. Thus, in the case of the invention explained here Embodiment the same number of pulses always during each working cycle generated although the pulses at the end of the cycle with an invariable maximum Rate can be generated should the successive decrement of the time intervals between the pulses result in pulses being generated at too fast a rate (a typical smallest interpulse interval is 200 milliseconds, a fixed decrement of 5 or 10 milliseconds is preferred and so is it will generate a predetermined number of pulses in the range of 10 to 20 considered. Alternatively, instead of generating a specified Number of pulses the pulses can be designed so that they stop after they have been generated over a predetermined period of time).

An embodiment of the invention is shown in the drawings tnd is described in more detail below. They show: FIGS. 1 and 2 when they are arranged side by side an embodiment of the invention; The pacemaker has a pair of electrodes on, the indifferent electrode by the reference numeral 16 and the stimulating Electrode is represented by reference numeral 14.

The output stage 18 is a conventional heart pulsator, the one Pulse is applied to the stimulating electrode when a trigger pulse occurs at the entrance. The input stage 20 and the comparator 22 are also conventional pacemaker circuits and the same are used to stimulate heartbeats determine, with each heartbeat causing the output of the comparator 22 is pulsed high.

The timing equipment consists of a counter / timer 30 that counts through the timer 36 is controlled. As explained below, each identified performs Heartbeat to reset the counter / timer. Within 100 milliseconds Refractory period after each heartbeat is each determined by the input stage 20 Signal is ignored and this is the traditional pacemaker operation that prevents multiple determinations of the same heartbeat. The flip-flop 10 the gate 12 sets a period of 100 milliseconds after each detection of one Heartbeat inoperative.

The same pulse at the output of gate 64 that the counter / timer 30 resets, also resets the flip-flop 10, as explained below. Thus, every detected heartbeat leads to a reset of the flip-flop, the Q output going low, rendering the gate inoperative 12. Now that the payer / timer is reset, it starts after count above. # After 100 milliseconds have elapsed, the QN output of the counter / timer goes to a high potential. The flip-flop 10 is now clocked and there on its If a high potential is applied to the D input, the Q output goes to a high level Potential and the gate 12 is again put into operation.

As soon as the output of the gate 60 for the first time at a high potential goes when every heartbeat is detected, as explained below, the exit goes of the pulse shaper 38 momentarily to a low potential after a short delay. However, if the output of gate 60 initially goes high, then stands the output of the pulse shaper 38 under a high potential, and the input of the Gate 42 is switched to the working position. The QN output of the tachycardia detecting Counter 46 is normally at a low potential, and the same is applied to one of the inverting inputs of the gate 42, so that a the second input of the gate is normally switched to the working position. The impulses at the output of the gate 12 are on a third, non-inverting input of the gate 42 hits. Thus, every detected heartbeat leads to that the output of gate 42 goes high provided that the inverting input of gate 42, # connected to the output of gate 34 is, is at a low potential at this time.

However, when the heart beats in a sinus rhythm, the exit goes of the gate 34 to a high potential and the heartbeats do not cause the Output of the gate 42 is pulsed up.

There are two inputs of the comparator 42. The B input signals are through the tachycardia window tab. 92 formed. This register with three state outputs is normally indicated by the low potential at the QN output of the tachycardia fixed-disk counter 46 switched to the working position. tThe three status outputs of the adder 76 have no effect on the B input signals of the comparator 42- at this point, since the adder outputs by the low potential at the QN output of counter 46 are disabled). The register 92 contains a count that is the smallest time interval between normal heartbeats, typically 350 milliseconds. Only when heartbeats with larger Speed, they are considered part of a tachycardia (provided that the smallest number of such pulses is consecutive is detected). The output signals of the tachycardia window are applied to the B-Einsånge of the comparator 32 is applied. The other inputs, the A inputs are controlled by the outputs of the counter / timer 30. Under the premise that the heart is beating in a sinus rhythm becomes the counter / timer 30 have counted to a value greater than that indicated by register 92 again ^ is given when a heartbeat is detected. Although Gate 12 operates to indicate the detection of a heartbeat thus one of the A = B or A> B (usually the latter case) outputs of the comparator 32 will be at a high potential and the output of gate 34 will be at a high Be potential, disabling gate 42. As long as the heart is normal strikes, the output of gate 42 will thus not emit pulses. Every heartbeat simply resets the counter / timer and flip-flop 10. Since the QN output of counter 46 is below a low potential below Switching the gate 60 into the working position, every pulse is at the output of the gate 12 passed through the gate 60, the delay element 62 and the OR gate 64 below Resetting the flip-flop and the counter / timer.

However, the heart should be beating at a rate that is sufficiently rapid to be assessed as part of a tachycardia becomes dependent from the value stored in register 92, when # n gate 12 is operating, the counter / timer have not counted up to the value that is present in register 92.

Thus the B inputs of the comparator will be a larger bet than which have A inputs and both comparator outputs are below a low Stand potential. After the output of gate 34 is at a low potential is located, the corresponding input of the gate 42 is brought into work function and the gate exit is at a high potential when a heartbeat is detected will. After a short delay introduced by the delay element 44 the count in counter 46 is incremented. This is the counter that is used for the Detecting a predetermined number of consecutive heartbeats applied all entering at a greater rate than they would through the tachycardia window register 92 is reproduced. Typically there must be at least five such consecutive fast heartbeats are detected before tachycardia is confirmed and at this point the QN output of counter 46 goes high under regulating the pulse generation cycle.

The reason for providing the delay element 44 is to that when the QN output of counter 46 goes high, the gate 60 is disabled and its output goes to a low potential. Thus, the pulse at the output of gate 60 would result from the pulse at the output of the gate, end as soon as the Q output of the counter 4G is high Potential goes. So that the impulse does not end prematurely, since the same other functions has to perform, the delay element 44 is provided, whereby the gate 60 is attached is prevented from being disabled until the pulse at the output of the Gate 12 has ended. It should be noted that whenever the exit of the gate 60 when a heartbeat is detected, the output goes to a high potential value of the pulse shaper 38 momentarily goes low. During normal heartbeats are detected, the A inputs of the comparator 32 are below a higher value Value as the B inputs when the output of gate 12 is at a high potential value goes; since the output of the gate 37 is thus under a high potential value, operates the gate 42 does not. However, the positive pulse at the output of gate 60 leads to resetting the counter / timer 30, at which point they drop A = B and A> B outputs of the comparator both off. Resetting the counter / timer can thus cause the pulse at the exit of gate 12 to pass through the gate 42 is transmitted even for a heartbeat with sinus rhythm. To prevent this, the pulse shaper 38 generates a short negative pulse after the output of the Tors 60 initially goes to a high potential. At the time when the outputs of the counter / timer 30 has a value of 0 due to being reset by the Play gate 64, the output of the pulse shaper 38 is at a low Potential so that the gate 42 cannot work. At the time the Output of the pulse shaper 38 again to a high potential goes, the output of gate 12 is at a low potential. In order to the gate 42 is working on detection of fast heartbeats, the output of the Pulse shaper 38 does not immediately go low when the output of the Tors 60 goes to a high potential.

There is a slight delay so that the pulse at the Output of gate 12 can be transmitted through gate 42, the output should of gate 34 are at a low potential when a heartbeat is detected will. Thus, the output of the pulse shaper 38 only goes low after the pulse at the output of gate 12, the outputs of gates 60 and 42 are regulated Has. The output signal of the pulse shaper prevents incorrect operation, which may otherwise arise due to the resetting of the counter / timer 30th

It is necessary to store the count value in the counter / timer 40, which reproduces the last intermediate beat interval, since this count value reflects the rate, with which the kicks kick, and the heart rate is used for regulating the initial rate at which the stimulating pulses are generated. Any positive pulse appearing at the output of gate 60 is through the gate 74 and sets the input R-R lock 72. in work function. This lock is used for storing the count value in the counter / timer 30. (The Terminology R-R lock is used here to indicate the fact that what is stored is a count representing the time interval between successive R-waves, although when the stimulating electrode is connected to your Atrium of the patient is actually the interval between P waves, that is saved). The same pulse at the output of gate 60 is applied to the Sh "Select the Ar input of the multiplexer 70. If this input is under a If the pulse is high, the multiplexer transfers its set of input signals Output signals that are fed to the inputs of the R-R lock. Thus becomes the last count in the counter / timer 30 is passed through the multiplexer and stored in the R-R lock.

Each pulse at the output of gate 12 will follow the remainder of a heartbeat through gate 60 prior to confirming the presence of one Tachycardia led to thus the output of the gate 60 to a high potential to lead. After a delay introduced by the delay element 62, the pulse passed through OR gate 64 resetting the counter / timer 30 and flip-flop 10. This reset takes place as long as normal heartbeats are detected and while the counter 46 is counting the number of quick beats that the Confirm the presence of tachycardia. The last heartbeat in this cycle of confirmation for the tachycardia results in the gate 60 being disabled when the QN output of counter 46 goes high. That last heartbeat however, causes the output of gate 60 to go high and that The counter / timer 30 is reset in the usual manner. The count in the counter / timer 30 must be passed through the multiplexer 70 and in the lock 72 before the counter / timer is reset. That's the Reason for providing the delay element 62, and the counter / timer is not deferred until sufficient time has elapsed to enable it store the count in the lock 72.

It should be noted that whenever the time gate 12 is working, namely as long as the gate 60 is held by the counter 46 in the work function the count in the counter / timer 30 is stored in the lock 72, since the output of gate 60 is at a high potential value during the detection normal heartbeat and during the detection of heartbeats, corresponding to a tachycardia up to the predetermined number of such Heartbeats detected and the gate 60 is disabled. The consecutive However, storing the counts in the lock 72 does not affect the operation of the Systems. What is important is the delivery of the lock content to the adder 76, and this is regulated by operating the gate 78. Whenever the outcome of the Tors goes to a high potential value and pulses the C / A input of adder 76, becomes the count value in the lock 72 delivered to adder 76, and the contents of the decrement register 90 are added thereto in the adder. The decrement register Contains a two-complement rendition of the immutable decrement, the consecutive one Identifies time intervals that separate the stimulation pulses. Thus works the adder actually acts as a subtracter, and once this gate 78 to the first Times works, the value shown again at the outputs of the adder is the same the last count of the counter / timer 30 minus the fixed decrement. The Q output of flip-flop 84 is normally low, it is explained below, whereby an input of the gate 78 in work function is brought. As soon as the QN output of counter 46 goes high the pulse shaper generates, indicating confirmation of the presence of tachycardia 98 a short positive pulse as indicated in the drawing. This impulse is transferred through the OR gate 88 to the other input of the gate 78 under rules the first operation of adder 76.

It has been assumed that the counter 46 has five rapid heartbeats counts in sequence and each beat results in a count in the counter / timer 30, which is less than the count represented by register 92. Should however, any heartbeat after the previous heartbeat with an interbeat interval occur which is higher than that indicated by register 92, the confirmation cycle for the presence of tachycardia is canceled and the counter 46 is reset. In such a case the A> B output is available of the comparator 32 under a high potential when the heartbeat is detected is, and thus brought the input of the gate 66 into working function. Another Input of the gate 66 is connected to the output of the gate 60, which is then on high potential goes when the heartbeat is detected (until the time in which the presence of a tachycardia is confirmed and the gate through the QN exit of counter 46 is disabled), and the third input of gate 66 is in communication with the output of the pulse shaper 38, which is below a high Potential remains when the output of gate 60 goes high for the first time Potential value goes. The output of the gate 66 is thus opened a brought high potential and the pulse is reset through gate 48 of the counter 46 transmitted. The pulse at the output of gate 48 also provides the flip-flop 84 back. For this reason, the Q output of the flip-flop is below a low potential, as originally assumed above. It will be everyone normal heartbeat, even a heartbeat that occurs during a number of premature heartbeats Heartbeats has been counted (but less than the number indicating the state of a Tachycardia confirmed) resets the counter 46 and the flip-flop 84.

Once the presence of tachycardia is confirmed, the outcome remains of gate 60 at a low potential. The SA input of the multiplexer 70 remains thus at a low potential and the count value in the counter / timer 30 is no longer transmitted to the lock 72 by the multiplexer. In a similar way Thus, the counter / timer 30 can no longer by pulses at the output of the gate 60 are reset, the heartbeats play back. These impulses are through the delay element 62 and the OR gate 64 only transmit before the counter 46 confirms the presence of tachycardia #at. As soon as a tachycardia is confirmed has been, the QN output of the counter goes to a high potential before disabling desTors 60. Neither the gate 66 can regulate the resetting of the counter, since the output of gate 60 is at a low potential and is about to be disabled leads. As described below, the counter 46 is only reset after the predetermined number of pulses has been delivered.

This number is set beforehand by the doctor. The presettable one Counter 54 is provided with prefix inputs, which allow the storage of a value in the counter always regulate when the (PR) prefix input is pulsed. The pulse shaper 98 pulses the PR input when the QN output of counter 46 is on for the first time a high potential value follows the tachycardia confirmation. The one before The value set in the counter is not the number of times to be generated at each chirp Impulses, but rather the liomplemer.t of this number relative to 20.

The counter 54 increments its count whenever it does Clock entrance is pulsed up. When a maximum count of 20 is reached, the Q output goes of the counter to a high potential value and terminates the pulse sequence. If so z.I3.

15 impulses are to be generated with each chirp, would be the input inputs be tied to potentials that pre-set the counter to a counter value of 5 rules. 15 stimulating pulses are therefore required before the Q # output of the counter goes high, terminating the pulsing sequence.

The comparator 32 no longer operates to keep the count is compared in counter / timer 30 with the values stored in register 92 will. This is because the register is now inoperative because whose iN input is at a high potential, since the QN output of the counter 46 is at a high potential. The outputs of register 92 are located themselves in a three-way state, so that they have no effect on the overall operation of the system. The or # erator32 works in such a way that the count value in the counter / timer 30 at the A inputs with that stored in the adder 76 Value can be compared, the latter being applied to the B inputs of the comparator will. As stated above, the one present in adder 76 is the initial one Value of the last R-R interval minus that represented by register 90 immutable decrement.

The last heartbeat, the one that leads to the approval of one Tachycardia resets the counter / timer 30 in the normal manner. The counter then begins to count again under the control of the clock generator 36. When the count is equal to the value shown at the outputs of the adder 76 is, the A = B output of the comparator 32 goes high. this causes an input of gate 54 to go high. Of the The inverted input of the gate is normally through the QN output of the counter 54 brought into work function, which is now at a low potential value is located until the previously set number of pulses has been generated. A third The input of the gate 54 is connected to the output of the pulse shaper 38, which is at a high potential remains, since its output is pulsed low is only because the output of the gate 60 goes to a high potential value and the output of gate 60 will be at a low potential value during the pulse generation sequence held. The fourth input of gate 54 is connected to the QN output of counter 46, which is under a high potential during the pulse generation sequence. Thus, the output of the gate 54 always goes to a high potential when the Comparator 32 determines that the count in counter / timer 30 equals that Is the value represented in the adder 76.

When the output of gate 54 goes high, generated the pulse shaper 94 has a positive pulse at its output. This impulse will applied to the SB ("Select B"> input of the multiplexer 70, which thus feeds its B input signals to the outputs associated with the R-R lock 72 stand. The same impulse is passed through the gate 74 with the activation of the function the entrance of the lock. Thus, the value stored in the adder 76 becomes the Lock transferred. Shortly thereafter, the delay element 96 produces a positive Pulse at its output (the delay is provided to start the locking process to complete). This impulse controls four functions.

First, the pulse is applied to the input of the output stage 18 beats so that a stimulation pulse is generated. Second, the momentum is on applied to an input of gate 64 resetting the counter / timer 30 so that another timer cycle can begin. Third is the impulse applied to the clock input of the counter 54 while incrementing its number value. Fourth, the pulse goes through OR gate 88 and gate 78 to the C / A input of the adder 76 performed.

The previous content of the adder, which is now in the lock 72, is again stored in the adder and by the value of that in register 90 fixed decrement decreased. The adder 76 now gives the next required interpulse time interval again. The timer cycle starts again and when the A = B output of the comparator 32 to a high potential another stimulation pulse is generated.

As soon as the last pulse in the sequence has been generated, the goes QN output of counter 54 to a high potential. tiierdurch the gate 54 is out Function set so that more stimulating impulses are generated. The pulse shaper 52 now generates a short pulse which is passed through the OR gate 48 at the reset input of the counter 46 is performed. The output of the counter goes low again Potential and sets the gate 60 in work function. The system assumes that the Tachycardia has ended. If not, the counter becomes 46 Count five quick beats and there will be another cycle of pulse generation result. Dis at a time when tachycardia is again confirmed, the QN output of the counter 54 remains at a high potential and is rendered inoperative of gate 54. Only when the QR output of counter 46 goes high the pulse shaper regulates, displaying a confirmation that tachycardia is present 98 the presetting of the counter 54 and the renewed activation of the gate 54.

The flip-flop 84 is normally reset. Every operation of the Gate 48 resets the flip-flop. When the flip-flop is reset is, the Q output is at low potential so that gate 78 is in the way described above works. Only when the gate 86 is operating under clocking of the flip-flop, the Q output goes to a high potential, rendering it inoperative of gate 78, since the D input of the flin-flop is at a positive potential.

The minimum delay register 112 contains a count which is the represents maximum safe pulsation rate. In the case of ventricular pacing the register 112 contains a count value which corresponds to a minimum pulse interval of 220 milliseconds, and in the case of atrial pacing contains the same a count that has a minimum pulse interval of 180 milliseconds reproduces. The content of the adder 76 reflects the pulse interval, the regulated at any point in time during a pulse sequence will target. As long as the interval to be regulated is larger as is the smallest safe value, the A inputs of comparator 110 give one Again that is smaller than the value displayed at the B inputs, and A> B output of the comparator is at a low potential. Consequently the output of gate 86 remains at a low potential value and the flip-flop remains 84 remains deferred. However, if the time interval reproduced in the adder 76 is smaller than the minimum value, the A> B output goes to a high potential, whereby the input of the gate 86 is brought into working function. The other entrance of the gate is connected to the output of the pulse shaper 38, which is normally below has a high potential. (The pulse shaper tY is intended to correct faulty To prevent work of the different gate that arises due to the comparators 32 and 110, which otherwise operate in an indefinite manner when the counter / timer 30 is reset or the adder 76 has changed its count). As soon the output of gate 86 goes high with the flip-flop clocking 64 the Q output goes low. The system continues to work in the manner described above, however, the C / A input of adder 76 is not more pulsates when a stimulation pulse is generated. Thus the adder holds 76 returns the last interpulse time value before the output of the comparator 110 occurs a high potential goes. The last pulses in the preset number of Pulses as determined by counter S4 are generated at the same rate, i.e. with the last pulse interval, which is based on the last decrement of the count in the adder 76 resulted. (An interval that extends over the smallest safe value).

It should be noted that if the register 92 and not the adder 76 is brought into work function prior to confirming the presence of tachycardia the output signals of the register 92 applied to the P inputs of the comparator 110 will. However, this is irrelevant since register 92 has an intermediate beat interval which is used to determine the tachycardia, and this interval, that through the doctor can be hired is always greater as the smallest safe pulse interval represented by register 112 will. Thus, the A> B output of the comparator 110 is low and flip-flop 84 remains reset.

There are several different parameter values that affect pacemaker operation rules. if these are also determined during the creation of the device it may be useful to enable the doctor to determine the values to be programmed under an external regulation. To ore parameter values of this kind include those in the tachycardia window register, 92, which is previously adjustable Counter 54, the minimum delay register 112 and the decrement register 90 exist. The doctor may even want the number of consecutive program fast beats to be counted by the counter 46, to confirm the presence of tachycardia. : enn too pacemakers explained here do not allow such programming but generally working methods for the person skilled in the art for changing parameter values known under an external regulation. Reference is made here to the eincianas cited patent application relating to a detailed description of Art and way in which parameter values are set under an external control can.

Although the pacemaker is described here as being the same with fixed time interval decrements works (even if the decrement is through can be programmed by the doctor, the decrement value remains after programming immutable) it is possible; sampling the decrement values during successive ones Provide cycles using a sampling technique such as that in that mentioned above Patent application is described.

In such a case, a If tachycardia is present, a chirping pulse can be generated, with a value of the Time interval decrement is applied.

If the tachycardia is over, then this same success ) Decrement following the next tachycardia confirmation can be applied. However, if the tachycardia has not stopped, it may Decrement at the beginning of the next cycle. The decrement can can thus be scanned over a suitable range, with the decrene nominal value changes by possibly several milliseconds from cycle to cycle. The successful one Termination of the tachycardia can be determined using the same procedures as they have been described in the patent application mentioned at the beginning. :;a any heartbeat is detected following the pulse generation cycle, which follows the previous beat by a larger time interval than it does in that Register 92 is reflected, the decrement would follow the next acknowledgment the presence of tachycardia cannot be changed. Rur, rsenn a normal one Heartbeat not between the end of the pulse cycle and the next acknowledgment the presence of a tachycardia is determined, the decrement would be changed so that a new value can be tried.

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Claims (24)

Rate-related tachycardia control pacemaker Patent claims 1 Tachycardia control pacemaker, in that it does not indicate an arrangement for the acknowledgment the presence of tachycardia, an arrangement that is dependent on any operation of the confirmation arrangement responds for generating a sequence of at least three cardiac stimulation pulses, and arrangement for regulating successive cardiac stimulation pulses in this sequence to be generated after decreasing time intervals. 2. Control pacemaker according to claim 1, characterized in that g e k e n n -z e i c h n e t that an arrangement for registering the last interval between Heartbeats before the operation of the confirmation arrangement and an arrangement for that Control the first pulse in this sequence that ends at a first time interval after the last heartbeat, the smaller than the registered interval is to be generated, with successive pulses in this sequence after decreasing intervals starting with the first time interval are provided is. 3. Control pacemaker according to claim 2, characterized in that g e k e n n -z e i c h n e t that the first time interval is equal to the registered interval minus of a predetermined value, as well as successive time intervals between the pulses in the sequence differ by the predetermined amount. 4. Control pacemaker according to claim 3, characterized in that g e k e n n -z e ic That is, an arrangement for regulating the same number of times during each Pulse frequency to be generated pulses is present. 5. control pacemaker according to claim 4, characterized in that g e k e n n -z e i c h n e t that there is an arrangement to prevent pulses towards the end of any sequence are generated according to time intervals that are smaller than are a predetermined interval. 6. control pacemaker according to claim 5, characterized in that g e k e n n -z e i c h n e t that the confirmation arrangement operates to confirm a tachycardia becomes responsive to occurrences in succession a predetermined number of times of heartbeats, each of which after a previous heartbeat within occurs a predetermined period of time. 7. control pacemaker according to claim 2, characterized in that g e k e n n -z e i c h n e t that an arrangement for regulating the same number of during each Pulse frequency to be generated pulses is present. 8. control pacemaker according to claim 7, characterized in that g e k e n n -z e i c h n e t that there is an arrangement by which pulses are prevented from opposing The end of any sequence will be generated after time intervals smaller than are a predetermined interval. 9. Control pacemaker according to claim 8, characterized in that g e k e n n -z e i c h n e t that the confirmation arrangement operates to confirm a tachycardia becomes responsive to occurrences in succession a predetermined number of times of heartbeats, each of which after a previous heartbeat within occurs a predetermined period of time. 10. control pacemaker according to claim 2, characterized in that g e k e n n -z e i c h n e t that there is an arrangement to prevent pulses towards the end of any sequence are generated according to time intervals that are smaller than are a predetermined interval. 11. Control pacemaker according to claim 10, characterized in that g e k e n-n -z e I do not believe that the confirmation arrangement operates to confirm a tachycardia becomes responsive to occurrence in succession a predetermined number of times of beats, each of which after a previous beat within occurs a predetermined period of time. 12. Control pacemaker according to claim 1, characterized in that g e k e n n -z e i c h n e t that an arrangement for regulating the same number of during each Pulse frequency to be generated pulses is present. 13. Control pacemaker according to claim 12, characterized in that q e k e n n -z e I do not believe that there is an arrangement to prevent pulses from being generated towards the end of any sequence are generated according to time intervals that are smaller than are a predetermined interval. 14. Control pacemaker according to claim 13, characterized in that g e k e n n -z e I do not believe that the confirmation arrangement operates to confirm a tachycardia becomes responsive to occurrences in succession a predetermined number of times of heartbeats, each of which after a previous heartbeat within occurs a predetermined period of time. 15. Control pacemaker according to claim 1, characterized in that it is e k e n nz e i c h n e t that there is an arrangement by which pulses are prevented from opposing The end of any sequence will be generated after time intervals smaller than are a predetermined interval. 16. Control pacemaker according to claim 1, characterized in that g e k e n n -z e i c h n e t that the confirmation arrangement operates to confirm a tachycardia becomes responsive to the occurrence in succession of a predetermined Number of heartbeats, each of which was within a previous heartbeat occurs a predetermined period of time. 17. Control pacemaker according to claim 1, characterized in that g e k e n n -z e i c h n e t that an arrangement for determining the rate of heartbeats at a Tachycardia and an arrangement for regulating the initial rate at which this Pulses are generated faster than these heartbeats are intended to be present. 18. Control pacemaker according to claim 17, characterized in that g e k e n n -z e i c h n e t that there are successive time intervals between the pulses differ in the sequence by a predetermined amount. 19. A regulating pacemaker according to claim 18, characterized in that there is no e i c h n e t that there is an arrangement to prevent pulses towards the end of any sequence are generated according to time intervals that are smaller than are a predetermined interval. 20. Control pacemaker according to claim 19, characterized in that g e k e n n -z e I do not believe that the confirmation arrangement operates to confirm a tachycardia becomes responsive to occurrences in succession a predetermined number of times of heartbeats, each of which after a previous heartbeat within occurs a predetermined period of time. 21. Control pacemaker according to claim 17, characterized in that it is not possible to use it c h n e t that there is an arrangement by which pulses are prevented from opposing The end of any sequence will be generated after time intervals smaller than are a predetermined interval. 22. A regulating pacemaker according to claim 21, characterized in that it is not c h n e t that the confirmation arrangement operates to confirm a tachycardia becomes responsive to occurrences in succession a predetermined number of times of heartbeats, each of which after a previous heartbeat within occurs a predetermined period of time. 23. Control pacemaker according to claim 17, characterized in that g e k e n n -z e I do not believe that the confirmation arrangement operates to confirm a tachycardia becomes responsive to occurrences in succession a predetermined number of times of heartbeats, each of which after a previous heartbeat within occurs a predetermined period of time. 24. Control pacemaker according to claim 1, characterized in that g e k e n n -z e i c h n e t that there are successive time intervals between the pulses in of the sequence differ by a predetermined amount.