Ng reset and voltage increasing circuits cardiac autopacer with variable refractory non linear feedback latchi

Claim 2

Electronic apparatus for producing artificial cardiac stimulating pulses comprising: a portable source of electrical energy; resettable means operative in association with said source for generating said artificial cardiac stimulating pulses a predetermined interval after the last reset thereof; said generating means including means operative to reset said generating means upon the generation of an artificial heart stimulating pulse; means for detecting a signal representative of artificial and natural heart stimulation; first means responsive to a detected heart stimulation signal for providing a reset signal for resetting said generating means; means operative in association with a detected heart stimulation signal for inhibiting resetting of said generating means by said reset signal in response to a variable refractory period after the detection of a natural and artificial heart stimulation signal; and means for providing said variable refractory period in response to said detected stimulating signal with a duration which is relatively longer at rates typical of artificial stimulation and which prevents continuous pulse generation in response to detected tachycardia pulse rates but enables continuous pulse generation at more rapid detected pulse or noise rates.

Claim 3

The apparatus of claim 1 wherein said pulse generating means includes means operative to maintain the predetermined interval and the width of said pulse substantially constant despite variation in the load on said generating means.

Claim 4

The apparatus of claim 1 wherein: said means for providing a variable refractory period includes means for produciNg a plurality of output pulses beginning with the detection of each said heart stimulation pulse and continuing for a delay period which increases with the level of said detected heart stimulation pulses whereby natural heart stimulation pulses have a negligible delay period while artificial stimulation pulses have a substantial delay period to produce a relatively longer inhibition for said artificial pulses; and said inhibiting means includes means operative to provide a fixed period of inhibition after the last pulse output of said output pulse providing means.

Claim 5

The apparatus of claim 3 wherein: said variable refractory period providing means comprises a high gain amplifier having a saturation characteristic which produces alternate state saturations of said amplifier from artificial heart stimulation signals, said saturation states lasting for said delay period with each change in said amplifier into and out of saturation producing an output pulse from said detecting means.

Claim 6

The apparatus of claim 4 wherein said variable refractory period providing means further comprises means for producing a unipolar signal representative of the deviation of the output of said amplifier from a noise threshold surrounding a quiescent state of said amplifier with the output of said means for producing a unipolar signal adapted to recommence the inhibiting period of said inhibiting means.

Claim 7

The apparatus of claim 5 wherein said generating means is further characterized by having: a low current push-pull voltage doubler output circuit adapted to produce said artificial heart stimulation pulse at a voltage magnitude substantially higher than the magnitude provided by said source; and means for maintaining said predetermined interval and the width of said artificial heart stimulation pulse at substantially constant values with variation in the load for said artificial heart stimulation pulse.

Claim 8

The apparatus of claim 5 wherein said inhibiting means further comprises: a capacitor; means for charging said capacitor in response to each unipolar signal; means for discharging said capacitor over an interval which defines said inhibiting period; and means operative to inhibit resetting of said generating means whenever the charge of said capacitor is above a selected magnitude. 8 The apparatus of claim 5 wherein said unipolar signal producing means further includes a regenerative circuit to provide consistent unipolar signals in response to each deviation of the output of said amplifier.

Claim 9

The apparatus of claim 1 wherein said means for producing the variable refractory period is characterized by having: a first RC timing circuit; means for imparting a stable charge state to said timing circuit; means for applying to said timing circuit a variable change in charge from said stable charge state upon the detection of each heart stimulation pulse, the gradual return to said stable charge state defining said variable period; a second RC timing circuit with a longer time constant than said first RC timing circuit; means for imparting a stable charge state to said second timing circuit; means for applying to said second timing circuit a change in charge from said stable charge state upon the detection of each heart stimulation pulse; and means for decreasing the change in charge applied to said first RC circuit with each detected signal in correspondence with the charge deviation of said second RC circuit from its stable charge state.

Claim 10

The apparatus of claim 1 wherein: said source has an output voltage which decreases near exhaustion of energy from said source; said generating means includes means responsive to the voltage magnitude of said source for controlling said predetermined interval to partially represent said output voltage magnitude; and means responsive to external activation are provided to cause continuous pulse generation.

Claim 11

The apparatus of claim 1 wherein said supply source is further characterized as having redundant batteries of matched characteristics in parallel and a diode device connected from each said battery conducting to a point forming a terminal of said source.

Claim 12

An electronic heart pacer including the electronic apparatus of claim 1 wherein: electrodes are provided to apply said artificial pulses to said heart and receive heart stimulation signals; and said variable refractory period providing means includes means for providing a relatively longer refractory period in response to detected artificial heart stimulation and a relatively shorter period in response to detected natural heart stimulation whereby signals resulting from recovery of said electrodes from artificial heart stimulation are inhibited from resetting said generating means and tachycardia natural heart beat signals are effective to reset said generating means.

Claim 13

The electronic apparatus of claim 1 wherein: said source has a voltage output substantially below the necessary voltage magnitude for artificial heart stimulation; and said generating means further includes a high efficiency saturating switch means for augmenting the voltage magnitude of said stimulating pulses above the output magnitude of said source to a magnitude compatible with artificial heart stimulation.

Claim 14

Electronic apparatus for producing artificial demand cardiac pulsing for application to heart terminals, said apparatus comprising: means for generating artificial heart stimulating electrical pulses for application to said terminals; said generating means including non-linear feedback means for regulating said pulses to a preselected period and width substantially unaffected by variations in the load across said terminals; means responsive to signals on said terminals for sensing a natural heart beat QRS electrical signal and an artificial heart stimulating electrical signal; means for recommencing the pulse period between each said electrical pulses without generation of said electrical pulse when each said electrical signal is sensed.

Claim 15

Electronic apparatus for producing artificial demand cardiac pulsing for application to heart terminals, said apparatus comprising: means for generating artificial heart stimulating electrical pulses for application to said terminals; said generating means including non-linear feedback means for regulating said pulses to a preselected period and width substantially unaffected by variations in the load across said terminals; means responsive to signals on said terminals for sensing a natural heart beat QRS electrical signal and an artificial heart stimulating electrical signal; means for recommencing the pulse period between each said electrical pulses without generation of said electrical pulse when each said electrical signal is sensed.

Claim 16

The apparatus of claim 14 characterized by said generating means including: an astable multivibrator operating at said preselected period; a one-shot multivibrator producing a pulse of said preselected pulse width upon a change of state of said astable multivibrator; said one-shot multivibrator having said non-linear feedback means and including said astable multivibrator with said feedback means adapted to maintain said pulse width substantially constant with variations in the load for said pulse; and said one-shot multivibrator including means operative to isolate the preselected period of said astable multivibrator from loading effects.

Claim 17

The electronic apparatus of claim 14 further including: a portable source of operating power; said generating means having means to cause the timing of said artificial pulses to represent remaining energy in said source whereby the timing of said artificial pulses is relatively responsive to source energy condition; and said non-linear feedback means including means for regulating the timing to be relatively unresponsive to variations in the load across said terminals to provide an accurate measure of source energy.

Claim 18

Electrical apparatus for generating a train of artificial body muscle stimulating electrical pulses having a potential magnitude greater than the potential of its energy source comprising: a source of electrical energy and providing an electrical potential between first and second terminals thereof; a first capacitor having an associated means for supplying energy from said source to said first capacitor; means for producing a reference signal of potential intermediate the potentials of the source terminals; means for discharging said capacitor in response to the signal on said first capacitor achieving a set relationship to said reference signal, said dischaRging means including; a rectifying device and a capacitor in parallel therewith, said device conducting only during discharge of said first capacitor; a first transistor of one conductivity type; a second transistor of the opposite conductivity type with the emitter, base, and collector of said first transistor connected respectively to said first capacitor at a first terminal thereof, to said rectifying device for conduction from the emitter of said first transistor through said controlled conduction device, and to the base of said second transistor; and with the emitter and collector of said second transistor respectively connected to a first terminal of said source including a connection to a second terminal of said first capacitor and to the opposite terminal of said rectifying device including a connection to a first junction; said discharging means having said first junction connected to said first terminal of said source during discharging of said first capacitor; a second capacitor connected from said first junction to a first terminal adapted for connection to a body muscle; means for charging said second capacitor to the potential of said source during charging of said first capacitor with said first junction at the potential of said second terminal of said source; and means for connecting said second terminal of said source during discharging of said first capacitor to said load at a second terminal thereof.

Claim 19

Electrical apparatus for generating a train of artificial body muscle stimulating electrical pulses having a potential magnitude greater than the potential of its energy source comprising: a source of electrical energy and providing an electrical potential between first and second terminals thereof; a first capacitor having an associated means for supplying energy from said source to said first capacitor; means for producing a reference signal of potential intermediate the potentials of the source terminals; means for discharging said capacitor in response to the signal on said first capacitor achieving a set relationship to said reference signal, said dischaRging means including; a rectifying device and a capacitor in parallel therewith, said device conducting only during discharge of said first capacitor; a first transistor of one conductivity type; a second transistor of the opposite conductivity type with the emitter, base, and collector of said first transistor connected respectively to said first capacitor at a first terminal thereof, to said rectifying device for conduction from the emitter of said first transistor through said controlled conduction device, and to the base of said second transistor; and with the emitter and collector of said second transistor respectively connected to a first terminal of said source including a connection to a second terminal of said first capacitor and to the opposite terminal of said rectifying device including a connection to a first junction; said discharging means having said first junction connected to said first terminal of said source during discharging of said first capacitor; a second capacitor connected from said first junction to a first terminal adapted for connection to a body muscle; means for charging said second capacitor to the potential of said source during charging of said first capacitor with said first junction at the potential of said second terminal of said source; and means for connecting said second terminal of said source during discharging of said first capacitor to said load at a second terminal thereof.

Claim 20

Electronic apparatus for producing variable simulated refractory period demand cardiac pulses comprising: resettable means for generating artificial heart stimulation electrical pulses a predetermined interval after the last occurring artificial pulse or reset thereof; means for detecting artrificial and natural heart stimulation electrical signals; said detection means including means operative to reset said generating means upon the detection of stimulation signals; said detecting means further including means operative to inhibit the resetting of said generating means for a variable refractory interval after the occurrence of each detected heart signal; and means for producing said variable interval with a duration varying in response to predetermined characteristics of said detected natural and artificial heart signals to prevent continuous artificial pulse generation during normal and tachycardia heart rates.

Claim 21

Electronic apparatus for producing variable simulated refractory period demand cardiac pulses comprising: resettable means for generating artificial heart stimulation electrical pulses a predetermined interval after the last occurring artificial pulse or reset thereof; means for detecting artrificial and natural heart stimulation electrical signals; said detection means including means operative to reset said generating means upon the detection of stimulation signals; said detecting means further including means operative to inhibit the resetting of said generating means for a variable refractory interval after the occurrence of each detected heart signal; and means for producing said variable interval with a duration varying in response to predetermined characteristics of said detected natural and artificial heart signals to prevent continuous artificial pulse generation during normal and tachycardia heart rates.

Claim 22

The apparatus for producing variable simulated refractory period demand cardiac pulses of claim 18 wherein said means for producing said variable refractory interval comprises: means for developing a plurality of signals from the detection of each said heart stimulation signal, said plurality of signals spanning a period which increases with the level of the detected heart stimulation signals, said spanned period being longer for artificial signals, and at least substantially shorter for natural signals; means for producing a further portion of said interval upon the occurrence of each of said plurality of signals.

Claim 23

The apparatus for producing variable simulated refractory period demand cardiac pulses of claim 19 wherein: said means for developing a plurality of signals includes an amplifier having a prolonged saturation response to detected artificial stimulation signals and substantially less saturation response to detected natural stimulation signals; and said means for producing a further portion includes an RC timing circuit excited by each of said plurality of signals to leave a stable level of charge to which said timing circuit tends to gradually return; said inhibiting means including means responsive to a range of levels of charge during the gradual return to said stable level for producing a reset inhibition, and to said stable level of charge for producing no reset inhibition.

Claim 24

The apparatus of claim 18 wherein said variable interval producing means comprises: a first RC timing circuit; means for impaRting a stable charge state to said first timing circuit; means for applying to said timing circuit a variable change in charge from said stable charge state upon the detection of each heart stimulation pulse, the gradual return to said stable charge state defining said variable interval; a second RC timing circuit with a longer time constant than said first RC timing circuit; means for imparting a stable charge state to said second timing circuit; means for applying to said second timing circuit a change in charge from said stable charge state upon the detection of each heart stimulation pulse; and means for decreasing the change in charge applied to said first RC circuit with each detected signal in correspondence with the charge deviation of said second RC circuit from its stable charge state.

Claim 25

The electronic apparatus of claim 18 wherein said variable interval producing means includes means for producing a relatively longer interval in response to detected artificial heart stimulation electrical signals and a relatively shorter interval in response to detected natural heart stimulation signals.

Claim 26

Electronic apparatus for producing artificial cardiac stimulating pulses comprising: a portable, exhaustible energy source for powering said apparatus; said energy source having a power output voltage magnitude representative of remaining source energy; means for generating said artificial cardiac stimulating pulses; said generating means including non-linear feedback for regulating the timing of said artificial cardiac stimulating pulses to isolate pulse timing variations from effects other than said energy source; means for producing a substantial variation in pulse timing with source voltage, said variation in pulse timing having a unique polarity of change in pulse rate for a corresponding polarity of change in source voltage; means for sensing natural and artificial cardiac stimulation; means responsive to sensed cardiac stimulation for inhibiting the generation of a pulse and for reinitiating the interval between pulses; and means actuable by an externally applied field for blocking the action of said inhibiting means thereby to permit continuous pulse generation with timing uniquely representative of the energy condition of said energy source.

Claim 27

Electronic apparatus for producing artificial cardiac stimulating pulses comprising: a portable, exhaustible energy source for powering said apparatus; said energy source having a power output voltage magnitude representative of remaining source energy; means for generating said artificial cardiac stimulating pulses; said generating means including non-linear feedback for regulating the timing of said artificial cardiac stimulating pulses to isolate pulse timing variations from effects other than said energy source; means for producing a substantial variation in pulse timing with source voltage, said variation in pulse timing having a unique polarity of change in pulse rate for a corresponding polarity of change in source voltage; means for sensing natural and artificial cardiac stimulation; means responsive to sensed cardiac stimulation for inhibiting the generation of a pulse and for reinitiating the interval between pulses; and means actuable by an externally applied field for blocking the action of said inhibiting means thereby to permit continuous pulse generation with timing uniquely representative of the energy condition of said energy source.

Claim 28

Electronic apparatus for producing artificial cardiac stimulating pulses comprising: a portable, exhaustible energy source for powering said apparatus; said energy source having a power output voltage magnitude representative of remaining source energy; means for generating said artificial cardiac stimulating pulses; means for producing a substantial variation in pulse timing with source voltage, said variation in pulse timing having a unique polarity of change in pulse rate for a corresponding polarity of change in source voltage; means for sensing natural and artificial cardiac stimulation; means responsive to sensed cardiac stimulation for inhibiting the generation of a pulse and for reinitiating the interval between pulses; and means actuable by an externally applied field for blocking the action of said inhibiting means thereby to permit continuous pulse generation with timing uniquely representative of the energy condition of said energy source; said pulse generator including: a source of electrical energy; a first transistor of one type; a second transistor of a second type; a capacitor; means for charging said capacitor from said source; means for providing a reference level which is a function of said source voltage; means for interconnecting said first and second transistors and said capacitor to provide regenerative activation of said reference level less the forward base conduction voltage of one of said transistors; means for interconnecting said capacitor and said transistors to provide discharge of said capacitor during activation of said transistorS; and means interconnecting said capacitor and said transistors to provide regenerative deactivation of said transistors in response to discharge of said capacitor to a predetermined level; the charge and discharge intervals of said capacitor being a function of source voltage whereby variation in both provides a confirmed indiciation of source energy depletion; said inhibiting means including regeneratively operative latching means for discharging said capacitor in response to sensed cardiac stimulation thereby to permit complete discharge of said capacitor regardless of the frequency at which said cardiac stimulation is sensed.

Claim 29

Electronic apparatus for producing artificial cardiac stimulating pulses comprising: a portable, exhaustible energy source for powering said apparatus; said energy source having a power output voltage magnitude representative of remaining source energy; means for generating said artificial cardiac stimulating pulses; means for producing a substantial variation in pulse timing with source voltage, said variation in pulse timing having a unique polarity of change in pulse rate for a corresponding polarity of change in source voltage; means for sensing natural and artificial cardiac stimulation; means responsive to sensed cardiac stimulation for inhibiting the generation of a pulse and for reinitiating the interval between pulses; and means actuable by an externally applied field for blocking the action of said inhibiting means thereby to permit continuous pulse generation with timing uniquely representative of the energy condition of said energy source; said pulse generator including: a source of electrical energy; a first transistor of one type; a second transistor of a second type; a capacitor; means for charging said capacitor from said source; means for providing a reference level which is a function of said source voltage; means for interconnecting said first and second transistors and said capacitor to provide regenerative activation of said reference level less the forward base conduction voltage of one of said transistors; means for interconnecting said capacitor and said transistors to provide discharge of said capacitor during activation of said transistorS; and means interconnecting said capacitor and said transistors to provide regenerative deactivation of said transistors in response to discharge of said capacitor to a predetermined level; the charge and discharge intervals of said capacitor being a function of source voltage whereby variation in both provides a confirmed indiciation of source energy depletion; said inhibiting means including regeneratively operative latching means for discharging said capacitor in response to sensed cardiac stimulation thereby to permit complete discharge of said capacitor regardless of the frequency at which said cardiac stimulation is sensed.