Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
-
This invention pertains to dispensing medical or physio-
logical substances or matter internally and more specifically to
implanted apparatus for dispensing these substances over a long
period of time accoxding to the specific needs of the patient at
the times the substances are dispensed.
2. Description of the Prior Art
A review of prior art practices with regard to dispensing
medical substances internally of the body is given in the appli-
cant's U.S. Patent No. 3,692,027 issued Septembex 19, 1972 to which
reference is made. So far a~ I am aware, my prior P~tent No.
3,692,027 provides the first teaching o~ a sel~-powered de~ice
which can be implanted and which i5 adapted to dispense medical
substances in premeasured doses at specific intervals over a long
period of time. There has appear~d in the June 1973 issue of For-
tune magazine an article describing other continuous diffusion
capsule types of dispensing devices. This article points out and
emphasizes the tremendous need for long term medication dispensing
devices which can provide for dispensing of medication at specific
target organs or target sites. ~he prior art in the area of
diffusion devices is also illustrated in U.S. Patent No. 3,279,996
by David M. Long and Moses Judah Folkman issued October 18, 1966
for a polysiloxane carrier for controlled release of drugs and
other agents. The device of this patent con~ist~ af a
silicone rubber container with the drug being soluble and
capable of diffusing through the silicone rubber to the
outer surface of the container. A further development of
this device was reported in the literature in the Annals of the
New York Academy of Sciences, vol. 111, 1963-64 on pages 857-
868 by Judah Folkman and David Long in which an electrical
~ . " ~"
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1 volta~e is described as being applied to the container and to an
outside electrode, in an attempt to increase the diffusion of
materials through the fibrous scar tissue which is caused to be
thrown up around the container by reason of its being implanted
into the myocardium. The medication is described as being
pulled throuyh the myocardial fibrous scar tissue by means of
iontophoresis. In these adaptations, the medication is in a
eontinuous diffusion state and is not pre.sented in discrete
doses at timed intervals or according to the physiological
needs.
Related to the present invention is the practice of
implanting devices whieh sense heart conditions by meAn~ o~ ~he
eardiae eleetrical activi~y and trigger el~ctriaal pulses ~o
effeet the h~art rate according to the sensed data. These
deviees have generally been cateyorized as "pacemakers" and
their use proves that the human body can accept implanted devices
without endangering human life in the implantation procedure.
They have also provided documentation for the applicability of
feedback in the instance of the demand pacemaker version in
~ which the output is controlled by the pacemaker logic which
makes decisions on the basis of the electrical activity of the
heart. The feasibility of the demand pacemaker for implantation
is documented in the article listed below.
1) Goetz, R.H.; Goldstein, J.V.; Fraterr R.W.M., Berkovitsr
B. ~ "Demand Pacemaking in Intermit-tant Heart-Block",
~ouxnal of the American Medical Assoeiationr Vol. lOr
pp. 657-662, 1968.
2) Nathan, D.A.; Centerr S.; Wur C.; Kellerr W.; "An
c ~
f~ Imp]antable, Synchronou~ ~d~e~a for the Long Term
Correction of Complete He~rt-Block", Circulation, Vol.
XXVII, pp. 682-685, 1963.
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3) Fischler, H.; Barr, I.M. ~ uerback, Yerushalmi S.;
S~ ieoi
w ~ Neufeld, H.N. - "Atrial-Sieb4l~L~ Demand Heart Pacing".
IEEE Transactions on Biomedlcal Engineering, Vol. BME~16,
pp. 6~-69.
A further area of the prior art related to the inven-
tion concerns the various types of sensors some of which are now
commercially available and which can be used to accurately sense
physiological and chemical body conditions. At present, the
output of most of these devices that sense body changes are
recorded and/or acted on by devices external to the body. For
example, glucose detection, pN detection, ionic change detection,
blood pressure ox blood 10w detection, electrical ac~ivik~
detection, respiratory detection, and gastroint~lnal motility
detection all constitu~e ex~s~lng prac~ical types of sensing
apparatus.
It should also he recogni~ed that the prior art has
shown that an implanted device having a battery supply can be
electric~ ly rech~rge~ wi~hou,t having to remove the device.
~ ~e ,7~ e ~a~e~f
Also, my~ow~ ra-tcn* 3,692,027 refers to means for recharging an
implanted medication supply. Thus, both implanted battery and
medication storage recharging are known.
From the foregoing, it can be seen that while the
implanting technique has been perfected in many respects, and
that while both the diffusion device which releases medication
continuously and my own self-powered technique which provides
a means for dispensing medical substances in pre-measured doses
on a continuous basis or at predetermined regular intervals,
no dispensing device or method has appeared in the prior art
which allows medical substances to be dispensed by an implanted
device and according to specific physical requir~ments of the
patient that are determined by the device itself.
SUMMARY OF THE INVENTION
The apparatus and method of the invention is based
on the apparatus being entirely implanted in the body. There
is provided either one or a plurality of sensors, each of which
is adapted to sense a particular body condition at a particular
point in the body. There is also provided a self-powered medi-
cation dispensing apparatus whose operation is made dependent
on evaluation of changes in the sensed data. The dispensing
apparatus and method of the invention can be directed to one or
a plurality of medical substances in powdered, liquid, suspen-
sion, or other dispensable form. The d~cision making capability
of the invention which functions on a basis of chang~s .in the
sensed data, controls when the dispensing appara~us operates and
therefore controls the dispensing of medication according to
the specific needs of the patient at specific times.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a block diagra~ illustrating the basic
components of an apparatus according to the invention;
Figure 2 is a block diagram illustrating the appli-
cation of the invention to cardiac monitoring and medication;
Figure 3 is a block diagram illustrating the appli-
cation of the invention to blood pressure monitoring and medi-
cation;
Figure 4 is a block diagram illustrating applicat.ion
of the .invention to blood chemistry monitoring and medication;
Figure 5 is a block diagram illustrating application
of the invention to dlspensing medicat.ion to the same site from
multiple sources.
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Figure 6 is a block diagram illustrating application
of the invention to dispensing different medications to diferent
sites;
Figure 7 is a somewhat schematic and enlarged diagram
of a minature bellows pumping device useful in the invention;
Figure 8 is a somewhat schematic enlarged view of a
multiple bellows type pump for dispensing the same medication
to the same s.ite but in different quantities and under different
conditions;
Figure 9 is a somewhat schematic enlarged diagram of
a multiple bellows type pump for dispensing separate kinds of
medication to separate sites in different quantities and under
separate controls;
Figure 10 i9 a somewhat schema~ic enlarged clrawin~ oE
a bellows pump with multiple separa~ed chambers ~or di~erent
chambers or sites having a common power source;
Fiyure 11 is a somewhat schematic enlarged view of an
implantable system according to the invention and adapted to
dispense different medications from dif~erent sources under
different controls;
Figure 12 i.s a schematic diagram of the apparatus of
the invention as it might be used with superventricular tachy-
cardias treated with quinidine;
Figure 13 is a schematic sectional view through the
apparatus of Figure 12;
Figures 14 and 14A schematically illustrate a portal
arrangement for replenishing medication to the system;
Figure 15 is a block diagram of the decision making
circuitry;
Figure 16 is a more detailed circuit diagram corres-
pDnding to Figure lSi and
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1 Figure 17 (located on page with Figure 14) i5 a repre-
sen ative timing diagram for dispensing plural doses of medication.
BACKGROUND FOR LATER DESCRIPTION
OF THE PREFERRED 13MBODIMENTS
Prior to describing the apparatus and method which
constitutes the invention, background information will be given
concerning specific and recognized medical problems to which
the invention method and apparatus may be applied. With this
background, the mechanisms and methods later described will be
better understood.
The general concepts behind the applications to be
explained revolve around sensing and evaluation o~ biological
signals that relate to abnormal processes or variations in normal
processes in the body that may be used to evaluat~ the need ~or
release oE the yiven medication, hormone, or other type of
chemical into the body or into speciic organ or target s.ites.
The dispensation of mediaatlon into specific organ sites, by the
means of a small catheter~ may of course allow for small
quantities to be much more potent at the targe-t site without
systemic side effects developing. In additionr the concept of
feedback evaluation controlling or altered release of medica-
tion will allow for an intermittent dispensin~ of the drug which
might handle a problem at much lower doses than iE medication
is given over a sustained period without sensitiv~ regard for
therapeutic needs and the possible development o:E various toxic
and tolerant eifects. For example, an appllcation tha~ w:L11 b~
described later is that of transducing a pressure chanye in the
blood vessels to provide information to the decision mak:ing
capacity of logic and timing circuits in the device which aati~ate
a self-powered pump, to release a given quantity of a blood
1 pressure reducing medication. The decision to dispense the
medication is intended to operate only when the pressure rises
above a certain level. This type of operatlon offers the
opportunity to help overcome some of the undesirable effects
from drugs such as adrenergic blocking agents, ~hich when given
chronically produce untoward side effects, including psycholo-
gical depression and orthostatic hypotension. The same is true
with a variet~ of other blood pressure reducing drugs. In
other applications to be described later, physiological signals
that predict the toxic effect of a given drug can be used by
the device in evaluating the needed medication dispensation.
Thus, the toxic effects can be counterpointed against the
therapeutic need or medication by the logia ~yst~3m of th~
invention.
Involved in the biolo~lcal sensing for blood pressure
or other physiological changes that the device is evaluatirlg,
are possible training of physiological responses, effects or
behavioural modification effects, by means of appropriate
programming of such a device with small logic circuits. The
type of signal detected and usea for processing in the logic
circuits may be either one signal. or a combination of bio-
signals, one or several being necessary ~or the triggering of
the later described pump dispensing device. For example, by
implanting an appropriate device in drug addicts one may monitor
a variety of physiological changes produced by the injection of
a narcotic; that is, respiratory depression measured hy a micro
strain gauge attached to the diaphram, a strain gauge attached
to the stomach or in the upper duodenum to measure gastro-
intestinal mo~i.lity and the type of motili.ty, and a pressure
transducer to measure the increase in biliary duct pressure,
and use the combi.nation of these signals to detect the injection
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1 of a narcotic; the dispensing pump may then release a narcotic
antagonist and/or, for behavioural training, may release a
drug that would cause nausea and vomiting, thus providing for
behavioural modification or avoidance conditioning.
The types of application uses with evaluation of bio-
logical signals according to the invention include: 1) chemical
transducers and feedback such as glucose detection, pH detection,
ionic change detection; 2) temperature, pressure, or mechanical
transduced changes; for example, blood pressure, blood flow
gut motility; and 3) electrical activity as might be measured
in the electrocardiogram or electroencephalogram. In the electro-
encephalogram and electrocardiogram, speoial logic circuits may
be de~ised according to the i.nvention on a miniature basis to
provide ~or analysis o~ abnormal signals or rhythms and then
the dispensation of a given amount of drug into the specific
target organ. For example, with certain cardiac arythmias,
the invention recognizes that it is possible to detect and
evaluate these abnormalities with fairly simple logic circuits
and then to dispense a drug into the pericardial sac in a
similar manner that demand pacemakers now operate.
One of the ~disease types closely related to the inven-
tion is malignant hypertension. Malignant hypertension in the
untreated state has a two-year mortality of 90% and a five-year
mortality of almost 100~. Sympathectomy is capable of reducing
the two-year mortality to 50~ and the five-year mortality to
80~. The newer anti-hypertension drugs have been more effective
than this. What this invention provides is a method for treat-
ing malignant hypertension that is based on sensors inside the
body and medication pumped to various ef~ector si.tes. The
sensors may include 1) blood pressure detecting devices in the
~38~L4
neck and/or in the lower extremities; 2~ electrical activity
from the carotid sinus or aortic body; 3) possible electrical
activity from the sympathetic outflow; and 4) the electrocardio-
gram. Blood measurements allow the mechani~ o~ t~e invention
2 ~ to differentiate, for example, between the d~Ystolic and systolic
ratios. Combination of information from the sensors may be
programmed in micro-miniature logic circuits to provide a series
of treatment decisions based on the individual characteristics
of the patient.
On the effec-tor side, the physician is given a wide
choice with the present invention of attacking the problem of
malignant hypertension in several sites: l) the sympathetic
outflow can be blocked with ganglionic blockers; 2) tho aclronal
outflow or releasing mechanisms can be blocked with ganc~lionlc
blockers; 3) appropriate drugs are available which can be dis-
pensed systematically to block the adrenergic receptors through-
out the body; and 4) another group of drugs known as the vara-
trum viride compounds are available and which may be dispensed
according to the invention to inhibit the pressure centers in
the brain itself. Taking only two of the mentioned examples,
it is now possible to devise effector sites in 1) the sympathetic
chain or outflow and 2) systemic sites via intraperitoneal dis-
pensation. Using four sensors and two effector sites it is now
possible to set up an array of contingencies, only some of which
~,'c~s~c
will be described. For example, iE the ~ e~e blood pressure
i.ncreased beyond a certain point, the systemic circulation,
actually a site in the interperitoneal cavity, may receive a
dose of beta adrenergic blocker antihypertensive medicat.ion;
in addition, by means of carefully monitored rel~ase of drugs
to the sympathetic outflow via a catheter, it is now possible
to increase the effectiveness of the antihypertensive dru~s by
_ g _
~31~Q~
1 blocking this outflow. As discussed previously, this local
application could help to prevent many of the serious side
ef ~ cts of systemic ganglionic blocking medication. Problems
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in ~ h~ may be monitored with neck blood pressure devices
"~ ,~.,
or with the electrical activity from the carotid sinus. Various
features in the contingencies may be based on the normal
exercise patterns of the individualr for example, in persons
who have a heavy exercise load, the logic mechanism of the
invention may be established to re~pon~ ~only after two to three
G~7~ a
or even four hours of increased dys-toli~ pressure thus allowing
~or extended periods of exercise with sliyhtly increased pressure.
Comhinations o the devices shown in the drawings may be used
to supply drugs at the various effector site~.
In one sp~cific adap~at,ion a ~lood pre~sure sen~or
~ s~o/, c~
picks up both the systolic and d~o~e blood pressure levels
which are then amplified, or at least the analog signal is
amplified, and presented to a detector and logic timer system
, .
using microminiature logic systems in which several decisions
are made:
23 1. Is blood pressure above criteria level less than 30% of
the heartbeats over a given period of time? If the answer
to this is negative, then there is no release from the
later described pump system. The reader should keep in
mind that the pump system might operate six times a day,
or alternately, it could operate twelve times a day, thus
medication decisions could be made every two or foux hours
or even in fractions of hours.
2. Is the blood pressure above criteria level more than 30~
of the time? If so, the medication is rele~sed into the
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systemic system.
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3. Is the blood pressure above criteria moxe than 90% of the
time? We woula expect that the decision would be affirmative
only a rare number of occasions, but if the decision is
affirmative then there is a release of another drug, a gang-
lionic blocking agent directly to the sympathetic outflow
in the sacral region and the first five of the thoracic
lumber outflow.
The self-powered dispensing device of the invention
allows for two major changes in the treatment of hypertension:
l) It allows for dispensing of the drug to a selective site
inside the body, thus reducing many of the side ~ffects of more
potent and hypertensive drugs. 2) It allows for a much more
careful titration of the hyoptensive efects of the drugs, thus
cutting down on the number of unwarranted hypotensive episodes,
especially those associated with postural hypotension. One
means by which this may be accomplished is by selecting the
drug used for its hypotensive effects for shorter duration of
action, thus allowing for blood pressure feedback to regulate
dosage.
One notable example of the foregoing is in the treat-
ment of severe hypertension. Currently the drug most often
used in the treatment of severe hypertension is guanethidine,
which is a lony-acting drug that tends to accumulate in tissues
and is excreted slowly. Leaving off a dose of this medication
w~uld not have a major effect for several hours, thus the potent
side ef~ects could continue ~or a considerable p~r.iod of time.
Such drugs as bretylium, a short-acting hypertensive agent, have
now been abandoned because of their potent side effects and poor
absorption after oral administration. These effects may, how-
ever, be titrated in the self-powered dispensing device of the
invention. In addition, other dru~s similar to this compound,
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for example sethanidine, (l-bensyl-2, 3-dimethylguanethidine)
and other congeners may be used to a much better advantage by
means of selective titration which lends itself to the apparatus
and method of the invention.
The other group of drugs that increase efficacy depend
on the selective ability of the device of the invention to dis-
pense medication in a particular site and which group includes
the ganglionic blocking agents such as hexamethonium and related
compounds. Blockade of the sympathetic ganglia has a marked
interrupting effect on the adrenergic control of arteriols and
resul~s in vasodilation and improved peripheral blood flow o~
vascular beds and a fall in blood pressure. Par~ o~ the potency
of these drugs is related to the low ratio o~ preganglionic
axons to post-gangllonic axons. ~hu.s, ganglionic block has a
very potent effect. rrhe major difficulty with the ganglionic
blocking agents is a non-selective effect on both parasympathetic
as well as sympathetic ganglions. Again, this group of drugs
is poorly absorbed from the gastrointestinal tract, and there
is a limited ability of these quaternary ammonium ions to
penetrate cell membranes in general. By directing the outflow
portal of a polyethylene catheter from the dispensing device of
the invention to the sacral ganglion and to the first four
ganglia of the thoracolumbar outflow the physician may selec-
tively block blood vessels in large muscle of the extremities
without major effects on the gastrointestinal tract, genito-
urinary system, or the heart and lungs.
Cancer is another problem that may be helped with the
invention's method and mechanism. For example, there may be a
need to dispense different types of drugs to different body sites
depending on the site vulnerability. The bi- or tri-partite
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1 bellow bags, later described, may be used for this purpose. In
other applications, the radio-activity of certain radio-active
anti-cancer compounds may be monitored and the drug dispensed
dependent on the radio-active concentrations in a given cancer
site.
Another use may be in peptic ulcer or gastric ulcer.
For example, the pH may be monitored in the stomach accordiny
to the invention and the antrium of the stomach may be bathed
in an anti-cholinergic drug. Another use may be to bathe pain-
ful spinal dorsal nerves with medication in nerve injury trig-
gered externally by the patient but with the availability still
controlled by the invention's timing anc1 logic circuits to
prevent overdose. In this case, the patient's capaci~y to
perceive pain would becorne the sensor. He would activAte a
reed switch to signal the device. With kidney stones, an outflow
catheter may be placed into the kidney pelvis itself, monitored
and used to change the pH of this area to dissolve the stones.
Certain forms of epilepsy or perhaps several forms of mental
illness may be more effectively treated with intraventricular
2~ medication or minute doses to a specific brain site. This
medication in the case of epilepsy may be triggered by abnormal
electrical activity. Other abnormal brain conditions may be
treated by trlggering off abnormal slow waves (in the awake
state) or by programs to maintain certain forms of electrical
activity such as alpha waves or certain sub-cortical rhythms.
It, of course, should be understood that any of the central
nervous system applications could only proceed ater years o
careful experimentation.
In the case of certain spastic vascular disease such
as Berger's or Raynard's disease, it now appe~ars feasible with
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1 the present invention to accomplish a periodic lumbar or cervical
sympathetic block with medication applied to this area. Medica-
tion may be applied to the artery itsel~ by implanting the out-
flow at the time of vascular surgery. Medication would be dis-
pensed dependent on blood flow sensing.
Congestive cardiac ailure may be detected with sensors
that pick up venous pressure and cardiac electrical activity,
and controlled with diyoxin fed by catheter directly to the
pericardial sac. In other conditions, depending on the results
of extensive research, vasodilators may be dispensed to the
pericardial sac by external patient control on the basis of
angina or other perceived or sensed difficulties by the patient.
Finally, there are a variety of cardiac conclition~,
especially cardiac arthythmias, that may be treated by dispensin~
medication into or through the pericardial sac in response to
abnormal electrical signals from the heart. For example, the
device of the invention may dispense quinadine in the supra-
ventricular tachycardia condition based on the electrophysio-
lo~ical activity of the heart. This example is later disclosed
to demonstrate the present application of the concepts describedabove in a specific device whose operation can be fully docu-
mentea .
In summary, many potential applications present them-
selves immediately and while many years of work will be required
by many persons to fully develop the invention in all its
ramifications, the basic concept is also immediately reco~nized
as practical and useful. Those skilled in the art will reco~nize
that the individual components required and the individual method
steps required have been separately proven in other medical
environments. It is the present invention, however, that combines
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1 such components and steps together to accomplish results and
functions not heretofore achieved.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
_______________.__~__ ___________________
The invention will first be explained in a broad
context and in relation to certain applications following which
reference will be made to construction details of specific
components for practicing the invention, then finally one de-
tailed application will be presented.
Figure 1 illustrates in block and schematic diagram
form the basic components of an implantable system according tothe invention. In particular, there is provided a micro-power
~ource 28, a medieation storayc 29, a sensor 30, a dispenser
control 31, and a dispenser 32. All of the components except
sensor 30 are contained in an appropriate housing 33 which is
implanted in the body of the persons being treated. Power for
the system is pro ided by a ~uitable micro-power source 2B such
e ~e~ e~/
as described inrUnited States Patent 3,692,027. The purpose
of the sensor 30 in each instance is to sense some type physio-
2~ logical, chemical, electrical, or other condition in the bodyat a particular site, and produce data which corresponds to the
sensed condition at the sensed site. This data, according to
the invention method, is then sampled and evaluated by an
appropriate dispenser control 31, e.g., a logic circuit, and
depending on whether the sensed data is or is not indicative
of a need for medication, the dispenser control 31 will op~rate
in a manner to cause the dispenser 32 to either remain off or
to be operated to dispense some precletermined amount of medica-
tion from the s~orage 2~ accorcling to the patient's neecls.
~eferring next to Figure 2, there is schematically
illustrated a more specific and somewhat more complex applicati.on
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1 of the invention to cardiac monitoring and medication. The
micro-power source, while not shown for simplification, should
be treated as part of the Figure 2-6 systems. In the application
of Figure 2, there is provided medication storage 40 and an
electric potential sensor 41, such as employed in electroence-
phalogram and electrocardiogram examinations. While indicated
as a single sensor, sensor 41 could comprise plural, e.g.,
three or more, sensors. The sensed information is directed to
an appropriate logic circuit 42 which is designed to screen the
sensed data for key factors. Since logic circuits as such are
known and within the skill of the art to design, the description
in general will speak more to the medical aspects than to the
precise details of the circuitry, althou~h a morc complete
circuit disclosure will be pro~ided in one example to be pre-
sented later.
With further reference to Figure 2, it is known that
sensed electric potential data such as obtained in electro-
encephalogram and electrocardiogram examinations will reveal a
plurality of factors. The assumption on which Figure 2 is based
is that there are three ~actors A, B and C, which can be screened
out and matched in appropriate subsidiary logic circuits 43, 44,
45 against normal limits. For example, subsidiary circuit 43
can match factor A as to whether it is or is not within normal
limits (WNL) and produce a "no" or a "yes" ou~put accordingly.
Subsidiary circuits 44 and 45 can be designed for similar
~unctions with respect to factors B and C such that if factors
A, B and C are all outside normal limits an output is produced
at junction 46 and which can be used to control the dispenser
~7. Other combinations are possible. All of the components
~xcept the sensor shown in Figure 2 should be noted as being
enclosed in a suitable implantable housing 48.
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To illustrate a ~urther application, reference is made
to Figure 3 which is directed to a blood pressure monitoring and
medication system. In this application~ there is provided a
pressure transducer 51 which is connected to an appropriate
logic circuit 52 contained in an implantable housing 50 and
which is designed to make decisions on the basis of systolic
and diastolic characteristics. If the blood pressure is not
within the defined limits a "no" output is produced and which
is used to operate a suitable dispenser 53 having medication
selected from storage 54 to reduce the pressure.
In Figure 4 a ohemical monitoring systems is illu-
strated. In this embodiment a suitable chemical level sensor
60 is employed and which, for example, may s~nse pH chancJes,
ionic change~, glucose level or other body ch~mi~try factors
susceptlble to sensing. The sensor 60 is connected to an appro-
priate threshold discriminator and logic circuit 61 which in turn
is connected to a medication dispenser 62 and all of which
components except the sensor are contained in a suitable implant-
able housing indicated by 63 which also houses the~storage 59.
In this application, the logic circuit 61 determines whether
the sensed chemical f`actor is or is not within an acceptable
threshold and, if not, operates the medication dispenser 62 to
bring such factor within an acceptable threshold.
Making reference next to Figure 5, there is shown in
block diagram form an application of the invention wherein
dosages of the same medication may be dispensed from di~ferent
sources. In this embodiment, the sensor 64 is connected to
appropriate logic circuitry 65 which controls periodic sensing,
evaluation of the sensed data and dispensing of medication ~rom
a common medication storage 66 through a dispensing means 67 or
a separate dispensing means 68. For example, dispensing means
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1 67 may constitute a low volume, regularly dispensed medication
whereas dispensing means 68 may be used for supplementary medi-
cation at the same treated site.
In Figure 6, the sensor 70 is connected to the appro-
priate logic circuit which controls a dispensing mechanism 72
for dispensing from a drug storage 73 having, for example, drug
A. Circuit 71 also controls the dispensing mechanism 73 for
dispensing from an alternate drug source 74, for example, drug
B. In this application it can be seen that different medica-
tions can be dispensed to the same or different treated sites
with one medication being for one purpose and another medica-
tion being for another purpose. Housing 76 encloses the apparatus~
Fxom the foregoing description, it can he seen that
the various applications of the invention will each re~uire appro
priate timing and sen~ing devices, appropriate circuitry for
evaluating and making decisions about the sensed data, and appro-
priate dispensing devices for dispensing medication subject to
the evaluation of the sensed data. Implantable sensors for a
great variety of purposes are well known and those skilled in
2~ the art will quickly appreciate their applicability to the
broad concept embodied in the present invention. Those skilled
in the art will also readily ascertain other types of implantable
sensors which are suited and the required parameters for other
types of sensors.
Considering next the type of logic circuitry required,
given the concept of the invention, the design o~ such will be
readily apparent to those skilled in the art. In general, the
logic circuitry will be of a type in each application suited to
receiving sensed data from a sensor, e.g., a transducer, in a
form corresponding to the particular application, e.g., pressure
~L~3~ 4
1 data~ chemical data, electrical data, et cetera, and producing
an output depending on the data evaluation. In some instances,
as previously noted in connec~on with Figure 2 there may be a
plurality of ~utput data on a single output which can be screened
by different subsidiary circuits for different data, e.g.,
factors A, B and C, as in Figure 2. Miniature logic circuits
of the kind required by the present invention may be found in
both electronic design books as well as in medical literature,
e.g., designs for demand pacemakers. Those skilled in the art
will also readily appreciate the fact that the present inven-
tion is of such wide scope that the logic circuit designer isgiven a wide choice in the types of circuitry which may be used
to perform the logic functions.
Another important aonsideration concerns the implanta-
bility of the sensor employed, the implantability of the housing
which houses the medication storage and dispensing apparatus and
the implantability of any catheter or other device employed to
discharge the medication at the treated site. Since sensors,
particularly electrical sensors, long term implanted diffusion
devices, and the like, have all been used and the implanting
problems are well known, th:e parameters required for implanting
are considered known to those skilled in the art. Also, since
pacemakers have been implanted, the general parameters for
implanting a housing of the type required by the present inven-
tion is also well known. The long term discharge of medication
internally throuyh implanted catheters, and the like, fed by
external sources of medication is also a current practice. Thus,
tissue growth problems, tissue blockage problems, and the like,
of the lcind encountered in prior practice~s are contemplated by
the present invention and the same technology previously developed
will be useful in the present invention.
Each application of the invention requires means for
er~6~
storing a treating substance under pressure in ~4~e~e~, liquid,
or other dispensable form, means for pumping or otherwise re-
moving predetermined portions from such storage and means for
directiny the measured dosage to the appropriate organ or site
best suited to receiving the dosage. The amount of pressure
may vary with the medication because of different viscosity,
dose sizes, etc., and many arrangements known in the pumping
art will suggest themselves. For example, the medication may
be enclosed in an elastic sack by introducing an inert gas
within the storage area to assert pressure.
The mosk immediately available device suited to the
inve~tion fox stori~g and dispensing medication is illustrated
$~ Ove ~e~ f~" e~/ ~S~,
in my?p~ r Patent No- 3,692l027. For example, 3uch a device
as shown in my prior patent may constitute the dispenser 32
illustrated in Figure 1 and the dispenser control 31 in Figure
1 may include a switch device connected so as to connect and
disconnect the battery which is used to power the device of my
prior patent. In this application, the sensor 30 of Figure 1
senses the particular condition at timed intervals and the
dispenser control 31 of Figure 1 causes the dispenser mechanism,
such as illustrated in my prior patent, to either operate or
not operate according to the evaluation and decision based on
the sensed data. Appropriate controls are preferably provided
for in the circuit logic to prevent overdose if the sensed
physiological change does not occur quickly enough in response to
the medication dosage, e.g., appropriate timing delays or dose/
time functions.
The invention readily lends itself to a variety o~
dispensing mechanisms. Mention has already been made of the
- 20 -
1~380~4
1 mechanism described in my ~bove mentioned U.S. Patent No.
3,692,027. Another mechanism for pumping fluid medication is
shown in Figure 7. In Figure 7 there is shown in a highly enlarged
fo~n a housing 80 mounting a piston 81 secured to a bellows con-
tainer 82 made of polyvinyl or other suitable material. A rod 83
attaches to piston 81 and is caused to move inwardly by an appro-
priate solenoid 84 and to move outwardly by an appropriate spring
85 acting against a head portion 86 as schematically represented
in Figure 7. Solenoid 84 is, of course, controlled by an appxo-
priate logic control as previously explained. The bellows 82
receives medication through an inlet tube 87 and a one-wa~
valve 88 and discharges such medication through a one-way valve
~9 and a discharge tube 90. Xt ~hould, o course, be under~tood
that the pump structure sho~n ~n F~guxe 7 wiil in practice be
; contained in the implanted housing previously referred to and
has the particular advantage of not requiring a high friction
producing seal between piston 81 and housing 80 since all
medication will be sealed and confined to the interior of bellows
82. Bellows pumps as such are known and proven.
One problem co~non to man~ t~pes of physical disabi-
lities is the need to dispense a daily average dose, e.g., insulin,
on a regular basis and to dispense intermittently dosages for
short acting drugs, e.g., insulin, when need arises. Figure 8
schematically represents a device suited to this requirement. In
particular, cam 100 is driven by a suitable micxo-power motor
such as shown in my above mentioned U.S. Patent 3,692,027 and which
is arranged to be energized through an appropriate logic circuit,
not shown. Rotation of cam 100 engages roller 101 and forces
arm 102 to move piston 103 which cau-,es the bellows 104 to dis-
charge from the drug storage area 105 a predetermined dosage
-21-
3~
previously obtained from a drug storage 106. As cam 100 rotates
and after discharge bello~s 104 retracts and refills the chamber
105 at a suitable time the control for cam 100 causes it to
stop. Appropriate one-way valves 107 and 108 control the intake
and discharge. Such a cam driven arrangement may thus provide
the required daily average dosages. For intermittent additional
needs, a solenoid 110 is connected to the appropriate logic
circuit, not shown, and when energized will move arm 111 and
operate a piston 112 to provide a lesser amount than is obtained
by cam 100 so as to provide a smaller dosage. Solenoid 110 is
de-energized at the end of the discharge stroke and spring 113
causes the storage area 114 to refill.
In Figure 9 there is indica~ed an arr~ngement eor
discharging two di~ferent types o~ medication. In Figure 9,
cam 120 and solenoid 121 should be considered similar in their
operation to the cam and solenoid operations previously expla.ined
in connection with Figure 8. In the Figure 9 application, the
cam 120 operates on the bellows 123 and solenoid 121 operates on
the bellows 124. In the Figure 9, as well as in the Figures
7 and 8 dispensing arrangements, power for the respective drive
members, e~g., rod 83, cam 100, is provided by the previously
mentioned micro-power source. One type of medication, e.g.,
a long acting drug, may be stored in one storage reservoir 125
and a separate medication, e.g., a short acting drug, may be
stored in a separate storage reservoir 126. Thus, one drug
source may be dispensed by use o~ solenoid 121 and another drug
source may be dispensed by the use of cam 120. It will, of
course, be understood that appropriate one-way valves and
other features of known mechanical construction may be employed
even though not shown or specifically explained.
- 22 -
~D3~
7 In Figure 10 there is shown a reservoir arrangement
comprising a bellows with two compartments 130, 131 housed in
a common housing 132 and operated by a plunger piston 133. From
the drawings, it can be seen that this arrangement, like that
shown in Figure 9t provides for dispensing two or more types of
medication to two or more body sites. The Figure 9 arrangement
allows such medication to be dispensed to two sites at different
pressures using two power sources whereas the Figure 10 arrange-
ment provides for the medication to be dispensed to two or more
sites at unequal pressures using only one power source. In
addition, the multiple chamber bellows of ~igure 10 provides for
a two or more drug dispensing capability without the greatly
increased friction of more cylinders and piYtons. The bellows
chamber in addition to its se~ling functions al.lows for a variety
of options at the time of implanting suryery simply by substitu-
ting various bellow configurations in the pump. This means that
the surgical facility does not have to maintain many types of
moxe expensive total pump configural changes. It is antici-
pated that a large variety of bellow shapes and sizes will be
2~ found useful and which can be substituted in the pump cylinder
for a multitude of treatment purposes.
In Figure 11 there is schematically shown a system of
a type which corresponds with the type of application diagram
in Figure 6. ~lere again it should be understood that the
schematic diagram in Figure 11 would, in practice, correspond
to a device of substantially less ph~s.ical size. In particular,
there is represented in Figure 11 a housing 150 having appro-
priate suture anchors 151. Within the housing 150 there is
provided an appropriate compartment 152 for holding some pre-
determined amount of medication intended to be released over a
- 23 -
~3~ 4
long term for a chronic situation requiring regular dosages whose
size can be predetermined and scheduled. The compartment 153
represents a storage area for special medication such as might
be required by unusual and transient conditions in a specific
patient. The previously mentioned evaluating and control cir-
cuitry is indicated as being confined in a separate compartment
154 and which is connected to an appropriate sensor 155 located
within the body being treated but external of the housing 150.
For the ~imed medic,atioO/a micro-powered unit 160 of the type
~~e ~e" ~ e
shown in my~ 4~ Patent No. 3,692,027 is controlled by the
circuitry in compartment 154 and when indicated by evaluation
o~ information coming from sensor 155, unit 160 turns on and
rotates the cam 161 thus driving the cam peaks ayainst roller
180 attached to the shaf~ of piston 162 80 as to discharge the
medication confined in the storage area 152 through an appro~
priate discharge tube 164. During discharge the flap valve 170
closes as piston 162 moves to the right in Figure 11 and a sliding
cylindrical valve member 171 moves upwardly in Figure 11 so as to
allow communication between pipes I75 and 176. As cam 161 con-
tinues to turn roller 180 continues to ride on cam 161 by reason
: of spring 181. Flap 170 opens, sliding ~alve 171 moves down and
a new charge is stored in the storage area 163. Portals 158,
159 p.rovide for refilling.
When there is a demand for special medication as
determined by sensor evaluation with the logic circuitry in
compartment 154, solenoid 190 is energized which causes piston
191 to move to the left in Figure 11 against the tension of
spring 1920 Ylap valve 193 closes, sliding valve 194 rises as
shown in Figure 11 and pipes 196 and 197 are placed in communi-
cation to allow discharge through pipe 164. On the return stroke
2~ -
~3~
1 sliding valve 194 moves down, flap valve 193 opens and a fresh
charge of the special medication is drawn into the storage area
200. Thus, by energizing and de-energizing the power unit 160
the treated body can be provided with the periodic timed medi-
cation and by energizing and de-energizing the solenoid 190,
the treated body can be provided with the special medication.
There is next given a more detailed disclosure directed
to a cardiac pump mechanism to dispense medication for prevention
of recurrent tachycardias. As background, it should be noted that
~ quinidine is given on a chronic basis for the prevention of re-
currences of atrial fibrilation and flutter as well as supra-
ventricular tachycardias not due to digitalis toxicity. Quinidine
is also effectively used, as well as procainamide, in prevention
of recurrences of ventricular tachycardia. Quinidine ls also
used to prevent recurrences of ventricular fibrilation except
when ventricular fibrilation occurs during complete heart block
in which case it is contraindicated. A discussion o~ treatment
o~ caxdiac arrythmias can be found in "Drugs used in the Treat-
ment of Cardiac Arrythmias" in Treatment of Heart Disease in
the Adult, 2nd Edition, Rubin, T.L.; Gross, Ho; Arbeit, S.R.,
Lea and Febriger, Philadelphiat pp. 297-324, 1972. One of the
difficulties in using these ~rugs is that the therapeutic index,
the ratio of therapeutic dose to toxic dose, is quite low. The
pump feedback system of the invention is, however, adapted to
carefully monitor the state of the heart and toxic manifestations
of the drug and maintain the drug dosage at a level designed to
minimize, if not eliminate, complications attributable to the
medication. Thus, the device and method of the invention allows
more general use of these medications in what are quite severe
and life-threatening conditions of the heart. The invention is
- 25 -
~.~3~
1 directed to what is needed, namely, a feedback evaluation system
that will provide for the maximum needed therapeutic dose that
can be maintained below the toxic manifestations of the drugs.
The described goals can be accomplished by monitoring
the disease condition and regulating the medication to treat the
condition according to the invention and yet steering clear of
the toxic manifestations of the drug by monitoring and regulating
the dose in relationship to these manifestations also. The
disease entity to be treated as an exa~ple is the supraventri-
cular tachycardias. The present example is dire~ted to counter-
pointing the heart rate against the toxic changes produced by
~uinidine, that is widening of the QRS Complex (a component of
the electrocardiogram). The dose of ~uinidine can thus be moni-
tored by use o the invention and reduced when there is prolonga-
tion of the QRS complex which occurs as the dose of quinidine
begins to reach the threshold for toxic effects.
Figures 12 and 13 demonstrate the basic construction
and operation of the device to be used with supraventricular
tachycardias treated with~dispense~quinidine. The pump motor
2 O a~ o ue ~e o ~e ~ 6~.S~.
210 is of the type shown in my~Patent 3,692,027 an~ is set to
turn the equilateral cam 211/ e.g., eight or more revolutions
per day, thus providing a total of 24 potential cam pump
activating contacts with the roller 230 which operates piston
212O Thus, the pump can potentially operate every hour of the
day providing for 24 potential doses per day. Using this
paradigm provides the following options, if one operates on a
two-hour dispensing schedule, that is dispensing medication
every two hours unless altered by decisions based on evaluation
of the sensors ~the two-hour schedule is accomplished by turning
off the pump motor 210 every other hour). 1. The mechanism
- ~6 -
~.~3B~4
1 would dispense evexy two hours as an average dose timing. 2.
Depending on the feedback evaluation, it may suppress a dose of
medication for two hours thus leaving a four hour interval
between doses when this is indicated. 3. Extxa doses can he
dispensed on a one hour schedule if needed. In actual operation
the movement of pump motor 210 will turn the cam 211 and dispense
the first dose. Then the timing mechanism cuts off the mechanism
for one hour unless conditions require that an extra dose of
medication be provided and in this case the mechanism is designed
to continue to operate for the next hour to provide an extra
dose. Thus, under normal operating conditions, the mechanism
will provide 12 daily doses every two hours. Should toxic
conditions of quinidine maniEest themselves, th~n the mech~nism
may be cut off for su~ficient time to increase the interval
between medications to four hours.
In actual practice with a supraventricular tachycardia,
the electrodes 250 shown in Figure 13 on the heart itself pick
up electrical activity of the heart and conduct the heart signals
to amplifiers in the electronic package by wires 251 embedded in
2 the catheter 248. An electronic logic recognition program
provides for identification of the QRS complex and another pro-
gram subsequently quantifies the QRS period and R-R interval as
described in relation to the chart shown in Figure 17. Opera-
tionally, the cardiac frequency (R-R interval) is monitored and
averaged for each hour over the 24 hour period and stored in a
register. The lowest frequency average for an hour during the
24 hour period is compared with the lowest frequency hour from
control periods as to whether this has increased by 10 to 20
percent over criteria control levels which criteria are set at
time of implantation. Thus, if the frequency has increased by
- 27 -
1 20 percent, then the mechanism will provide three extra one
hour doses every 8 hours for the next 24 hours. The decision-
making control logic in the system provides for this operation.
The contrasting concern, that of quinidine toxicity, is monitored
by the QRS period. The QRS period is sampled and evaluated each
hour and if it increases over criteria levels (% of control~ or
if premature ventricular contractions develop (indicated by very
wide QRS complex over 150% of control) especially with the
quinidine effect controlled, then the next dose period is
tO suppressed by cutting off the power to the pump motor 210 and
secondly stops the extra dose for that 8 hour period that is
currently operational because o~ the criteria provlded for in
the first series of ~eedback optlons.
~ he chart depicked in Figure 17 is explained as follows:
Condition I = Normal operation-pump operates every two hours
on even hours.
Condition II = Cardiac frequency has increased by 10-20% which
actually means the R-R interval has decreased
by 10-20~. In practice, the hour with the
2~ lowest frequency for the previous 24 hour day
is co~pared with the control value to ma~e this
decision. Then, if this 24 hour lowest hour
frequency is 10-20~ higher than control, the
logi.c provides for three extra doses the next
day given every 8 hours at 1, 9, and 17 hours.
Condition III - The sampled QRS period over the past hour is
greater than criterion levels on the following
basis; the QRS complex period is sorted on the
basis of p~rcent of control value and g.iven a
3Q weight in the following schedule:
1) 110% or less than control value given weight
of zero;
- 2~ -
3~
- I 2) 110-120~ greater than control value given
weight of one;
3) 120-130% greater than control value given
weight of two;
41 130-150% greater than control value given
weiyht of eight;
5) Greater than 150% of control valile indicates
ventricular premature contraction and is
given a variable weight of eight or sixteen.
If over the hour, out of the 256 sampled QRS
periods the weights add up to 256 or greaker,
then the pump is turned off ~or th~ next even
hour op~ration ~nd ~econdly stops the extra
dose for that eight-hour period that might be
currently operational because of criterion
provided for in condition II. Thus, if the
hour 4 dose was deleted, then the dose pro-
vided for at hour 9 would be deleted also.
Other aspects of Figures 12 and 13 that require explana-
tion are the three input portals 252, 253, 254. Input portal
252 represents an eight position rotary switch and a needle
contact. The rotary switch and needle contact operates by use
of a solid core needle, not shown, with a round to triangular to
round O.D. (outside diameter) tip sectiOn which is inserted into
portal 252 which has a mating triangular hole as shown. Opera~ion
of the switch is accomplished by turning the needle through one
to ~ight of the various positions. Contact to the switch function
are through contacts on the three triangular surfaces o the
needle approximated to the triangular hole contacts. The leads
to the needle triangular surface are conducted down the long
axis of the needle and are shielded by a suitable isoelectric
~ 2~ -
material. Position No. 1 of the rotary switch provides for
battery recharge through the needle contacts. Position 2 pro-
vides ~or monitoring the electrocardiogram from the implanted
electrodes. Position No. 3 provides for stimulation througn the
cardiac electrodes if pacemaking functions are needed. Position
No. 4 provides for contact with the logic system for calibration
of the logic of the cardiac response parameters. Position No. 5
provides for monitoring the logic output and number of doses per
day. Position No. 6 provides for cutting off of the entire
system. Positions Mos. 7 and 8 are for future options.
Catheter access portal 253 is a bypass catheter inlet
and provides the following functions: (1) It allows the
physician to exert increased pressure if mechanical block occurs
in the catheter. (2) It allows the physician to introduc:e a
wire stylete if mechanical block occurs in the cathèter. t3)
It allows the physician to introduce additional drugs into the
pericardial sac if needed. The catheter access portal operates
in a manner best explained by reference to Figures 14 and 14A.
A hollow bore needle, not shown, with a round to square to round
:20
O.D. tip section is inserted through the patient's skin with the
aid of protuberance 306 and thence into the square hole 303~
The square needle segment engages the sides of the square hole
303. Rotating the needle about its long axis rotates pinion 302,
which is meshed with and rotates partial ring gear 301. When
partial ring gear 301 has rotated to its counterclockwise limit
portal 307 is in line with the I.D. ~inside diameter) of the
needle allowing access to the catheter 304, and the pump output
port 305. "O"-rings 308 and 309 seal the port .in both opeh and
closed configuration. Pinion 302 is held in position by top
plate 310. In Figure 14, the external casing of the device is
represented by line 311.
- 30 -
~.~3~
1 For purposes o~ replenishing medication, the input
portal 254 is employed. Since the introduction of pressurized
~ replenis,hing medication has been previously discussed in my
,~,"~,~,,.','! ' ~o6~e ~,0~7 e ~ ~S~ .
Patent 3,692,027 and a suitable portal struc~ure described, no
further detailed description o~ this operation or of the refill
portal is deemed necessary.
Figure 13 shows in ~urther detail the bypass system
with the details of the attachment of the catheter system to
the pericardial sac. 0-rings 255 beneath the entry portal are
provided for sealing purposes. A one-way valve 256 in the
catheter leading to the pump provides ~or block o~ any increased
pressure in the bypass system into the pump mechanism. The
catheter system is sewn into the pericardial lining with a ring
247 embedded in the catheter 248 having both a uni,form ca~heter
section and an appended expanded catheter section in the form o~
a trumpet 249. The expanded catheter diameter provides for
increased surface area and reduces any blockage due to the
fibrosis around the exit portal to the catheter. Also shown
adjacent catheter 248 are leads 251 leading from the pair of
sensing electrodes 250 to the amplifier and logic system~ These
are actually embedded in the catheter and provide additional
support for the catheter. The electrodes 250 and attached wires
are emhedded in a polyvinyl shield after their exit from the
catheter.
A block diagram describing the general operation and
decision making involved in control of the cardiac medication
pump is illustrated in Figure 15. The depicted "electrode
sensor" and "amplifier" are intended to represent standard,
devices such as are used in present cardiac pacemaker circuits.
The remaining portion of the block diagram of Figure 15 is the
"brain" of the system and provides control to the "pump" based
- 31 -
~3~
on the presence of conditions I, II or III, as previously
described. The type and nature of components required for
the ~igure 15 circuit are generally known ana have been else-
where indicated. ~herefore, since Figure 16 represents a more
detailed description of Figure 15, it is believed those skilled
in the art will readily understand the circuitry and operation
depicted in Figure 15 after reading the description to follow.
The description now turns to a description of Figure
16 which constitutes a logic flow c ~ t suited to the application
related to Figures 12-15 and 17. Since the components in
Figure 16 are identi~ied and are known to those skilled in the
art and their relation in the circuit is shown, the description
will next concern itself primarily with the operation o~ the
circuitry of Figure 16. The "Possible QRS-Complex Detector"
with output at ~a) detects the beginning and end of all "possible"
QRS-complexes. The start of a "possible" QRS-complex is detected
by the "Possible QRS-Complex Start Detector" with output at (b)
and the end of a "possible" QRS-complex is detected by the
"Possible QRS-Complex End Detector" with output at (d). The
decision of whether the "possible" QRS-complex that is detected
is a "true" QRS-complex is made by the "True QRS-Complex Detector"
with output at (c). The outputs at (c) and (d) are then combined
through an And Gate with output at (e). This output (e) represents
the end of a "true" QRS-complex.
The QRS-complex is analysed in two different ways:
~1) Measurement of the time period of the QRS-complex; and (2)
Measurement o~ the time pexiod between two consecutive QRS-
complex, i.e., R-R interval.
The measurement of the time period of the QRS-complex
is accomplished through the "Per Cent Control-Time Classifier".
- 32 -
1 The signal at (b) is the signal to reset and then start this
classifier which classifies the time period of a QRS-complex
into one of five time intervals: (I) 110~ or less of control
time, (II) 110% of 120% of control time, (III) 120% to 130~ of
control time, (IV) 130% to 150% of control time, or (V) 150
of greater of control time. The control time is the time
period of a normal QRS-complex for the given patient. The
signal at (f) occurs at the end of a "true" QRS-complex once
every 256 times an hour. The pulse at (f) is the signal to add
to the "Accumulating Counter For QRS Time Period". Depending
on the percent of control time classification o~ the QRS-complex,
this counter is incremented by 0, 1, 2, 4, 8, or 16 counts.
~ach classification adds a se~ number to the courlter. Class-
ification (V) has the additional opt.ion of having its count
value changed to 4, 8, or 16 through "Memory Latch Control 1".
Thls memory latch control can be set through the previously
mentioned externally accessible rotary switch 252, not shown
in Figure 16 but shown in Figures 12 and 13. If the count on
the "Accumulating Counter for QRS Time Period" exceeds 256 in
an hour then the output at ~g) is a logic "one" otherwise (g)
is a logic "zero"~
The measuremen-t of the R-R interval is accomplished
by the "R-R Pulse Generator" which selects two consecutive
"true" QRS-complexes once every 256 times an hour and outputs
a logic "one" pulse at "h" equal in length to the time period
between the end pulses of these consecutive "true" end pulses.
This pulse at (h) is then gated through an And Gate with a 1000
Hz. clock and the resulting pulses at (i) represent the number
of 1000 Hz. pulses occuring during a R-R interval once every
256 times an hour. These pulses at (i) are accumulated by the
- 33 -
~$3~
Interval Counter" with output at (j). At the end of each
hour the contents of the "R-R Interval Counter" is compared
with the "R-R Control Value". This control value represents
the number of 1000 Hz. pulses that occur during a time period
that is 20~ less than a normal R-R interval for a given patient
(i.e., a time period corresponding to a R-R frequency 20%
faster than normal). This control value is set through the
previously mentioned externally accessible rotary switch 252
into "Memory Latch Control 2". If the hourly count is greater
than the control value then the "present Day R-R Status"
(which is normally a logic "one") is set to a logic "zero".
Once set to logic "zero", it remains at logic "zero" for the
remaining portion of the present day. At the end o~ the 2~th
hour this value i5 stored in the "previous Day R-R Status" for
use in making the present day's pump decisions at the beginning
of hours 1, 9, and 17. This output at (k) is a logic "zero" if
any hourly ~R interval count for the previous 24-hour day was
greater than the "R-R Control Value" for a given patient (i.e.,
if the average R-R frequency during any hour of the 24 hour day
was slower than the 20% greater than normal control value).
The two outputs at (g~ and (k) control the pump
operation. Normal operation causes the pump to dispense at all
even hours (Condition I in the Figure 17 Chart). Increase in
frequency for the lowest "hour frequency" for the 24 hour period
of the previous day (indicating need for more medication), a
logic "one" at (k), provides for the pump to dispense additional
doses at hours 1, 9, ~nd 17 (Condition II in the Figure 17 Chart).
These two operations occur in the following manner. If either
the output at (n) or (q) is a logic "one" then the input to the
"Pump Control" is ~ logic "one" at (r). A logic "one" pulse at
- 3~ -
3~4
(r) is the signal to turn on the pump. This signal at (r) is
a logic "one" at even hours ~output (m)), normally, and at
hours 1, 9, and 17 (output (p)) under Condition II of the -
Figure 17 Chart unless these conditions are altered by one of
the followiny restraints: If the output at (g) is a lo~ic "one"
for any hour then the output of the "Two Hour Memory'' at (1) is
set to a logic "zero" for the next two hours (normally this out-
put at (~) is a logic "one"). This signal (1) is gated with
the even hour pulse at (m) through an And Gate with output at
~n). If the output at (g) is a logic "one" for any hour then
the output of the "Eight Hour Memory" at (o) is set to a logic
"zero" for eight hours. (Normally this output at (o) is a
logic "one"). rrhis output at (o) is gatecl with the logic "one"
pulse at hours 1, 9, and 17 at (p) and the pulse at (k? through
an And Gate with output at (q).
With the foregoing in mind, it should be noted that
the power unit 210 of Figures 12-13 and which is associated with
the Figures 15-16 circuitry, is appropriately geared to operate
on a fifty minute hour in contrast to the 60 minute hour for
the logic circuit. This allows ten minutes between the end of
the power unit hour and the end of the logic system hour which
allows for any margin of timing error in the power unit move-
ment due to increased work load.
In summary, there has been described an implantable
system and method specifically useful for treating the human
and animal body in a unique way. rrhe l'power source" may take
ma~y forms. It may, be in the micro-power form referred to in
~,~ ~O"e ~e~ ~,~ ~ e~ c~S`.
my~p~G~ Patent 3,692,027 or in other equivalent miniaturized
forms providing a long life, i.e., measured at least in terms
of days and preferably years, source of electrical energy, for
energizing the system electronics and for providing power for
- 35 -
~.~3~
1 the drive member used to actuate the dispensing mechanism. The
apparatus lends itself to a wide variety of applications and
the medication may include pharmacologically active drugs needed,
body constituents, energy compounds, radioactive materials, and
the like.
It should also be noted that the term "body" and "animal
body" as used in the claims are intended to include animal, human
and other living bodies. Further, the term "body" is intended to
encompass any environmental body, whether living or otherwise
adapted to receiving a sel~, micro-powered and timed device for
incremental dispensing of substances into such body.
- 36 -
