U.S. patent number 3,923,060 [Application Number 05/463,262] was granted by the patent office on 1975-12-02 for apparatus and method for implanted self-powered medication dispensing having timing and evaluator means.
Invention is credited to Everett H. Ellinwood, Jr..
United States Patent |
3,923,060 |
Ellinwood, Jr. |
December 2, 1975 |
Apparatus and method for implanted self-powered medication
dispensing having timing and evaluator means
Abstract
An apparatus for dispensing drugs and other medications within
the body is adapted to be entirely implanted and to dispense such
substances over a long period of time, e.g., one to several years,
in accordance with the actual needs of the patient. A self-powered
dispensing device stores a single or plural substances in powdered,
liquid, or other dispensable form. Logic and self-timing means
control dispensing by monitoring single or plural sensors implanted
in the body and evaluating the sensed data in order to control both
the conditions under which and the kind of dispensing which takes
place.
Inventors: |
Ellinwood, Jr.; Everett H.
(Durham, NC) |
Family
ID: |
23839492 |
Appl.
No.: |
05/463,262 |
Filed: |
April 23, 1974 |
Current U.S.
Class: |
604/891.1;
128/DIG.1; 128/DIG.13 |
Current CPC
Class: |
A61B
5/021 (20130101); A61M 5/14244 (20130101); A61M
5/1723 (20130101); A61B 5/364 (20210101); A61B
5/14532 (20130101); A61M 5/14276 (20130101); A61N
1/36514 (20130101); Y10S 128/01 (20130101); A61M
2205/3507 (20130101); A61N 5/1001 (20130101); Y10S
128/13 (20130101) |
Current International
Class: |
A61B
5/00 (20060101); A61B 5/0468 (20060101); A61B
5/021 (20060101); A61B 5/0452 (20060101); A61M
5/172 (20060101); A61M 5/142 (20060101); A61M
5/168 (20060101); A61N 1/365 (20060101); A61N
5/10 (20060101); A61M 005/00 (); A61M 007/00 () |
Field of
Search: |
;128/260,2.6A,214F,218A,DIG.1,214E,DIG.13,213,2.08,2A,2R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Medbery; Aldrich F.
Attorney, Agent or Firm: Olive; B. B.
Claims
What is claimed is:
1. A self-contained and powered apparatus adapted to be totally
implanted within a selected animal body, including human, for
periodically evaluating selected internal physiological states of
such body and for periodically dispensing selected medication
therein according to such states while leaving the body ambulatory
at all times, comprising:
a. a unitary housing adapted to be completely implanted and secured
within and to the body at a selected site and having therein
various compartments enclosed by said housing and adapted for
mounting a medication storage member, a micro size power source,
miniaturized driving and dispensing means adapted to being powered
by such source for dispensing medication from such storage member,
miniaturized electrical data evaluation and timing circuit means
adapted to being powered by such source and to processing
physiological data including data obtained from sensor means
external of the housing to control the operation of said driving
and dispensing means and said housing being further adapted to
receive connections from external sensor means through the wall of
the housing;
b. a storage member mounted within the implanted housing and
adapted to store selected medication to be dispensed in selected
quantities;
c. a micro size power source mounted within the implanted housing
and secured proximate said storage member and having a useful
working life in terms of at least several days;
d. miniaturized electro-mechanical driving means mounted within the
implanted housing and adapted for being connected to and powered by
said source;
e. miniaturized dispensing means mounted within the implanted
housing and connected to receive said medication from said storage
member and adapted to be powered by said driving means at selected
times and being adapted when so powered to withdraw from said
storage member successive measured quantities of selected said
medication and to discharge such medication from the implanted
housing into said body;
f. sensing means selectively placed within said body externally of
the implanted housing and adapted to produce sensed signals
convertible to electrical data corresponding to a sensed condition
within said body;
g. connector means connected to said sensing means and passing
through the wall of said housing and adapted to transfer such
signals to the housing to be processed therein;
h. miniaturized electrical data evaluation and timing means mounted
within the implanted housing and connected to be energized by said
power source and comprising:
1. miniaturized electrical circuit means connected through said
connector means to said sensing means and adapted to receive
selected data from said sensing means and convert such data into an
electrically processable form and adapted for electrically
evaluating such sensed data at selected times; and
2. timing means operatively connected to said circuit means and
providing electrical time base information thereto whereby said
driving means is energized and actuates said dispensing means in
coordination with selected evaluations.
2. The method utilizing the apparatus of claim 1 of periodically
evaluating selected internal physiological states of an animal
body, including human, and of periodically dispensing medication
therein according to such needs while leaving the body ambulatory
at all times, comprising the steps:
a. implanting the housing of said apparatus in the body at a
selected site and with a store of selected medication;
b. implanting the sensing means of said appparatus at a selected
site external of said housing and within the same said body and
with said sensing means being connected through the said connector
means to the said circuit means of the said apparatus; and
c. allowing said sensing means to operate, to produce signals
corresponding to physiological states within the said body and
allowing said medication to be dispensed to a selected site within
the body on a schedule determined by said data evaluation and
timing means over a long period of time.
3. An apparatus as claimed in claim 1 including catheter means
placed within the body externally of the implanted housing
connected to receive and transfer the medication discharged by said
dispensing means to a selected treated site.
4. An apparatus as claimed in claim 1 wherein said drive means
constitutes a solenoid having an armature and said dispensing means
constitutes a solenoid armature operated dispenser.
5. An apparatus as claimed in claim 1 wherein said dispensing means
includes a reciprocable bellows for receiving internally thereof,
measuring and discharging said medication.
6. An apparatus as claimed in claim 1 wherein said storage member,
dispensing means, sensing means and data evaluation and timing
means are adapted for selectively dispensing plural sources of
medication.
7. An apparatus as claimed in claim 1 wherein said drive means
constitutes an electrical motor having a cam and said dispensing
means constitutes a cam operated dispensing means.
8. An apparatus as claimed in claim 1 wherein said storage member,
sensing means, dispensing means and evaluation and timing meansare
adapted to storing, sensing the need for and dispensing doses of
plural medications.
9. An apparatus as claimed in claim 8 wherein said dispensing means
is adapted to dispensing said doses of plural medications to
separate sites within said body.
10. An apparatus as claimed in claim 8 wherein said dispensing is
according to plural sensing schedules.
11. An apparatus as claimed in claim 1 including externally
available portal means adapted for replenishing medication in said
storage member.
12. An apparatus as claimed in claim 1 where said sensing means is
adapted to sense and develop electrical signals corresponding to
plural medical factors and said data evaluation and timing means is
adapted to electrically evaluate said factors and dispense said
medication according to such evaluation.
13. An apparatus as claimed in claim 1 wherein said sensing means
senses pressure within said body.
14. An apparatus as claimed in claim 1 wherein said sensing means
senses an electrical activity in said body.
15. An apparatus as claimed in claim 1 wherein said sensing means
senses a chemical activity in said body.
16. In an apparatus as claimed in claim 1 wherein said storage
member stores a single medication, said dispensing means comprises
plural dispensing means connected to a common said storage member
and said data and evaluation timing means is adapted to evaluate
the need for and to separately operate each said dispensing means
to cause said medication to be dispensed independently through one
or the other of said dispensing means.
17. In an apparatus as in claim 1 wherein said storage member,
sensing means, dispensing means, data evaluation and housing means
are adapted to sense the need for and to dispense a first
medication on a regular timed basis and a second medication on a
special basis.
18. An apparatus as claimed in claim 1 wherein said dispensing
means includes a discharge port and externally accessible portal
means enabling the entry of a suitable tool to clean said discharge
port.
19. An apparatus as claimed in claim 1 wherein said storage member,
sensing means, dispensing means and evaluation and timing means are
adapted to dispensing medication in a wide range of combinations of
single or plural doses, single or plural medications, single or
plural sensed conditions, single or plural sites, and under single
or plural timing schedules.
20. An apparatus as claimed in claim 1 adapted to dispense
medication for prevention of recurrent tachycardias and arrythmias
and wherein said sensing means comprise a cardiac type sensor and
said data evaluation and timing means includes an amplifying
circuit connected to said sensing means, a first QRS detector
circuit connected to said amplifier, a second QRS period analysis
and control value comparison circuit connected to said first QRS
detector circuit, an R--R interval analysis and control value
comparison circuit connected to said first QRS detector circuit and
said QRS period analysis circuit, an evaluating logic circuitry
connected to said second QRS period analysis and said R-R interval
analysis circuit, a timing circuit connected to time said second
QRS period circuit, said R--R interval analysis circuit and said
logic evaluation circuit and wherein said dispensing means is
controlled by said logic evaluation circuit.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to dispensing medical or physiological
substances or matter internally and more specifically to implanted
apparatus for dispensing these substances over a long period of
time according 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 my prior U.S. Pat.
No. 3,692,027 to which reference is made. So far as I am aware, my
prior U.S. Pat. No. 3,692,027 provides the first teaching of a
self-powered device which can be implanted and which is adapted to
dispense medical substances in pre-measured doses at specific
intervals over a long period of time. There has appeared in the
June 1973 issue of Fortune maagazine 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. The prior art
in the area of diffusion devices is also illustrated in U.S. Pat.
No. 3,379,996 by David Long and Moses Folkman for a polysiloxane
carrier for controlled release of drugs and other agents. The
device of this patent consists of 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 voltage 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 through the myocardial fibrous scar tissue by means of
iontophoresis. In these adaptations, the medication is in a
continuous diffusion state and is not presented in discrete doses
at timed intervals or according to the physiological needs.
Related to the present invention is the practice of implanting
devices which sense heart conditions by means of the cardiac
electrical activity and trigger electrical pulses to effect the
heart rate according to the sensed data. These devices have
generally been categorized 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 articles
listed below.
1. Goetz, R. H.; Goldstein, J. V.; Frater, R. W. M., Berkovits, B.
-- "Demand Pacemaking in Intermittant Heart-Block," Journal of the
American Medical Association, Vol. 10, pp. 657-662, 1968.
2. Nathan, D. A.; Center, S.; Wu, C.; Keller, W.; "An Implantable,
Synchronous Pacemaker for the Long Term Correction of Complete
Heart-Block." Circulation, Vol. XXVII, pp. 682-685, 1963.
3. Fischler, H.; Barr, I. M.; Auerback, Yerushalmi S.; Neufeld, H.
N. -- "Atrial-sychornized Demand Heart Pacing." IEEE Transactions
on Biomedical Engineering, Vol. BME-16, pp. 64-69.
A further area of the prior art related to the invention 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, pH
detection, ionic change detection, blood pressure or blood flow
detection, electrical activity detection, respiratory detection,
and gastrointestinal motility detection all constitute existing
practical types of sensing apparatus.
It should also be recognized that the prior art has shown that an
implanted device having a battery supply can be electrically
recharged without having to remove the device. Also, my own U.S.
Pat. No. 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
requirements 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 medication 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, suspension, or other dispensable form. The
decision making capability of the invention which functions on a
basis of changes in the sensed data, controls when the dispensing
apparatus operates and therefore controls the dispensing of
medication according to the specific needs of the patient at
specific times.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating the basic components of an
apparatus according to the invention.
FIG. 2 is a block diagram illustrating the application of the
invention to cardiac monitoring and medication.
FIG. 3 is a block diagram illustrating the application of the
invention to blood pressure monitoring and medication.
FIG. 4 is a block diagram illustrating application of the invention
to blood chemistry monitoring and medication.
FIG. 5 is a block diagram illustrating application of the invention
to dispensing medication to the same site from multiple
sources.
FIG. 6 is a block diagram illustrating application of the invention
to dispensing different medications to different sites.
FIG. 7 is a somewhat schematic and enlarged diagram of a minature
bellows pumping device useful in the invention.
FIG. 8 is a somewhat schematic enlarged view of a multiple bellows
type pump for dispensing the same medication to the same site but
in different quantities and under different conditions.
FIG. 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.
FIG. 10 is a somewhat schematic enlarged drawing of a bellows pump
with multiple separated chambers for different chambers or sites
having a common power source.
FIG. 11 is a somewhat schematic enlarged view of an implantable
system according to the invention and adapted to dispense different
medications from different sources under different controls.
FIG. 12 is a schematic diagram of the apparatus of the invention as
it might be used with superventricular tachycardias treated with
quinidine.
FIG. 13 is a schematic sectional view through the apparatus of FIG.
12.
FIGS. 14 and 14A schematically illustrate a portal arrangement for
replenishing medication to the system.
FIG. 15 is a block diagram of the decision making circuitry.
FIG. 16 is a more detailed circuit diagram corresponding to FIG.
15.
FIG. 17 is a representative timing diagram for dispensing plural
doses of medication.
BACKGROUND FOR LATER DESCRIPTION OF THE PREFERRED EMBODIMENTS
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 of biological signals that
relate to abnormal processes or variations in normal processes in
the body that may be used to evaluate the need for release of the
given medication, hormone, or other type of chemical into the body
or into specific organ or target sites. The dispensation of
medication 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 target site without systemic side effects developing.
In addition, the concept of feedback evaluation controlling or
altered release of medication will allow for an intermittent
dispensing of the drug which might handle a problem at much lower
doses than if medication is given over a sustained period without
sensitive regard for therapeutic needs and the possible development
of various toxic and tolerant effects. For example, an application
that will be described later is that of transducing a pressure
change in the blood vessels to provide information to the decision
making capacity of logic and timing circuits in the device which
activate a self-powered pump, to release a given quantity of a
blood 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 operation offers the
opportunity to help overcome some of the undesirable effects from
drugs such as adrenergic blocking agents, which when given
chronically produce untoward side effects, including psychological
depression and orthostatic hypotension. The same is true with a
variety 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 for
medication by the logic system of the invention.
Involved in the biological sensing for blood pressure or other
physiological changes that the device is evaluating, are possible
training of physiological responses, effects or behavioral
modification effects, by means of appropriate programming of such a
device with small logic circuits. The type of signal detected and
used for processing in the logic circuits may be either one signal
or a combination of bio-signals, one or several being necessary for
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
by a micro strain gauge attached to the diaphram, a strain gauge
attached to the stomach or in the upper duodenum to measure
gastro-intestinal motility and the type of motility, and a pressure
transducer to measure the increase in biliary duct pressure, and
use the combination of these signals to detect the injection of a
narcotic; the dispensing pump may then release a narcotic
antagonist and/or, for behavioral training, may release a drug that
would cause nausea and vomiting, thus providing for behavioral
modification or avoidance conditioning.
The types of application uses with evaluation of biological 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
electroencephalogram and electrocardiogram, special logic circuits
may be devised according to the invention on a minature basis to
provide for analysis of 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 invention 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 of 80%. The newer
anti-hypertension drugs have been more effective than this. What
this invention provides is a method for treating malignant
hypertension that is based on sensors inside the body and
medication pumped to various effector sites. The sensors may
include 1) blood pressure detecting devices in the 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 electrocardiogram. Blood
measurements allow the mechanism of the invention to differentiate,
for example, between the dystolic and systolic ratios. Combinations
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 effector side, the physician is given a wide choice with the
present invention of attacking the problem of malignant
hypertension in several sites: 1) the sympathetic outflow can be
blocked with ganglionic blockers; 2) the adrenal outflow or
releasing mechanisms can be blocked with ganglionic blockers; 3)
appropriate drugs are available which can be dispensed
systematically to block the adrenergic receptors throughout the
body; and 4) another group of drugs known as the varatrum 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)
systematic sites via intraperitoneal dispensation. Using four
sensors and two effector sites it is now possible to set up an
array contingencies, only some of which will be described. For
example, if the dystolic blood pressure increased beyond a certain
point, the systemic circulation, actually a site in the
interperitoneal cavity, may receive a dose of beta adrenergic
blocker antihypertensive medication; in addition, by means of
carefully monitored release of drugs to the sympathetic outflow via
a catheter, it is now possible to increase the effectiveness of the
antihypertensive drugs by blocking this outflow. As discussed
previously, this local application could help to prevent many of
the serious side effects of systemic ganglionic blocking
medication. Problems in hypotension 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 individual, for example, in
persons who have a heavy exercise load, the logic mechanism of the
invention may be established to respond only after 2 to 3 or even 4
hours of increased dystolic pressure thus allowing for extended
periods of exercise with slightly increased pressures. Combinations
of the devices shown in the drawings may be used to supply drugs at
the various effector sites.
In one specific adaptation a blood pressure sensor picks up both
the systolic and dystolic 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
micro-miniature logic systems in which several decisions are
made:
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 6 times a day, or alternately, it could operate twelve
times a day, thus medication decisions could be made every 2 or 4
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 released into the systemic
system.
3. Is the blood pressure above criteria more than 90% of the time?
We would 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 durg, a ganglionic blocking agent directly
to the sympathetic outflow in the sacral region and the first five
of the thoracic lumbar outflow.
The self-powered dispensing device of the invention allows for two
major changes in the treatment of hypertension: 1) It allows for
dispensing of the drug to a selective site inside the body, thus
reducing many of the side effects of more potent and hypertensive
drugs. 2) It allows for a much more careful titration of the
hypertensive effects 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 treatment of severe
hypertension. Currently the drug most often used in the treatment
of severe hypertension is guanethidine, which is a long-acting drug
that tends to accumulate in tissues and is excreted slowly. Leaving
off a dose of this medication would not have a major effect for
several hours, thus the potent side effects could continue for a
considerable period 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, however, be titrated in the
self-powered dispensing device of the invention. In addition, other
drugs similar to this compound, for example Bethanidine,
(1-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 dispense
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
results in vasodilation and improved peripheral blood flow of
vascular beds and a fall in blood pressure. Part of the potency of
these drugs is related to the low ratio of preganglionic axons to
post-ganglionic axons. Thus, ganglionic block has a very potent
effect. The 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 selectively block blood
vessels in large muscle of the extremities without major effects on
the gastrointestinal tract, genitourinary 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 bellow bags, later
described, may be used for this purpose. In other applications, the
radio-activity of certain radio-active anticancer 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 according to the invention
and the antrium of the stomach may be bathed in an anti-cholinergic
drug. Another use may be to bathe painful spinal dorsal nerves with
medication in nerve injury triggered externally by the patient but
with the availability still controlled by the invention's timing
and logic circuits to prevent overdose. In this case, the patient's
capacity to perceive pain would become 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 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 triggering 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 after years of careful
experimentation.
In the case of certain spastic vascular disease such as Berger's or
Raynand's disease, it now appears feasible with the present
invention to accomplish a periodic lumbar or cervical sympathetic
block with medication applied to this area. Medication may be
applied to the artery itself by implanting the outflow at the time
of vascular surgery. Medication would be dispensed dependent on
blood flow sensing.
Congestive cardiac failure may be detected with sensors that pick
up venous pressure and cardiac electrical activity, and controlled
with digoxin 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 conditions, especially
cardiac arthythmias, that may be treated by dispensing 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 supraventricular
tachycardia condition based on the electrophysiological activity of
the heart. This example is later disclosed to demonstrate the
present application of the concepts described above in a specific
device whose operation can be fully documented.
In summary, many potential applications present themselves
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 recognized as practical and
useful. Those skilled in the art will recognize 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 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 detailed application will be
presented.
FIG. 1 illustrates in block and schematic diagram form the basic
components of an implantable system according to the invention. In
particular, there is provided a micro-power source 28, a medication
storage 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 provided by a
suitable micro-power source 28 such as described in U.S. Pat. No.
3,692,027. The purpose of the sensor 30 in each instance is to
sense some type physiological, chemical, electrical, or other
condition in the body at 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 operate in a
manner to cause the dispenser 32 to either remain off or to be
operated to dispense some predetermined amount of medication from
the storage 29 according to the patient's needs.
Referring next to FIG. 2, there is schematically illustrated a more
specific and somewhat more complex application of the invention to
cardiac monitoring and medication. The micro-power source, while
not shown for simplification, should be treated as part of the FIG.
2-6 systems. In the application of FIG. 2, there is provided
medication storage 40 and an electric potential sensor 41, such as
employed in electroencephalogram 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, although a
more complete circuit disclosure will be provided in one example to
be presented later.
With further reference to FIG. 2, it is known that sensed electric
potential data such as obtained in electroencephalogram and
electrocardiogram examinations will reveal a plurality of factors.
The assumption on which FIG. 2 is based is that there are three
factors 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" output accordingly. Subsidiary circuits 44 and 45
can be designed for similar functions 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 47. Other combinations are possible. All of the
components except the sensor shown in FIG. 2 should be noted as
being enclosed in a suitable implantable housing 48.
To illustrate a further application, reference is made to FIG. 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 FIG. 4 a chemical monitoring system is illustrated. In this
embodiment a suitable chemical level sensor 60 is employed and
which, for example, may sense pH changes, ionic changes, glucose
level or other body chemistry factors susceptible to sensing. The
sensor 60 is connected to an appropriate 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 implantable housing indicated by 63 which
also houses the storage 59. In this application, the logic circuit
61 determines whether the sensed chemical factor 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 FIG. 5, there is shown in block diagram
form an application of the invention wherein dosages of the same
medication may be dispensed from different 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 from a common medication
storage 66 through a dispensing means 67 or a separate dispensing
means 68. For example, dispensing means 67 may constitute a low
volume, regularly dispensed medication whereas dispensing means 68
may be used for supplementary medication at the same treated
site.
In FIG. 6, the sensor 70 is connected to the appropriate logic
circuit 71 which controls a dispensing mechanism 72 for dispensing
from a drug storage 73 having, for example, a 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 medications can be dispensed to the
same or different treated sites with one medication being for one
purpose and another medication being for another purpose. Housing
76 encloses the apparatus.
From the foregoing description, it can be seen that the various
applications of the invention will each require appropriate timing
and sensing devices, appropriate circuitry for evaluating and
making decisions about the sensed data, and appropriate 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 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 of 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 data,
chemical data, electrical data, et cetera, and producing an output
depending on the data evaluation. In some instances, as previously
noted in connection with FIG. 2 there may be a plurality of output
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 FIG. 2. Miniature logic circuits of the kind required by the
present invention may be found in both in design books as well as
inn medical literature, e.g., designs for demand pacemakers. Those
skilled in the art will also readily appreciate the fact that the
present invention is of such wide scope that the logic circuit
designer is given a wide choice in the types of circuitry which may
be used to perform the logic functions.
Another important consideration concerns the implantability 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, the 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 invention is also well known. The long
term discharge of medication internally through 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 kind encountered in prior
practices 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 storing a
treating substance under pressure in powdered, liquid, or other
dispensable form, means for pumping or otherwise removing
predetermined portions from such storage and means for directing
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 most immediately available device suited to the invention for
storing and dispensing medication is illustrated in my prior U.S.
Pat. No. 3,692,027. For example, such a device as shown in my prior
patent may constitute the dispenser 32 illustrated in FIG. 1 and
the dispenser control 31 in FIG. 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 FIG. 1 senses the particular condition at timed
intervals and the dispenser control 31 of FIG. 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 of dispensing
mechanisms. Mention has already been made of the mechanism
described in my prior U.S. Pat. No. 3,692,027. Another mechanism
for pumping fluid medication is shown in FIG. 7. In FIG. 7 there is
shown in a highly enlarged form a housing 80 mounting a piston 81
secured to a bellows container 82 made of polyvinyl or other
suitable material. A rod 83 attaches to piston 81 and is caused to
move inwardly by an appropriate solenoid 84 and to move outwardly
by an appropriate spring 85 acting against a head portion 86 as
schematically represented in FIG. 7. Solenoid 84 is, of course,
controlled by an appropriate logic control as previously explained.
The bellows 82 receives medication through an inlet tube 87 and a
one-way valve 88 and discharges such medication through a one-way
valve 89 and a discharge tube 90. It should, of course, be
understood that the pump structure shown in FIG. 7 will 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 common to many types of physical disabilities 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. FIG. 8 schematically
represents a device suited to this requirement. In particular, cam
100 is driven by a suitable micro power motor such as shown in my
prior U.S. Pat. No. 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
causes the bellows 104 to discharge from the drug storage area 105
a predetermined dosage previously obtained from a drug storage 106.
As cam 100 rotates and after discharge bellows 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 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 FIG. 9 there is indicated an arrangement for discharging two
different types of medication. In FIG. 9, cam 120 and solenoid 121
should be considered similar in their operation to the cam and
solenoid operations previously explained in connection with FIG. 8.
In the FIG. 9 application, the cam 120 operates on the bellows 123
and solenoid 121 operates on the bellows 124. In the FIG. 9, as
well as in the FIGS. 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 of 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 through not
shown or specifically explained.
In FIG. 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 FIG. 9, provides
for dispensing two or more types of medication to two or more body
sites. The FIG. 9 arrangement allows such medication to be
dispensed to two sites at different pressures using two power
sources whereas the FIG. 10 arrangement 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
FIG. 10 provides for a two or more drug dispensing capability
without the greatly increased friction of more cylinders and
pistons. The bellows chamber in addition to its sealing functions
allows for a vairety of options at the time of implanting surgery
simply by substituting various bellow configurations in the pump.
This means that the surgical facility does not have to maintain
many types of more expensive total pump configural changes. It is
anticipated that a large variety of bellow shapes and sizes will be
found useful and which can be substituted in the pump cylinder for
a multitude of treatment purposes.
In FIG. 11 there is schematically shown a system of a type which
corresponds with the type of application diagram in FIG. 6. Here
again it should be understood that the schematic diagram in FIG. 11
would, in practice, correspond to a device of substantially less
physical size. In particular, there is represented in FIG. 11 a
housing 150 having appropriate suture anchors 151. Within the
housing 150 there is provided an appropriate compartment 152 for
holding some predetermined amount of medication intended to be
released over a 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
circuitry 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 timed medication a micro-powered unit 160 of the type shown in
my prior U.S. Pat. No. 3,692,027 is controlled by the circuitry in
compartment 154 and when indicated by evaluation of information
coming from sensor 155, unit 160 turns on and rotates the cam 161
thus driving the cam peaks against roller 180 attached to the shaft
of piston 162 so as to discharge the medication confined in the
storage area 152 through an appropriate discharge tube 164. During
discharge the flap valve 170 closes as piston 162 moves to the
right in FIG. 11 and a sliding cylindrical valve member 171 moves
upwardly in FIG. 11 so as to allow communication between pipes 175
and 176. As cam 161 continues to turn roller 180 contines to ride
on cam 161 by reason of spring 181. Flap 170 opens, sliding valve
171 moves down and a new charge is stored in the storage area 163.
portals 158, 159 provide 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 FIG. 11 against the tension of spring 192. Flap valve 193
closes, sliding valve 194 rises as shown in FIG. 11 and pipes 196
and 197 are placed in communication to allow discharge through pipe
164. On the return stroke 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 medication 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
recurrences of artrial fibrilation and flutter as well as
supraventricular tachycaridas not due to digitalis toxicity.
Quinidine is also effectively used, as well as procainamide, in
prevention of recurrences of ventricular tachycardia. Quinidine is
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 of treatment of
cardiac arrythmias can be found in "Drugs used in the Treatment of
Cardiac Arrythmias" in Treatment of Heart Disease in the Adult, 2nd
Edition, Rubin, T. L.; Gross, H.; Arbeit, S. R., Lea and Febriger,
Philadelphia, pp. 297-324, 1972. One of the difficulties in using
these drugs 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 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 example is the supraventricular tachycardias. The
present example is directed to counterpointing the heart rate
against the toxic changes produced by quinidine, that is widening
of the QRS Complex (a component of the electrocardiogram). The dose
of quinidine can thus be monitored by use of the invention and
reduced when there is prolongation of the QRS complex which occurs
as the dose of quinidine begins to reach the threshold for toxic
effects.
FIGS. 12 and 13 demonstrate the basic construction and operation of
the device to be used with supraventricular tachycardias treated
with dispended quinidine. The pump motor 210 is of the type shown
in my U.S. Pat. No. 3,692,027 and 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 212. 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 2-hour dispensing schedule, that is dispensing
medication every two hours unless altered by decisions based on
evaluation of the sensors (the 2-hour schedule is accomplished by
turning off the pump motor 210 every other hour): 1. The mechanism
would dispense very two hours as an average dose timing. 2.
Depending on the feedback evaluation, it may suppress a dose of
medication for 2 hours thus leaving a 4 hour interval between doses
when this is indicated. 3. Extra doses can be 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 medicaion 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 manifest
themselves, then the mechanism may be cut off for sufficient time
to increase the interval between medications to four hours.
In actual practice with a supraventricular tachycardia, the
electrodes 250 shown in FIG. 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 the
catheter 248. An electronic logic recognition program provides for
identification of the QRS complex and another program subsequently
quantifies the ORS period and R-R interval as described in relation
to the chart shown in FIG. 17. Operationally, 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 20 percent, then the mechanism will provide three
extra 1 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 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 of the criteria provided for in the
first series of feedback options.
The chart depicted in FIG. 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 lowest frequency for the previous 24
hour day is compared with the control value to make this decision.
Then, if this 24 hour lowest hour frequency is 10-20% higher than
control, the logic 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 percent of contol value
and given a weight in the following schedule:
1. 110% or less than control value given weight of 0
2. 110-120% greater than control value given weight of 1
3. 120-130% greater than control value given weight of 2
4. 130-150% greater than control value given weight of 8
5. Greater than 150% of control value indicates ventricular
premature contraction and is given a variable weight of 8 or 16. If
over the hour, out of the 256 sampled QRS periods the weights add
up to 256 or greater, then the pump is turned off for the next even
hour operation and secondly stops the extra dose for that 8 -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 provided for at hour 9 would be deleted also.
Other aspects of FIGS. 12 and 13 that require explanation 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. Operation of the switch is
accomplished by turning the needle through one to eight of the
various positions. Contact to the switch function are through
contacts on the three triangular surfaces of 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 material.
Position No. 1 of the rotary switch provides for battery recharge
through the needle contacts. Position No. 2 provides for monitoring
the electrocardiogram from the implanted electrodes. Position No. 3
provides for stimulation through 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 Nos. 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 introduce a wire stylet if mechanical
block occurs in the catheter. (3) 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 FIGS. 14 and 14A. A hollow bore needle, not show, with
a round to square to round 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 open and closed
configuration. Pinion 302 is held in position by top plate 310. In
FIG. 14, the external casing of the device is represented by line
311.
For purposes of replenishing medication, the input portal 254 is
employed. Since the introduction of pressurized replenishing
medication has been previously discussed in my U.S. Pat. No.
3,692,027 and a suitable portal structure described, no further
detailed description of this operation or of the refill portal is
deemed necessary.
FIG. 13 shows in further detail the bypass system with the details
of the attachment of the catheter system to the pericardial sac.
O-rings 255 beneath the entry portal are provided for sealing
purposes. A one-way valve 256 in the catheter leading to the pump
provides for block of 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 uniform catheter section and an appended expanded
catheter section in the form of 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 embedded 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 FIG. 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 FIG. 15 is the "brain" of the system and
provides control to the "pump" based on the presence of conditions
I, II or III, as previously described. The type and nature of
components required for the FIG. 15 circuit are generally known and
have been elsewhere indicated. Therefore, since FIG. 16 represents
a more detailed description of FIG. 15, it is believed those
skilled in the art will readily understand the circuitry and
operation depicted in FIG. 15 after reading the description to
follow.
The description now turns to a description of FIG. 16 which
constitutes a logic flow chart suited to the application related to
FIGS. 12-15 and 17. Since the components in FIG. 16 are identified
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 of the circuitry of FIG. 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 of the
time period between two consecutive QRS-complex, i.e., R-R
interval.
The measurement of the time period of the QRS-complex is
accomplished through the "Percent Control-Time Classifier." The
signal at (b) is the signal to reset and then start this classifier
which classifies the time period of QRS-complex into one of five
time intervals: (I) 110% or less of control time, (II) 110% to 120%
of control time, (III) 120% to 130% of control time, (IV) 130% to
150% of control time, or (V) 150% or greater of control time. The
control time is the time period of a normal QRS-complex for the
given patient. The signal (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 of the
QRS-complex, this counter is incremented by 0, 1, 2, 4, 8, or 16
counts. Each classification adds a set number to the counter.
Classification (V) has the additional option of having its count
value changed to 4, 8, or 16 through "Memory Latch Control 1". This
memory latch control can be set through the previously mentioned
externally accessible rotary switch 252, not shown in FIG. 16 but
shown in FIGS. 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 "1 " otherwise (g) is a logic "0".
The measurement 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 1 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 "R-R 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 1) is set to a logic 0. Once set to logic 0, it remains at
logic 0 for the remaining portion of the present day. At the end of
the 24th hour this value is 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 0 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 FIG. 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 1 at (k), provides for the pump
to dispense additional doses at hours 1, 9, and 17 (Condition II in
the FIG. 17 chart). These two operations occur in the following
manner: If either the output at (n) or (q) is a logic 1 then the
input to the "Pump Control" is a logic 1 at (r). A logic 1 pulse at
(r) is the signal to turn on the pump. This signal at (r) is a
logic 1 at even hours (output (m) ), normally, and at hours 1, 9,
and 17 (output (p) ) under Condition II of the FIG. 17 Chart unless
these conditions are altered by one of the following restraints: If
the output at (g) is a logic 1 for any hour then the output of the
2 Hour Memory at (1) is set to a logic 0 for the next 2 hours
(normally this output at (1) is a logic 1). 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 1 for any hour then
the output of the "8 Hour Memory" at (o) is set to a logic 0 for 8
hours. (Normally this output at (o) is a logic 1.) This output (o)
is gated with the logic 1 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 FIGS. 12-13 and which is associated with the FIGS. 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 10 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 movement 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. The "power source" may take many forms. It may be
in the micro-power form referred to in my prior U.S. Pat. No.
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 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 self, micro powered and timed device for incremental
dispensing of substances into such body.
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