CA2210078A1

CA2210078A1 - Implantable medical device with enclosed physiological parameter sensors or telemetry link

Info

Publication number: CA2210078A1
Application number: CA002210078A
Authority: CA
Inventors: Paul J. Patrick; David Prutchi
Original assignee: Individual
Current assignee: Intermedics Inc
Priority date: 1995-02-22
Filing date: 1996-02-22
Publication date: 1996-08-29
Also published as: US5730125A; WO1996025978A1; JPH11500930A; EP0810895A1; US5556421A

Abstract

An implantable medical device (10), such as a cardiac pacer (12), defibrillator or drug delivery system, includes a container housing (14) the required power source (16) and circuitry and a header portion (20) molded or glued to the container housing. Sensors, including physiological parameter sensors (32, 34, 36) as may be necessary to control and implement the operation of the implantable device, or a telemetry link, or both, are disposed and sealed within the header (20). The header may include electromagnetic focusing devices to enhance the performance of the sensors. The sensors may include two pulse oximetry sensors that provide differential measurements to improve detection of arterial blood flow.

Description

W O 96/2S978 PCTrUS96102363 IMPLANTABLE M~ICAL DEVICE VVlTH EN
PHYSIOLOGICAL PAP~M~ER SENSORS
OR 117 ~ ~.l~RY LINK

Field of the Invention The present il.~lion relates generally to imp~ le medical devices, such as cardiac pacernalcers, defibrillators and any of a variety of drug delivery systems. More particularly, the h.~.,.llion relates to such i~l~-~t~ble l,e~enl devices in which tel~ ,tly tr~lc~ur,~rs or phy~;~logi--' parameter sensors are c~ çd and sealed within the header of the ....pla~lable device.
R~ d of the Invention ~ mrl~nt~l~le medical devices having electrical circuit ~l~ly.~ are well known in medical science. Some of the most c~.--.. ~n forms of such implantable devices are p;lcçm~lrrr.~ and defi~rill . ~A~it~ ly~imrlqntr~le drug delivery systems are available for s~plyhlg needed mPrlir~ion for lr~ of disease or for r~ondillg to the physiological dçn~ of a patient in an e.~ i.. n A pacemalcer (or "pacer" as it is c~ ly labelled) is an impl~ntable medical device which delivers ele~ pulses to an electrode that is impl~nted a~lj5CÇ-~I the patient's heart in order to stiml~l the heart so that it will beat at a desired rate. A normal human heart contains a natural p ~ b~r by which rhythmic electrical e~rcit~ion is developed. If the body's paçem~1 rr pe.rv~ s co~r~lly~ blood is o~ ,..dled in the lungs and effiriently pumped by the heart to the body's oxygen~ dil~ tissues. However, when the body's natural pac~mqt-~r ..-~'r..~ l;olls, due to age or dise. se, an implantable p~ r often is r~ui.~d to prol)e~ly stiml~lqte the heart. An in-depth ~ rl~n~~ion of certain cardiac physiology and p.~ r theory of operation is provided in U.S.
Patent No. 4,830,006.
In recent years, "rate~ ol~h~e" p~ rf- ~ have been developed which, in response to a sensed physiological ~ ., will aulv-~ r~lly change the rate at which the par~mql~or provides stim~ ing pulses to the heart. The physiologir-ql pala~ provides some inrlir~tion of whether the heart rate should i,.~.case or decrease, as dictated by the physiologir-q-l needs of the patient. For e-rmrle, where the patient is at rest, the rate-.~spo~sive p~ 5t-e~ will ~ a normal or base rate of, for eY~mrle, 60 70 pulses per minute. However, if the sensed physiological parameter i~lir~~s that the patient is exercising, then there is a need for the heart to beat much faster, and the pa~mqlrer will respond by stiln~ ing the heart to beat at a higher rate, ~vr e~cample, 100-110 beats per minute.

W 096/25978 PCTrUS96/02363 Similarly, implantable defibrillators sense physiological p=~ ,. . in order to d~ ...;.-P
when to supply a ~IPfihrill~~i~ shoclc to a patient's heart. Ventricular fihrill- on is a co~
Ud~ eil byrapid,c_aoticelP~ 1and~ p"~ activityoftheheart'se-rit~l-lemyocardial tissue, and results in an i~ P~ cessation of blood flow from the heart due to the S uncoo~i~ or; P~ v~1 action of ~e ~ c Defihri~ ion is a terh~ ue employed to t~ ~ fihrill by applying one or more high energy electrical pulses to the heart in an effort to overwhelm the chaotic ~ t~ io~c of ihldividual tissue sections and to restore the s~ roi.
c~ ll..clioll of the total mass of tissue.
Lilcewise, ;..~ ;hle drug delivery systems also may rely upon phy~;ologir~l p~
sensors to provide signals that may be pr~c~s~d intPrr~lly in order to ~ r when, and in what amount, a stored drug is to be delivered into the patient's body. In the ~ of cerhin ~i~P~CP~, it is desirable to r 1~ ,. a drug into a particular location within the hody where the drug will be most errf~li~ f in combating the loc~li7PA disease. As another example, in treating cardiac allLylll.llias, it is sometimes desirable to deliver the drug directly to the heart. In other applic~tio~ of ~ "1 ' le drug delivery systems, the location at which the drug is introduced into the body is not critical, and the body's circulatory system is relied on to carry the ~
drug to all parts of the body. Drugs that may err~li~,fly be a-~ ,r~ by imrl~-lt~hle delivery systems include insulin, gluc~se~ heparin or any of a variety of ch~----)ll~e. ~lic agents.
Rer~ -- e the con~ r~uili-lg the use of an imrl~--t~hle device may drastically impair the patient's quality of life or, in some ;-- l;~ -rf c, is a life Ihr~ g con~lition~ having reliable in-lir~~or~ of phy~;ologir~l ~ is imperative. Physiologir~l p~aul~ te; sensors and activity p~..ete. sensors that have been employed in association with ;...~ le devices, or that those in the art have ~.gg~ted may be employed, include those that sense respiration rate, blood oxygen saturation level, le~i)~.du-e, blood p~ ,u.e, pH, length of the Q-T interval, the length of the P-R
interval, ~ J.acic i~-~pe~ ~ ~ e changes, nerve activity, biorhF~mir~l concc-~ lions (such as e.~y and glucose) and motion or acceleration.
Regardless of the sensed parameter, most prior art imrl~nt~le devices have relied upon phys;ologi ' parameter sensors that are po :~;n~ ..lvlt;ly from the impl~nt~ le device. For example, U.S. Patent No. 4,886,064 d;~clo3P-s sensors that are imrl~t-F~d re."olely from a ~a -' and that wil~l~ssly lla.-s---il to the ~a~ ~' signals that indicate or correlate to a sensed p~uall~t~. In many other prior art implantable devices, however, the remote sensors are i. ter~l-n-F-~d with the implantable device by means of electrical leads or cQn~ tors that are enca~sed in a catheter that e~ctends between the remote sensor and the imrl ble device. For example, U.S. Patent No. 4,903,701 di~ )SF ~ an oxygen sensor that is located re~ ely from the pacemal~er and that is .~ Pd on the F~lF~ n ;~ ~ 1 leads used to I ~ ~ the g~ 'ed pulse from the ~ ' to the s '- _ electrode. U.S. Pstent No. 4,763,655 ~1;Q~1O--- a If,.~c.d~u-~e sensor snd a blood o~cygen sensor that sre inlpl~ ~tPd r~lel~ from the rac ~ housing. The sensors are coupled with the pace aker cir,_uiLIy by conductors encased in a catheter.
Designs for ~- ' 'e devices that rely upon remote sensors pose ~v ~~ problems.
S First, ,~lh,rl~qucncy transmission, as s~ d by U.S. Patent No. 4,886, 064, typically requires t r~ ~tPrS and r~;~ that s~l,s~ ly ill~ ledse the volume, weight snd compl ~, of the pa~~ .r and sensor. These c~ v~ ;rc are generally ~Jn~ ir~lble in an ;",pl~ ~1 '.le device where, for patient comfort, small size and light weight r~- L .~,j,f ~ are desired goals. Second, remote sensors often need specialized catheters and are ~ --c~lt;l,le to fLsation and migr~inn proble_s.
Another ~ of e , l~,/ing r~ cly-po~ d S~n~ors~ at least those that are imr~
within or adj~ to the patient's heart, is that should such a sensor fail, delicate surgical lion may be required to remove and replace the faulty sensor. By contrast, pac~ and many other imrl~hle devices are typically pos;~ io~ in an easily ~c~:ble location just beneath the patient's s~in, and can be ~c~ed and replaced without the risk of life-llllc t~ ~ g or c~hu~lldy costly surgery. Also of ~ignific~~ç, because of the r~uh d electrical co~ ecl;ons between the remote sensors and the internal ~ ;uil~ ~I within ~he implantable deviçej the deviçe is s~ r~
to infiltration by corrusi~ body fluids. Any such infiltration will almost i..~ Iy disable the el~rici~l Ci~uil~y in the device. Thus, the locations at which the sensor's leads pe~lella~d the housing of the in~rl~t. I le device must be sealed to prevent infiltration of body fluids.
Those involved in the medical arts already have conr u-lldd the problem of pre~ g fluid from h.r.lL...Iing into an imrl ' 'e device at the loc~~i-m~ where external leads attach to the device housing. As m~ntion~d previously, it is co.~ ional practice to surgically implant a stim~ ting elec~rode ~ e-~l the heart and to hllercolm~;l the electrode to the p~ - via con~ tin~ leads.
This .u~ ge.ll~l~l is shown, for example, in U.S. Patent No. 4,903,701. Additionally, certain implantable m~ir~tion delivery systems require that electrical con~ ctors hllercomlect an imrl -lt~~)le device c4 ~ h ~E a power source and control cin uil-y and a remotely positioned drug g device as, for e~ample, ~iicclose~ in U.S. Patent No. 5,041,107. It is, of course, ~.~.l that all suc~ leads be sc~ ,ly ~tr~hf~d to the imrlAAntrl~le device to prevent the leads from becc".,i-~~ h-a~l~e l~ llly decouplKI At the same time, because pa~ ers and drug delivery systems require periodic repl~~Pm~nt and because this repl-c~ 1 procedure ideally is r ~ u ~r~ ~ -d without di;-lu-l,i~ any remotely imrl~nt~ electrode or other device, the CQ~ ion~
bch. ~n the leads and the impl~nt~hle device housing must be readily ~ -c~ u~ U~')le. It is critical, of course, that the lead If~ n and ~ r h~ prevent infiltration of any fluids into the imrl ' 'e device.

W 096/25978 PCT~US96~02363 To date, it has been co~ n in the design of imrlqn~ le devices to provide the device with a header portion which inr~ es one or more t~nnin 'c for landing and ~ g any e~cternal leads. The header, which may be made of an epoxy material, su~ b and ine~ s the ~ -tA~ Intemal cQn-lu~to- ~ reù~e~,~ the 1~ ". ~1 in the header portion with the elertric~' S e.~.,.~;ll~ c - ~ -' within the housing of the implantable device. F.Pmpl~ of such headers are shown in U.S. Patent No. 5,282,841 and 4,072,154. Where ph~ ~logical p~ ~r sensors (rather than electrodes) are ;.~ remotely from the in~rlqnti~-le device, similar such termination means must be provided for landing and ~ -.--;-- ~~;-~g the con~ or~ that signals between these remote sensors and the implantable device.
In part due to the various problems and disaJ~ , - of poC I;o.-; n~ sensors r.i : ly from the pacemalcer or drug delivery device with which they are q~coci~ it has been suggested that he sensors be housed within the impl~~~t~hle ~ .e.ll device itself. For e~mrle, U.S. Patent No.
5,040,533 pr~)oses an ih~ ~le carlio~aucular llcdl~ device having self-co.l~i..ed sensors and a window formed in the wall of the co-~ to permit the sensors that are housed within the cc~ ;-- to detect or measure a ph~i,iological p~ through the window. Although pruposed as a solvtion to some of the aru~ ;nn~d problems ~or~ ~ with external sensors, the "windu .. ~" p a- -' pr~_~b ~itinn~l and even more p.u..vu..ccd sealing problems. Because the ;.-l~ ri~~e between the window and the walls of the cc ,l~hltr must prevent infiltration by body fluids, a complete and ~nllUling seal must be devised and installed along the entire pc~i--.~ter of the window. Providing such a seal in the walls of the co~ .;.. pr~ si~nifi~qnt .. -- ~--r~ i"g ~lifflrllltiPS e,cpe~ y cQnC;~pring lthe small size of the c~ P~ that is typically employed in pa~ . Further, the additional coll,l~ol1c.lb and ..- ~fi r~ h.g time and effort that are needed to provide such a sealed window in the walls of the imrlq~tqhle device would increase s ~ ly the cost of ma.~ ~r; I~ g such a device.
Thus, despite ci~ifirq~t a~lv~ces in the art that have been made over the years, there remains a need for an imrl~ ~t~ l le device capable of housing and pl~ lg any of a variety of types of physiol~gir~l parameter sensors. The device must permit the sensors to carry out their ~ Pn~Pd r - l;.u-c and, ~ PQIlsly, must seal the devices from e.~,û;,uie to coirosive body fluids. T~s~ e---'ly well rece;ved would be an imrlqnti~l le device that would be no larger than those prt Iy employed and that would not require cignifi~qrlt ~~ hionql retooling in order to ... ~ ..,r ~... e a new and spe~i~li7ed housing, such as one r~uiling th$ a window be formed in what would otherwise be a cc~ u~ wall. Ideally, the new device would not create ~ itionql sealing problems and could employ Icnown and reliable electrical power surplipc and cil-,uilly. P~-,f~.al)ly, the inlrl ''e device would also house atcl~_h~ linkthrough which data and instructions could be com~ Pd to and from the il~~ ti~le device.

,~i.~. 1 '-* -17~ .U'I ~-~ICA 02210078 1997-07-10 r~ c~ l~c~ct~ ~b P. ~, SumnL lYofthe ~ven~
In a~Or~l~t ~inth ~e present ~v~o~, ~cre is proridcd an ~ hle me~ical t~e hav~ng a con~iner for housmg electrical ci~ui~ ar~d a hca~ closes ~nd sesls ~e Co~ . One or ~or~ ;arS, whlch m~y 10e physiological ~ t~ 1 scnsors ~r t~ or bo~, :~re 5 ~tamed and seal~d ui1~ e h~ad~.
Ihcc~ s;Li~ ofthe heu~is, ~ ~,~ ~ ~e p~c~ ~ ~m~
Ihat is, ~Le makr.al ~m w}~ich the head:r is foImed must allow ~e sensor to ~tcct or measu~:
tl~ough th~ head~ d phys~o1o~Oical ~,~.. t~ XF~ hepR~ r ~ or,the in~n~c~ m~y ~cludeah~d~ fonnedof¢pa~y,pi~c,g~s~ ~ cdc. Ihe ~ on a~o m~y 10 ~nclude ~ Qln~n~ g ~c~ces ~.at ~ fonmel ~2 ~ a~l~d ~ ~Chc~to ~hance s~ e~ ~>1) "~n~
~ k~ x~ ~e desi~d ~]i~Li~lf~ei~l~blode~cc,thc~2ven~cn m~y ~cl~
any of a Yarie~ of s~nso}s ~at a~e pre~n~ a~ ble ~r ~at ma3r ~euo~c a~labl~ for de~Rc~g ~r l~c~ ;ng re}e~ t ~ ~ ccrtai~ ~ c, sach se;ls~xs may include 1 s pl~u~ or phatodet~ctors. 1~ one par~cular t.lll~lhll~.Lt of the ~~ , such phot~.~LLt~
andd~c~rs~ a~a~gedtoc~npn~ an ox~n~y ~5~ fi~ dC~ blood oxy~ t~
p~r~c~ly ad~an~ sfnnm of ~ ~tion c~loys ~YO v~ hy ~ 2t ~ ~oS;~n~d . wi~in the header so ~ s~~ c ~ ce sn d~ ent dise~tions. T~ r .... l ~eL~ ~a~ sign~ ch ~n~ ~ ph~c~d ~ ~ w~y ~ el;mm8te t~e ~5 '~ ;v~ e~ at 20 ~ G~wlL m~y have o~ ~e abilisy af a single o~e~y ~ns~ to make ~ d~i~ ~ouieln~ L of oxyg~ns~ of~.~*~l~YL~edv~ ~l~odfl~ ~ c..lhoA~ of~e...~lL~ t ~ploy such ph.~tk~ k~ e~rlven~on will ~'.ude a u~ c~ or L~ L header, ~r e~nple a head~r made ~ ~ ~aterial ~t is t~ m ~e i~ red 3nd .~3 pu~tions of ~c oFt~ L~
In anot~ ba~t;~ t ~f ~ headcr ~clud~ scn~ t a~e c~cii.. ~ or resisti~ely co~led to the fl~id and ~ssue ou~ide ~e hous~ng Such se~so~s ~nclude a c~.~ cli ,c plax d3sp0~d 1~ the he~ edc~ d~s~ncc fi~m ~e ouk~ su1~c~ of the h~ en ~hG~
of ~e iu~e~lioil mcll~d~ r~ Iy coupled S~57 the l}eatCr may be f~;~ of a m~riaL ha~g le~-ui~ t and l~ lume resis~ as? f~¢ a~rnpie, a didec~ic c~nstant of ;.g 3~ ~nd ~ ~lu~c ..,~ IOI2 ~h~n. Whese ~e scnsors ar~ ,Li~ c~ie~, selccted p~rtions of ~.e hc~d~ may haY~ a Law volume ~esis~v~ty of ~css tha~ 1 .~ lO~ ohm~.
Y;-llh~uL ~ hc Ly~u uf sens~r, thc invcntio~ m~y be 1~ ~r~
defi~nill~tn~ or ~ am$ dc~ery 5y~. ~ these ,~ Ar~ c ~eYices, t}~C il.~_..Li~
mcludes ~ ~ ~.~'~on C~Ultt~ Ye sign~s ~ ~c ~ ~at ~ ;u~co~7~ of ~e ~~SOE~ S~

W 096125978 PCTrUS96/02363 measured physiolcgical p~-et~". The i,l~e.~tioll further jnr~ p~ within the c~,~ a control circuit, such as a lui~foprocessor, and an output circuit. The output from the sensor t:~du~lion circuit is r~e;~od by the control circuit which, in accor~allce with a preJd~e ...i~ed algorithm, will signal the output circuit, such as a pulse generator, to ge~ 'e an e1e~. ic~l pulse of a du~a~ion and ~agr~ le .~uih~d for p~,.ly s~ the heart or d;~ an 3~ dose of m~irP~inn The present i~ havi~g self~ ' seosors e~ the risky or d~.~,_rous surgical intervention tbat may olhe. wise be r~ui~d to remove remotely pos;~ inllod sensors which fail. Further, because the i ~e.llion talces a~lv l~ of a header such as that typically employed in present day pacemalcers, the tried-and-true arrangement used in sealing co.. ~.,.. liollal pacemakers may also be used when impl: g the present invention. Likewise, no ~rfY~ i7f~d housing or C~ f,- for the implantable device ~ iuil .y is ~~ui,.,d when practicing the invention. Instead, lional coll.pone.lts and " ""~jrl"~i,.g tprhniql~ps may be em~ )yed, and no additional i..t~,.L-~s are created which require comrli~ ~ d or costly seal designs.
Acco~i.. ~;ly, the present invention co".~ .cs a ~lllI,hl~ion of features and ~Iv~~,_~
which enable it to s ~ -~ly advance the t~hn~logy associated with imr!~nt~l le medical u~ l devices. The r~ .nl~ lics and advantages of the present i..~.llion described above, as well as "'~ ti~ features and benefits, will be readily ~,pale.ll to those slcilled in the art upon reading the following detailed d~ i~lion and r~,f~ i~ to the aGco.~ ing d-~
~riefr~riution of the D. ~
For a detailed description of the pl~f~ d embo~3im~o-nt~ of the h.~ ioll, fer~.~,..ce will now be made to the ..~c~ i-.g dl....i-.~;. wherein:
Figure 1 is an elevational view of a p~ made in accordallce with the present il~ io~l.

Flgure 2 is a 5~ l;c block diagram of the pacc~ ' P~ shown in Figure 1.

Flgure 3 is a s~ h' -~ ' block diagram of another embodiment of the present i..ve..~ion employing an OA;III~ sensor embedded within the header of the pacer shown in Figure 1.

Fgure 4 is a partial elevation view ;,h~. .. iug another ~ ;ve embodiment of the present Flgure S is a s~l;- n~ view taken along line 5-5 in Figure 4.

W 096/2S978 PCT~US96/02363 Figure C is a partial elevatio l view sh~wing another ~ five embodiment of the present ~Ul~ iOLI.

~ iSgure 7 is a se~ ' view talcen along line 7-7 in Figure 6.
S
Figure 8 is a partial ~ ' view of still another . ' ~ ~ e, embodiment of the present i..~e~t;on having an o~cimetry sensor emt edd~Pd within the header of an imjpl ~ -trt le device.

Figure 9 is a top view of the implantable device shown in Figure 8.
Figur~e 10 is a 5~ ic blocl~ diagram sh~ g another ~ 'iv~ embodiment of the present h.~. - having cQ~ .clivè plates embedded within the header of an itnrl~ntr' le device.

Flgure 11 is a ~' -~ diagram sh~wing the e.~uiv ' circuit co..~-lding to a portion of the circuit shown in Figure 10.

F~gure 12 is an elevdlional view of another all~.uali~,e embodiment of the present invention as employed in an i-mpl~n~~~le iont~phol~lic drug delivery system.

~Sgure 13 is an elevational view of another ~llv .- ~ iv-e embodiment of the present hlvelllion cllllJloyèd in another type of imrl~nt~l-le drug delivery system.

F~gure 14 is a top view of the drug delivery system shown in Figure 13.

Fgure lS is a partial elc~dional view of another ~ ive embodiment of the presenthl~e~ti~Jn with certain coul~l~ t~ shown in a sr~ block diagram form.

Dc~_ "l of the ~,fe.l~,d F ~ ~; ..t~, Presently-p. ,f~,..~ embo~ t~ of the hl~ lion are shown in the above-identified figures - 30 and dPs.,.ibed in detail below. In deDc.il,h.g these various embo~limPnt~, like or idP-nti~ ~l L~;rerence n " ~ are used to identify co.~ ol- or similar elPmPnt~
- Plfi .;~ now to Figure 1, there is shown an ;-.~pl- .~ le device 10 which, in the emk~imPnt shown in Figure 1, is adapted for use as a self~4-~'; ;- P~ l le cardiac pacer 12.
Pacer 12 ~...~ .cs a can or housing 14 which cont~inc an ele_i --' energy source, such as battery 16, and a hybrid circuit 18 which in-~hldP~ elP~ric~ ci~iuil-~ for ~,nc.din~ an electrical pulse to W O 9612S978 PCT~US96/02363 stimulate a patient's heart in a p~ n~A manner. Pacer 12 further inr~ Ps a header 20 which is molded or glued to housing 14 and serves as a ~e ~ ;r~n point for the cle~1lical col-d-~ that are used to transmit the generated pulse to the patient's heart.
T---~ld~d within header 20 is ~ ' 22 and phy~;olcgif ' p~ ~ sensors 32,34,36.
Terminal 22 is electrically i.~te~ ~ with the hybrid ci~ -y 18 by C~ hl~J~ .~ 28 which pass through ~ .~ ' f~lll~u~h 30. Similarly, sensors 32,34,36 are hlt,rc~ -o~l~d to the sensor cil~,uill~ 62 (Figure 2) c~ - rd on the hybrid circuit 18 via co~-h,~ 42,44,46. It is to be ~ ~Y~ that c~r-l~ 42,44 and 46 shown in Figure 1 rnay each co..-~ e two, three or more discrete conductors d~ g upon the ~~..i~ nts of the particular sensor employed.
Con~ 42,44 aRd 46 pass from header 20 into housing 14 via Ç~l~ u~hs 37,38 and 39, r~e.e~ ely. The battery 16 is i.,l~.co~ F ~-d with the hybrid Cil~.uil~y 18 via con-l-Jctor~ 17 in a cu ~ ' manner.
An electrode 50 used to ~;""~ t; the heart is i..ltrcol~~F~led with pacer 12 via col~
(not shown) that are rl~P"~hPtl in a fle~ible catheter 52. The p~ ~ -' end of the ~on~ ctors co-~ ~ wPLhin catheter 52 ~e .. ;- -~e at co---.-oi~. 24 which inrl~des a male co-~--o~lol pin 26.
Pin 26 is inserted into ~ -",;"~I 22 within header 20 so as to ~ ically i..l~ nc~ electrode 50 with the pulse ~,~,n_.dion Cil~ y co~ -rA the hybrid circuit 18 The clc-..~ ; used to ihll~colL~ecl external elec~ode S0 with ~i.,uil.,~ within pacer 12 are co..~ ional and well u ~df!~ ~tood by those skilled in this art. Further details co~ g such i.~erco~ ~ l ;onc are shown, for e~ample, in U.S. Patent Nos. 5,076,270 and 4,860,750, the liC~los~l~es of which are i. c~ t~ herein by this ~-,rt;-~ e. C0~ ,2r 24 jnr~ Pc an outer c~ve~ g 25 of silicon rubber or another material which is both resilient and insulative. Likewise, catheter 52 is covered with an insulative material ll--uu~l-out its length for inc~ ing the cl~l ical conductors that are col~lained therein.
Pacer housing 14 is made of a bioco.~ e~ collosion-LesisLiu~ metal such as st~inl~-c-c-steel or i illm The header 20 prereldl)ly mounts on a welded housing 14 after the hybrid circuit 18 and battery 16 are assembled within the interior of the housing acco~ ,g to cc~ eLlional tPrl~ q~ec Header 20 may be formed from any of a large number of bioc4 ..~ ;I)le materials capable of .~i.,i.. g and incl~ i~ sensors 32,34 and 36 and ~ al 22 Header 20 must also have a tra~.. ii,~ivi~y for cle~lro au ~ energy as r~uil~ by the particular sensor or co ~ tion - ' ~n employed in the jm~pl ' le device 10. The header 20 therefore must be constructed of a suitable m~P~ri~l that co.~l~,cl~ elecl-v a~P~ic energy without excessive absorption or reflP~ctinn, thereby allowing the eml edded sensor to l.~---i~ and receive cl~lr~ ;c energy to and from a point external to the header 20. For many appli~ nc~ header 20 pr~rt; ably is made Ft - ~4 : P~ _~;CA 0 2 2 10 0 7 8 19 9 7 - 0 7 - l o l u ~Z 1~ b P ~18 ' a~ y ~sm or s~rili~ thl "~ polymcr mat~al which is fo~m~'. ir.~ o~er.term~l 2Z
~d 5cn50rs. 32,34 ~r.d 3~. He~ 0 i~ f~rrned ~.o as t~ inctudc a b~ 23 fi~ c~nring c~.-nn~ol 24.
Accor~ingly, sens~s 32,34,36, term~nal 22, as wcll ~ p~iion~ of c~",.1~ 8,4~,44 ~d 4~ me su~"o.~d and iMbedc~ wi~ c cu~ hich a3so scn~ to insul~ nc~ps~
S co~,wns~nts. ~ addition to cp~, ~r mat~ial s~sitable ~ ~ead~ ~ i~c ude ~ass, plas~cs ar~d cl~ctom~ ~uch as Dow ~ s ~elle~nc~M and ~i matc~la ~ h ~s ~phire.
~ efe~g ~w ~o ~igure 2? ~e ~ us ci~ m~ted on hy~rld circuit 18 and er~ployc~ ;~
this ~ L of the i~n~on ~e shown in bloclc dlagrams fc;r~ As sh~w~, mt,ludca ~ thc h~
cu~ 18isFulse~ i nT~ cncui~ rgene~8~ng lheel calpul~ewllichi~de3S~d~sgh ~0 p~;~g c~c~ So for shm~ s;ng tl~e p~tia~trs hc;~t .hly ~ a v~c~ of ?~sc ~ ri~ . ci~uits c~
i~ in the present ~,Lv~ ,f~ 21et those d1~ t~t~d iD U.S. P~t~ Nos.
5~31~T5~ ,04Q~34 ~d 4,830,006, t~c di~l~u~ ~f which ~re ~lcol~o~ h~r.,in in the;r ~e~es by ~is .~r~..c~e. It s~ ld be unde~st~od, ho~cvert that ~e ~esent ir}~ention ~s ~ot li~r~d ~co 2ry pa~fUla~ pll}se ~ circ~it ~ytJli-i c~rcu;;t 18 fi~her inc3udes sens~r ~:~uiby ~2 f~ c~t~olli~ eiYl~ e.~ ",;l'l~
and ~lOCC.S~ti~ e s~nals sent to and ~.Yed ~m ~ rs 32,34 2Dld 3~, ~hich 3~; disposed w~hin ~eadcr ~ va'.u~on az~ wuu~1 ci~cui~ 62 ~l~o ir.~lutes ~e ~ c..b nccessary t~
supply power t~ the se~sor3 32~,3~ andt as 5~0~t~ ie~;~1~ed w~ .~f ;c~ce to F~e 3 belo~, m~ay provide ~c control ~1 lcg;c rl~ces~.y to t~e when Yario~ ga~d or rccciYed. .
Zû ;nem~y circ:~t ~;4 atso ~s mo~ted a;~ ~c }r~orid c~csnt 1~ f~r sto~ ~ous dah, such ~s ~s~
data ~d ~ t}7mc w~ m~ be p~ l into me~Lory c~r~uit ~ ~r wh;~ch ~ay b~
~)lu~ i ~rough an ec~ E,.v2~ .. A ~ C,~,~o, ~ aiso is p~.~ly ir;~luded for reo~ivmg data ~om sensor ~ ~i1uaLv ~ ant ~ ol circu~ 62 ~d for co~tro~t ~e rates at which ~lses a~ g~dt~l b~ pulse ,~ 0. Tim~ 69 aIId rate con~olle~ 68 a~e ~Isc ~h~kd in the 25 hy~rid cir~t 18 a~id mt~l betwee~ "~L~ 6 and p~lsei cc,e~ Ltol 6~. To~r,l.i;~-Op.~ ba~l 66, ~e c4~ er 68 a~d timer 6g C~ to i~creas~ d decr#~e She ~e ~at pu]ses are ge~ Lh~l by ~ ~ tor ~0 ~ a~cul~icc ~ h a ~ ;rc~1 schcduk ~f rate ~ c~es or de~ that arc ~ ~v~ d ~$o ~niC~'Opl~ h ~ther t~ ne~ m~ ~Cte circu~ m~ ~g ~nd rate c~l1~r 68, thesc c~u~ r~ y r~ay be l,c~ !; ~n a s~
dcwUi~gi,~L~L..~ .c:ri ,~6~.
Se~s~ 32,34 a~d 36 a~ .,lt~ L,.~cleid to se~sor e~alua~ md wn~ ;rcui~ 62 ~ria nr~5 42,44,4Q IFig. 1~ l pacer l;~2,3~ l 3~ ay b~ ~y ~a Yanety of senst~S ~pabl~ of sensin~ç ~no~s pl~ys~logical F~ ~ose valuc comlate to D

-heart rate. As ~ ,iously ~ d the pk~ nlqg~' parameters that may be sensed by ~ , ' ' ' e device 10 snd e~, alu~l~ fior use in ~r~ E the heart, providing a defibrillizing pulse or ~ 5 needed medication include, for e~cample, blood o~cygen saturation, ~ilatiOn rate, pulse rate, t~e~d~e, pH value of the blood, the natural atrial rate and the QT interval.
S While three sensors 32,34 and 36 are shown emb~P~d~Pd within header 20 in Figure 1, the invention is not limited to a particular number of s ~- - rC For e-~~ple, in certain appli~tion~, only a single sensor may be l~uir~ or d~ ~ ble In other i---~ eS7 more than one of the same Icind of sensor may be employed in ~he header 20. In such instances, the plu~di~y of sensors may be employed to provide a dirf~ lle~ur~neDt of the sensed physiol~gi~~' pa~a.ll~,Alternatively, or in a~ iticln to such an anr~ge",le.~, an a(i~litionq1 sensor of the same type may be employed as a bac~up or "d-~ sensor, so as to delay or sl the need for surgical iulle~ e,~lion t'hat might othenh~ise be required to replace the implantable device 10 should critica'l sensors fail.
It should dso be nnA~ tQod that the in~,.,.llioll may include more than a single type of sensor embe~dd~Pd within header 20. For PY~mrl~P, r~f.,.. ihlg to Figure 1, sensors 32 and 34 may be used to detect blood oxygen sdlul~lion, while sensor 36 may be a ~ ,~alu.e sensor or a sensor for ~ =~n -~ ;U,~ the rate of blood flow. The types of sensors that may be embedded wi~in header 20 are l~r~lllr~rOUS; the type and number of sensors po ,:~;ol~d within header 20 are limited only by the size of the in~p!~t~llle device 10 and header 20.
There is shown in Figure 3 a more particular embodiment of the hl~ ioll in which a number of electroptic devices or other devices for e~ g and sensing el~ul..agi~ lic radiation are embedded within a ~ urPnt or ~ arenl header of an implantable device 10 for c-.~
and ~ illg signals co-l~s~o~ -g to sensed physiological pa-~UII~ . For convenience, this c~~ of the invention also will be described for use with a pacer 12, the specifics of which were pl.,~iousl~ ~1. It is to be un~lPrstQod, of course, that this invention can similarly be used in a drug delivery system or any other implqntq-~le device.
~PfiP-ring now to Figure 3, pacer 12 in~lud~ps an oxilll~ sensor 70 for detP.~ting the level of oxygen saturation in the blood. More spe~ qlly, O~illl~ relates to the portion of circulating l~mog1obin that has been ! ' dled with oxygen. The extent of oxygen salul~lioll is dependent upon the patient's level of activity, and the PY~ h-~e process between carbon dioxide and oxygen within the blood. The rPI~~ hir between oxygen saturation of the blood and the pulse rate of a patient having a healthy heart is well Un~Prst~. Due to this rel~~ion~hil j ~e present invention may be employed to regulate the pacing rate in ~nse to the sensed blood oxygen level in order to pace the heart at a rate appf~l;~le to the physiological dem~nrl~ of the patient's body.

W O 96/2S978 PCT~US96102363 0 ~ ~ sensor 70 is ~ within header 20 and inrh~dP~ oto~ 72,74 and p'~t~e~or 76. In a pl~,f~ d emboAimPnt~ the p1~ 72,74 c~ e light e~ .gdiodes (LED's). More particularly, LED 72 is chosen to emit light in the red ~.a~e~ for e~ample within the range of 64~660 ,.~;, while pl~ 74 emits light in the infrared wavelength, such as a .. ~ at the isobestic point (al)p-v~ 1y 805 nm) or farther into the infrared ~e~l,u.." such as within the range of 88~940 ~.m. LED's 72,74 will be seqrc~ y turned on and off so as to emit light pulses 73,75 in an ~ g fashion. Phot~A,P~tP~r 76, which may be a con~ D~ or p'~t~Aiode~ will receive the optical signals 77 that are reflect~d from the patient's blood. Thus, the output of pho~P.tP~r 76 will r~,pr~lnt a ~~i od signal first from the firing of the red LED 72 and ,~ s~u~- ~ly from the IR LED 74.
In the ~bodhnent of the iu~ DIion shown in Figure 3, sensor evaluation and control ,i,.,Uill ~ 62 ir.r1nA.~ c...,uill ~ for firing the LED's 72,74 in the proper ~ ~ ~ - e, and for s~ y ~ec~ iLg and ~valua~i~5 the reflected signals. More specifi~ y~ sensor circuil~ 62 int'l~ldps an LED driving circuit 92, control logic 90" , 'ifir~~ n circuit 78, switch 80 and sample-and-hold lS circuits 82,84. Acco~ing to a prQA~Prlnin~_ sc~ re, the control logic circuit 90 will signal LED
driving circuit 92 to ~ L - ~ ~t~ 1Y fire LED9s 72,74, circuits 90 and 92 being p~. ~,.cd by battery 16.
The light pulses 73,75 ~ .ly emitted by LED's 72,74, ~ ,ely, will be reflected back and rece;-.~ by p"ot~.te~r 76 as reflected signal 77. The signal 77 received by photodetector 76 is ~plifi~d by a co..~ alnrlifi -- circuit 78. A switch 80 is controlled by control logic 90 so as to supply the ~plifiad signal r~ce,;ved from photo~letect~r 76 ~ tly to the ~ploplidld sah yle ~-~I-hold circuits 82,84, circuit 82 holding the sensed value as ~leterted by the reflertio~ of red light emitted by LED 72, and circuit 84 holding the sensed value as detert~d by the reflection of IR ~.a~ek .~ll c as emitted by LED 74. The outputs from sample-and-hold circuits 82,84 are provided to a rn~lltipl~~R- 86 which multiplexes the amplified output signal and supplies the signal to an analog-to-digital co~ .t.,. 88. The co.-~e led digital signal then is supplied to microprocessor 66 which, in accor~ce with a p.~?ro~;la.,ul.ed ~l~lill..l., causes pulse generator 60 to produce the ~ opl;d~;ly timed s~irn--l~inn to the patient's heart.
Other cir~.uill~ for r~,c~;~i"g and p-OC~ signals l~ ~ by photodetectors, and for tlic~earl~ g~&.ding al,pr~li~l~ pacing signals in a pre~ ed manner are known in the art - 30 of pulse OAill.~r. For e .. p'c, U.S. Patent No. 4,903,701, hlco.~oral~d herein in its entirely, oses cl~ QCOCi~~ with oxygen sensor control and pacemaker timing, the pow~hlg of- the oxygen se~nc~, tel~ of the sensed oAygen ~ ;o~- values, timing of sensor op&ralion and the ~IP.C~; ~& of the signals g.- e ~ ~l~ by the o~cygen sensor. Thus, the present hl~,.llioll is not limited to the e~ c;n;uil. ~ d~- lil,cd with l~,f~ ,.. ce to Figure 3.

W 096/2S978 PCTrUS96/02363 To en~ble the pulse o~i...~ sensor 70 thus de~clil.ed to operate e~ ly, it is ihllpo.t;
that the header 20 persnit the desired ~ h ~ of light to pass through the header with an optical transmission elroc~ive rate of 70%. Acco-din61y, it is pl.,fe.,~ that the ~q~eriql from which header 20 is formed have the following ~L~a ~ ;CS~ high dielectric ~-- and dielectric strength, USP Class VI bioc~mpatibility, flatness of its optical ~ ",ic~i.," curve C~ p. -~ing the desired .. a~_l~lll~ and low changes in optical properties Ill~uu~llu~ll implant life.
Presently, the most pl.,f~,.r~d Illdt-,.ials for header 20 are Emerson & Cuming Stycase~
1267 or 1269 tra~r- ~l, high ....~a~,l casting resins or Epo~y Terhnology, Inc. Epo-tekD 301 spectrally tra~p, ~ epo~cy which have an appropriate ~ -;Ol- b~n 900 nm and 350 nm.
Thus, the ~ ~u_h~ sensor 70 and cardiac pacer 12 shown in Figure 3 provides the -~V~ul~g~ offered by pulse u~ ll~y terhnrlcgy but, in contrast to the prior art which typically f~uif~ ~re~;-q-li7~d leads for housing the LED's and pholol~,l,lol~, instead provides a self-contained i~t~ d pa~e that is not sll~ceptible to the ~..r~ irql stresses hl~ d to - -' pacing leads. The O~illl~y sensor 70 and pacer 12 include windowless en~losllres and thus are less li!~ely to e~cpaience seal failures or to be infiltrated by colf~sive and destructive body fluids.
Another ~ em~iment of the present invention that is useful when employing rh~to~ and rhotodete~rs as sensors is shown in Figures 4-7 in which one or more ele~illu~ focl~;ng devices 94 are embedded in or formed in or on header 20. Referring first to Figures 4 and 5, focusing device 94 may colll~lise a pr~rolllled lens 96 of glass or other ~ll.~:,ilion. Lens 96 is po~:l;n~i a~ 1 the outer surface 95 of header 20 when header 20 is formed such that reflected optical signals 77 are better focused on photoAetector 76. More particularly, lens 96 is selected and positioned within header 20 such that its focal point is ~ ~1 on the light sensing surface 71 of photod~P~r 76. Similarly, lenses 97 are retained within header 20 vJj~ l outer surface 95 so as to more pl~isely focus the light emitted by LED's 72,74 at a focal point a pr~ .--:--~l distance from header surface 95.
Referring ww to Figures 6 and 7, focusing device 94 may similarly colllpli;,e a Fresnel lens 99 that is created by forming a series of CO '--t~ iC grooves 98 on surface 95 of header 20.
Grooves 98 may be laser etched or otherwise cngld~ on the header surface 95 and, like lens 96 shown in Figures 4 and 5, will serve to focus the reflected light signal 77 on the light sensing ~ surface 71 of ph~tod~PtPctor 76. Although not shown, a similar lens 99 is pl~feIdbly formed in header 20 ljr~-1 to LED 72,74 to more pf~;sely focus the light pulses emitted from LED's 72,74.
While two distinct ele~ gn~i~ focusing devices 94 have been shown in Figures 4-7, it should be nnAPlYt~ od that the present i.. ~ nlion is not limited to the use of the lenses 96 or 97.

CA 02210078 1997-07-lo Instead, any of a variety of other means to focus e]f~lr~ energy may si~il~ly be h~lu/~. For example, a dislc of lransparent or tra ~nl.~cPnt n qtPri~l having a dirr~.-l indeA of ;OI~ than the .~ ~ ' of header 20 may l-' . ;3C be used as a foc~c;~ device 94 and f ~ l-edc~f~d within or oll~ .. ise retained on header 20.
When; k.~ pulse oAi~~ t ' -logy, it is the ratio bch.~ oxygen sduldion of the arterial blood flow, and that of the venous return flow, that is il~l~l in d~ "'; - ~E wL~hc~
the patient's heart is r~ g P~JC.IY. See c.g. Inbar, et al. "De.~lop~ 1 of a Closed-Loop Pacemalcer Controller Pf~l g Mixed Venous O~cygen Saturation Level", IEEE Trans. BME
35(9) (1988), at 679 690. The oximetry sensor disti~guishes the arterial blood flow by sensing the ~r~ure pulses created in the arterial blood flow by the pe~iodic co--~ ;on of the heart.
Conventional pulse OAiu.~,h~r sensors are motion intolerant in that InV-/Cilll~.nl of the OAilllCh~f sensor, as may, for e-~mp'~, be caused by a patient jogging or otherwise exercising, may cause the sensor to provide a signal similar to that caused by the arterial pl~;,ure pulses. This is because such e~e.lion may cause relative l..o~e.~ between the sensor and the s.lllo~di~ tissue. Such motio affects the thi~ of tissue between tbe light source and photQdete~r, thc,efure altering the ~ion of light as it travels along the light path. R~ili~e motion may mi nic arterial pul~ on such that the UAhll~ / sensor is unable to discern the dirr~ce between pulses resulting from motion and those resulting from the arterial activity. However, by posiliolli-lg pholoc..-ille.~ 72,74 and photo~lP~t~P~r~ 76 in the header 20 of i~pl~nt~l-le device 10 as described here below, a dirrere.~ .ll may be taken which can Plimin~P, the problems that sensor motion may cause in col.~,..;ional OAilll~y sensors.
More spe~ifi~-lly, and l~fel~ to Figures 8 and 9, two pairs of LED's 72,74 and two pairs of pl~o~e~ 76 are po~ d such that LED's 72a,74a and photodetP~tor 76a face in a first direction relative to a plane 100 which bisects the pacer 12, while LED's 72b,74b and p'~ P~r 76b face in the opl)o5ile dir~tion. In this manner, optical signal 77a d~PtPcted by phot~Pte~r 76a may be cul..~ d by ~..;clupr~cessor 66 (Figure 3) to optical signal 77b det~ted by phot~A~ec~r 76b for each. Through this cv--l~u;~n, the effect that ~llo~.llcnl of the pacer 12 would otherwise have on the sensed signals can be ~Plimin~P~A A simple algorithm used to process these signals in order to elimin-~e the effects of mo~ would add the rligiti7P~A signals - 30 dPtPrtP~A by photod~ 76a and 76b while LED's 72a and 72b are on. The same would be done when LED's 74a and 74b are on, providing the two signals ~ec~ for calculating oxygen - - - ~r~u~hu~1 the blood flow cycle.
Another e.--l~~ of the present i--~ tion is shown in Figure 10. As previously PA the h.~_.,1ion is not limited to any particular type of sensor, but instead may be employed with any device capable of ~letPrtir~ or .~g ~.; ~g a physiological parameter useful in W 096125978 PCTrUS96/02363 op~-ly ~i 1; ~ the heart or .~ .c:.~g needed InF~lir ~ion or providing other desirab1e ~e ~~. F ~~ In certain instances, it may be alv~ to detect the ele~lrocdrdiogram of a patient or ulhe.-.isc make use of a body's tissues and fluids as a bioelectrode in order to .n~u.e a ph~ slo~i~ ' parameter. In the e-~ shown in Figure 10, sensors 32,34 col-.~ri~e S electrodes formed by conductive plates 102 that are embedded within header 120 of pacer 12.
Header 120 is formed of an cle~i 'Iy insulative ~ ' having a relatively high diele~ic constant. Plates 102 form capa~iti~ly~oupled bio~ -udes to sense electrical signals that are related to a desired ph~ ~cgi ' p= .. ~-~
As shown 5~h~ 'ly in Figure 10, plates 102 are di;,posed at a pred~ - .--;-.~d distance from outer suRace 124 of header 120 and are cu-- ~ d to high input hll~ buffers 104 which, for e~ample, may be J-FET unity-gain buffers or single FET ~ . Rec~ l~e of their small size, buffers 104 may be mounted within header 120 imm~ .ly "' ~ nt to places 102.
Alle..ld~ ly, buffers 104 may be in~ ded as part of the Cil~,ui~l ~y housed within housing 114. The outputs of buffers 104 are co~l~led to an amplification circuit 106 which provides a signal to sensor evaluation circuit 108. The output from evaluation circuit 108 is co.. --.-~ d to a .. ic.u~rdcessor or control logic 66. Dcl.e~ ~ upon pre,(l~ -fd instructions prog~ cd into the control logic 66, the ~,prû~,.iate stin~ ati~ pulse will then be g~ ne~ded by pulse ge.lerdlor 60.
Figure 11 s ~ 'Iy depicts the equivalent circuit for the sensors 32,34 shown in Figure 10. Bio~ source 112 may, for example, r~.~se.lt the c1c~l-ucal-1iogram which is c~acitively coupled to plates 102 by a fielwu-~ 116 which .ctJl~cllb the impeAq~es 118 formed by the patient's blood and various tissues and the dielectric material from which the header 120 is formed.
To provide for the al)~ro~J~iale capacitive coupling, it is impo.~ll that the volume r~ii,livily of the header materi~ be higher than 1 x 1012 ohm-cm. When used in a pacer 12 as shown in Figures 10 and 11 and used to sense the electrocar~lio~rvqlm~ the header material p.~f.,.ably will have a 2~ dielectric co~ above 3 (such as, for example 3.8), a volume rcsi~Livily above 1 x 10l2 ohm-cm and the electrodes 102 wUl be di~,osed ~pl~u~ ly 0.2 mm from the outer surface 124 of header 120. An epo~y that is particularly suited for use in forming header 120 is Emerson & Cuming Stycast~ 1267.
nalively, where a particular physiological parameter may be better sensed by means of a .~ tive coupling, rather than through the c~ac;ti~e conrling just described, the material of header 120 may be selectively m~ified to have a lower dielectric c.~ or e-~mple,~ ~ir~lly cQ.~ I~ive particles such as CQllOi(~ pl~in~rn may be added to an epoxy header material before it sets, such that the hardened material will have a lesi;,livily of a~prox;~ ly 1 ~r~P,j j,~

W 09612~978 PCTrUS96102363 As stated sbove, the presenlt i..~ liu may also be; . l~ l in j~l~-~tr~ le, closed-loop drug delivery systems. Co~ io~ such systems are typically one of two types. A first such system is one having a sensor that is imrl~t~ ~ ly from the ;"~ e drug delivery device.
An e~ample of such apparatus is ~i~rlosed in U.S. Patent No. 5,041,107, the ~lic~losnre of which S is inco.~ d herein by this rererence. A second type of i~r!~ lt~1~1e system is SIIU~IU~Cd such that the sensor is housed along with the drug delivery apparatus. An e~ample of this second type of drug delivery system is shown in U.S. Patent No. 4,373,527, the ~ rlos~e of which is also incorporated herein by reference.
~P.fPt ri~ now to Figure 12, there is shown ~ pl ' le drug de1ivery system 130 which generally; A'lvd~s sensor body 132"~1ectrically operable drug delivery l r~ n~ .. 134 and catheter 136 disposed the~d~ Sensor body 132 generally inr~ c a c~ hl~ 14 which houses battery 16 and hybrid circuit 18 all as ~ iou~ly d~ ibcd with l.fe,ence to Figure 3. Sensor body 132 further ~ ~' '~~ a header 20, also pi~iuusly described with l~Çere~ce to Figure 3.
Header 20 seals and ;~ fs phys~ ogirq-l p~u,u~ sensors 138,139,140 as well as t~minql 22.
The hybrid circuit 18 inr~ sensor l:v' on circuit 141, IllC.lloly co~l~pone~ll 142, ".,c.up.vcessor 144 and a pulse genl.alul 146.
The cc~..l;~.--dtion of sensor evaluation circuit 141 is dependent upon the type of phyciologir l p~dlllet~. sensors 138-140 that are employed. In turn, the choice of physiological p~ - sensors 138-140 will, in part, be dependent upon the particular drug that is to be ~ ed via imrlqn~ le drug delivery system 130. ~lthough the present i~ ion is notlimited to any particular im~ ~ble drug delivery system, it may be used ad~ ~usly in an implantable insulin delivery system. The d~t~.,llh.i,l~ factor in whether to a~ l~ insulin is the measure of glucose circulating in the patient's bloodstream. As with oxygen saluldlioll, measure.ll~t~ of c~cul~illg glucose may be made by photoelectric means. For example, in the inlrl '~le system 130 shown in Figure 12, devices 138 and 139 may be LED's 148,150 chosen to emit light in the ~ bll.c of 9.68 micl~oll,l,t,c.:, and 3.42 micrulllct~ C_livt;ly. Sensor 140 may CO~ C pho~ ul which will receive reflected light from that emitted by LED's 148,150. The signals from pholoL,d~ii,lol 139 may be sampled by sensor evdlud~ion circuit 141 which, in this embodiment, would be ,--l-~ 'ly i-l-ontir~l to the sensor evaluation circuit 62 d~ ~ il,ed wi~ r~ r~ ~lce to Figure 3. Based on the values sensed and evaluated, microprocessûr 144 will cause pulse ~ - 146 to g_,l_.dle an electrical pulse that will be ~ Y1 through the c~---h,~ eQ~ d in catheter 136 to drug delivery ~ ... 134 which will dispense the 3~,pr~ ~ ! amount of insulin ~ se thereto.

r~--v~ ~r 1~ . tCA 022l~00~5,78_~l927 ~ 10 gla~ C~c~~ lb P.~9 lS43-00531 ~ Re~lacr~lt Sheet A drug dcli~ sy~tem of the type hav~ng ~c se~sor housed wi~ tht ~ del.~ pp~;~
~nd whi&~ ~.myl :~y~ ent im~cntion is .sl70wn iri Figu~es 13 and 14. ~ shown. implant~ble dn~
delive~y sy~m 160 ge~ ally ~nciudes con~ne~ 162 and he~r por~on 1~4.
Cantaincr 1~2 i~ madc of a ~ cv~ 4t~ ~ten~l suok Q~ stni~ l or ~tnnst:m 2~d i~
S ~cncsal~y di~ded in~,~ u~to ,~ur cu~ rd~LLLL~ or chal~b~ let chsm~ l~r~;; a r~,sc~.vvl~
chambe~ 166; ,~ pump chamber 1~7; and an clcctro~ics charnber 1~. ~let cham~ 15~ con~i~s q supply post 17û u~ich inciutes ~ sclf-~ ". ~..k. ~ c 171. To supp~r insul~ ~r ~cr d~rlu~
drug w drug deliv~ sy~ n 16~! the drug is ~jected by means of a L~ -;c nsedIe ~at is ~se~ted thr~u~h ..- "1.,- lr 171. ~let chamber 165 is in fluid cQ~n~ c~ti~n wi~ oir 1~6 and, wh~
a requ~ he dn~ will ~ ~wn fiom inlet c~ into res~oir 16~ rough ~ ~I~d duct ~nat sh~wn). P~m~p ch~mber 167 include~ pu~p l~g ~hich, whe~ Ll,~iYilig ~e ~rlu~r~ ~ si~ ficm the c~ d wi~n el~c~,~ hamber 1~8, ~ill p~p *Le ;L~ryL~y~ ~olmt ~f "~ vl~ cham~cr 1~ into ~he pat~c~t'~ body via pctt 174.
~o~ 162 ~cludes ~ ap~rt~e 17~ ~i~ 14~ ~to ek~ c~am~r 15~. Hea~er 1~
l; clbse~ ~pert~e 17h and s~ais ~e p~iolo~c~l y~.,l.~ ter ~s~s 1 J7, 17~, 17~ there~ ~lr~r7Tr~C
~ 16g ~ouses batl~Lies 16 ~d ~bnd ~nt 18. Tlte hybrid clrcuit 18 c~t3~s the sens~r cval~ti~rn circu~, ~emcry, ~u~ ,.Y ~io~.. sly dr~

v i(~u~ C ~ lioll may b~ cmpl~ Wlth a51y of a varlct y o~ physiDlogic~tl h sens~rs empl~y T ~TY5 ~d p~ ~be~ o~ o~er r~
~, ~e matErisI ~d in f~mmg h~der 16~ will be selected to a5 to h~ve the op~ u~L~.~
neces~y ~ achieve ~e d~ed light h~n~ icc;~ r ~*rnrl~ a~ y haring tbe p~sical ~- 4.e~ s .i~.,~.~d ~sk~ with ~ r~ce to hT~atcz ~0 in Fi~ure 3 is ~ uitet for use ~n ~e i~rt~T~T~Ic dn~ ddivcry sys~ern sh~ . m ~ nd 14.
2~ l~ne L~ s of ~e p~t ~J~,~Iio~ C~L also be ~lo~l ~s a telerne~ l~nk TJse,d tO
h~=it data ~ ~ to and ~ ~e ~t~le de~ ef~ tf) Fi~Dre 15, i" .~.t~
deY~ce 180 is shaw~ ha~¢r ~ ~,1~, 14 aIld headc~ 2~. Cc!nk~t~ 14 houses a batk~y (no~ shown) r~n~ ~t I~ ~ich aon~i~s ~e dec~onica ~rc~ b~th ~co fillfill t~# pnm~ fi~~ ~f the ~ T~ e dence, far example~ ~iac pac~ or drug de~i~y, as well a~ ~e C~ ~L~I~ L"
30 requ~ v~ betwe~ei~pt~nt~bl~d~ceanddatah~.~cr~ hatmay be loc~ted 1:~ oubiide t~e bo~ ~r ,' t ~ rnrwbiy ~ t~ lnrltnh1a d~i~o I~0. ~net~leme~ }~ tS C~ r'd withi~ hCadCI 20 and can ~r~rl~ any of a numb~r cf typ~s o~
~m~mii~ "s~d re~ ~ tl~ de~ails o~ which wtll depend o}l the type of c- ,. . ". ." ~ ~c d~e~
p~ r sllit~d ~fio~ n thc prese~t ~ti~ is c~ zti~n li~ 182 w~ch ~,mploys a 35photo~ uch ~s r~ and a photod~et~. such ~ l,t.~l.d.

p~A~~0 p CA 02210078 1997-07-10 rc~ 55 F~l '-~L~ r~tON TC qC~ 6Cc~ P.10 ~5~3-0050~ Repl ~C~rn~nt sheet ,ul~t4h~;.hn 18~ p~mit ~n ~ptical link bctw~e~ impla~able .lc~icc 18~ 0 that, ~h~ ~la~ed zgsmst the p~ient's s3cir~ lY2 at a i~tio~ ~t to heade~ 20 can ~nsm~t ill;t~uS:t;u~s via opticsl sig~al 1~4. Ih~sç i~ ;u~. a}e recei~ t ph~tQd~tcet~r lr~t,~ and l ~d;l ;~ p ar ~ r ~ d~ Circ~Sr 196, ~e output of whi~ m~y b~ used .o 5 L~r~ mi&.~L~r lg~ or be stared i~L mem~ pac~,e 1~9. Simil~trly, d~ta ga*Le~ed by i rr ~ tst~lc ~e~ 180~y~ t~t~to~xbel~0by ~DofL~D l~lw~c4 ~ ~xn~ ~
tke ~ v~ e si~l f~om mi~o~)~c05st~l 198. a~ld signal t ~n~liti~ntn~ and LEI~ ~iYel' Ci~Uit Ig~, will tr~2lsmtit aptical sig~al 193 to p~obe 190. As ~;111 be u..d~.~tl~d by ~s~ ~killed mt the ar~ whe~e ll"~ .r;~ dence 180 Il;tclu~s ~ tcl~.lLt~ lc 1~ as. ~ ~, head~ should ~ve 10 optical q~ies a~d ~uuy~ ~ such as those pre:Yio y ~lcs~ ~ for header 20 sbown ~n F~ 3. It should also ~e ~ T. "~ fT ~at ~e telcmetry Ii~ 2 ~ not l~ted t.O a r~tocT~-~L;~ mea~s, but ~nstead may se~d a~d ~eceiYe ~ y by ~r mea;ls, for exa~ple, ~ t~ m of Iadiof~e~u~ 3i~als~l which event, anten;las, ~r ~an ph~,lu. .~ . a a~d p~t-tnrl~t~rC would bee~dmh~de~20. Siinilarly,~ Y~ tl~ edtoameansforcne~lt~ wi 1~ an extemal probe l ~ t mst~ ;~ay be c~y~d to c~ emotely ~aiLit~
~;~pl~ntat~le de~ at may, f~r ~;ampk, includc physi~lo~ical [ ~ ~ "~ ~ se~sors s~ch ~s inU.S.P~ent~o~ t,886,0~4.

AMENOED SY'cT

Claims

Claims What is claimed is:

1. An implantable medical device (10) for implantation into a living body, said device comprising:
a container (14) having a chamber housing electrical components therein;
a header (20) attached to said chamber to close and seal said chamber;
at least one sensor (32);
and leads (42) electrically interconnecting said sensor and said electrical components, characterized in that said sensor is sealed within said header.

2. The implantable device of claim 1 wherein said sensor comprises a physiological parameter sensor.

3. The implantable device of claim 1 wherein said sensor comprises a telemetry transducer for communicating with a device remote from said implantable device.

4. The implantable device of claim 1 wherein said header is made of epoxy.

5. The implantable device of claim 1 wherein said header is made of a ceramic material.

6. The implantable device of claim 1 wherein said header is made of plastic.

7. The implantable device of claim 1 wherein said header is made of glass.

8. The implantable device of claim 1 wherein said header is translucent.

9. The implantable device of claim 1 wherein said header is transparent.

10. The implantable device of claim 1 wherein selected portions of said header are made of a material having a volume resistivity less than 10 megaohm cm.

11. The implantable device of claim 1 wherein said header is made of a material having a volume resistivity higher than 1 x 1012 ohm-cm.

12. The implantable device of claim 1 wherein said header has a dielectric constant greater than 3.

13. The implantable device of claim 1 wherein said header has high optical transmissivity to wavelengths between 350 nanometers and 900 nanometers.

14. The implantable device of claim 1 wherein said header has high optical transmissivity to wavelengths between 3 micrometers and 10 micrometers.

15. The implantable device of claim 2 wherein said sensor comprises a photodetector (76) capable of receiving through said header an optical signal indicative of the measure of a physiological parameter.

16. The implantable device of claim 15 wherein said sensor further comprises a photoemitter (72, 74) capable of emitting through said header an optical signal to be received as reflected light by said photodetector.

17. The implantable device of claim 2 wherein said sensor comprises an oximetry sensor (70).

18. The implantable device of claim 1 further comprising an electromagnetic focusing device (94) on said header.

19. The implantable device of claim 18 wherein said electromagnetic focusing device comprises a body of material having an index of refraction that is different from the index of refraction of said header.

20. The implantable device of claim 18 wherein said header includes an outer surface (95), and wherein said electromagnetic focusing device comprises a plurality of grooves (98) formed in said outer surface of said header.

21. The implantable device of claim 18 wherein said sensor includes a sensing surface (71), and wherein said electromagnetic focusing device comprises a lens (96) attached to said header, said lens having a focal point adjacent to said sensing surface of said sensor.

22. The implantable device of claim 1 wherein said header includes an outer surface (124), and wherein said sensor comprises a conductive plate (102) disposed in said header a predetermined distance from said outer surface.

23. The implantable device of claim 22 wherein said predetermined distances is within the range of approximately 0.1 mm to 2.0 mm.

24. The implantable device of claim 1 wherein said header includes a plurality of sensors (32, 34, 36).

25. The implantable device of claim 24 wherein said plurality of sensors include a first physiological parameter sensor and a second physiological parameter sensor, and wherein said first and second sensors measure different physiological parameters.

26. The implantable device of claim 25 wherein said plurality of sensors include a physiological parameter sensor and a telemetry link.

27. The implantable device of claim 24 wherein said plurality of sensors include a first oximetry sensor having a first photodetector (76a) with a first light-sensing surface and a second oximetry sensor having a second photodetector (76b) with a second light-sensing surface, said first and second photodetectors disposed in said header so that said first and second light-sensing surfaces face in different directions.

28. The implantable device of claim 27 wherein said light-sensing surface of said first photodetector faces in a direction substantially 180 degrees apart from the direction faced by said light-sensing surface of said second photodetector.