CA2200894A1 - Implantable pharmacological defibrillator system - Google Patents

Abstract

A catheter (206) for use with a rhythm control device (16) which enables to deliver pharmacological agents and electrical signals and comprising: an elongate body (132B) having a liquid lumen (200B) extending longitudinally in said body, first and second electrodes (144B, 208) spaced longitudinally along the peripheral surface of said body, first and second electrical leads extending longitudinally within said body, a valve (164) on said body at an outlet port (142) for enabling liquid to flow in said lumen, and connector means for attaching the proximal end of said elongate body to the housing of a rhythm control device.

Description

2200~q'~

IMPLANTABLE PHARMACOLOGICAL DEFIBRILLATOR SYSTEM
FIELD OF THE INVENTION
The present invention relates generally to medical devices, and more particularly to an implantable system for the delivery of drugs and for providing electrical therapy to a patient's heart to correct arrhythmia.
BACKGROUND OF THE INVENTION
Implantable drug pumps and the like are known from Ellingwood, U.S. Patent No. 4,003,379 and implantable ph~ eological defibrillators are known from Cammelli, U.S. Patent No. 5,220,917. These devices have shown that the automaticdelivery of drugs can be effective for the treatment of heart arrhythmia. However, the most ~I~lo~fiate techniques for sensing disease conditions and for invoking ph~nn~cological or electrical therapy are not well resolved in the current literature.
There are also numerous issues related to the successful integration of drug therapy with electrical therapy and the ~ylo~,l;ate devices for delivery of the drug, which are addressed by this disclosure.
SUMMA~Y
The present invention proposes both structures and methodologies for an implantable rhythm control device to supply ph~ rological agents and electrical therapy in response to a ~lrtecte(l ~lhy~ lia. The implanted device may be used both for the tre~tment of atrial and ventricular allhy~llllia, depending upon the choice of the lead system and the site of drug delivery. In general, electrodes are placed on the lead system to interact with the heart muscle. These electrodes provide both sensing information to the implanted device as well as to deliver pacing stimuli or higher energy defibrillation shocks at a~ ,fiate times to the heart tissue. The implanted device further includes a drug reservoir and associated pump system for delivery of the drug through a catheter to a location, either within the heart or proximate the heart which allows the drug to be absorbed in to the circulation of the heart. Higher energydefibrillation therapies are contemplated as well, and it is believed that cardioversion plolllplly after drug delivery may prove to be particularly effective.
For the tre~tment of atrial ~lhylhlllia, the device will dispense an anti-~lhy~ lic drug, either outside of the heart in the superior or inferior vena cava, or within the heart within either atrial or ventricular chambers. This drug will reach the 2 2 ~ L~
atrial muscle mass through systemic circulation. Drug delivery may be timed to occur during the atrial diastolic time period to increase the rate of drug transport or absorption to the target tissue.
For the treatment of ventricular arrhythmia it is preferred to dispense the drug in 5 the coronary sinus which forms a part of the ventricular vasculature. Once again delivery may be timed to improve absorption of the drug by the tissue. Both the detection criteria for initiating the delivery of the drug or a ph~rm~cological agent, as well as the integration of drug delivery with other forms of therapy, are set forth in greater detail below.
For the treatment of ventricular ~lyLhlllia it is desirable but not absolutely necessary to have a relatively high energy cardioversion system which can provide higher current shocks to convert the ~lhyllllllia should the drug therapy prove insufficient. A plefe.l~d catheter structure and dispensing valve are also disclosed. It is expected that lower energy cardioversion will be useful in conjunction with drug1 5 delivery.
BRIEF DESCRIPTION OF THE DRAWINGS
An illustrative system is shown through the several figures of the drawing, wherein identical reference numerals indicate equivalent structures throughout:
Fig. 1 is a sçhem~tic view of the overall system;
Fig. 2 is a table which shows several classes of the implantable ph~rm~cologicaldefibrillator device;
Fig. 3 is a table which shows the locations of drug delivery for various allhylhlllias;
Fig. 4 is a diagram depicting the geometry of several lead configurations for use with an implantable device;
Fig. S is a s~.hem~tic block diagram of the imrl~nt~ble device;
Fig. 6 shows a lel,resellt~ e wave form of atrial and ventricular signals;
Fig. 7 shows an illustrative treatment flow chart which is implemented by the implantable device;
Fig. 8 is an enlarged fragmentary view of an end portion of a catheter for use in the system;
Fig. 9 is an enlarged cross sectional view of a catheter;

wo 97/04834 2 2 0 0 8 9 ~ PCT/USg6/12279 Fig. 10 is an enlarged cross sectional view of a catheter;
Fig. 11 is a fragmentary view of an end portion of a catheter;
Fig. 12 is an enlarged cross sectional view of a catheter;
Fig. 13 is a fragmentary view of an end portion of a catheter;
Fig. 14 is an enlarged cross sectional view of a catheter.
DETAILED DESCRIPTION
FIG. 1 shows an implantable pharmacological defibrillator (IPD) 10 connected to a lead system 12. The lead system is shown schematically and portions of the lead system may enter the superior vena cava (SCV), the coron~y sinus (CS), the atria as indicated by the right atrium (RA), or the ventricles as indicated by the right ventricle (RV). The can 16 of the IPD may form an electrode and the lead system 12 may include a subcutaneous plate electrode 14. A septum 18 is also provided on the can 16 to permit access to the drug reservoir contained within the can 16. There are a number of electrode locations along the catheter system 12. Electrodes may be located outside the heart as illustrated by superior vena cava electrode 20. Other electrode locations outside the heart include the can electrode 16 and the subcutaneous electrode 14. Electrodes may also be located within the heart as illustrated by atrial electrode 22 in contact with atrial tissue and atrial electrode 24 floating in the atrium. Electrodes may be located in the coronary sinus illustrated by electrode 26. An electrode may be placed in the ventricle as well as illustrated by ventricular electrode 28. The majority of these electrode sites can be used as electrical references for unipolar or bipolar sensing and pacing. Groups of electrodes may be electrically coupled to from defibrillation electrodes for the delivery of higher energy conversion pulses or to provide multiple sites for monitoring cardiac rhythm.
The IPD contains a reservoir (not seen) which is coupled to a lumen within the lead system 12. A flap valve shown as a circle on the diagram of Fig. 1, will allow the IPD to deliver the drug at any one of several locations. These locations are shown in the figure as SVC site 30; RA site 32; CS site 34; or RV site 36. It should be appreciated that it is highly unlikely that a device would possess all the electrodes and drug delivery ports set forth in the schem~tic diagram of Fig. 1. A fully functioning IPD system would typically be a subset of the electrodes and drug delivery sites enumerated and disclosed in Fig. 1. Typically the IPD device will be targeted to a specific ~lLylhlllia and a suitable pharmacological and electrical configuration will be selected based upon the disease and the therapeutic protocol.
Fig. 2 is a non exhaustive table which shows several classes or categories of IPD
which are contemplated within this disclosure. Column 40 names the device with a5 Roman numeral. Column 42 indicates whether an atrial sensing function is available in the device. Column 44 indicates whether there is an atrial pacing function in the device.
Column 46 indicates whether a ventricular sensing function is available. Colurnn 48 indicates whether a ventricular pacing function is available. It is anticipated that each type of device will dispense drugs and that for any given type of device electrical 10 defibrillation backup which may be desired.
For example the class I, class III and class V devices will include atrial sensing and ventricular sensing. These devices can monitor not only the atrial electrocardiogram (ECG) but the ventricular electrocardiogram as well. Thus the V-V
interval as well A-A intervals are known to the device. In addition the actual A-V
15 conduction time and V-A time interval are known. These sensed events permit relatively sophisticated algolilhms to be used to ascertain the existen~e of an atrial ~hy~ ia and to distinguish atrial arrhythmia from ventricular ~lLylhinia. The electronic structures to collect and use of this type of information are well known in the pacing arts and one of ordinary skill in this art can select and implement the n~ce~ry structures without 20 undue ~x~.hllentation. The principle advantage of knowledge of both the atrial and ventricular rhythms is the ability to monitor A-V dissociation and to clearly distinguish atrial tachycardia episodes from conducted arrhythmias. As discussed later several versions of the device use this information to select an appl~E,liate therapy.
Devices which include a ventricular pacing function such as device in class IV
25 or class V can provide backup bradycardia arrhythmia pacing which is desired with certain drugs which tend to induce bradycardia. Although there are numerous bradycardia ~lhy~.~llia pacing protocols including DDT mode and DDD mode, it is expected that the relatively simple VVI mode pacing will be a suitable adjunct to most drug therapies. In instances where an electrode set is in contact with the atrial wall as 30 seen by electrode set 22 (Fig. 1), DDD or DVI or other atrial pacing modes may be selected. It is expected that atrial pacing will be a useful adjunct to drug therapy.

WO 97/04834 2 2 i~ 3 0 3 ~ 4 PCT/US96/12279 s Fig. 3 is a table to depict illustrative locations for drug delivery sites for various arrhythmias. Systemic delivery of drugs has been common and there are drawback to this traditional form of therapy. Many drugs are not uniquely anti-arrhythmic. In some instances a drug can be pro-arrhythmic depending on the clinical symptoms of the5 patient. Another serious problem is that the margin between an effective dosage and a toxic dosage may be quite small when used systemically. In the present disclosure these concerns may be addressed by site specific delivery. It should be understood however that over time any given drug will be found in some concentration throughout the entire body. The purpose of site specific delivery is to produce a therapeutic dose in the target 10 tissues quickly after the onset of an arrhythmia. For this reason the sites shown in Fig. 3 are preferred but not nece~rily required to treat the enumerated ~hyll~lllias. For example column number 51 corresponds to the delivery of a ph~rm~cologic agent ordrug into the right atrium from site 32 (Fig. 1). A less l"ere"ed location for drug delivery is indicated by column 50 which corresponds to site 30. It is believed that the 15 optimal time for delivery at this location is during the repolarization time for the atria.
In general synchronized delivery during ventricular systole will result in quicker uptake of the drug by the atrial tissue. In contrast to the optimal locations for atrial tachy~,hy~ ias the ventricular ~hylhnlias are best treated by delivery of the drug into the coronary sinus at site 34 as indicated by column 55 and column 57. The 20 coronary sinus forrns the outlet for coron~y circulation and ~etlo~e.rusion may ca~y higher concentrations of the drug directly to the ventricular mass. A less preferred location or site for drug delivery is in the right ventricle at site 36 as indicated by column 54 and column 56.
Fig. 4 is a diagram depicting the geometry of several lead configurations for use 25 with an IPD. These configurations are not int~n-le~l to be an çxh~ tive list of the combinations and perml~t~tions taught in connection with Fig. 1 but rather lel),ese,ll several l~lcfc~l~d mechanical configurations for atrial and ventricular applications. In the figure column 62 corresponds to the superior or inferior vena cava when the lead is - implanted. Column 64 corresponds to the position of the lead with respect to the 30 location of the coronary sinus. Column 68 corresponds to location of the right atriurn while column 70 corresponds to the location of the right ventricle.

WO 97/04834 2 2 il O ~ 9 4 PCT/US96/12279 Lead 60 is a configuration well suited to the treatment of atrial tachycardia orfibrillation. The lead 60 is a single pass atrial and ventricular lead for dispensing the drug within the superior vena cava though a port valve at site 30. A pair of floating bipolar atrial electrodes 24 are provided on the body of the lead 60 in the right atrium 5 for sensing the atrial activity. It should be appreciated that the electrode pair can be used for bipolar sensing of atrial activity but that a single electrode at that site could be used in unipolar mode as well. At the distal tip of the lead 60 a ventricular electrode 28 is provided for both sensing and pacing the ventricular tissue. The electrode is shown in the most distal location but a tip and ring or bipolar rings at the distal tip are a less 10 preferred alternative. The lead 60 is relatively easy to position and the atrial sensing function can be combined with the ventricular sensing function to determine the existence of a treatable atrial arrhythrnia. Once an arrhythmia has been declared the device will dispense a suitable drug from a port site 30 located in the vena cava.
Lead 63 is a atrial J-shaped lead for positioning the atrial electrodes 22 into 15 contact with the interior atrial surface. An illustrative ventricular lead 65 is positioned to place the ventricular tip electrode 28 into contact with the ventricular tissue. The drug deliver lumen is located in the ventricular lead and the drug is dispensed at site 36 in the right ventricle. In general this pair of leads may be used to treat ventricular tachycardia or ventricular fibrillation. It should be noted that tines have illustrated as a method if 20 lead fixation but that screw type fixation may be used as a less p,er~l,. d alternative.
Lead 67 has a soft distal tip 71 adapted for insertion into the coronary sinus. The bipolar electrode pair 24 are located within the atrium and can be used for sensing atrial depolarization. The port or valve for drug infusion is located at site 34 within the coronary sinus itself. The companion ventricular lead 69 has a distal electrode 28 for 25 pacing an sensing the ventricular charnber. This configuration is especially well suited for the treatment of ventricular ~hy~ ias.
Lead 73 is an atrial J-shaped lead for the atrium with a pair of electrodes located at site 22 for connection to atrial tissue. The drug infusion lumen is located within this lead in this configuration and dispenses drugs at site 32 in the right atriurn. The 30 ventricular lead 72 carries a distal electrode 28 for both sensing and pacing. This composite lead configuration is well suited for the tre~tment of atrial fibrillation or atrial tachycardia.

WO 97/04834 ~ ) Ul 8 S~ PCT/US96/12279 Fig. 5 is a schematic block diagram of the IPD. The can 16 encloses a logic circuit 75 which is coupled to an energy source shown as a battery 39. The logicimplements conventional pacing therapies including AAI; AAT; VVI; DVI; VAT;
VDD; DDT and DDD mode pacing. These modalities are well understood and can be 5 realized without undue experiment~tion by one of ordinary skill in the art. For this reason they are not presented in more detail. The logic cilcuilly 75 is coupled to an atrial sense amplifier 17 and an atrial pulse generator 19 which are in turn coupled to the atrial lead system. The logic circuitry 75 is also coupled to a ventricular sense amplifier 21 and a ventricular pulse generator 23. If electrical defibrillation is desired the logic 75 10 can activate the high energy pulse generator 29. A switch network 31 which selects the a~plol.,;ate lead configuration for electrical defibrillation. It should be understood that additional electrodes not explicitly shown may be required to implement the electrical defibrillation therapy as is well known in this art. It should also be recognized that several electrode sites can be connected together to form an unitary electrode pole for 15 the delivery of defibrillation or cardioversion energies. When drug delivery is initiated by the logic the drug contained in the reservoir 38 is delivered through valve 33 to the lumen 35. It should be appreciated that the reservoir system may contain separate sections for two or more drugs. The ability to dispense plolll~tly after the declaration of an arrhythmia by logic 75 permits the use a sequence of drugs or a set of concurrently 20 delivered drugs to be used to treat an ~hyll~ ia.
Fig. 6 shows a representative signal 80 derived from the atrial sense amplifier 17 and a signal 81 from the ventricular amplifier 21 during normal sinus rhythm. The electrogra~n event generates atrial sense event 84 which occurs as a result of the detection of the atrial depolarization. Shortly the.c~l~l the ventricular sense amplifier 25 detects a ventricular depolarization as a sense event 85. In use the logic circuit 75 will have available to it the actual A-V conduction time as well as the atrial heart rate A-A
and the ventricular heart rate V-V and the V-A interval. This information can betabulated to form histograms and can be used to declare the existence of a treatable arrhythmia. Dissociation of the atrial and ventricular rhythms with acceleration or high 30 atria rate can be interpreted as a treatable atrial ~hy~llllia. Likewise a high ventricular rate or accelerating ventricular rate can be used to declare a treatable ventricular arrhythmia. Specific procedures for analyzing arrhythmias are well known in this art ~2()l~(l,'34 and depending on the drug and drug delivery site an ~pplopfiate therapeutic protocol can be developed. In each instance the device will declare a treatable arrhythmia by generating a control signal which will be used to invoke an electrical or drug based therapy.
Fig. 7 is a therapy decision tree indicating an illustrative hierarchy of therapy. It is preferred to monitor both the atrium and ventricles of the heart so that both the rhythm of each chamber and the relative timing of the atrial and ventricular events may be determin~(l The IPD may incorporate treatment algorithms which will invoke a more aggressive therapy in the event of a detectçd ventricular ~lhyLh~llia such as ventricular fibrillation than will be the case with a detected ~lhylhlllia such as atrial flutter. For example if the V-V interval is irregular and indicative of a high rate then electrical defibrillation may be invoked. Alternatively if the ventricular rate is relatively low or normal and the atrial rate is above a prede~ellllilled m~x;,..l.,,, the device may declare a treatable atrial arrhythmia, and invoke either a drug therapy or a pacing therapy or both.
15 As indicated by the flowchart the device monitors the heart for atrial arrhythmias in process 100. If no atrial allhy~ ia is detected the device monitors for a ventricular ~hy~llllia process 102. If no ventricular arrhythmia is detected then the device loops back into process 100. In this fashion the device can continuously monitor the heart for atrial or ventricular ~fllyllllllias. If however the process 100 indicates that an atrial 20 arrhythmia exists the device then check the ventricular state in process 104. If an atrial alfllylh,llia is present and a ventricular arrhythmia is not then the device selects a therapy from set 106. The choice between therapies as indicated by drug treatment modality 108 or pacing therapy modality 1 10 may be a physician selection duringdevice pro~ .."...il-g. It is expected that both drug delivery and a pacing regime may be 25 appr~,l,liate in some in.ct~nces With respect to the treatment of ventricular a~flly~l-llias, as set forth in set 111 it is expected that defibrillation shocks as indicated by treatment modality 1 12 will only be provided for declared ventricular fibrillation. Drug therapy as indicated by therapy modality 1 13 may be invoked in response to fibrillation or other ventricular tachy~fllyllllllias. Pacing therapies as shown in pacing modality 114 will be 30 used for other less sever ventricular tachyarythmia.
Fig. 8 shows the catheter 13 having an elongate body 132 with a peripheral surface 134. The catheter also has proximal end 136 and distal end 138, and a liquid WO 97/04834 2 ~ O O ~ i 4 PCT/US96/12279 lumen 140 extending longitudinally in the elongated body 132 from an inlet end at its proximal end 136 to an outlet port 142. First, second, and third eleckically conductive electrodes 144, 146, and 148 are ~tt~ch~cl on the peripheral surface 134 of the elongated body 132. The first electrode 144 is a tip electrode at the distal end 138, whereas the second and third electrodes 146 and 148 are semi-cylindrical electrodes partially encircling and disposed on opposite sides of the peripheral surface 134 of the elongated body 132 and on either side of the outlet port 142.
Alternatively, the outlet port 142 can be placed proximal to the third electrode148, or distal to the second electrode 146. The second and third electrodes 146 and 148 are spaced apart (i.e., in the range of 5 to 20 millimeters) and are spaced longitudinally along the peripheral surface 134 from the distal end 138 by distances (i.e., in the range of 11 to 16 centimeters) that afford positioning the catheter 13 in the heart with the first electrode 144 in the apex of its right ventricle chamber RV and the second and third electrodes in its right atrium chamber RA as is illustrated in Fig. 1, or with the second and third electrodes in the superior vena cava vein SVC of the heart that is connected with the right atrium chamber RA. Turning to Fig. 9, first, second, and third electrical leads 158, 160 and 162 extend longitudinally within the elongated body 132 to the first, second, and third electrodes 144, 146 and 148, respectively as seen in Fig. 8. The outlet port 142 is spaced longitudinally along the pel;l)hel~l surface 134 from the distal end 138 by distances (i.e., in the range of 5 to 25 centimeters, preferably at a distance of 12 centimeters) that, as illustrated, afford positioning the c~th~ter 13 in the heart with the first electrode 144 in the apex of the right ventricle chamber RV and the outlet port 142 in the right atrium chamber RA as illustrated in Fig. 1, or in the superior vena cava vein SVC that is conn~ctçcl with the right atrium chamber RA. As seen in Fig. 8 a value 164 on the elongate body 132 at the outlet port 142 allows liquid under pres~e in the liquid lumen 140 to exit through the outlet port 142 and to prevent movement of liquid or blood around the peripheral surface 134 of the elongated body 132 into the outlet port 142.
The proximal end 136 of the catheter 13 is releasably attached to the medical device 16 with the inlet opening of the liquid lumen 140 in colll,llullication with the outlet opening of the medical device 16.

Turning to Fig. 10, the valve 164 at the outlet port 142 is provided with a cylindrical band 198 of resiliently elastic material tensioned around and fixed to the elongated body 132 along one edge so that the cylindrical band 198 extends over the outlet port 142. The cylindrical band 198 is adapted to be resiliently flexed by pressure applied thought the liquid in the lumen 140 to afford movement of liquid through the outlet port 142 and between the elongated body 132 and the cylindrical band 198. The cylindrical band 198 may be constructed from a variety of rubber m~t~n~l ~ such as silicone rubber or polyurethane.
Drugs for treating the tissues of the heart with this device, include, but are not limited to, quinine, disopyramide, proc~ .llide, lidocaine, mexiletine, encainide, flecainide, propafenone, propanolol, nadolol, metrorolol, atenolol, amiodarone, sotalol, clofiliurn, dofetilide, ibutilide, veld~ lil, and diltiazem.
The catheter 13 (Fig. 8) is releasably ~tt~h~tl to and can be separated from themedical device 16 to facilitate inserting it into the heart of the human body. The catheter 13 is inserted into the heart transvenously through a cephalic or subclavian vein (not shown) to position its distal tip 38 at the apex of the right ventricle RV. The proximal end 136 ofthe catheter 13 is then ~tt~h~.~l to the medical device 16. The proximal end 136 of the c~th~ter 13 and a portion of the medical device 16 are adapted to seal together to thereby both engage the contact ends on the electrical leads 158, 160, and 162 (Fig. 9) with the electrical input connections of the medical device 16 and couple the inlet opening to the liquid lumen 140 in the ç~th~ter 13 with the outlet opening of the medical device 16.
The elongated body 132 ofthe catheter 13 (Fig. 8 and Fig. 9) can be made by extrusion of an implantable polyurethane, silicone rubber or other implantable flexible biocompatable polymer. The length of the elongated body 132 of the catheter 13 bet~,veen the proximal and distal ends 136 and 138 is preferably in the range of 55 to 100 centimeters. The electrical leads 158, 160, and 162 can be made of MP35N alloy. The electrodes 144, 146 and 148 (Fig. 11) can be made of implantable metal such as pl~tinllm/iridium alloys, or other commonly used electrode metal (e.g., stainless steel).
The catheter 13 has a stylet passageway 200 (Fig. 9) exten-ling longitudinally in the elongated body 132 from an inlet end (not shown) located at the proximal end 136 to 2200~4 the distal tip. The stylet passageway 200 is adapted to receive a guide stylet for stiffening and shaping the catheter 13 during insertion of the catheter 13 into the heart.
The lead includes means for securing the elongated body 132 within the heart 16. The elongated body 132 includes four circumferentially spaced tines 202 (Fig. 8) near the distal end 138 of the catheter 13 that project both radially away from the periphery ofthe elongated body 132 and toward its proximal end 136. The tines afford passive fixation of the distal end 138 in the apex of the right ventricle RV by eng~ging with the endocardial surface of the heart. Alternatively, the electrode 144 could include a helical cork-screw like projection adapted to be screwed into the tissue of the right ventricle by rotating the elongated body 132 after its insertion into the heart to anchor the catheter 13 in the heart tissues.
Referring now to figures 11 and 12 there is illustrated a second embodiment of acatheter 204 that can be used in an assembly of a medical device and catheter according to the present invention. The catheter 204 has portions that are similar in structure to the described above for the catheter 13, which portions have been identified by the sarne reference numerals to which have been added the suffix "a".
The catheter 204 (Fig. 11 and Fig. 12) has structural features and ~limen~ions similar to catheter 13 and functions in essçnti~lly the sarne manner. The catheter 204 includes an elongate body 132a having a peripheral surface 134a, proximal and distal ends 136a and 138a, and a liquid lumen 140a ~t~n-ling longitudinally in the elong~ted body 132a from an inlet end at its proximal end 136a to an outlet port and valve 164a between its proximal and distal ends 136a and 138a. Fig. 12 shows an alternativeconfiguration wherein the stylet passageway 200a forms a central lumen of the elongated body 132a and the electrical leads 160a and 158a are constructed of flexible wires which are arranged concentric with the central stylet passageway lumen 200a.
The liquid lumen is formed by adjacent arcuate passageways 140a. The second electrode 146a of the catheter 204 is spaced longitudinally along its peripheral surface 134a from its distal end 138a by distances in the range of 11 to 16 centimeters, to afford positioning the catheter 204 in the heart with the first electrode 144b (Fig. 11) in the apex of the right ventricle chamber and the second electrode 146a in the right atrium chamber or in a major vein (i.e., the superior vena cava) of the heart connected with the right atrium chamber. Sensing in the right atrium is unipolar between the electrode 146a 2 ~ ~ iJ ~fji (~ ~t and the can 16 of the medical device. Sensing in the right ventricle is unipolar between the electrode 144b and the can 16 of the medical device. Unipolar pacing electrical energy can be provided to the heart through the first electrode 144b.
Referring now to figures 13 and 14 there is illustrated a third embodiment of a S catheter 206 that can be used in an assembly of a medical device and catheter according to the present invention. The catheter 206 has portions that are similar in structure to those described above for the catheter 13, which portions have been identified by the same reference numerals to which have been added the suffix "b".
The catheter 206 has structural features and ~imen~ions similar to catheter 13 and functions es.s~nti~lly in the same manner. The catheter 206 includes an elongate body 132b having a peripheral surface 134b, proximal and distal ends 136b and 138b, and a liquid lumen 140b ext~nllin~ longitudinally in the elongated body 132b from an inlet end at its proximal end 136b to an outlet port and valve 164b between its proximal and distal ends 136b and 138b. The catheter 206 includes a fourth electrode 208 and electrical lead. The fourth electrode 208 is spaced longitudinally along the peripheral surface 134b from the distal end 138b by distances in the range of 5 to 20 millimeters, to afford positioning the catheter 206 in the heart with the first and fourth electrodes 144b and 208 in the apex of the right ventricle chamber and the second and thirdelectrodes 146b and 148b in the right atrium chamber or in a major vein. Sensing is bipolar between the electrodes 146b and 148b in the right atrium and bipolar between the electrodes 144b and 208 in the right ventricle. Bipolar or unipolar pacing electrical energy is provided to the heart through the first electrode 144b.
The present invention has now been described with reference to three embo-lim~nt~ thereof. It will be ~p~ent to those skilled in the art that many changes and modifications can be made in the embodiments described without departing from the scope ofthe present invention. For example electrodes 146, 148, and 208 may be cylindrical encircling the peripheral surface 134 of the elongated body 132.
Thus the scope of the present invention should not be limited to the structures described in this application, but only by structures described by the language of the claims and the equivalents of those structures.

Claims (9)

What is claimed is:

1. A catheter for use with a rhythm control device comprising:
an elongate body having a peripheral surface and having proximal and distal ends and having at least one liquid lumen extending longitudinally in said body from an inlet end at said proximal end to an outlet port between said proximal and distal ends;
first and second electrodes on said peripheral surface, said first electrode being at said distal end, said second electrode being spaced longitudinally along said peripheral surface from said distal end to afford positioning the catheter in the heart with said first electrode in the apex of the right ventricle chamber and said second electrode in one of the right atrium chamber or a major vein of the heart coupled to the right atrium chamber;
a first electrical lead extending longitudinally within said body from a contactend at said proximal end to said first electrode, and a second electrical lead extending longitudinally within said body from a contact end at said proximal end to said second electrode;
a valve on said body at said outlet port for affording movement of liquid under pressure in said liquid lumen out through said outlet port and for preventing movement of liquid around said peripheral surface into said outlet port; and connector means adapted for attaching the proximal end of said elongate body to the housing of a rhythm control device with said inlet opening of said liquid lumen in communication with the outlet port, the contact ends of said electrical leads in electrical connection with said connection means so that the rhythm control device receivessignals through said first, and second electrodes, and the electrical energy to the heart is provided through said first electrode.

2. A catheter according to claim 1 further including:
a third electrode on said peripheral surface;
a third electrical lead extending longitudinally within said body from a contactend at said proximal end to said third electrode;
said third electrode being spaced longitudinally along said peripheral surface from said first and second electrodes to afford positioning the catheter in the heart with said first electrode in the apex of the right ventricle chamber and said second and third electrodes in one of the right atrium chamber or a major vein of the heart connected to the right atrium chamber;
said contact ends of said electrical leads being adapted for electrical connection with said connection means so that the rhythm control device receives signals between said second and third electrodes.

3. A catheter according to claim 1 further including:
third and fourth electrodes on said peripheral surface and third and fourth electrical leads extending longitudinally within said body from contact ends at said proximal end to said third, and fourth electrodes, said third, and fourth electrodes being spaced longitudinally along said peripheral surface from each other and from said first and second electrodes to afford positioning said catheter in the heart with said first electrode in the apex of the right ventricle chamber;
said fourth electrode in the right ventricle chamber, and said second and third electrodes proximate the right atrium chamber adjacent a major vein of the heartconnected to the right atrium chamber;
said contact ends of said electrical leads being adapted for electrical connection with said connection means so that the electronic means receives signals from between said second and third electrodes and from between said first and fourth electrodes, and the electrical energy to the heart is provided through said first electrode or fourth electrode.

4. A catheter according to claim 1 wherein said outlet port of said liquid lumenopens through said peripheral surface at a position spaced longitudinally along said peripheral surface from said distal end of said body to afford positioning said catheter in the heart with said distal end of said body in the apex of the right ventricle chamber and said outlet port proximate said right atrium chamber adjacent a major vein of the heart connected to the right atrium chamber;
said valve means comprises an enclosure of resiliently elastic material tensioned around said periphery and fixed along said peripheral surface over said outlet port whereby said material is flexed by pressure applied through liquid in said lumen to dispense said liquid from said outlet port.

5. A catheter according to claim 1 wherein said electrodes are semi-annular and partially encircle the peripheral surface of the body.

6. An implantable medical device system for treating arrhythmia of a patient's heart comprising:
an atrial sense amplifier;
a ventricular sense amplifier;
logic coupled to said atrial sense amplifier and said ventricular sense amplifier for monitoring cardiac rhythm and for detecting and declaring an atrial arrhythmia, and for generating an arrhythmia detection signal;
a drug dispensing reservoir adapted for connection to a catheter lumen;
said drug dispensing reservoir contains a drug;
said drug dispensing reservoir for delivering said drug in response to said detection signal.

7. The device of claim 6 further comprising:
an atrial pulse generator;
said logic configured to provide atrial anti-tachyarrhythmia pacing in response to said detection signal.

8. The device of claim 6 further comprising:
a ventricular pulse generator;
said logic configured to provide ventricular anti-tachyarrhythmia pacing in response to said detection signal.

9. The device of claim 6 further comprising:
a ventricular pulse generator;
said logic configured to provide ventricular cardioversion in response to said detection signal.