EP0782467A1 - Implantable pharmacological defibrillator system - Google PatentsImplantable pharmacological defibrillator system
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- EP0782467A1 EP0782467A1 EP19960926775 EP96926775A EP0782467A1 EP 0782467 A1 EP0782467 A1 EP 0782467A1 EP 19960926775 EP19960926775 EP 19960926775 EP 96926775 A EP96926775 A EP 96926775A EP 0782467 A1 EP0782467 A1 EP 0782467A1
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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 pharmacological defibrillators are known from Cammelli, U.S. Patent No. 5,220,917. These devices have shown that the automatic delivery of drugs can be effective for the treatment of heart arrhythmia. However, the most appropriate techniques for sensing disease conditions and for invoking pharmacological 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 appropriate devices for delivery ofthe drug, which are addressed by this disclosure.
SUMMARY The present invention proposes both structures and methodologies for an implantable rhythm control device to supply pharmacological agents and electrical therapy in response to a detected arrhythmia. The implanted device may be used both for the treatment of atrial and ventricular arrhythmia, depending upon the choice ofthe 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 appropriate times to the heart tissue. The implanted device further includes a drug reservoir and associated pump system for delivery ofthe 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 ofthe heart. Higher energy defibrillation therapies are contemplated as well, and it is believed that cardioversion promptly after drug delivery may prove to be particularly effective. For the treatment of atrial arrhythmia, the device will dispense an anti¬ arrhythmic drug, either outside ofthe heart in the superior or inferior vena cava, or within the heart within either atrial or ventricular chambers. This drug will reach the 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 the coronary sinus which forms a part ofthe ventricular vasculature. Once again delivery may be timed to improve absorption ofthe drug by the tissue. Both the detection criteria for initiating the delivery ofthe drug or a pharmacological 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 arrythmia it is desirable but not absolutely necessary to have a relatively high energy cardioversion system which can provide higher current shocks to convert the arrhythmia should the drug therapy prove insufficient. A preferred catheter structure and dispensing valve are also disclosed. It is expected that lower energy cardioversion will be useful in conjunction with drug delivery.
BRIEF DESCRIPTION OF THE DRAWINGS An illustrative system is shown through the several figures ofthe drawing, wherein identical reference numerals indicate equivalent structures throughout: Fig. 1 is a schematic view ofthe overall system; Fig. 2 is a table which shows several classes ofthe implantable pharmacological defibrillator device;
Fig. 3 is a table which shows the locations of drug delivery for various arrhythmias;
Fig. 4 is a diagram depicting the geometry of several lead configurations for use with an implantable device;
Fig. 5 is a schematic block diagram ofthe implantable device; Fig. 6 shows a representative 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; 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 ofthe lead system may enter the superior vena cava (SCV), the coronary sinus (CS), the atria as indicated by the right atrium (RA), or the ventricles as indicated by the right ventricle
(RV). The can 16 ofthe 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 schematic diagram of Fig. I. A fully functioning IPD system would typically be a subset ofthe electrodes and drug delivery sites enumerated and disclosed in Fig. 1. Typically the IPD device will be targeted to a specific arrhythmia 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 a 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. Column 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 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 conduction time and V-A time interval are known. These sensed events permit relatively sophisticated algorithms to be used to ascertain the existence of an atrial arrhythmia and to distinguish atrial arrhythmia from ventricular arrhythmia. 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 necessary structures without undue experimentation. 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 ofthe device use this information to select an appropriate therapy.
Devices which include a ventricular pacing function such as device in class IV 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 arrhythmia pacing protocols including DDT mode and DDD mode, it is expected that the relatively simple WI 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 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. Fig. 3 is a table to depict illustrative locations for drug delivery sites for various anhythmias. 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 ofthe 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 tissues quickly after the onset of an arrhythmia. For this reason the sites shown in Fig. 3 are prefened but not necessarily required to treat the enumerated anhythmias. For example column number 51 conesponds to the delivery of a pharmacologic agent or drug into the right atrium from site 32 (Fig. 1). A less prefened location for drug delivery is indicated by column 50 which conesponds to site 30. It is believed that the 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 ofthe drug by the atrial tissue. In contrast to the optimal locations for atrial tachyarrhythmias the ventricular anhythmias are best treated by delivery ofthe drug into the coronary sinus at site 34 as indicated by column 55 and column 57. The coronary sinus forms the outlet for coronary circulation and retroperfusion may carry higher concentrations ofthe drug directly to the ventricular mass. A less prefened 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 with an IPD. These configurations are not intended to be an exhaustive list ofthe combinations and permutations taught in connection with Fig. 1 but rather represent several prefened mechanical configurations for atrial and ventricular applications. In the figure column 62 conesponds to the superior or inferior vena cava when the lead is implanted. Column 64 conesponds to the position ofthe lead with respect to the location ofthe coronary sinus. Column 68 conesponds to location ofthe right atrium while column 70 conesponds to the location ofthe right ventricle. Lead 60 is a configuration well suited to the treatment of atrial tachycardia or fibrillation. 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 ofthe lead 60 in the right atrium 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 ofthe 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 prefened 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 anhythmia. Once an anhythmia 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 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 lead fixation but that screw type fixation may be used as a less prefened 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 pacing an sensing the ventricular chamber. This configuration is especially well suited for the treatment of ventricular anhythmias.
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 atrium. The ventricular lead 72 carries a distal electrode 28 for both sensing and pacing. This composite lead configuration is well suited for the treatment of atrial fibrillation or atrial tachycardia. Fig. 5 is a schematic block diagram ofthe IPD. The can 16 encloses a logic circuit 75 which is coupled to an energy source shown as a battery 39. The logic implements conventional pacing therapies including AAI; AAT; WI; DVI; VAT; VDD; DDT and DDD mode pacing. These modalities are well understood and can be realized without undue experimentation by one of ordinary skill in the art. For this reason they are not presented in more detail. The logic circuitry 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 can activate the high energy pulse generator 29. A switch network 31 which selects the appropriate 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 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 promptly after the declaration of an arrhythmia by logic 75 permits the use a sequence of drugs or a set of concunently delivered drugs to be used to treat an anhythmia.
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 electrogram event generates atrial sense event 84 which occurs as a result ofthe detection ofthe atrial depolarization. Shortly thereafter the ventricular sense amplifier 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 be tabulated to form histograms and can be used to declare the existence of a treatable anhythmia. Dissociation ofthe atrial and ventricular rhythms with acceleration or high atria rate can be interpreted as a treatable atrial arrhythmia. Likewise a high ventricular rate or accelerating ventricular rate can be used to declare a treatable ventricular anhythmia. Specific procedures for analyzing anhythmias are well known in this art and depending on the drug and drug delivery site an appropriate 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 prefened to monitor both the atrium and ventricles ofthe heart so that both the rhythm of each chamber and the relative timing ofthe atrial and ventricular events may be determined. The IPD may incorporate treatment algorithms which will invoke a more aggressive therapy in the event of a detected ventricular arrhythmia such as ventricular fibrillation than will be the case with a detected arrhythmia such as atrial flutter. For example if the V-V interval is inegular 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 predetermined maximum the device may declare a treatable atrial anhythmia, and invoke either a drug therapy or a pacing therapy or both. As indicated by the flowchart the device monitors the heart for atrial arrhythmias in process 100. If no atrial arrhythmia is detected the device monitors for a ventricular anhythmia 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 anhythmias. If however the process 100 indicates that an atrial anhythmia exists the device then check the ventricular state in process 104. If an atrial anhythmia is present and a ventricular anhythmia 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 110 may be a physician selection during device programming. It is expected that both drug delivery and a pacing regime may be appropriate in some instances. With respect to the treatment of ventricular arrhythmias, as set forth in set 111 it is expected that defibrillation shocks as indicated by treatment modality 112 will only be provided for declared ventricular fibrillation. Drug therapy as indicated by therapy modality 113 may be invoked in response to fibrillation or other ventricular tachyarrhythmias. Pacing therapies as shown in pacing modality 114 will be 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 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 electrically conductive electrodes 144, 146, and 148 are attached on the peripheral surface 134 ofthe 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 ofthe peripheral surface 134 ofthe elongated body 132 and on either side ofthe outlet port 142.
Alternatively, the outlet port 142 can be placed proximal to the third electrode 148, 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 ofthe 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 peripheral 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 catheter 13 in the heart with the first electrode 144 in the apex ofthe 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 connected 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 pressure 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 ofthe elongated body 132 into the outlet port 142.
The proximal end 136 ofthe catheter 13 is releasably attached to the medical device 16 with the inlet opening ofthe liquid lumen 140 in communication with the outlet opening ofthe 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 materials such as silicone rubber or polyurethane.
Drugs for treating the tissues ofthe heart with this device, include, but are not limited to, quinine, disopyramide, procainamide, lidocaine, mexiletine, encainide, flecainide, propafenone, propanolol, nadolol, metrorolol, atenolol, amiodarone, sotalol, clofilium, dofetilide, ibutilide, verapamil, and diltiazem.
The catheter 13 (Fig. 8) is releasably attached to and can be separated from the medical device 16 to facilitate inserting it into the heart ofthe 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 ofthe right ventricle RV. The proximal end 136 ofthe catheter 13 is then attached to the medical device 16. The proximal end 136 ofthe catheter 13 and a portion ofthe 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 ofthe medical device 16 and couple the inlet opening to the liquid lumen 140 in the catheter 13 with the outlet opening ofthe 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 ofthe elongated body 132 ofthe catheter 13 between 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 platinum/iridium alloys, or other commonly used electrode metal (e.g., stainless steel). The catheter 13 has a stylet passageway 200 (Fig. 9) extending longitudinally in the elongated body 132 from an inlet end (not shown) located at the proximal end 136 to the distal tip. The stylet passageway 200 is adapted to receive a guide stylet for stiffening and shaping the catheter 13 during insertion ofthe 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 ofthe 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 ofthe distal end 138 in the apex ofthe right ventricle RV by engaging with the endocardial surface ofthe heart. Alternatively, the electrode 144 could include a helical cork-screw like projection adapted to be screwed into the tissue ofthe 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 a catheter 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 same reference numerals to which have been added the suffix "a".
The catheter 204 (Fig. 11 and Fig. 12) has structural features and dimensions similar to catheter 13 and functions in essentially the same 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 extending longitudinally in the elongated 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 alternative configuration wherein the stylet passageway 200a forms a central lumen ofthe elongated body 132a and the electrical leads 160a and 158a are constructed of flexible wires which are ananged concentric with the central stylet passageway lumen 200a. The liquid lumen is formed by adjacent arcuate passageways 140a. The second electrode 146a ofthe 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 positiomng the catheter 204 in the heart with the first electrode 144b (Fig. 11) in the apex ofthe right ventricle chamber and the second electrode 146a in the right atrium chamber or in a major vein (i.e., the superior vena cava) ofthe heart connected with the right atrium chamber. Sensing in the right atrium is unipolar between the electrode 146a and the can 16 ofthe medical device. Sensing in the right ventricle is unipolar between the electrode 144b and the can 16 ofthe medical device. Unipolar pacing electrical energy can be provided to the heart through the first electrode 144b.
Refening now to figures 13 and 14 there is illustrated a third embodiment of a 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 dimensions similar to catheter 13 and functions essentially 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 extending 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 ofthe right ventricle chamber and the second and third electrodes 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 embodiments thereof. It will be apparent 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 ofthe elongated body 132.
Thus the scope ofthe present invention should not be limited to the structures described in this application, but only by structures described by the language ofthe claims and the equivalents of those structures.
Priority Applications (7)
|Application Number||Priority Date||Filing Date||Title|
|US08639131 US5800498A (en)||1996-04-26||1996-04-26||Catheter for implantable rhythm control device|
|PCT/US1996/012279 WO1997004834A3 (en)||1995-07-25||1996-07-25||Implantable pharmacological defibrillator system|
|Publication Number||Publication Date|
|EP0782467A1 true true EP0782467A1 (en)||1997-07-09|
Family Applications (1)
|Application Number||Title||Priority Date||Filing Date|
|EP19960926775 Withdrawn EP0782467A1 (en)||1995-07-25||1996-07-25||Implantable pharmacological defibrillator system|
Country Status (3)
|EP (1)||EP0782467A1 (en)|
|JP (1)||JP2002515766A (en)|
|CA (1)||CA2200894A1 (en)|
Families Citing this family (1)
|Publication number||Priority date||Publication date||Assignee||Title|
|JP2012179333A (en) *||2011-02-28||2012-09-20||Ishikawa Toshie||Electrode|
Non-Patent Citations (1)
|See references of WO9704834A2 *|
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