US20060241732A1 - Catheter system for implanting an intravascular medical device - Google Patents

Abstract

A catheter system and method are employed to implant components of a medical device inside an animal. The catheter system includes a plurality of coaxial catheters and sheaths between which electrically interconnected components of the medical device are releasably held. A guide wire is inserted to a desired location inside the animal and the plurality of catheters and sheaths is slid as an assembly along the guide wire to that location. One of the sheaths is moved with respect to the other catheters and sheaths to release one of the components. The guide wire and the remaining catheters and sheaths are repositioned to a second location inside the animal and manipulated to release another component. Additional components can be implanted by further repositioning and manipulating steps. The catheter system is removed from the animal leaving the components in place.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This is a continuation in part of U.S. patent application Ser. No. 11/112,181 filed on Apr. 22, 2005.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
• Not Applicable
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to medical devices that are implanted into the vasculature of an animal, and more particularly to the apparatus for performing the implantation.
• 2. Description of the Related Art
• A remedy for people with slowed or disrupted natural heart activity is to implant a cardiac pacing device which is a small electronic apparatus that stimulates the heart to beat at regular rates.
• Typically the pacing device is implanted in the patient's chest and has sensor electrodes that detect electrical impulses associated with in the heart contractions. These sensed impulses are analyzed to determine when abnormal cardiac activity occurs, in which event a pulse generator is triggered to produce electrical pulses. Wires carry these pulses to electrodes placed adjacent specific cardiac muscles, which when electrically stimulated contract the heart chambers. It is important that the electrodes be properly located to produce contraction of the heart chambers.
• Modem cardiac pacing devices vary the stimulation to adapt the heart rate to the patient's level of activity, thereby mimicking the heart's natural activity. The pulse generator modifies that rate by tracking the activity of the sinus node of the heart or by responding to other sensor signals that indicate body motion or respiration rate.
• U.S. Pat. No. 6,445,953 describes a cardiac pacemaker that has a pacing device, which can be located outside the patient, to detect abnormal electrical cardiac activity. In that event, the pacing device emits a radio frequency signal, that is received by a stimulator implanted in a vein or artery of the patient's heart. Specifically, the radio frequency signal induces a voltage pulse in an antenna on the stimulator and that pulse is applied across a pair of electrodes, thereby stimulating adjacent muscles and contracting the heart.
• The stimulator in that wireless system is powered by the energy of the received signal thus requiring that the pacing device transmit a relatively strong radio frequency signal in order to provide adequate energy to the stimulator implanted deep in the patient's chest. It is desirable to place the stimulator, or at least the antenna for the stimulator, in a blood vessel located closer to the skin of the patient with electrodes implanted in one or more cardiac blood vessels and connected to the stimulator by wires extending through the electronic circuit circulatory system. This would enable more of the energy from the frequency signal to reach the stimulator, however, the blood vessels close to the skin are not sufficiently large to accommodate the size of the stimulator.
• The antenna, usually in the form of a coil, must possess several characteristics in order to function within the blood vessel. The coil must retain its shape in order to remain tuned to the particular radio frequency being used. The conductors of the antenna have to be insulated so that the blood and other substances flowing through the vascular system do not provide a short circuit or otherwise detune the antenna. In addition the antenna must be biologically compatible with the blood vessel walls and with the blood.
• Therefore, it is desirable to provide an apparatus for positioning each of the components of the medical device in the patient.
SUMMARY OF THE INVENTION
• A catheter system is provided to implant a medical device in an animal, wherein the medical device has a plurality of components that are to be placed at different locations. The system is particular adapted to implant a medical device in which the components are electrically interconnected by wires.
• The catheter system comprises a guide wire, a first catheter with a guide wire lumen for slidably receiving the guide wire, and a tubular outer sheath through which the first catheter extends. A first cavity is formed between the first catheter and the outer sheath within which a first component of the medical device is releasably located. A second cavity also is formed between the first catheter and the outer sheath within which a second component of the medical device is releasably located.
• In a preferred embodiment, the catheter system further includes a second catheter with a lumen within which the first catheter is slidably received. Thus, the first and second catheters are both within the outer sheath. The first cavity is located between the first and second catheters and the second cavity is located between the second catheter and the outer sheath. As an option, an inner sheath may be provided between the first and second catheters, with the first cavity between the first catheter and the inner sheath. More catheters and sheaths may be added coaxially on the catheter system to deliver additional components into the animal.
• The catheter system is manipulatable to independently release each of the first and second components at different locations in the animal. Initially the guide wire is inserted into the animal to a first location. Then, the assembly of catheters is slid over the guide wire until reaching the first location. The outer sheath is moved over the second catheter to expose the second component, that is deposited at the first location.
• If a desired second location for implantation of the second first component is along the existing route of the guide wire through the animal, the first and second catheters are slid along the guide wire to place the first component at the second location. Otherwise, the guide wire can be repositioned to the second location before the first and second catheters are slid into place. Thereafter, the first and second catheters are moved with respect to each other to expose the first component, which is deposited at the second location.
• A second embodiment of a catheter system having two guide wires and two catheter assemblies, one for each guide wire, also is described. The two catheter assemblies cooperate to implant a greater plurality of components, that are electrically interconnected by wires.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a representation of a cardiac pacing system attached to a medical patient;
• FIG. 2 is an isometric, cut-away view of a patient's blood vessels in which a receiver antenna, a stimulator and an electrode of an intravascular medical device have been implanted at different locations;
• FIG. 3 is a longitudinal cross sectional view through a distal end of a catheter system for implanting the components of the intravascular medical device;
• FIG. 4 is a transverse cross sectional view through a catheter system along line4-4 ofFIG. 3;
• FIG. 5 is a transverse cross sectional view through a catheter system along line5-5 ofFIG. 3;
• FIG. 6 is a transverse cross sectional view through a catheter system along line6-6 ofFIG. 3;
• FIGS. 7-14 depict a sequence of steps by which the components of the intravascular medical device are implanted in the patient; and
• FIGS. 15-25 illustrate an alternative sequence of steps by which the medical device components are implanted in a patient's vascular system.
DETAILED DESCRIPTION OF THE INVENTION
• Although the present invention is being described in the context of implanting components of a cardiac pacing system, it can be used to implant other types of medical devices into a patient's body. Furthermore, the present apparatus and method are not limited to implanting items in an animal's vascular system, but can be employed to implant elements elsewhere in the animal.
• Initially referring toFIG. 1, acardiac pacing system10 for electrically stimulating aheart12 to contract comprises anexternal power source14 and amedical device15 implanted in the circulatory system of a human medical patient. Themedical device15 receives a radio frequency (RF) signal from thepower source14 worn outside the patient and the implanted electrical circuitry is electrically powered from the energy of that signal. At appropriate times, themedical device15 delivers an electrical stimulation pulse into the surrounding tissue of the patient.
• Thepower source14 may be the same type as described in U.S. Pat. Nos. 6,445,953 and 6,907,285 and includes a radio frequency transmitter that is powered by a battery. The transmitter periodically emits a signal at a predefined radio frequency that is applied to a transmitter antenna in the form of a coil of wire within aband22 that is placed around the patient'supper arm23. In a basic version of thecardiac pacing system10, the radio frequency signal merely conveys energy for powering themedical device15 implanted in the patient. In other systems, the transmitter modulates the radio frequency signal with commands received from optional circuits that configure or control the operation of themedical device15.
• Referring toFIGS. 1 and 2, the exemplary implantedmedical device15 includes anintravascular stimulator16 located a vein orartery18 in close proximity to the heart. Because of its electrical circuitry, thestimulator16 is relatively large requiring a blood vessel that is larger than the arm vein, e.g. the basilic vein, which is approximately five millimeters in diameter. Therefore, thestimulator16 may be implanted in the superior or inferior vena cava. Electrical wires lead from thestimulator16 through the cardiac vascular system to one or more locations insmaller blood vessels19, e.g. the coronary sinus vein, at which stimulation of the heart is desired. At such locations, theelectrical wire25 are connected to aremote electrode21 secured to the blood vessel wall.
• Because thestimulator16 of themedical device15 is near the heart and relatively deep in the chest of the human medical patient, areceiver antenna24 for the RF signal is implanted in a vein orartery26 of the patient's upperright arm23 at a location surrounded by the transmitter antenna within thearm band22. That arm vein orartery26 is significantly closer to the skin and thusreceiver antenna24 picks up a greater amount of the energy of the radio frequency signal emitted by thepower source14, than if the receiver antenna was located on thestimulator16. Alternatively, another limb, neck or other area of the body with an adequately sized blood vessel close to the skin surface of the patient can be used. Thereceiver antenna24 is connected to thestimulator16 by amicro-coaxial cable34.
• As illustrated inFIG. 2, theintravascular stimulator16 has abody30 constructed similar to well-known expandable vascular stents. Thestimulator body30 comprises a plurality of wires formed to have a memory defining a tubular shape or envelope. Those wires may be heat-treated platinum, Nitinol, a Nitinol alloy wire, stainless steel, plastic wires or other materials. Plastic or substantially nonmetallic wires may be loaded with a radiopaque substance which provide visibility with conventional fluoroscopy. Thestimulator body30 has a memory so that it normally assumes an expanded configuration when unconfined, but is capable of assuming a collapsed configuration when disposed and confined within a catheter assembly, as will be described. In that collapsed state, thetubular body30 has a relatively small diameter enabling it to pass freely through the vasculature of a patient. After being properly positioned in the desired blood vessel, thebody30 is released from the catheter and expands to engage the blood vessel wall. Thestimulator body30 and other components of themedical device15 are implanted in the patient's circulatory system using a novel technique that employs a unique catheter system described hereinafter.
• Thebody30 has astimulation circuit32 mounted thereon and, depending upon its proximity to theheart12, may hold afirst electrode20 in the form of a ring that encircles the body. Alternatively, when thestimulator16 is relatively far from theheart12, thefirst electrode20 can be remotely located in a small cardiac blood vessel much the same as asecond electrode21. Thestimulation circuit32, which may be the same type as described in the aforementioned U.S. patents, includes a power supply to which themicro-coaxial cable34 from thereceiver antenna24 is connected. The power supply utilizes electricity from that antenna to charge a storage capacitor that provides electrical power to the stimulation circuit. A conventional control circuit within thestimulation circuit32 detects the electrical activity of the heart and determines when electrical pulses need to be applied so that theheart12 contracts at the proper rate. When stimulation is desired, thestimulation circuit32 applies electrical voltage from its internal storage capacitor across theelectrodes20 and21. Thesecond electrode21 and the first electrode when located remotely from thestimulator16, can be mounted on a collapsible body of the same type as thestimulator body30.
• With reference toFIG. 3, the components of themedical device15 are inserted into the patient utilizing acatheter system50 which is a meter or more long as is necessary to extend from an incision in the patient through the vascular system to the various locations where the components of themedical device15 are to be implanted. Thecatheter system50 has a proximal end that remains outside the patient to which the physician has access to manipulate the elements of the catheter system, and has a distal end that is inserted into the patient and which contains the medical device components.
• The distal end section of thecatheter system50 is illustrated inFIG. 3 to which continuing reference is made. The catheter system comprises aconventional guide wire52 over which anassembly51 of several catheters and sheaths are coaxially inserted. Those catheters and sheaths are made of a flexible biologically compatible material commonly used for medical catheters. A first, or inner,catheter54 has a tubular construction with alumen55 through which theguide wire52 extends, see also the cross-section through this region of thecatheter system50 inFIG. 4. A first component, such as thesecond electrode21, of the medical device is positioned around the end of thefirst catheter54 with a firstinner sheath56 around the first component to maintain it in a collapsed state. Afirst cavity57 is formed between thefirst catheter54 and the firstinner sheath56 within which the first component is located. The firstinner sheath56 extends longitudinally to the proximal end of thefirst catheter54 which is outside the patient. Both thefirst catheter54 and the firstinner sheath56 have a distal end that is spaced from thedistal end53 ofcatheter assembly51.
• A second, or intermediate,catheter58 extends longitudinally over the firstinner sheath56 so that the inner components of thecatheter system50 described thus far are located within alumen60 of thesecond catheter58, see also the cross-section through this region inFIG. 5. The end of the second catheter projects beyond the end of the first catheter, but falls short of thedistal end53 of thecatheter assembly51. Theantenna40, which also is referred to herein as a second component of themedical device15, is placed around the end section of thesecond catheter58 and is held in an elongated, reduced diameter state by a secondinner sheath62 that extends around theantenna40 and along thesecond catheter58 to the proximal end of thecatheter system50. Asecond cavity63 is defined between thesecond catheter58 and the secondinner sheath62 within which the second medical device component is located.
• With reference toFIGS. 3 and 6, athird catheter64 is located around and extends along the outside of the secondinner sheath62 and projects to substantially thedistal end53 of thecatheter assembly51. A third component, in this case thestimulator16, is located around thethird catheter64 and is held in its collapsed state by a third, or outer,sheath66 that forms the outermost element of thecatheter system50 extending around all of the other elements. Athird cavity65 is located between thethird catheter64 and thethird sheath66 within which thestimulator16 is located. Theelectrical wire25 extends from thestimulator16 through thecatheter system50 to the first component,electrode21, and themicro-coaxial cable34 extends from thestimulator16 to thesecond component40. More coaxially arranged catheters and sheaths can be provided to deliver additional components of a medical device.
• Themedical device15 is implanted in the vascular system of the patient by first inserting theguide wire52 as depicted inFIG. 7. An incision is made into large blood vessel in the patient's thigh, for example, using conventional surgical procedures for inserting catheters. Theguide wire52 is then threaded through the vasculature until its distal end reaches the location at which thestimulator16 is to be implanted. Next, thecatheter assembly51 is inserted over the proximal end of theguide wire52 and pushed there along to the location selected for the stimulator implantation, as shown inFIG. 8. With thestimulator16 properly positioned within theblood vessel18, the outer, orthird sheath66 is pulled out of the patient while maintaining the remainder of thecatheter system50 in place. Once thethird sheath66 clears thestimulator16, the stimulator'sbody30 expands diametrically against the wall of theblood vessel18 thereby securing thestimulator16 in place, as illustrated inFIG. 9. This diametric expansion of thestimulator body30 causes a longitudinal contraction as evident from a comparison of the length of thestimulator16 inFIGS. 8 and 9. It should be noted that before thethird sheath66 fully exposes thestimulator body30, that sheath can be pushed back into the patient over thethird catheter64 and the exposed portion of thestimulator16. This action re-collapses thestimulator body30 so that it may be repositioned within theblood vessel18.
• With reference toFIG. 10, after implanting thestimulator16, theguide wire52 is advanced through the vascular system until it reaching a point at which theantenna40 is desired to be placed inblood vessel26. Thereafter, the remainder of thecatheter assembly51 is advanced along theguide wire52 until thedistal end53 reaches the desired location (as seen asFIG. 3). As this advancement occurs, themicro-coaxial cable34 connecting theantenna40 to thestimulator16 is unfurled from catheter assembly. Next, the physician withdraws the secondinner sheath62 from the patient. When the secondinner sheath62 has been withdrawn sufficiently to expose theantenna40, that component contracts longitudinally and expands diametrically against the inner surface of theblood vessel26. That action secures theantenna40 in place, as shown inFIG. 11. Before theantenna40 has been fully exposed, the secondinner sheath62 may be pushed back into the patient to re-collapse the partially expanded antenna, if necessary.
• With theantenna40 secured in place, the physician extracts the remainder of thecatheter system50, including theguide wire52 from theblood vessel26 to a junction where the assembly can be directed into theother blood vessel19 for implantation of thesecond electrode21. From that withdrawn position, theguide wire52 alone is advanced through the vascular system until its distal end reaches the location withinblood vessel19 at which the electrode is to be implanted. Then, the remainder of thecatheter assembly51 is advanced along theguide wire52 until itsdistal end53 reaches the distal end of the guide wire, as depicted inFIG. 12. At this point, the first, or inner,catheter54 and its surroundingsheath56 are located at the distal end of the guide wire along with thesecond electrode21. With that electrode properly positioned within theblood vessel19, thefirst sheath56 is withdrawn from the patient along thefirst catheter54. Upon being exposed, thesecond electrode21 expands to engage the wall of theblood vessel19, thereby being secured in place as illustrated inFIG. 13. Other techniques for securing the electrode and the other components in the blood vessel wall may be employed. Then, thefirst catheter54 andguide wire52 are withdrawn from the vascular system of the patient leaving the components of themedical device15 in place, as shown inFIG. 14.
• Thefirst catheter system50 employs asingle catheter assembly51 that comprises coaxially located catheters and sheaths to carry the components of themedical device15.FIGS. 15-22 illustrate asecond catheter system70 having first andsecond catheter assemblies71 and72, which are inserted through the vascular system of the patient. Thesecatheter assemblies71 and72 are structurally each similar to thecatheter assembly51 previously described. Thefirst catheter assembly71 is used to deliver thestimulator16 and theantenna40, and thesecond catheter assembly72 delivers a pair ofelectrodes87 and90 to different locations in the patient's vasculature. The implantation procedure commences by inserting afirst guide wire74 into the patient and threading it through the vascular system until reaching aposition75 inblood vessel26 at which theantenna40 is to be located as shown inFIG. 15. Asecond guide wire76 also is inserted through the vascular system to alocation77 inblood vessel19 for one of the electrodes. Then thefirst catheter assembly71 is placed over thefirst guide wire74 and thesecond catheter assembly72 is placed over thesecond guide wire76. The two catheter assemblies are slid in unison over their respective guide wires until thefirst catheter assembly71 reaches thelocation79 inblood vessel18 for thestimulator16 as illustrated inFIG. 16. The twocatheter assemblies71 and72 have to be inserted simultaneously into the patient because the components carried by them are connected by relatively short electrical wires. Alternatively those interconnecting wires may be long enough to extend outside the patient while only some of the components have been implanted. This eliminates the need to simultaneously insert bothcatheter assemblies71 and72 and also permits testing of each component upon being finally positioned in the vascular system. For example, theantenna40 can be tested for adequate signal reception before implanting thestimulator16.
• Thefirst catheter assembly71 has afirst catheter78 with asecond catheter80 extending coaxially there around. Specifically, thefirst catheter78 has a lumen through which thefirst guide wire74 passes and thesecond catheter80 has another lumen within which the first catheter is received. A first cavity is formed between those catheters within which theantenna40 is located. In thesecond catheter system70, there is no inner sheath between the antenna and thesecond catheter80, however such a sheath could be provided as in the previously describedcatheter system50. A firstouter sheath82 extends longitudinally along and around thesecond catheter80 forming a second cavity there between within which thestimulator16 is located adjacent the distal end of thefirst catheter assembly71.
• Thesecond catheter assembly72 has athird catheter84 immediately surrounding thesecond guide wire76. Afourth catheter86 extends coaxially around and along thethird catheter84 forming a cavity there between within which afirst electrode87 is located. In particular, thethird catheter84 has a lumen through which thesecond guide wire76 passes and thefourth catheter86 has another lumen within which the third catheter is received. A secondouter sheath88 extends coaxially around and along thefourth catheter86 forming a cavity there between within which asecond electrode90 is held.
• With reference toFIG. 17, while thefirst catheter assembly71 is held in place, thesecond catheter assembly72 is advanced along thesecond guide wire76 past the end of thefirst catheter assembly71 and into theblood vessel19. As this advancement occurs, the electrical wires connecting the first andsecond electrodes87 and90 to thestimulator16 are pulled along and unfurled from the distal end of thesecond catheter assembly72. Thesecond catheter assembly72 continues slide over thesecond guide wire76 until reaching the location desired for implantation of thesecond electrode90. Then the secondouter sheath88 is withdrawn from the patient by sliding it along the remaining components of thesecond catheter assembly72. That action exposes thesecond electrode90 which thereby expands diametrically to become imbedded in the inner wall of theblood vessel19, as shown inFIG. 18. Other techniques for securing the electrode in the blood vessel wall may be employed.
• Then the third andfourth catheters84 and86 are withdrawn partially from the patient carrying thefirst electrode87 through theblood vessel19 until it is located at the desired place for implantation, as depicted inFIG. 19. If the desired location for thefirst electrode87 is not along the existing route of thesecond guide wire76, that guide wire may also be partially extracted from the patient and reinserted through a different route to the desired implantation point. In that latter case, the twocatheters84 and86 then are slid along thesecond guide wire76 until thefirst electrode87 reaches that desired point of implantation. When the first electrode is properly positioned, thethird catheter84 is withdrawn from the patient so its distal end slides over thefirst electrode87. Upon being fully exposed, thefirst electrode87 expands diametrically thereby engaging the walls of theblood vessel19 becoming secured in place as illustrated inFIG. 20. Here too, other techniques may be used to secure this electrode in the blood vessel wall. Thereafter, thethird catheter84 and thesecond guide wire76 are withdrawn from the patient leaving the twoelectrodes87 and90 in place, as shown inFIG. 21.
• Then with thefirst catheter assembly71 still positioned at the location desired for thestimulator16, the firstouter sheath82 of thefirst catheter assembly71 is withdrawn from the patient to release the stimulator. When thebody30 of the stimulator is fully exposed, it expands diametrically against the inner wall of theblood vessel18 to secure thestimulator16 in place, as depicted inFIG. 22. Next, the first andsecond catheters78 and80 are advanced along thefirst guide wire74, through the now expandedstimulator body30, until the collapsedantenna40 carried by those catheters is located within theblood vessel26 at the desired position for implantation shown inFIG. 23. At this time, thesecond catheter80 is pulled at least partially from of the patient to expose theantenna40 thereby allowing the antenna coil to expand against the inner wall of theblood vessel26 as exemplified inFIG. 24. Then, thefirst catheter78 and thefirst guide wire74 are removed from the patient, either separately or in unison. This leaves themedical device15, comprising thestimulator16,antenna40 and the first andsecond electrodes87 and90, implanted in the patient's vasculature as shown inFIG. 25.
• The foregoing description was primarily directed to preferred embodiments of the invention. Even though some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. For example, different quantities of components for the medical device can be implanted by modifying the catheter assembly with more catheters and sheaths, and the position of the components on the catheter assembly can be changed to enable a different order of implantation. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.

Claims (37)

1. A catheter system for implanting a medical device in an animal, wherein the medical device has a plurality of components for implantation at different locations, said catheter system comprising:

a guide wire;

an inner catheter with a guide wire lumen within which the guide wire is slidably receivable; and

a tubular outer sheath through which the inner catheter extends, wherein a first component and a second component of the medical device being releasably located between the inner catheter and the outer sheath with an electrically conductive wire connected to both the first and second components;

wherein the catheter system is manipulable to independently release each of the first component and the second component at different locations in the animal.

2. The catheter system as recited inclaim 1 further comprising:

first cavity formed between the inner catheter and the outer sheath within which a first component of the medical device is releasably located;

and a second cavity formed between the inner catheter and the outer sheath within which a second component of the medical device is releasably located, wherein the electrically conductive wire extends between the first and second cavities;

and a member separating the first and second cavities.

3. The catheter system as recited inclaim 1 wherein the tubular outer sheath is slidable with respect to the inner catheter to release the first component into the animal.

4. The catheter system as recited inclaim 1 further comprising an intermediate catheter extending within the tubular outer sheath and having a lumen within which the inner catheter extends.

5. The catheter system as recited inclaim 4 wherein the intermediate catheter and the inner catheter are slidable with respect to each other to release the second component into the animal.

6. A catheter system for implanting a medical device in an animal, wherein the medical device has a plurality of components that are electrically interconnected, said catheter system comprising:

a first guide wire;

a first catheter with a first lumen extending along a longitudinal axis and within which the first guide wire is slidably receivable;

a second catheter with a second lumen in which the first catheter is slidably received, wherein a first cavity is defined between the first and second catheters;

a first component of the medical device releasably located in the first cavity;

a tubular first outer sheath through which the second catheter slidably extends, wherein a second cavity is defined between the second catheter and the first outer sheath; and

a second component of the medical device releasably located in the second cavity.

7. The catheter system as recited inclaim 6 wherein the tubular first outer sheath is slidable with respect to the second catheter to release the second component into the animal.

8. The catheter system as recited inclaim 6 wherein the second catheter is slidable with respect to the first catheter to release the first component into the animal.

9. The catheter system as recited inclaim 6 further comprising a first inner sheath between the first and second catheters with the first component located between the first inner sheath and the first catheter.

10. The catheter system as recited inclaim 6 wherein the first component is one of a stimulation circuit, an antenna, and an electrode, and the second component is another one of a stimulation circuit, an antenna, and an electrode.

11. The catheter system as recited inclaim 6 wherein at least one of the first component and the second component comprises an expandable body that is held in a collapsed state in the catheter system and which expands upon being released from the catheter system.

12. The catheter system as recited inclaim 6 wherein the first component and the second component are located in tandem along the longitudinal axis.

13. The catheter system as recited inclaim 6 further comprising:

a third catheter within the first outer sheath and having a third lumen through which the second catheter is slidably received, wherein the second cavity is formed between the second and third catheters and a third cavity is formed between the third catheter and the first outer sheath; and

a third component of the medical device releasably located in the third cavity.

14. The catheter system as recited inclaim 13 further comprising:

a first inner sheath extending between the first and second catheters with the first component located between the first inner sheath and the first catheter; and

a second inner sheath extending between the second and third catheters with the second component located between the second inner sheath and the second catheter.

15. The catheter system as recited inclaim 6 further comprising;

a second guide wire;

a third catheter with a third lumen within which the second guide wire is slidably receivable;

a second outer sheath through which the third catheter slidably extends, wherein a third cavity is defined between the third catheter and the second outer sheath; and

a third component of the medical device releasably located in the third cavity and electrically connected by a wire to one of the first and second components.

16. The catheter system as recited inclaim 6 further comprising;

a second guide wire;

a third catheter with a third lumen in which the second guide wire is slidably receivable;

a fourth catheter with a fourth lumen in which the third catheter is slidably received, wherein a third cavity is defined between the third and fourth catheters;

a third component of the medical device releasably located in the third cavity;

a tubular second outer sheath through which the fourth catheter slidably extends, wherein a fourth cavity is defined between the fourth catheter and the second outer sheath; and

a fourth component of the medical device releasably located in the second cavity;

wherein at least one of the third component and the fourth component is electrically connected by a wire to one of the first component and the second component.

17. The catheter system as recited inclaim 16 further comprising an inner sheath extending between the third and fourth catheters with the third component located between the inner sheath and the third catheter.

18. A method of implanting a medical device in an animal, wherein the medical device has a plurality of components, said method comprising:

inserting a first guide wire to a first location inside the animal;

inserting a first catheter assembly releasably containing a first component and a second component of the medical device over the first guide wire until the first catheter assembly reaches the first location, wherein the first component and the second component are electrically connected;

releasing one of the first component and the second component at the first location inside the animal;

repositioning the first catheter assembly to a second location inside the animal; and

releasing another one of the first component and the second component at the second location inside the animal.

19. The method as recited inclaim 18 wherein inserting a first catheter assembly comprises employs a first catheter assembly that comprises a first catheter with a first lumen within which the first guide wire is received, and a tubular first outer sheath through which the first catheter extends, a first cavity defined between the first catheter and the first outer sheath and releasably containing a first component of the medical device, and a second cavity defined between the first catheter and the first outer sheath and releasably containing a second component of the medical device.

20. The method as recited inclaim 19 wherein repositioning the first catheter assembly comprises relocating the first guide wire adjacent the second location.

21. The method recited inclaim 19 further comprising removing the first catheter assembly from the animal leaving the first and second components inside the animal.

22. The method as recited inclaim 19 wherein the first catheter assembly further comprises a second catheter within the first outer sheath and having a second lumen within which the first catheter is slidably received, wherein the first cavity is defined between the first and second catheters and the second cavity is defined between the second catheter and the first outer sheath.

23. The method as recited inclaim 22 wherein repositioning the first catheter assembly comprises relocating the first guide wire adjacent the second location.

24. The method as recited inclaim 23 wherein repositioning the first catheter assembly further comprises sliding at least one of the first and second catheters along the first guide wire to the second location.

25. The method as recited inclaim 22 wherein releasing one of the first component and the second component comprises sliding the first outer sheath and the second catheter with respect to each other.

26. The method as recited inclaim 22 wherein releasing another one of the first component and the second component comprises sliding the first catheter and the second catheter with respect to each other.

27. The method as recited inclaim 22 wherein the first catheter assembly further comprises an inner sheath extending between the first and second catheters; and wherein releasing another one of the first component and the second component comprises sliding the inner sheath and the first catheter with respect to each other.

28. The method as recited inclaim 22 further comprising:

inserting a second guide wire to a third location inside the animal;

inserting a second catheter assembly over the second guide wire until the second catheter assembly reaches the third location, wherein the second catheter assembly comprises a third catheter with a third lumen in which the second guide wire is slidably received, and a tubular second outer sheath through which the third catheter slidably extends, wherein a third cavity is defined between the third catheter and the second outer sheath and releasably contains a third component that is electrically connected by a wire to one of the first and second components; and

releasing the third component inside the animal.

29. The method as recited inclaim 28 wherein inserting a first catheter assembly and inserting a second catheter assembly are performed in unison.

30. The method as recited inclaim 28 wherein releasing the third component comprises sliding the second outer sheath and the third catheter with respect to each other.

31. The method as recited inclaim 28 further comprising removing the second catheter assembly from the animal while leaving the third component inside the animal.

32. The method as recited inclaim 22 further comprising:

inserting a second guide wire to a third location inside the animal;

inserting a second catheter assembly over the second guide wire until the second catheter assembly reaches the third location, wherein the second catheter assembly comprises a third catheter with a third lumen in which the second guide wire is slidably received, a fourth catheter with a fourth lumen within which the third catheter is slidably received, a third cavity defined between the third and fourth catheters and releasably containing a third component of the medical device, a tubular second outer sheath through which the fourth catheter slidably extends, and a fourth cavity defined between the fourth catheter and the second outer sheath and releasably containing a fourth component of the medical device, wherein at least one of the third and fourth components is electrically connected by a wire to one of the first and second components;

releasing one of the third component and the fourth component inside the animal;

repositioning the second catheter assembly to a fourth location in the animal; and

releasing another one of the third component and the fourth component inside the animal.

33. The method as recited inclaim 32 wherein inserting a first catheter assembly and inserting a second catheter assembly are performed in unison.

34. The method as recited inclaim 32 wherein repositioning the second catheter assembly comprises:

moving the second guide wire adjacent the fourth location; and

sliding at least one of the third and fourth catheters along the second guide wire to the fourth location.

35. The method as recited inclaim 32 wherein releasing one of the third component and the fourth component comprises sliding the second outer sheath and the fourth catheter with respect to each other.

36. The method as recited inclaim 32 wherein releasing another one of the third component and the fourth component comprises sliding the third catheter and the fourth catheter with respect to each other.

37. The method as recited inclaim 32 wherein the second catheter assembly further comprises an inner sheath extending between the third and fourth catheters; and wherein releasing another one of the third component and the fourth component comprises sliding the inner sheath and the third catheter with respect to each other.

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