Endoluminal implant with locking and centering fixation system

An implant centering system includes a sensor connected to a hollow cylindrical anchor via at least two struts. The hollow cylindrical anchor is transformable between a radially compressed configuration for delivery and a radially expanded configuration for lodging against a vessel wall. The struts longitudinally relocate the sensor between a first position in which the sensor is longitudinally spaced apart from the radially compressed anchor, and a second position in which the sensor is at least partially within a lumen of the radially expanded anchor and radially centered within vessel. In one embodiment, the struts are heat-set into a curved configuration and an externally applied force longitudinally relocates the sensor until the struts lock over center into their heat-set configuration. In another embodiment, radial expansion of the anchor longitudinally relocates the sensor without an externally applied force.

FIELD OF THE INVENTION

The invention relates to a medical device for endoluminal implantation within a patient's vessel. A fixation system is provided for centering and locking the implant within the vessel. The medical device may be a leadless sensor.

BACKGROUND OF THE INVENTION

Medical implants such as leadless sensors or other apparatuses may be delivered via catheter and implanted within a vessel or vasculature. In cases where the target site for implantation is reached through an extended and sometimes tortuous route, the implant preferably has, or can be temporarily compacted to have a small delivery profile or configuration. One major vessel of interest for locating a leadless sensor is the main pulmonary artery and its branches. The right pulmonary artery is a particularly challenging location in which to endoluminally deliver a leadless sensor or other apparatus because navigation of the multiple 180° bends to reach the right pulmonary artery from a femoral vein access site is very difficult. Specifically, one exemplary vascular path includes inserting a delivery catheter into a femoral vein, tracking the catheter to the inferior vena cava, into the right atrium, through the tricuspid valve into the right ventricle, and through the pulmonary valve to access the pulmonary trunk, then selectively entering the right pulmonary artery.

Once the delivery device reaches the target implantation site, a reliable means of fixation must be deployed to secure the sensor within the vessel. It is desirable to secure the sensor radially centered within the vessel, with little or no contact with the vessel wall, in order to avoid tissue ingrowth and obtain accurate sensor measurements. Particularly within blood vessels, the sensor is subjected to a continuous pulsatile fluid flow. The potential of detachment of a sensor from the implantation site represents a serious and possibly life-threatening event. Thus, secure fixation of leadless implants is important for successful operation of the implant as well as safety of the patient.

Accordingly, it is an object of the present invention to provide a fixation device or system that has a minimized delivery profile and that deploys to secure a sensor radially centered within the vessel.

BRIEF SUMMARY OF THE INVENTION

Embodiments hereof relate to a medical implant including a sensor connected to a hollow cylindrical anchoring component, hereinafter referred to as an anchor. The anchor is transformable between a radially compressed configuration for delivery within a vasculature and a radially expanded configuration for lodging against a vessel wall. At least two struts each have a first end attached to the sensor and a second end attached to the anchor. The struts may operate to longitudinally relocate the sensor between a first position in which the sensor is longitudinally spaced apart from the radially compressed anchor, and a second position in which at least a portion of the sensor is located and centered within a lumen of the radially expanded anchor. In one embodiment, the struts are locked in an over-center configuration wherein the first ends of the struts longitudinally have passed the second ends of the struts.

In an embodiment, a method of radially centering a sensor within a vessel includes percutaneously introducing an implant comprising a sensor that is connected to a hollow cylindrical anchor by at least two struts. In an initial delivery configuration, the sensor is longitudinally spaced apart from the anchor. The implant is advanced through the vasculature to an implantation site, and the anchor is radially expanded to lodge against a vessel wall at the implantation site. A force is then applied to transform the implant into a deployed configuration by longitudinally relocating the sensor to a position in which at least a portion of the sensor is located and centered within a lumen of the radially expanded anchor. The struts are locked in an over-center configuration.

Another method of radially centering a sensor within a vessel includes percutaneously introducing an implant comprising a sensor that is spaced apart from and connected to a hollow cylindrical anchor via at least two struts. The sensor is advanced through the vasculature to an implantation site, and the anchor is radially expanded to lodge against a vessel wall at the implantation site. The action of radially expanding anchor longitudinally relocates the sensor via the struts to a position in which at least a portion of the sensor is located and centered within a lumen of the radially expanded anchor.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The terms “distal” and “proximal” are used in the following description with respect to a position or direction relative to the treating clinician. “Distal” or “distally” are a position distant from or in a direction away from the clinician. “Proximal” and “proximally” are a position near or in a direction toward the clinician.

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Although the description of the invention is in the context of treatment of blood vessels such as the coronary, carotid and renal arteries, the invention may also be used in any other body passageways where it is deemed useful. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

Embodiments hereof relate to an implant100including a leadless sensor102and a fixation system for locking and radially centering the sensor within vasculature such as a blood vessel. Implant100comprises an anchor106for radially centering and securing a leadless sensor102in a vessel. In one embodiment, sensor102is an active leadless pressure sensor. An exemplary leadless sensor that may be adapted for use in embodiments hereof is of the type described U.S. Pat. No. 7,572,228 to Wolinsky et al. An active leadless pressure sensor system implanted within the body may be designed to continuously monitor blood pressure, allowing physicians to proactively administer medications so that patients avoid dangerous blood pressure spikes. For purposes of describing the invention hereof only the basic structure of sensor102is described herein. Generally, sensor102has a capsule-shaped housing that hermetically encloses the sensor's electrical components, including a wireless communication system and an internal power source. The sensors described herein are sized to be delivered endoluminally within delivery systems hereof tracked through the vasculature from a percutaneous entry site such as a femoral, jugular or subclavian vein or artery, and may have an outer diameter between 16-18 French (5.3-6 mm). In accordance with embodiments hereof, the sensor102described herein may be delivered through the vasculature to be implanted in either the left or right pulmonary artery. In other embodiments, medical implants described herein may be implanted within other blood vessels such as the aorta, renal arteries, or inferior or superior vena cava. Although medical implants described herein are described as leadless pressure sensors, in other embodiments hereof delivery and fixation systems and methods herein may be used to deliver and implant other medical devices that are configured to be secured within blood vessels, such as another type of sensor device or a stimulator device, which may or may not be “leadless” or self-contained.

Sensor102is connected to an anchor106via at least struts104A,104B. As will be explained in more detail below, anchor106is a radially-expandable hollow cylindrical structure that is configured to lodge against a vessel wall when expanded in situ. Struts104A,104B have first ends108A,108B, respectively, connected to a distal end of sensor102and second ends110A,110B, respectively, connected to a proximal end of anchor106. Although not required, in one embodiment, second ends110A,110B of struts104A,104B are positioned at diametrically opposite locations on the proximal end circumference of anchor106. Although shown with only two struts104A,104B connecting sensor102to anchor106, it will be apparent to those of ordinary skill in the art that implant centering fixation implant100may include three or more struts that may be attached at equally-spaced locations on the proximal end circumference of anchor106. Struts104A,104B operate to longitudinally relocate sensor102between an initial or delivery configuration shown inFIG. 1in which sensor102is longitudinally spaced apart from radially compressed anchor106and a final or deployed configuration in which sensor102is at least partially located within a lumen of radially expanded anchor106shown inFIG. 5. As will be explained in more detail herein, in operation, struts104A,104B lock into an over-center position curved radially inward from their attachment points on anchor106to hold at least a distal portion of sensor102centered and located within the lumen120of expanded anchor106.

In order to percutaneously deliver and track implant100through a patient's vasculature, anchor106is radially compressed and struts104A,104B are generally straight to longitudinally separate or space sensor102apart from anchor106as shown in the implant delivery configuration ofFIG. 1. Longitudinally separating sensor102from anchor106, rather than locating sensor102within the lumen120of anchor106during delivery minimizes the profile of the delivery system.FIGS. 1-5illustrate implant100being transformed from the initial or delivery configuration in which sensor102is longitudinally separated from compressed anchor106to the final or deployed configuration in which at least a distal portion of sensor102is centered and locked within the lumen120of expanded anchor106.

Referring toFIGS. 1 and 2, radial expansion of anchor106is the first step of deploying implant100. Anchor106is a generally tubular or cylindrical stent-like structure having a lumen120therethrough and being transformable between the radially compressed configuration ofFIG. 1for transluminal catheter delivery within a vasculature and the radially expanded configuration ofFIG. 2for lodging against a vessel wall. In one embodiment, a plurality of radially compressible rings112is joined in series to form the cylindrical tubular body of anchor106. One of ordinary skill in the art will appreciate that anchor106can have any number of rings112depending upon the desired length of anchor106. For example when the target implantation site is relatively short, it would be desirable for anchor106to have a small number of rings such as between two and four rings. Rings112may have any suitable configuration, such as a zig-zag or sinusoidal wireform pattern of straight segments115with crowns114(i.e., alternating crowns facing opposite longitudinal directions) connecting adjacent straight segments115. After being radially crimped or otherwise compressed for delivery to a target site within a vessel, anchor106may radially self-expand or may be radially expanded via inflation of a balloon (not shown) such that anchor106securely engages the vessel wall. Those of ordinary skill in the art would recognize that anchor106may adapted from other known stent-like configurations. For example, and not by way of limitation, the anchor may be selected from self-expanding and balloon-expandable stents such as those shown and described in U.S. Pat. No. 4,733,665 to Palmaz, U.S. Pat. No. 4,800,882 to Gianturco, U.S. Pat. No. 4,886,062 to Wiktor, U.S. Pat. No. 5,133,732 to Wiktor, U.S. Pat. No. 5,292,331 to Boneau, U.S. Pat. No. 5,421,955 to Lau, U.S. Pat. No. 5,776,161 to Globerman, U.S. Pat. No. 5,935,162 to Dang, U.S. Pat. No. 6,090,127 to Globerman, U.S. Pat. No. 6,113,627 to Jang, U.S. Pat. No. 6,663,661 to Boneau, and U.S. Pat. No. 6,730,116 to Wolinsky et al., each of which is incorporated by reference herein in its entirety.

After radial expansion of anchor106into engagement with the vessel wall, sensor102is forced at least part way into lumen120of expanded anchor106such that the struts104A,104B are inverted into an over-center or locked position that holds at least a distal portion of sensor102radially centered within a proximal end of lumen120. More particularly, a force is applied to sensor102in the direction of arrow116to translate sensor102towards the expanded anchor106as shown inFIG. 3. The frictional engagement between anchor106and the vessel wall is expected to be sufficient to retain anchor106in the deployed position while resisting the force applied to translate sensor102. It should be understood that, without deviating from the teaching of the disclosure, the distal-to-proximal orientation of implant100described herein may be reversed such that sensor102is initially located distal to anchor106, in which case the force applied in the direction of arrow116is a pulling force rather than a pushing force. The force applied to sensor102causes struts104A,104B and one or more anchor rings112to which struts104A,104B are attached to controllably deform, bulging radially outward in the direction of arrows118A,118B, as shown inFIG. 3. Struts104A,104B thus expand and engage the vessel wall such that, in combination with outwardly deformed anchor ring112, the resistance of anchor106to dislocation by the transformation force is enhanced.

The configuration of implant100illustrated inFIG. 3may be considered to be a “neutral” configuration in that the bulging shape of struts104A,104B and ring112is inherently unstable. The deformation of struts104A,104B and ring112in an outward radial direction loads potential energy into the struts and ring112and, when released, the struts and ring112will tend to seek their least-energy position. That is, if the transformation force were removed at this point during transformation, then implant100could either revert itself back to the configuration shown inFIG. 2or implant100could automatically continue the transformation to the final deployed configuration shown inFIG. 5.

As the pushing force is continued to be applied in the direction of arrow116, struts104A,104B invert or curve inward in the direction of arrows120A,120B, respectively as shown inFIG. 4. In other words, first ends108A,108B of struts104A,104B longitudinally pass from a proximal side of second ends110A,110B to a distal side of second ends110A,110B (or vice versa if implant is initially located distal of anchor106). As struts104A,104B invert, the attached end of sensor102is longitudinally translated towards and into anchor lumen120. The potential energy in ring112is relieved, and struts104A,104B lock into an over-center position shown inFIG. 5to hold at least a portion of sensor102centered within lumen120of expanded anchor106. Struts104A,104B are considered to be locked in the over-center position because a substantial force would be required to deform struts104A,104B and ring112from their least-energy configuration as shown inFIG. 5to the neutral configuration as described above with respect toFIG. 3. Absent such a substantial force, struts104A,104B will remain locked in the over-center position ofFIG. 5. By disposing at least a portion of sensor102within lumen120of anchor106, the overall length of implant100is minimized, which may be particularly advantageous when implanting sensor102at an implantation site having a relatively short landing zone within the vessel.

Struts104A,104B, as well as anchor106, may be made from a variety of medical implantable materials, including, but not limited to, nickel-titanium (nitinol), stainless steel, tantalum, nickel, titanium, polymeric materials, nickel-cobalt-chromium-molybdenum “superalloy,” combinations of the above, and the like. In one embodiment, struts104A,104B are solid wire or wire-like members having an outer diameter that ranges between 0.006 and 0.050 inch and may have a length between 0.50 and 2.00 inches, although the dimensions may be scaled accordingly to match vessels of 4-60 mm in diameter. Struts104A,104B may be generally wire-like and have cross-sectional shapes known to those of ordinary skill in the art, including but not limited to circular, elliptical, or rectangular.

In one embodiment, struts104A,104B are pre-curved or heat-set in the curved or inverted configuration ofFIG. 5in which struts104A,104B curve radially inward from their attachment points on implant106towards and within the lumen120of anchor106. The heat-set configurations of struts104A,104B are imparted or set into the struts during the manufacturing thereof prior to implantation. Upon application of a sufficient pushing force, struts104A,104B transform from the generally straightened configurations ofFIG. 1into their heat-set configurations ofFIG. 5, thereby locking into the over-center position to hold at least a distal portion of sensor102centered within lumen120of expanded anchor106. By snapping back into predetermined or heat-set configurations, the struts104A,104B are even further locked into the final or deployed configuration because the force required to deform struts104A,104B would need to overcome both the over-center forces described above as well as the heat-set forces imparted to struts104A,104B during the manufacturing thereof.

Turning now toFIGS. 6-7, another embodiment of an implant600is shown.FIG. 6illustrates implant600in an initial or delivery configuration in which a sensor602is connected and longitudinally separated from a self-expanding anchor606by at least two struts604A,604B. In one embodiment, a plurality of radially compressible rings612is joined in series to form the cylindrical tubular body of anchor606. Rings612may have any suitable configuration, such as a zig-zag or sinusoidal wireform pattern of straight segments615with crowns614(i.e., alternating crowns facing opposite longitudinal directions) connecting adjacent straight segments615.FIG. 7illustrates implant600in a final or deployed configuration in which at least a distal portion of sensor602is centered within a lumen620of expanded anchor606. Struts604A,604B have first ends608A,608B, respectively, attached to a distal end of sensor602and second ends610A,610B, respectively, attached to a distal end of anchor606. It will be apparent to those of ordinary skill in the art that sensor602may alternatively be positioned distal to anchor606and first ends608A,608B, may be attached to the proximal end of sensor602and second ends610A,610B may be attached to a proximal end of anchor606. In addition, it will apparent to those of ordinary skill in the art that other positioning/attachment locations between struts604A,604B and anchor606are possible. For example, second ends610A,610B of struts604A,604B may be attached at other longitudinal positions along the length of anchor606such as approximately along a proximal portion of anchor606, a mid-point of anchor606, or a distal portion of anchor606.

Struts604A,604B are pre-curved or heat-set in a curved configuration as shown inFIG. 7in which struts604A,604B extend distally from their attachment points on the distal end of anchor606and then curve radially inward towards and within the lumen620of anchor606. The heat-set configurations of struts604A,604B are imparted or set into the struts during the manufacturing thereof prior to implantation. In one embodiment, the heat-set configurations of struts604A,604B are generally semi-circular. When implant600is loaded into a delivery system, sensor602is pulled such that struts604A,604B generally straighten out to longitudinally separate sensor602from anchor606as shown inFIG. 6, thus minimizing the profile of the delivery system. Rather than utilizing an externally applied pulling or pushing force to evert the struts over-center and longitudinally relocate the implant as in the embodiment ofFIGS. 1-5, implant600utilizes radial expansion of anchor606to pull or longitudinally relocate sensor602within the expanded anchor606during deployment. More particularly, when anchor606radially expands within a vessel, the diameter thereof increases from a first diameter D1of anchor606in the compressed or delivery configuration ofFIG. 6to a second diameter D2of anchor606in the deployed or expanded configuration ofFIG. 7. In an embodiment, second diameter D2is between 6 and 10 times the first diameter D1. For example, anchor606may have a compressed first diameter D1approximately equal to 3 mm, which is approximately equal to an outer diameter of sensor602, and an expanded second diameter D2between 20 mm and 40 mm. Struts604A,604B are pulled longitudinally inward and radially outward as anchor606radially expands, until struts604A,604B revert or snap back into their heat-set curved configurations. As a result, sensor602is longitudinally relocated to a position at least partially within lumen620of anchor606so that sensor602is radially centered inside the lumen of the vessel.

It will apparent to those of ordinary skill in the art that other preset curved configurations of struts604A,604B are possible depending on the relative dimensions, including expanded diameter and length, of anchor606. For example,FIG. 8illustrates a perspective view of a radially expanded anchor806having sensor802at least partially centered therein according to another embodiment hereof. In this embodiment, the expanded diameter of anchor806is approximately five (5) times the first compressed diameter. For example, anchor806may have a compressed first diameter approximately equal to 3 mm, which is approximately equal to an outer diameter of sensor802, and an expanded second diameter of approximately 15 mm. Shown in their preset and finally deployed configuration, struts804A,804B each include a distal portion824A,824B, respectively, that extends distally from their attachment points on the distal end of anchor806and then curve radially inward towards and within the lumen of anchor806and a generally straight proximal portion822A,824B, respectively, that connects to the distal end of sensor802. In this embodiment, the generally straight proximal portions824A,824B provide struts804A,804B sufficient length to ensure that sensor802is longitudinally separated from anchor806when implant800is loaded into a delivery catheter. As in the above embodiment ofFIGS. 6-7, radial expansion of anchor806causes struts804A,804B to be pulled longitudinally inward and radial outward during deployment until struts804A,804B revert back into their heat-set configurations, thereby longitudinally relocating sensor802to a position at least partially within a lumen of expanded anchor806.

FIG. 9illustrates a side view of a system950for delivering and deploying implant100having a self-expanding anchor106. Although described with respect to implant100, delivery system950may also be utilized for delivering implants600,800having self-expanding anchors606,806, respectively, or any other embodiment described herein that includes a self-expanding anchor. Self-expanding as used herein means that anchor106has a mechanical memory to return to an expanded or deployed configuration. Mechanical memory may be imparted to anchor106by thermal treatment to achieve a spring temper in stainless steel, for example, or to set a shape memory in a susceptible metal alloy, such as nickel-titanium (nitinol).

The delivery system950includes a retractable outer sheath930having a proximal end932and a distal end934, an intermediate or pusher tube936having a proximal end938and a distal end940, and an inner or core shaft942having a proximal end944and a distal end946. Proximal ends932,938, and944of sheath930, pusher936, and shaft942, respectively, each extend proximally outside of the patient's body such that they may be manipulated by the physician and may include a handle or knob in order to facilitate securing a longitudinal position or sliding movement thereof. Sheath930, pusher936, and shaft942are concentric in that pusher936slidingly extends through a lumen defined by sheath930and shaft942slidingly extends through a lumen defined by pusher936. Sheath930is an elongated tube that serves to constrain anchor106mounted on the inner shaft942into the radially compressed delivery configuration described above with respect toFIG. 1while delivery system950is tracked through a patient's vasculature to the deployment site. When sheath930is retracted, anchor106is released and radially expands as described above with respect toFIG. 2. Pusher936is an elongated tube that serves to apply the deployment force (i.e., a pushing or pulling force) to sensor102and also serves as a stopper that assists in deployment of self-expanding anchor106when outer sheath930is retracted. Shaft components930,936may be formed from a flexible polymeric material such as polyethylene terephthalate (PET), nylon, polyethylene, polyethylene block amide copolymer (PEBA), or combinations thereof. Shaft942is an elongated solid or tubular component that extends through pusher936to a distal tip948of delivery system950. Distal tip948is coupled to distal end946of shaft942, and may be tapered and flexible to provide trackability through the vasculature. In an embodiment where shaft942is a solid rod, shaft942is tracked to the target site with the assistance of tapered distal tip948. In an embodiment where shaft942is a tubular component, shaft942may define a guidewire lumen (not shown) for receiving a guidewire (not shown) therethrough. When the guidewire lumen is present, shaft942may be advanced over an indwelling guidewire to track the delivery system to the target site.

When loaded into delivery system950, sensor102is connected to but longitudinally separated from anchor106via struts104A,104B and is positioned between an inner surface of sheath930and an outer surface of shaft942. In the embodiment shown, pusher936need not be attached to sensor102because pusher936can simply provide a pushing deployment force against sensor102. However, if sensor102is initially located distal to anchor106such that a pulling deployment force is required, or if the ability to recapture sensor102and anchor106is desired, a proximal end103of sensor102may be releasably attached to a distal end940of pusher936. Pusher936serves to apply the pushing deployment force onto sensor102in order to longitudinally translate sensor102to a position within the lumen of anchor106, as described above with respect toFIGS. 3-5. Once sensor102is locked into position as desired, delivery system950may be proximally retracted and removed from the patient. If pusher936is releasably attached to sensor102, then pusher936is disconnected from sensor102prior to removal of delivery system950. Sensor102and pusher936may be releasably attached to each other in any suitable manner such as by mating screw threads.

A releasable connection between sensor102and pusher936may permit recapture and repositioning of the expanded anchor106. More particularly, initial deployment of anchor106may result in a less than optimal positioning or an inoperable positioning of implant100. A pulling force may be applied to sensor102to unlock and straighten struts104A,104B. Continued pulling of sensor102and/or advancement of sheath930radially compresses the proximal end of anchor106into sheath930. Once the proximal end of anchor106is collapsed into sheath930, sheath930may be re-advanced over anchor106to re-constrain the device therein. Implant100may then be repositioned and the deployment process may be repeated at the new implantation site.

In another embodiment, anchor106of implant100may be balloon-expandable. Anchor106may be crimped onto a conventional balloon dilation catheter for delivery to a treatment site where anchor106may be expanded by the radial force of the balloon. As the balloon expands, it physically forces anchor106to radially expand such that the outside surface of anchor106comes into contact with the vessel wall. The balloon is then deflated and collapsed leaving anchor106in the expanded or deployed configuration. Conventional balloon catheters that may be modified for use with implant100include any type of catheter known in the art, including over-the-wire catheters, rapid-exchange catheters, core wire catheters, and any other appropriate balloon catheters. For example, and not by way of limitation, conventional balloon catheters such as those shown or described in U.S. Pat. Nos. 6,736,827; 6,554,795; 6,500,147; and 5,458,639, which are incorporated by reference herein in their entirety, may be modified for use in conjunction with implant100of the present invention. Struts104A,104B are separately formed with a predetermined or heat-set configuration as described above, and subsequently connected to the balloon-expandable anchor106.

For example,FIG. 10is an illustration of a delivery system1001for tracking implant100having a balloon expandable anchor106to a target site in accordance with an embodiment of the present invention. Stent delivery system1001includes an over-the-wire catheter1003having a catheter shaft1005extending from hub1009to a distally-mounted balloon1007. Balloon1007is shown in an expanded or inflated configuration inFIG. 10. Inflation port1011of hub1009fluidly communicates with balloon1007via an inflation lumen (not shown) that extends through shaft1005. In addition, hub1009includes a guidewire port1013that communicates with a guidewire lumen (not shown) of shaft1005for receiving a guidewire1017therethrough. Anchor106is positioned over balloon1007and sensor102is releasably coupled to the outer surface of catheter distal tip1015, with struts104A,104B extending between anchor106and sensor102. Sensor102may be releasably coupled to catheter tip1015in any suitable manner. For example, catheter tip1015may have a helical connector (not shown) engaged with sensor102such that, after deployment of anchor106and deflation of balloon1007, catheter1003can be withdrawn to pull sensor102at least partially within anchor106. Then, catheter shaft1005can be rotated to disconnect tip1015from sensor102and catheter1003can then be withdrawn from the patient. If desired, a sheath may be provided to surround implant100to facilitate tracking of delivery system1001over guidewire1017through the vasculature to a site of a stenotic lesion.

Deployment of balloon expandable anchor106is accomplished by threading catheter1003through the vascular system of the patient until anchor106is located at a target location, for example, an implantation site for sensor102. Once positioned, balloon1007may be inflated to expand anchor106against the wall of the vessel as is known to one of ordinary skill in the art. With sensor102being located distal to anchor106as shown inFIG. 10, a pulling force in the direction of directional arrow1021is then applied to the proximal end of catheter tip1015to longitudinally relocate at least a portion of sensor102into a locked and centered position within the lumen of expanded anchor106.

In alternative balloon-expandable embodiment, sensor102may be located proximal to anchor106and releasably coupled to catheter shaft1005. After expanding anchor106, balloon1007must be deflated and a pushing force may be applied to shaft1005to longitudinally relocate at least a portion of sensor102into a locked and centered position within the lumen of expanded anchor106. Shaft1005is then disengaged from sensor102, and delivery system1001is proximally retracted and removed from the patient.