Duet stent deployment system and method of performing a transjugular intrahepatic portosystemic shunting procedure using same

A duet stent deployment system is used in a transjugular intrahepatic portosystemic shunt procedure. The device has a versatility of adjusting to a patient's anatomy in vivo. The system includes exactly two self expanding stents mounted on an inner catheter and covered by an outer sheath that is moved among a pre-deployment configuration, a first deployment configuration and a second deployment configuration to position the stents in an overlapping configuration from the portal vein, through a shunt and into the hepatic vein, and terminating at the junction with the vena cava.

TECHNICAL FIELD

The present disclosure relates generally to a duet stent deployment system that carries exactly two self expanding stents, and more particularly to a stent deployment system for transjugular intrahepatic portosystemic shunting procedures.

BACKGROUND

Transjugular intrahepatic portosystemic shunting (TIPS) is an artificial channel within the liver that establishes communication between the portal vein and the hepatic vein. TIPS is sometimes used to treat portal hypertension that is often due to liver cirrhosis, which frequently leads to intestinal bleeding, esophageal bleeding and the build up of fluids within the abdomen. The TIPS procedure works by gaining access to the liver via the jugular vein, and then moving through the vena cava to the hepatic vein. A needle is then used to create a point of access (shunt) from the hepatic vein through the liver tissue into the portal vein. A guide wire is introduced to maintain access, and then a balloon catheter is placed over the wire and into the liver tissue. The balloon is inflated in the shunt to create a conduit that will accommodate the forthcoming stent. The balloon is deflated and removed. A stent introducer is then inserted and the portal end of the stent is deployed. The rest of the stent is then released and the balloon is reinserted and reinflated to assure that the stent is fully patent. The stented shunt allows for pressure relief in the portal vein, and blood can return to mostly a normal path through the liver, and therefore reduce some of the symptoms described above.

There are a variety of problems associated with the current TIPS procedure. One problem is that the stent length and sometimes diameter needed for a patient is uncertain, even with careful measuring and estimation. Physicians would like to control the length and diameter of the stent during and post-procedure. For instance, due to substantial variations among patients' internal anatomy geometry, stent sizing can require that a hospital maintain a wide variety of stent introducers with stents of varying lengths to accommodate all potential patients. In addition, when it is necessary for the physician to complete the procedure with the implantation of two stents, the first stent introducer must be withdrawn and a second stent introducer must be brought into the patient, increasing costs, procedure times and complication risks to the patient. An additional problem is that this procedure is expensive due to physician operating time and materials. Lastly, a covered stent is often integral to the procedure, and physicians generally prefer longer sleeve covered stents. These covered stents have an outer coating that keeps bile out of the shunt, and may include an inner coating that promotes platelet growth and blood flow. European patent application EP 1044663A2 is of interest for teaching a sleeved intrahepatic endoprosthesis (stent) in which two members can be connected telescopically to adapt to the length of stenting required for a particular patient. However, this reference teaches mounting the two stent members on separate delivery devices requiring withdrawal of the first delivery device before the second stent can be implanted using a second delivery device.

The present disclosure is directly toward one or more of the problems set forth above.

SUMMARY OF THE DISCLOSURE

In one aspect, a duet stent deployment system includes exactly two stents mounted on a distal segment of an inner catheter. The two stents include a primary stent and a secondary stent. An outer sheath is slidably mounted on the inner catheter, and movable along an axis of the inner catheter from a pre-deployment configuration to a first deployment configuration, and then from the first deployment configuration to a second deployment configuration. The primary and secondary stents are covered by the outer sheath in the pre-deployment configuration. The primary stent is uncovered but the second stent remains covered by the outer sheath in the first deployment configuration. The primary and secondary stents are uncovered by the outer sheath at the second deployment configuration. The primary stent includes a sleeve covering, and the secondary stent is longer than primary stent, and both the primary stent and the secondary stent are self expanding stents.

In another aspect, a method of performing a TIPS procedure includes maneuvering the duet stent deployment system in the pre-deployment configuration to a position at which the primary stent is positioned within a shunt extending between a hepatic vein and a portal vein. The duet stent deployment system is re-configured from the pre-deployment configuration to the first deployment configuration to release the primary stent in the shunt. The duet stent deployment system is then re-positioned to a position at which the distal end of the secondary stent is positioned inside the primary stent, and a proximal end of the secondary stent is positioned at a junction at the hepatic vein to the vena cava. The duet stent deployment system is then reconfigured from the first deployment configuration to the second deployment configuration to release the secondary stent to extend from the junction to the position inside the primary stent.

DETAILED DESCRIPTION

Hospitals that perform TIPS procedures must normally inventory stent introducers with stents having a variety of lengths to accommodate both physician discretion in deciding a stenting length needed for a particular patient, as well as accommodating the substantial variety in different lengths among patients from a junction of the shunt with the portal vein to a junction of the hepatic vein with the vena cava. Because of the three dimensional structure of these passageways, It can often be time consuming to determine precise stenting length requirements for each individual patient. In many instances, the physician will implant a first sleeve covered stent in the newly made shunt with a first stent deployment device and then reenter with a second stent deployment device to place a second stent to extend from the shunt through the hepatic vein to the junction with the vena cava. While the first stent length is somewhat typical among patients, and being on the order of about four centimeters in length, the length of a second stent, if any is used, can vary substantially among different patients. The second stent being maybe on the order of 5-8 centimeters in length in order to accommodate most patients. The duet stent deployment system of the present disclosure allows for inventorying only a single device that inherently has the flexibility to accommodate the different stenting needs of particular patients, as well as provide the physician with the option of implanting a second stent in an overlapped configuration with the first stent to provide an overall stented length capability for virtually any patient anatomy. Furthermore, the duet stent deployment system can reduce procedure time over prior art TIPS procedures that require entering the patient multiple times with more than one stent deployment system. The duet stent deployment system of this disclosure can also help in reducing guess work in determining an appropriate length for a second implanted stent, if any.

Referring initially toFIGS. 1-4, a duet stent deployment system30includes exactly two stents60mounted on a distal segment35of an inner catheter31. The two stents60include a primary stent61and a secondary stent62. The primary stent61includes a sleeve covering64, which prevents fluid communication between the lumen defined by primary stent61and the surrounding tissue. The sleeve covering64may be made from PTFE, poly(ether)urethaneurea or an other biocompatible material. The secondary stent may include a sleeve covering that is identical to that of the primary stent, or may have a different sleeve covering, or no sleeve covering at all. In general, the sleeve covering the primary stent may be non-porous to prevent bile from leaking into the stent and therefore into the blood stream. An inner layer of the sleeve covering may be porous to allow platelets to attach. The secondary stent62will always be longer than the primary stent61, and both the primary stent61and the secondary stent62are self expanding stents of a type well known in the art. For instance, both primary stent61and secondary stent62as well as duet stent deployment system30may have features similar to currently available ZILVER® available from Cook Incorporated of Bloomington Ind. The length of the primary stent according to this disclosure excludes the length of any anchoring mechanism63, if any, of the first stent. While primary stent61may include an anchoring mechanism63, secondary stent62will not. Thus, the length of the first stent may be determined according to this disclosure by measuring a length of its sleeve.

An outer sheath40is slidably mounted on the inner catheter31, and is movable along an axis41of the inner catheter31from a pre-deployment configuration42to a first deployment configuration43, and then from the first deployment configuration43to a second deployment configuration44. As shown inFIGS. 1 and 2, the primary and secondary stents61,62are both covered by the outer sheath40in the pre-deployment configuration42. As shown inFIG. 3, the primary stent61is uncovered but the secondary stent62remains covered by the outer sheath40in the first deployment configuration43. As shown inFIG. 4, the primary and secondary stents61,62are both uncovered by the outer sheath40at the second deployment configuration44. Outer sheath40may be on the order of 80-125 centimeters in length, and may have an outer diameter on the order of 10 French, but other sizing would also fall within the scope of the present disclosure.

In one specific example, the primary stent61may be about four centimeters long, and the secondary stent is less than eight centimeters long, but still longer than the primary stent61. As used in this disclosure, the term “about” means that the number is rounded to a single significant digit. Thus, both 3.5 centimeters and 4.4 centimeters are about four centimeters according to the present disclosure. As is typical in known stent deployment systems, the duet stent deployment system30of the present disclosure may include a radiopaque marker51on the distal end of outer sheath40. In addition, inner catheter31may include a lumen sized to receive a wire guide that is used to gain access to the stenting location in a manner well known in the art. Duet stent deployment system30may also be similar to typical stent deployment systems by the inclusion of a port38, which is shown capped, to allow fluids to be injected through the space between the inner catheter31and outer sheath40in a known manner. Primary stent61and secondary stent62may have identical expanded outside diameters which are typical for TIPS procedures. For instance, the expanded outside diameters may be 8 or 10 millimeters, but other diameters could be utilized without departing from the intended scope of the present disclosure.

In the duet stent deployment system30shown inFIGS. 1-4, a hub32is attached to a proximal end33of the inner catheter. Outer sheath40is connected to a handle46that is slidably mounted on the inner catheter31. While this type of pin and pull actuation may be typical and well known in the art, other actuation structures that allow movement of outer sheath40with regard to inner catheter31would also fall within the inner intended scope of the present disclosure. For example, one handed devices that utilize a pull connected to the outer sheath that moves responsive to a thumbwheel would also fall within the intended scope of the present disclosure.

Duet stent deployment system30may include a first lock47that is movable between a locked position in contact with handle46as shown inFIG. 1and an unlocked position detached from handle46. Duet stent deployment30may also include a second lock48that is likewise movable between a locked position in contact with handle46as shown inFIG. 1and an unlocked position detached from handle46. First lock47and the second lock48may interact with a stop34(hidden from view), which may take the form of an enlarged diameter piece attached to inner catheter31. Lock47may inhibit movement of outer sheath40with regard to inner catheter31such as when duet deployment system30is in its pre-deployment configuration42. Those skilled in the art will appreciate that duet stent deployment system30will likely be in its pre-deployment configuration42during shipping, storage and while being maneuvered to a treatment site within a patient. In practice, the duet deployment system30is locked against movement from the pre-deployment configuration42to the first deployment configuration43when the first lock47is in the locked position as shown inFIG. 1. Likewise, the duet stent deployment system30is locked against movement from the first deployment configuration43to the second deployment configuration44when the second lock48is in the locked position as shown inFIG. 3. While locks47and48may be preferred, they are by no means necessary to the duet deployment system30. However, by utilizing locks47and48, there may be a lesser likelihood of errors from accidental partial deployment of either primary stent61or secondary stent62at other than a desirable placement location in the patient. As shown inFIG. 1, both first lock47and the second lock48are in contact with handle46when in their respective locked positions.

Apart from being loaded with exactly two stents60, duet stent deployment system30may also differ from stent deployment systems of the prior art by the inclusion of a ruler measurement segment49on one of the outer sheath40and inner catheter41. In the illustrated embodiment, a ruler measurement segment49is defined by radiopaque markers50that are equally spaced along axis41. Ruler measurement segment49and radiopaque markers50may appear similar to features associated with AUROUS® centimeter sizing catheters with a BEACON® tip currently available from Cook Incorporated of Bloomington Indiana. For instance, gold bands spaced one centimeter apart along the ruler segment49on the outer surface of outer sheath40may be utilized to assist a physician in measuring various key distances within the patient's anatomy. These key distances include distances between different landmarks within the patient. These landmarks include the location where the shunt opens to the portal vein, the junction of the shunt with the hepatic vein, and the distance from that junction to the vena cava. Although longer lengths would still fall within the scope of the present disclosure, the ruler measurement segment49may be less than twelve centimeters in length, since the combined length of a primary and secondary stent in even an extremely long deployment applications will still likely be less than ten centimeters. The ruler measurement segment49may be especially useful in measuring a distance from the patient's vena cava to a location inside the already deployed primary stent61in order to provide at least one centimeter overlap between the two stents61,62, while ensuring that the other end of the secondary stent62extends all the way to the vena cava in a three dimensional passage that may otherwise be difficult to measure with two dimensional imaging. Although not necessary, the distal end portion of primary stent62may include an anchoring mechanism63that is outside of sleeve covering64and assumes a flared shape when outer sheath40is withdrawn sufficiently to reveal anchoring mechanism63. Nevertheless, primary stent61need not necessarily include the optional anchoring mechanism63.

INDUSTRIAL APPLICABILITY

The present disclosure is generally applicable to any surgical procedure where at least one but no more than two self expanding stents are needed to perform a particular procedure. The disclosure is specifically applicable to procedures in which two stents need to overlap and have a combined length that is constrained by possible uncertain patient anatomy. The present disclosure finds specific applicability to transjugular intrahepatic portosystemic shunting procedures.

Referring now in addition toFIGS. 5-8a portion of a TIPS procedure that utilizes the duet stent deployment system30of the present disclosure is illustrated. Prior toFIG. 5, the TIPS procedure is typical with the creation of the shunt14through liver tissue10with an appropriate needle device (not shown). Thereafter, a wire guide22extends down through the patients vena cava13through a segment of hepatic vein12, through shunt14and into portal vein11. With the wire guide22properly positioned, the duet stent deployment system30is advanced over the wire guide22into the portal vein11. In other words, the duet stent deployment system30is maneuvered in its pre-deployment configuration42to a position at which the primary stent61is positioned within shunt14. Using appropriate imaging, the physician can confirm using radial opaque marker51, for instance, that the distal end of the duet stent deployment system30is properly positioned in the portal vein. This initial maneuvering of duet stent deployment system30may be performed with the device30in the pre-deployment configuration42as shown inFIG. 1. Utilizing the ruler measurement segment49, while duet stent deployment system30remains in the pre-deployment configuration42, the physician may utilize the radiopaque markers50to size the length17of shunt14, which extends from the entrance to shunt16at portal vein11, to the junction18where the shunt14connects to hepatic vein12. This information can be useful in confirming that the primary stent61is at least as long as the length17of shunt14. Next, the outer sheath40may be pulled back a slight distance so that anchoring mechanism63is released. Then, the entire duet stent deployment system30may be pulled backward until some resistance is felt when anchoring mechanism63bears against or contacts the wall of portal vein11, as best shown inFIG. 6. Deployment of anchoring mechanism63may or may not require movement of first lock47from its locked position to its unlocked position. However, if first lock47has not yet been moved to an unlocked position, after anchoring mechanism63is positioned to bear against the wall portal vein11, the first lock47may now be moved from its locked position to its unlocked position. In the event that the primary stent does not include an anchoring mechanism63, the physician may need to know precisely where the distal end of the primary stent61is when concealed by outer sheath40in the pre-deployment configuration42in order to ensure proper positioning of primary stent61when deployed.

The duet stent deployment system30is then reconfigured from the pre-deployment configuration42as shown inFIG. 1to the first deployment configuration of43as shown inFIG. 3to release the primary stent61in shunt14. When this occurs, the outer sheath40is slid with respect to inner catheter31to the first deployment configuration43to release primary stent61to occupy shunt14. After releasing the primary stent61, its positioning may be confirmed through appropriate imaging. Thereafter, the duet stent deployment system30is repositioned to prepare for deployment of the secondary stent62. At this point, the physician may use the ruler measurement segment49on outer sheath40to take a second measurement in order to assess where to place the secondary stent62. For instance, the physician may desire one end of secondary stent61to the to be located at the junction15of hepatic vein12to vena cava13, and the opposite end of the secondary stent61to be positioned inside, in an overlapping relationship with primary stent61. Uncertainty arises in accurately determining the distance19from the patient's vena cava to the junction of shunt14with the hepatic vein12. The secondary stent should be long enough to accommodate measurement distance19plus an overlap distance20. To be clear, the primary stent61overlaps secondary stent62. This overlap may occupy this distance as shown as measurement20inFIG. 8. It may be desirable that a minimum overlap of one centimeter be achieved. However, a greater overlap, a lesser overlap or no overlap at all would also fall within the intended scope of the present disclosure. In order to inhibit bile from entering the bloodstream, no portion of the tissue wall that defines shunt14should be left uncovered.

After the measurement distance19is noted using the radiopaque markers of ruler measurement segment49, the duet stent deployment system30can be properly positioned with the help of radiopaque marker51, and knowing where secondary stent62is positioned on inner catheter31with respect to radiopaque marker51. Thus, the duet stent deployment system30may be repositioned to a position at which the distal end of the secondary stent62is positioned inside the primary stent61, and a proximal end of this secondary stent62is positioned at junction15of the hepatic vein to the vena cava13. The secondary stent62can now be readied for release. If included, the second lock48can be moved from its locked position to its unlocked position, by removing the pin from the system30, and the outer sheath40slid with respect to inner catheter31to release and implant the secondary stent62. In other words, the duet stent deployment system30is reconfigured from the first deployment configuration43as shown inFIG. 3to the second deployment configuration44as shown inFIG. 4to release the secondary stent62to extend from the junction to the vena cava to a position inside primary stent61. Thereafter, the duet stent deployment system30can be withdrawn from the patient leaving wire guide22in place. If deemed necessary, a balloon catheter (not shown) can be maneuvered along wire guide22and inflated within both the primary stent61and the secondary stent62, especially at the main junctions16,18and15to ensure patency of the stents. When completed, the combined primary stent and secondary stent70may have an overlapping configuration and extend from the entrance16to shunt14all the way to junction15where hepatic vein12connects to vena cava13.

Those skilled in the art will appreciate that if first and second locks47and48are included, the first lock is maintained in its locked position and the second lock48is maintained in its locked position while the duet stent deployment system30is being maneuvered in the predeployment configuration42. Likewise, the second lock48may be maintained in its locked position during the step of reconfiguring the duet stent deployment system30from the predeployment configuration42to the first deployment configuration43. In addition, the second lock48may be maintained in its locked position while the duet stent deployment system30is being repositioned prior to deployment of the secondary stent62. Finally, the second lock48may be moved to its unlocked position to enable movement of the duet stent deployment system30from the first deployment configuration43to the second deployment configuration44. Unlike prior art TIPS procedures, both the primary stent61and the secondary stent62are both deployed prior to withdrawal of the inner catheter31from the patient.

By utilizing exactly two stents60on a single delivery system30, the physician is allowed great flexibility on the fly during the TIPS procedure. In addition, loading of the two stents60on the single introducer30allows for fewer interventions and a single access into the patient, thus saving time and reducing patient risks during the TIPS procedure. If utilized, the dual safety lock strategy (first and second locks47and48) may be provided in order to prevent accidental deployment of the secondary stent62before adjustment has been made after the primary stent61has been deployed. This single access technique may reduce costs verses delivering two separate stents with two separate delivery catheters. The TIPS procedure time is also reduced with requirement of only a single access. Furthermore, hospitals may need to only inventory a small number of duet stent deployment systems30to accommodate the wide variety of potential patients, verses inventorying multiple stent deployment systems each loaded with stents of different lengths in order to accommodate the needs of particular patients. One important aspect of the TIPS procedure to note is that some physicians place a second stent if the first stent is not long enough to extend from the portal vein11to the vena cava13. This can be a burden because the physician may have to use an expensive stent with anchoring features, which should be unnecessary, and may be problematic for the secondary stent62. Thus, duet stent stent deployment system30may include exactly one stent with an anchoring mechanism63. If included, the anchoring mechanism63may have a structure similar to the anchor feature appearing in stents available from Cook Incorporated of Bloomington Ind.