Patent Application
20080294188
The present invention relates to the field of medical devices. Particularly, the present invention pertains to a holder for an expandable implant and a method of using the holder for the purpose of delivering an expandable implant into a blood vessel in a patient's body.
Expandable medical implant devices are well known in the art. Such devices may include filters, stents, endografts, prosthetic valves such as venous valves, occluders, embolic coils, or any other type of expandable medical device with an asymmetrical configuration that can be delivered to a treatment point within a body vessel. Specifically, devices such as filters can be used in the vena cava, among other places. Such filters are often referred to as vena cava filters. Vena cava filters can have many different shapes or sizes, but typically, they have one or more sets of filtering legs that form a cone at one end of the filter that is open toward the direction of the blood flow. The filtering legs help to prevent large blood clots from passing through the filter, while permitting blood to flow through the filter. This helps prevent blood clots from reaching a patient's pulmonary arterial system, thereby alleviating potentially fatal consequences that could occur as a result of a pulmonary embolism (PE). The filtering legs can also have barbs or hooks on the ends of the filtering legs to help anchor the filter inside of the blood vessel. The filter may also have a hook for retrieval of the filter. For patients with deep vein thrombosis (DVT), or blood clotting within the deep venous system, the filter may be left in the vessel long-term, or the filter may be temporarily left in a patient, and thereafter retrieved.
Vena cava filters are most commonly placed in the inferior vena cava vein to capture clots originating from the lower extremities. The filter may be placed either below the renal veins (i.e., infra-renal placement) or above the renal veins (supra-renal placement). Vena cava filters may be placed in the superior vena cava vein. Although not as common, there is a growing trend toward placing filters in the superior vena cava due to the increase in use of long term vascular access devices such as central venous catheters and pacemakers. A common complication of these long term devices is upper-extremity DVT which may result in a potentially fatal PE. SVC filter placement can prevent PE associated with these long-term vascular access devices by capturing clots originating from the upper extremities.
Vena cava filters must be inserted into the blood vessel in the proper direction, i.e., the open end of the filter cone must be positioned upstream of the cone apex or hub so as to capture and retain clots within the cone. As blood flows through the open end of the cone, blood clots are caught inside of the filter cone and are pushed downstream into the center of the filter, where they are dissolved through the lysing action of the blood flow. Even non-conical filters may require a specific axial orientation within the vessel, due to anchoring barb orientation and/or retrieval hook position.
Filters placed in the inferior vena cava are typically inserted percutaneously via the femoral vein using the Seldinger technique. Access can also be achieved through the right internal jugular vein. This is advantageous in cases where there is thrombus in the iliac vein. Although the femoral and jugular approaches are most common, as medical devices and delivery systems become smaller, smaller vessels can be used as insertion sites, providing the physician with a broader range of access sites to choose from. Such alternative access sites may include, but are not limited to, brachial, antecubital, basilic, or subclavian venous access sites.
Because expandable implant devices, such as filters, may be inserted into blood vessels from different approaches, depending on the access site, it is critical for a physician to be able to insert an implant into the blood vessel with the proper axial orientation, i.e., with the open end of the filter cone positioned upstream of the apex. If the implant is placed in the wrong orientation in the blood vessel, the implant could be ineffective in capturing blood clots, which could put the patient at risk for pulmonary embolism. The wrong orientation of a filter could also result in localized thrombus build-up caused by turbulent blood flow around the mis-positioned filter. Localized thrombus build-up could lead to partial or complete vessel occlusion. An “upside-down” filter is also susceptible to migration because the anchoring elements, usually barbs or hooks, are typically designed to engage the vessel at a predetermined angle. If this angle is reversed, as would be the case in an incorrectly oriented filter, the anchors may not be able to retain the filter in place under a clot load, resulting in migration. This could lead to potentially fatal outcomes.
If the filter is inserted with the wrong orientation, the physician has two options to correct the error: retrieve the filter or leave the filter in place and insert another filter in the correct orientation. The physician may choose to simply place a second filter in the general vicinity of the first incorrectly oriented filter using the same access route. If the physician chooses to retrieve the mis-oriented filter, a second procedure is required to place a retrieval device through another insertion site in the patient's body. As an example, if the filter was incorrectly deployed using a jugular approach in the inferior vena cava, the retrieval hook would be positioned in a downstream direction, requiring a femoral retrieval approach. Both options may present additional complications associated with multiple insertion attempts and lengthened procedure time.
Placing a filter in the SVC with the correct orientation is even more critical because the “landing zone” of the SVC, or the segment defined by the SVC-right atrial junction and the confluence of the left and right brachiocephalic veins, is shorter than the IVC. This provides a relatively small area for safe filter deployment. Thus, it is not feasible to leave a filter in the SVC with the wrong orientation and to place another filter in the SVC. Instead, the filter must be retrieved prior to a second placement attempt. The location of the parietal pericardium relative to the SVC is also very variable. If the filter legs push through the SVC and penetrate the pericardium, it may cause tamponade and heart failure. Thus, it is critical to ensure that the filtering leg anchoring mechanisms are located in the proper orientation so as to reduce the risk of penetration.
Expandable medical implant devices, such as filters, are typically deployed using catheter-based delivery systems. Such delivery systems may optionally include a cartridge or other holder containing the implant in a collapsed position. Cartridges are pre-loaded with the implant in a pre-determined orientation by the manufacturer. Such cartridges may also have arrows or words marked on the outside of the cartridge, which indicate the orientation of the expandable implant inside the cartridge. Cartridges typically have two ends, one of which is attached to a delivery catheter. A pusher wire is then inserted into the cartridge through lumen. The pusher is used to advance the collapsed implant device through the catheter lumen, and into the blood vessel.
Several cartridges have been proposed to assist physicians in determining the correct orientation of expandable implant devices, such as filters. Such cartridges have different arrows, labels and/or indicators located on the cartridge, indicating “femoral” or “jugular,” corresponding to the desired orientation. These indicia show which end of the cartridge to insert first into a catheter to assist in proper orientation of the filter during delivery and treatment. Such filter cartridges may also have different shaped ends which can be connected to the catheter, depending on whether the femoral or jugular access sites are chosen. For instance, one end may be a square shape and the other may be a triangle or circle shape.
The use of pre-loaded filter cartridges is advantageous because it reduces the inventory a hospital is required to carry. Since the physician determines the orientation of the cartridge relative to the catheter, a single delivery system is stocked for either the femoral or jugular approach. Although the use of attachable cartridges has reduced the inventory hospitals are required to carry, there is an increased risk that the physician might make an error when attaching the cartridge to the catheter, causing the filter to be deployed in the wrong orientation, as described above.
Medical filter cartridges also have other disadvantages. The markings on current filter cartridges may not provide indicia for insertion into alternate access sites, other than the femoral or the jugular approaches. In addition, these cartridges cannot be used to indicate correct orientation of the device when placed in the superior vena cava. The blood flow in the SVC is opposite that of the IVC. Thus, to maintain the correct orientation of the filter in the SVC, a filter designed for jugular access must be placed via a femoral approach, whereas a filter designed for femoral access must be placed via a jugular approach. Any filter orientation indicator that uses arrows or text labeling cannot be applied to the SVC without placing the filter in the opposite direction from the indicator direction.
Although the presence of arrows pointing in certain directions or different shaped ends of the filter allegedly aid the physician in figuring out which end of the cartridge to attach to the catheter, the physician may still not know whether the pre-loaded filter that is inside of the cartridge is in the proper orientation. Filter deployment errors are often due to operator error while using a filter delivery mechanism. The physician may mistake the orientation of the filter by misinterpreting the arrows, colors, or other indicia on the cartridges. The Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database contains numerous reports involving users deploying filters with the wrong orientation using cartridges with directional indicators. Specifically, it was reported recently that an operator misunderstood the meaning of the arrows and labels on a Cordis OptEase® vena cava filter cartridge and deployed the filter in the wrong direction.
All of the currently proposed cartridge designs present the risk that the physician will still attach the delivery catheter to the wrong end of the cartridge, which could result in the deployment of the filter inside of the blood vessel in the wrong orientation. Thus, there has been, and continues to be, a need for a solution to the above mentioned problems, such as a device and method which allows a physician to reliably and accurately determine the orientation of an expandable implant device that is located inside of a cartridge, before attaching the pre-loaded implant cartridge to a delivery catheter and deploying the implant inside of a blood vessel.
An implant device holder for use with a delivery catheter to deploy an implant device in a tubular body part is provided. The holder includes a cartridge body having a lumen extending between two ends, holding a collapsed implant device, and displaying an implant image. The implant image has an axial orientation corresponding to the axial orientation of the implant held in the cartridge body lumen. The axial orientation of the implant image helps to guide a physician in correctly orienting the implant regardless of which access point is used, thereby reducing the chance of deploying the implant in the wrong axial direction.
According to another aspect of the disclosure, a method of deploying an implant device in a tubular body part using an implant holder is provided. The holder has a cartridge body having a lumen extending between two ends and an implant image that has an axial orientation corresponding to the axial orientation of the implant held in the cartridge body lumen. A delivery catheter is inserted into a tubular body part through an access site. Based on the axial orientation of the implant image disposed on the cartridge body and the location of the access site, the implant cartridge body is oriented such that either one or the other end of the cartridge body faces a proximal end of the delivery catheter. The oriented cartridge body is then attached to the proximal end of the delivery catheter. The implant device contained in the attached cartridge body is moved in a distal direction so as to deploy the implant.
According to the invention, an image 16 of the expandable implant 4 is disposed on the cartridge body 8. Preferably, the image 16 represents the implant device 4 in a fully expanded state and has an axial orientation corresponding to the axial orientation of the implant device 4 held in the cartridge body lumen 10. However, the image 16 could be in a partially expanded or even collapsed state so long as the axial orientation of the implant image 16 can be ascertainable by a physician and that it corresponds to the axial orientation of the implant device 4. In one implementation, a thin self-adhesive film containing the implant image 16 is attached to an outer surface of the cartridge body 8. The implant image 16 may also be in the form of a printed image, an embossed label, a raised imprint on the cartridge body 8 that is produced by injection molding and is part of the cartridge body 8, or any other suitable permanent form. Alternatively, the implant image 16 may be the filter cartridge body 8 itself. The implant image 16 may be made of any suitable color or design, including clear or transparent. The implant image 16 may be disposed anywhere on the cartridge body 8, including any inner or outer surface of the cartridge body 8.
The expanded implant image 16 takes up a larger surface area than the collapsed implant 4. The cartridge body 8 has a pair of radially extended wings 29, 31 over which the implant image 16 extends. Advantageously, the implant image 16 feature allows a physician to visually check how and in which direction the collapsed implant device 4 in the lumen 10 will be deployed into the expanded state inside the blood vessel 6, as will be discussed more fully later herein. In another embodiment, the cartridge body may optionally have indicators in addition to or in place of the implant image 16, such as, but not limited to, arrows, or other markers, indicating the direction of blood flow relative to the implant device 4 (as shown in
The cartridge body 8 includes first and second luer connectors 26, 28 that securely connect the implant device holder 2 to the delivery catheter 32. The cartridge body 8 also includes first and second hollow extensions 22, 24, respectively at the first and second ends 12, 14. Each extension 22, 24 is adapted to open a hemostasis valve of the delivery catheter 32. The valve is used to prevent leakage of fluids through the proximal end of the delivery catheter 32. The extensions 22, 24 also serve to prevent a standard luer connectable device from being erroneously connected to the luer connectors 26, 28, thereby acting as a safety feature. The extensions 22, 24 thus help to prevent the cartridge body 8 from being connected to the wrong catheter.
Between the extensions 22, 24 is a single through lumen 10 that extends through the center of the cartridge body 8 and is in communication with the catheter 32. The length and diameter of the through lumen 10 can be of any suitable dimensions, depending on the type of expandable implant device 4 used. Although the cartridge body 8 is illustrated herein as having a square or semi-rectangular shape, the cartridge body 8 may have any suitable shape. Such shapes may include, but are not limited to, a round cylindrical shape like a tube design, as illustrated in
The expandable implant device 4 contained in the holder 2 is deployed using a delivery system 30 as shown in
Thus, in a key advantage of this invention, the risk of deploying a filter or other expandable implantable device 4 in the wrong orientation is minimized. The physician is not required to interpret indicators such as arrows or words alone, but instead is presented with an implant image 16 clearly depicting the final orientation of the expanded device 4 when deployed, making the decision of which end of the holder 2 to attach to the catheter 32 clear to the physician. In addition, the physician is not restricted to femoral or jugular approaches, but may utilize this invention to deploy an asymmetrical implant 4 from any desired access approach, as the physician can reliably and accurately determine the correct orientation of the implant 4 for deployment in the vessel 6 with differing blood flow patterns, such as in the upper versus lower extremity vasculature.
Another advantage of the present invention is that it provides one easy to use, low-cost, single kit for physicians and hospitals, which may be used with any access site in a patient's body. This eliminates the need for physicians and hospitals to carry an inventory of different pre-loaded delivery systems that are specific to either the femoral or the jugular approaches. The implant image 16 on the cartridge body 8 is also advantageous in that it serves as a quality control mechanism to ensure that manufacturing personnel will pre-load the filter 4 into the cartridge body 8 in the proper orientation. The implant image 16 provides a convenient visual identifier for manufacturing personnel, thereby allowing the expandable implant device 4 to be more accurately and reliably loaded into the holder 2 in the correct orientation.
A procedure for deploying the expandable implant device 4 into a blood vessel 6 will now be described in detail. Although the femoral vein access approach will be described herein, any desired access point may be used, such as, but not limited to, jugular, brachial, antecubital, basilic, or subclavian venous access sites. The expandable implant device 4 may be deployed inside any tubular body part, including ducts. The blood vessel 6 may be, but is not limited to, the inferior or superior vena cavae.
Once the delivery catheter 32 is in place, the physician uses the implant image 16 on the cartridge holder body 8 to determine the correct axial orientation of the collapsed filter 4. For a femoral approach, the physician orients the cartridge holder 2 with the luer connector 28 facing the proximal end of the delivery catheter 32. This orientation positions the conical apex of the filter 4 in the downstream direction, as illustrated by the arrows, once deployed. Once properly oriented, the expandable implant device holder 2 is securely attached to the proximal end of the delivery catheter 32, as shown in
The pusher 34 is next inserted into the cartridge body 8 through the first extension 22, as shown in
Referring now to
To deploy the filter 4 within the vessel 6, the pusher wire 34 is inserted through lumen 10 of holder 2, as shown in
As discussed above, the axial orientation of the implant image 16 corresponds to the axial orientation of the implant device 4 held in the cartridge lumen 10 to clearly show which direction the implant device 4 would deploy. This feature helps to guide the physician in correctly orienting the filter 4 regardless of which access point is used, thereby reducing the chance of deploying the filter 4 in the wrong axial direction. Although the method described herein covers deployment of a filter 4 in the blood vessel 6 using femoral and jugular approaches, other tubular body parts and approaches are within the scope of this invention.
The method disclosed herein may be used to deploy single expandable implants 4 or multiple expandable implant devices 4, of the same or different types, depending on the type of treatment and access site chosen. In the case of multiple implants 4, multiple implant images 16 may be used on the cartridge body 8 to aid a physician with the correct orientation of the filter 4, provided that the implant images 16 convey the correct axial orientation of the corresponding implants 4.
The present invention also encompasses a kit to be used with the method of the present invention. The kit may include, but is not limited to, the delivery catheter 32, implant holder/cartridge 2, at least one expandable implant device 4 that may be pre-loaded in the implant holder 2, and pusher 34.
The foregoing specific embodiments represent just some of the ways of practicing the present invention. Many other embodiments are possible within the spirit of the invention. Accordingly, the scope of the invention is not limited to the foregoing specification, but instead is given by the appended claims along with their full range of equivalents.
