Patent Publication Number: US-2023137558-A1

Title: Compound valve system for intracardiac tools

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to prior filed U.S. Provisional Patent Application No. 63/272,722 filed on Oct. 28, 2021, which is hereby incorporated by reference as set forth in full herein. 
    
    
     FIELD 
     The present invention relates to valves for catheter delivery, and in particular hemostasis valves for a sheath introducer. 
     BACKGROUND 
     A “sheath” or “sheath introducer” includes a tube placed in an artery or vein of a patient during a medical procedure that, when positioned for treatment, has a distal end within the artery or vein and a proximal end outside of the patient. A hemostasis valve at the proximal end of the sheath inhibits blood from exiting the sheath and allows longer sheaths and/or catheters to be inserted through the sheath into the artery or vein. 
     A problem with some current sheath introducers for catheter delivery is that movement of devices through the sheath can result in a pressure differential between an inner lumen of the sheath and the ambient environment which can potentially allow for air entrainment and/or leakage through the seal of the sheath. 
     SUMMARY 
     The present invention relates to valves for catheter delivery, and in particular hemostasis valves for a sheath introducer. 
     An example catheter sheath assembly can include an elongated shaft, a primary hemostatic valve assembly, and a secondary hemostatic valve assembly. The elongated shaft can include a distal end, a proximal end, and a lumen extending along a longitudinal axis and providing a passageway into the proximal end of the shaft and out of the distal end of the shaft. The primary hemostatic valve assembly can fluidically seal to the proximal end of the elongated shaft and include a primary seal. The secondary hemostatic valve assembly can include a secondary seal disposed in a proximal direction in relation to the primary seal such that the primary hemostatic valve assembly and the secondary hemostatic valve assembly define an intermediate chamber disposed at least in part between the primary seal and the secondary seal. 
     The secondary seal can be movable in relation to the primary seal to thereby change an internal volume of the intermediate chamber. The secondary seal can be configured to slide parallel to the longitudinal axis and within a housing portion of the secondary hemostatic valve assembly. The housing portion can be fixed in relation to the primary seal. The change in volume can be equal to an interior cross-sectional area of the intermediate chamber orthogonal to the longitudinal axis multiplied by a change in longitudinal position of the secondary seal. The secondary seal can be configured to move in response to a pressure differential between the intermediate chamber and an external environment. The internal volume of the intermediate chamber being configured to change in response to a difference in pressure between the intermediate chamber and an external environment. 
     The secondary hemostatic valve assembly can further include one or more springs configured to change in length to thereby move the secondary valve opening in relation to the primary valve opening. The change in volume can be based at least in part on stiffness of the one or more springs. The one or more springs can be configured to compress to increase the volume of the intermediate chamber. 
     The primary seal can include a primary valve opening aligned to the longitudinal axis. The secondary seal can include a secondary valve opening aligned to the longitudinal axis. 
     The intermediate chamber can be fluidically sealed from an external environment by the secondary seal and can be sealed from the lumen of the elongated shaft by the primary seal. 
     The intermediate chamber can be shaped by a tubular housing portion extending between the secondary seal and the primary seal. 
     The catheter sheath assembly can further include a handle joining the elongated shaft to the primary hemostatic valve assembly. The handle can be configured to be manipulated to reshape the elongated shaft. The secondary hemostatic valve assembly can include latch extensions configured to slide over a proximal end of the handle and latch to the proximal end of the handle to thereby create the intermediate chamber. Alternatively, the secondary hemostatic valve assembly can be integral to the handle. 
     The primary valve opening can be expandable to a larger diameter than the secondary valve opening. 
     The catheter sheath assembly can further include an aspiration port in fluidic communication with the fluidically sealed chamber. 
     The catheter sheath assembly can further include an interior housing including a funnel opening have a wide proximal end positioned in a distal direction from the secondary seal and a narrow distal end positioned in a proximal direction from the primary seal. 
     The interior housing can be configured to urge an intralumenal device being inserted into the proximal end of the catheter sheath assembly toward the longitudinal axis and the primary valve opening. 
     An example assembly can include a secondary valve accessory device and a catheter. The secondary valve accessory device can include a secondary seal, a tubular inner housing extending distally from the secondary seal, and an outer housing structurally supporting the secondary seal and the tubular inner housing. The catheter can include an elongated shaft and an end effector. The elongated shaft can define a longitudinal axis and extend through the secondary seal. The end effector can be positioned within the tubular inner housing. 
     The outer housing can further include a mating feature configured to engage a proximal end of a sheath introducer. The mating feature can include a latch extension. Additionally, or alternatively, the mating feature can include threads. 
     The tubular inner housing can include a distal end configured to seal to a proximal end of a primary hemostasis valve of a sheath introducer so that an intermediate chamber is bounded by the tubular inner housing, the secondary seal, and a primary seal of the primary hemostasis valve. 
     The secondary valve accessory device can include an O-ring disposed around an outer surface of the tubular inner housing. 
     The tubular inner housing can include a tapered portion having a wider diameter approximate the secondary seal and tapering to a narrow diameter distally from the secondary seal. 
     The secondary seal can include a secondary valve opening sized to allow the elongated shaft of the catheter to slide longitudinally therethrough and sized to inhibit the end effector of the catheter to slide longitudinally therethrough. 
     The secondary seal can be configured to translate proximally in relation to the tubular inner housing and outer housing in response to a force applied in a proximal direction to the secondary seal. 
     The secondary valve accessory device can further include a spring providing a spring force between the secondary seal and the outer housing. 
     The assembly can further include a sheath introducer including a primary hemostatic valve assembly. The primary hemostatic valve assembly can include a primary seal. The sheath introducer can be attached to the secondary valve accessory device such that the secondary seal is positioned in a distal direction in relation to the primary seal and an intermediate chamber is bounded at least in part by the secondary seal, the primary seal, and the tubular inner housing. 
     An example method of treatment can include one or more of the following steps presented in no particular order. The example method can include additional steps as would be appreciated and understood by a person having pertinent skill in the art. The example method can be performed using an example assembly as disclosed herein, a variation thereof, or an alternative thereto as would be appreciated and understood by a person skilled in the pertinent art. 
     An assembly comprising a secondary valve accessory device and a catheter can be selected such that an elongated shaft of the catheter extends through a secondary seal of the secondary valve accessory and an end effector of the catheter is positioned within a tubular inner housing of the secondary valve accessory. 
     An outer housing of the secondary valve assembly can be attached to a proximal end of a sheath introducer such that the secondary valve is aligned with a primary valve of the sheath introducer and an intermediate chamber is bounded at least in part by the secondary seal, the primary seal, and the tubular inner housing 
     The catheter shaft can be moved distally to thereby move the end effector of the catheter out of the tubular inner housing and through the primary seal. 
     These and other aspects of the disclosed technology are described herein along with the accompanying figures. Other aspects, features, and elements of the disclosed technology will become apparent to those skilled in the pertinent art upon reviewing the following description of specific examples of the disclosed technology. While features of the disclosed technology may be discussed relative to certain examples and figures, the disclosed technology can include one or more of the features or elements discussed herein. Further, while one or more examples may be discussed as having certain advantageous features, one or more of such features may also be used with the various other examples of the disclosure discussed herein. In similar fashion, while certain examples, implementations, and embodiments may be discussed below with respect to a given device, system, or method, it is to be understood that such examples can be implemented in various other devices, systems, and methods of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example sheath introducer assembly with a secondary valve accessory device detached from a sheath introducer according to aspects of the present invention. 
         FIG.  2    illustrates an example catheter and secondary valve assembly including an intralumenal device and the secondary valve accessory device according to aspects of the present invention. 
         FIG.  3 A  illustrates a side view of a proximal end of the example sheath introducer assembly with the secondary accessory device attached to the sheath introducer according to aspects of the present invention. 
         FIGS.  3 B and  3 C  illustrate cross-sectional views of the example sheath introducer assembly as indicated in  FIG.  3 A  according to aspects of the present invention. 
         FIG.  4    illustrates an exploded view of an example secondary valve accessory device according to aspects of the present invention. 
         FIG.  5    illustrates a cross-sectional view of a secondary hemostatic valve assembly of the secondary valve accessory device in which a seal of the secondary hemostatic valve assembly is in a first position according to aspects of the present invention. 
         FIG.  6    illustrates a cross-sectional view of the secondary hemostatic valve assembly in which the seal of the secondary hemostatic valve assembly is in a second position according to aspects of the present invention. 
         FIG.  7    illustrates a sheath introducer assembly in use according to aspects of the present invention. 
         FIG.  8 A  illustrates another example secondary valve accessory device according to aspects of the present invention. 
         FIG.  8 B  illustrates a cross-sectional view of the secondary valve accessory device as indicated in  FIG.  8 A  according to aspects of the present invention. 
         FIG.  9    illustrates a cut-away view of another example sheath introducer assembly including the secondary valve accessory device illustrated in  FIGS.  8 A and  8 B  according to aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±20% of the recited value, e.g., “about 90%” may refer to the range of values from 71% to 99%. 
     As used herein, the terms “comprising” or “containing” or “including” are interpreted to mean that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, method steps, even if the other such compounds, material, particles, method steps have the same function as what is named. 
     As used herein, the use of the term “external environment” is interpreted to mean an environment external to a medical device or assembly. When referring to the external environment of a medical device, assembly, or portion thereof that is external to a patient, the “external environment” is interpreted to be external to the patient. For instance, the “external environment” can include an environment in which a user interacts with the medical device/assembly. 
     As used herein, the use of terms such as “having,” “has,” “including,” or “includes” are open-ended and are intended to have the same meaning as terms such as “comprising” or “comprises” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” are intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such. 
     As used herein, the terms “tubular” and “tube” are to be construed broadly and are not limited to a structure that is a right cylinder or strictly circumferential in cross-section or of a uniform cross-section throughout its length. For example, the tubular structure or system is generally illustrated as a substantially right cylindrical structure. However, the tubular system may have a tapered or curved outer surface without departing from the scope of the present invention. 
     Ranges described as being between a first value and a second value are inclusive of the first and second values, as well as all values therebetween. Likewise, ranges described as being from a first value and to a second value are inclusive of the first and second values, as well as all values therebetween. 
     It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. 
     The components described hereinafter as making up various elements of the disclosure are intended to be illustrative and not restrictive. Many suitable components that would perform the same or similar functions as the components described herein are intended to be embraced within the scope of the disclosure. Such other components not described herein can include, but are not limited to, for example, similar components that are developed after development of the presently disclosed subject matter. 
     In some examples presented herein, a secondary valve can be connected to the proximal end of a sheath introducer to work in conjunction with a primary valve of the sheath introducer, thereby resulting in a compound valve system. In some examples, the compound valve system can reduce air entrainment into the sheath introducer compared to a similar sheath introducer lacking the secondary valve because the secondary valve inhibits air from traveling through the compound valve system. Additionally, the compound valve system can be modified to dampen pressure buildups during catheter retraction by allowing internal volume expansion with pressure increase within the sheath introducer with compound valve. 
     The compound valve system can be integral to the sheath introducer or integral to a secondary valve accessory device that can be attached to a proximal end of the sheath introducer. 
     In some examples, the secondary valve can be designed to interface with a specific diameter of intralumenal device (e.g., specific catheter shaft diameter). In some such examples, the secondary valve opening can be sized large enough to allow a catheter shaft to pass therethrough but too small to allow a larger end effector to pass therethrough. In some such examples, the secondary valve can be integral to a secondary valve accessory device that can be built onto an end effector introducer tool so that the secondary valve accessory device is integral to the intralumenal device. Such examples can allow easy insertion of a large end effector of a catheter through a primary valve having a larger opening than the secondary valve opening. The smaller secondary valve opening can be effective to reduce risk of leak and air entrainment. 
     In some examples, the compound valve system can include an aspiration port to reduce pressure between the primary and secondary valves. The aspiration port can be aspirated to remove bubbles to reduce risk of air entrainment. Aspiration can be used in addition to, or as a replacement for internal volume expansion in the compound valve system. 
     Reference will now be made in detail to examples of the disclosed technology, such as those illustrated in the accompanying drawings. Wherever convenient, the same references numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG.  1    illustrates an example sheath introducer assembly  100  including a secondary valve accessory device  160  and a sheath introducer  110 . The secondary valve accessory device  160  is illustrated detached from the sheath introducer  110 . The secondary valve accessory device  160  can be manufactured separately from the sheath introducer  110  and subsequently attached by a user (e.g., physician or other health care provider). As illustrated, the secondary valve accessory device  160  can include latch extensions  166  configured to snap onto a ridge  114  at a proximal end  116  of a handle  112  of the sheath introducer  110 . Additionally, or alternatively, the secondary valve accessory device  160  and the sheath introducer  110  can be assembled together by other suitable mechanical attachment mechanism (e.g., interference fit, screw threads, double sided tape, adhesive, etc.) as understood by a person skilled in the pertinent art. Alternatively, a secondary hemostatic valve assembly  162  similar to that of the illustrated secondary valve accessory device  160  can be integral to the sheath introducer  110 . 
     The sheath introducer  110  can be configured similarly to introducers known in the art. The sheath introducer  110  can be deflectable such as described in U.S. Pat. No. 10,046,141 incorporated herein by reference and attached in the Appendix of priority application U.S. 63/272,722, a CARTO VIZIGO® Bi-Directional Guiding sheath by Biosense Webster, and/or a MOBICATH® Sheath by Biosense Webster. Alternatively, the sheath introducer can be fixed similar to a CARDIAGUIDE™ Fixed Sheath by Biosense Webster. The sheath introducer  110  can have an identical structure to known sheath introducers, or a structure similar to known sheath introducers that is modified to include one or more mating features  114  such as, but not limited to, a ridge and/or threads to facilitate attachment. 
     The sheath introducer  110  can include a primary hemostatic valve assembly  130  having a primary valve opening  132 . The primary valve opening can be sized to receive an intralumenal device  150  (see  FIG.  2   ) to facilitate catheter based diagnostics and/or treatments (e.g., mapping, ablation, etc.). The sheath introducer  110  can include a side port  134  similar to some known sheath introducers. The sheath introducer  110  can include an electrical connector  118  similar to some known sheath introducers. 
     The secondary valve accessory device  160  can include a secondary valve opening  164  that aligns to the primary valve opening  132  of the sheath introducer  110  when the secondary valve accessory device  160  is attached to the sheath introducer  110 . The secondary valve accessory device  160  can include an inner housing  182  having a funnel shape that can function as an introducer tool for an intralumenal device. The secondary valve accessory device  160  can include an O-ring  168  around an outside surface of the inner housing  182  that is positioned to seal to a proximal end of the primary valve assembly  130  to create an intermediate chamber between the primary seal  136  and the secondary seal  180 . 
       FIG.  2    illustrates an example intralumenal device and secondary valve assembly  102  including an intralumenal device  150  and the secondary valve accessory device  160 . The intralumenal device  150  can include a catheter shaft  152  and an end effector  154 . The intralumenal device  150  can be configured similar to any number of known devices including catheters for diagnostics and/or treatments. The end effector  154  can have a diameter D 2  that is larger than a diameter D 1  of the catheter shaft  152 . For instance, the end effector  154  can include spine(s), lasso(s), balloon(s), and other such structures. The end effector  154  may be collapsed for delivery through the primary valve opening  132  of the sheath introducer  110  and can be configured to expand upon exiting a distal end of the sheath introducer  110 . 
     For the sake of illustration, the end effector  154  is shown extending distally from the secondary valve accessory device  160 . In practice, the end effector  154  can be positioned within the inner housing  182  (see  FIG.  1   ) prior to attachment of the secondary valve accessory device  160  to the sheath introducer  110 , and the inner housing  182  can function as an introducer tool that aids insertion of the end effector  154  through the primary valve opening  132  and into the sheath introducer  110 . The intralumenal device and secondary valve assembly  102  can be pre-assembled for use by a user with the end effector  154  pre-loaded into the inner housing  182 . To use the intralumenal device and secondary valve assembly  102  with the sheath introducer  110 , the user may first attach the secondary valve accessory device  160  to the proximal end  116  of the sheath introducer  110 , then push the catheter shaft  152  distally to move the end effector  154  distally from the inner housing  182  of the secondary valve accessory device  160 , through the primary valve opening  132 , and into an elongated shaft  120  of the sheath introducer (see  FIGS.  3 B and  3 C ). 
     When the intralumenal device and secondary valve assembly  102  is configured as such, the secondary valve opening  164  can be sized smaller than the primary valve opening  132  because the secondary valve opening  164  can be sized to receive the smaller diameter D 1  of the catheter shaft  152  while the primary valve opening is sized to receive the larger diameter D 2  of the end effector  154 . The tighter seal of the secondary valve opening  164  around the catheter shaft  152  can therefore reduce risk of leak and air entrainment compared to a system in which all seal(s) must be sized to accommodate the larger diameter D 2  of the end effector  154 . 
     The secondary valve accessory device  160  can further be configured to detach from the sheath introducer  110  so that subsequent intralumenal devices can be inserted into the sheath introducer  110 . 
       FIG.  3 A  illustrates a side view of a proximal end of the example sheath introducer assembly  100  with the secondary accessory device  160  attached to the sheath introducer  110 . The illustration shows the side port  134  rotated to the forefront. 
       FIG.  3 B  illustrates a cross-sectional view of the example sheath introducer assembly in a plane perpendicular to the plane of the page as indicated in  FIG.  3 A . 
       FIG.  3 C  illustrates a cross-sectional view of the example sheath introducer assembly in a plane parallel to the plane of the page as indicated in  FIG.  3 A . 
     Referring collectively to  FIGS.  3 B and  3 C , the sheath introducer assembly  100  includes an intermediate chamber  140  between a secondary seal  180  of the secondary hemostatic valve assembly  162  and a primary seal  136  of the primary hemostatic valve assembly  130 . The sheath introducer assembly  100  also includes a chamber  138  on the distal side of the primary seal  136  that leads distally to a lumen  122  of the elongated shaft  120  of the sheath introducer  110 . The intermediate chamber  140  can be bound by the secondary seal  180 , the primary seal  136 , and the inner housing  182  of the secondary valve accessory device  160 . The intermediate chamber  140  can be fluidically sealed, by the secondary seal  180  and the inner housing  182 , from an external environment. The intermediate chamber  140  can be fluidically sealed, by the primary seal  136 , from the chamber  138  on the distal side of the primary seal  136 . 
     As illustrated in  FIG.  3 B , the side port  134  is in fluidic communication with the chamber  138  on the distal side of the primary seal  136 , and thereby the side port  134  is in fluidic communication with the lumen  122  of the elongated shaft  120 . Although not illustrated, the sheath introducer assembly  100  can further include a secondary side port in fluidic communication with the intermediate chamber  140 . The secondary side port can be configured similarly to the side port  134  of the sheath introducer  110  to allow aspiration of the intermediate chamber  140 . In some examples including the secondary side port, the side port  134  of the sheath introducer  110  can be optional. The secondary side port can be integral to the secondary valve accessory device  160 . 
       FIG.  4    illustrates an exploded view of the secondary valve accessory device  160  modified so that the secondary seal  180  is able to move in the direction of the longitudinal axis L-L (“longitudinally”) in response to a pressure differential between the intermediate chamber and an external environment, wherein the secondary valve  180  is positioned between the intermediate chamber  140  and the external environment.  FIGS.  3 B and  3 C  illustrate a stationary secondary seal  180 . The stationary secondary seal  180  is simpler to manufacture and may be sufficient to reduce leakage and/or entrainment in many treatment methods. The movable secondary seal  180  may provide additional pressure dampening in treatment methods which typically result in larger pressure differentials. The secondary valve accessory device  160  illustrated in  FIGS.  4  through  6    can be used in place of the secondary valve accessory device  160  illustrated in  FIGS.  3 B and  3 C . 
     Referring to  FIG.  4   , the secondary hemostatic valve assembly  162  can include a proximal retainer ring  172 , one or more springs  174 , a proximal washer  176 , the secondary seal  180 , a distal washer  178 , and the inner housing  182 . The inner housing  182  can include a seal chamber  184  and a tubular extension  186 . The seal chamber  184  can have an inner diameter D. The tubular extension  186  can include a funnel taper at its proximal end that opens to the seal chamber  184 . The funnel taper can be shaped to guide an intralumenal device toward the longitudinal axis L-L. 
     The secondary valve accessory device  160  can include a housing  170  providing structural support for the secondary hemostatic valve assembly  162 . As in the previous illustrations, the housing  170  can be configured to attach to the sheath introducer  110 . Alternatively, the housing  170  can be integral to the sheath introducer  110 . 
       FIG.  5    illustrates a cross-sectional view of the secondary hemostatic valve assembly  162  of  FIG.  4    in which the secondary seal  180  is in a first position. The secondary seal  180  is secured between the proximal washer  176  and the distal washer  178 . The springs  174  extend between the proximal retainer ring  172  and the proximal washer  176  to press the distal washer  178  against a distal surface of the inner housing  182  within the seal chamber  184 . The external environment is at an ambient pressure P 0 , and the intermediate chamber  140  is at an internal pressure P 1 . When the secondary seal  180  is in the first position, the pressure differential from the intermediate chamber to the external environment does not provide sufficient force on the secondary seal  180  to cause the springs  174  to compress. 
       FIG.  6    illustrates a cross-sectional view of the secondary hemostatic valve assembly  162  of  FIG.  4    in which the secondary seal  180  is in a second position. The intermediate chamber  140  is at an increased pressure P 2  such that the pressure differential from the intermediate chamber to the external environment provides sufficient force to cause the springs  174  to compress to their fullest extent. The spring force can be tailored to cause the secondary seal  180  to move from the first position to the second position, and a contiguous range of positions therebetween, as a function of pressure differential between the intermediate chamber  140  and the external environment as understood by a person skilled in the pertinent art. 
     The secondary seal  180  is translated a length L 1  upon moving from the first position to the second position. The translation of the secondary seal  180  increases the internal volume of the intermediate chamber  140  by a volume that can be calculated as cross-sectional area of the seal chamber  184  times the translated length L 1 , where the change in internal volume can be equal to pi×(½ D) 2 ×L 1  for a cylindrical seal chamber  184 . The increase in volume of the intermediate chamber  140  can be effective to decrease the pressure within the intermediate chamber, and thereby reduce risk of leakage through the secondary valve opening  164 . The amount of pressure relieved is a function of increase in internal volume of the intermediate chamber  140  where the greater the change in volume, the greater the amount of pressure relieved. 
     Pressure damping is therefore determined by spring force and change in internal volume of the intermediate chamber  140 . The spring stiffness and/or change in internal volume can be designed to damp a specific pressure profile related to manipulating of a specific intralumenal device through a specific sheath. For instance, an intralumenal device having a large balloon end effector may result in higher pressure differentials compared to a an intralumenal device having a smaller end effector or an end effector with spines when delivered through the same sheath introducer, and the same intralumenal device delivered through a smaller sheath introducer may result in higher pressure differentials compared to the same intralumenal device delivered through a larger sheath. The spring force and volume can be increased for higher pressure differentials and decreased for lower pressure differentials. 
     The chamber  138  on the distal side of the primary seal  136  (see  FIGS.  3 B and  3 C ) can be at a third pressure. The third pressure can be the same or different from the pressure of the intermediate chamber  140 . In some examples, the primary valve opening  132  can be larger than a primary valve opening of a sheath introducer lacking the secondary hemostatic valve assembly  162  for comparable treatment methods because the secondary hemostatic valve can compensate for leakage and/or entrainment through the primary valve opening  132 . In some examples, a larger primary valve opening  132  may be desirable to accommodate a large end effector. Therefore, some fluidic exchange between the intermediate chamber  140  and the chamber  138  on the distal side of the primary seal  136  can be tolerated, which can result in reduced pressure differential between the intermediate chamber  140  and the chamber  138  on the distal side of the primary seal  136 . 
       FIG.  7    illustrates the sheath introducer assembly  100  and intralumenal device  150  in use. A user  10  is manipulating the intralumenal device  150  which is inserted through the compound valve assembly of the sheath introducer assembly  100 . The user  10  is in an external environment at a pressure P 0 . When retracting the intralumenal device  150  from the sheath introducer assembly  100 , the compound valve can reduce likelihood of outward leaks due to accumulation of pressure within the sheath introducer  110  compared to operation of a similar system lacking the secondary hemostatic valve assembly  162 . In some treatments in which the intralumenal device has a large or uniquely shaped end effector, the compound valve can reduce likelihood of air entrainment when the end effector breaches the primary seal compared to operation of a similar system lacking the secondary hemostatic valve assembly  162 . In some treatments, the compound valve can be effective to reduce leakage when pressure within the chamber  138  on the distal side of the primary seal  136  measures from about  10  to about  15  pounds per square inch (psi) when measured through the side port  134 . 
       FIG.  8 A  illustrates another example secondary valve accessory device  260 . 
       FIG.  8 B  illustrates a cross-sectional view of the secondary valve accessory device  260  as indicated in  FIG.  8 A . The secondary valve accessory device  260  illustrated in  FIGS.  8 A and  8 B  can be configured similarly to the secondary valve accessory device  160  illustrated in  FIGS.  1  through  6   . The secondary valve accessory device  260  illustrated in  FIGS.  8 A and  8 B  includes a housing  270  having threads  217  rather than latch extensions  166  as illustrated in  FIGS.  1  through  3 C . The secondary valve accessory device  260  illustrated in  FIGS.  8 A and  8 B  can therefore be screwed onto a sheath introducer configured similarly to the sheath introducer  110  illustrated in  FIGS.  1  through  3 C  but for having screw threads in place of the ridge  114 . 
     The secondary valve accessory device  260  illustrated in  FIGS.  8 A and  8 B  includes a secondary hemostatic valve assembly  262  including a proximal retainer ring  272 , an inner housing  282 , and an O-ring  268 . The secondary valve assembly  260  can further include a stationary secondary seal similar to as illustrated in  FIGS.  3 B,  3 C  or a movable secondary seal positioned within a seal chamber  284  of the inner housing  282  similar to as illustrated in  FIGS.  4 ,  5 , and  6   . The inner housing  282  can further include a tubular extension  286 . The length of the tubular extension  286  can be sized to fit an end effector of predetermined size so that the secondary valve accessory device  260  can be integrated with an intralumenal device similar to the intralumenal device and secondary valve assembly  102  illustrated in  FIG.  2   . 
       FIG.  9    illustrates a cut-away view of an example sheath introducer assembly  200  including the secondary valve accessory  260  illustrated in  FIGS.  8 A and  8 B  and a sheath introducer  210  having a threaded proximal end and a side port  234 . The sheath introducer assembly  200  can function and be configured similarly to the sheath introducer assembly  100  illustrated in  FIGS.  1  through  7    and described elsewhere herein. 
     The descriptions contained herein are examples of embodiments of the invention and are not intended in any way to limit the scope of the invention. As described herein, the invention contemplates many variations and modifications of system components, including alternative combinations of components illustrated in separate figures, alternative materials, alternative component geometries, and alternative component placement. Modifications and variations apparent to those having skilled in the pertinent art according to the teachings of this disclosure are intended to be within the scope of the claims which follow.