Abstract:
A hemostasis valve for use in introducing an over-the-wire medical lead into a patient&#39;s vascular system comprises a housing with a passageway, the passageway including an elastomeric pierceable seal member interposed therein and a resilient, annular tip surrounding a distal end of the housing where the tip has a central opening that is sized to receive a tubular connector terminal at the proximal end of the medical lead for dripping the end of the lead and sealing the lead&#39;s tubular connector terminal in the passageway of the housing.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to apparatus for facilitating placement of an over-the-wire, left ventricular lead in a patient, and more particularly to a hemostasis valve for creating a fluid-tight seal with a proximal lead terminal of a left ventricular pacing lead and with a guidewire used during a lead implant procedure. 
     II. Discussion of the Prior Art 
     In treating heart failure patients with cardiac stimulation, it is necessary to install a stimulating/sensing lead on the left side of the heart. However, placement of the lead itself into the left ventricle is to be avoided. A procedure has been perfected for advancing a very small diameter lead through the coronary sinus and down a coronary vein on the left side of the heart whereby electrical stimulation of myocardial tissue of the left ventricle can be achieved. Because the lead must necessarily be of a small diameter and be highly flexible, it lacks steerability. Therefore, a guidewire is used to facilitate routing of the lead. The guidewire is advanced through the vascular system until its distal end enters the target coronary vein. The stimulating lead is tubular in configuration, allowing it to be slipped over the guidewire and advanced by pushing until its distal electrode(s) are at a desired location on the left ventricle. 
     In that the lead is tubular, blood can flow through its lumen and if clotting occurs, it may prove difficult to extract the guidewire without dislodging the lead. If blood is allowed to exit the proximal end of the lead, it can create a mess for the surgeon or cardiologist to deal with. 
     Accordingly, there is a need for a hemostasis valve that can be used to prevent blood or other fluid loss during lead implant procedures involving over-the-wire cardiac stimulating leads and which can be used to prevent clotting in the lumen of the lead. 
     The prior art discloses a variety of catheter introducers incorporating hemostasis valves, whereby blood loss along the outside diameter of a guidewire or diagnostic or angioplasty catheter is prevented. The Stevens U.S. Pat. Nos. 5,693,025 and 5,935,112 are exemplary. They each include a resilient rubber seal member having an aperture therethrough for receiving a guidewire and a collar that when screwed down on the proximal end of the device compresses the seal member tightly against the guidewire. A further collet-like clamp is provided at the distal end of the Stevens&#39; introducer to provide a way of clamping the device in place on a proximal end of a catheter. The introducer of the prior art Stevens patent also includes provision for introducing a fluid or some other medical device into the patient&#39;s body. 
     U.S. Pat. No. 6,142,981 to Heck et al. describes a cannula having a hemostasis valve thereon that incorporates an elastomeric seal having a self-closing aperture which, when forced open by a guidewire or the like, seals about the guidewire to prevent blood loss therealong. No provision is made for clamping the distal end of the cannula to a catheter or stimulating lead. Thus, the device described in the Heck &#39;981 patent is similar in most respects to the hemostasis cannula valve described in the Stevens U.S. Pat. No. 5,643,227 and the Davila et al. U.S. Pat. No. 5,520,655. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a hemostasis valve for use in introducing an over-the-wire medical lead into a subject&#39;s vascular system. An over-the-wire lead comprises a lead body with a distal end, a proximal end and a lumen that extends between the two ends. Affixed to the proximal end of the lead body is a tubular connector terminal that is adapted to mate with contacts in the header of a cardiac rhythm management device, such as a pacemaker or defibrillator. The hemostasis valve itself comprises a molded plastic housing having a passageway therein with first and second openings in communication with the passageway. An elastomeric, pierceable, seal member is carried by the housing for sealing the first opening. A resilient annular tip surrounds the second opening and it itself has a central opening sized to receive the tubular connector terminal at the proximal end of the lead body therein with a predetermined friction fit for both gripping and sealing the tubular connector terminal with respect to the housing. This design obviates the need for a screw-type clamp at opposed ends of the housing, one for establishing a seal to the guidewire and the other for establishing a seal to the lead&#39;s tubular connector terminal. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. 
     FIG. 1 is an exploded perspective view showing an over-the-wire pacing lead assembled on to a guidewire and the hemostasis valve assembly comprising a preferred embodiment of the present invention; 
     FIG. 2 is an enlarged side elevational view of the hemostasis valve assembly without the side port three-way stopcock; and 
     FIG. 3 is an exploded side elevational view of the hemostasis valve assembly. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown an over-the-wire cardiac stimulating lead  10  disposed on an elongated guidewire  12 . The lead  10  includes an elongated flexible elastomeric lead body  14  having a proximal end  16 , a distal end  18  and a lumen  20  that extends all the way from the proximal end to the distal end. One or more electrodes as at  22  and  24  are provided on the surface of the lead body  14  in a distal zone of the lead  10 . Affixed to the proximal end  16  of the lead body  14  is a tubular lead connector terminal  26  which is adapted to be inserted into a connector bore in a header of a cardiac rhythm management device, such as a pacemaker or an automatic implantable cardiac defibrillator. The tubular connector  26  includes contacts, as at  28 , that are connected by wires (not shown) that extend the length of the lead body and make an electrical connection to the electrodes  22  and  24  on the distal end portion of the lead. The tubular connector  26  is open at its proximal end  30  allowing the guidewire  12  to pass through the connector terminal  26 , down the length of the lead body  14  and out its distal opening  20 . 
     With continued reference to FIG. 1, it is seen there that there is also a hemostasis valve assembly that is indicated generally by numeral  32 . It comprises a molded plastic housing  34  having a distal end  36  and a proximal end  38 . The housing  34  defines a passageway  40  (FIG. 2) from one end to the other. An elastomeric seal member  42  is contained within a proximal cap  44  that is bonded to the proximal end  38  of the housing  34 , preferably in an ultrasonic welding operation. 
     The seal  42  comprises a cylindrical block of elastomeric material having opposed conically shaped recesses  46  and  48  formed inwardly and with a fine pinhole  50  extending between the apices of the opposed conical recesses  46  and  48 . The proximal end cap  44  has a top surface  52  with a frustoconical aperture  54  formed therethrough in general alignment with the recesses  46  and  48  which lie on a longitudinal axis of the assembly  32 . It can be seen, then, that when the cap  44  containing the elastomeric seal member  42  is joined to the body member  34 , the elastomeric seal  42  blocks the opening  58  at a first end of the passageway  40  through the housing  34 . 
     Without limitation, the seal member  42  may be fabricated from polyisoprene and because of the self-closing pinhole  50  formed therein, the guidewire  12  may readily penetrate through the seal member with the polyisoprene material forming a lip seal against the guidewire preventing the flow of blood or saline beyond the seal element. 
     Over molded onto the polycarbonate housing  34  is a resilient annular tip, preferably, but not necessarily, formed of polyurethane. The resilient annular tip is identified by numeral  58  in FIGS. 1 and 2. In order to positively retain the over-molded resilient annular tip  58  on the housing  34 , an annular groove  60  is formed inwardly from the exterior surface thereof to create a flange  62 . When the polyurethane tip  58  is over-molded onto the distal end of the housing  34 , it flows into the groove  60  and about the flange  62 . The inner diameter of the bore  64  in the annular polyurethane tip  58  is designed to be slightly less than the outside diameter of the tubular connector terminal  26  with which the hemostatic valve  32  is used. Thus, the annular tip member  58  not only clamps on to the proximal end of the tubular connector terminal when it is forced into the bore  64 , but the close fit also creates a fluid-tight seal about the outer surface of the tubular connector terminal  26 . 
     Integrally formed with the housing  34  is a Y-branch  66  having a bore  68  comprising a flushing port that is in fluid communication with the passageway  40  and a counterbore  70 . Referring to FIG. 3, there is shown a length of plastic tubing  72  fitted into the counterbore  70 . Attached to the other end of the tube  72  is an outlet port of a three-way stop-cock assembly indicated generally by numeral  74 . The stop-cock assembly has an actuating lever  76  for rotating a ball valve member (not shown) where that ball valve member has two radial bores formed that intersect therethrough at a right angle. A lure fitting  78  comprising a first inlet port allows the stop-cock assembly to be coupled to a fluid-filled syringe (not shown). When the lever  76  is turned, such that one bore in the ball valve is longitudinally aligned with the lure fitting  78  and the tube  72 , a flushing fluid can be ejected from the syringe, through the tube  72  and the bore  68  into the passageway  40  leading to the lumen in the lead terminal connector  26  and the lumen in the lead body  14  itself. 
     When the stop-cock lever is rotated 90°, a second inlet port  80  is made to be in fluid communication with the tube  72  so that a second fluid, for example, an anti-coagulant, can be introduced into the fluid that is made to pass through the hemostatic valve assembly and the lead, thereby inhibiting clotting that might otherwise make it difficult to remove the guidewire  12  from the lead without displacing the electrodes  22  and  24  on the lead from their target location on the left side of the heart. 
     It can be seen, then, that the hemostasis valve of the present invention is indicated for maintaining a seal around the terminal connector of a lead at the distal end of the valve assembly and around a guidewire at the proximal end during lead lumen flushing and implant procedures. To facilitate penetration of the elastomeric seal member  42  by the supple tip of an atraumatic guidewire, there is also provided a wire guide member  82  (FIG.  1 ). The wire guide member  82  is funnel-shaped, having a tubular stem  84  and a cone-shaped head  86  at its proximal end. The wire guide member  82  is preferably molded from a medical-grade plastic and is relatively rigid. As such, the tubular stem  84  thereof may be forced through the pinhole slit  50  in the seal member  42  and the funnel head  86  acts to direct the tip of the guidewire through the wire guide member into the passage  40  of the hemostatic valve assembly  32  and from there, down the lumen of the lead. 
     It can be seen, then, that by this invention there is provided a hemostasis seal that allows movement of a guidewire into and out of the vasculature, catheter and lead lumen with substantially no fluid loss. The seal assembly also allows for easy penetration and introduction of the wire guide member  82  through the seal which, in turn, accommodates the introduction of the floppy end of the guide wire through the wire seal. Moreover, sealing is achieved without the need to rotate an end cap as in prior art designs. Further, because of the design of the tip member  58 , it is not necessary to provide a collet-type clamp to affix the hemostatic seal assembly to the lead&#39;s terminal pin. 
     This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself