Patent Publication Number: US-6221057-B1

Title: Hemostasis valve, system and assembly

Description:
This application is a Divisional of application Ser. No. 08/735,521, filed Oct. 23, 1996, which application is incorporated herein by reference, now U.S. Pat. No. 5,895,376. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to hemostasis valves used in diagnostic, therapeutic and interventional vascular procedures, and more particularly to the sealing mechanisms in such devices and to related systems, including those for flushing. 
     BACKGROUND OF THE INVENTION 
     Hemostasis valves (also sometimes referred to as “Y-connectors” and “Touhy-Borst valves”) are commonly used in certain medical procedures. A guide catheter is connected to the distal end of the valve, and an operating instrument, such as a guide wire or balloon catheter, is inserted into the proximal end and through the guide catheter to the desired location in the patient. After the operating instrument is in place, the valve is closed to keep blood from leaking out of the patient (“hemostasis”). 
     One of the problems with current hemostasis valves is that they are cumbersome to operate, taking a long time to open and close. Most employ a Touhy-Borst sealing mechanism such as that described in U.S. Pat. No. 4,886,507. A threaded cap deforms an O-ring into a tapered opening until the O-ring clamps down on the operating instrument. Each time the operating instrument is adjusted, the cap must be unthreaded before and then rethreaded after the manipulation. During the time that the valve is open, blood leaks from the patient and/or contrast media is lost. Inaccurate blood pressure readings also occur. There is also a risk of air emboli when the valve is open, particularly when removing the operating instrument. 
     Another problem with prior art hemostasis valves, such as Touhy-Borst valves, is that significant mechanical force must be applied to the operating instrument in order to maintain the seal. This is particularly a problem at higher system pressures, and when pressure spikes occur, such as when flushing the system with saline or introducing contrast media. The often delicate drive shaft of the operating instrument can be crushed by the force of the seal. The high force seal also prevents moving the operating instrument while the valve is closed. 
     One attempt at addressing some of these problems is shown in the &#39;507 patent. In addition to a Touhy-Borst, this design includes a membrane having a fixed circular opening for sealing shafts within a certain diameter range. This sealing arrangement, however, still relies solely on a mechanical sealing system which requires high shaft forces at high system pressures. It also incorporates the same threaded Touhy-Borst valve, which requires the cap to be manually threaded in order to close the valve. The fixed opening membrane would also be helpful only with operating instruments in a particular diameter range. 
     Hemostasis systems typically have a perfusion port used to flush the system with saline in order to prevent blood clots from being formed. This is done by a technician periodically during the procedure, which takes time and may interrupt the procedure. The blood pressure readings are also inaccurate during the flush. 
     What has been needed is a hemostasis valve which opens and closes easier, maintains a seal at higher pressures without damaging the instrument, and permits movement of the instrument while maintaining a seal. What has also been needed is a hemostasis system which reduces or eliminates the need for periodic flushing. What has also been needed is a hemostasis assembly which reduces blood loss and the risk of air emboli while the valve is open. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a hemostasis valve, system and assembly are provided. The inventions can be used in a variety of diagnostic, therapeutic and interventional procedures, including angiography, angioplasty, stent placement, drug infusion, intravascular ultrasound, rotablation, and atherectomy. 
     In one aspect of the invention, a hemostasis valve comprises a valve body having a proximal end for receiving an operating device, a distal end for connection to a guide catheter, and a through-lumen in the valve body intermediate the proximal and distal ends. The operating device is inserted through the through-lumen and into the guide catheter. A chamber in the valve body surrounds the through-lumen and is filled with fluid under pressure. A collapsible membrane in a portion of the through-lumen is constructed and arranged such that the fluid pressure in the chamber assists in sealing the collapsible membrane around the operating device. 
     In another aspect of the invention, a hemostasis valve comprises a valve body having a proximal end for receiving an operating device, a distal end for connection to a guide catheter, and a through-lumen in the valve body intermediate the proximal and distal ends. The operating device is inserted through the through-lumen and into the guide catheter. The through-lumen comprises a proximal portion, a distal portion and an elastomeric sleeve therebetween. One of the proximal and distal portions of the through-lumen is rotatable relative to the valve body between a closed position wherein the elastomeric sleeve is twisted to seal around the operating device and an open position wherein the elastomeric sleeve is sufficiently untwisted to unseal the elastomeric sleeve from the operating device. 
     In another aspect of the invention, a system for flushing a vascular catheter comprises a hemostasis valve and a vascular catheter for insertion into a patient, sealingly connected to the hemostasis valve. A source for providing flushing fluid under pressure is in fluid communication with the hemostasis valve. A mechanism controls the flow of said flushing fluid from the source to the hemostasis valve at a rate of about between 0.10 to 10.0 cubic centimeters per minute, thereby continuously flushing the vascular catheter. 
     In another aspect of the invention, a hemostasis valve assembly comprises a hemostasis valve which is moveable between a closed position wherein liquid in fluid communication with a patient is sealed and an open position. An expandable reservoir in fluid communication with the liquid in the hemostasis valve is moveable between expanded and retracted positions. The expandable reservoir is constructed and arranged such that, when the hemostasis valve is moved to the open position, the expandable reservoir retracts toward the retracted position so as to force liquid out of the open hemostasis valve. 
     These and other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto. However, for a better understanding of the invention and its advantages, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter in which there is illustrated and described preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross-sectional view of a first embodiment of a hemostasis valve according to the present invention, including a system for continuously flushing a vascular catheter and an expandable reservoir; 
     FIG. 2 is a cross-sectional view of a second embodiment of a hemostasis valve according to the present invention; and 
     FIG. 3 is a perspective view of the clamp used in the hemostasis valve of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, wherein like numerals designate like parts, first and second hemostasis valve embodiments are shown in FIG.  1  and FIGS. 2-3, respectively. The hemostasis valves of the present invention can be used with a variety of diagnostic, therapeutic, and interventional operating devices as set forth above. 
     Referring to the first embodiment shown in FIG. 1, hemostasis valve  10  comprises valve body  12  with proximal end  14  for receiving operating device  19  and distal end  16  for connection to guide catheter  18 . A standard hose barb  15  is shown at proximal end  14  and a standard luer lock  17  is shown at distal end  16  for connection to guide catheter  18 . 
     Valve body  12  includes through-lumen  20  through which operating device  19  is received. In a portion of through-lumen  20  is a collapsible membrane  22  which seals around operating device  19 . This sealing is assisted by fluid pressure from chamber  30  surrounding through-lumen  20 . This pressure assist is advantageous in a number of ways. The lower pressure differential between through-lumen  20  and chamber  30  makes it easier to create a seal by mechanically deforming collapsible membrane  22 . Less mechanical force is consequently necessary for sealing, which reduces the risk of damaging the drive shaft of the operating device and helps permit manipulation of operating device  19 , longitudinally and torsionally, while maintaining a seal. 
     In the first embodiment of FIG. 1, chamber  30  is in fluid communication with through-lumen  20  through passage  32 . Thus, for example saline or the patient&#39;s blood can pass back and forth. This arrangement is particularly helpful in dynamic high pressure situations because the high pressure tending to open the hemostasis valve is offset by the also high pressure in chamber  30 . 
     Collapsible membrane  22  is mechanically deformed in the first embodiment by turning adjustment knob  40  so as to twist elastomeric sleeve  44  around operating device  19  to effect a seal. Adjustment knob  40  is biased toward the closed position (shown) by coil spring  46  around valve body  12  which is connected at its opposite end to stationary knob  42 . It will be understood that a variety of other spring mechanisms could be employed for this purpose. This arrangement permits better sensitivity when opening valve as well as automatic closure, which reduces the time that the valve is open. 
     Elastomeric sleeve  44  is fixedly and sealingly disposed onto barbs  41 ,  43  of adjustment and stationary knobs  40 ,  42 . Sleeve  44  is preferably made of a flexible biocompatible material such as silicone or latex. The preferred sleeve has a {fraction (3/16)} inch o.d., ⅛ inch i.d., and a length (measured between barbs  41 , 43 ) between 0.25 and 0.50 inches. To help facilitate movement of operating device  19  while maintaining the valve closed, it would be preferable to coat the inner side of sleeve  44  with for example a hydrogel to provide a slicker surface. 
     Referring to FIGS. 2 and 3, a second preferred embodiment of a hemostasis valve is shown. In describing the second embodiment, attention will be focused to the relevant differences from the first embodiment. 
     In the second embodiment, chamber  30  is not in fluid communication with through-lumen  20 , but is instead isolated. Saline or other fluid is provided to chamber  30  by high pressure fluid source  50  through port  51 . Second port  52  is used to evacuate air or relieve pressure from chamber  30  with valve  53 . In this way, opening and closing of the hemostasis valve can in fact be accomplished solely by selectively providing sufficient fluid pressure in chamber  30  to completely seal collapsible membrane  22  around operating device  19 . A third port (not shown) communicating with through-lumen  20  could be used for pressure monitoring, flushing, and/or injecting contrast media for example. The fluid pressure in chamber  30  is preferably at least that in through-lumen  20 . A more simple arrangement than the second preferred embodiment would eliminate both ports  51 ,  52  and have a constant pressure in chamber  30  sufficient to assist in sealing collapsible membrane  22  around operating device  19 . 
     Collapsible membrane  22  is mechanically deformed by action of feet  61  of clamp  60 , best shown in FIG.  3 . As with the first embodiment, a spring  62  (here a compression spring) is used to bias the valve to a closed position. Feet  61  extend into correspondingly shaped openings  57  in rigid outer wall  56  and deform outer elastomer tube  54  radially inward. This increases the fluid pressure in chamber  30  which in turn deforms collapsible membrane  22  to seal around operating device  19 . Both membrane  22  and tube  54  are preferably made of latex. Membrane  22  has a {fraction (3/16)} inch i.d. and is 0.012 inches thick. Tube  54  has a ⅜ inch i.d. and is 0.085 inches thick. They could also be made of silicone or urethane, but a thinner wall for tube  54  would likely be required. It will be understood that a variety of other mechanisms could be used to radially direct pressure and that mechanical pressure could be applied directly to collapsible membrane  22  alone or in combination with fluid pressure to effect a seal. 
     Referring now to FIG. 1, system  70  provides a continuous flush of guide catheter  18  and hemostasis valve  10 . Saline is delivered to hemostasis valve  10  through first port  75  at a rate of about 0.1 to 10.0 cubic centimeters per minute, preferably about 1.0 cubic centimeters (1 ml.) per minute. High pressure saline is supplied by source  71 , which is preferably a saline bag at a pressure of about 300 millimeters of mercury. The desired flow rate can be achieved by a variety of flow restricting arrangements. The preferred arrangements are an appropriately sized orifice  72  and/or capillary tube  73 . The preferred capillary tube  73  is 30 gauge hypotube 0.6 inches long and having an i.d. of 0.006 inches. System  70  permits more continuous monitoring of pressure with pressure monitor  92  by reducing or possibly eliminating the need for flushing with high pressure saline  90 . 
     Referring again to FIG. 1, hemostasis valve assembly  80  includes bellows  82  which acts as an expandable reservoir of liquid volume. Bellows  82  is connected to hemostasis valve  10  by third port  81 . It is preferably made of an elastomeric material such as latex and should “saturate” (i.e., be substantially expanded) at a mean pressure of about between 60 to 120 millimeters of mercury, most preferably at a typical blood pressure of about 90 millimeters of mercury. It will be appreciated that a variety of expandable reservoir arrangements other than a bellows could be suitable for this purpose, as for example one that relies on springs or another mechanism instead of the inherent elasticity of the reservoir. 
     The liquid volume stored by expandable reservoir  82  under pressure has a number of advantages. It reduces blood loss when hemostasis valve  10  is opened by replacing lost liquid with liquid from the retracting reservoir instead of blood from the patient. There is also a significant risk of air emboli caused by the vacuum which is created when the distal end of operating device  19  is pulled out of proximal end  14  of hemostasis valve  10 . Expandable reservoir  82  helps force liquid out of proximal end  14  of hemostasis valve  10  so as to prevent air from entering. Expanding reservoir  82  is also helpful when hemostasis valve  10  is closed. For example, it will tend to absorb pressure spikes, such as those created by high pressure flushing  90  or injecting contrast media  94 , by reservoir expanding instead of liquid leaking out of hemostasis valve  10 . 
     It should be understood that the present invention is not limited to the preferred embodiments discussed above which are illustrative only. Changes may be made in detail, especially in matters of shape, size, arrangement of parts, or material of components within the principles of the invention to the full extent indicated by the broad general meanings of the terms in which the appended claims are expressed.