Abstract:
Methods and apparatus are provided for closing incisions within biological tissue. In one embodiment, a device and method are provided for suturing biological tissue, such as, for example, an organ or blood vessel. The suturing apparatus is particularly well suited for suturing an incision made in an artery, such as the femoral artery, following a catheterization procedure. The device eliminates the need to apply pressure to a patient&#39;s thigh for an extended period of time, and eliminates many of the complications and costs associated with the creation of a thrombus patch. In addition, the device comprises an improved handle portion which enables the physician to quickly and easily apply suture. The handle portion is very reliable and easy to manipulate. The suturing may be used in combination with existing catheter sheath introducers.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 11/235,751, filed Sep. 27, 2005, which claims the benefit of U.S. Provisional Application No. 60/613,636, filed Sep. 27, 2004, the entirety of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to a suturing apparatus. More specifically, the invention relates to a device and method for applying suture within biological tissue that may not be directly accessible to the physician. 
     2. Description of the Related Art 
     Physicians frequently use suture to close cuts, punctures, incisions and other openings in various biological tissue, such as blood vessels, of the human body. 
     In an arterial catheterization procedure, a relatively small percutaneous incision is made in the femoral or other artery. A catheter is inserted through the incision and directed along an arterial path to a target area, such as the heart, to perform one or more procedures, such as an angioplasty or angiogram. These procedures are intended to be relatively quick ‘outpatient’ procedures. 
     Upon completion of the catheterization procedure, the physician typically creates a ‘thrombus patch’ by applying direct pressure to the patient&#39;s thigh to make the blood around the incision clot. It is very important that the applied pressure does not impede the flow of blood through the femoral artery. As a result, it is commonplace for the physician to apply direct pressure by hand for the first twenty minutes after the procedure. During this time, the physician can feel the pulse to assure the artery is not occluded. Afterwards, the physician typically transfers responsibility to an assistant who then applies direct pressure using sandbags, clamps or other devices. A significant problem with this approach is that it is frequently necessary to apply the pressure for an extended period of time, such as twenty-four hours or longer. 
     Another problem with the thrombus patch method is that the high blood pressure in the artery can cause the thrombus patch to rupture or burst while direct pressure is being applied to the thigh or after direct pressure is removed. This requires the entire process to be reinitiated. If the patch ruptures and is not quickly restored, substantial bleeding can occur, with potentially fatal consequences. Because thrombus patches frequently burst, the patient is often kept in the hospital or catheterization lab overnight for observation. As a result, these ‘out-patient’ procedures become ‘in-patient’ procedures, simply because a thrombus patch is often unreliable and/or difficult to create. Staying in the hospital increases patient discomfort and hospital expenses, which are often disproportionate to the actual medical procedure performed. 
     Furthermore, if a thrombus patch cannot be adequately formed, the physician may need to anesthetize the patient and occlude the blood flow to the artery. At this point, the physician is required to make a large incision in the thigh to allow conventional suturing with a needle, suture the artery with conventional means, restore blood flow to the artery, and suture the incision in the thigh. This results in additional discomfort and expenses for the patient. 
     While the above problems could potentially be avoided by suturing the blood vessel immediately following the catheterization procedure, the size and location of the artery make suturing extremely difficult. More specifically, the opening in the thigh is often too small and too deep to provide enough working space for suturing the artery using conventional methods. Thus, in order to suture the vessel using conventional methods, the opening in the thigh would have to be significantly enlarged, thereby further increasing the recovery period and exposing the patient to additional discomfort, undesirable scarring, possible infection and other health risks. 
     SUMMARY OF THE INVENTION 
     Methods and devices are provided for closing incisions within biological tissue. In one embodiment, a device and method are provided for suturing biological tissue, such as, for example, an organ or blood vessel. The device is particularly well suited for suturing an incision made in an artery, such as the femoral artery, following a catheterization procedure. The device eliminates the need to apply pressure to a patient&#39;s thigh for an extended period of time, and eliminates many of the complications and costs associated with the creation of a thrombus patch. In one feature, the device comprises an improved handle portion that allows the physician to apply suture in a quick and efficient manner. The handle portion is very simple to operate, thereby reducing or eliminating the possibility of human error during use. In addition, the actuation mechanisms on the handle portion allow the physician to maintain the device in a steady position while applying suture. 
     In one preferred embodiment, a suturing apparatus comprises an elongate body and an arm mounted to move relative to the elongate body. The arm is formed with a suture mounting portion which mounts an end portion of a suture. The suturing apparatus further comprises a needle having a distal end, wherein the needle is mounted to move relative to the elongate body. A handle is attached to the elongate body and comprises an actuator having a camming surface and a follower having a cammed surface. The follower is connected to move the needle, wherein the camming surface and cammed surface interact in response to movement of the actuator to drive the follower to move the needle. 
     In one variation, the handle has a longitudinal axis, wherein at least a portion of the cammed surface is inclined about 35° or more relative to the axis. In another variation, at least a portion of the cammed surface is inclined about 40° or more relative to the axis. In another variation, at least a portion of the cammed surface is inclined at about 41° relative to the axis. In another variation, at least a portion of the cammed surface is inclined at between about 35-45° relative to the axis. In another variation, at least a portion of the cammed surface is inclined at between about 39-43° relative to the axis. In another variation, at least a portion of the cammed surface is inclined at between about 40-42° relative to the axis. In another variation, the camming surface is curved. 
     In another preferred embodiment, a suturing apparatus comprises an elongate body and an arm is mounted to move relative to the elongate body. The arm has a suture mounting portion which mounts an end portion of a suture. A needle having a distal end is mounted to move relative to the elongate body wherein the distal end of the needle is movable. A handle is attached to the elongate body. The handle comprises an actuator and a follower connected to move the needle by an amount equal to movement of the follower, wherein the amount of movement of the follower is visible to the user. Accordingly, the amount of movement of the needle may be monitored without directly viewing the needle. 
     In one variation, the handle has a housing portion comprised of a transparent material, wherein the follower is visible to the user through the transparent material. In another variation, the needle moves from a start position to a finish position in response to movement of the actuator, wherein the handle includes indicia that at least indicates the position of the follower when the needle is in the finish position. If desired, the indicia may further indicate the position of the follower when the needle is in the start position. In another preferred embodiment, a portion of one or both follower members may be visible and/or extend through the main housing, such that the amount of movement of the needle may be monitored without directly viewing the needle. 
     In another preferred embodiment, a suturing apparatus comprises an elongate body and an arm mounted to move relative to the elongate body. The arm is formed with a suture mounting portion which mounts an end portion of a suture. The suturing apparatus further comprises a needle having a distal end, wherein the needle is mounted to move relative to the elongate body. A handle is attached to the elongate body, the handle comprising an actuator having a camming surface and a follower having a cammed surface. The follower is connected to move the needle such that movement of the follower in a distal direction drives the needle in a distal direction and movement of the follower in a proximal direction drives the needle in a proximal direction. The follower is preferably spring biased towards a proximal direction and has a range of movement. The camming surface and cammed surface interact to drive the follower in a distal direction during at least a substantial portion of the range of movement. 
     In one variation, the actuator has a first finish position, wherein interaction of the cammed surface and camming surface is released in the first finish position such that the spring biasing drives the follower in a proximal direction, thereby automatically retracting the needle in a proximal direction, without retracting the actuator from the first finish position. The actuator may also have a second finish position in which the spring biasing further retracts the needle. The actuator and the follower are relatively configured such that the follower is driven in a proximal direction at a substantially faster rate upon reaching the second finish position than upon reaching the first finish position. 
     In another variation, the actuator has a finish position in which the needle is at a distal end of a range of movement of the needle. The spring biasing of the follower retracts the needle in a proximal direction in response to retraction of the actuator from the finish position. 
     In another preferred embodiment, a method of applying suture to an opening is provided. The method comprises inserting an elongate body into the opening and then extending at least one arm from the elongate body on a distal side of the opening, the at least one arm holding a suture portion. At least one needle is advanced from the elongate body from the proximal side of the opening, through tissue adjacent the opening, and into engagement with the suture portion held by the at least one arm. The needle is advanced by moving an actuator from a first position to a second position and is biased to retract to its first position. The at least one needle is then retracted in a distal to proximal direction, pulling the suture portion proximally through the opening. In one variation, the actuator is depressed to advance the needle. In another variation, the needle retracts by releasing the actuator to return to its first position. In another variation, the needle automatically retracts by further depressing the actuator. In still another variation, the needle is spring biased to return to its first position. 
     In yet another preferred embodiment, a method of applying suture to an opening is provided. The method comprises inserting an elongate body into the opening, the elongate body being connected to a handle having a plurality of actuators. A first actuator is depressed to extend at least one arm from a first position to a second position, the arm in its second position extending from the elongate body on a distal side of the opening, the at least one arm holding a suture portion. A second actuator is depressed to advance at least one needle from the elongate body from the proximal side of the opening, through tissue adjacent the opening, and into engagement with the suture portion held by the at least one arm. The at least one needle is retracted in a distal to proximal direction, pulling the suture portion proximally through the opening and the arm is retracted to its first position. In one variation, a third actuator is depressed to return the at least one arm from its second position to its first position. In another variation, the needle is retracted by returning the second actuator to its initial position. In yet another variation, the needle is spring biased to return to its initial position. 
     In yet another preferred embodiment, a method of advancing a needle comprises providing an actuator capable of being depressed and providing a follower having an angled surface, the follower being connected with the needle and the angled surface being engageable with a surface of the actuator. The actuator is depressed to advance the needle, wherein the distance moved by the needle is proportional to the angle of the angled surface. 
     In yet another preferred embodiment, a method of advancing a needle comprises providing a suturing device having a handle portion and an elongate body, the elongate body having a distal end portion sized for insertion through a vessel wall, the suturing device having two deployable suture arms for holding ends of a suture and two extendable needles for grabbing the ends of the suture from the arms. The elongate body is advanced through an incision in the vessel wall. A first actuator is depressed on the handle portion for deploying the suture arms within the vessel. A second actuator is depressed on the handle portion for extending the needles through the vessel wall for grabbing the ends of the suture from the suture arms. The second actuator is released for withdrawing the needles and pulling the suture ends through the vessel wall. The first actuator is released for retracting the suture arms. The suturing device is withdrawn from the body and the ends of the suture are tied for closing the incision. In one variation, the first actuator is releasably securable in the depressed position. In another variation, a first follower member is coupled to the suture arms by an actuating rod, wherein depression of the first actuator causes the first follower member to translate longitudinally within the handle portion for causing the arms to deploy. In another variation, a second follower member is coupled to the needles, wherein depression of the first actuator causes the second follower member to translate longitudinally within the handle portion for causing the needles to extend. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates one embodiment of a suturing apparatus and related assembly in an exemplifying use environment. 
         FIG. 2  illustrates an enlarged cross-sectional view of the suturing apparatus in an exemplifying use environment, such as a patient&#39;s thigh. 
         FIG. 3  is a perspective view of the suturing apparatus formed with an improved handle portion. 
         FIG. 3A  is a perspective view of an arm trigger, which forms a portion of the handle portion of the suturing apparatus of  FIG. 3 . 
         FIG. 3B  is a perspective view of a needle trigger, which forms a portion of the handle portion of the suturing apparatus of  FIG. 3 . 
         FIG. 4  is a side partial cross-sectional view of the handle portion wherein the arm trigger and needle trigger are in the non-depressed positions. 
         FIG. 5  is a side partial cross-sectional view of the handle portion wherein the arm trigger is fully depressed for locking the suture arms in the deployed condition. 
         FIG. 6  is a side partial cross-sectional view of the handle portion wherein both the arm trigger and the needle trigger are fully depressed for extending the needles to engage the suture ends held by the suture arms. 
         FIG. 6A  is a side view illustrating the relationship between the needle trigger and the second follower member in the handle portion. 
         FIG. 6B  is a perspective view of the second follower member. 
         FIG. 7  is a perspective view illustrating a preferred corner portion of the arm trigger wherein the corner portion is provided with a camming surface. 
         FIG. 8  is a side view illustrating a preferred embodiment of a release button for releasing the arm trigger and thereby retracting the suture arms. 
         FIG. 9  is a side view illustrating an alternative embodiment of a corner portion of the arm trigger wherein a section is cut away to facilitate the release of the arm trigger. 
         FIG. 10  is another perspective view illustrating a preferred corner portion of the arm trigger wherein the corner portion is provided with a camming surface. 
         FIG. 11A  is an enlarged perspective view of the distal end portion of the suturing apparatus of  FIG. 3 . 
         FIG. 11B  is perspective view of the distal end portion of  FIG. 11A  with a pair of suture arms partially deployed. 
         FIG. 11C  is a rear perspective view of the distal end portion of  FIG. 11A  with a pair of suture arms partially deployed. 
         FIG. 12A  is a perspective view of a suture end having a flattened distal portion with an eyelet. 
         FIG. 12B  is a perspective view of distal and proximal ends of a suture each having a flattened distal portion with an eyelet. 
         FIG. 13  is a cross-sectional view of the suturing apparatus of  FIG. 3  with the distal end portion inserted through an arterial wall. 
         FIG. 14  is a cross-sectional view of the suturing apparatus of  FIG. 3  with the distal end portion inserted through an arterial wall and a pair of suture arms partially deployed. 
         FIG. 15  is a cross-sectional view of the suturing apparatus of  FIG. 3  with a pair of suture arms fully deployed and a pair of needles engaging the suture arms. 
         FIG. 16  is a perspective view illustrating an alternative embodiment of a needle trigger wherein the camming surface is provided by a pair of opposing pins with a gap therebetween. 
         FIG. 17  illustrates an exemplifying path of the camming surface of  FIG. 16  during deployment and automatic retraction of the needles. 
         FIG. 18  is a side view illustrating an alternative configuration of the arm trigger and needle trigger wherein a compression spring is provided for biasing the triggers into the non-depressed positions. 
         FIG. 19  is a side view illustrating another alternative configuration of the arm trigger and needle trigger having a compression spring in a different location. 
         FIG. 20  is a perspective view illustrating an alternative embodiment of a follower member configured for engagement with the needle trigger of  FIG. 16 , wherein the follower member is provided with an inclined surface and a return slot for guiding the opposing pins back to the starting position. 
         FIG. 21  is a perspective view illustrating one preferred embodiment of an extrusion clamp for securing the elongate body to the handle portion. 
         FIG. 22  is a perspective view illustrating an alternative embodiment of a suturing apparatus having an improved handle portion wherein the needle trigger includes a looped portion. 
         FIG. 23  is a perspective view illustrating another embodiment of a suturing apparatus. 
         FIG. 24  is a side view of the handle of the suturing apparatus of  FIG. 23 , with a portion of a housing of the handle removed. 
         FIG. 25  is a perspective view of the first follower removed from the housing of  FIG. 24 . 
         FIG. 26  is a perspective view of the first follower member of  FIG. 25  from above. 
         FIG. 27  is a perspective view of the handle of the suturing apparatus of  FIG. 23 , with the first follower removed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the present invention described below relate particularly to closing incisions within biological tissue. While the description sets forth various embodiments and specific details, it will be appreciated that the description is illustrative only and should not to be construed in any way as limiting the invention. Furthermore, various applications of the invention, and modifications thereof, which may occur to those skilled in the art, are also encompassed by the general concepts described below. 
     With reference now to  FIG. 1 , one preferred assembly  4  for closing an incision is illustrated in an exemplifying use environment. The assembly  4  generally comprises a suturing apparatus  6  and a catheter sheath introducer (CSI)  8 . The suturing apparatus  6  may be used to seal a blood vessel following an interventional catheterization procedure, such as an angiogram, angioplasty or other procedure. With reference now to  FIG. 2 , an enlarged view of the treatment site is illustrated. In this view it can be seen that a physician makes an initial incision  10  in an upper thigh region  12  of a patient  2 . The physician then inserts a needle (not shown) into the incision  10  such that the needle pierces a femoral artery  14 , creating a vessel incision  16  therein. When blood bleeds back from the insertion, the physician knows the needle has entered the femoral artery  14 . The physician then inserts a guidewire (not shown) through the needle and into the artery  14 . The physician may take the needle out and insert a plastic needle (not shown) over the guidewire once the guidewire is in place. The guidewire may then be taken out. 
     With the plastic needle in place, the physician can insert the CSI  8 . The CSI  8  is typically a single-lumen catheter with a valve located on its proximal end. The valve is configured to prevent extraneous bleed back and/or to introduce medication into the patient&#39;s body. The vessel incision  16  provides access for medical instruments and probes inside the arterial vessel  14 . An instrument, such as a therapy catheter, may be advanced through the artery  14  via the CSI  8  to perform a procedure within the body. 
     After the medical procedure has been completed and the instrument (e.g., therapy catheter) has been removed, the physician inserts the suturing apparatus  6  through the CSI  8  such that a suture introducer head  20 , distally attached to a hollow elongate body  32 , enters the first incision  10 , passes through the tissue  18  of the patient&#39;s thigh  12 , and enters the femoral artery  14  through the vessel incision  16 . At this point, the suture arms  24 ,  24 ′ are deployed and the introducer head  20  of the suturing apparatus is pulled back such that the suture arms contact the inner wall  22  of the femoral artery  14 . As described in more detail below, needles are deployed from the introducer head which penetrate the wall  14  of the femoral artery  14  adjacent the incision  16 . The needles capture suture ends from the suture arms and the needles are then retracted to withdraw the suture ends back through the wall of the femoral artery. The arms are then retracted and the entire suturing apparatus is withdrawn such that the suture ends may be tied together to close the incision. 
     With reference now to  FIG. 3 , a preferred embodiment of the suturing apparatus  6  will be described in more detail. Additional details and methods of operation are described in Applicant&#39;s U.S. Pat. Nos. 6,245,079 and 6,562,052, each of which are hereby incorporated by reference in their entirety and are considered to be part of this specification. In addition, each of these patents is attached as an appendix. It will be appreciated that although the device  6  is preferably used for suturing vessel walls  22 , the device  6  can be used to suture other tissues such as, by way of example, a patent ductus arteriosus, a patent foramen ovale (PFO), a heart defect, a puncture wound, and the like. 
     In the embodiment illustrated in  FIG. 3 , the suturing apparatus  6  generally comprises an elongate body  32 , an introducer head  20  and a handle portion  100 . The handle portion  100  allows the physician to operate the suturing apparatus such that suture may be applied to an incision in a very quick and easy manner. The handle portion requires very little manipulation during use and may be operated with a single hand if necessary. The suturing apparatus may be used to close an incision located deep within the patient&#39;s tissue (e.g., in the femoral artery) without requiring the application of pressure over an extended period of time. As a result, the suturing apparatus may substantially reduce the recovery period following a medical procedure, thereby allowing the patient to return home more quickly and substantially reducing costs. The dimensions of the suturing apparatus  6  may vary according to the suture site and the biological tissue intended to be sutured. In one configuration, the suture introducer head  20  has a diameter of about 0.105 inches, and the hollow elongate body  32  has a diameter of about 0.098 inches. 
     The handle portion  100  comprises a main housing  102 , an arm trigger  104 , a needle trigger  106  and an arm release button  108 . The arm and needle triggers provide actuators for producing movement of internal components within the main housing, which in turn move at least one arm and needle for applying suture to a treatment site. As will be described in more detail below, the handle portion is constructed such that the arm trigger  104 , needle trigger  106  and arm release button  108  may be depressed by the physician in a particular order to extend and retract cooperating suture arms and needles along the introducer head  20  for applying suture to an incision. 
     The arm and needle triggers are preferably pivotally coupled to the main housing  102  about pin  110  such that the triggers rotate as they are depressed by the physician. As will be described in more detail below, the pivotal rotation facilitates the cam-like interaction of the triggers with the internal components of the main housing. An opening  112  is provided along the main housing  102  for allowing manual retraction of the needles in the event that the needles become stuck in the tissue during retraction. This provides a safety mechanism to ensure that the needles of the suturing apparatus cannot become stuck in the extended position. In one embodiment, a tool (not shown) is inserted through the opening  112  in the main housing  102  for applying force to assist in the refraction of the needles. 
     With reference to  FIG. 3A , the arm trigger  104  is shown in isolation. Loops  114 ,  116  are provided along the distal end of the arm trigger for receiving the pin  110  in the main housing. The bottom corner portion  120  along the proximal end portion of the arm trigger is shaped with a protrusion  120 A which provides a camming surface for engaging a first slidable follower member in the main housing. The protrusion also allows the arm trigger to be held in the depressed position for locking the arms in the deployed condition. The top surface  118  of the arm trigger is shaped for engagement with the physician&#39;s thumb or finger. 
     With reference to  FIG. 3B , the needle trigger  106  is shown in isolation. Loop  122  is provided along the proximal end of the needle trigger for receiving the pin  110  in the main housing. The loop is shaped to fit within the gap between the loops  114 ,  116  of the arm trigger  104  (see  FIG. 3A ). The bottom corner portion  130  along the distal end portion of the needle trigger provides a camming surface for engagement with a second slidable follower member in the main housing. The top surface  128  of the needle trigger is shaped for engagement with the physician&#39;s thumb or finger. 
     Preferred internal components of the handle portion  100  will now be described in more detail. The internal components cooperate with the arm and needle triggers  104 ,  106  (i.e., actuators) and arm release button  108  for effecting movement of the arms and needles during the application of suture. More specifically, the arm and needle triggers actuate the arms and needles by effecting movement of the internal components contained with the main housing. As described above, the arm and needle triggers each preferably have corner portions  120 ,  130  shaped with camming surfaces which interact with first and second slidable follower members in the main housing. The follower members are caused to translate longitudinally when the arm or needle triggers are depressed by the physician. 
     With reference now to  FIG. 4 , a cross-sectional side view of the handle portion  100  is shown for purposes of illustration. It can be seen that a first follower member  140  is slidably disposed within the interior of the main housing  102 . The first follower member  140  is connected to a proximal end of an actuating rod, preferably through a drive wire tab  156  described below, which extends distally through the main housing and elongate body for connection to each of the arms. When the first follower member  140  is in the distal position, as shown in  FIG. 4 , the arms are fully contained within the introducer head. However, when the first follower member  140  is moved proximally by the arm trigger  104  (indicated by the arrow in  FIG. 5 ), each of the arms deploys outward through apertures on the sides of the introducer head. (The operation of the arms and needles will be described in more detail below.) Accordingly, longitudinal movement of the first follower member  140  relative to the main housing controls the position of the arms. An arm spring  144  provides a biasing force to maintain the first follower member  140  in the distal position in the absence of any external input. Although one type of arm spring is shown for purposes of illustration, any known biasing mechanisms may be used for maintaining the first follower member  140  into the distal position. 
     It can be seen that the first follower member  140  is formed with an inclined “cammed” surface  142  along a distal face. As shown in  FIG. 4 , the inclined cammed surface is configured for engagement with the camming surface along the corner portion  120  of the arm trigger  104 . When the arm trigger  104  is depressed, the corner portion  120  of the arm trigger  104  pushes along the inclined surface  142  of the first follower member  140 . The downward force acting on the inclined surface results in longitudinal translation of the first follower member. The longitudinal force causes the first follower member to slide in a proximal direction (i.e., backward) within the main housing. As the first follower member slides backward, the actuating rod is pulled in a proximal direction, thereby causing the arms to deploy outward through the ports. 
     The arm trigger  104  is preferably releasably securable in the fully depressed condition for locking the arms in the deployed condition. As a result, it is not necessary for the physician to apply a constant a force on the arm trigger  104  to maintain the suture arms in the deployed condition. As described above, the corner portion  120  of the arm trigger is preferably formed with a protrusion  120 A.  FIG. 7  provides an enlarged view of the corner portion  120  including the protrusion  120 A. The protrusion is shaped to be captured and held beneath the first follower member  140  when the arm trigger  104  is fully depressed. As discussed above, the arm spring  144  urges the first follower member forward (in the distal direction) such that the first follower member abuts the arm trigger and securely holds the protrusion. Accordingly, the cooperation of the protrusion and the first follower member creates a detent mechanism such that the arm trigger is selectively maintained in the depressed position.  FIG. 10  provides another perspective view of the corner portion of the arm trigger. 
     With reference again to  FIG. 4 , the arm release button  108  is configured for releasing the protrusion when it is desired to retract the deployable arms. As illustrated, the arm release button  108  is preferably provided along a proximal end of the main housing  102  and is configured for engagement with the arm trigger  104 . An arm release spring  144  may be provided for maintaining the arm release button  108  in the non-depressed condition in the absence of an external input. Accordingly, the arm release button can only act on the arm trigger when a sufficient force is applied to overcome the biasing force of the arm biasing spring  144 . With reference now to  FIG. 8 , the arm release button  108  is shown in isolation. The arm release button is provided with an elongate member  108 A that is configured to contact the corner portion of the arm trigger when the arm trigger is being held in the fully depressed condition. More particularly, the elongate member  108 A is configured to urge the arm trigger in the distal direction such that the protrusion is released from the first follower member.  FIG. 9  is a cross-sectional view illustrating an alternative arm trigger wherein a section of the corner portion has been cut away to facilitate the release of the arm trigger upon actuation of the arm release button. It will be appreciated that alternative methods may be used to release the arm trigger. For example, the arm trigger may be provided with a lip on its upper surface and an actuator may be used to engage the lip to pull the arm trigger back to its initial position. 
     A second follower member  150  is slidably disposed within the interior of the main housing at a location distal to the first follower member  140 . The second follower member  150  is connected to the proximal ends of the elongate needles  70 ,  70 ′. Thus, longitudinal movement of the second follower member  150  relative to the main housing  102  effects the position of the needles. The second follower member  150  has a proximal position (as shown in  FIGS. 4 and 5 ) wherein the needles are in the retracted (non-deployed condition). A needle biasing spring  154  engages the second follower member for maintaining the second follower member in the proximal position in the absence of any external input. Although one particular embodiment of a needle biasing spring  154  is shown for purposes of illustration, a wide variety of different biasing mechanisms may be used for biasing the second follower member into the proximal position. 
     The second follower member  150  is provided with an inclined “cammed” surface  152  along the proximal face such that the second follower member cooperates with a camming surface along the corner portion  130  of the needle trigger  106  in a manner substantially similar to that of the first follower member. More particularly, as shown in  FIG. 5 , the inclined surface is shaped for slidable engagement with a camming surface of the needle trigger  106 . 
     As the needle trigger  106  is depressed, the camming surface along the corner portion  130  of the needle trigger pushes against the inclined surface  152  of the second follower member  150 , as illustrated in the cross-sectional view of  FIG. 6A . The force from the needle trigger creates a resulting longitudinal force on the second follower member that causes the second follower member to slide distally relative to the main housing. As the second follower member translates distally within the housing (as denoted by the arrow in FIG.  6 A), the needles  70 ,  70 ′ are pushed in a distal direction, thereby causing the distal end portions of the needles to extend outward from the introducer head for engagement with the suture arms. The extension of the needles from the introducer head will be described in more detail below. In preferred embodiments, the second follower member  150  is contained within a body portion that is integral with the first follower member. The body portion provides a slotted track such that the second follower member may be guided proximally and distally during use. Thus, the first and second follower members are preferably slidably coupled to each other. It should also be noted that the second follower member may be formed with a longitudinal lumen for slidably receiving the actuating rod  58 . Accordingly, the actuating rod  58  may be slid longitudinally by movement of the first follower member without interfering with the second follower member.  FIG. 6B  provides a perspective view of the second follower member  150  having an inclined surface  152 . It can be seen that the lower portion of the second follower member is thinner in construction. The thinner section is configured to fit within a groove in the body portion for guiding the movement of the second follower member, as described above. The second follower member is also formed with a slot  160  for receiving a tool through the window  112  in the main housing  102  ( FIG. 3 ). The tool may be inserted through the window and into the slot. The tool may then be used to slide the second follower member in the event that it sticks, thereby providing a safety mechanism as described above. 
     The cammed surface of the first and second follower members is shaped to produce a desired motion in response to actuation of the arm and needle triggers, respectively. In one preferred embodiment, at least a portion the cammed surface of the second follower member is inclined at about 35° or more relative to the longitudinal axis. The angle of inclination is denoted by the symbol α (alpha) in  FIG. 6A . In another embodiment, at least a portion of the cammed surface is inclined at about 40° or more relative to the axis. In another variation, at least a portion of the cammed surface is inclined at about 41° relative to the axis. In another variation, at least a portion of the cammed surface is inclined at between about 35-45° relative to the axis. In another variation, at least a portion of the cammed surface is inclined at between about 39-43° relative to the axis. In another variation, at least a portion of the cammed surface is inclined at between about 40-42° relative to the axis. In still another variation, the camming surface is curved. The same preferred ranges also apply to the cammed surface of the first follower member. It will be appreciated that the ratio of trigger movement to needle movement is proportional to the angle of the inclined surface. It has been found that the above angles provide excellent performance while minimizing the diameter of the handle portion. For example, a lower angle would make the follower members more difficult to move due to frictional forces. On the other hand, a higher angle would necessitate a larger follower member in order to produce the same amount of longitudinal translation, thereby necessitating a larger (e.g., larger diameter) handle portion. Furthermore, it has been found that an inclined surface formed with a substantially constant angle provides a substantially directly proportional relationship between trigger movement and needle movement. As a result, the physician is able to advance and retract the needles with great precision and predictability by controlling the movement of the needle trigger. 
     With reference again to  FIGS. 4 through 6 , the main housing  102  is preferably constructed of a translucent or transparent material, such as plastic, such that the movement of the components within the main housing is visible to the physician. The transparency advantageously provides visual feedback to the physician regarding operation of the suturing apparatus. If desired, markings or other indicia may be provided such that the position of the needles may be easily perceived during use. Alternatively, a window may be provided for observing the movement of the internal components or a portion of one or more internal components may extend through the main housing to an exterior surface for purposes of visibility. 
     With reference to  FIGS. 11A through 11C , the distal end portion of the suturing apparatus will now be described in more detail. The illustrated distal end portion provides one preferred embodiment that may be operated using the improved handle portion described above. As shown, the distal end portion comprises the suture introducer head  20 , a pair of suture arms  24 ,  24 ′, a pair of suture clasps  56 ,  56 ′, a pair of suture arm apertures  50 ,  50 ′, a pair of curved or slanted needle guides  48 ,  48 ′, a pair of needle apertures  30 ,  30 ′, a distal end  54 , a hole  46 , a suture  52  and an actuating rod  58 . The distal end portion further comprises a pair of needles  70 ,  70 ′ (see  FIGS. 13 through 15 ). When the suture arms  24 ,  24 ′ are retracted into the suture arm apertures  50 ,  50 ′ and the needles  70 ,  70 ′ are refracted into the needle apertures  30 ,  30 ′, the arms  24 ,  24 ′ and the needles  70 ,  70 ′ are recessed within the suture introducer head  20 , as shown in  FIG. 11A . This prevents the arms  24 ,  24 ′ and the needles  70 ,  70 ′ from causing tissue damage while the distal end portion passes through a biological structure. 
       FIGS. 11B and 11C  illustrate the distal end portion of the device  6  ( FIG. 3 ) with the suture arms  24 ,  24 ′ partially deployed outwardly from their recessed positions. Such deployment is achieved by partially depressing the arm trigger  104 , as described above with reference to  FIGS. 4 through 6 . Depressing the arm trigger  104  translates the first follower member  140  ( FIG. 4 ) and actuating rod  58  proximally, which brings the suture arms  24 ,  24 ′ into contact with a pair of proximal inside edges  78 ,  78 ′ of the suture arm apertures  50 ,  50 ′. As the arm trigger is depressed further, the proximal inside edges  78 ,  78 ′ force the suture arms  24 ,  24 ′ into a deployed state. In one embodiment, the suture arms  24 ,  24 ′ continue to deploy radially until the arms  24 ,  24 ′ are substantially parallel with each other and substantially perpendicular to the longitudinal axis of the suture introducer head  20 , as shown in  FIG. 15 . In other embodiments, the suture arms  24 ,  24 ′ may be “fully” deployed when they reach an acute or obtuse angle relative to each other. 
     As shown most clearly in  FIG. 11B , each of the suture arms  24 ,  24 ′ comprises a suture clasp  56 ,  56 ′ which holds an end of the suture  52 . Each of the suture arms  24 ,  24 ′ are pre-loaded with the ends of the suture  52  before operation. The ends of the suture  52  then pass from the suture clasps  56 ,  56 ′ to the hole  46  whereby the ends of the suture  52  enter the suture introducer head  20  and are passed proximally through the hollow elongate body  32 . In the embodiment illustrated in  FIG. 11B , each end of the suture  52  has a capture portion comprising a loop which is tied onto the ends of the suture claps  56 ,  56 ′. It is contemplated, however, that the capture portions are not restricted solely to tied loops, rather other types of capture portions may be utilized such as, by way of example, spheres or ferrules. 
       FIG. 12A  illustrates another embodiment of a capture portion wherein the end of the suture  52  comprises a flattened distal region  93  having a hole or eyelet  95 . In the embodiment illustrated in  FIG. 12A , the suture  52  comprises a strand  91  of deformable material that is preferably monofilament, such as Deklene (from Genzyme), Prolene (from Johnson &amp; Johnson), or Nylon (from Johnson &amp; Johnson). In one embodiment, the strand  91  is advantageously approximately 0.010″ thick and has a length that makes it suitable for use in suture procedures. 
     In the formation of the flattened distal portion  93 , the distal end of the strand  91  is heated until the distal end melts or is otherwise plastically or thermally deformed to form a locally deformed region (such as a globule) that is broader than the rest of the strand  91  in at least one dimension (i.e., at least one dimension of the strand  91  has been increased). Once the deformed region is formed, the strand  91  may be allowed to cool, and the deformed region may then be flattened by use of a die. The die preferably has a relief or recessed portion for accepting the strand  91  and the deformed region. A block, which preferably also has a recessed portion that mates with the recessed portion, may then be placed over the deformed region. The deformed region is then squeezed between the die and the block, resulting in the formation of the flattened distal portion  93  illustrated in  FIG. 12A . The flattened distal portion  93  preferably has a thickness that matches the rest of the strand  91 . The edges of the flattened distal portion  93  may then be trimmed to form a smooth disc portion to reduce the risk of such edges snagging on vessel walls during suturing procedures. 
     As illustrated in  FIG. 12A , the eyelet  95  is formed within the flattened distal portion  93 . A punch (not shown) such as a hypotube may be used to poke through the flattened distal portion  93 , thereby leaving the eyelet  95  within the flattened distal portion  93 . The eyelet  95  is formed such that a surgical hook or needle may pass through the eyelet  95  in a suturing procedure. The flattened distal portion  93  acts as a connector to the hook or needle, allowing the strand  91  to be picked up by the hook or needle. The method of forming the eyelet  95  described herein, including the forming of the flattened distal portion  93 , advantageously results in no significant reduction in the mechanical strength of the strand  91 , with the material throughout the strand  91  (including the material in the flattened distal portion  93 ) having substantially uniform mechanical strength. Methods for forming the flattened distal region  93  are discussed in greater detail in Applicant&#39;s above-mentioned U.S. Pat. No. 6,562,052, entitled SUTURING DEVICE AND METHOD. 
     Advantageously, the suture embodiment shown in  FIG. 12A  has no knots or ties formed therein which might increase the profile of the suture strand  91  or make it easier for the suture  52  to snag during use. This process may advantageously be repeated at the proximal end of the strand  91 , resulting in eyelets  95 ,  95 ′ at both ends of the strand  91 , as illustrated in  FIG. 12B . The flattened distal portion  93  at one or more of the ends of the strand  91  may be bent (not shown) at an angle with respect to the rest of the strand  91  to facilitate the guiding of a surgical needle through the eyelet  95 . 
       FIG. 11C  illustrates one preferred configuration of the hollow elongate body  32  which comprises five lumens. Two of the lumens  60 ,  60 ′ are used to house the needles  70 ,  70 ′. Once the suture arms  24 ,  24 ′ have been deployed, as discussed with reference to  FIGS. 11B and 11C  (and in greater detail below), the needle trigger  106  ( FIG. 3 ) can be depressed to advance the needles  70 ,  70 ′ from a recessed position within the suture introducer head  20  to a distally extended position (see  FIG. 15 ). In one embodiment, the needles  70 ,  70 ′ move distally at substantially the same time. In another embodiment, the needles  70 ,  70 ′ may be actuated separately such that one of the needles  70 ,  70 ′ advances before the other. 
     When the two needles  70 ,  70 ′ move distally, the needle guides  48 ,  48 ′ direct the needles  70 ,  70 ′ out of the needle apertures  30 ,  30 ′ at an angle relative to the longitudinal axis of the suture introducer head  20 , as illustrated in  FIG. 15 . The needles  70 ,  70 ′ are flexible and preferably made of a material with shape memory, such as SUPERFLEX NITINOL™. Alternatively, the needles  70 ,  70 ′ may be comprised of spring steel, surgical stainless steel or any variation thereof. Each of the needles  70 ,  70 ′ preferably has a diameter of about 0.019 inches, but needles with other diameters may be used in accordance with the particular medical procedure contemplated. 
     When the needles  70 ,  70 ′ advance distally, as discussed above, the needle guides  48 ,  48 ′ cause the needles  70 ,  70 ′ to bend radially outward. As shown most clearly in  FIG. 15 , a further outward, radial bend preferably is imparted to the needles  70 ,  70 ′ when they come into contact with a pair of angled surfaces  57 ,  57 ′ of the suture arms  24 ,  24 ′. When the needles  70 ,  70 ′ are refracted into the needle lumens  60 ,  60 ′, the needles  70 ,  70 ′ resume a straight configuration as a result of their resiliency. Although the embodiment of  FIGS. 11A through 15  preferably comprises flexible needles  70 ,  70 ′, which bend during deployment, it is contemplated that other embodiments may advantageously comprise rigid needles which may be permanently straight or curved. 
     Referring again to  FIG. 11C , the hollow elongate body  32  contains a central lumen  64  which is used to house the actuating rod  58 . Another lumen  62  is used to house the length of the suture  52  to prevent the suture  52  from becoming tangled. Alternatively, the suture  52  may be passed through the central lumen  64  along with the actuating rod  58 . 
     A fifth lumen  62 ′ is preferably used for “bleed back,” which enables the physician to determine whether the distal end  54  of the suture introducer head  20  is positioned within the artery  14 . Bleed back is accomplished through the hole  46  at the distal end  54  of the suture introducer head  20 , the suture arm apertures  50 ,  50 ′ and any other openings in the suture introducer head  20 . The direction of blood flow for bleed back is indicated by three dashed arrows in  FIG. 13 . If the distal end  54  of the suture introducer head  20  is positioned within the artery  14 , blood pressure due to blood entering into the hole  46  will be much greater than if the distal end  54  is not within the artery  14 . In one embodiment, the lumen  62 ′ extends to a port (not shown) at a proximal portion of the device  6 , whereby the physician can determine the blood pressure within the bleed back lumen  62 ′ by monitoring blood flow from the port. For example, the lumen  62 ′ may be attached to a balloon which inflates when the distal end  54  of the suture introducer head  20  passes into the blood vessel  14 . In another embodiment, a pressure sensor may be coupled with the lumen  62 ′ to provide the physician with a numeric blood pressure reading. Alternatively, the lumen  62 ′ may be used to inject medication or for diagnostic purposes. 
     In a preferred embodiment, two thin stripes  66  (only one shown in  FIG. 11C ) marked on the exterior of the hollow elongate body  32  extend along the entire length of the hollow elongate body  32 . The stripes  66  provide a visual indication of the circumferential location of the needles  70 ,  70 ′ relative to the hollow elongate body  32 . The stripes  66  facilitate aligning the needles  70 ,  70 ′ with the axis of the blood vessel  14 , so that needle incisions  80 ,  80 ′ (see  FIG. 15 ) formed in the vessel wall  22  by the needles  70 ,  70 ′ will be aligned along a dimension transverse to the flow of blood within the artery  14 . This enables the physician to place the suture  52  within the vessel wall  22  such that the suture  52  closes the incision  16  transversely to the blood flow. This is the most efficient direction to close the incision  16 . Proper insertion of the needles  70 ,  70 ′ reduces the risk of damage to the vessel wall  22 . Alternatively, the hollow elongate body  32  may have only one stripe  66  which denotes the circumferential location of one of the two needles  70 ,  70 ′. Because the needles  70 ,  70 ′ deploy from opposite sides of the suture introducer head  20 , knowledge of the location of one needle provides the physician with knowledge of the location of the other needle. 
     As illustrated in  FIG. 11C , the exterior surface of the hollow elongate body  32  includes a marker  68  which denotes a proximal position to which the CSI  8  should be partially withdrawn (after the distal portion  26  of the suturing apparatus  6  has been inserted into the blood vessel  14 ) to expose the needle apertures  30 ,  30 ′. The partial withdrawal of the CSI  8  is discussed in detail in Applicant&#39;s above-mentioned U.S. Pat. No. 6,562,052, entitled SUTURING DEVICE AND METHOD. The marker  68  is shown as a visual marker, but may additionally or alternatively be in the form of a ridge, groove, or other physical structure which interacts with a corresponding structure of the CSI  8  to allow the physician to position the CSI  8  using a sense of feel. For example, the CSI  8  and the hollow elongate body  32  could be configured to releasably engage or interlock with one another when the CSI  8  reaches a predetermined position along the elongate body  32 . It is contemplated that a specially formed CSI  8  comprises such an interlocking structure, and is included within the scope of the invention. It is further contemplated that one or more additional markers (not shown) may advantageously be provided along the length of the hollow elongate body  32 , distal to the marker  68 , to indicate other positions of the CSI  8  relative to the elongate body  32 , such as the position at which the suture arms  24 ,  24 ′ are exposed outside the CSI  8 . 
     The use and operation of the suturing apparatus will now be described with reference to  FIG. 3 through 15 . From the following description, it will be understood that the handle portion  100  provides an improved mechanism for quickly and easily actuating the components of the suturing apparatus to apply suture to an incision, such as to close a vessel wall after a surgical procedure. 
     Before the procedure, the suture arms  24 ,  24 ′ are pre-loaded with the ends of a suture, such as, for example, a polypropylene suture. Specifically, each end of a suture has a capture portion comprised of a loop, a sphere or a ferrule. In one embodiment, the loop, sphere or ferrule may be formed (e.g., by heat molding) with the same suture material as the length of suture. In another embodiment, the loop, sphere or ferrule may be a separate piece attached (e.g., molded, glued, etc.) onto each end of the length of suture. The loop, sphere or ferrule is loaded in respective suture end supports of the arms  24 ,  24 ′. The remaining length of the suture preferably extends through the hollow elongate body. With the CSI  8  extending into the patient&#39;s artery  14 , the physician then inserts the suture introducer head  20  through the CSI  8  and into the artery  14 . The CSI  8  is then partially withdrawn along the hollow elongate body  32  to remove the CSI  8  from the artery  14  and to expose the needle apertures  30 ,  30 ′, as shown in  FIG. 13 . The markers  68  ( FIG. 11C ) on the exterior surface of the hollow elongate body  32  indicate how far the physician should withdraw the CSI  8  to expose the needle apertures  30 ,  30 ′. 
     The distal end  54  of the suture introducer head  20  has a smooth, rounded surface which prevents injury to the opposite vessel wall  22  when the suture introducer head  20  is inserted into the artery  14 . In addition, blood flow within the artery  14  is uninterrupted because the suture introducer head  20  does not occlude the artery  14 . The physician may use bleed back through the hole  46  and the lumen  62 ′ ( FIG. 11C ) to determine when the suture introducer head  20  has entered into the artery  14 . 
     During insertion into the artery, the arm trigger  104  and needle trigger  106  are each in the non-depressed positions, as depicted in  FIG. 4 . As a result, the first follower is located in the distal position such that the suture arms are in the retracted condition. Also, the second follower is in the proximal position such that the needles are in the retracted condition. 
     While the suture introducer head  20  is inserted into the artery  14 , as shown in  FIG. 13 , the actuating rod  58  holds the suture arms  24 ,  24 ′ in a recessed state within the suture introducer head  20 . The actuating rod  58  applies a downward force while a pair of deflection surfaces  67 ,  67 ′ of the suture introducer head  20  apply an inward force on each of the suture arms  24 ,  24 ′, respectively. The combination of these two forces retains the suture arms  24 ,  24 ′ within the suture arm apertures  50 ,  50 ′ of the suture introducer head  20 . Each of the suture clasps  56 ,  56 ′ comprises an angled slot which holds a looped end of the suture  52  as illustrated in  FIGS. 11A through 11C . The looped ends of the suture  52  are held securely by the suture clasps  56 ,  56 ′, but are positioned for easy removal by a pair of suture catches  72 ,  72 ′ at the tips of the needles  70 ,  70 ′. 
     Once the distal portion  26  of the device  6  is properly positioned within the artery  14 , the physician depresses the arm trigger  104  ( FIG. 3 ) to deploy the suture arms  24 ,  24 ′ as shown in  FIG. 14 . Downward movement of the arm trigger acts on the first follower member  140  in the main housing  102 , thereby causing the first follower member to translate proximally, which pulls the actuating rod proximally. The corner portion  120  of the arm trigger  104  provides a camming surface which engages an inclined cammed surface on the first follower member  140 . During this action, the force applied on the arm trigger must be sufficient to overcome the biasing force of the arm spring  144 . Movement of the first follower member  140  translates the actuating rod  58  proximally, which relieves the downward force applied by the actuating rod  58  and thus also relieves the inward forces applied to the suture arms  24 ,  24 ′ by the deflection surfaces  67 ,  67 ′. This allows the suture arms  24 ,  24 ′ to assume a partially deployed state as illustrated in  FIG. 14 . As the physician continues depressing the arm trigger  104 , the actuating rod  58  continues translating proximally, bringing the suture arms  24 ,  24 ′ into contact with the proximal inside edges  78 ,  78 ′. The proximal inside edges  78 ,  78 ′ apply a downward force on each of the suture arms  24 ,  24 ′, respectively, thereby forcing the suture arms  24 ,  24 ′ into a fully deployed state as illustrated in  FIG. 15 . 
     With reference now to  FIG. 5 , as the arm trigger  104  becomes fully depressed, the protrusion  120 A along the corner portion  120  of the arm trigger  104  advances beneath the first follower body  140 . In this position, the arm trigger  104  is maintained in the fully depressed position by the force of the arm spring  144 , which pushes the first follower body against the arm trigger. Accordingly, the cooperation between the arm trigger and the first follower body advantageously provides a releasable detent mechanism for holding the arm trigger in the depressed position. When the arm trigger is held in the fully depressed condition, the suture arms  24 ,  24 ′ are locked in the fully deployed condition. 
     In the locked state, the suture arms  24 ,  24 ′ preferably have reached a fully extended position and are longitudinally aligned with each other, as illustrated in  FIG. 15 . With the suture arms  24 ,  24 ′ in this fully extended position, the physician may gently slide the suturing apparatus  6  proximally so that the suture arms  24 ,  24 ′ contact the interior surface of the vessel wall  22 . 
     At this juncture, the physician depresses the needle trigger  106  on the handle portion  100  to distally advance the needles  70 ,  70 ′ and capture the ends of the suture  52  from the suture clasps  56 ,  56 ′.  FIG. 5  illustrates the needle trigger in the non-depressed position.  FIG. 6  illustrates the needle trigger in the fully depressed position. During downward depression of the needle trigger, the camming surface along the corner portion  130  of the needle trigger  106  engages and slides along the cammed surface of the second follower member  150 , thereby causing the second follower member to slide longitudinally within the main housing  102  in a distal direction. During this action, the force applied on the needle trigger  106  must be sufficient to overcome the biasing force of the needle biasing spring  154 . As the needle trigger is depressed further, the second follower member continues to slide distally, thereby advancing the needles distally through the main housing and through the hollow elongate body. As the first and second needles advance distally, the distal ends of the needles extend outward for engagement with the arms. 
     The paths taken by the needles  70 ,  70 ′ are illustrated in  FIG. 15 . The needles  70 ,  70 ′ slide along the needle lumens  60 ,  60 ′ and out of the suture device  6  through the needle apertures  30 ,  30 ′, respectively. When the needles  70 ,  70 ′ come in contact with the needle insertion guides  48 ,  48 ′, the needles  70 ,  70 ′ begin to bend radially outward. As the needles  70 ,  70 ′ exit, they are guided at a radially outward, acute angle away from the actuating rod  58  by the needle insertion guides  48 ,  48 ′. The angle of the needle deflection is preferably about 13.2 degrees. Deflection angles between about 10 degrees and about 15 degrees and between about 5 degrees and about 20 degrees are also contemplated. 
     During advancement, the needles  70 ,  70 ′ penetrate the vessel wall  22  at an angle, thereby creating the needle incisions  80 ,  80 ′ on opposite sides of the incision  16 . As mentioned above, the needles  70 ,  70 ′ also preferably bend slightly (radially outward) when they come in contact with the suture arms  24 ,  24 ′. The angled surfaces  57 ,  57 ′ of the suture clasps  56 ,  56 ′ and the suture catches  72 ,  72 ′ exert a force on each of the looped ends of the suture  52  such that the looped ends remain tied to the suture clasps  56 ,  56 ′ while the needles  70 ,  70 ′ pass therein. 
     The physician depresses the needle trigger  106  until the suture catches  72 ,  72 ′ of the needles  70 ,  70 ′ engage the suture clasps  56 ,  56 ′ and capture the looped ends of the suture  52 . As shown in  FIG. 15 , the suture arms  24 ,  24 ′ hold the looped ends of the suture  52  away from the suture introducer head  20  so that the needles  70 ,  70 ′ pierce the vessel wall  22  and capture the looped ends of the suture  52  outside the perimeter of the suture introducer head  20 . Mechanical limits prevent additional movement of the needle trigger  106  once the needles  70 ,  70 ′ have optimally engaged the suture clasps  56 ,  56 ′. Such resistance signals to the physician that the needles  70 ,  70 ′ have reached an optimal, predetermined location within the suture clasps  56 ,  56 ′. 
     After the physician advances the needles  70 ,  70 ′ to the optimal, predetermined location within the suture clasps  56 ,  56 ′, the physician releases pressure on the needle trigger  106 , thereby allowing the needle biasing spring  154  within the handle portion  100  (see  FIGS. 4-6 ) to retract the needles  70 ,  70 ′ proximally. This motion causes the needles  70 ,  70 ′ to withdraw into the needle lumens  60 ,  60 ′ with the looped ends of the suture  52  attached to the suture catches  72 ,  72 ′. The suture catches  72 ,  72 ′ capture the looped ends of the suture  52  held by the suture clasps  56 ,  56 ′ and pull the looped ends up through the needle incisions  80 ,  80 ′ as the needles  70 ,  70 ′ retract proximally. As the needles  70 ,  70 ′ pull proximally on the looped ends of the suture  52 , tension in the suture  52  causes additional segments of the suture  52  to feed through the hole  46  at the distal end  54  of the suture introducer head  20 , into the artery  14  and through the needle incisions  80 ,  80 ′. In this embodiment, the physician may regulate the rate of needle movement by controlling the rate of movement of the needle trigger. From the above, it can be seen that the position of the needles is substantially directly proportional with the position of the needle trigger. Accordingly, by sensing the position of the needle trigger, the physician is provided with a reliable indication of needle position at any given time. 
     In the above-described embodiment, the physician advantageously controls the position of the needles  70 ,  70 ′ by depressing and releasing the needle trigger  104 . The advancement of the needle is achieved by depressing the needle trigger in a controlled manner, while retraction is achieved by allowing the needle spring to retract the needle while the physician regulates the rate of retraction with the needle trigger. Once the needles  70 ,  70 ′ have been retracted into the needle lumens  60 ,  60 ′, the physician depresses the arm release button  108  ( FIG. 3 ) to release the arm trigger  104 . The arm release button urges the corner portion  120  of the arm trigger  104  in a distal direction such that the protrusion  120 A is released from the first follower member  140 , thereby allowing the arm trigger  104  to spring back upward. 
     Once the arm trigger  104  is released, the arm biasing spring  144  pushes the first follower member  140  distally, thereby moving the actuating rod  58  distally. This relieves the forces applied to the suture arms  24 ,  24 ′ by the proximal inside edges  78 ,  78 ′, allowing the suture arms  24 ,  24 ′ to assume a relaxed state as illustrated in  FIG. 14 . Upon further distal movement of the first follower member  140 , the suture arms  24 ,  24 ′ move distally until contacting the deflection surfaces  67 ,  67 ′. Together with the deflection surfaces  67 ,  67 ′, the downward force of the actuating rod  58  causes the suture arms  24 ,  24 ′ to retract into the recessed state within the suture introducer head  20 , as shown in  FIG. 13 . In the recessed state, the suture arms  24 ,  24 ′ are substantially parallel with the hollow elongate body  32 , and the exterior surfaces of the suture arms  24 ,  24 ′ are substantially flush with the exterior surface of the introducer head  20 . This reduces the likelihood that the suture arms  24 ,  24 ′ will snag or catch on the vessel wall  22  or the flesh  18  during withdrawal. With the suture arms  24 ,  24 ′ and the needles  70 ,  70 ′ returned to the recessed state, the device  6  is ready for removal from the artery  14 . 
     With reference again to  FIG. 1 , the physician then withdraws the device  6  out of the artery  14  and out of the tissue  18  of the patient&#39;s thigh  12 . After the device  6  is fully withdrawn (and with the CSI  8  still in the tissue  18 ), the physician gently pulls the ends of the suture  52  to close the vessel incision  16 . In the embodiment wherein the suture  52  passes through the needle incisions  80 ,  80 ′, when the ends of the suture  52  are pulled, tension in the suture  52  closes the vessel incision  16 . The physician then ties at least one knot, preferably a fisherman&#39;s knot or an improved clinch knot, with the ends of the suture  52  and slides or pushes the knot(s) down through the CSI  8  to the vessel incision  16 . The physician may tie and push the knot(s) by using any suitable suture knot tying and/or cinching apparatus including an apparatus disclosed in Applicant&#39;s application entitled METHOD AND APPARATUS FOR TYING SUTURE KNOTS, Ser. No. 09/923,108, filed Aug. 6, 2001, the entirety of which is hereby incorporated by reference. Alternatively, the physician may tie at least one knot by hand and then cinch the knot by using a knot cinching device, such as an apparatus taught by Applicant&#39;s application titled KNOT PUSHER, Ser. No. 09/571,759, filed May 15, 2000, which is incorporated herein by reference in its entirety. Still, the physician may choose to fasten a small, circular or flat stainless steel clip (not shown) to the ends of the suture  52  and slide the clip down through the CSI  8  to the vessel incision  16  to close the incision  16 . Other embodiments for tying and placing knots are described in Applicant&#39;s application entitled HANDLE FOR SUTURING APPARATUS, Ser. No. 60/613,636, filed Sep. 27, 2004, and METHOD AND APPARATUS FOR HOLDING SUTURE ENDS TO FACILITATE TYING OF KNOTS, Ser. No. 60/683,701, filed May 23, 2005, the entirety of both of which are incorporated by reference. The physician then cuts the unused ends (extra length) of the suture  52  and removes the cut portions. The physician then removes the CSI  8  from the patient&#39;s thigh  12 . 
     In one alternative embodiment, the suturing apparatus may be provided with a lumen for slidably receiving a guidewire. In one example, the guidewire lumen may be combined with the bleed back lumen. The guidewire lumen is provided for assisting the physician during insertion of the suturing apparatus into the patient and advancing the device toward the treatment site. 
     With reference now to  FIGS. 16 through 20 , one alternative needle actuation mechanism is provided. With particular reference to  FIG. 16 , a needle trigger  206  is formed with first and second pins  208 ,  210  and a gap therebetween. The needle trigger is configured for cooperation with the follower member  250  shown in  FIG. 20 . In this embodiment, the pins  208 ,  210  of the needle trigger  206  initially ride along the inclined surface  252  of the follower member  250 , thereby causing the follower member to move in a distal direction for extending the needles. However, as the needle trigger reaches a finish (i.e., fully depressed) position, the pins extend beyond the bottom edge of the inclined surface, thereby relieving the force on the follower member and allowing the follower member to snap back in a proximal direction. This occurs while maintaining the needle trigger in the fully depressed condition. Accordingly, the needles are first fully extended and then automatically snap back when the needle trigger reaches a first finished position (i.e., is fully depressed). The needles snap back due to the spring biasing of the follower member. When the needle trigger is released, the pins ride back up via slots  256  to the start position.  FIG. 17  illustrates an exemplifying path of the pins during this cycle.  FIGS. 18  and  19  illustrate spring mechanism  258  or  260  for biasing the arm and needle triggers back into the start position. 
     If desired, the relationship between the needle trigger and the follower member may be configured such that the needles retract from the first finished position at a first rate and then retract from a second finished position at a faster rate. This may be achieved by providing a cut away portion (such as in  FIG. 9 ) on the follower member. This retraction of the needles at a slow rate followed by a fast rate advantageously provides a “pre-tensioning” of the suture such that the needles initially tug slowly on the suture ends and then more quickly. The initial slow tugging allows the suture ends to become better aligned before withdrawal through the tissue. 
     With reference now to  FIG. 21 , one preferred embodiment of an extrusion clamp  180  is illustrated. The clamp provides a transition between the handle portion  100  and the elongate body. The clamp includes a central lumen  182  for receiving the actuator rod and needles. The clamp also includes a depression for seating the needle biasing spring  154 . 
     In another alternative embodiment, as shown in  FIG. 22 , the needle trigger  106 A may be provided with a looped portion configured to receive the physician&#39;s thumb or finger. The looped portion advantageously allows the physician to pull upward on the needle trigger without relying on the biasing spring force to raise the needle trigger. This embodiment provides the physician with greater control over the movement of the needles. 
     In another alternative embodiment, the suturing apparatus may be provided without an arm release button. Rather, the arm trigger could be constructed such that the initial depression moves the arm trigger into the locked position. Pressing the arm trigger again causes the arm trigger to become released and pop back up. Any release mechanism of the types known in the art may be used for this purpose. 
     In another alternative embodiment, it is contemplated that first and second thumb wheels may be provided along the handle portion for moving the first and second follower members. The interaction between the thumb wheels and the follower members preferably employs a rack and pinion system of the type known in the art. This embodiment provides the physician with even greater control over the position of the suture arms and needles. 
       FIGS. 23-27  illustrate an alternative embodiment of a suturing apparatus  300 , wherein the release button  108  is provided along the side, rather than extending axially from the proximal end, of the main housing  102 . The suturing apparatus  300  generally comprises an elongate body  32  and an introducer head  20  as described above, and a handle portion  100 ′ as described further below. 
     As shown in  FIG. 23 , the handle portion  100 ′ comprises a main housing  102 , an arm trigger  104  and a needle trigger  106  as described above, and an arm release button  108 ′. The arm trigger, needle trigger and arm release button  108 ′ preferably include markings to indicate the order in which the triggers are actuated, e.g., the arm trigger  104  is labeled “1,” the needle trigger  106  is labeled “2,” and the arm release button  108 ′ is labeled “3.” 
     As shown in  FIG. 24 , the arm and needle triggers are preferably pivotally coupled to the main housing  102  about pin  110  such that the triggers rotate as they are depressed by the physician. When the arm needle trigger  104  is depressed, it engages a first follower member  140 ′ that is slidably received in the main housing  102 . The first follower member  140 ′, shown more particularly in  FIGS. 25 and 26 , comprises an elongate body  302  having a proximal end  304  and a distal end  306  with a slot  308  extending longitudinally through the elongate body along a top side thereof. At the proximal end  304 , the elongate body  302  has a partially circular cross-section, with a proximal portion  310  of the slot receiving the arm trigger  104  when depressed. In an intermediate portion of the elongate body  302 , an intermediate portion  312  of the slot is provided that partially receives the needle trigger  106  when depressed. In a distal portion of the elongate body  302 , a distal portion  314  of the slot is provided that partially receives the needle trigger  106  when depressed, and also receives the second follower member  150 , as described further below. Along both sides of the elongate body adjacent the slot portions  312  and  310 , longitudinal grooves  316  are provided to receive an arm lockout wire  330 , described further below. An inclined ramp  142 ′ such as described above is provided within the portion  310  of the slot to engage the arm trigger  104 . 
     A drive wire tab  156  as illustrated also in the embodiments above is preferably secured to the distal end of the first follower member  140 ′, such as by pins through holes  158 . The tab  156  is secured to the actuating rod  58 , which extends through the central lumen  182  of extrusion clamp  180 . 
       FIG. 27  illustrates the handle  100 ′ with the first follower member  140 ′ removed. A downwardly extending leg  336  extends from a lower surface of the needle trigger  106 . When the first follower member  140 ′ is in its initial configuration, a ledge  338  on the first follower member, shown in  FIG. 26 , is positioned below the leg  336 , preventing the needle trigger  106  from being depressed. When the first follower member  140 ′ is moved proximally, the ledge  338  also moves proximally to allow downward movement of the needle trigger  106 . This prevents the needle trigger  106  from being actuated until after the arms are deployed by depressing arm trigger  104 . 
     The needle trigger  106 , when depressed, engages a cammed surface  152  of second follower member  150 , causing the second follower member  150  to compress needle biasing spring  154 , as described above. The second follower member  150  is provided in the distal portion  314  of the slot  308  and is capable of sliding relative to the first follower member. Proximal of the first follower member  140 ′ is an arm spring  144 , and proximal of arm spring  144  is third follower member  320 , which has an inclined surface  322  which engages arm release button  108 ′. Third follower member has longitudinal grooves  324  on both sides thereof to receive the arm lockout wire  330  described below. Elongate member  108 A′ extends distally from the third follower member  320  underneath the arm spring  144 . 
     As shown in  FIG. 24 , an arm lockout wire  330  extends proximally from the one side of the second follower member  150 , through the longitudinal groove  316  on one side of the elongate body  302  of the first follower member  140 ′, through the longitudinal groove  324  on one side of the third follower member  320 , around the proximal end of the third follower member, and back through the grooves  324  and  316  on the opposite side of the housing and connecting with the second follower member  150 . When second follower member  150  moves distally, arm lockout wire  330  also moves distally, and becomes positioned underneath the arm release button  108 ′. This prevents the arm release button  108 ′ from being depressed while the needles are being actuated, until the second follower member returns to its initial position. 
     As shown in  FIG. 23 , the main housing of the handle portion  100 ′ includes a safety opening or window  112  as described above for manually retracting the needles. The main housing also includes a safety opening or window  113  for manually retracting the arms. The opening  112  cooperates with the opening  332  in second follower member  150 , allowing for a pin to be inserted into the openings to manually bring the second follower member back to its initial configuration. The opening  113  cooperates with the opening  334  in the first follower member  140 ′ for the same purpose. 
     Operation of the suturing assembly  300  as illustrated in  FIGS. 23-27  first begins, after appropriate placement of the assembly, by depressing arm trigger  104  labeled “1”. Depressing arm trigger  104  causes the first follower member  140 ′ to move proximally within the housing  102 , compressing arm spring  144  and moving actuating rod  58  to deploy the arms  24 ,  24 ′ described above. Arm trigger  104  preferably can be depressed until it is secured or locked in a down position, such as described with the embodiment of  FIG. 7  above. 
     Next, depressing needle trigger  106  labeled “2” causes the second follower member  150  to slide distally within the slot of first follower member  140 ′, compressing the needle biasing spring  154  and causing needles  70  and  70 ′ to splay outward from the elongated body  32 . The needle trigger  106  may be configured such as described with respect to  FIG. 16  above. More particularly, the needle trigger  106  may have pins  208 ,  210  that ride initially along an inclined surface of the second follower member  150 , thereby causing the follower member to move in a distal direction for extending the needles. As the needle trigger  106  reaches a finish (i.e., fully depressed) position, the pins extend beyond the bottom edge of the inclined surface, thereby relieving the force on the follower member and allowing the follower member to snap back in a proximal direction. This occurs while maintaining the needle trigger in the fully depressed condition. Accordingly, the needles are first fully extended and then automatically snap back when the needle trigger reaches a first finished position (i.e., is fully depressed). 
     In the embodiment of  FIGS. 23-27 , the needle trigger may remain in its depressed configuration after the second follower member  150  snaps back to its original configuration, or the needle trigger may automatically return to its initial configuration. If the needle trigger  106  does not automatically return to its initial configuration, the operator may simply pull the needle trigger upward along the body of the second follower member, spreading the gap between the pins  208 ,  210  until the pins are once again above the inclined surface. 
     To retract the arms  24 ,  24 ′, the operator presses down on the arm release button  108 ′, labeled “3”. This causes the third follower member  320  to move distally, and causes the elongate member  108 A′ to contact a corner portion of the arm trigger  104  and urge the arm trigger distally so that it is released from the first follower member  140 ′. 
     It should be understood that certain variations and modifications of the above-discussed methods and apparatus will suggest themselves to one of ordinary skill in the art. The scope of this disclosure is not to be limited by the illustrations or the foregoing descriptions thereof, but rather solely by the appended claims.