Abstract:
An instrument for performing thorascopic repair of heart valves includes a shaft for extending through the chest cavity and into a heart chamber providing access to a valve needing repair. A movable tip on the shaft is operable to capture a valve leaflet and a needle is operable to penetrate a capture valve leaflet and draw the suture therethrough. The suture is thus fastened to the valve leaflet and the instrument is withdrawn from the heart chamber transporting the suture outside the heart chamber. The suture is anchored to the heart wall with proper tension as determined by observing valve operation with an ultrasonic imaging system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on U.S. Provisional Patent Application Ser. No. 60/645,677 filed on Jan. 21, 2005 and entitled “THORASCOPIC HEART VALVE REPAIR METHOD AND APPARATUS.” 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Various types of surgical procedures are currently performed to investigate, diagnose, and treat diseases of the heart and the great vessels of the thorax. Such procedures include repair and replacement of mitral, aortic, and other heart valves, repair of atrial and ventricular septal defects, pulmonary thrombectomy, treatment of aneurysms, electrophysiological mapping and ablation of the myocardium, and other procedures in which interventional devices are introduced into the interior of the heart or a great vessel. 
         [0003]    Using current techniques, many of these procedures require a gross thoracotomy, usually in the form of a median sternotomy, to gain access into the patient&#39;s thoracic cavity. A saw or other cutting instrument is used to cut the sternum longitudinally, allowing two opposing halves of the anterior or ventral portion of the rib cage to be spread apart. A large opening into the thoracic cavity is thus created, through which the surgical team may directly visualize and operate upon the heart and other thoracic contents. 
         [0004]    Surgical intervention within the heart generally requires isolation of the heart and coronary blood vessels from the remainder of the arterial system, and arrest of cardiac function. Usually, the heart is isolated from the arterial system by introducing an external aortic cross-clamp through a sternotomy and applying it to the aorta between the brachiocephalic artery and the coronary ostia. Cardioplegic fluid is then injected into the coronary arteries, either directly into the coronary ostia or through a puncture in the aortic root, so as to arrest cardiac function. In some cases, cardioplegic fluid is injected into the coronary sinus for retrograde perfusion of the myocardium. The patient is placed on cardiopulmonary bypass to maintain peripheral circulation of oxygenated blood. 
         [0005]    Of particular interest to the present invention are intracardiac procedures for surgical treatment of heart valves, especially the mitral and aortic valves. According to recent estimates, more than 79,000 patients are diagnosed with aortic and mitral valve disease in U.S. hospitals each year. More than 49,000 mitral valve or aortic valve replacement procedures are performed annually in the U.S., along with a significant number of heart valve repair procedures. 
         [0006]    Various surgical techniques may be used to repair a diseased or damaged valve, including annuloplasty (contracting the valve annulus), quadrangular resection (narrowing the valve leaflets), commissurotomy (cutting the valve commissures to separate the valve leaflets), shortening mitral or tricuspid valve chordae tendonae, reattachment of severed mitral or tricuspid valve chordae tendonae or papillary muscle tissue, and decalcification of valve and annulus tissue. Alternatively, the valve may be replaced, by excising the valve leaflets of the natural valve, and securing a replacement valve in the valve position, usually by suturing the replacement valve to the natural valve annulus. Various types of replacement valves are in current use, including mechanical and biological prostheses, homografts, and allografts, as described in Bodnar and Frater, Replacement Cardiac Valves 1-357 (1991), which is incorporated herein by reference. A comprehensive discussion of heart valve diseases and the surgical treatment thereof is found in Kirklin and Barratt-Boyes, Cardiac Surgery 323-459 (1986), the complete disclosure of which is incorporated herein by reference. 
         [0007]    The mitral valve, located between the left atrium and left ventricle of the heart, is most easily reached through the wall of the left atrium, which normally resides on the posterior side of the heart, opposite the side of the heart that is exposed by a median sternotomy. Therefore, to access the mitral valve via a sternotomy, the heart is rotated to bring the left atrium into a position accessible through the sternotomy. An opening, or atriotomy, is then made in the left atrium, anterior to the right pulmonary veins. The atriotomy is retracted by means of sutures or a retraction device, exposing the mitral valve directly posterior to the atriotomy. One of the fore mentioned techniques may then be used to repair or replace the valve. 
         [0008]    An alternative technique for mitral valve access may be used when a median sternotomy and/or rotational manipulation of the heart are undesirable. In this technique, a large incision is made in the right lateral side of the chest, usually in the region of the fifth intercostal space. One or more ribs may be removed from the patient, and other ribs near the incision are retracted outward to create a large opening into the thoracic cavity. The left atrium is then exposed on the posterior side of the heart, and an atriotomy is formed in the wall of the left atrium, through which the mitral valve may be accessed for repair or replacement. 
         [0009]    Using such open-chest techniques, the large opening provided by a median sternotomy or right thoracotomy enables the surgeon to see the mitral valve directly through the left atriotomy, and to position his or her hands within the thoracic cavity in close proximity to the exterior of the heart for manipulation of surgical instruments, removal of excised tissue, and/or introduction of a replacement valve through the atriotomy for attachment within the heart. However, these invasive, open-chest procedures produce a high degree of trauma, a significant risk of complications, an extended hospital stay, and a painful recovery period for the patient. Moreover, while heart valve surgery produces beneficial results for many patients, numerous others who might benefit from such surgery are unable or unwilling to undergo the trauma and risks of current techniques. 
         [0010]    The mitral and tricuspid valves inside the human heart include an orifice (annulus), two (for the mitral) or three (for the tricuspid) leaflets and a subvalvular apparatus. The subvalvular apparatus includes multiple chordae tendinae, which connect the mobile valve leaflets to muscular structures (papillary muscles) inside the ventricles. Rupture or elongation of the chordae tendinae result in partial or generalized leaflet prolapse, which causes mitral (or tricuspid) valve regurgitation. A commonly used technique to surgically correct mitral valve regurgitation is the implantation of artificial chordae (usually 4-0 or 5-0 Gore-Tex sutures) between the prolapsing segment of the valve and the papillary muscle. This operation is generally carried out through a median sternotomy and requires cardiopulmonary bypass with aortic cross-clamp and cardioplegic arrest of the heart. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention is a method and apparatus for performing a minimally invasive thoracoscopic repair of heart valves while the heart is beating. More specifically the method includes inserting an instrument through the subject&#39;s chest wall and through the heart wall. The instrument carries on its distal end a movable element which is manipulated to grasp a valve leaflet and hold it while a needle mechanism punctures the valve leaflet and loops a suture around a portion of the valve leaflet. The instrument is withdrawn from the heart along with the suture and the suture is tied off at the apex of the heart after adjusting its tension for optimal valve operation as observed with an ultrasonic imaging system. 
         [0012]    In addition to grasping and needle mechanisms, the instrument includes fiber optics which provide direct visual indication that the valve leaflet is properly grasped. A set of illuminating fibers terminate at the distal end of the instrument around the needle mechanism in close proximity to a set of sensor fibers. The sensor fibers convey light from the distal end of the instrument to produce an image for the operator. When a valve leaflet is properly grasped, light from the illuminating fibers is reflected off the leaflet surface back through the sensor fibers. On the other hand, if the valve leaflet is not properly grasped the sensor fibers see blood. 
         [0013]    A general object of the invention is to provide an instrument and procedure which enables heart valves to be repaired without the need for open heart surgery. The instrument is inserted through an opening in the chest wall and into a heart chamber while the heart is beating. The instrument enables repair of a heart valve, after which it is withdrawn from the heart and the chest. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    Under general anesthesia and double-lumen ventilation, the patient is prepped and draped so as to allow ample surgical access to the right lateral, anterior and left lateral chest wall (from the posterior axillary line on one side to the posterior axillary line on the other side). As shown in  FIG. 1 , one or more thoracoscopic ports are inserted in the left chest through the intercostal spaces and an instrument  10  is inserted through one of these ports into the chest cavity. Alternatively, a small (3-5 cm) left thoracotomy is performed in the fifth or sixth intercostals space on the anterior axillary line. The patient is fully heparinized. After collapsing the left lung, the pericardium overlying the apex  12  of the left ventricle  14  is opened and its edges are suspended to the skin incision line. This provides close access to the apex of the heart. Guidance of the intracardiac procedure is provided by a combination of transesophageal or intravascular echocardiography (not shown in the drawings) and with direct visualization through a fiber-optical system built into the instrument  10  as will be described in detail below. A double-pledgeted purse-string suture is placed on the apex of the left ventricle  12  and a stab incision is made at that location. The surgical instrument  10  is inserted through this incision, into the left ventricular chamber  14  of the beating heart. 
         [0015]    Referring particularly to  FIG. 2 , the instrument  10  may be used to grasp a prolapsing segment of the mitral valve  16  and an artificial chorda  18  may be secured to its free edge. Accurate positioning of the implanted artificial chorda  18  is guaranteed by both echo and direct fiberoptic visualization as will be described in detail below. The instrument  10  is then withdrawn from the left ventricle chamber  14  pulling the unattached end of the neo-implanted chorda  18  with it. Hemostasis is achieved by tying the purse-string suture around the incision in the left ventricular apex  12  after the instrument  10  and chorda  18  are withdrawn. As shown in  FIG. 3 , the neo-implanted chorda  18  is appropriately tensioned under direct echo-Doppler visualization and secured outside the apex  12  of the heart. That is, a tension is placed on the neo-implanted chorda  18  and the operation of the repaired valve  16  is observed on the ultrasound image. The tension is adjusted until regurgitation is minimized. 
         [0016]    While a single chorda  18  is implanted in the above description, additional chorda, or sutures, can be implanted and attached to the apex  12  of the heart wall with optimal tension. In this case the tensions in all the neo-implanted chorda  18  are adjusted until optimal valve operation is achieved. 
         [0017]    As shown in  FIGS. 4 and 5 , the instrument  10  used to perform the above procedure includes a rigid metal shaft  100  having a handle  120  at its extrathoracic (proximal) end which enables the instrument to be manipulated and guided into position. Actuating mechanisms for controlling the grasping mechanism and needle mechanism located at the distal end  140  of the instrument are also mounted near the handle  120 . As will be described below, the grasping mechanism is operated by squeezing the scissor-grip handle  120 , and the needle mechanism is operated by moving an up-turned control shaft  122 . 
         [0018]    Located on the distal, intracardiac end  140  of the instrument  10  is a grasping mechanism which can be operated to hold a prolapsing valve leaflet. As shown in  FIGS. 6 and 7 , in the preferred embodiment this mechanism is a tip  160  which is supported on the distal end of the shaft  100  by a set of rods  162 . The rods  162  slide within the shaft  100  to move the tip  160  between an open position as shown in  FIGS. 6B and 7  and a closed position as shown in  FIG. 6A  when the scissor-grip handle  120  is operated. As will be explained below, a mitral valve leaflet is located in the gap between the open tip  160  and the distal end of shaft  100  and it is captured by closing the tip  160  to pinch the valve leaflet therebetween. 
         [0019]    Disposed in a needle lumen  164  formed in the shaft  100  is a needle  180  which connects to the control shaft  122  at the proximal end of shaft  100 . Needle mechanism  180  slides between a retracted position in which it is housed in the lumen  164  near the distal end of the shaft  100  and an extended position in which it extends into the sliding tip  160  when the tip is in its closed position. As a result, if a valve leaflet has been captured between the tip  160  and the distal end of shaft  100  the needle may be extended from the lumen  164  by moving control shaft  122  to puncture the captured leaflet and pass completely through it. 
         [0020]    The distal end of the shaft  100  also contains an artificial chorda, or suture  18  that is to be deployed in the patient&#39;s heart. The suture  18  is typically a 4-0 or 5-0 suture manufactured by a company such as Gore-Tex. This suture  18  is deployed by the operation of the grasping mechanism and the needle mechanism  180  as described in more detail below. 
         [0021]    The shaft  100  has a size and shape suitable to be inserted into the patient&#39;s chest and through the left ventricle cardiac wall and form a water-tight seal with the heart muscle. It has a circular or ellipsoidal cross-section and it houses the control links between the handle end and the intracardiac end of the instrument as well as a fiber optic visualization system described in more detail below. 
         [0022]    As shown in  FIGS. 8A-8F , the preferred embodiment of the suture deployment system at the distal end of the instrument  10  is positioned around a valve leaflet  16  to be repaired as shown in  FIG. 8A . The suture  18  is folded at the middle to form a loop  19  that is positioned in the tip  160 . Both ends of the suture  18  are disposed in a suture lumen  165  formed in the shaft  100  beneath the rods  162 . As shown in  FIG. 8B , the valve leaflet  16  is grasped by closing the tip  160 , and the needle  180  is extended to puncture the leaflet  16  and extend into the tip  160 . A notch  166  formed on one side of the needle  180  hooks the suture loop  19 . The needle  180  is then retracted back through the leaflet  16  to pull the suture loop  19  through the puncture opening as shown in  FIG. 8C . The leaflet  16  is then released and the instrument  10  is withdrawn from the heart as shown in  FIG. 8D  pulling both ends and the midpoint of the suture  18  with it. As shown in  FIG. 8E , the suture  18  is released by the instrument  10  and the surgeon inserts the two suture ends  21  through the loop  19  at its midpoint. The ends  21  are then pulled and the loop  19  slides along the suture  18  back into the heart chamber  14  where it forms a Larks head around the edge of the valve leaflet as shown in  FIG. 8F . 
         [0023]    Multiple sutures  18  may be implanted in this manner until a satisfactory result is obtained. After deployment of the sutures  18 , the heart wall incision is repaired by either a pre-positioned purse-string suture or by any kind of appropriate hemostatic device or technique. Hemostasis is checked, appropriate chest drainage tubes are positioned and secured, and all incisions are closed. 
         [0024]    As shown in  FIGS. 9A-9D , a second embodiment of the suture deployment system at the distal end of the instrument  10  is positioned around a valve leaflet  16  to be repaired as shown in  FIG. 9A . The suture  18  in this embodiment is a closed loop with one end of the loop disposed in the tip  160  and its other end disposed in the lumen  164  and wrapped around the needle  180 . The needle  180  is extended through the grasped valve leaflet  16  into the instrument tip  160  where it hooks one end of the looped suture  18  in a notch  166  formed on one side of the needle as shown in  FIG. 9B . The needle  180  is then retracted to pull the the looped suture  18  through the puncture opening in the leaflet  16 . The leaflet is then released as shown in  FIG. 9C  by sliding the tip  160  to its open position. The instrument  10  is then withdrawn as shown in  FIG. 9D  to slide the unhooked end of the looped suture  18  along the length of the needle toward the leaflet  16  where it forms a Larks head around the leaflet edge. 
         [0025]    The instrument  10  is then withdrawing from the heart chamber  14  pulling the hooked end of the suture  18  through the heart wall. The suture  18  is secured to the outside of the heart apex. 
         [0026]    As shown in  FIGS. 10A-10D , a third embodiment of the suture deployment system at the distal end of the instrument  10  is positioned around a valve leaflet  16  to be repaired as shown in  FIG. 10A . The midpoint  17  of the suture  18  is looped around the lumen  164  and its two loose ends  20  are coiled up in the tip  160 . After the tip  160  is closed to capture the valve leaflet  16 , the needle  180  is extended through the grasped valve leaflet  16  into the instrument tip  160 . The free ends  20  of the suture  18  are positioned in the tip  160  to form a loop  19  and a notch  166  formed on one side of the needle extends through this loop  19  and “hooks” the free ends of the suture  18  as shown in  FIG. 10B . The needle  180  is then retracted back into the lumen  164  to pull the hooked ends of the suture  18  through the puncture opening in the leaflet  16 . The leaflet is then released as shown in  FIG. 10C  by sliding the tip  160  to its open position. The instrument  10  is then withdrawn from the heart as shown in  FIG. 10D  to pull the free ends  20  back through the valve leaflet  16  and a Larks head is formed around the leaflet edge by the midpoint  17  of the suture  18 . 
         [0027]    The instrument  10  is then withdrawn from the heart chamber  14  pulling the free ends  20  of the suture  18  through the heart wall. The free ends  20  of the suture  18  are secured to the outside of the heart apex. 
         [0028]    Other suture deployment systems are possible where, for example, the needle may penetrate through the leaflet and link up with a snap fitting device that is attached to one end of the looped suture  18  in the instrument tip  160 . The needle then withdraws pulling the device and looped suture back through the penetration opening in the leaflet as described above. 
         [0029]    As shown in  FIG. 7  to enhance visibility during this procedure, four fiberoptic channels  170  extend along the length of the instrument shaft  100  and terminate at its distal end. Each channel  170  contains at least one illuminating fiber which connects at its extrathoracic end to a white light source (not shown in the drawings). Each channel  170  also contains at least one sensor fiber which conveys reflected light from the distal end back to a visualization monitor (not shown in the drawings) connected to its extrathoracic end. In the preferred embodiment each channel  170  includes two illuminating fibers and two sensor fibers. 
         [0030]    The four fiberoptic channels  170  are disposed around the needle lumen  164  such that when a valve leaflet  16  is properly grasped, the valve leaflet tissue  16  rests against the distal end of all the fibers  170 . As a result, light is reflected off the tissue back into the sensor fibers and four white circles are displayed on the visualization monitor. When the leaflet  16  is not properly pressed against the distal end of a channel  170 , light is not reflected from the leaflet  16  and the visualization monitor displays the red color reflected from blood. When no valve tissue is captured, the monitor shows four red dots and when valve tissue is captured, the dots corresponding to the fiberoptic channels  170  contacting the tissue turn white. If the monitor shows all four dots as white, it means that the valve tissue capture is optimal. If only the upper two dots turn white and the bottom dots remain red, the “bite” on the valve leaflet  16  is too shallow for a proper attachment of the suture  18 . 
         [0031]    In addition to the fiberoptic visualization system that insures that a valve leaflet is properly captured, other real-time visualization systems are employed to help guide the instrument  10  to the valve leaflet  16 . Preferably a transesophageal or intravascular color-Doppler echocardiography system is used for this purpose. As explained above, this imaging system is also used to determine the length of the neo-implanted artificial chordae in real-time by observing reduction or disappearance of regurgitation by transesophageal or intravascular color-Doppler echocardiography.