Abstract:
The invention describes a method of treating a patient&#39;s left atrial appendage through the pericardial space. The process takes place through the pericardial space from an access point outside the pericardium or pericardial space.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to devices and techniques for remodeling the atrial appendage of a mammal. The process takes place through the pericardial space from an access point outside the pericardium or pericardial space.  
         BRIEF DESCRIPTION OF THE PRIOR ART  
         [0002]    The atrial appendage is an anatomic feature of the left atrium of the human heart. It is widely believed that atrial fibrillation results in a pooling of blood in the atrial appendage which results in clots.  
           [0003]    The surgical removal of the atrial appendage through a limited thoracotomy has been proposed by Johnson in U.S. Pat. No. 5,306,234. However, the surgical removal of the appendage remains problematic since the surgical intervention occurs under general anesthesia and is considered major surgery. It should also be realized that even a transluminal minimally invasive approach from inside the heart is problematic since such an approach requires an implantable closure device and has the risk of acute stroke. Typically any closure device left in contact with the interior of the heart is potentially a thromobogenic surface.  
           [0004]    For these reasons among others there is a continuing need to improve techniques for occluding or removing the left atrial appendage.  
         SUMMARY  
         [0005]    In contrast to the prior art, the present invention teaches devices and methods of using the devices to remodel the atrial appendage from locations outside the heart but within the pericardial space. In use, the pericardial space is accessed via the chest wall below the rib cage and an endoscope is inserted. It is preferred to perform the process steps under visual guidance although robotic and other location technologies may be used in the alternative. The preferred treatment for the appendage is “wet cautery” where the size and therefore the volume of the appendage is reduced. An alternate preferred device cuts and cauterizes while removing the appendage. Other surgical techniques are useful as well including conventional electrosurgery and cautery and conventional suture and staple techniques. In all instances the volume of the appendage is reduced and in some approaches tissue is removed as well. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The invention is illustrated in the figures where like reference numeral represent identical structure throughout the several views wherein:  
         [0007]    [0007]FIG. 1 is a schematic diagram of the patient&#39;s chest cavity;  
         [0008]    [0008]FIG. 2 is a schematic diagram of pericardial access process and device;  
         [0009]    [0009]FIG. 3 is a schematic diagram of pericardial space visualization process and device;  
         [0010]    [0010]FIG. 4 is a schematic diagram of pericardial space electrocautery process and device;  
         [0011]    [0011]FIG. 5 is a schematic diagram of an electrocautery process and device;  
         [0012]    [0012]FIG. 6 is a schematic diagram of an electrocautery process and device;  
         [0013]    [0013]FIG. 7 is a schematic diagram of an endoscopic suture placement process; and  
         [0014]    [0014]FIG. 8 is a schematic diagram of an endoscopic staple placement process. 
     
    
     DETAILED DESCRIPTION  
       [0015]    [0015]FIG. 1 shows the patients heart  10  located within the patient&#39;s chest cavity  12 . The ribs  14  and skin  16  show the boundary of the chest cavity  12 . The left atrial appendage (LAA)  18  is exaggerated in size to facilitate the description of the invention. The heart  10  chambers lie within the so-called pericardium  20 , which is shown in an exaggerated scale. The pericardium  20  is a bag like structure that surrounds the heart. It is attached to the great vessels at the “top” of the heart and it completely encircles the ventricles and the atrium of the heart. The pericardium  20  provides a low friction surface surrounding the heart that permits motion of the heart. In essence the pericardium allows the heart to “beat” without disturbing other near-by organs.  
         [0016]    The processes of the invention permit the pericardium to remain “intact”. Although several opening to the pericardial space are illustrated it is emphasized that the smaller the number of “holes” in the pericardium are preferred.  
         [0017]    [0017]FIG. 2 shows initial access to the pericardial space though the use of a pericardial access device  22 , which is described in more detail in U.S. Pat. No. 5,827,216 among others. This patent is incorporated by reference herein and the commercially available device is sold under the trademark “Perducer”. The Perducer is preferred but alternate devices such as that taught by U.S. Pat. No. 5,931,810 could be freely substituted for the Perducer device. If multiple access points are required for a particular patient the two devices may be used together.  
         [0018]    The preferred device  22  has an aperture at its distal end  24  that allows aspiration of the pericardium  20  into the device. An illustrative source of vacuum is shown as the physician operated syringe  26 . The aspirated tissue drawn into the device  22  can be pierced by the needle  28 . The needle  28  can be translated toward the aspirated tissue by pushing on the proximal end of the needle  28 .  
         [0019]    A guidewire  30  can next be inserted through the lumen of the needle  28 . With the guidewire in the pericardial space, the physician can withdraw the needle and use the guidewire to insert a catheter or other device. The access procedure described may be repeated to provide for multiple access sites or locations into the pericardial space. Although the device shown is preferred it should be recognized that other devices may be used as well.  
         [0020]    [0020]FIG. 3 shows two access sites labeled  50  and  52  respectively. A guide catheter  40  has been introduced into the pericardial space  42 . This access site or port permits access by the endoscope  46  which includes a camera  48  and a display system  52 . Together these devices provide a visualization system allows visual navigation and manipulation of additional surgical tools in the pericardium  20 . Although this visualization system is not seen in the remaining drawings its use should be presumed and the deletion from the figure is done to clarify the remaining drawings. It should be noted that most conventional endoscopes in use today have laparoscopic tool access ports built into the device and many steps of the invention can be carried out trough the scope rather than through a separate access site. However, it is expected that a typical atrial appendage reduction would require two sites, with one devoted to the introduction of a endoscope.  
         [0021]    [0021]FIG. 4 shows a snare like electrocautery tool  60  introduced into the pericardial space  42 . The distal loop  64  has been navigated visually to “lasso” the atrial appendage. In the device seen in FIG. 4, one end of the snare loop  64  is attached to a tubular body  63  while the other end is carried through the lumen of the tubular body  63  and attached to a sliding handle  15 . A fixed handle  17  is attached to the tubular body  63 . Traction applied to the snare loop  64  by moving the sliding handle relative to the fixed handle  17  captures the appendage  18 . The application of electrical energy (RF) from the electrocautery unit  70  can either remove or close the atrial appendage. It is important to note that this closure process may be essentially bloodless and may be performed under direct visualization through the endoscope (FIG. 3). This process is an example of “dry” cautery as opposed to “wet” cautery described in connection with FIG. 6. Although the snare like device is preferred there are several commercially available products that can also be used for this step including the loop excision electrodes sold by ValleyLab of Colorado. In general, any specific surgeon may prefer to use other familiar tools for the process. Typically, the electrosurgery unit  70  will be connected between the loop  64  and a patient ground depicted as  71 . The physician may activate the hand or foot switch  73  to dissect the appendage.  
         [0022]    [0022]FIG. 5 shows the snare loop  64  isolating the atrial appendage  18  prior to the applicant of electrical energy. In the figure the physician my grasp an insulator handle and the connection  19  may not be attached to the generator  70  until after the lasso procedure has been accomplished. Although the loop electrocautery device is preferred it should be noted that the conventional unipolar or bipolar cautery scissors such as those illustrated as device  13  may be used to cut off the appendage.  
         [0023]    [0023]FIG. 6 shows the use of “wet” electrocautery to “reduce” the atrial appendage. In this procedure the electrical catheter  80  is irrigated by a fluid flow of saline or other conductive fluid  81 . This wet electrode applies the energy over a wider surface area as a consequence heat is supplied preferentially to the LAA. It is expected that the application of heat will cause the appendage to reduce in size substantially. Fluid assisted electrocautery is known from U.S. Pat. No. 6,063,081 among others.  
         [0024]    [0024]FIG. 7 shows an alternate method of closing off the atrial appendage. In this situation a suture  90  has been formed into a loop  92  and passed over the atrial appendage. A laparoscopic knot pusher  94  is passed down one leg of the suture  90  to place and tighten a knot formed in the suture. The use of a suture may be preferred given the size and shape of the appendage  18 .  
         [0025]    [0025]FIG. 8 illustrates an alternate closure device and process. In this figure a laparoscopic stapler is used to place one or more staples to close off the atrial appendage. In the figure the tool  98  has been used to place one staple seen as staple  97  closing off the appendage.