Abstract:
A membrane applied to the ostium of an atrial appendage for blocking blood from entering the atrial appendage which can form blood clots therein is disclosed. The membrane also prevents blood clots in the atrial appendage from escaping therefrom and entering the blood stream which can result in a blocked blood vessel, leading to strokes and heart attacks. The membranes are percutaneously installed in patients experiencing atrial fibrillations and other heart conditions where thrombosis may form in the atrial appendages. A variety of means for securing the membranes in place are disclosed. The membranes may be held in place over the ostium of the atrial appendage or fill the inside of the atrial appendage. The means for holding the membranes in place over the ostium of the atrial appendages include prongs, stents, anchors with tethers or springs, disks with tethers or springs, umbrellas, spiral springs filling the atrial appendages, and adhesives. After the membrane is in place a filler substance may be added inside the atrial appendage to reduce the volume, help seal the membrane against the ostium or clot the blood in the atrial appendage. The membranes may have anticoagulants to help prevent thrombosis. The membranes may be porous such that endothelial cells cover the membrane presenting a living membrane wall to prevent thrombosis. The membranes may have means to center the membranes over the ostium. Sensors may be attached to the membrane to provide information about the patient.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of commonly-assigned application Ser. No. 09/428,008, filed Oct. 27, 1999, now U.S. Pat. No. 6,551,303. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a membrane or plug structure applied to the ostium of an atrial appendage for preventing blood flow and physical connection between an atrium of the heart and the associated atrial appendage or appendages to isolate an atrial appendage and prevent thrombus leaving therefrom. 
     2. Description of the Related Art 
     There are a number of heart diseases (e.g. coronary artery disease, mitral valve disease) that have various adverse effects on the heart. An adverse effect of certain cardiac diseases, such as mitral valve disease, is atrial (or auricular) fibrillation. Atrial fibrillation may result in pooling of blood in the left atrial appendage. Blood pooling may also be spontaneous. When blood pools in the atrial appendage, blood clots can form and accumulate therein, build upon themselves, and propagate out from the atrial appendage into the atrium. These blood clots can then enter the systemic or pulmonary circulations and cause serious problems if they migrate from the atrial appendage and become free in the blood stream and embolize distally into the arterial system. Similar problems also occur when a blood clot extending from an atrial appendage into an atrium breaks off and enters the blood supply. Since blood from the left atrium and ventricle supply the heart and brain, blood clots from the atria appendages can obstruct blood flow therein causing heart attacks, strokes or other organ ischemia. It is therefore necessary to find a means of preventing blood clots from forming in the atrial appendages and to prevent these blood clots, once formed, from leaving the atrial appendages to the heart lungs, brain or other circulations of the patient which can cause heart attacks or strokes or other organ ischemia. 
     U.S. Pat. No. 5,865,791 relates to the reduction of regions of blood stasis and ultimately thrombus formation in such regions, particularly in the atrial appendages of patients with atrial fibrillation. More specifically, the invention relates to procedures and devices for affixing the atrial appendages in an orientation that prevents subsequent formation of thrombus. The invention removes the appendage from the atrium by pulling on it and putting a loop around it to form a sack of the atrial appendage and then cut off from the rest of the heart. 
     U.S. Pat. No. 5,306,234 relates to a method for surgically closing the passage between the atrium and the atrial appendage or severing the atrial appendage. 
     Other methods of treatment include surgically removing the atrial appendages to prevent blood stasis in the atrial appendages. 
     SUMMARY OF THE INVENTION 
     The invention provides a membrane or plug structure for preventing blood from entering the atrial appendages to form blood clots and prevents blood clots formed in the atrial appendages from exiting therefrom which may cause heart attacks, strokes and other embolic events. The membrane covers the ostium of the atrial appendage and effectively isolates it from the atrium. It may be larger than the ostium of the appendage, and extend over an area larger than the appendage ostium. It is percutaneously delivered to the ostium of the atrial appendage by a catheter and then expanded to cover the ostium and has a means to attach the membrane over the ostium. The membrane itself may be porous or non-porous. In the case of a porous membrane, it can become infiltrated with cells so that it becomes a “living” structure, and can develop an endothelial/endocardial lining to enable it in turn to become a non-thrombogenic surface. There are many means for fixing the membrane to cover the ostium of the atrial membrane. The membrane&#39;s attachment devices have a means for self-centering the membrane over the appendage ostium. The membrane may be glued on, or have a stents or prongs which pass through the ostium and extend into or through the atrial appendage. Alternatively an anchor in the wall of the atrial appendage may be tethered to the membrane for holding the membrane in place. Springs may also extend between the anchor and the membrane to hold the membrane against the ostium. The membrane may also be connected to a tether, elastic tether or spring and placed through the atrial appendage wall for holding the membrane against the ostium and may pull on the atrial appendage such that its volume is reduced or eliminated, trapping and isolating blood clots therein. Thrombin, activated fibrinogen, or other biologic filler may be placed in the appendage after it has been sealed, with the express purpose of clotting the blood in the appendage, yet preventing clots from escaping the appendage. 
     Part of the device may involve a suction apparatus to remove clots that are already in place. The membrane placement may require closure of an atrial septal defect created by the placement of this appendage occluder device. 
     Alternatively the membrane may be held in place by a coiled spring filling the volume of the atrial appendage. The membrane may also fill the atrial appendage itself preventing blood from entering or blood clots from leaving. 
     The membrane itself may be porous or non-porous. In the case of a porous membrane, it can become infiltrated with cells so that it becomes a “living” structure, and can develop an endothelial/endocardial lining to enable it in turn to become a non-thrombogenic surface. It thus can develop an endothelium and with time becomes highly biocompatible. It may be heparin-coated to prevent thrombus from forming on the membrane surface, immediately after placement and until it infiltrates with cells and/or develops an endothelial covering. 
     The device, when implanted in the atrial appendage, may also have the ability to perform electrical monitoring of the heart. This would consist of two or more electrical contacts placed apart on the device, and connected to signal conditioning circuitry for determination of cardiac features such as rhythm of the atria or ventricles. Another sensor on the device could measure pressure of the atrial appendage, or ventricular end diastolic pressures (left or right) through the open mitral or tricuspid valves. A suitable telemetry system would be used to telemeter this important electrical and hemodynamnic information non-invasively outside the patient. Also, memory could be present on the device in order to record the information for later recovery via non-invasive telemetry. 
     This device can also be used to close fistulae or connections elsewhere in the body, such as in the colon or bronchopulmonary systems. Another application of the device would be to seal and strengthen false aneurysms of the left ventricle by holding the membrane against the false aneurysm. The same principles apply, whereby the membrane is held against the fistulae or false aneurysm, held in place by the spring or prong mechanism. 
     The device can also be used to chemically ablate the myocardial tissue of the atrial appendage in order to help limit or eliminate the electrical propagation of atrial fibrillation. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to reduce the volume of an atrial appendage to reduce the size of the region for potential blood stasis formation, and consequently the effective volume of the affected atrium. 
     It is an object of the invention to measure hemodynamics pressure (or flow), or electrical signals in the heart and telemeter them outside the body for diagnosis or monitoring. 
     It is an object of the invention to be able to close fistulae or connections elsewhere in the body, such as in the colon or bronchopulmonary systems. 
     It is another object of the invention for the membrane to be placed in a false aneurysm to strengthen this defect and to avoid surgery. 
     It is an object of the invention to reduce the region of static blood in the atrial appendages and hence the thrombogenicity of the atrium. 
     It is an object of the invention to prevent blood clots from forming in the atrial appendages. 
     It is an object of the invention to replace the ostium of the atrial appendage with a non-thrombogenic, biocompatible surface that prevents blood clots from forming. 
     It is an object of the invention to provide a porous membrane surface which becomes lined with endothelial or endocardial cells. 
     It is an object of the invention to isolate the atrial appendage from the atrium proper and prevent communication through which thrombus could migrate. 
     It is an object of the invention to minimally invasively prevent blood clots from forming in the atrial appendages and escaping therefrom. 
     It is an object of the invention to provide a filter between the atrium and atrial appendage to prevent blood clots from flowing therebetween. 
     It is an object of the invention to fill the atrial appendage with a material to prevent blood clots from leaving the atrial appendage. 
     It is an object of the invention to remove thrombi from the atrium via suction or other means. 
     It is an object of the invention to provide a means for securing a membrane over the ostium of the atrial appendage that is colonized with cells and provide a highly biocompatible surface including but not limited to endothelialization. 
     It is an object of the invention to prevent thrombus by use of heparin or other anti-thrombogenic substance on or eluted from the membrane. 
     It is an object of the invention to seal the membrane with a substance injected into the atrial appendage. 
     It is an object of the invention to clot the blood inside of the atrial appendage after the membrane is in place with a substance injected into the atrial appendage. 
     It is an object of the invention to inject a substance into the sealed appendage to ablate the myocardial cells of the appendage, in order to limit the propagation of atrial fibrillation. 
     It is an object of the invention to ensure the membrane is centered over the ostium of the atrial appendage. 
     It is an object of the invention to accurately place the membrane over the ostium of the atrial appendage. 
    
    
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross sectional view of a heart showing a catheter entering the left atrial appendage using a retrograde procedure from the aorta. 
     FIG. 2 is a partial cross sectional view of a heart showing a catheter entering the left atrial appendage using a transeptal procedure from the femoral vein or superior vena cava. 
     FIG. 3 is a partial cross sectional view of a heart showing a catheter entering the right atrial appendage from the jugular vein or optionally from the femoral vein. 
     FIG. 4 is a partial cross sectional view of a portion of the heart showing an atrium and its associated atrial appendage. 
     FIG. 5 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage with a porous membrane having flexible wire prongs with atraumatic bulbs to hold the membrane in place and electronics built into the membrane. 
     FIG. 6 is similar to FIG. 5 with the atraumatic bulbs removed so that the flexible wire prongs may puncture the atrium wall and secure the membrane to the atrial appendage and a centering rim added to the membrane. 
     FIG. 7 is a partial cross sectional view of a portion of a heart as in FIG. 5 with a stent portion between the membrane and the prongs. 
     FIG. 8 is the same as FIG. 7 with the atraumatic bulbs removed so that the flexible wire prongs may puncture the atrium wall and secure the membrane to the atrial appendage. 
     FIG. 9 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage with a porous membrane having a large expandable stent to hold the membrane in place. 
     FIG. 10 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage having an anchor and a tether to hold the membrane in place. 
     FIG. 11 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage having an anchor and a spring to hold the membrane in place, a centering rim on the membrane and a centering cable. 
     FIG. 12 is the same as FIG. 11 with the spring filling the atrium to help hold the membrane in pace. 
     FIG. 13 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage with the membrane adhesively being held in place. 
     FIG. 14 is a partial cross sectional view of a delivery catheter having a disk, a spring and membrane therein. 
     FIG. 15 is a schematic view of a disk, spring and membrane after being expanded out of the delivery catheter of FIG.  11 . 
     FIG. 16 is a partial cross sectional view of a portion of a heart showing an atrium and its associated trial appendage having a disk, a membrane and a spring therebetween. 
     FIG. 17 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage shown in a collapsed position. 
     FIG. 18 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage having a disk, a spring, a membrane and vacuum in the catheter. 
     FIG. 19 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage having a membrane material filling the atrial appendage. 
     FIG. 20 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage showing an umbrella folded for entering the atrial appendage. 
     FIG. 21 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage showing the umbrella opened in the atrial appendage to secure the umbrella into the wall of the atrial appendage. 
     FIG. 22 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage showing the umbrella and membrane sealing the ostium of the atrial appendage. 
     FIG. 23 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage showing a stent having a membrane for blocking the ostium of the atrial appendage. 
     FIG. 24 is a partial cross sectional view of a portion of a heart showing an atrium and its associated atrial appendage showing the atrial appendage reduced to a minimum volume by a disk and spring squeezing the appendage against a membrane. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Although atrial fibrillation results in pooling of blood in the left atrial appendage and the majority of use of the invention is anticipated to be for the left atrial appendage, the invention may also be used on the right atrial appendage and in general for any aperture in the body which needs to be blocked to prevent blood from flowing therethrough or therefrom. 
     As shown in FIG. 4 a thrombus  30  may occur from pooling of blood in the left atrial appendage  13  due to poor circulation of blood therein when the patient experiences atrial fibrillation. To prevent thrombus  30  from forming in the left atrial appendage  13  or to prevent thrombosis formed therein from leaving and entering the blood stream which may cause a heart attack, a stroke or ischemia, a membrane  40  is placed across the ostium  20  of the atrial appendage  13 . The membrane  40  can be made of Teflon®, felt, Dacron®, silicone urethane, Gortex®, metal fibers or biocompatible polymers. 
     The membrane  40  may be a porous membrane. Porous membranes may consist of a biocompatible polymer which is porous, having pore sizes ranging from 20-100 microns. The pores may also be larger or smaller in rare cases. The membrane may also be a porous metal or a metal mesh of fine fibers which permit ingrowth of cells and covering with endothelial cells. The membrane may be coated with anticoagulant or elute the anticoagulant. 
     The porous membrane colonizes with cells from the heart and so walls off the ostium  20  so that blood can not flow into the left atrial appendage  13  to form thrombus  30  and more importantly no thrombus  30  formed can leave the left atrial appendage  13  to cause heart attacks, strokes or ischemia. 
     The membrane  40  placed over the ostium  20  should be antithrombotic. In order to make the membrane antithrombotic, heparin or other anticoagulants or antiplatelet agent may be used on the membrane  40 . 
     When porous membranes  40  are used which have an ingrowth of cells, covering the membrane with endothelial cells, the endothelial cells present a smooth cellular wall covering the membrane which prevents thrombosis from occurring at the membrane. 
     When blood pools in the left atrial appendage  13 , thrombus  30  (blood dot) can accumulate therein, build upon themselves, and propagate out from the left atrial appendage  13  into the left atrium  11  entering the blood stream, leaving the heart and can block blood flow to the heart, brain, other organs, or peripheral vessels if it becomes lodged in the arteries thereof. 
     FIGS. 1 and 2 show a cross section of a human heart showing a thrombus  30  in the left atrial appendage  13 . The figures also show the atrial appendage ostium  20  which is to have a membrane  40  placed over it to prevent the thrombus  30  from escaping out of the atrial appendage  13  into the left atrium  11  and thus into the blood stream, which could cause a stroke, a heart attack or ischemia. The membrane  40  also prevents blood from entering the left atrial appendage  13  where it could pool due to poor circulation and become a thrombus. 
     FIG. 3 shows a cross section of a human heart showing a thrombus  30  in the right atrial appendage  23 . The right atrial appendage  23  can be treated in the same manner as the left atrial appendage  13 . 
     FIG. 4 shows a cross section of the left atrium  11 , the ostium  20  and the left atrial appendage  13  having a thrombus  30  therein. 
     FIG. 5 shows a first embodiment of the invention wherein the porous membrane  40  has a plurality of flexible prongs  50  which may be made from a shape memory alloy, such as Nitinol®, for retaining a predisposed shape. The prongs  50  may be atraumatic so that they do not perforate the left atrial appendage  13 . The prongs  50  may have atraumatic bulbs  55  on their tips so that the tips of the prongs  50  will not perforate the left atrial appendage  13 . Nitinol® has the property of being able to be placed in a catheter in a compact configuration and then expanded when released from the catheter to a predetermined memory shape. The shape selected may be for the prongs  50  to curve around the lip of the ostium  20  and then hug the sides of the left atrial appendage  13 . In this manner the membrane  40  will securely block the ostium  20  preventing blood from entering and particularly for preventing thrombosis  30  from leaving the left atrial appendage  13 . 
     The membrane  40  is self centering over the ostium  20  of the left atrial appendage  13 , by placing the prongs  50  in a circle around the membrane  40  such that the prongs  50  fit against the wall of the left atrial appendage  13  of or within the lumen of the ostium  20  to center the membrane  40  over the ostium  20 . The membrane  40  may also be centered by a centering rim  65  (see FIG. 6) attached to the back (appendage) side of the membrane  40  that protrudes into the ostium  20  for centering. The centering rim  65  has a diameter of less than the diameter of the membrane  40 . The centering means may also consist of a series of centering cables  66  (see FIG. 11) which attach to a spring  90  or tether  85  form the centering rim  65  or the membrane  40 , to assure that centering occurs with placement 
     Optionally electronics, such as sensors  300  and chips  310 , built into the membrane may be used to provide data about hemodynamics pressure, flow rates, temperature, heart rates, and electrical signals in the heart. When the membrane is placed in the left atrial appendage  13  the sensors  300  may measure pressures in the atria or atrial appendage. The sensors may also measure ventricular end diastolic pressures through the open mitral or cuspid valves. Other information about the heart may be gathered such as noise from accelerometers to detect leakage, valve efficiency, activity levels of the patient and other noise related data. The sensors  300  may also be blood oxygen sensors. The chip  310  may use telemetry to transmit the information gathered by the sensors  300  and processed or stored by the chip  310  to receiving devices to aid in the treatment of the patient. 
     In FIG. 6 the protective bulbs  55  are removed from the flexible prongs  50  of FIG. 5 such that flexible prongs  50  puncture the walls of the left atrial appendage  13  and secure the membrane  40  in place. The flexible prongs  50  may penetrate into the atrial appendage wall or extend through the atrial appendage wall. The prongs may have barbed ends  51  to prevent the prongs from withdrawing from the trial appendage wall. 
     The membrane  40  has centering rim  65  attached for centering the membrane in the ostium  20  and marker  320  in the membrane  40  for observing the position of the membrane while it is being inserted. The marker may be used for x-ray or ultrasound observation, 
     Although Nitinol® was cited above as a type of shape memory alloy prong material which can be used, any type of memory alloy may be used. Such alloys tend to have a temperature-induced phase change which will cause the material to have a preferred configuration when heated above a certain transition temperature. Other metals which may be used as prongs include corrosion resistant spring metals such as Elgiloy® or spring tempered steel. 
     Another embodiment of the invention is shown in FIG.  7 . It is similar to the embodiment shown in FIG.  5 . The embodiment in FIG. 7 has a stent  60  attached to the membrane  40  for expanding in the ostium  20  helping to secure the membrane  40  thereto. The prongs  50  operate in the same manner as in FIG. 5 hugging the inner walls of the left atrial membrane  13  to secure the membrane  40  to cover the ostium  20 . The stent  60  may also be made from Nitinol®, Elgiloy® or another expandable spring loaded or balloon expandable material. 
     The membrane  40  may be self centering over the ostium  20  of the left  13  atrial appendage, by placing the stent  60  into the ostium wherein the stent plugs the ostium with the membrane  40  centered in the stent. Further the prongs  50  fit against the wall of the left atrial appendage  13  of or within the lumen of the ostium  20  to center the membrane  40  over the ostium  20 . 
     In FIG. 8 the protective bulbs  55  are removed from the flexible prongs  50  of FIG. 7 such that flexible prongs  50  puncture the walls of the left atrial appendage  13  and secure the membrane  40  in place. The flexible prongs  50  may penetrate into the atrial appendage wall or extend through the atrial appendage wall. The prongs may have barbed ends  51  to prevent the prongs from withdrawing from the atrial appendage wall. 
     In the embodiment shown in FIG. 9 a larger expandable stent  70  is used to both engage the sides of the ostium  20  and hug the inside walls of the left atrial membrane  13 . Again the stent may be made of Nitinol®, Elgiloy® or other material which may be delivered in a catheter and expanded to the proper size and shape to securely hold the membrane  40  over the ostium  20  to prevent blood from entering the left atrial appendage  13  and for preventing thrombosis  30  from exiting. 
     FIG. 10 shows another embodiment of the invention wherein the membrane  40  is secured over the ostium  20  by means of an anchor  80  which is driven into or through the wall of the left atrial appendage  13  and secured therein by the surface area of the anchor so that it will not pull out of or through the wall of the left atrial appendage  13  or cause embolism from the left atrial appendage  13 . A tether  85  is attached to the anchor  80  and to the membrane  40  to secure the membrane  40  snuggly against the ostium  20 . A substance  270  such as thrombin, activated fibrinogen, or other biologic filler may be placed in the left atrial appendage  13  by injection through a catheter after the membrane  40  is in place such that blood is clotted in the atrial appendage so that it can not escape. The device delivery catheter itself may have a port for this injection. The port may also be used to inject contrast such as echocardiographic contrast that can be immediately visualized, and examined to determine whether there is a good seal between the ostium of the appendage and the device. The substance  270  injected into the atrial appendage may also be a sealant or filler to seal the membrane against leakage from the atrial appendage. The sealant material, filler material or blood clotting material may be used with any of the embodiments of the invention. 
     In another embodiment the catheter may inject a chemical ablation agent such as ethanol to ablate the myocardial cells in the sealed off atrial appendage  13  and thus limit atrial fibrillation by limiting or eliminating electrical propagation in the atrial appendage. 
     FIG. 11 shows another embodiment of the invention wherein membrane  40  has a spiral spring  90  in addition to the anchor  80 . The spiral spring  90  can be used in conjunction with or separately from the tether  85  to pull the membrane  40  against the ostium  20 . Although a spiral spring  90  has been shown in FIG. 11 the shape used may be oval, cylindrical, oblong, or other shape to connect the anchor  80  to the membrane  40 . In another embodiment shown in FIG. 12 the spiral spring  90  may fill the volume of the left atrial appendage  13  securing the membrane  40  to the ostium  20 . The spiral spring  90  filling the left atrial appendage  13  may also have an anchor  80  and tether  85  to help secure the membrane  40  to the ostium  20 . Alternatively centering rim  65  may be used as shown in FIG. 11 to center the membrane  40  over ostium  20  of left atrial appendage  13 . Centering cables  66  connected to spring  90  and either membrane  40  or centering rim  65  may also be used to center the membrane  40  over the ostium  20 . 
     FIG.13 shows yet another means of securing the membrane  40  over the ostium  20 . In this embodiment membrane  40  is directly attached to the ostium  20  by an adhesive  100 . 
     FIG. 14 shows a delivery catheter  125  containing a collapsed porous membrane  40  and a collapsed disk  130  connected to the porous membrane  40  by a spring  90  on catheter  21 . The disk  130  may be made of a flexible woven metal or a flexible woven metal with a thin porous polymer sandwiched inside. Disk  130  may also be a polymer weave. The disk  130  is flexible and compresses or folds so it fits into the delivery catheter  125  and expands to its desired shape after release from the delivery catheter  125 . Similarly membrane  40  compresses or folds to fit into the delivery catheter  125  and expands to its desired shape after release. FIG. 15 shows the porous membrane  40 , disk  130  and spring  90  from FIG. 14 in an expanded configuration outside of the delivery catheter  125 . 
     FIG. 15 shows the spring  90  connecting the porous membrane  40  and the disk  130  for urging them together. In other embodiments an elastic tether or a tether with teeth and a pawl on the porous membrane  40  to form a ratchet can also be used to pull the porous membrane  40  and the disk  130  together. 
     FIG. 16 shows the device of FIG. 15 applied to the left atrial appendage  13  having thrombus  30 . After the device is applied the spring  90 , pulls the disk  130  toward the porous membrane  40  collapsing the left atrial appendage  13  and trapping the thrombus  30  therein as shown in FIG.  17 . 
     FIG. 18 shows an alternate embodiment of the device in FIGS. 16 and 17 wherein the catheter  21  is equipped with a vacuum  140  for sucking out blood and thrombosis  30  found in the left atrial appendage  13 . The vacuum  140  will help collapse the left atrial appendage  13  such that spring  90  need not be as large as in FIG.  16 . 
     FIG. 19 shows an alternative embodiment of the device where the membrane  150  is inserted into the left atrial appendage  13  and fills it securing the membrane  150  therein. The membrane  150  may be delivered in a catheter as a compressed material and expanded in the atrial appendage  13  or be delivered in a liquid form which will fill the atrial appendage and be transformed into a membrane by curing with another chemical delivered by the catheter or with the aid of a UV light supplied through a fiber optic cable in the catheter  21 . By filling the left atrial appendage  13  with a membrane material  150  no blood can enter to pool and become a thrombus  30  and no thrombus  30  can exit to cause heart attacks, strokes and ischemia. 
     FIGS. 20-22 show another embodiment of the invention using an umbrella principle for securing the membrane  40  against the ostium  20 . FIG. 20 shows closed umbrella struts  160  entering the ostium  20  of left atrial appendage  13 . The membrane  40  is some distance back from the umbrella struts  160  at the bottom of the range of teeth  195  on pole  170 . FIG. 21 shows the umbrella struts inside of the left atrial appendage  13  with the struts  160  open. Umbrella opening structure  175  on pole  170  pushes the struts out to the umbrella open position. The umbrella opening structure  175  can be pushed to the open position or have a spring-loaded mechanism to push the struts  160  to the open position. The ends of the umbrella struts  160  engage the left atrial appendage wall around the ostium  20  and prevent the umbrella from being withdrawn from the left atrial appendage  13 . The ends of the umbrella struts  160  that engage the atrial appendage wall may be blunted or have bulbs on the tips or have padding so as not to puncture the left atrial appendage  13 . FIG. 22 shows the membrane  40  drawn up against the ostium  20  by ratcheting the membrane along pole  170 . The pawl mechanism  200  engages teeth  195  on pole  170  and is moved forward to snuggly block the ostium  20  with the membrane  40 . 
     FIG. 23 shows a stent  260  applied to the ostium  20  of left atrial appendage  13 . The stent  260  expands after leaving a delivery catheter such that the wall of the stent secures the stent by pressure to the ostium  20 . Membrane  240  folds or is compressed into the delivery catheter and expands as the stent  260  expands and lodges in the ostium  20  of the left atrial appendage  13 . 
     FIG. 24 shows the left atrial appendage  13  compressed such that the volume of the atrial appendage is reduced to almost nothing. With the volume reduced the atrial appendage will not have a large volume of blood which can produce a thrombus. In the embodiment shown disk  130  and spring  90  pull the left atrial appendage  13  toward membrane  40 . Although FIG. 24 shows the use of a disk  130  and spring  90  to act on the left appendage any method to reduce the volume of the atrial appendage as much as possible may be used. In addition to physically reducing the volume a substance  270  may be injected into the appendage to further limit its volume, or to clot the blood already present therein. 
     As shown in FIG. 24 the membrane  40  is much larger than the ostium  20 . The over-size membrane  40  may be used in all embodiments to ensure that the ostium  20  is completely blocked. 
     The devices described above may be percutaneously delivered to the left and right atrial appendages  13 ,  23  respectively. The devices may have material in them which enchance visualization or imaging by ultrasound, x-ray or other means making it easier for the device to be implanted and acutely centered over the ostium  20  of the atrial appendage  13 . This may consist of small beads placed strategically on the membrane, the connecting elements, or on the anchors. Referring to FIG. 1 catheter  21  is seen entering the heart by way of the aorta  12  to the left ventricle  16  passing through the mitral valve  17  and then entering the left atrial appendage  13  to apply the porous membrane  40  in one of the embodiments as disclosed above. In FIG. 2 the catheter  21  enters the heart from the femoral vein, passes through the inferior vena cava  18  to the right atrium and then passes through the fossa ovalis  19  or through the septum  29  into the left atrium  11  and then approaches the left atrial appendage  13  to apply the porous membrane  40  thereto. FIG. 3 shows the catheter  21  being applied to the right atrial appendage  23 . Catheter  21  may enter the heart through the jugular vein  28  or the femoral vein to the inferior vena cava  18 . 
     It should be understood that the invention may be practiced with numerous moans of attaching the membrane  40  to cover the ostium  20  of the atrial appendages  13  and  23 . Any combination of the attachment means with adhesives, prongs, stents, anchors, dish, tethers or springs may be used. The membrane may also be inside of the atrial appendages  13  and  23 , or may penetrate the atrial appendage and provide a means to securely lock the membrane device into place. Other means of providing a membrane for blocking blood flow into and blood clots out of the atrial appendages not listed may also be used. A substance may be injected into the appendage to limit its volume, or to clot the blood already present. 
     In all of the above embodiments the blood of the appendage may be facilitated to clot in order to form a large, immobile mass. Alternatively, the appendage may be filled with any substance that will occupy volume. Examples are fibrin, prosthetic polymers (PLLA), Silicone, or a balloon that is delivered and remains in place for long periods of time. 
     All of the above embodiments shown and discussed for the left atrial appendage  13  are also useable on the right atrial appendage  23 . Further the invention may be used to close fistulae or connections elsewhere in the body such as the colon or bronchopulmonary systems. The invention may also be used to seal false aneurysms. When the membrane is placed in a false aneurysm it will strengthen the defect and may help to avoid surgery. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims the invention may be practiced otherwise than as specifically described.