Patent Publication Number: US-8972003-B2

Title: Perivascular leak repair system

Description:
TECHNICAL FIELD 
     The technical field of this disclosure is medical devices, particularly, perivascular leak repair systems and method of using the same. 
     BACKGROUND OF THE INVENTION 
     Heart valves, such as the aortic valve, are sometimes damaged by disease or by aging, which can cause problems with the proper function of the valve. Heart valve problems generally take one of two forms: stenosis, in which a valve does not open completely or the opening is too small, resulting in restricted blood flow; or insufficiency, in which blood leaks backward across the valve that should be closed. Valve replacement may be required in severe cases to restore cardiac function. 
     Valve replacement can be performed through open-heart surgery, open chest surgery, or percutaneously. The native valve is removed and replaced with a prosthetic valve, or a prosthetic valve is placed over the native valve. The open chest and percutaneous procedures avoid opening the heart and cardiopulmonary bypass. Regardless of the procedure used, perivascular leakage can occur around the prosthetic valve and cannot be detected until the heart is closed and beating. 
       FIG. 1  shows a prosthetic aortic valve implanted in the aorta. Perivascular leakage, i.e., back flow from the ascending aorta  20  to the left ventricle  22  during diastole, will occur if the prosthetic aortic valve  24  is not sealed in the aorta, creating a perivascular leak  26 . Some perivascular leakage may heal shut over time, but the healing is uncertain and the leakage reduces valve function until the healing is complete. Currently, repair of perivascular leakage requires an open-heart surgery to repair the leak with additional sutures. Repair may also require replacement of the prosthetic valve if the prosthetic valve size is incorrect. Open-heart surgery involves risk, expense, and an extended recovery time. Open-heart surgery also requires cardiopulmonary bypass with risk of thrombosis, stroke, and myocardial infarction. 
     It would be desirable to have a perivascular leak repair system that would overcome the above disadvantages. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention provides a perivascular leak repair system that provides immediate perivascular leak repair. 
     Another aspect of the present invention provides a perivascular leak repair system that avoids open-heart surgery for perivascular leak repair. 
     Another aspect of the present invention provides a perivascular leak repair system that uses leakage flow to carry sealant into the perivascular leak. 
     Another aspect of the present invention provides a perivascular leak repair system that avoids injecting unnecessary sealant in the circulatory system. 
     The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention, rather than limiting the scope of the invention being defined by the appended claims and equivalents thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a prosthetic aortic valve implanted in the aorta. 
         FIG. 2  shows a perivascular leak repair system inserted percutaneously and made in accordance with the present invention. 
         FIG. 3  shows a perivascular leak repair system inserted through the aortic wall and made in accordance with the present invention. 
         FIGS. 4A &amp; 4B  show detailed and general block diagrams, respectively, of a perivascular leak repair system made in accordance with the present invention. 
         FIG. 5  shows a flow chart for a method of using a perivascular leak repair system made in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT 
       FIG. 2  shows a perivascular leak repair system inserted percutaneously. A repair catheter is advanced percutaneously to the perivascular leak and sealant injected at the perivascular leak. The sealant injection can be coordinated with the heartbeat to sweep the sealant into the perivascular leak. 
     In the example shown, the repair catheter  40  can be inserted inguinally into the femoral artery and advanced until the distal tip  42  is near the perivascular leak  44  at the prosthetic aortic valve  48 . The location of the perivascular leak  44  can be determined using echocardiography before inserting the repair catheter  40 . The location of the distal tip  42  relative to the perivascular leak  44  can be determined by an imaging or navigation system. In one embodiment, the distal tip  42  can have a radiopaque marker  46  and fluoroscopy can be used to locate the distal tip  42 . In another embodiment, a non-fluoroscopic navigation system, such as the Localisa® intracardiac navigation system from Medtronic, Inc., of Minneapolis, Minn., can be used to locate the distal tip  42 . The Localisa® intracardiac navigation system uses three skin electrode pairs, positioned in x,y,z directions around the heart to track catheters. In yet another embodiment, fluoroscopy can be used in conjunction with a non-fluoroscopic navigation system to locate the distal tip  42 . 
     The repair catheter  40  can be any catheter that can locate a distal tip  42  near the perivascular leak  44  and includes a lumen  50  to inject a sealant. In one embodiment, the repair catheter  40  can be steerable, such as the MyoCath™ catheter from Bioheart, Inc., MyoStar catheter from Johnson &amp; Johnson, Inc., or the Stiletto catheter from Boston Scientific, Inc. In another embodiment, the distal tip  42  can have retractable needle or corkscrew elements to connect the distal tip  42  with the cardiac tissue at the perivascular leak  44 . 
     When the distal tip  42  is at or near the perivascular leak  44 , a sealant can be injected through a lumen  50  in the repair catheter  40  to seal the perivascular leak  44 . The sealant can be any non-toxic sealant that can flow into or cover over the perivascular leak  44 . The sealant can flow into and adhere to the walls of the perivascular leak  44 . The sealant can degrade with time with tissue ingrowth maintaining the seal. 
     The sealant can use the body&#39;s own clotting and repair mechanisms to stop the perivascular leak. In one embodiment, the sealant can be fibrin glue. Fibrin glues are typically made by contacting a solution or suspension of the blood protein fibrinogen with an enzyme or other reagent which can crosslink it. Typically, the enzyme thrombin is used, which cleaves the fibrinogen molecule, forming fibrin monomer which then spontaneously polymerizes. This is a natural reaction involved in the formation of blood clots. Fibrinogen can be obtained from the patient or from pooled homologous human blood. The blood protein fibrinogen and enzyme thrombin can be injected through separate lumens in the repair catheter so that the two components meet and mix at the perivascular leak. In another embodiment, the sealant can be collagen paste. Collagen paste is typically collagenous material ground to a fine powder and mixed with water or aqueous saline solution until injectable. The collagen paste is thrombogenic, so that it will form clots and recruit fibrin in the perivascular leak. 
     Other sealants which can be used to seal the perivascular leak include, but are not limited to, activated platelet gel, hydrogels, N-butyl cyanoacrylate, isobutyl-2 cyanoacrylate, alykyl cyanoacrylate, silicone rubber, Ethibloc amino acid gel, autologous material such as fat dura, EVAL ethylene vinyl alcohol copolymer, EMBOLYX ethylene vinyl alcohol copolymer, poly-vinyl alcohol, alginates such as polysachrides, posphoryl choline-hydrogel, activated microparticles, combinations thereof, and the like. 
     The repair catheter  40  can also have a pressure sensor  52  for sensing pressure in the ascending aorta  58 . The pressure sensor  52  can transmit a pressure signal to the heart phase detector, which can use the pressure signal to determine when the heart is in diastole. Sealant injected during diastole will follow the backflow from the ascending aorta  58  into the perivascular leak  44  to provide a superior seal without releasing substantial sealant into the circulatory system. In one embodiment, the repair catheter  40  can include a pressure lumen exiting near the distal tip  42  to transmit the pressure in the ascending aorta  58  to a pressure sensor mounted external to the patient or mounted proximally the distal tip  42  within the repair catheter  40  itself. In yet another embodiment, the pressure sensor can be omitted and an electrocardiogram (ECG) used to determine diastole. In yet another embodiment, the repair catheter  40  can include a Doppler echo probe for detecting flow and determining diastole. The Doppler echo probe can also be used for imaging the perivascular leak, the prosthetic valve, and the surrounding structure. The Doppler echo probe can also be used to detect emboli. 
     A filter  54  can be disposed on the repair catheter  40  across the ascending aorta  58  before the brachiocephalic artery to catch and retain sealant or other emboli discharged during the perivascular leak repair procedure. In another embodiment, a separate filtering device, such as the Scion Cardio-Vascular SCI-PRO® guide wire based retrieval device from Scion Cardio-Vascular, Inc., of Miami, Fla., can be inserted in parallel with the repair catheter  40  to remove embolic material during the perivascular leak repair. 
       FIG. 3 , in which like elements share like reference numbers with  FIG. 2 , shows a perivascular leak repair system inserted through the aortic wall. Accessing the perivascular leak  44  through the aortic wall avoids opening the heart itself and is possible when the chest is open. This approach is particularly advantageous if a perivascular leak is discovered after open chest valve replacement surgery, but before the chest is closed. A repair catheter  40  is placed through the aortic wall and sealant injected at the perivascular leak  44  from the lumen  50 . The sealant injection can be coordinated with the heartbeat to sweep the sealant into the perivascular leak. 
       FIGS. 4A &amp; 4B  show detailed and general block diagrams, respectively, of a perivascular leak repair system. The control system coordinates sealant injection with the heartbeat to sweep the sealant into the perivascular leak. 
       FIG. 4A  shows one embodiment of perivascular leak repair system. The perivascular leak repair system  80  comprises a syringe  82  providing sealant to a repair catheter  84  through a flow control valve  86 . The flow control valve  86  is responsive to a flow control signal  88  from a flow controller  90  to stop or allow sealant flow from the syringe  82  to the repair catheter  84 . The flow controller  90  is responsive to a diastole phase signal  92  from the heart phase detector  94 . 
     In use, the repair catheter  84  is advanced so that the distal tip is near the perivascular leak. The syringe  82  and flow control valve  86  remain outside the patient. The heart phase detector  94  monitors heartbeat using pressure at the distal tip of the repair catheter  84  or an electrocardiogram (ECG). When the heart phase detector  94  detects the heart is in diastole, the heart phase detector  94  sends a diastole phase signal  92  to the flow controller  90  indicating the same. The flow controller  90 , in turn, sends a flow control signal  88  to the flow control valve  86  directing the flow control valve  86  to permit flow. If the surgeon is applying pressure to the syringe  82 , sealant will flow through the flow control valve  86  and the repair catheter  84  to enter the perivascular leak with the backflow through the perivascular leak. During systole, the flow control valve  86  is closed and no flow is permitted through the repair catheter  84 . Applying sealant during diastole, and not during systole, gets the sealant into the periascular leak where required and avoids excess sealant being carried into the circulatory system. 
       FIG. 4B  shows another embodiment of perivascular leak repair system. The perivascular leak repair system  100  comprises a sealant reservoir  102  providing sealant to a repair catheter  104  through a flow control device  106 . The flow control device  106  is responsive to a flow control signal  108  from a flow controller  110  to stop or allow sealant flow from the sealant reservoir  102  to the repair catheter  104 . The flow controller  110  is responsive to a diastole phase signal  112  from the heart phase detector  114  and an injection signal  120  from the injection switch  122 . The flow controller  110  can also be responsive to an injection amount signal  116  from the injection amount selector  118 . 
     The sealant reservoir  102  and flow control device  106  are selected to provide sealant flow to the repair catheter  104 . In one embodiment, the sealant reservoir  102  can be pressurized and the flow control device  106  can be a valve. In another embodiment, the flow control device  106  can be a pump. Separate sealant reservoirs and flow paths can be provided for multi-part sealants that activate on mixing. 
     In use, the repair catheter  104  is advanced so that the distal tip is near the perivascular leak. The sealant reservoir  102  and flow control device  106  remain outside the patient. The heart phase detector  114  monitors heartbeat using pressure at the distal tip of the repair catheter  104 , an electrocardiogram (ECG), or a Doppler echo probe. When heart phase detector  114  detects the heart is in diastole, the heart phase detector  114  sends a diastole phase signal  112  to the flow controller  110  indicating the same. When the injection switch  122  is activated by the surgeon providing an injection signal  120  to the flow controller  110 , and the heart phase detector  94  detects the heart is in diastole providing a diastole phase signal  92 , the flow controller  110  sends a flow control signal  108  to the flow control device  106  directing the flow control device  106  to permit flow. Sealant will flow through the flow control device  106  and the repair catheter  104  to enter the perivascular leak with the backflow through the perivascular leak each time the heart is in diastole until the surgeon releases the injection switch  122 . Flow is stopped each time the heart is isystole, even though the surgeon maintains the injection switch  122  in the inject position. The flow controller  110  can also be responsive to an injection amount signal  116  from the injection amount selector  118  to limit to a predetermined amount the amount of sealant injected each time the heart is in diastole or to limit the amount of sealant injected each time the surgeon pushes the injection switch  122 . 
     Emboli detection can be provided to detect emboli that might occur from or during the procedure. In one embodiment, the emboli detector can be a Doppler echo probe disposed on the repair catheter  104 . In another embodiment, the emboli detector can be external, such as transcranial Doppler (TCD) ultrasound or the like. 
       FIG. 5  shows a flow chart for a method of using a perivascular leak repair system. A perivascular leak is identified at  140 . A repair catheter is inserted to the perivascular leak  14  and sealant injected at the leak  144 . The repair catheter is removed at  146 . Typically, the sealant can be fibrin glue, collagen paste, activated platelet gel, or the like. 
     Identifying the perivascular leak  140  can comprise identifying the perivascular leak by echocardiography. While the repair catheter is inserted to the perivascular leak  142 , the repair catheter can be located by an imaging or navigation system, such as fluoroscopy or a Localisa® non-fluoroscopic intracardiac navigation system from Medtronic, Inc. Injecting sealant at the perivascular leak  144  can comprise monitoring heart phase for diastole and injecting sealant at the perivascular leak during the diastole, and further comprise not injecting sealant during systole. The method can further comprise checking whether the perivascular leak is sealed and injecting sealant at the perivascular leak if the perivascular leak is not sealed. This can be repeated until the perivascular leak is sealed. 
     It is important to note that  FIGS. 1-3 ,  4 A,  4 B, and  5  illustrate specific applications and embodiments of the present invention, and is not intended to limit the scope of the present disclosure or claims to that which is presented therein. For example, the perivascular leak repair system of the present invention can be used for other heart valves in addition to the aortic valve. Different arterial and venous approaches to the perivascular leak can also be used. Upon reading the specification and reviewing the drawings hereof, it will became immediately obvious to those skilled in the art that myriad other embodiments of the present invention are possible, and that such embodiments are contemplated and fall within the scope of the presently claimed invention. 
     While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.