Patent Publication Number: US-2021169641-A1

Title: Percutaneuous temporary aortic valve

Description:
CROSS-REFERENCE 
     This application is a continuation of U.S. patent application Ser. No. 15/821,056, filed Nov. 22, 2017, now U.S. Patent No. , ; which is a continuation of U.S. patent application Ser. No. 15/083,768, filed Mar. 29, 2016, now U.S. Pat. No. 9,855,143; which claims the benefit of U.S. Provisional Patent Application No. 62/140,111, filed Mar. 30, 2015; the full contents of which are incorporated herein by reference. 
     The subject matter of this application is related to the subject matter of the following co-assigned patents and pending patent applications: U.S. patent application Ser. No. 11/781,924 (filed on Jul. 23, 2007 and issued on Mar. 4, 2014 as U.S. Pat. No. 8,663,318), Ser. No. 12/180,223 (filed on Jul. 25, 2008 and issued on Mar. 4, 2014 as U.S. Pat. No. 8,663,319), Ser. No. 13/227,276 (filed on Sep. 7, 2011), Ser. No. 14/154,890 (filed on Jan. 14, 2014), and Ser. No. 14/155,060 (filed on Jan. 14, 2014), the full contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to medical devices, systems, and methods. In particular, the present disclosure relates to the percutaneous delivery and deployment of a temporary aortic valve to facilitate other percutaneous procedures such as the delivery of aortic replacement valves or to serve as a standalone hemodynamic support device when the native aortic valve is damaged from infective endocarditis or trauma, for example. The native aortic valve damage may also be iatrogenic from deliberate valve resection prior to valve placement. 
     The native aortic valve can fail acutely from infection or mechanical trauma. In endocarditis of the aortic valve, the timing for surgery may be limited during the active phase of the infection. The condition can be fatal as significant acute aortic regurgitation may cause decompensating heart failure. Mechanical failure of the aortic valve can occur from proximal aortic dissection or direct leaflet and/or annular tear with similar potential lethal outcome. Patients suffering from significant aortic valve disease are frequently treated by aortic valve replacement procedures. While most aortic valve replacements are still performed in open chest procedures, recently there have been significant advances in minimally invasive aortic valve replacement where the valve is introduced through a transapical approach (minimally invasive), a transaortic approach (minimally invasive), or a transvascular (percutaneous) approach over the aortic arch. In the era of transcatheter aortic valve intervention (TAVI), iatrogenic damage to the aortic valve may become relevant especially with suggestions for valve resection prior to replacement. The clinical needs for a percutaneous temporary aortic valve are therefore apparent. 
     Transapical, transaortic, and transfemoral percutaneous aortic valve procedures are “beating heart” procedures where continuing blood flow from the left ventricle into the aorta creates hemodynamic forces on the replacement valves and the tools used in the replacement procedures. In an effort to control the hemodynamic forces and to stabilize the tools and valve used for replacement, that the use of a “temporary aortic valve” (TAV) has recently been proposed. As described in commonly owned published U.S. Patent Publications Nos. US 2009/0030503, US 2009/0030510 and US 2012/0116439, the full disclosures of which are incorporated herein by reference, a catheter is intravascularly introduced over the aortic arch to position a balloon assembly in the ascending aorta just above the Sinus of Valsalva. The balloon assembly includes three equally sized balloons disposed in parallel about the distal tip of the catheter, and the inflated balloons together limit retrograde blood flow (flow in the direction from the aorta toward the aortic valve) during diastole, thus limiting disturbance of the tools and/or valves located in the aortic valve annulus during the procedure. The balloon inflation only partially occludes the aortic lumen in order to both allow antegrade flow during systole and to permit a limited retrograde flow during diastole in order to perfuse the coronary vasculature through the Sinus of Valsalva and to protect the left ventricle from excessive volume overload. As a standalone procedure, in cases of naturally occurring damage (as opposed to iatrogenic) of the native aortic valve such as from infective endocarditis or trauma, the temporary aortic valve can also be placed similarly in the ascending aorta as a hemodynamic support device. 
     While of great potential benefit, the use of the fixed-balloon structures described in the prior patent applications is necessarily a compromise between resistance to regurgitation during diastole and forward blood flow patency through the aorta during systole. Even when the balloons are collapsed to their minimum cross-sectional area in a counter-pulsating balloon system, the complex balloon structures may be cumbersome to advance through tortuous vasculature and may be prone to mechanical failure, particularly due to the relatively high number of mechanical elements and after repeated cycles of expansion and collapse. 
     Previous models of catheter-based temporary aortic valves for the treatment of acute aortic regurgitation have also not reached clinical relevance mostly due to their inability to adequately protect coronary circulation. When deployed in the ascending aorta, the compromised diastolic coronary flow from acute aortic regurgitation has been shown to further reduce from the occlusive nature of the device designs. Myocardial ischemia can occur in acute aortic regurgitation alone without concomitant coronary artery disease. Coronary flow obstruction by the temporary aortic valve should therefore be overcome in improved device designs. 
     For these reasons, it would be desirable to provide improved methods and systems for occluding the aorta to limit aortic regurgitation during valve repair and replacement procedures as well as to provide a standalone device for hemodynamic support in the native aortic valve when damaged by naturally occurring aortic regurgitation, such as from infective endocarditis or trauma. In at least the latter application, the methods and systems can be a life-saving bridge to open heart surgery to correct the aortic valve damage. 
     The following references may be of interest: 
     Aksoy S, Cam N, Guney MR, Gurkan U, Oz D, Poyraz E, Eksik A, Agirbasli M. Myocardial ischemia in severe aortic regurgitation despite angiographically normal coronary arteries.  Tohoku J Exp Med  2012;226(1):69-73. 
     Ardehali A, Segal J, Cheitlin M. Coronary blood flow reserve in acute aortic regurgitation.  J Am Coll Cardiol  1995;25:1387-1392. 
     Davies J E, Whinnett Z I, Francis D P, Manisty C H, Aguardo-Sierra J, Willson K, Foale R A, Malik I S, Hughes A D, Parker K H, Mayet J. Evidence of a dominant backward-propagating “suction” wave responsible for diastolic coronary filling in humans, attenuated in left ventricular hypertrophy.  Circulation  2006; 113 (14): 1768-78. 
     Ho PC. Percutaneous aortic valve replacement: a novel design of the delivery and deployment system.  Minim Invasive Ther Allied Technol  2008;17(3):190-194. 
     Ho PC. Percutaneous aortic valve replacement (part 2): An innovative approach to miniaturize the delivery system based on the novel temporary valve technology.  Minim Invasive Ther Allied Technol  2009; 18(3): 172-177. 
     Ho PC. Percutaneous aortic valve replacement (part 3): Counterpulsation temporary valve technology.  Minim Invasive Ther Allied Technol  2011;20(2):101-106. 
     Ho PC. Qualitative hemodynamic validation of a percutaneous temporary aortic valve; a proof of concept study.  J Med Eng Technol  2011;35(2):115-120. 
     Ho P C, Nguyen M E, Golden P J. Percutaneous temporary aortic valve: a proof-of-concept animal model.  J Heart Valve Dis  2013;22:460-467. 
     Moulopoulos S D, Anthopoulos L, Stamatelopoulos S, Stefadouros M, Catheter-mounted aortic valves.  Ann Thorac Surg  1971;11(5):423-430. 
     Moulopoulos S D, Anthopoulos L, Antonatos P G, Adamopoulos P N, Nanas J N. Intraaortic balloon pump for relief of aortic regurgitation.  J Thorac Cardiovasc Surg  1980;80:38-44. 
     Phillips S J, Ciborski M, Freed P S, Cascade P N, Jaron D. A temporary catheter-tip aortic valve: hemodynamic effects on experimental acute aortic insufficiency.  Ann Thorac Surg  1976 Feb;21(2):134-7. 
     Quaden R, Attmann T, Boening A, Cremer J, Lutter G. Percutaneous aortic valve replacement: Resection before impintation.  Eur J Cardiothorac Surg  2005;27:836-840. 
     Salizzoni S, Bajona P, Zehr K J, Anderson W D, Vandenberghe S, Speziali G. Transapical off-pump removal of the native aortic valve; a proof-of-concept animal study.  J Thorac Cardiovasc Surg  2009;138(2):468-473. 
     Wendt D, Muller W, Hauck F, Thielmann M, Wendt H, Kipfmüller B, Vogel B, Jakob H. In vitro results of a new minimally invasive aortic valve resecting tool.  Eur J Cardiothorac Surg  2009;35(4):622-627. 
     SUMMARY 
     The issues discussed above and others may be addressed by the devices, systems, and methods of the present disclosure. 
     A novel percutaneous transcatheter temporary aortic valve (TAV) is presented. The valve may include a cone-shaped membrane based occlusion element. In ventricular systole, the occlusion element may collapse to reduce aortic obstruction. In ventricular diastole, the occlusion element may expand to occlude the aorta to inhibit regurgitation while allowing coronary filling through a gap or opening in the occlusion element. The diastolic gap or opening may have a variety of sizes to balance adequate coronary flow with protection against acute regurgitation. In contrast with prior occlusive devices, there is typically no fixed gap size for the membrane based occlusion element in systole. By removing the systolic obstructive component of a fixed gap, the membrane based occlusion element&#39;s diastolic gap size can be smaller to provide better protection against acute regurgitation. A lower limit of the gap:aorta cross-sectional area ratio can be redefined based on adequate coronary flow. For example, based on experimental results and/or mathematical models, the size of the diastolic gap or opening may be selected to optimize coronary filing while protecting against aortic regurgitation. 
     Aspects of the present disclosure provide temporary aortic valve apparatuses which may comprise a catheter shaft and a flexible occluding membrane. The catheter shaft may be adapted to be advanced through a vasculature of a patient for placement within an aorta or other blood vessel of the patient. The flexible occluding membrane may have a lateral side coupled to the catheter shaft and may be adapted to alternate between an expanded occluding configuration and a collapsed lesser occluding configuration in the aorta or other blood vessel in synchrony with ventricular diastole and systole. 
     The flexible occluding membrane may be adapted to assume the expanded occluding configuration in response to blood flow in the aorta during ventricular diastole. The flexible occluding membrane may be adapted to assume the collapsed lesser occluding configuration in the aorta in response to blood flow therein during ventricular systole. 
     The flexible occluding membrane may have an opening to allow blood perfusion therethrough when in the expanded occluding configuration. The opening may be positioned at substantially a center of the flexible occluding membrane. The opening and the center of the flexible occluding membrane may be disposed at a distal tip of the flexible occluding membrane. Alternatively or in combination, the opening may be positioned at a location offset from a center of the flexible occluding membrane. The flexible occluding membrane may have a plurality of openings to allow blood perfusion therethrough when in the expanded occluding configuration. The opening(s) may have a variety of cross sectional sizes. For example, the opening(s) may have a cross-sectional size of 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less, to name of few sizes, of the aorta or other blood vessel. 
     The catheter shaft may further comprise a distal anchoring loop. The distal anchoring loop may have an expanded, curved configuration and a collapsed, straightened configuration. In the expanded, curved configuration, the distal anchoring loop may anchor the catheter shaft and the flexible occluding membrane in the aorta or other blood vessel. For example, the distal anchoring loop may be sized to appose and/or exert a radially outward force on the inner wall of the aorta or other blood vessel when in the expanded, curved configuration, thereby anchoring the catheter shaft and the flexible occluding membrane in place. In the collapsed, straightened configuration, the distal anchoring loop may be in a smaller cross-section configuration to facilitate the advancement and removal of the catheter shaft and the flexible occluding membrane. 
     The flexible occluding membrane may have a conical shape. The conically-shaped flexible occluding membrane may comprise an annular proximal lip adapted to appose an inner wall of the aorta when the flexible occluding membrane is in the expanded occluding configuration. The conical shape of the flexible occluding membrane may be oriented with the larger opening (proximal lip) away from the aortic valve. The flexible occluding membrane may be adapted to be positioned within an ascending aorta of the patient to provide occlusion therein. The flexible occluding membrane may be adapted to be positioned within the ascending aorta just above the Sinus of Valsalva and coronary ostia. For example, the diameter of the annular proximal lip may be selected to closely match or exceed that of a typical human ascending aorta above the Sinus of Valsalva and coronary ostia. 
     Aspects of the present disclosure also provide temporary aortic valve apparatuses comprising a catheter shaft and a flexible occluding membrane having an opening to allow blood perfusion therethrough when the membrane is in an expanded configuration. The catheter shaft may be adapted to be advanced through a vasculature of a patient for placement within an aorta or other blood vessel of the patient. The flexible occluding membrane may be coupled to the catheter shaft and adapted to alternate between an expanded occluding configuration and a collapsed lesser occluding configuration in the aorta in synchrony with ventricular diastole and systole. 
     The catheter shaft and the flexible occluding membrane may be coupled to one another at a center of the flexible occluding membrane or at a location offset from a center of the flexible occluding membrane. 
     The flexible occluding membrane may be adapted to assume the expanded occluding configuration in response to blood flow in the aorta during ventricular diastole. The flexible occluding membrane may be adapted to assume the collapsed lesser occluding configuration in the aorta in response to blood flow therein during ventricular systole. 
     The opening may be positioned at substantially a center of the flexible occluding membrane. The opening and the center of the flexible occluding membrane may be disposed at a distal tip of the flexible occluding membrane. The opening may be positioned at a location offset from a center of the flexible occluding membrane. The flexible occluding membrane may have a plurality of openings to allow blood perfusion therethrough when in the expanded occluding configuration. The opening(s) may have a variety of cross sectional sizes. For example, the opening(s) may have a cross-sectional size of 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less, to name of few sizes, of the aorta or other blood vessel. 
     The catheter shaft may comprise a distal anchoring loop. The distal anchoring loop may have an expanded, curved configuration and a collapsed, straightened configuration. In the expanded, curved configuration, the distal anchoring loop may anchor the catheter shaft and the flexible occluding membrane in the aorta or other blood vessel. For example, the distal anchoring loop may be sized to appose and/or exert a radially outward force on the inner wall of the aorta or other blood vessel when in the expanded, curved configuration, thereby anchoring the catheter shaft and the flexible occluding membrane in place. In the collapsed, straightened configuration, the distal anchoring loop may be in a smaller cross-section configuration to facilitate the advancement of the catheter shaft and the flexible occluding membrane. 
     The flexible occluding membrane may have a conical shape. The conically-shaped flexible occluding membrane may comprise an annular proximal lip adapted to appose an inner wall of the aorta when the flexible occluding membrane is in the expanded occluding configuration. The flexible occluding membrane may be adapted to be positioned within an ascending aorta of the patient to provide occlusion therein. The flexible occluding membrane may be adapted to be positioned within the ascending aorta just above the Sinus of Valsalva and coronary ostia. For example, the diameter of the annular proximal lip may be selected to closely match or exceed that of a typical human ascending aorta just above the Sinus of Valsalva and coronary ostia. 
     Aspects of the present disclosure may also provide methods for regulating aortic regurgitation during an aortic valve diagnostic or treatment procedure. A catheter shaft may be advanced through a vasculature of a patient so that a flexible occluding membrane having a lateral side coupled to the catheter shaft is positioned within an aorta or other blood vessel of the patient. Blood flow in the aorta may cause the flexible occluding membrane to alternate between an expanded occluding configuration and a collapsed lesser occluding configuration in synchrony with ventricular diastole and systole. Blood flow in the aorta during ventricular diastole may cause the flexible occluding membrane to assume the expanded occluding position. The flexible occluding membrane may passively alternate between the configurations due to the blood flow, thereby obviating the need for any active, mechanical actuation of device and reducing risks of mechanical failure of the device. Expansion of the flexible occluding member during ventricular diastole may inhibit aortic regurgitation. 
     In advancing the catheter shaft, the flexible occluding membrane may be positioned within the ascending aorta above the Sinus of Valsalva and coronary ostia. Expansion of the flexible occluding member during ventricular diastole may inhibit aortic regurgitation while allowing perfusion of the coronary arteries via the Sinus of Valsalva. Perfusion of the coronary arteries via the Sinus of Valsalva may be allowed by an opening on the flexible occluding membrane. The opening may be positioned at a variety of locations. There may be more than one opening. The opening may be positioned at substantially a center of the flexible occluding membrane. The opening and the center of the flexible occluding membrane may be disposed at a distal tip of the flexible occluding membrane. The opening may be positioned at a location offset from a center of the flexible occluding membrane. Perfusion of the coronary arteries via the Sinus of Valsalva may be allowed by a plurality of openings on the flexible occluding membrane. The opening(s) may have a variety of cross sectional sizes. For example, the opening(s) may have a cross-sectional size of 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less, to name of few, of the aorta or other blood vessel. 
     A distal anchoring loop of the catheter shaft may be expanded to a curved configuration to anchor the catheter shaft and the flexible occluding membrane in the aorta or other blood vessel. For example, the distal anchoring loop may be expanded to a size in which it apposes and/or exerts a radially outward force on the inner wall of the aorta or other blood vessel, thereby anchoring the catheter shaft and the flexible occluding membrane in place. The distal anchoring loop may have an expanded, curved configuration and a collapsed, straightened configuration. To advance or retract the distal anchoring loop, it may be collapsed and/or straightened to a lower cross-sectional area configuration. 
     The flexible occluding membrane may have a conical shape and an annular proximal lip. Blood flow in the aorta during diastole may cause the annular proximal lip to appose an inner wall of the aorta. Blood flow in the aorta during ventricular systole may cause the flexible occluding membrane to assume the collapsed lesser occluding configuration. Collapse of the flexible occluding membrane during ventricular systole may lessen inhibition of blood flow from a left ventricle of the patient to the aorta. 
     An aortic valve replacement or repair procedure may be performed while blood flow in the aorta continues to cause the flexible occluding membrane to alternate between the expanded occluding configuration and the collapsed lesser occluding configuration in synchrony with diastole and systole. An example of such a procedure may include the advancement of a replacement valve through a lumen of the catheter shaft. 
     The catheter shaft may be advanced over an aortic arch of the patient. The catheter shaft may be advanced or introduced to the aorta or other blood vessel transapically, transaortically, or transfemorally, to name a few approaches. 
     Aspects of the present disclosure may also provide methods for regulating aortic regurgitation during an aortic valve diagnostic or treatment procedure. A catheter shaft may be advanced through a vasculature of a patient so that a flexible occluding membrane coupled to the catheter shaft is positioned within an aorta or other blood vessel of the patient. Blood flow in the aorta may cause the flexible occluding membrane to alternate between an expanded occluding configuration and a collapsed lesser occluding configuration in synchrony with ventricular diastole and systole. Perfusion of the coronary arteries via the Sinus of Valsalva may be allowed by an opening on the flexible occluding membrane. Blood flow in the aorta or other blood vessel during ventricular diastole may cause the flexible occluding membrane to assume the expanded occluding position. The flexible occluding membrane may passively alternate between the configurations due to the blood flow, thereby obviating the need for any active, mechanical actuation of device and reducing risks of mechanical failure of the device. Expansion of the flexible occluding member during ventricular diastole may inhibit aortic regurgitation. 
     The opening may be positioned at a variety of locations. There may be more than one opening. The opening may be positioned at substantially a center of the flexible occluding membrane. The opening and the center of the flexible occluding membrane may be disposed at a distal tip of the flexible occluding membrane. The opening may be positioned at a location offset from a center of the flexible occluding membrane. Perfusion of the coronary arteries via the Sinus of Valsalva may be allowed by a plurality of openings on the flexible occluding membrane. The opening(s) may have a variety of cross sectional sizes. For example, the opening(s) may have a cross-sectional size of 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less, to name of few, of the aorta or other blood vessel. 
     A distal anchoring loop of the catheter shaft may be expanded to a curved configuration to anchor the catheter shaft and the flexible occluding membrane in the aorta or other blood vessel. For example, the distal anchoring loop may be expanded to a size in which it apposes and/or exerts a radially outward force on the inner wall of the aorta or other blood vessel, thereby anchoring the catheter shaft and the flexible occluding membrane in place. The distal anchoring loop may have an expanded, curved configuration and a collapsed, straightened configuration. To advance or retract the distal anchoring loop, it may be collapsed and/or straightened to a lower cross-sectional area configuration. 
     In advancing the catheter shaft, the flexible occluding membrane may be positioned within the ascending aorta above the Sinus of Valsalva and coronary ostia. Expansion of the flexible occluding member during ventricular diastole may inhibit aortic regurgitation while allowing perfusion of the coronary arteries via the Sinus of Valsalva. 
     The flexible occluding membrane may have a conical shape and an annular proximal lip. Blood flow in the aorta during diastole may cause the annular proximal lip to appose an inner wall of the aorta. Blood flow in the aorta during ventricular systole may cause the flexible occluding membrane to assume the collapsed lesser occluding configuration. Collapse of the flexible occluding membrane during ventricular systole may lessen inhibition of blood flow from a left ventricle of the patient to the aorta. 
     An aortic valve replacement or repair procedure may be performed while blood flow in the aorta continues to cause the flexible occluding membrane to alternate between the expanded occluding configuration and the collapsed lesser occluding configuration in synchrony with diastole and systole. An example of such a procedure may include the advancement of a replacement valve through a lumen of the catheter shaft. 
     The catheter shaft may be advanced over an aortic arch of the patient. The catheter shaft may be advanced or introduced to the aorta or other blood vessel transapically, transaortically, or transfemorally, to name a few approaches. 
     The flexible occluding membrane may be coupled to the catheter shaft at a center of the flexible occluding membrane. The flexible occluding membrane may be coupled to the catheter shaft at a location of the flexible occluding membrane offset from a center of the flexible occluding membrane. 
     INCORPORATION BY REFERENCE 
     All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the present disclosure are set forth with particularity in the appended claims. It should be noted that the drawings are not to scale and are intended only as an aid in conjunction with the explanations in the following detailed description. In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings. A better understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the present disclosure are utilized, and the accompanying drawings of which: 
         FIG. 1A  shows a side view of a temporary aortic valve apparatus, according to some embodiments; 
         FIG. 1B  shows a perspective view of the front of the temporary aortic valve apparatus of  FIG. 1A ; 
         FIG. 1C  shows a perspective view of the back and proximal lip of the temporary aortic valve apparatus of  FIG. 1A ; 
         FIG. 1D  shows a front view of the temporary aortic valve apparatus of  FIG. 1A ; 
         FIG. 1E  shows a perspective view of a distal end and the anchoring loop of the catheter shaft of the temporary aortic valve apparatus of  FIG. 1A ; 
         FIG. 1F  shows a magnified view of the distal end and the anchoring loop of the catheter shaft of the valve apparatus of  FIG. 1A  placed in vessel; 
         FIG. 1G  shows a side view of another temporary aortic valve apparatus, according to some embodiments; 
         FIG. 1H  shows a front view of the temporary aortic valve apparatus of  FIG. 1G ; 
         FIG. 2A  shows the temporary aortic valve apparatus of  FIG. 1A  positioned in the ascending aorta of a subject to be in its expanded configuration while the heart is in diastole, according to some embodiments; 
         FIG. 2B  shows the temporary aortic valve apparatus of  FIG. 1A  positioned in the ascending aorta of the subject to be in its collapsed configuration while the heart is in systole, according to some embodiments; 
         FIG. 3A  shows a transapical temporary aortic valve apparatus positioned in the ascending aorta of the subject to be in its expanded configuration while the heart is in diastole, according to some embodiments; 
         FIG. 3B  shows a transapical temporary aortic valve apparatus positioned in the ascending aorta of the subject to be in its collapsed configuration while the heart is in systole, according to some embodiments; 
         FIG. 4  shows a schematic of a testing apparatus used to test temporary aortic valve apparatuses, according to some embodiments; 
         FIG. 5A  shows the temporary aortic valve apparatus of  FIG. 1A  in its expanded configuration in the testing apparatus of  FIG. 4  when simulating diastole; 
         FIG. 5B  shows the temporary aortic valve apparatus of  FIG. 1A  in its collapsed configuration in the testing apparatus of  FIG. 4  when simulating systole; and 
         FIG. 6  shows a table of fluid volume distributions of temporary aortic valve apparatuses tested in the testing apparatus of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  shows a side view of a temporary aortic valve apparatus  100 .  FIG. 1B  shows a perspective view of the front of the temporary aortic valve apparatus  100 .  FIG. 1C  shows a perspective view of the back of the temporary aortic valve apparatus  100 .  FIG. 1D  shows a front view of the temporary aortic valve apparatus  100 .  FIG. 1E  shows a distal portion  110   a  of the temporary aortic valve apparatus  100 .  FIG. 1F  shows the distal portion  110   a  of the temporary aortic valve apparatus  100  placed in a vessel.  FIG. 1G  shows a side view of an embodiment of the temporary aortic valve apparatus  100 .  FIG. 1H  shows a front view of an embodiment of the temporary aortic valve apparatus  100 . 
     The temporary aortic valve apparatus  100  may comprise a catheter shaft  110  and a flexible occluding membrane  120  attached to the catheter shaft  110 . The flexible occluding membrane  120  may be attached to the catheter shaft  110  near the distal portion  110   a  of the catheter shaft  110 . The flexible occluding membrane  120  may have an axially distal end  120   a  and an axially proximal end  120   b.  A lateral side  126  of the flexible occluding membrane  120  is attached to the catheter shaft  110  such that the flexible occluding membrane  120  is axially aligned with the catheter shaft  110 , with both the distal end  120   a  and the proximal end  120   b  being attached to the flexible occluding membrane. As shown in  FIGS. 1E and 1F , the distal portion  110   a  of the catheter shaft  110  may include a large distal loop  112  at the distal end to aid in anchoring the temporary aortic valve apparatus  100 . The large distal loop  112  may include one or more radiopaque markers  114  to allow it to be visualized during a surgical procedure.  FIG. 1F  shows the large distal loop  112  anchoring the temporary aortic valve apparatus  100  in a vessel such as a blood vessel. The large distal loop  112  can appose the inner wall of the vessel and the friction therebetween can anchor the large distal loop  112  and the TAV  100  in place. In some embodiments, the large distal loop  112  is actuated between expanded and collapsed configurations so that that catheter shaft  110  can be engaged and disengaged from the vessel wall. In the collapsed configuration, the large distal loop  112  may be straightened by an advancable, internal guidewire or other mechanism. The collapsed (e.g., straightened) configuration of the loop  112  may facilitate the delivery of the TAV to the ascending aorta and/or its removal from the vasculature. The distal end portion  110   a  of the catheter shaft  110  may be pre-formed to have the large distal loop  112 . When the straightening guide wire is removed, the large distal loop  112  may resiliently return to its curved shape. Alternatively, the large distal loop  112  can be pre-formed to be straight and can be curved or looped with the advancement of a guidewire with a curved end therethrough. 
     The flexible occluding membrane  120  may be expandable and collapsible. Generally, when placed in a bodily vessel such as a blood vessel, the direction of fluid flow may dictate whether the flexible occluding membrane  120  is in its expanded or collapsed configuration. The flexible occluding membrane  120  may be conical in shape, with the conical shape tapering toward the distal end  120   a.  The flexible occluding membrane  120  may have a large proximal opening or gap  124  such that fluid (e.g., blood) flow in the direction of the taper causes fluid to flow into the proximal opening  124  to cause the flexible occluding membrane  120  to expand. When expanded, the circumferential or annular lip on the proximal end  120   b  of the flexible occluding membrane  120  may appose the inner wall of the bodily vessel. Generally, the circumferential or annular lip on the proximal end  120   b  is sized such that when expanded, it fully apposes the annular inner wall of the bodily vessel such as the ascending aorta (i.e., the diameter of the distal end  120   b  when expanded may be greater or equal to the diameter of the inner wall of the target bodily vessel). The distal end  120   a  of the flexible occluding membrane  120  may have a smaller opening or gap  122  which allows some fluid to pass through the expanded flexible occluding membrane  120 . The opening or gap  122  may be a cut-out section of the tip of the conical membrane  120 . In some cases, the flexible occluding membrane  120  may be biased to be in the expanded configuration even without fluid flow in the direction of the taper. When fluid (e.g., blood) flows in the opposite direction, fluid flowing past the outer surface of the flexible occluding membrane  120  may urge the flexible occluding membrane  120  to collapse. 
     As shown in  FIGS. 1A to 1D , the temporary aortic valve apparatus  100  may have the distal opening or gap  122  positioned closely relative to the catheter shaft  110 . Other locations of the distal opening or gap  122  are also contemplated. As shown in  FIGS. 1G and 1H , the opening or gap  122  may be spaced apart from the catheter shaft  110  while still being positioned at the distal tip  120   a  of the flexible occluding membrane  120 . A proximal, lateral portion  126   b  of the flexible occluding membrane  120  is attached to the catheter shaft  110  while a distal lateral portion  126   a  of the flexible occluding membrane remains free. Further locations of the distal opening or gap  122  are also contemplated. For example, the distal opening or gap  122  may be slightly offset from the distal tip  120   a  of the flexible occluding membrane  120 . While one distal opening or gap  122  is shown, having a plurality of distal openings or gaps is also contemplated. For example, there may be a plurality of distal openings or gaps  122  distributed about the distal tip  120   a  of the flexible occluding membrane in some embodiments. 
     As shown in  FIGS. 1E and 1F , the distal portion  110   a  of the catheter shaft  110  may include a large distal loop  112  at the distal end to aid in anchoring the temporary aortic valve apparatus  100 . The large distal loop  112  may include one or more radiopaque markers  114  to allow it to be visualized during a surgical procedure. 
       FIGS. 2A and 2B  show the temporary aortic valve apparatus  100  positioned in the aorta AOR of a subject. In particular, the temporary aortic valve apparatus  100  is positioned in the ascending aorta AA superior to the aortic valve AV. To position the temporary aortic valve apparatus  100  in this location, the temporary aortic valve apparatus may have been introduced percutaneous with a delivery catheter and navigated superiorly in the descending aorta DA and across the arch of the aorta AOA to reach the ascending arota AA. The temporary aortic valve apparatus  100  may be positioned so that the distal opening  122  is superior of the aortic valve AV, the right coronary artery RCA, and the left coronary artery LCA and so that the proximal opening  124  is inferior of the aortic arch AOA and superior of the Sinus of Valsalva. The proximal opening  124  may be positioned to be inferior of the arch of the aorta AOA, the brachiocephalic artery BA (which leads to the right subclavian artery RCA and the right common carotid artery RCCA), the left common carotid artery LCCA, and the left subclavian artery LSA. The large distal loop  112  can be expanded to appose the inner wall of the ascending aorta superior to the Sinus of Valsalva and the coronary ostia to anchor the temporary aortic valve apparatus  100  in place. 
     In  FIG. 2A , the heart is in diastole and the leaflets of the aortic valve AV have closed. In the presence of atrioventricular damage, there would be aortic regurgitation at the aortic valve AV in diastole. The temporary aortic valve apparatus  100  may therefore assume the expanded configuration, with the flexible occluding membrane  120  expanded and the outer circumferential lip of the distal end  120   b  of the flexible occluding membrane  120  opposing the inner wall of the ascending aorta AA. The flexible occluding membrane  120  may be biased to be in the expanded configuration. Blood flow back toward the aortic valve AV as shown by arrows  200  may pass through the expanded flexible occluding membrane  120  to pass through the openings  124  and  122  to perfuse the right coronary artery RCA and the left coronary artery LCA. 
     In  FIG. 2B , the heart is in systole and the leaflets of the aortic valve AV have opened. Blood flow through the aortic valve AV and aorta AO as indicated by arrows  201  may cause the flexible occluding membrane  120  to collapse and the temporary aortic valve apparatus  100  to therefore assume the collapsed configuration. The large distal loop  112  can continue to anchor and maintain the position the temporary aortic valve apparatus  100  throughout the cardiac cycle in both systole and diastole. 
     As described above, the temporary aortic valve apparatus  100  will typically be configured to be delivered percutaneous. For example, the temporary aortic valve apparatus  100  may have been delivered transfemorally as shown in  FIGS. 2A and 2B . Temporary aortic valve apparatuses of the present disclosure may be configured for other approaches as well. For example, a transaortic approach may be used instead of a transfemoral approach to introduce the temporary aortic valve apparatus  100  to the target location shown in  FIGS. 2A and 2B . In other examples, a transapical approach as described below and herein may be used. The temporary aortic valve apparatus  100  will typically be introduced to the target treatment site through the inner lumen of a delivery catheter. The delivery catheter may constrain the flexible occluding membrane  120  to be in its collapsed configuration so that the delivery catheter and the temporary aortic valve apparatus  100  may be navigated through the vasculature in a minimal cross-section configuration or otherwise introduced in a minimal cross-section configuration. 
       FIG. 3A  shows a transapical temporary aortic valve apparatus  300  advanced through the left ventricle of the heart HRT to be positioned in the ascending aorta AA. The transapical temporary aortic valve apparatus  300  may have device components similar to those of the percutaneous temporary aortic valve apparatus  100 . The transapical temporary aortic valve apparatus  300  may comprise a catheter shaft  310  coupled to a flexible occluding membrane  320 . The flexible occluding membrane  320  may be conical in shape and have a taper in the proximal direction, that is, the distal opening or gap  324  at the distal tip is larger than the proximal opening at the proximal tip of the flexible occluding membrane  320 . The distal end of the temporary aortic valve apparatus  300  may have a distal loop, similar to the loop  112  of the temporary aortic valve apparatus  100  described above and herein, to facilitate anchoring within the aorta. 
     In  FIG. 3A , the heart is in diastole and the leaflets of the aortic valve AV have closed. The temporary aortic valve apparatus  300  may therefore assume the expanded configuration, with the outer circumferential lip of the distal end of the flexible occluding membrane  120  opposing the inner wall of the ascending aorta AA. Blood flow back toward the aortic valve AV as shown by arrows  300  may pass through the expanded flexible occluding membrane  320  to pass through the openings  324  and  322  to perfuse the right coronary artery RCA and the left coronary artery LCA. 
     In  FIG. 3B , the heart is in systole and the leaflets of the aortic valve AV have opened. Blood flow through the aortic valve AV and aorta AO as indicated by arrows  301  may cause the flexible occluding membrane  320  to collapse and the temporary aortic valve apparatus  300  to therefore assume the collapsed configuration. 
     Experimental 
     The inventor has tested a prototype cone-shaped membrane occlusion apparatus substantially the same as the apparatus  100  as described above. Occlusion devices with different gap cross-sectional area to aortic cross-sectional area ratios were tested. Three prototypes with reducing gap:aorta cross-sectional area ratios—35%, 15%, and 0%—were tested in a flow chamber of simulated acute severe aortic regurgitation. Correspondingly, increasing in forward cardiac output volumes, coronary flow:aortic regurgitant volume ratios and reduction in aortic regurgitant volumes were observed (p&lt;0.001). Based on such experimentation, an optimal gap:aorta cross-sectional ratio for the cone-shaped membrane occlusion device can be determined. A clinically useful percutaneous device for the management of acute severe aortic regurgitation (e.g., to provide hemodynamic support) may be developed based on this determined optimal ratio. 
       FIG. 4  shows a schematic of a testing apparatus  400  used to test the temporary aortic valve apparatuses. The apparatus comprises an input reservoir tank  410  storing fluid which flows through the channel  415  to provide fluid flow to a main channel  420  where the temporary aortic valve testing site  425  is located. The fluid may also flow through the main channel  420  to an output reservoir tank  430  and a cardiac output volume measurement apparatus  435 . On the opposite side, the fluid may also flow through the main channel  420  through channel  450  which leads to an aortic regurgitant volume measurement apparatus  455 . The fluid may also flow through the main channel  420  through a channel  460  leading to a coronary flow volume measurement apparatus  465 . The channels  415 ,  420 , and  450  may comprise clear polyvinyl chloride (PVC) tubing with a 2.54 cm internal diameter and the channel  460  may also comprise a clear polyvinyl chloride (PVC) tubing but with a 0.635 cm internal diameter. The PVC tubings used may be obtained from Kuriyama of America, Inc. of Schaumburg, Ill. 
     The testing apparatus  400  may further comprise valves (e.g., electrically actuated ball valves 24VAC available from Dynaquip Controls Corp. of St. Clair, Mich.)  440  and  445 . The valve  440  may separate the channel  415  and the main channel  420 . The valve  445  may separate the main channel  420  with the channel  450 . When the valve  445  is open, fluid may be allowed to flow through the channel  450  to reach the aortic regurgitant volume measurement apparatus  455 . When the valve  445  is open, more fluid is allowed to flow through the channel  460  to reach the coronary flow volume measurement apparatus  460 . 
     The valves  440 ,  445  may be open and closed to provide pulsatile fluid flow through the main channel  420 , simulating the pulsatile blood flow in the aorta. Pulsatile flow conditions of the ascending aorta with or without induced aortic regurgitation (AR) may be simulated. The automatic and adjustable timing cycles of the two valves  440 ,  445  may be created via an electrical circuit with a repeat cycle time delay relay (e.g., available from Dayton Electric Co. of Niles, Ill.) and two control transformers 120/24 VAC (e.g., available from Veris Industries of Portland, Oreg.). The two valves  440 ,  445  may be coordinated such that normal flow conditions with an intact aortic valve and acute wide-open aortic regurgitation can be simulated at the testing site  425 . 
     The tested temporary aortic valve (TAV) apparatus  100  comprised a cone-shaped latex membrane  120  having a thickness of 0.33 mm. The membrane  120  was affixed to a standard 5-Fr. standard catheter  110 . The dimensions of the latex cone were as follows: the diameter of the cone-opening (circular lip) at the proximal end  120   b  was slightly larger than the diameter of the inner tubing wall (2.54 cm) at the test site  425  representing the ascending aorta. The slightly larger size was chosen to ensure sufficient apposition of the conical membrane  120  to the aorta during diastole when the conical membrane  120  is open. The depth of the conical membrane, from proximal lip to distal tip, was arbitrarily set at 5 cm. The gap or opening  122  was created by cutting the tip of the conical membrane  120  such that the cross-sectional area of the gap-opening  122  with respect to the aorta can be specified. 
     While certain dimensions, parameters, and component materials of the tested temporary aortic valve (TAV) apparatus  100  are disclosed above, it is to be understood that such dimensions, parameters, and component materials are provided as examples only. It will be understood that in practice, the temporary aortic valve apparatus  100  may encompass a variety of dimensions, parameters, and component materials without departing from the scope of the present disclosure. 
       FIG. 5A  shows the temporary aortic valve apparatus  100  in its expanded configuration in the testing site  425  of the testing apparatus  400  when simulating diastole. Retrograde fluid flow in the direction indicated by arrow  500  can enter the proximal opening  124  to expand the flexible occluding membrane  120 . Alternatively or in combination, the conical membrane  120  may also assume its original expanded configuration in the absence of forward fluid flow. The conical membrane  120  in the expanded configuration may provide retrograde resistance to aortic regurgitation while the pre-fabricated gap  122  may control residual aortic regurgitation and allow for coronary filling. 
       FIG. 5B  shows the temporary aortic valve apparatus  100  in its collapsed configuration in the testing site  425  of the testing apparatus  400  when simulating systole. Forward fluid flow in the direction indicated by arrow  501  collapses the flexible occluding membrane  120 . 
     Flow volumes were collected at respective sites representing the forward cardiac output, aortic regurgitant flow, and coronary flow over a 1-minute run comprising 12 cycles. Volumes were measured under the conditions of baseline normal (with intact aortic valve; ball-valve (B) closed throughout cycles), simulated acute severe aortic regurgitation (AR) (alternating opening and closing of ball-valves (A) and (B) per cycle) and acute severe AR with TAV protection. The TAV prototypes tested had 35%, 15%, and 0% gap:aorta cross-sectional area ratios at the cone-tip, respectively. Data for each condition was averaged over 3 runs. All volume measurements were collected in liters (l). Statistical analyses of the volume differences during the various conditions were performed using ANOVA. 
     Results. The three prototypes with reducing gap:aorta cross-sectional area ratios (35%, 15%, 0%) were tested in the flow chamber of simulated acute severe aortic regurgitation (e.g., the testing apparatus  400 ). Correspondingly, increasing in forward cardiac output volumes, coronary flow:aortic regurgitant volume ratios and reduction in aortic regurgitant volumes were observed (p&lt;0.001). The large distal catheter loop of the prototype devices were successful in immobilizing the conical membrane from any undue axial movements along the length of the tubing or mock “aorta.” 
       FIG. 6  shows a table of the experimental results. Compared to the normal baseline normal condition, simulated acute severe AR showed a drop in the forward cardiac output volume (from 21.12±0.49 to 14.43±0.18), decrease in the coronary flow volume (from 1.97±0.06 to 1.78±0.01) and a sharp presence of aortic regurgitant volume (From 0 to 8.07±0.08). 
     With membrane TAV protection during simulated acute severe AR, there was a significant increase in the forward cardiac output volumes as the TAV gap size decreased from 35% to 0% (p&lt;0.001). Along with the smaller TAV gap sizes, the aortic regurgitant volume significantly decreased while the coronary flow:aortic regurgitant ratio significantly increased (both with p&lt;0.001). The absolute coronary flow volume did not drop with TAV deployment of any gap size. 
     It will be understood that the results were conducted with the prototype TAV apparatus  100  and that variations to the experimental results may occur with different testing parameters and/or modifications to the TAV apparatus  100 . The experimental results are provided as examples. 
     Discussion. Prior 3-balloon TAV devices were also studied. These 3-balloon TAV devices may be challenged due to the fixed nature of the gap provided. (Ho P C, Minim Invasiv Ther Allied Technol 2008; Ho P C, J Med Eng Technol 2011; Ho P C, J Heart Valve Dis 2013.) During systole, the fixed TAV gaps from the inflated balloons may represent forward aortic flow resistance and may affectively create an artificial stenosis. Although calculated at moderate range, the effective TAV aortic stenosis could limit its application in patients with a compromised left ventricle. Subsequent addition of balloon counter-pulsation to the balloon-based TAV device, however, could potentially lessen forward aortic flow resistance. (Ho P C, Minim Invasive Ther Allied Technol 2011.) 
     The TAV devices of the present disclosure may include conical membranes that may be collapsible during systole and fully expandable in diastole based on the passive forces of the aortic flow, with a gap-to-aorta cross-sectional area ratio that can be tailored to optimize aortic regurgitation protection and coronary flow. The conical membrane of the tested TAV device may have a shape may cause the lip of the conical membrane to be in apposition with the aortic (tubing) wall, such that the diastolic regurgitant flow (for coronary filling) could be controlled at the pre-specified gap at the cone-tip. The elegance of the conical membrane temporary aortic valve was demonstrated by the collapsibility of the conical membrane due to the passive forces of the aortic flow. As the lip of the conical membrane becomes in apposition with the tubing or mock “aortic” wall during diastole, diastolic regurgitant flow (e.g., for coronary filling) could be controlled at the pre-specified opening or cap at the membrane tip. Without the concern for systolic flow obstruction in the test system versus in vivo, a lower limit of the gap:aorta cross-sectional area could be determined. Because the mathematical model for the 3-balloon TAV model calculated the gap to be at 35% of the aortic cross-sectional area, the selection for the membrane TAV gap sizes in this study began at 35%, followed by 15%, and 0%. While these specific gap size percentages were tested, other TAV gap sizes such as 50%, 40%, 30%, 20%, or 10% are also contemplated. 
     The 0% TAV gap was chosen as a control for the study construct including the flow apparatus and the membrane TAV prototype. Ideally, no AR would be expected at 0% TAV gap. In the experiment using the TAV with 0% gap, however, the aortic regurgitant volume was quite high even though it was much less than using TAV with larger gaps (table  1 ,  FIG. 6 ). The excessive AR findings may be explained by the TAV prototype assembly  100  and the experimental setup  400 . The imperfect seal of the TAV prototype  100  may be caused by inadequate apposition of the cone-lip to the tubing wall and/or device-related mal-apposition against the tubing wall. In this regard, the TAV devices of the present disclosure may be manufactured to provide improvements over the tested, pre-clinical TAV prototype device based on factors such as membrane material selection, catheter stiffness and french-size selection, and mounting technique of the membrane to the catheter  110 . 
     With decreasing TAV gap sizes, the gradual improvements in the forward cardiac output volumes and reduction in the aortic regurgitant volumes are encouraging results. The lack of coronary flow volume response can be viewed as a positive finding in conjunction with the improvements in the coronary:regurgitant volume ratios. Unintentional allowance of significant AR by the membrane TAV prototype may explain this lack of coronary flow improvement, which may improve with further manufacturing as mentioned. In a published study of a temporary valve with no built-in gaps, however, device deployment caused further decline in coronary flow rates already compromised by induced acute aortic regurgitation (Salizzoni S, J Thorac Cardiovasc Surg 2009). Our membrane TAV prototype  100  did not reduce the coronary flow during deployment while sustaining a significant reduction in aortic regurgitation. 
     Refinement of the gapped device may be contingent upon redefining the low-limit for the size of the gap  122  in the membrane TAV device  100 , such that it can provide the maximal AR protection without restricting coronary flow. With this approach of device optimization, the coronary flow could rise at improved TAV AR protection. The high speed of the aortic regurgitant jet has been attributed to coronary flow reduction at severe range acute AR. Reversal of diastolic coronary flow due to Venturi effect from the high speed regurgitant jet has been suggested (Ardehali A, J Am Coll Cardiol 1995). Our in vitro flow apparatus  400  also may not be able to reproduce the physiologic “suction” wave of coronary microvasculature in diastolic filling (Davies JE, Circulation  2006 ). By reducing the speed of the aortic regurgitant flow with the membrane TAV, diastolic coronary filling could be optimized by lessening likelihood for coronary flow reversal in significant AR. The regurgitant blood volume may be more likely to enter the coronary bed with its lower outflow pressure in the right atrium and its “suction” effect of diastolic filling versus the left ventricle. 
     The study performed may also be limited by the typical inability of in vitro flow models such as the flow model  400  to completely simulate physiologic conditions. Also, the TAV prototype  100  used was an approximation of the pre-clinical vision with contemplated improvements in material selection and manufacturing processes as discussed. As such, the study provides qualitative proof of concept evaluation of a promising membrane transcatheter TAV device  100 . The findings suggest a lower limit for the gap:aorta dimensional ratio could be determined to optimize aortic regurgitation protection while allowing for optimal diastolic coronary filling. 
     While preferred embodiments of the present disclosure have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the present disclosure. It should be understood that various alternatives to the embodiments of the present disclosure described herein may be employed in practicing the present disclosure. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.