Patent Publication Number: US-2011071351-A1

Title: Apparatus and method for simulation of diastole and visualizing the diastolic state of an aortic valve and root during cardiac surgery

Description:
RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/245,540, entitled “APPARATUS FOR SIMULATION OF DIASTOLE AND VISUALIZING THE DIASTOLIC STATE OF AN AORTIC VALVE AND ROOT DURING CARDIAC SURGERY,” filed Sep. 24, 2009, which is hereby incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     This disclosure relates generally to methods and devices for performing aortic valve surgery, and more particularly, to methods and devices for assessing the quality of aortic valve repair and competence of the aortic valve during open-heart surgery. 
     2. Discussion of Related Art 
     Valvular heart disease is a leading cause of morbidity and mortality in the United States and abroad. The aortic valve separates the main pumping chamber of the heart (left ventricle) from the main blood vessel that exits the heart, called the aorta. Its anatomic location is within what is called the “aortic root,” the very first segment of the aorta, housing the aortic valves and the origins of the coronary arteries. Aortic valves may fail by either blockage (stenosis) or regurgitation/insufficiency (leaking). Specifically, aortic valve “regurgitation” or “insufficiency” (leaking) can lead to heart failure symptoms (shortness of breath, exercise intolerance, accumulation of fluid), frank deterioration of heart contractile function (pumping ability), and certain heart rhythm disturbances. Typically, if these signs or symptoms are encountered in the setting of at least moderate grade aortic valve leaking, intervention is indicated to repair or replace the valve. 
     The vast majority of surgically treated valves are excised and replaced with either a “tissue” or “mechanical” heart valve, each fraught with disadvantages. Tissue valves (bovine, porcine, or other animal tissue formed to function as a valve) are limited by their durability, lasting anywhere from 7 to 15 years on average. Mechanical valves (typically pyrolite carbon) last much longer but require permanent anticoagulation (thinning of the blood) to prevent strokes, with accompanying morbidity of strokes or clotting complications. Recently, “transcatheter” valves have been developed whereby a tissue valve is mounted on a collapsible stent and delivered into the proper anatomic location in a minimally invasive fashion. While suitable for certain patients with aortic “stenosis” (blockage), they are not suited for leaking aortic valves at the current time. For young patients in particular, whose lifespan would exceed that of a tissue valve (requiring re-intervention at a later time) and who want to avoid life-long blood thinners (anticoagulation), aortic valve repair is particularly attractive. In theory, native valve tissue that has been surgically rendered to be competent should have a longer durability than tissue valves, and not require anticoagulation as with a mechanical valve. Clinical practice has revealed that repair, rather than replacement, of a different heart valve, the mitral valve, is associated with the best long term outcomes. It is anticipated that the same will be observed with aortic valve repair. 
     The ultimate “test” of the success of aortic valve repair is echocardiographic (ultrasound) evaluation of the valve after discontinuation of support form the heart-lung machine. At this point in surgery, it is difficult, dangerous and cumbersome to re-access the valve for attempts at re-repair, and while the echo can show valve leaking with great sensitivity, it often does not elucidate the specific cause of the leaking to guide repair or re-repair. Thus, an important problem with aortic valve repair is the inability to assess the competency of the repaired valve under physiologic conditions (water-tight pressurization of the aortic root, with blood or crystalloid fluid flowing towards the valve). 
     The current disclosure and associated method attempt to overcome this limitation, allowing for the direct or indirect inspection of the aortic valve under physiologic conditions. Other approaches that claim to accomplish this task do so either with only incomplete pressurization of the aortic root or with flow characteristics that are non-physiologic. In order to simulate physiologic diastole (the portion of the cardiac cycle when the aortic valve is closed and expected to be competent), the following features must be present: a) temporary but complete sealing of the aortic access incision with a generally water-tight fit, and ideally b) flow of fluid directed towards the aortic valve from a large caliber conduit, roughly equivalent to that of the junction between the aortic root and ascending aorta (“sino-tubular junction”), c) ability to measure flow and pressure within the aortic root. The feature noted in “b” above is particularly important in that any device that would instill fluid volume into the aortic root should ideally not do so through a small or medium bore connection, since this does not represent how blood flows back towards the aortic valve during diastole: the entire column of blood that was rushing forward away from the heart during contraction (systole) comes back from elastic recoil towards the aortic valve through the aorta, a very large diameter conduit (roughly 20-40 mm). One aspect of the current disclosure, aside from having the mentioned features, is the ability to see clearly into the aortic root during simulation of physiologic diastole to visualize exactly how the aortic valve is leaking in order to direct repair. Further, the approaches set forth in this disclosure are designed to allow re-repair of the valve over and over again without the need to re-open a surgically closed (sutured) aorta or the need to terminate cardiopulmonary bypass support (heart-lung machine). 
     SUMMARY OF THE DISCLOSURE 
     Different embodiments of the device allow for reversible, water-tight attachment of a chamber or disc to either the opened/transected aorta itself, or to a short open tube, typically of a prosthetic material i.e., fabric, polyester or other material than is sutured to a portion of the opened or transected aorta or aortic root. In some versions of this device, methods for reversible attachment may also be engineered into the short open tube. In other iterations, a device is sutured directly to the opened or transected aorta, and can expand to enable valve assessment and then contract down to a position very close to the suture line, in order to re-access the valve for re-repair, etc. A method is described for surgery to correct aortic valve leaking, wherein the surgeon manipulates aspects of the ventriculo-aortic junction, the area above the aortic valve, and the aortic valve leaflets themselves and assesses the valve repair using said chamber or disc to assess the valve repair over and over again until the aortic valve is rendered competent. 
     In one embodiment, a device that comprises a partially or completely transparent chamber is attached to the opened or transected aorta at the site of the incision made to access and visualize the aortic valve during open heart surgery. If aortic root (aneurysm) replacement is required, or a complete transection of the aorta is desired to access the valve, the chamber attaches to a short open tube of fabric or other material, which is sutured to the aorta or ventriculo-aortic junction. The device will be available in size ranges corresponding to typical sizes of the anatomic sino-tubular junction, roughly 20 to 40 mm. The chamber proximal end is configured to have a reversible attachment mechanism (e.g., magnetic, external cinching or snaring over a groove or ridge, vacuum or other mechanism). A feature of the device is a mechanism for viewing the aortic valve through at least a portion that is transparent, or by incorporating a mechanism for videoscopic or ultrasonic assessment of an aortic valve. Yet another feature is the ability to simulate the diastolic phase of the cardiac cycle relative to the aortic root by creating closed space pressurization of the device attached to the surgically transected aorta or short open tube, and filling of the chamber with fluid in a generally water-tight fashion, and monitoring of the closed system with pressure sensors and relief valves to reproduce the normal physiologic characteristics of diastole. The distal end of the chamber may be closed, or tapered to a smaller open end to connect to tubing that will deliver fluid into the chamber, with approximate sizes ranging from 3/16 inch to ½ inch diameter. There may be Luer lock connector or other port attachment sites for pressure monitoring or relief valves, or delivery of said fluid. The ports may comprise one-way valves or entry sites for introduction of video-scopes or ultrasound transducers into the chamber. The device is then removed in order to gain the most direct access to the aortic valve and root for repair or re-repair the valve until a satisfactory result is obtained. 
     Various iterations of the device are conceived where some of the viewing area comprises a magnification or distortion lens, as well as wherein the attachment mechanism is aided by incorporation of silicone washers, for example. Where magnets are used in either or both of the chamber proximal end and the short open tube, there may be tabs associated with each to ease un-coupling. In another embodiment, the device is comprised of a transparent disc, rather than a chamber, reversibly attachable to the aorta or to a short open tube in a water-tight fashion, as described. A reversible attachment mechanism may have a peripheral groove or ridge on the proximal end of the chamber or disc so that a snare or tourniquet can be secured externally around the aorta or short open tube, to effect a water-tight seal. 
     Other embodiments of the device may include attaching an expandable tube or cylinder to the transected aorta to the function as the “chamber” described above. Valve assessment may be accomplished by closed pressurization of the expandable tube with fluid or blood. The expandable tube may incorporate a transparent window or have ports for indirect visualization of the valve with, for example, videoscopy or ultrasound. The distal end of the tube can be clamped with a standard vascular clamp in order to close the system for valve assessment. A feature of this embodiment is that after a valve assessment is done, the tube or cylinder is collapsed down to a small length, e.g., less than 50% of its expanded length but ideally down to less than 20 mm so that access to the valve will be unimpeded for repair or re-repair. These collapsible designs may do so by, for example, roll-down or fold-down (accordion-type) mechanisms. This design eliminates the need to physically attach a chamber to the short tube or aorta over and over again. A similar iteration would be where the tube was not collapsible, but still comprised a transparent window or ports for ultrasound/video. The valve can be re-accessed over and over again by making an incision in the tube and suturing it together to create a closed system for valve assessments. 
     Either the expandable tube/cylinder or the short open tube may include a cinching mechanism, possibly by pre-sutured purse-string or strings circumferentially woven into it. The purse-strings may also pass through other material to buttress the needle entry sites. This construction is intended to manipulate the size of the aorta above the valve or at the level of the aortic root (which may be mechanisms used to restore leaking valve competency), as well as to provide a mechanism for securing a transparent disc or chamber that has a peripheral groove or ridge to mate with the cinching mechanism. 
     The method in which the device will be utilized is as follows. Open heart surgery is performed in the standard fashion, using the heart-lung machine. The aorta is opened above the sino-tubular junction, and a dissection is made down to the ventriculo-aortic junction if aortic root replacement or manipulation is required. If a modular device is used, a short open tube is sewn either to the aorta above the valve or to the ventriculo-aortic junction (i.e., during aortic root replacement with aortic valve re-implantation). A closed system is created by attaching a transparent chamber or disc to either the short open tube, or to the opened (transected) aorta itself. Clear fluid (or blood, if ultrasound is used), such as crystalloid cardioplegia (a standard solution used to maintain and protect an arrested heart), is pumped through plastic tubing connected to the chamber or disc which is filled with the fluid while monitoring flow amount and pressure in the aortic root, in a generally water-tight fashion. The surgeon directly (through the transparent chamber) or indirectly (by video or ultrasound) visualizes the aortic valve in a physiologic closed position, and any mechanism of retrograde leaking is identified. Fluid flow is stopped, and the chamber/disc is detached in order to have the most direct access possible to the aortic valve. The valve is repaired or re-repaired as needed, and the device is then re-attached for a new assessment, and repeated until a satisfactory result is obtained (minimal residual leaking). The device is removed for the last time, and the aortic incision is re-approximated. The patient is separated from the heart-lung machine and clinical assessments are made as usual. 
     In one embodiment, the clinical problem being addressed is the difficulty in repairing leaking aortic valves because the etiology of valve leaking cannot be easily elucidated with conventional means, and because repair maneuvers cannot be adequately tested until after the patient is weaned off of the heart-lung machine, which is inconvenient. The proposed methods and devices may be used to reversibly create a generally water-tight closed space in the aortic root: the space between the ventriculo-aortic junction (where the aortic valve emerges from the left ventricle) and the tubular ascending aorta (above the aortic valve) after an incision is made in the aorta above the valve. A device that is usually at least partially transparent is secured into position above the valve, and the aortic root is pressurized with fluid, and the aortic valve is visualized. These devices are especially intended to allow the surgeon to visualize the aortic valve in its closed position, under conditions that are physiologic (fluid infusion into the aortic root, with pressures up to 150+ mmHg), and to identify how retrograde leaking is occurring. There are two general ways in which these devices would be used. The first, is where an incision is made just above the aortic valve and a device can be secured within the opened aorta in a reversible fashion (e.g., cinching or snaring). The causes of the leak are determined, and the device is removed and the aortic valve repaired. The device is then re-attached/secured in position and the aortic root is again pressurized with fluid to see if the repair was successful. If not, the cause is seen and the device removed so that re-repair can be attempted. This cycle continues until a satisfactory result is obtained, and the aorta is closed to complete surgery. The second general way in which this device can be used is to have it couple with a short open tube, usually of fabric, and this short open tube will have complementary features to enable reversible attachment of the device described above, with more versatility as to how reversible attachment can be achieved. The short open tubes would generally be of identical material and characteristics of commercially available fabric vascular grafts, and with removal of any associated connecting mechanism located at an end of the tube, it would be able to be appropriately used as a vascular replacement graft if desired. This is particularly anticipated for aortic root aneurysm surgery where aortic valve re-implantation is planned: where the aortic valve is dissected free from its native attachments and re-implanted into a vascular fabric graft. One additional feature is the ability to manipulate the diameter of the short open tubes, possibly by integrated purse-string or strings, which may be desirable during some forms of aortic valve repair. In some iterations, the short open tube itself may be discontinuous (e.g., a cut circle in axial view) so that it can be slid under the still-intact (only partially transected) aorta during aortic valve repair. 
     One aspect of the disclosure is directed to a device for evaluating an aortic valve after opening an aorta distal to the aortic valve. In one embodiment, the device comprises a body defining a chamber. The body has a generally circular proximal open end and a distal end, the proximal open end being configured to be reversibly attachable to one of the aorta and a short open tube distal to the aortic valve in a generally water-tight fashion. At least a portion of the body is transparent to view the aortic valve. 
     Embodiments of the device may include configuring the body in a generally cylindrical in shape in which the proximal open end of the body has a diameter of 20 to 40 mm and the distal end tapers from the proximal open end to define an opening with a diameter of less than 15 mm. The portion of the body may further include at least one magnifying or distortion lens. The proximal open end may be configured to be reversibly attachable to the short open tube that is fabricated from flexible material, an end of the short open tube having an opening with a diameter of 20 to 40 mm. The short open tube may embody a sewing cuff having an integrated purse-string or snare. The device may further comprise a mechanism for reversible attachment of the body to the short open tube. In one embodiment, the mechanism includes at least one magnet associated with either or both of the short open tube and the proximal open end of the body. At least one of the proximal open end of the body and short open tube may comprise a water-tight washer of silicone or other material. The device may further comprise a mechanism for reversible attachment, the mechanism including at least one generally circumferential groove or ridge at or near the proximal open end of the body such that an external snare or purse-string is used to secure the at least one groove or ridge within the aorta or short open tube. In one embodiment, the mechanism for reversible attachment may comprise at least two sets of joining clasps on both the body proximal open end and the sewing ring. The body may further include at least one port. 
     Another aspect of the disclosure is directed to a device for evaluating an aortic valve after opening an aorta distal to the aortic valve, the device comprising a generally circular disc having a transparent portion to view the aortic valve, the disc being configured to be reversibly attachable to one of the aorta or a short open tube distal to the aortic valve in a generally water-tight fashion. 
     Embodiments of the device may include configuring the disc to have a diameter of 20-40 mm. The disc may further comprise at least one magnifying or distortion lens. The disc may be configured to be reversibly attachable to the short open tube that is fabricated from polyester or other fabric material having diameter of 20-40 mm or to the aorta itself. The short open tube may comprise at least one integrated purse-string or snare. The at least one of the disc and the short open tube may include a water-tight washer. The device may further comprise a mechanism for reversible attachment of the disc to the aorta distal to the aortic valve, the mechanism including at least one magnet provided in one of the disc and the short open tube. In one embodiment, a mechanism for reversible attachment of the disc to the aorta distal to the aortic valve includes at least two sets of joining clasps on both the disc and the short open tube. The device may further comprise a mechanism for reversible attachment of the disc to the aorta or the short open tube distal to the aortic valve, the mechanism including at least one generally circumferential groove or ridge around the disc such that an external snare or purse-string is used to secure the at least one groove or ridge within the aorta or the short open tube. The disc may further comprise at least one opening or port. 
     Yet a further aspect of the disclosure is directed to a device for evaluating an aortic valve after opening an aorta distal to the aortic valve, the device comprising a non-rigid cylinder having a 20-40 mm diameter proximal end, wherein at least a portion of the cylinder being transparent to view the aortic valve. In one embodiment, the tube or cylinder is collapsible to a length of less than 50% of its extended length, by one of a roll-down or a folding mechanism. 
     The present disclosure will be more fully understood after a review of the following drawing figures, detailed description and claims. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. For a better understanding of the present disclosure, reference is made to the figures which are incorporated herein by reference and in which: 
         FIG. 1  is an exploded representation of one embodiment of a device showing a short open tube separated from a reversibly attachable chamber; 
         FIG. 2  represents the device showing a mechanism to reversibly attach the chamber to the short open tube, such as by magnetic force; 
         FIG. 3  is an enlarged representation of an embodiment of the disclosure showing an alternate mechanism for reversibly attaching the chamber to the short open tube by clips; 
         FIG. 4  is a representation of a device comprising a chamber and tubing connected to a distal end of the chamber; 
         FIG. 5  is another representation of a chamber illustrating a transparent window or magnifying/distortion window of the chamber; 
         FIG. 6  is another representation of the method and an embodiment of a device having a proximal open end joined to a short open tube, with the aortic valve visualized as fluid fills the chamber and attached aortic root in a generally water-tight fashion; 
         FIG. 7  is a representation of a device comprising a tube containing a port or one-way valve for receiving of a video-scope or ultrasound probe; 
         FIGS. 8A-8F  illustrate several mechanisms by which an expandable device may be collapsed to a smaller length in order to make valve repair assessments; 
         FIGS. 9A-9E  illustrate views of a cinching or snaring mechanism incorporated into a short open tube with at least one integrated purse-string suture; 
         FIGS. 10A-10C  illustrate another embodiment of a disc or distally closed cylinder having an axially arranged groove to enable reversible attachment by an external cinch or snare associated with a short open tube or the aorta itself; 
         FIG. 11  illustrates another embodiment of a transparent disc that is reversibly attachable to the aorta itself, by external snaring that couples with a groove or ridge on the disc, the disc having a port of entry for delivering fluid into the aortic root; and 
         FIG. 12  illustrates a representation of the device as a transparent chamber, which has a groove or ridge peripherally oriented on its proximal open end that can be snared externally within the aorta or a short tube. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     This disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The principles disclosed herein are capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     With reference to  FIG. 1 , a short open tube  1  may be fabricated from polyester, Dacron, expanded polytetrafluoroethylene, or any other material (e.g., xenograft tissue, such as bovine pericardium or porcine small intestinal submucosa) suitable for suturing to the native aorta (i.e., the large, main blood vessel that exits the heart). The short open tube  1  is generally a short, open-ended cylinder, with diameter ranging 20 to 40 mm, corresponding to the range of size of the normal aorta at a level above the valve (i.e., the sino-tubular junction). The short open tube  1  is sewn to the transected aorta after the heart is stopped during open heart surgery. A reversible connecting mechanism  2  of the short open tube  1  and a proximal open end  6  of chamber  5  each comprise open rings and mechanisms for reversibly attaching to one another. Specifically, the reversible connecting mechanism  2  and the proximal open end  6  each exhibit a generally circular shape and whose unattached surfaces may respectively comprise washer rings  3 ,  4  to effect a generally water-tight seal when adjoined. Both the distal end of short open tube  1 , comprising connecting mechanism  2 , and the proximal open end  6  of chamber  5  represent open rings and externally have attached fixation tabs  8  and  9  for grasping when attempting to separate the device after it has been assembled. The chamber  5  may be dome shaped, and has a proximal open end  6  and a distal end  7 . In this configuration, the distal end  7  tapers to a smaller generally cylindrical opening for attachment to tubing when the device is in use. Chamber  5  may also have one or more Luer lock connectors or port attachments  10  for fixation of additional devices fitted to the Luer lock connector, such as syringes, pressure gauges, tubing, overflow valves, etc. 
     With reference to  FIG. 2 , an embodiment of the reversible attachment mechanism is illustrated. The connecting mechanism  2  of the short open tube  1  may be comprised of a silicone or rubber washer  3  on its distal end. In this embodiment of the disclosure, within the center of the connecting mechanism  2  is either a ferro-magnetic core or a magnet  11 . Similarly, the proximal open end  6  of chamber  5  may be comprised of a silicone or rubber washer  4 , and in this embodiment, within the center of proximal open end  6  is a complimentary magnet or ferro-magnetic core  12  in the shape of a ring. Magnets used may comprise rare-earth magnets. The magnetic forces are sufficient to enable reversible joining of the proximal open end  6  of the chamber  5  to the short open tube  1  by connecting mechanism  2 , and resist separation at chamber pressures of up to 350 mm Hg. 
       FIG. 3  is yet another embodiment of a method by which the proximal open end  6  of the chamber  5  may be reversibly joined to the short open tube (not shown). Internal and external pinch tabs  13 ,  14  snap into place over the distal end of the short open tube (not shown). A silicone or rubber washer  4  ensures water-tight seal, and pinch tabs  13 ,  14  are engineered to resist separation from the short open tube at chamber pressures up to 350 mm Hg. 
       FIG. 4  is a representation of another embodiment of the chamber, which is generally cylindrical shaped. Distal end  7  comprises a short inflow cylinder  15 , while the remainder of the distal end is closed. Both inflow tubing  16  and inflow cylinder  15  are of a caliber generally in the 3/16 inch to ½ inch range. 
       FIG. 5  is yet another representation of chamber or cylinder/tube  5 , illustrating a transparent window, or a magnifying or distortion lens  17  within at least one location in the chamber or cylinder/tube. In this illustration, the distal end  7  is tapered to receive tubing in order to fill the chamber and aortic root with fluid in a generally water-tight fashion. Another iteration would have the chamber  5  be a tube or cylinder of fabric or other material that is open on the distal end and can be clamped with a vascular clamp in order to close the system and allow pressurization with fluid by a needle puncture or a Luer lock connector or other ports  10 . 
     Aortic valve repair is performed using this method and a configuration of the device, which is shown in  FIG. 6 . As shown, the proximal open end  6  of chamber  5  is reversibly joined to the short open tube  1  by the connecting mechanism  2 , both adjoined by touching silicone or rubber washers  3 ,  4 , by mechanisms inclusive but not limited to the connecting mechanisms previously described. Inflow tubing  16  is joined to the tapered distal end  7  of chamber  5 , which may be transparent, contain a transparent window, or have one or more one-way valves or ports  20  for insertion of a video-scope or ultrasound probe, for example. Luer lock connector or port  10  and others not shown are used for removal of air, measuring chamber pressure, overflow valves as the chamber  5  and attached aortic root  18  are filled with clear fluid, i.e., crystalloid cardioplegia (substance used to maintain an arrested heart during surgery) provided by inflow tubing  16 . The short open tube  1  may be sutured to the aortic root  18  above the level of the valve, or to the ventriculo-aortic junction, as in aortic root replacement with aortic valve re-implantation. The aortic valve leaflets L and the left main coronary artery  19  are physically located proximal to the junction between the chamber  5  and the short open tube  1  and within the aortic root  18 , but can be visualized through the chamber  5  under conditions that simulate diastole (the period of time where the aortic valve is closed). If residual valve leaking is observed, the fixation tabs  8  and  9  may be grasped to facilitate separation of the transparent chamber  5  from the short open tube. Re-repair of the aortic valve is performed, and these steps are repeated until minimal aortic valve leaking is observed within the chamber under simulated diastolic conditions. 
     Once the repair is deemed to be satisfactory, the short open tube  1  may be transected or removed and the aorta closed. 
     Embodiments are envisioned wherein the device comprises a tube/cylinder comprised of fabric or other material that is sutured to the opened or transected aorta or ventriculo-aortic junction, and the aortic valve is accessed by making incisions in the tube/cylinder close to the point of attachment, and re-approximating those incisions in order to make valve re-assessments (to re-create a water-tight seal). One iteration of such device is illustrated in  FIG. 7 . The proximal end  6  of the device is sutured to the opened or transected aorta, or to the ventriculo-aortic junction (during aortic root replacement with aortic valve re-implantation). The distal end of tube/cylinder  5  may be closed, or open, but able to be clamped with a standard aortic vascular clamp  21 , while filling the tube or cylinder  5  with fluid by needle puncture, Luer lock connector or other port  10 . Other ports  10  may be used to monitor pressure or as relief valves. Port site  20  may comprise a one-way valve for insertion of a video-scope or ultrasound transducer  22 . In such a fashion, the valve may be indirectly visualized during simulated diastolic conditions by a video camera, for example. In some iterations, a transparent window is incorporated into the tube (not shown) to allow for direct visualization of the valve. The clamp  21  is removed and the valve can be repaired or re-repaired either through the open distal end of tube or cylinder  5 , or by making an incision in the fabric of the tube near the proximal end  6 . Such an incision could be re-sutured after valve repair is performed, so that a water-tight seal again may be achieved. Again, the tube/cylinder  5  is clamped  21  and diastolic conditions simulated by fluid filling the tube, possibly by a port  10 , and the repair evaluated by a video-scope  22 , for example, placed through port or one-way valve  20 . The process is repeated until a satisfactory result is obtained, and then the device is transected just beyond the proximal end  6 , which can be further sewn to the distal transected aorta to complete surgery. 
       FIGS. 8A-8F  show another embodiment of the device comprising a tube/cylinder  5  made of fabric (e.g., polyester) or other synthetic material. The tube/cylinder  5  is attached non-reversibly at its proximal end  6  to the aorta or to the ventriculo-aortic junction (as in aortic root replacement with aortic valve re-implantation. A feature of the tube/cylinder  5  is that it can be collapsed down to a much shorter length (i.e., less than 50% of its original length) in order to facilitate visualization and manipulation of the valve without the encumbrance of a bulky device. Tube or cylinder  5  ( FIG. 8A ) may be configured to roll down externally to achieve a partially roll down configuration  23  ( FIG. 8B ) or a fully collapsed  24  configuration ( FIG. 8C ). Another iteration of the device shows an accordion-type design ( FIG. 8D ) with corrugations that collapse down to a minimum and are held in place by temporary sutures  25  ( FIG. 8E ). The tube or cylinder  5  may comprise one or more Luer lock connectors  10  or other ports  20 , possibly comprising a one-way valve. In the unfurled or extended position, the distal end of tube or cylinder  5  can be clamped with an aortic vascular clamp (as in  FIG. 7 , clamp  21 , not shown in this figure) and diastole simulated. The valve can then be assessed either indirectly, by a video-scope or ultrasound placed via port  20 , or directly if tube/cylinder  5  is transparent or comprises a transparent window, as opposed to being made (partially or completely) from fabric. The clamp is removed, and the tube or cylinder  5  collapses down to a short length  24 , ideally less than 50% of its extended length ( FIG. 8F ). The valve leaflets L are visualized and manipulated and the process repeated until satisfactory. Not shown but intended is the possibility of incorporating a cinch mechanism into proximal end  6 . 
       FIGS. 9A-9E  show a general cinch mechanism that may be incorporated into the proximal end  6  of the short open tube  1 , shown axially in  FIGS. 9A-9C . At least one suture  26  is woven in and out of the circumference of the short open tube in a purse-string fashion. Polytetrafluoroethylene (PTFE) or other material pledgets  27  or a continuous strip of fabric or material  28  may be integrated or fused to the short open tube  1  and used to diminish bleeding points due to the passed suture  26 . In  FIG. 9C , the short open tube  1  is discontinuous (at arrow) yet still has integrated purse-string or strings  26 . Multiple purse-string sutures may be incorporated in order to asymmetrically narrow the purse-string if desired (not shown). When the purse-string suture is cinched or tied, the short open tube  1  is transformed into a structure of smaller diameter  28  ( FIG. 9E ), which may be a useful adjunct in aortic valve repair. A view from the side shows a typical pinched in appearance to short open tube  1  along suture line  26 . 
       FIGS. 10A-10C  illustrate a short cylinder  29  (transparent and closed on its distal end  31 , and open on its proximal end  32 ) or a transparent disc  33 , each comprising a reversible connecting mechanism  30  with the short open tube  1  by the connecting mechanism  35  associated with the aortic root  18 . The connecting mechanism  30  may comprise a groove or ridge, and when short cylinder  29  or disc  33  are placed within the short open tube  1 , a cinching mechanism  26  may be used to snare into the ridge or groove to reversibly fix the cylinder  29  or disc  33  within the short open tube  1 . Alternatively, the connecting mechanism  30  and the cinching mechanism  26  may instead comprise a magnet and a ferro-magnetic core to allow for reversible coupling, as previously described. Diastole is simulated by the Luer lock connector or other port  10 , and pressure regulation or overflow valve control may be incorporated  34 . The valve is inspected through the transparent surface  31  and then the cylinder  29  or disc  33  is separated from the short open tube  1 , which has been attached to the aortic root  18  either at the level of the transected aorta above the valve, or at the ventriculo-aortic junction (as in aortic root replacement with aortic valve re-implantation). Valve repair or re-repair is performed and the process repeated until a satisfactory result is obtained. The short open tube  1  is then sewn to the distal transected aorta to complete surgery. 
       FIG. 11  shows an embodiment of a transparent disc  33  that reversibly couples directly to a transected or opened aorta. A generally circumferential groove or ridge  30  is snared within the aorta  18  that has been opened distal to the valve leaflets L. Reversible coupling of the disc  33  to the aorta  18  is accomplished by external snaring  35 . The diastolic state of the aortic root  18  is simulated by infusion of clear fluid via port  10 , provided by tubing  16 . Surface  31  is partially or completely transparent, or may comprise a magnification or distortion lens. 
       FIG. 12  shows another embodiment of the mechanism for reversible coupling of transparent cylinder  5 . In this iteration, proximal open end  6  comprises a generally circumferential ridge or groove  30  that can be reversibly attached to the aorta  18  or a short open tube (not shown) via an external snare  35 . Groove or ridge  30  is placed inside of aorta  18  and external snare  35  is outside of aorta  18  (or short open tube, not shown), and keeps the entire chamber  5  firmly in place, and in a generally water-tight configuration. Fluid for pressurization of the aortic root is infused via distal end  7 , and pressure can be monitored via port  10 . 
     Having thus described several aspects of at least one embodiment of this disclosure, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the disclosure. Accordingly, the foregoing description and drawings are by way of example only.