Patent Application
20160206798
The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.
This disclosure relates generally to endovascular aortic occlusion devices deployed within the aorta. More particularly, the invention relates to endovascular aortic occlusion devices adapted for augmenting blood pressure and controlling blood flow downstream of the occluded region.
Death from the complications of truncal hemorrhage continues to exist as a high probability in an overwhelming number of cases in both the military and civilian medical spheres. Existing systems and procedures used to control truncal hemorrhage frequently contribute to a patient's ultimate death through inability to maintain adequate blood flow to vital organs. It is well recognized that without controlled distal reperfusion, hemodynamic collapse is common, particularly where open aortic cross-clamping is used to stop hemorrhage. The ability to rapidly deliver effective, variable and adaptive control of aortic flow for hemorrhaging patients will save innumerable lives.
Mitigation of battlefield injury and hemorrhage is a high priority of U.S. military trauma surgeons and researchers. Uncontrolled blood loss is recognized as the leading cause of death in 90 percent of the potentially survivable battlefield cases and in 80 percent of those who died in a military treatment facility. “Bleed-outs,” especially those caused by groin or neck wounds, challenge medics, corpsmen and physicians who can do little to stop blood loss caused by major arterial injuries.
Two devices, the Combat Ready Clamp and Abdominal Aortic Tourniquet, have been built to treat truncal injuries. The Combat Ready Clamp is primarily for treating junctional hemorrhage (i.e. between the trunk and an extremity). The Combat Ready Clamp is ineffective against wounds involving the genital region or the loss of both legs. The Abdominal Aortic Tourniquet functions as a large blood pressure cuff which wraps around the lower torso to minimize extremity bleeding.
Limiting or stopping blood flow through the major blood vessel of the body, the aorta, is an established method for slowing the rate of blood loss in a severely injured patient with ongoing bleeding. In the military, this aortic occlusion has traditionally been achieved using a large aortic clamp inserted into the chest cavity via a large incision between the ribs. This dramatic and extremely invasive maneuver is typically a “last ditch” effort. The clamping of the aorta excludes the systemic circulation, by definition, thus causing an ischemia. The goal of the aortic clamping procedure is to keep the patient's remaining blood circulating to the heart, lungs, and brain for precious minutes until bleeding below the aortic clamp is controlled and the patient can be resuscitated and systemic circulation restored. Because of the inherent morbidity of the aortic clamp maneuver, it is often reserved for only the sickest or moribund patients who have lost vital signs and are essentially already dead.
Recently, balloon catheters used in endovascular surgery have been repurposed to fully occlude the aorta by inflation of a balloon in the lumen of the aorta, as an alternative to aortic clamping. This procedure is referred to as Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA). REBOA has the potential to achieve effective aortic occlusion with less morbidity. Therefore, REBOA may be used earlier in the clinical course of the bleeding patient.
As with aortic clamping, REBOA can be used to increase blood pressure to vital organs while slowing ongoing blood loss. However, currently available FDA-approved balloon catheters used for REBOA can only reliably achieve complete occlusion or no occlusion. As such, attempting to wean a patient from complete balloon occlusion by slowly deflating the balloon is not achievable. When aortic occlusion is used in the course of treatment of a hemorrhaging patient, the physician must begin to wean the patient off complete occlusion as early as possible. Using REBOA, when the balloon is inflated, everything below the balloon quickly starts to die due to lack of blood flow. When the balloon is deflated to initiate flow, hemodynamic collapse is a possibility. Additionally, variation in patient size (height, weight, aortic diameter) limits the ability of a single REBOA catheter to effectively occlude aortic flow in all patients.
Currently, REBOA is performed utilizing devices largely intended for other purposes, specifically the FDA-approved CODA® balloon catheter (Cook Medical Technologies, LLC, Bloomington, Ind.) for occluding large blood vessels and molding of aortic endoprostheses. While effective at complete aortic occlusion, the CODA® balloon catheter is not ideally suited for partial vessel occlusion or controlled distal reperfusion during gradual deflation based on its inherent design characteristics, particularly an inability to create a variable and sustained pressure gradient across the balloon. An example of this type of device is disclosed by Eliason et al., U.S. Patent Application Publication No. 2013/0102926, published Apr. 25, 2013, which is incorporated by reference herein in its entirety. The invention of Eliason et al. is directed to a method for placing an aortic occlusion device without having to rely on fluoroscopy to ensure proper placement. The system of Eliason et al. relies on the use of an inflatable balloon to provide occlusion, and thus, has only marginal ability to control variability in flow from upstream to downstream of the occlusion device. Moreover, the system of Eliason et al. is unable to provide controlled anterograde blood flow (i.e., distal reperfusion).
It is well recognized that without controlled distal reperfusion, hemodynamic collapse is common. In particular, hemodynamic collapse has a high probability of occurrence when open aortic cross-clamping is used to staunch blood flow. Although complete occlusion can stop distal blood loss, complete occlusion also causes supraphysiologic blood pressure spikes to everything upstream of the occlusion balloon. These blood pressure spikes can worsen concomitant injuries to tissue beds proximal to the balloon (e.g. traumatic brain injury, pulmonary contusions and hemorrhage, or traumatic amputations of the upper extremities). Additionally, upon uncontrolled release of complete occlusion, the blood volume supplying the heart, lungs and brain is rapidly redistributed to the lower half of the body effectively reducing the circulating blood volume. Additionally, peripheral vasodilation and the washout of toxic metabolites, which have built up in the ischemic tissues, can result in myocardial suppression and further deterioration of hemodynamics. As a result, the growing clinical experience with REBOA in its current form reveals negative physiologic effects.
The current compliant balloon architecture poses technical challenges for incremental restoration of distal reperfusion necessary to prevent hemodynamic collapse following complete aortic occlusion. As an alternative to compliant balloon architectures, there exist fixed-diameter, non-compliant balloon catheter designs (e.g., ARMADA® by Abbott Laboratories Corp., North Chicago, Ill.). However, these catheters are intended and approved for vessel dilation (angioplasty), typically for narrowed vessels (e.g., atherosclerosis). Additionally, a fixed-diameter, non-compliant balloon catheter must be sized appropriately to properly occlude each patient's aorta. Consequently, although the non-compliant balloon is less susceptible to change in shape due to blood pressure spikes, the inability to change diameter outside of a narrow range impedes its ability to serve as an adaptable device to support both complete occlusion and partial occlusion. Therefore, the relatively fixed diameter of non-compliant balloon catheters limits their real-world applicability across a range of normal aortic diameters.
Other efforts have been directed to development of potential alternative methods of providing aortic occlusion. For example, Barbut et al., U.S. Pat. No. 6,743,196, issued Jun. 1, 2004, describes a plurality of approaches to support aortic occlusion. Each approach described in Barbut et al. includes a catheter having a distally mounted constricting mechanism. Each constrictor is collapsed to facilitate insertion and then expanded once inserted to obstruct blood flow. Barbut et al. describes a constrictor comprising an outer conical shell and an inner conical shell, each having a distal open base and proximal apex. The outer shell further includes a pre-shaped ring to facilitate expansion. Both shells include ports or openings. Flow through the mechanism is controlled by rotating the inner conical shell such that the ports of each shell communicate.
More recently, VanCamp et al, in U.S. Pat. No. 7,927,346, issued Apr. 19, 2011, describes a device to provide temporary partial aortic occlusion to achieve diversion of blood flow to the brain in patients suffering from cerebral ischemia. The primary thrust of the VanCamp et al. invention is the provision of an occlusion device that does not require fluoroscopy to ensure proper placement. VanCamp's device includes an expandable frame with a planar membrane mounted on a first portion of the frame to occlude blood flow. In one embodiment disclosed in VanCamp et al., the membrane includes a fixed size opening in the center of the planar membrane to allow some blood to flow through the opening. Alternatively, VanCamp also discloses that the membrane itself may be somewhat permeable to blood flow to allow some flow. However, VanCamp is unable to provide variable control of blood flow during use.
In light of the aforementioned considerations and limitations of existing and proposed devices, there exists an urgent and unmet need for a viable solution to allow a physician to address hemorrhagic injuries and carefully regulate blood flow, from complete occlusion to sustained partial occlusion, with an ability to adjust the level of occlusion as the patient's vital signs dictate.
The present invention, in its several embodiments, comprises a medical device to control blood flow and pressure in a patient having hemorrhagic blood loss from a traumatic truncal wound, hereinafter the endovascular variable aortic control catheter (“EVACC”) or “EVAC device”. The various embodiments of the EVACC enable adaptable and variable aortic occlusion for controlling anterograde blood flow and augmenting blood pressure to vital organs, particularly in patients suffering from significant blood loss. A relevant example is a patient presenting with a traumatic hemorrhagic event, such as a gunshot wound to the abdomen. The EVAC device provides variable levels of aortic occlusion to control distal aortic blood flow and pressure on either side of an occlusion barrier established by the device.
As used herein, the terms “proximal” and “distal” are from the perspective of the physician or other medical professionals, such that “proximal” describes a direction away from a patient, while “distal” describes a direction toward the patient. For example, the end of a device that is inserted into a patient would be considered the “distal end”; the end held by the physician would be considered the “proximal end”.
Further, as used herein, the terms “upstream” and “downstream” describe portions of the vascular system located on either side of the occlusion barrier. “Upstream” is in a direction away from the occlusion barrier toward the heart and associated vascularity; and “downstream” is away from the occlusion barrier to the remaining vascularity, i.e., systemic circulation, in communication with the site of hemorrhage.
Each of the various embodiments described herein is able to achieve more precise regulation of the degree of aortic occlusion and controlled incremental restoration of downstream reperfusion. Accordingly, one object of the various embodiments of the invention is to quickly staunch a source of bleeding. Another object is to reinitiate blood flow to deprived areas of the body while maintaining adequate flow and pressure in the vascularity serving the brain, lungs and other critical organs.
A further object of the various embodiments of the invention is to allow a physician to safely transition a patient from a state of complete aortic occlusion to a plurality of levels of partial aortic flow and back and forth between complete occlusion and a plurality of levels of partial flow. The invention will allow a physician to wean a patient between various states of partial aortic flow to promote a more effective process for promptly responding to the patient's varying physiologic and vascular conditions.
Yet another object of the various embodiments of the invention is to allow a physician to wean a patient dynamically in real-time to respond to a patient's changing physiologic conditions. A further object of the various embodiments of the invention is to allow controlled distal reperfusion as required to minimize the likelihood of reperfusion injury associated with tissue ischemia associated with aortic occlusion. Another object of the various embodiments of the invention is to support patients suffering from other non-hemorrhagic causes of shock including, but not limited to, sepsis, cardiogenic shock, and spinal shock.
Not all of the objects described above need be accomplished in aggregate by any one or more of the various embodiments of the invention. Each of the objects may be accomplished individually or in combination with other objects by any one of the embodiments according to the invention. Consequently, interpretation of the claims herein should not be limited by any one or more of the objects addressed above.
Thus, in accordance with embodiments of the present invention, an endovascular variable aortic occlusion device is provided that comprises a central guide wire; a distal end potion that includes a first wire framework and an occlusion barrier; a delivery sheath, and a proximal end portion that includes a hand piece having a stationary portion and a movable portion. The first wire framework of the distal end portion is radially expandable and collapsible. The wire framework is configured to radially expand to a sufficient radial circumference to engage with an aortic wall within a lumen of an aorta to secure the device within the aorta. The occlusion barrier surrounds at least a portion of the first wire framework and is attached thereto to provide a cup-shaped occlusion barrier, such that an upper perimeter of the occlusion barrier contacts the aortic wall when the wire framework is radially expanded. The occlusion barrier also includes at least one adjustable passageway therein to facilitate controlled anterograde blood flow. The delivery sheath is extensible and retractable, wherein a collapsed form of the first wire framework is contained therein during delivery of the device into the lumen of the aorta. The movable portion of the hand piece controls a translational movement of the delivery sheath relative to the wire framework to enable unsheathing and radial expansion of the first wire framework. The movable portion of the hand piece may also be configured to adjust the at least one adjustable passageway to regulate controlled anterograde blood flow.
Each of the various embodiments described herein have common elements that support the delivery of an effective occlusion barrier, but each of the embodiments has slightly different movable elements for controlling the adjustable passageway to regulate controlled anterograde blood flow. As appropriate, additional detail associated with each of the described embodiments will focus on the specific movable structural elements that provide control of anterograde (or downstream) blood flow rather than the common elements. Following is a listing of the various embodiments of the invention described herein, named in reference to their movable structural elements that enable flow control: 1) Fenestrated cylindrical conduit (“FCC”); 2) Single aperture reduction (“SAR”); 3) Captive balloon (“CB”); 4) Fenestrated cone (“FC”); 5) Peripheral internal constriction (“PIC”); 6) Lasso aperture closure (“LAC”); 7) Rotating cup (“RC”); and 8) Deformable cup (“DC”).
In a first embodiment, identified herein as a Fenestrated Cylindrical Conduit (FCC), the EVACC-FCC comprises a catheter-based system having a proximal hand piece for controlled deployment and operation of a distal portion of the device, wherein the distal portion is used to both partially and completely occlude the aorta. The distal portion of the EVACC-FCC comprises the components necessary to create an occlusion barrier within a targeted blood vessel, e.g., the aorta. In this first embodiment, a cylindrical conduit having a plurality of orifices (i.e., a fenestrated cylindrical conduit) extends proximally from a bottom of the occlusion barrier. Regulation of anterograde blood flow is achieved by translational movement of the delivery sheath relative to the occlusion barrier to change a number of orifices in an uncovered state to adjust an available flow area for blood flow. In one aspect, the occlusion barrier may comprise an expandable and collapsible impermeable membrane that is supported by an expandable and collapsible egg-shaped memory wire architecture. When deployed to occlude a blood vessel, the memory wire architecture expands the impermeable membrane to form a cup-shaped occlusion barrier. The conduit and the occlusion barrier may be formed as a unitary body or may be discreet components joined together (e.g., by glue, thermal fusion, or a mechanical mating arrangement, for example).
The collapsible membrane and associated memory wire architecture are deployed into a vessel through a delivery sheath. During use, when deployed out the end of the delivery sheath, the memory wire architecture and an upper perimeter of the cup of the collapsible membrane expand to the size of the lumen of the blood vessel, e.g., the aorta, creating a barrier or restriction to flow. The cup-shaped occlusion barrier funnels flow into the cylindrical fenestrated conduit. The fenestrated conduit has a plurality of orifices or perforations that can be exposed or covered to support variable downstream flow to systemic circulation. Linear translation of the delivery sheath causes the orifices in the fenestrated conduit to be exposed or covered. Thus, the EVACC-FCC is able to control the rate of blood flow through the orifices or fenestrations below the occlusion barrier as well as the blood pressure on either side of the occlusion barrier. Once the occlusion barrier is fully deployed within the aorta, the delivery sheath may be retracted in a controlled and graded fashion to uncover one or more orifices in the fenestrated conduit, thereby allowing blood to flow from a higher-pressure upstream vascular region to a lower pressure downstream systemic vascular region.
In a second embodiment of the invention, identified herein as a Singled Aperture Reduction (SAR), the movable elements for controlling the adjustable passageway to regulate controlled anterograde blood flow is based on aperture reduction and/or enlargement via linear translation of the delivery sheath over a neck of the wire basket architecture. From its top perimeter, the cup of the occlusion barrier narrows to a single circular aperture whose size is variably adjusted by the advancement or retraction of the delivery sheath toward or away from the aperture. As the delivery sheath is moved towards the aperture, the wires of the supporting wire basket architecture are drawn close together to converge, and the diameter of the aperture is likewise reduced, restricting flow through the aperture and reducing downstream systemic circulation. To increase flow, the delivery sheath is moved away from the aperture, enlarging the aperture and hence, the flow area.
In a third embodiment, identified herein as Captive Balloon (CB), the movable elements for controlling the adjustable passageway to regulate controlled anterograde blood flow include an inflatable obstructive member (e.g., a captive balloon) extending into a single circular orifice, where inflation or deflation of the inflatable obstructive member adjusts a diameter of the portion of the inflatable obstructive member extending into the orifice to change an available flow area for anterograde blood flow. In one aspect, the single orifice may extend into an impermeable cylindrical conduit, such that the captive balloon is within the conduit. Rather than tapering down to a fenestrated conduit, the impermeable cylindrical conduit is internally occupied by a corresponding cylindrical balloon. The cylindrical conduit may have limited expansion. The balloon may be inflated to varying degrees within the conduit to variably occlude the lumen of the conduit, thus increasing resistance to flow and flow restriction. Complete occlusion is accomplished by full inflation of the balloon within the cylindrical conduit.
In a fourth embodiment, identified herein as Fenestrated Cone (FC), the movable elements for controlling the adjustable passageway to regulate controlled anterograde blood flow include a conical conduit having a plurality of orifices (i.e., a fenestrated cone) extends proximally from a bottom of the occlusion barrier. Regulation of anterograde blood flow is achieved by translational movement of the delivery sheath relative to the occlusion barrier to change a number of orifices in an uncovered state to adjust an available flow area for blood flow. The proximal region of the cup of the occlusion barrier tapers to a conically-shaped fenestrated conduit, rather than the cylindrical fenestrated conduit described above. As with the first embodiment, retraction or deployment of the conical portion out of the sheath regulates flow by causing the fenestrations to be covered or exposed and the diameter of the conical portion to be reduced as the sheath is linearly translated to cover more of the conically-shaped conduit.
In a fifth embodiment, identified herein as Peripheral Internal Constriction (PIC), movable elements for controlling the adjustable passageway to regulate controlled anterograde blood flow include a conduit portion comprising an elastomeric wall that extends proximally from the occlusion barrier; and a wire mesh structure comprising a cylindrical, helically-wound braid that is surrounded by the elastomeric wall of the conduit portion. This configuration is akin to a “finger trap” design. The proximal region of the cup of the occlusion barrier tapers to this conduit portion, whose interior incorporates a wire mesh structure (e.g., a helically-wound braid) anchored to a central structural wire. The proximal portion of this conduit portion is open to allow downstream flow. The wire mesh structure or architecture may be constructed of a shape memory material, such that in its native state, the conduit portion is open. Retraction on the cylindrical conduit portion results in elongation and diameter reduction, but does not disrupt the upper perimeter of the occlusion barrier's apposition to the aortic wall. Instead, mechanical retraction of the conduit pulls against a point of fixation on a central structural wire. By elongating and narrowing the conduit portion, flow through the device is variably restricted.
In a sixth embodiment, identified herein as lasso aperture closure (LAC), the movable elements for controlling the adjustable passageway to regulate controlled anterograde blood flow include a lasso aperture constriction. The proximal region of the cup-shaped occlusion barrier narrows to an aperture or orifice that is variably restricted in diameter by the retraction of wires. In one embodiment, a lasso wire is provided that includes a distal end wire segment configured in a semi-circle having two end portions, and a wire portion extending from each end portion and terminating at the movable portion of the hand piece. The first wire framework passes through the semicircle of the distal end wire segment. An overlapping portion extending from the proximal terminal end of the occlusion barrier conforms to the distal end wire segment and thereby forms a single circular orifice at the proximal terminal end of the occlusion barrier. Retraction (or possibly rotation) of the wire portions extending from the end portions controls the size of the orifice. This function is similar to closing of a noose in a lasso.
In a seventh embodiment, identified herein as rotating cup (RC), movable elements for controlling the adjustable passageway to regulate controlled anterograde blood flow include two cup-shaped membranes where a first cup-shaped membrane has a first set of openings and a second cup-shaped membrane has a second set of openings. The adjustable passageway is formed by rotational alignment of the first and second set of openings to coincide, where at least one of the first or the second cup-shaped membrane is coupled to the movable portion of the hand piece. A rotational motion of the movable portion of the hand piece causes a relative rotation between the first and the second cup-shaped membrane to vary a degree of coincidence between the first and second set of openings. In one embodiment, the second (downstream) cup membrane includes a set of openings (e.g., two slots) to allow flow when the openings are uncovered, and is supported by the first wire framework. The first (upstream) cup membrane also includes a set of openings, and is supported by a second wire framework and may be rotated in either direction to cover or uncover the openings in the second cup membrane to restrict or increase blood flow, respectively.
In an eighth embodiment, identified herein as deformable cup (DC), the movable elements for controlling the adjustable passageway to regulate controlled anterograde blood flow include two mating cup-shaped membranes, where an inner cup is deformable. The occlusion barrier includes a first cup-shaped membrane bonded to the first wire framework, where interstitial openings are present around a perimeter of the first cup-shaped membrane; and a second cup-shaped membrane positioned upstream relative to the first cup-shaped membrane. The second cup-shaped membrane includes a central aperture in a bottom portion, and the second cup-shaped membrane conforms to a distal surface of the first cup-shaped membrane, and wherein the central aperture in the second cup and the interstitial openings in the first cup do not coincide when mated together. In one aspect, the two mating cups may be supported by a single wire basket architecture. The second cup-shaped membrane may include a flexible impermeable membrane having a central aperture. The aperture may be linearly reciprocated back and forth, creating various toroidal shapes and uncovering or covering the interstitial openings within the downstream cup. In a fully closed state, the second (upstream) cup-shaped membrane adapts to the shape of the first (downstream) cup-shaped membrane, such that the interstitial openings are fully covered by the upstream membrane and flow is occluded. Flow is increased by linear translation of a center wire to lift the center aperture, and a portion of the surrounding circumferential area, of the upstream membrane off the downstream occluding element, causing the interstitial openings between the petals of the first occluding element to be uncovered, thereby allowing flow to occur.
These and other features, aspects and advantages of various embodiments of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:
The accompanying drawings numbered herein are given by way of illustration only and are not intended to be limitative to any extent. Commonly used reference numbers identify the same or equivalent parts of the claimed invention throughout the accompanying drawings.
Following is a listing of the various embodiments of the endovascular variable aortic control catheter (hereinafter, “EVACC”) described herein, named in reference to movable elements used to control, regulate, and/or modulate anterograde blood flow and identified by their shortened acronym and associated reference numeral. Hereinafter, each of the various embodiments of the EVACC will be identified by the precursor, “EVACC”, followed by additional initials describing the movable elements that enable anterograde blood flow control, e.g., “FCC” for “fenestrated cylindrical conduit”, and then the appropriate reference numeral, e.g., “10”.
1. Fenestrated Cylindrical Conduit (EVACC-FCC 10);
2. Single Aperture Reduction (EVACC-SAR 100);
3. Captive Balloon (EVACC-CB 200);
4. Fenestrated Cone (EVACC-FC 300);
5. Peripheral Internal Constriction (EVACC-PIC 400);
6. Lasso Aperture Closure (EVACC-LAC 500);
7. Rotating Cup (EVACC-RC 600); and
8. Deformable Cup (EVACC-DC 700).
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The EVACC-FCC 10 comprises a central guide wire 20, a supporting memory wire basket architecture 30, an occlusion barrier 40, a flow-regulating fenestrated cylindrical conduit 50 and an extensible and retractable delivery sheath 60. As indicated by segmentation symbol 62, the length of the delivery sheath 60 and central guide wire 20 may be varied to accommodate differing deployment requirements.
An exemplary version of a hand piece 70 used to manipulate and control the distal components of the EVACC-FCC 10 is shown. This same hand piece 70 may be used to manipulate the distal components of the additional embodiments described herein. The hand piece 70 comprises a stationary distal grip 71 and a rotatable proximal grip 72. Proximal grip 72 is rotatable on threaded guide 74 to manipulate the distal components of the EVACC-FCC 10 during and after deployment. Additional wire assemblies (not shown) may be threaded through a center lumen (not shown) of the threaded guide 74 to provide additional methods for actuating the distal components.
Now, in greater detail,
The wire basket architecture 30 may be made of nitinol or other material having similar memory-shape properties. As illustrated, the wire basket architecture 30 assumes an approximate egg-shape when fully deployed and released from the delivery sheath 60. It should be appreciated that other shapes, e.g., spherical or cylindrical, are further contemplated. The wire basket architecture 30 expands when deployed out the end of the delivery sheath 60 and will collapse upon retraction back into the delivery sheath 60. The wire basket architecture 30 and its neck 32 are partially enveloped by and provide structural integrity to both the occlusion barrier 40 and a fenestrated cylindrical conduit 50, while ensuring adequate but not excessive apposition of the occlusion barrier 40 to the aortic wall.
The occlusion barrier 40 comprises a membrane, preferably made of expanded polytetrafluoroethylene (hereinafter, “ePTFE”). Other materials, such as polyester, may also be used to form the occlusion barrier 40. When deployed, the occlusion barrier 40 expands to form a cup 42 having an upper perimeter edge 44. The cup 42 necks down to the fenestrated cylindrical conduit 50.
The fenestrated cylindrical conduit 50 includes a plurality of orifices or perforations 52 distributed along its length through which blood may flow when not covered by the delivery sheath 60. When complete occlusion of flow is desirable, the perforations 52 are covered by the delivery sheath 60. The perforations 52 may be uncovered and opened to varying degrees by linear retraction of the delivery sheath 60 from over the perforations 52, thereby allowing blood flow and pressure to be altered. Similar to the occlusion barrier 40, the fenestrated cylindrical conduit 50 is preferably made of ePTFE, but may be made of other materials to increase rigidity or elasticity during deployment. In one aspect, the occlusion barrier 40 comprising the cup 42 and fenestrated conduit 50 form one unitary piece. In another aspect, the occlusion barrier 40 may comprise a separate cup 42 and fenestrated conduit 50, which are joined or bonded by various means, such as glue, thermal fusion or a mechanical mating arrangement.
The EVACC-FCC 10 may be constructed using standard, commercial-grade endovascular components. The delivery sheath 60 is preferably deployed through a percutaneous introducer catheter directly into the femoral artery. The delivery sheath 60 is then advanced to the level of the thoracic or abdominal aorta and then the basket architecture 30 and occlusion barrier 40 are deployed.
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The delivery sheath 60 of the EVACC-FCC 10 is preferably inserted into the arterial tree through a 7-French sheath or smaller. The degree to which the fenestrated cylindrical conduit 50 is opened to allow flow is controlled by the hand piece 70 connected to a proximal portion of the EVACC-FCC 10 (outside the patient). During initial insertion into the arterial tree and through advancement to the desired occlusion site within the aorta A, the central guide wire 20, the wire basket architecture 30, the collapsible occlusion barrier 40 and the fenestrated cylindrical conduit 50 are initially enclosed in the delivery sheath 60, in a manner similar to vena cava filter deployment catheters. Once deployed out the delivery sheath 60 and into the lumen of the aorta A, the wire basket architecture 30 will assume its natural opened position and appose the wall of the aorta, thereby creating a sealing portion buttressed by the unfurling of the occlusion barrier 40. The degree of occlusion and flow control may be manipulated by covering and exposing the perforations 52 of the fenestrated cylindrical conduit 50 via advancement and retraction of the delivery sheath 60. The advancement and retraction of the delivery sheath 60 may be accomplished by rotary manipulation of the rotatable grip 72 of hand piece 70 to advance a threaded guide 74 in either a proximal or a distal direction. The stationary distal grip 71 and rotatable proximate grip 72 of the hand piece 70 are rotated in opposite directions to linearly translate the threaded guide 74, which is attached via pull wires to the sheath 60 and/or the fenestrated cylindrical conduit 50.
The EVACC-FCC 10 and the additional embodiments described herein may be equipped with blood pressure measuring capabilities proximal and distal to the occlusion barrier 40 for measuring upstream and downstream blood pressure. The blood pressure measuring capabilities may comprise a manometer mounted on the EVACC-FCC 10 or a channel communicating with a transducer at the proximal end and a port at the distal end of the EVACC 10. Blood pressure measuring may also be accomplished by use of a fiber optic in vivo pressure transducer as described in U.S. Pat. Nos. 5,392,117 and 5,202,939, each of which is incorporated herein by reference in its entirety, or a Radi pressure wire as described in U.S. Pat. Nos. Re 35,648; 5,085,223; 4,712,566; 4,941,473; 4,744,863; 4,853,669; and 4,996,082, each of which is incorporated herein by reference in its entirety.
With the inclusion of upstream and downstream pressure sensors, upstream and downstream blood pressure measurements may then be recorded and displayed via a monitor at a proximal end of the EVACC-FCC 10, A control device or module (not shown) may be programmed with various preferred treatment and operational parameters. The control device may then provide automated control of the operational parameters including: 1) blood pressure, upstream and downstream of the occlusion barrier 40, and 2) flow diversion through the uncovered perforations 52 of the fenestrated conduit 50. For example. the control device can include a set pressure threshold to maintain upstream blood pressure to a desired level.
Data communicated to the pressure monitor from pressure sensors may be transferred or transmitted to the control device, which then sends control signals to a separate electrically-powered rotary unit to linearly translate the threaded guide 74 and the delivery sheath 60. The translational movement of the delivery sheath 60 by the threaded guide 74 controls exposure of perforations 52 in the fenestrated cylindrical conduit 50. The threaded guide 74 retracts or extends the delivery sheath 60 to uncover or cover the perforations 52, thereby adjusting the diversion of flow from upstream to downstream and causing modification of blood pressure on each side of the occlusion barrier 40.
In the field, where a separate automated control device may not be available, the hand piece 70 can be manually rotated to obtain desired upstream and downstream blood pressures. An audible alarm may be incorporated into the pressure monitor to sound when blood pressures exceeds desired thresholds. In one aspect, the rotary unit, pressure monitor, and control device may be integrated into the hand piece 70 of the EVACC 10.
The EVACC-FCC 10, and the additional embodiments described herein, are configurable to provide adaptive control of the means for flow regulation. Adaptive control is described in the context of the EVACC-FCC 10, but is intended to extend to the functionality of the additional embodiments described herein. In each embodiment, adaptive control is accomplished via manipulation of the various movable elements used for anterograde blood flow control.
Hence, in the case of the EVACC-FCC 10, adaptive control may be accomplished via the exposure or covering of the perforations 52 based on continuous dual pressure measurements both upstream and downstream of the occlusion barrier 40. Estimates of systemic flow may be determined via algorithms correlated to each EVACC-FCC 10 based on the pressure measurements. The real-time availability of both flow measurments and pressure measurements may then be used to inform either physician decisions or automated adaptive control of the EVACC-FCC 10 according to specified operational parameters. For example, just as a tourniquet is periodically released to allow flow to avoid further tissue damage, the EVACC-FCC 10 may operate via the automated control device to periodically adjust flow downstream of the occlusion barrier 40 to avoid ischemia, or, to reduce downstream flow to divert flow to the brain and other vital organs upstream of the occlusion barrier 40.
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The delivery sheath 60 may be advanced or retracted over the fenestrated cylindrical conduit 50 to continually adjust flow from fully occluded to various levels of partial occlusion. This ability to continually redistribute flow as required by a patient's physiologic status allows a surgeon to maximize the probability of survival and minimize potential negative outcomes, such as hemodyamic collapse, when weaning the patient off full or partial occlusion.
Now, several alternative embodiments are described in detail in the following paragraphs. In each alternative embodiment, the device is deployed and used in a similar fashion as described for the EVACC-FCC 10. However, in each alternative embodiment, the structure, configuration and operation of movable elements used for flow control will differ to varying degrees.
Single Aperture Reduction Embodiment (EVACC-SAR 100):
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Fenestrated Cone Embodiment (EVACC-FC 300):
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Referring now to FIG., 20, a perspective view of the occluding portion of the EVACC-FC 300 is illustrated, looking into the interior of the cup 342 of the occlusion barrier 340 and revealing the perforations 352. The occlusion barrier includes a cup-shaped diverter 342 having an upper perimeter 344.
In
Peripheral Internal Constriction Embodiment (EVACC-PIC 400):
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In a fully deployed state, the EVACC-PIC 400 is actuated by the retraction or extension of an inner pull wire 456 that causes the PIC wire structure 450 to extend and reduce its diameter, or, shorten and expand its diameter. The proximal orifice 454 will increase or decrease in size as well, in correlation to the lengthening or shortening of the PIC wire structure 450. The individual wires of the PIC wire structure are threaded together in a manner similar to a finger trap toy, wherein extending the PIC wire structure causes the individual wires to rotate and mesh more closely together, thereby increasing resistance to flow caused by the restriction within the extended neck 446. Thus, upstream and downstream blood pressure and flow through the EVACC-PIC 400 may be adjusted and controlled. The material used to form the extended neck 446 will have sufficient elasticity to stretch and narrow in correlation with the PIC wire structure 450.
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Deformable Cup Embodiment (EVACC-DC 700):
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Although not specifically shown, applicable to several embodiments described herein, the EVACC may include one or more pressure sensors that communicate blood pressure measurements to an external display, an external control device, or both. The display provides pressure readings to the surgeon to inform the surgeon's operational decisions. Alternatively, the pressure data may be processed by the external control device, and then used by the control device to determine a desired level of flow restriction. For example, the control device can operate a rotary unit, such as a small stepper motor, to operate the central threaded guide, which may be configured to a) linearly translate the sheath back and forth over perforations in a fenestrated conduit, b) linearly translate a tension wire to constrict or expand a lasso, or c) pressurize or depressurize a captive balloon, for example. Additionally, the EVACC may also incorporate and provide automated control of the degree of flow restriction via an active control algorithm that determines adjustments based on the patient's physiologic status as determined by blood pressure, other relevant metrics and the assessment of the surgeon. A visual display and associated operational dashboard provides an active touch interface for use by the surgeon or a surgeon's assistant to actively control the operation of the EVACC once deployed. Where an automated control system is provided, the display provides relevant operational parameters and allows automated control to be overridden by the surgeon or assistant. The display may include icons that are selectable by touch, keyboard, mouse, voice or gesture. The interactive features will allow the surgeon or assistant to quickly select various desired flow and pressure conditions to achieve certain physiologic objectives and set desired operating parameters.
Although driven by a need to address treatment of soldiers injured on the battlefield, the EVACC, in its several embodiments described herein, has applicability that extends beyond military and civilian trauma victims. Any patient with significant risk of hemorrhage will benefit from use of the EVACC to support regulation of distal aortic flow to augment vital perfusion to critical organs. In addition, patients that require increased diversion of blood flow to other portions of their body, such as the brain, can use the device, initially deployed to allow full flow, to gradually restrict downstream flow, and increase flow and pressure to those targeted areas. This approach for augmenting central aortic pressure to perfuse the heart, lungs and brain would extend beyond hemorrhagic shock to include any patient with hypotension and shock that needed augmentation of pressure to keep vital organs alive while other therapeutic measures were undertaken or to support physiology during transport to definitive care.
In addition, although shown and described herein as applicable to use in human subjects, the EVACC is likewise adaptable to use in animal subjects.
The present invention has been particularly shown and described with respect to certain preferred embodiments and features thereof. However, it should be readily apparent to those of ordinary skill in the art that various changes and modifications in form and detail may be made without departing from the spirit and scope of the inventions as set forth herein and the appended claims.
The present application claims priority to U.S. Provisional Patent Application Serial Nos. 62/105,887 filed Jan. 21, 2015, and 62/235,087 filed Sep. 30, 2015, each of which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62105887 | Jan 2015 | US | |
| 62235087 | Sep 2015 | US |
