WO2025038641A2

WO2025038641A2 - Stabilized intravascular cannula

Info

Publication number: WO2025038641A2
Application number: PCT/US2024/042119
Authority: WO
Inventors: Peyman Benharash; Joseph HADAYA; Yas SANAIHA; Ali NSAIR
Original assignee: The Regents Of The University Of California
Priority date: 2023-08-14
Filing date: 2024-08-13
Publication date: 2025-02-20

Abstract

A cannula includes a cannula body having a first proximal opening, a first distal opening and a first lumen extending therebetween, and a second proximal opening, a second distal opening, and a second lumen extending therebetween. The second distal opening is configured distal of the first distal opening. A retractable stabilization element is configured between the first and second distal opening, the retractable stabilization element configured to define a plurality of voids therethrough when in an expanded state within a vessel. Alternate cannula embodiments are also described.

Description

STABILIZED INTRAVASCULAR CANNULA

CROSS REFERENCE TO RELATED APPLICATIONS

[1 ] This application claims priority to U.S. Provisional Application No. 63/519,309 filed August 14, 2023, which is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

[2] Extracorporeal life support modalities (referred to in aggregate as ECLS) have grown by over 900% in the United States over the last 10 years. These technologies provide temporary cardiac, pulmonary, or cardiopulmonary support for patients with cardiac or pulmonary failure, allowing clinicians to sustain life while the underlying cause is treated, or while organ transplantation is pursued. These modalities have been broadly applied worldwide for acute or chronic respiratory failure, cardiogenic shock (including shock secondary to myocardial infarction or pulmonary embolism), postcardiotomy syndrome, and in those experiencing cardiac arrest.

[3] Support modalities may support solely the lungs, the lungs and right heart, or both the heart and lungs, depending on cannula and circuit configuration. For example, venoarterial extracorporeal membrane oxygenation (ECMO) provides cardiac and pulmonary support by draining blood from the venous circulation, performing gas exchange, and returning blood to the arterial system, thereby bypassing both the heart and lungs. On the other hand, traditional venovenous ECMO support modalities typically drain blood from a central vein, perform gas exchange, and return blood to another central vein or the right atrium, thereby not relying on the lungs for gas exchange. A significant proportion of patients also suffer from severe pulmonary vascular dysfunction (e.g. pulmonary hypertension) leading to failure of the right ventricle/heart. These patients would traditionally be managed with VA ECMO, as there is a need for right heart support. While VA ECMO is effective in restoring appropriate hemodynamics and oxygenation/ventilation in this group, the duration of treatment on VA ECMO is significantly limited (order of weeks) relative to W ECMO (order of months to 1 year) due to the need for systemic anticoagulation, the risk of stasis in the left heart, and complications such as stroke or limb ischemia. Other issues with VA ECMO include limb ischemia and differential oxygenation, depending on the site of delivery.

[4] With a shift towards the use of ECMO and awake and ambulatory patients, recent advances in cannula technology have focused on single site and upper extremity cannulation. Such approaches facilitate the management of severe pulmonary dysfunction leading to right heart failure or isolated right heart failure in the absence of severe pulmonary dysfunction with W ECMO support modalities. To accomplish this, blood is drained from the systemic venous circulation or the right atrium and returned to the pulmonary artery, thereby bypassing the failing right ventricle. This modality, also known as venous-pulmonary artery (V-PA) ECMO, can be implemented through the use of multiple cannulas in the venous circulation: one draining from a central vein and a second returning to the pulmonary artery. Alternatively, this can be accomplished with a single, multistage cannula with two lumens, whereby the systemic venous blood is drained through the first lumen via the right atrium or a central vein, and oxygenated blood is returned through a second lumen directly into the pulmonary artery. [5] Although the concept of a dual lumen cannula for both drainage and return appears effective, several significant drawbacks in commercially available cannulas have limited the wide adoption of this technique. Existing cannulas have no method of stabilizing the drainage and return lumens in the intravascular/intracardiac space. This is extremely problematic as malposition of cannulas may have dire consequences. For example, positioning of blood return ports in the right ventricle, rather than the pulmonary artery, will exacerbate right heart failure and myocardial oxygen consumption by pumping pressurized blood into an already failing and distended chamber.

Moreover, given the thin wall of the right ventricle, perforation during placement or malpositioning of the cannula is possible, which may result in massive hemorrhage and death. Existing cannulas rely on innate stiffness and require (at least) daily monitoring for optimal position. Cardiac and patient motion as well as recoil stemming from the high velocity jet exiting the cannula tip, can result in displacement of the cannula despite appropriate initial delivery, requiring intensive monitoring of the cannula position as existing technology does not provide an adequate solution to fixate the device.

[6] Venous and arterial cannulas vary in design based on the intended placement location. Single stage venous cannulas are used to return blood to right heart and are placed in the vena cava at or near the level of the right atrium. Multistage venous cannulas are commonly used to drain blood, and are placed in various central veins including subclavian, internal jugular, and femoral, as well as directly in the right atrium itself when surgically implanted. Several newer generation cannulas are designed with multiple lumens that allow for a single cannula to both simultaneously drain and return blood. These cannulas are typically positioned with lumens for drainage in the superior and inferior vena cava and return directly to the right atrium. Alternatively, these cannulas can be placed with the return portion of the cannula in the pulmonary artery, which allows for both oxygenation/ventilation, thereby supporting the lungs, and bypass of the right heart, thereby supporting a failing right heart. Arterial cannulas are typically placed within major arteries such as the femoral artery, axillary artery, or aorta directly.

[7] Although these cannulas are effective in draining and returning blood, several drawbacks currently exist. One major challenge of existing cannulas is maintaining an appropriate and stable position to adequately provide cardiac or pulmonary support.

This is particularly problematic for newer generation cannulas that require positioning in specific chambers or vessels to function properly, such as those described above. For example, the Avalon Elite Bi-Caval Dual Lumen Catheter can drain blood from the central venous system, deliver it for gas exchange, and return blood to the right atrium, but must be positioned in a specific manner such that the return port is directed toward the tricuspid valve inlet. Similarly, the Protek Duo cannula must be positioned in a manner such that the drainage ports remain in the right atrium while the return ports stay in the pulmonary artery. In the absence of appropriate positioning, malfunction may result in harm to the patient, demonstrating the critical need for cannula stabilization and positioning. Similarly, cannulas are prone to migration and positioning must be carefully monitored, which often limits their full clinical utility. These cannulas, if improperly positioned, may perforate central vessels or the heart, and lead to fatal complications. Currently available cannulas do not have a mechanism to actively or passively fix their position in the intravascular space leaving the patient vulnerable to a myriad of complications. [8] Another major limitation of existing devices is cannula design which limits blood flow due to the small effective hydraulic diameter rendered by the placement of a tube within another (e.g. Protek duo (Abiomed) and Quantum (Spectrum Medical)).

This is hemodynamically unfavorable and limits flow rates, requiring the use of larger cannulas which are, in turn, associated with greater risk of iatrogenic injury. Moreover, cannulas with a hollow bore lumen within a second lumen may result in excess shear of blood cells, resulting in hemolysis, a common reason for discontinuation of extracorporeal support. Some catheters (e.g. the Avalon Elite Bi-Caval Dual Lumen Catheter) employ a membrane to separate arterial and venous drainage, but cannot support the right heart, nor have a mechanism for fixation. Other devices (e.g. the Protek Duo cannula and Spectrum Medical cannulas) employ hollow bore lumens within a second lumen, and neither have a method for fixation.

[9] Accordingly, there is a need in the art for a stabilized dual lumen cannula that can effectively provide both drainage and return for procedures such as those described above. Embodiments described herein fit this need.

SUMMARY OF THE INVENTION

[10] In one embodiment, a cannula includes a cannula body having a first proximal opening, a first distal opening and a first lumen extending therebetween, and a second proximal opening, a second distal opening, and a second lumen extending therebetween, wherein the second distal opening is configured distal of the first distal opening, and a retractable stabilization element configured on the cannula body between the first and second distal openings, the retractable stabilization element configured to define a plurality of voids therethrough when in an expanded state within a vessel. In one embodiment, the plurality of voids surround the cannula body. In one embodiment, the retractable stabilization element comprises a porous mesh. In one embodiment, the retractable stabilization element comprises a cage structure. In one embodiment, the retractable stabilization element comprises a circular perimeter profile. In one embodiment, the retractable stabilization element comprises a plurality of flexible arms. In one embodiment, the plurality of flexible arms comprise a shape memory alloy. In one embodiment, at least one of the plurality of flexible arms comprises an atraumatic tip. In one embodiment, the atraumatic tip comprises a rounded tip. In one embodiment, the atraumatic tip comprises a spherical tip. In one embodiment, the atraumatic tip comprises a smooth tip. In one embodiment, the retractable stabilization element comprises an inflatable balloon. In one embodiment, the inflatable balloon comprises a plurality of lobes. In one embodiment, the retractable stabilization element comprises a plurality of inflatable balloons. In one embodiment, the retractable stabilization element is connected to a retraction mechanism that is configured to move the stabilization element from an expanded state to a retracted state. In one embodiment, the cannula includes a locking mechanism connected to the retraction mechanism. In one embodiment, the first distal opening is one of a first plurality of distal openings configured adjacent to the first distal opening. In one embodiment, the first plurality of distal openings are only disposed on a common side of the cannula body. In one embodiment, the second distal opening is one of a second plurality of distal openings configured adjacent to the second distal opening. In one embodiment, at least two of the second plurality of distal openings are disposed on opposing sides of the cannula body.

[11] In one embodiment, a cannula includes a cannula body having a proximal opening, a distal opening and a lumen extending therebetween, and a retractable stabilization element configured on a distal portion of the cannula body and configured to define a plurality of voids therethrough when in an expanded state within a vessel. In one embodiment, the plurality of voids surround the cannula body. In one embodiment, the retractable stabilization element comprises a porous mesh. In one embodiment, the retractable stabilization element comprises a cage structure. In one embodiment, the retractable stabilization element comprises a circular perimeter profile. In one embodiment, the retractable stabilization element comprises a plurality of flexible arms. In one embodiment, the plurality of flexible arms comprise a shape memory alloy. In one embodiment, at least one of the plurality of flexible arms comprises an atraumatic tip. In one embodiment, the atraumatic tip comprises a rounded tip. In one embodiment, the atraumatic tip comprises a spherical tip. In one embodiment, the atraumatic tip comprises a smooth tip. In one embodiment, the retractable stabilization element comprises an inflatable balloon. In one embodiment, the inflatable balloon comprises a plurality of lobes. In one embodiment, the retractable stabilization element comprises a plurality of inflatable balloons. In one embodiment, the retractable stabilization element is connected to a retraction mechanism that is configured to move the stabilization element from an expanded state to a retracted state. In one embodiment, a locking mechanism is connected to the retraction mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[12] The foregoing purposes and features, as well as other purposes and features, will become apparent with reference to the description and accompanying figures below, which are included to provide an understanding of the invention and constitute a part of the specification, in which like numerals represent like elements, and in which:

[13] Figure 1 is a functional diagram of a dual lumen cannula having a retractable mesh cage according to one embodiment.

[14] Figure 2A is a diagram of a dual lumen cannula having retractable arms according to one embodiment, Fig. 2B is a diagram of a dual lumen cannula having an inflatable trilobed balloon according to one embodiment, Fig. 2C is a partial cross- sectional view of the dual lumen cannula of Fig. 2B, illustrating voids formed between the inflated trilobed balloon, the cannula body and a vessel wall, and Fig. 2D is a diagram of a dual lumen cannula having a retractable mesh according to one embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[15] It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a more clear comprehension of the present invention, while eliminating, for the purpose of clarity, many other elements found in stabilized intravascular cannulas. Those of ordinary skill in the art may recognize that other elements and/or steps are desirable and/or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein. The disclosure herein is directed to all such variations and modifications to such elements and methods known to those skilled in the art.

[16] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described.

[17] As used herein, each of the following terms has the meaning associated with it in this section.

[18] The articles “a” and “an” are used herein to refer to one or to more than one (/'.e. , to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

[19] “About” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20%, ±10%, ±5%, ±1 %, and ±0.1 % from the specified value, as such variations are appropriate.

[20] Ranges: throughout this disclosure, various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Where appropriate, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1 , 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range.

[21 ] Referring now in detail to the drawings, in which like reference numerals indicate like parts or elements throughout the several views, in various embodiments, presented herein is a stabilized intravascular cannula.

[22] Embodiments of the cannula described herein provide a right atrial to pulmonary artery cannula with fixation to prevent dislodgement and allow for optimal cannula placement and stabilization. Multiple fixation methods are described that allow for flexibility based on the size of the patient’s vasculature, and fixation can be controlled using a retraction/deployment mechanism. Retraction and deployment can be repeated for device repositioning, and deployment states can be locked as needed to stabilize target device positions. Moreover, embodiments of the cannula optimize venous drainage with side ports in the vena cava and right atrium. Drainage and return are separated by a low-profile flow divider to optimize hemodynamics, reduce shear stress, and allow for placement of smaller cannulas. Embodiments of the cannula represent a significant improvement in cannula technology for right ventricular and pulmonary support. Conventional devices fail to provide intravascular stabilization, let alone stabilization approaches that can be advanced, deployed, retracted and redeployed for repositioning as needed. Conventional cannulas require close monitoring for optimal positioning and potential for device migration remains significant, particularly as a greater proportion of patients are extubated while on ECMO, or ambulate freely. Taken together, advances represented by the embodiments described herein drastically reduce costs of care, complications, and improve patient survival.

[23] Embodiments of the cannula described herein utilize methods known in the art for percutaneous or open placement using fluoroscopy or echocardiography. Once positioned with the distal portion of the cannula in the pulmonary artery, the stabilization system is activated and deployed, and the cannula secured externally. Repositioning remains possible as the stabilization system can be retracted and redeployed.

[24] Embodiments described herein include two lumens at the proximal end of the cannula that attach to currently existing extracorporeal circuits. The outlet port drains blood from the right atrium and vena cava into an extracorporeal circuit, while the inlet port allows for return of oxygenated blood into the pulmonary artery. Uniquely, the atraumatic cannula mesh cage, balloon, or tines allows for fixation without vascular injury. Furthermore, the present invention uniquely allows vascular blood flow to continue around the exterior of the cannula when the stabilization elements are deployed or expanded. The cannula possesses a deployment/retraction mechanism with a locking capability to secure the device in place and allow for repositioning as needed. [25] Embodiments described herein provide novel approaches for fixation of intravascular catheters/cannulas. The embodiments are unique in several aspects. They provide a method for fixing a cannula within the intravascular space. This approach can be used to positionally stabilize cannulas within central veins, cardiac chambers, and arteries such as the aorta, axillary and pulmonary arteries. Multiple embodiments of the fixation method are described including a retractable spring mesh, retractable spring tines, and balloons. These retractable fixation methods are intended to facilitate cannula placement, removal, and repositioning as needed.

[26] Presently, no commercial devices provide stabilization methods. Existing cannulas rely on innate stiffness and require (at least) daily monitoring for optimal position. The devices and methods described herein advance cannula placement, particularly in the presence of tortuous vasculature. With stable and safe fixation of catheters, patients will ultimately require less intensive care and may potentially be able to have such devices in an ambulatory setting.

[27] Each of the cannula embodiments may utilize already existing methods for percutaneous or open placement which involve imaging modalities such as x-ray, ultrasonography, or cardiac echocardiography. Once in optimal position, the stabilization system which can be accommodated within the main body of the cannula at the time of insertion or be placed within side channels after, is deployed. The balloons, mesh or spring-loaded wires are manufactured to allow for simple retraction and redeployment, facilitating use and repositioning as needed.

[28] At the proximal end in one embodiment, a tubing connector allows for connection to existing extracorporeal circuits. The cannula inlet and outlet allow for drainage or return of blood. Uniquely, the cannula retractable mesh, retractable atraumatic spring tines, or balloon, in these renditions, allow for active fixation of the cannula intravascularly. These fixation components are controlled at the proximal end of the cannula and a locking mechanism allows for deployment or retraction of the fixation component.

[29] With reference now to Fig. 1 , a dual lumen cannula 100 with a retractable stabilization element 140 is disclosed according to one embodiment. It will be appreciated by those having ordinary skill in the art that the stabilization features described in this embodiment for a dual lumen cannula can apply to any single or multilumen cannula or catheter. The dual lumen cannula 100 includes a cannula body 101 having a first lumen 110 and a second lumen 120 separated by an interior wall 130 establishing lines for blood aspiration 102 and blood return 103. The first lumen 110 extends between a first lumen proximal opening 112 and at least one first lumen distal opening 116. The first lumen distal opening 116 can be one of multiple first lumen distal openings as depicted (e.g. 116, 116a). The first lumen proximal opening 112 can include a series of barbs or protrusions 114 for connecting medical tubing. The second lumen 120 extends between a second lumen proximal opening 122 and at least one second lumen distal opening 126. The second lumen distal opening 126 can be one of multiple second lumen distal openings as depicted (e.g. 126, 126a). The one or more second lumen distal opening 126 is disposed distal of the one or more first lumen distal opening 116. The first lumen 110 and interior wall 130 terminate at their distal ends proximal of the second lumen distal opening 126. The second lumen proximal opening

122 can include a series of barbs or protrusions 124 for connecting medical tubing. A retractable stabilization element 140 can for example include a spring or cage mesh with multiple voids 141 when in an expanded state. An expansion and retraction mechanism 105 is disposed at a proximal end of the cannula 100, that can also lock the stabilization element 140 in an expanded or retracted state. A section of the cannula 100 can include wire reinforcement to enhance integrity of the cannula and retain a curved geometry.

[30] The cage-like structure of the retractable stabilization element 140 allows for stabilization of the cannula 100 during patient movement, heart movement and turbulent fluid flows, all while allowing blood flow to continue past the expanded stabilization element around the exterior of the cannula via fluid communication through the voids 141. The retractable stabilization element 140 and retraction mechanism 105 can be configured using configurations known in the art for mechanical manipulation. For example, a push-pull wire system can be implemented that runs a wire through the cannula and connects to the expandable cage. By pushing or pulling the wire, the cage can be expanded or retracted accordingly. This mechanism can be controlled by a handle or a knob at the retraction mechanism 105. A shape memory material such as Nitinol can be utilized. In one embodiment, nickel-titanium shape memory alloy has the ability to expand to a predefined shape. By incorporating Nitinol into the cage design, it can be expanded or retracted to predictable geometries, for example by deploying the cage from a sheath for expansion, and moving it back into a sheath for retraction.

Similarly, shape memory polymers can be utilized. In one embodiment, the expandable cage can be deployed and manipulated using a balloon, which when inflated expands the cage and by deflating retracts the cage. As shown in later embodiments, balloon geometries can be implemented so that they do not impede blood flow when inflated. In one embodiment, a threaded component is integrated into the cage design, and by rotating the screw-like structure at the proximal end of the catheter, the cage expands or contracts accordingly. A locking mechanism can be implemented to hold a particular expansion or retraction state as needed. Depending on the retraction/expansion modality, the locking mechanism can arrest movement of the retraction/expansion mechanism to lock position, using for example a friction or interference fit can be utilized, or a mechanical stop such as aligned openings or protrusions with an insert or adjacent structure for arresting movement of the retraction/expansion mechanism. A latch, catch or level that engages with the retraction/expansion mechanism can be utilized. A ratchet mechanism or external fastener such as threaded screws, clips, or bands are also possible.

[31] The stabilization element can include one or more structures that allow blood flow therethrough while in an expanded position. For example, mesh structures can be implemented that consist of a network of interconnected wires or fibers that form a flexible lattice when expanded. These structures can be deployed around the cannula shaft to enhance stability without significantly impeding blood flow. The mesh structure allows for flexibility and conformability while maintaining radial support. Open-cell structures with a porous configuration can also be utilized, made from materials like Nitinol or polymer foams. In one embodiment, a helical spring or coil-shaped structure is expanded and contracted using a mechanism described above or a twisting mechanism, which allows for flexibility and adaptability to the vessel anatomy while maintaining radial support. They can be made from materials such as stainless steel or shape memory alloys. Expandable rings or bands can also be utilized, having a circular geometry that can be expanded or contracted. They can utilize shape memory materials or flexible materials like silicone or polymer. Inflatable balloons that do not assume an occlusive shape upon expansion or do not otherwise compromise blood flow can also be utilized. Collapsible elements such as retractable hooks, arms, or tines that can be deployed then retracted to provide stability during a procedure can also be used.

[32] With reference now to Fig. 2A, a dual lumen cannula 200 with retractable stabilization arms 240 such as retractable tine elements having atraumatic tips 241 are disclosed according to one embodiment. It will be appreciated by those having ordinary skill in the art that the stabilization features described in this embodiment for a dual lumen cannula can apply to any single or multi-lumen cannula or catheter. The dual lumen cannula 200 includes a cannula body 201 having a first lumen 210 and a second lumen 220 separated by an interior wall 230 establishing lines for blood aspiration 202 and blood return 203. The first lumen 210 extends between a first lumen proximal opening 212 and at least one first lumen distal opening 216. The first lumen distal opening 216 can be one of multiple first lumen distal openings as depicted (e.g. 216, 216a). The first lumen proximal opening 212 can include a series of barbs or protrusions 214 for connecting medical tubing. The second lumen 220 extends between a second lumen proximal opening 222 and at least one second lumen distal opening 226. The second lumen distal opening 226 can be one of multiple second lumen distal openings as depicted (e.g. 226, 226a). The one or more second lumen distal opening 226 is disposed distal of the one or more first lumen distal opening 216.

The first lumen 210 and interior wall 230 terminate at their distal ends proximal of the second lumen distal opening 226. The second lumen proximal opening 222 can include a series of barbs or protrusions 224 for connecting medical tubing. A retractable stabilization element 240 can for example include springing tines that have an atraumatic tip 241 such as a small spherical element at the tip. An expansion and retraction mechanism 205 is disposed at a proximal end of the cannula 200, that can also lock 206 the stabilization element 240 in an expanded or retracted state. Adjacent arms of the stabilization element 240 form voids 241 therebetween, allowing fluid communication therethrough while the stabilization element is in an expanded state.

[33] The atraumatic stabilization tip 241 can be designed to enhance anchoring and stability within the vessel, preventing migration while minimizing trauma to surrounding tissues. Small hooks, projections, or anchors that engage with the vessel walls can be incorporated into one or more of the stabilization elements 240. The shape and size of these elements are selected to ensure effective anchoring without causing excessive tissue damage or irritation. Smooth and rounded edges can also be incorporated to reduce risk of tissue trauma. Stabilization tips can be designed long enough to provide sufficient anchoring force but not excessively long, to minimize tissue interaction. The placement of stabilization tips can be determined to ensure even distribution along the cannula, promoting stable fixation without concentrating excessive stress on specific regions. The stabilization tips and components such as arms of springing tines are typically made of a flexible material such as stainless steel or nitinol. These components can easily slide into a sheath and provide a low profile during advancement to the target site, then deploy away from the longitudinal axis of the device as the sheath is pulled back. Tapered or blunt tips instead of sharp points can 1 be utilized where possible. Specialized surface coatings such as hydrophilic coating can facilitate atraumatic properties of the stabilization tips and can be applied by reducing friction during deployment, minimizing the potential for tissue damage. Biocompatible coating and materials can also be applied to minimize the risk of adverse reactions or inflammatory responses, allowing for better tissue compatibility and healing.

[34] In an alternate embodiment, as shown in Figs. 2B and 2C, a dual lumen cannula 200’ can utilize a retractable stabilization balloon 260 near the distal end 266, such as an inflatable trilobed balloon forming voids 261 therebetween as depicted according to one embodiment. It will be appreciated by those having ordinary skill in the art that the stabilization features described in this embodiment for a dual lumen cannula can apply to any single or multi-lumen cannula or catheter. The inflatable trilobed balloon can include another number of balloon lobes in a cluster, such as for example 4, 5, 6 or more balloon lobes. The stabilization balloon 260 can include multiple inflatable lobe sections that form voids 261 therebetween, which allows blood flow to pass though when the element is fully expanded for stabilization within the vessel. As shown in the partial cross-sectional view of Fig. 2C, when the stabilization balloon 260 is inflated within a vessel 270, voids 261 are formed where gaps remain between the cannula 200 and stabilization balloon 260, and between the stabilization balloon 260 and the vessel wall 270. The stabilization balloon in one embodiment can include one inflatable chamber that inflates a single balloon having a geometry (e.g. lobes or some other geometry) with voids built into the expanded state. The stabilization balloon in one embodiment can include multiple inflatable balloons each with separated inflatable chambers that touch or that are spaced apart, forming voids therebetween. Balloon materials can be selected to achieve a desired shape upon inflation. The balloon surface can for example incorporate different sections that have different mechanical properties, such as elasticity, compliance, and strength, to allow controlled but variable expansion and deformation. Different materials such as polyethylene, polyurethane, and silicone can be used, with varying thicknesses or reinforcing materials as needed to achieve the desired shape upon inflation. Structural features such as reinforcing rings or bands can be integrated into the balloon structure. These rings, typically made of a less flexible material, are positioned at strategic locations along the balloon's length. They help restrict radial expansion in specific regions, thereby promoting controlled deformation and directing the shape transformation. The balloon can be designed with varying wall thickness along their length. Thinner regions can allow for greater expansion, resulting in a more pronounced deformation and irregular shape in those areas. Shape memory polymers can be utilized in the balloon construction, assuming a specific shape upon inflation. One or more of these techniques along with others known in the art can be utilized to inflate one or more balloon structures into an irregular or non-circular shape so that blood can maintain continuous flow through the stabilization balloon while fully expanded within the target vessel. Balloon inflation and deflation can be achieved using methods well known in the art for controlling medical device balloons.

[35] With reference now to Fig. 2D, a cannula 300 having a retractable mesh is shown according to one embodiment. It will be appreciated by those having ordinary skill in the art that the stabilization features described in this embodiment for a single lumen cannula can apply to any single or multi-lumen cannula or catheter. The cannula

300 includes a cannula body 301 having a lumen 310 extending between a first opening 312 and at least one distal opening 316. The distal opening 316 can be one of multiple distal openings as depicted (e.g. 316, 316a). The proximal opening 312 can include a series of barbs or protrusions 314 for connecting medical tubing. A retractable stabilization element 304 can for example include a mesh with multiple voids 341 when in an expanded state. An expansion and retraction mechanism 305 is disposed at a proximal end of the cannula 300, that can also lock the stabilization element 304 in an expanded or retracted state using a locking mechanism 306. A section of the cannula 300 can include wire reinforcement 307 to enhance integrity of the cannula and retain a curved geometry. The mesh structure of the retractable stabilization element 340 allows for stabilization of the cannula 300 during patient movement, heart movement and turbulent fluid flows, all while allowing blood flow to continue past the expanded stabilization element around the exterior of the cannula via fluid communication through the voids 341 .

[36] The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. While this invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of this invention may be devised by others skilled in the art without departing from the true spirit and scope of the invention.

Claims

CLAIMS What is claimed is:

1. A cannula comprising: a cannula body having: a first proximal opening, a first distal opening and a first lumen extending therebetween, and a second proximal opening, a second distal opening, and a second lumen extending therebetween, wherein the second distal opening is configured distal of the first distal opening; and a retractable stabilization element configured on the cannula body between the first and second distal openings, the retractable stabilization element configured to define a plurality of voids therethrough when in an expanded state within a vessel.

2. The cannula of claim 1 , wherein the plurality of voids surround the cannula body.

3. The cannula of claim 1 , wherein the retractable stabilization element comprises a porous mesh.

4. The cannula of claim 1 , wherein the retractable stabilization element comprises a cage structure.

5. The cannula of claim 1 , wherein the retractable stabilization element comprises a circular perimeter profile.

6. The cannula of claim 1 , wherein the retractable stabilization element comprises a plurality of flexible arms.

7. The cannula of claim 6, wherein the plurality of flexible arms comprise a shape memory alloy.

8. The cannula of claim 6, wherein at least one of the plurality of flexible arms comprises an atraumatic tip.

9. The cannula of claim 8, wherein the atraumatic tip comprises a rounded tip.

10. The cannula of claim 8, wherein the atraumatic tip comprises a spherical tip.

11 . The cannula of claim 8, wherein the atraumatic tip comprises a smooth tip.

12. The cannula of claim 1 , wherein the retractable stabilization element comprises an inflatable balloon.

13. The cannula of claim 12, wherein the inflatable balloon comprises a plurality of lobes.

14. The cannula of claim 1 , wherein the retractable stabilization element comprises a plurality of inflatable balloons.

15. The cannula of claim 1 , wherein the retractable stabilization element is connected to a retraction mechanism that is configured to move the stabilization element from an expanded state to a retracted state.

16. The cannula of claim 15 further comprising: a locking mechanism connected to the retraction mechanism.

17. The cannula of claim 1 , wherein the first distal opening is one of a first plurality of distal openings configured adjacent to the first distal opening.

18. The cannula of claim 17, wherein the first plurality of distal openings are only disposed on a common side of the cannula body.

19. The cannula of claim 1 , wherein the second distal opening is one of a second plurality of distal openings configured adjacent to the second distal opening.

20. The cannula of claim 19, wherein at least two of the second plurality of distal openings are disposed on opposing sides of the cannula body.

21. A cannula comprising: a cannula body having a proximal opening, a distal opening and a lumen extending therebetween; and a retractable stabilization element configured on a distal portion of the cannula body and configured to define a plurality of voids therethrough when in an expanded state within a vessel.

22. The cannula of claim 21 , wherein the plurality of voids surround the cannula body.

23. The cannula of claim 21 , wherein the retractable stabilization element comprises a porous mesh.

24. The cannula of claim 21 , wherein the retractable stabilization element comprises a cage structure.

25. The cannula of claim 21 , wherein the retractable stabilization element comprises a circular perimeter profile.

26. The cannula of claim 21 , wherein the retractable stabilization element comprises a plurality of flexible arms.

27. The cannula of claim 26, wherein the plurality of flexible arms comprise a shape memory alloy.

28. The cannula of claim 21 , wherein at least one of the plurality of flexible arms comprises an atraumatic tip.

29. The cannula of claim 28, wherein the atraumatic tip comprises a rounded tip.

30. The cannula of claim 28, wherein the atraumatic tip comprises a spherical tip.

31 . The cannula of claim 28, wherein the atraumatic tip comprises a smooth tip.

32. The cannula of claim 21 , wherein the retractable stabilization element comprises an inflatable balloon.

33. The cannula of claim 32, wherein the inflatable balloon comprises a plurality of lobes.

34. The cannula of claim 21 , wherein the retractable stabilization element comprises a plurality of inflatable balloons.

35. The cannula of claim 21 , wherein the retractable stabilization element is connected to a retraction mechanism that is configured to move the stabilization element from an expanded state to a retracted state.

36. The cannula of claim 35 further comprising: a locking mechanism connected to the retraction mechanism.