FIELD OF THE INVENTION

This application generally relates to devices for use in the human body, such as percutaneously implanted devices and methods for adjusting the flow of fluid, such as blood, within the human body.

BACKGROUND

For a number of medical conditions, there is benefit in adjusting the flow of fluid within the human body, for example, through a passage between two body cavities. Such a passage is typically used in catheterization procedures where the catheter is delivered through a patient's vasculature. In some catheterization procedures, there is a benefit in moving from one cavity to another cavity by creating a passage. For example, such a passage may be formed between the right side of the heart and the left side of the heart, e.g., between the right atrium toward the left atrium, where clinical procedures are done on the left side of the heart using an entry from the right side of the heart. Such clinical procedures include, e.g., arrhythmia ablation procedures in the left atrium and mitral valve repair activities.

In addition, a passage may be created and maintained in a heart wall between two heart chambers for housing a shunt for redistributing blood from one heart chamber to another to address pathologies such as heart failure (HF), myocardial infarction (MI), and pulmonary arterial hypertension (PAH). HF is the physiological state in which cardiac output is insufficient to meet the needs of the body or to do so only at a higher filling pressure. There are many underlying causes of HF, including MI, coronary artery disease, valvular disease, hypertension (such as PAH), and myocarditis. Chronic heart failure is associated with neurohormonal activation and alterations in autonomic control. Although these compensatory neurohormonal mechanisms provide valuable support for the heart under normal physiological circumstances, they also play a fundamental role in the development and subsequent progression of HF.

HF is generally classified as either systolic heart failure (“SHF”) or diastolic heart failure (“DHF”). In SHF, the pumping action of the heart is reduced or weakened. A common clinical measurement is the ejection fraction, which is a function of the blood ejected out of the left ventricle (stroke volume) divided by the maximum volume in the left ventricle at the end of diastole or relaxation phase. A normal ejection fraction is greater than 50%. Systolic heart failure generally causes a decreased ejection fraction of less than 40%. Such patients have heart failure with reduced ejection fraction (“HFrEF”). A patient with HFrEF may usually have a larger left ventricle because of a phenomenon called “cardiac remodeling” that occurs secondarily to the higher ventricular pressures.

In DHF, the heart generally contracts well, with a normal ejection fraction, but is stiffer, or less compliant, than a healthy heart would be when relaxing and filling with blood. Such patients are said to have heart failure with preserved ejection fraction (“HFpEF”). This stiffness may impede blood from filling the heart and produce backup into the lungs, which may result in pulmonary venous hypertension and lung edema. HFpEF is more common in patients older than 75 years, especially in women with high blood pressure.

Both variants of HF have been treated using pharmacological approaches, which typically involve the use of vasodilators for reducing the workload of the heart by reducing systemic vascular resistance, as well as diuretics, which inhibit fluid accumulation and edema formation, and reduce cardiac filling pressure. No pharmacological therapies have been shown to improve morbidity or mortality in HFpEF whereas several classes of drugs have made an important impact on the management of patients with HFrEF, including renin-angiotensin antagonists, neprilysin inhibitors, beta blockers, mineralocorticoid antagonists and sodium-glucose co-transporter-2 (SGLT2) inhibitors, Nonetheless, in general, HF remains a progressive disease and most patients have deteriorating cardiac function and symptoms over time. In the U.S., there are over 1 million hospitalizations annually for acutely worsening HF and mortality is higher than for most forms of cancer.

In more severe cases of HFrEF, mechanical circulatory support (MCS) devices such as mechanical pumps are used to reduce the load on the heart by performing all or part of the pumping function normally done by the heart. Chronic left ventricular assist devices (“LVAD”), the total artificial heart, and cardiac transplantation are used as measures of last resort. However, such assist devices typically are intended to improve the pumping capacity of the heart, to increase cardiac output to levels compatible with normal life, and to sustain the patient until a donor heart for transplantation becomes available. This usage of MCS is also known as “bridge to transplant” therapy”. As the supply of donor hearts for transplantation is insufficient for the demand, more often MCS is the only therapeutic option—also known as “destination therapy.” Such mechanical devices enable propulsion of significant volumes of blood (liters/min) but are limited by a need for a power supply, relatively large pumps, and pose a risk of hemolysis, thrombus formation, and infection. Temporary assist devices, intra-aortic balloons, and pacing devices have also been used.

Various devices have been developed using stents to modify blood pressure and flow within a given vessel, or between chambers of the heart. For example, U.S. Pat. No. 6,120,534 to Ruiz is directed to an endoluminal stent for regulating the flow of fluids through a body vessel or organ, for example, for regulating blood flow through the pulmonary artery to treat congenital heart defects. The stent may include an expandable mesh having balloon-expandable lobed or conical portions joined by a shape-memory constricted region, which limits flow through the stent. The constricted region may be adjusted in vivo, and in addition may be heated to recover a maximum degree of constriction. Ruiz is silent on the treatment of HF or the reduction of left atrial pressure.

U.S. Patent Publication No. 2013/0178784 to McNamara describes an adjustable pressure relief shunt that may be expanded, e.g., via an inflation balloon. A tubular body of the shunt may be plastically deformed in vivo, such that the size of the shunt may be repeatedly adjusted by a variety of mechanisms, for example, elastically wound springs or a series of pawls and one-way mechanical ramps, responsive to measurements of the patient's physiological parameters. A key drawback to the approach described in that patent is the hysteresis effect, i.e., non-reversible changes in the underlying crystalline structure that occur when the shunt is permanently deformed. Importantly, such plastic deformation may lead to stress and fatigue-related fracture of the device.

U.S. Pat. No. 6,468,303 to Amplatz et al. describes a collapsible medical device and associated method for shunting selected organs and vessels. Amplatz describes that the device may be suitable to shunt a septal defect of a patient's heart, for example, by creating a shunt in the atrial septum of a neonate with hypoplastic left heart syndrome (“HLHS”). That patent also describes that increasing mixing of pulmonary and systemic venous blood improves oxygen saturation, and that the shunt may later be closed with an occluding device. Amplatz is silent on the treatment of HF or the reduction of left atrial pressure, as well as on means for regulating the rate of blood flow through the device.

Implantable interatrial shunt devices have been successfully used in patients with severe symptomatic heart failure. By diverting or shunting blood from the left atrium (“LA”) to the right atrium (“RA”), the pressure in the left atrium is lowered or prevented from elevating as high as it would otherwise (left atrial decompression). Such an accomplishment would be expected to prevent, relieve, or limit the symptoms, signs, and syndromes associated of pulmonary congestion. These include severe shortness of breath, pulmonary edema, hypoxia, the need for acute hospitalization, mechanical ventilation, and death.

Shunt flow is generally governed by the pressure gradient between the atria and the fluid mechanical properties of the shunt device. The latter are typically affected by the shunt's geometry and material composition. For example, the general flow properties of similar shunt designs have been shown to be related to the mean interatrial pressure gradient and the effective orifice diameter.

Percutaneous implantation of interatrial shunts generally requires transseptal catheterization immediately preceding shunt device insertion. The transseptal catheterization system is generally placed from an entrance site in the femoral vein, across the interatrial septum in the region of fossa ovalis (“FO”), which is the central and thinnest region of the interatrial septum. The FO in adults is typically 15-20 mm in its major axis dimension and <3 mm in thickness, but in certain circumstances may be up to 10 mm thick. LA chamber access may be achieved using a host of different techniques familiar to those skilled in the art, including but not limited to: needle puncture, stylet puncture, screw needle puncture, and radiofrequency ablation. The passageway between the two atria is dilated to facilitate passage of a shunt device having a desired orifice size. Dilation generally is accomplished by advancing a tapered sheath/dilator catheter system or inflation of an angioplasty type balloon across the FO. This is the same general location where a congenital secundum atrial septal defect (“ASD”) would be located.

U.S. Patent Publication No. 2005/0165344 to Dobak, III describes apparatus for treating heart failure that includes a tubular conduit having an emboli filter or valve, the device configured to be positioned in an opening in the atrial septum of the heart to allow flow from the left atrium into the right atrium. Dobak discloses that shunting of blood may reduce left atrial pressures, thereby preventing pulmonary edema and progressive left ventricular dysfunction, and reducing LVEDP. Dobak describes that the device may include deployable retention struts, such as metallic arms that exert a slight force on the atrial septum on both sides and pinch or clamp the device to the septum.

In addition, following implantation of a shunt device within a heart wall, tissue ingrowth including an endothelial layer or neointima layer typically forms on the device, thereby inhibiting thrombogenicity of the shunt device, and narrowing the size of the passage through the device.

SUMMARY OF THE INVENTION

The present invention overcomes the drawbacks of previously-known systems and methods by providing devices with dimensions that not only may be increased, but also may be reduced in vivo, and methods of making and using the same.

In particular, the present invention overcomes the limitations of previously known devices and methods by providing an implantable device with a composite structure exhibiting both superelastic and shape-memory properties at body temperature. Dimensions that may affect blood flow or other intended interactions between the implanted device and its biological host can be repeatedly altered in either direction by mechanical deformation of one crystalline phase of the shape-memory component in one direction and reversing the direction by temperature induction of a crystalline phase change of the shape-memory component material to its original dimension, greatly simplifying catheter related manipulations.

Under one aspect, an interatrial shunt for placement at an atrial septum of a patient's heart is provided herein. The interatrial shunt includes a body that includes first and second regions coupled in fluid communication by a neck region. The body includes a shape-memory material. The body defines a passageway through the neck region for blood to flow between a first atrium and a second atrium. The first and second regions are superelastic at body temperature, and the neck region is malleable at body temperature. A flow area of the passageway through the neck region may be adjusted in vivo.

The first and second regions that are superelastic may include NITINOL having an austenitic finish temperature (Af) between 5-20° C. The neck region that is malleable may include NITINOL having an austenitic finish temperature (Af) between 45-60° C. The neck region may be mechanically expandable. The neck region may be thermally contractible.

Under another aspect, an interatrial shunt is provided for placement at an atrial septum of a patient's heart for adjustably regulating fluid flow therethrough. The interatrial shunt may include a first expandable end region configured to be placed in a first atrium of the heart, and a second expandable end region configured to be placed in a second atrium of the heart. The first and second expandable end regions may include self-expanding superelastic material. The interatrial shunt may include a neck region between the first and second expandable end regions. The neck region may be configured for placement at the atrial septum. The neck region may include malleable shape-memory material. The interatrial shunt may define a passageway through the neck region for blood to flow between the first atrium and the second atrium. The neck region may be heat treated to exhibit different shape memory properties than the first and second expandable end regions such that a cross-sectional area of the passageway is adjustable in vivo.

The malleable shape-memory material may be configured to be expanded in vivo such that the passageway expands from the cross-sectional area to a second cross-sectional area larger than the cross-sectional area. The malleable shape-memory material may be configured to be contracted in vivo such that the passageway contracts from the second cross-sectional area to a third cross-sectional area smaller than the second cross-sectional area. The cross-sectional area may be between 4.9 to 28.3 mm2and the second cross-sectional area and the third cross-sectional area may be between 15.9 to 78.6 mm2. The malleable shape-memory material may include NITINOL having an austenitic finish temperature (Af) between 45-60° C. The self-expanding superelastic material may include NITINOL having an austenitic finish temperature (Af) between 5-20° C. The malleable shape-memory material may be mechanically expandable. The malleable shape-memory material may be thermally contractible. The cross-sectional area of the neck region may be smaller than respective cross-sectional areas of at least one of the first and second expandable end regions. The first and second expandable end regions may extend into the first and second atria, respectively, such that respective ends of the first and second expandable end regions may not contact the atrial septum. The first and second expandable end regions and the neck region may comprise a diabolo-shaped shunt. The neck region may include a cylindrical shunt. The cylindrical shunt may be outside of the diabolo-shaped shunt. The cylindrical shunt may be formed of the malleable shape-memory material such that the cylindrical shunt radially constrains a dimension of the diabolo-shaped shunt at the neck region, and the diabolo-shaped shunt may self-expand at the neck region responsive to the malleable shape memory material expanding to a second cross-sectional area. The cylindrical shunt may be inside of the diabolo-shaped shunt. The cylindrical shunt may not be directly coupled to the diabolo-shaped shunt and the neck region. The device may further include an encapsulant indirectly and elastically coupling the cylindrical shunt to the diabolo-shaped shunt. Contraction of the cylindrical shunt may not cause contraction of the diabolo-shaped shunt at the neck region. The diabolo-shaped shunt and the cylindrical shunt may be integrally formed from a common frame. The first and second expandable end regions and the neck region may be integrally formed from a common frame. The first and second expandable end regions and the neck region may be at least partially encapsulated with a biocompatible material.

Under another aspect, an interatrial shunt for adjustably regulating fluid flow in a heart having a first atrium, a second atrium, and an atrial septum is provided. The interatrial shunt may include a first region that includes a self-expanding superelastic material configured to be placed in the first atrium. The first region may be superelastic at body temperature. The interatrial shunt may include a second region that includes a malleable shape-memory material configured to be placed through an opening in the atrial septum so as to provide fluid flow from the first atrium to the second atrium. The second region may be malleable at body temperature. The malleable shape-memory material may have a first cross-sectional area. The malleable shape-memory material may be expandable from the first cross-sectional area to a second cross-sectional area. The malleable shape-memory material may be contractible from the second cross-sectional area to a third cross-sectional area.

The self-expanding superelastic material may include NITINOL having an austenitic finish temperature (Af) between 5-20° C., and the malleable shape-memory material may include NITINOL having an austenitic finish temperature (Af) between 45-60° C. The malleable shape-memory material may be mechanically expandable and thermally contractible. The interatrial shunt may include a third region that includes a second self-expanding superelastic material, is configured to be placed in the second atrium, and is coupled to the second region.

In accordance with another aspect, a device is provided for adjustably regulating fluid flow therethrough. The device may include a first component including a first self-expanding superelastic material, and a second component coupled to the first component and including a first malleable shape-memory material. The first malleable shape-memory material may have a first cross sectional area. The first malleable shape-memory material may be expandable to a second cross sectional area. The first malleable shape-memory material may be contractible to a third cross sectional area.

In some examples, the first self-expanding superelastic material includes NITINOL having an austenitic finish temperature (Af) of less than body temperature (normally ˜37° C.). Illustratively, the Af of the NITINOL of the first self-expanding superelastic material may be between 5-20° C.

In some examples, the first malleable shape-memory material includes NITINOL having an austenitic finish temperature (Af) of greater than body temperature or 37° C. Illustratively, the Af of the NITINOL of the malleable shape-memory material may be between 45-60° C. This is higher than body temperature when febrile but not high enough to cause permanent injury such a protein denaturation from brief exposure.

In some examples, the first malleable shape-memory material is mechanically expandable. In some examples, the first malleable shape-memory material is thermally contractible. In some examples, the first malleable shape-memory material is joined to the first self-expanding superelastic material by welding. In some examples, the device includes an encapsulant covering at least a portion of at least one of the first component and the second component. Optionally, the encapsulant joins the first malleable shape-memory material to the first self-expanding superelastic material.

In some examples, the first cross sectional area is smaller than the third cross sectional area. In some examples, the first cross sectional area is larger than the third cross sectional area.

In some examples, the device further includes a third component including a second self-expanding superelastic material and coupled to the first component and the second component. Optionally, the first component includes an inlet, the second component includes a neck, and the third component includes an outlet fluidically coupled to the inlet via the neck. As a further option, the cross sectional area of the neck is smaller than respective cross sectional areas of at least one of the inlet and the outlet. As a still further option, the inlet and outlet anchor the device within an opening through a septum between two chambers within the body, and the neck provides a channel for flow between these chambers. In other options, the cross sectional area of the neck is larger than respective cross sectional areas of at least one of the inlet (ingress of blood flow) and the outlet (egress of blood flow). Optionally, the second component is configured to engage an opening in the human body. As a further option, the opening may be created through a fossa ovalis of an interatrial septum between a right atrium and a left atrium. The neck may be configured to engage the opening, the inlet may be configured to extend into the right atrium, and the outlet may be configured to extend into the left atrium.

In some examples, the first component is configured to engage a lumen in the human body. Optionally, the lumen includes a blood vessel, and the first and third components are configured to engage the blood vessel. The neck may be configured to be disposed adjacent to an ostium of the blood vessel.

In some examples, the device includes a third component including a second malleable shape-memory material and coupled to the first component and the second component. Optionally, the second malleable shape-memory material has a fourth cross sectional area permitting a fourth rate of fluid flow therethrough. The second malleable shape-memory material may be expandable to a fifth cross sectional area permitting a fifth rate of fluid flow therethrough. The second malleable shape-memory material may be contractible to a sixth cross sectional area permitting a sixth rate of fluid flow therethrough. Optionally, the second component includes an inlet and the third component includes an outlet fluidically coupled to the inlet via the first component. As a further option, the inlet is configured to engage a blood vessel in the human body, the first component is configured to engage the blood vessel, and the outlet is configured to extend into an ostium of the blood vessel.

In some examples, the device further includes a valve disposed in the second component. The first component may be configured to engage a blood vessel in the human body, and the second component may extend into the blood vessel.

In some examples, the second component is located inside of the first component.

In some examples, the first component includes a diabolo-shaped shunt having a neck, and the second component includes a cylindrical shunt. Optionally, the cylindrical shunt is outside of the diabolo-shaped shunt. As a further option, the first malleable shape-memory material may radially constrain a dimension of the neck. The first malleable shape-memory material optionally radially contacts an outer surface of the neck so as to constrain the neck from self-expanding to a larger dimension. Optionally, the neck self-expands responsive to the first malleable shape memory material expanding to the second cross sectional area. The device optionally further includes an encapsulant forming an inner lumen through the first component and an outer covering of the first component and the second component.

In other examples, the cylindrical shunt is inside of the diabolo-shaped shunt. Optionally, the cylindrical shunt is inside of, and not directly coupled to, the neck of the diabolo-shaped shunt. The device optionally further includes an encapsulant indirectly and elastically coupling the cylindrical shunt to the diabolo-shaped shunt such that the encapsulant forms a lumen through the inner cylindrical shunt. Optionally, contraction of the cylindrical shunt does not cause contraction of neck of the outer diabolo-shaped shunt. Optionally, the neck of the diabolo-shaped shunt is self-expandable to a fourth cross sectional area.

In some examples, the second component is located inside of the first component.

Optionally, the first malleable shape-memory material radially constrains a dimension of the first component. Optionally, the first malleable shape-memory material radially contacts an inner surface of the first component so as to constrain the first component from contracting to a smaller dimension. Optionally, the first component self-contracts responsive to the first malleable shape memory material contracting to the third cross sectional area. Optionally, the device further includes an encapsulant forming an outer covering of the first component and the second component.

Under another aspect, a method for reducing and increasing an internal dimension of a device in vivo is provided. The method may include inserting into a fluid path first and second components coupled to one another. The first component may include a self-expanding superelastic material, and the second component may include a malleable shape-memory material having a first cross sectional area. The method may include expanding the malleable shape-memory material to a second cross sectional area; and contracting the malleable shape-memory material to a third cross sectional area.

In some examples, contracting the malleable shape-memory material includes heating the malleable shape-memory material. In some examples, the heating includes flowing heated saline through the device via a catheter. In some examples, the heating includes applying radio frequency (RF) energy to the device. In some examples, expanding the malleable shape-memory material includes expanding a balloon within the malleable shape-memory material.

Under another aspect, a method for adjustably regulating fluid flow is provided. The method may include inserting into a fluid path first and second components coupled to one another. The first component may include a self-expanding superelastic material, and the second component may include a malleable shape-memory material having a first cross sectional area permitting a first rate of fluid flow therethrough. The method may include expanding the malleable shape-memory material to a second cross sectional area permitting a second rate of fluid flow therethrough; and contracting the malleable shape-memory material to a third cross sectional area permitting a third rate of fluid flow therethrough.

In some examples, contracting the malleable shape-memory material includes heating the malleable shape-memory material. In some examples, the heating includes flowing heated saline through the device via a catheter. In some examples, the heating includes applying radio frequency (RF) energy to the device. In some examples, expanding the malleable shape-memory material includes expanding a balloon within the malleable shape-memory material.

Under another aspect, a repositionable device for fixation within a body lumen is provided. The device may include a first component including a self-expanding superelastic material; and a second component coupled to the first component and including a malleable shape-memory material. The self-expanding superelastic material may have a predetermined fully expanded dimension. The second component may have a first dimension suitable for deployment through a catheter. The malleable shape-memory material may be expandable to a second dimension for fixation within a body lumen. The malleable shape-memory material may be thermally transitionable to a third dimension. The malleable shape-memory material may be mechanically re-expandable to a fourth dimension.

Under another aspect, a method for adjustably fixating a device within a body lumen is provided. The method may include inserting into a body lumen a device including first and second components coupled to one another. The first component may include a self-expanding superelastic material. The second component may include a malleable shape-memory material having a first dimension. The method may include expanding the malleable shape-memory material to a second dimension to fixate the device within a body lumen. The method may include thermally contracting the malleable shape-memory material. The method may include repositioning the device within the body lumen while the malleable shape-memory material is thermally contracted. The method may include mechanically re-expanding the malleable shape-memory material to a third dimension to fixate the device within the body lumen.

In some examples, thermally contracting the malleable shape-memory material includes heating the malleable shape-memory material. In some examples, the heating includes flowing heated saline through the device via a catheter. In some examples, the heating includes applying radio frequency (RF) energy to the device. In some examples, the mechanically expanding the malleable shape-memory material includes expanding a balloon within the malleable shape-memory material.

In any of the aforementioned devices and methods, the first component and the second component optionally are integrally formed from a common frame with one another.

Under another aspect, a dilator for enlarging an opening through a region of the human body is provided. The dilator may include a sheath having a proximal end and a distal end; and a dilator disposed at the distal end of the sheath and including a tip, an enlarged region, and a reduced region. The reduced region may be sized so as to securably engage with the distal end of the sheath. The enlarged region may be sized so as to provide a smooth profile between the sheath and the tip. A distal end of the tip may taper to approximately a point. At least the enlarged region and the reduced region may include a martensitic shape-memory material having an austenitic finish temperature (Af) substantially greater than 37° C. such that, upon application of heat within the body, the shape memory material returns to a smaller, heat-set outer dimension such that the dilator has a substantially smooth, reduced size profile.

In some examples, the tip also includes the martensitic shape-memory material. In some examples, the tip includes a self-expanding superelastic material. The tip, the reduced region, and the enlarged region optionally are integrally formed from a common frame with one another.

Under another aspect, a system is provided that includes such a dilator, and a device to deploy in the opening.

Under another aspect, a method for forming an enlarged opening through a region of the human body is provided. The method may include disposing a guidewire through the region of the human body to form an opening. The method may include pushing a dilator over the guidewire and through the opening to form an enlarged opening. The method may include heating the dilator to reduce the size of the dilator. The method may include, while the dilator has the reduced size, withdrawing the dilator through the enlarged opening.

In some examples, the heating includes flowing heated saline through the dilator via a catheter. In some examples, the heating includes applying radio frequency (RF) energy to the dilator. In some examples, the method includes deploying a device within the opening, and withdrawing the dilator through the device.

Under another aspect, a transatrial gate is provided. The transatrial gate may include a left atrial disc including a first self-expanding superelastic material, and a right atrial disc including a second self-expanding superelastic material. The transatrial gate also may include a martensitic shape-memory material that is heat set to completely occlude passage between the left and right atrial discs that is expandable to allow passage between the left and right atrial discs.

In some examples, the martensitic shape-memory material is provided as a mesh. In some examples, the martensitic shape-memory material is balloon expandable. In some examples, the martensitic shape-memory material is configured to be closeable by application of heat after being expanded to allow passage between the left and right atrial discs. The left atrial disc, the right atrial disc, and the martensitic shape memory material optionally are integrally formed from a common frame with one another.

Under another aspect, a method of performing a procedure is provided. The method may include implanting a transatrial gate through an opening in an atrial septum of a heart. The transatrial gate may include a left atrial disc including a first self-expanding superelastic material, and a right atrial disc including a second self-expanding superelastic material. The transatrial gate also may include a martensitic shape-memory material that is heat set to completely occlude passage between the left and right atrial discs. The method may include expanding the martensitic shape-memory material to allow passage between the left and right atrial discs.

In some examples, the material includes blood. In some examples, the material includes an instrument. In some examples, the method includes using the instrument to perform an additional procedure in a left atrium of the heart. In some examples, the additional procedure includes RF ablation, left atrial appendage closure, MitraClip implantation, mitral valve replacement, or mitral valve repair. In some examples, the martensitic shape-memory material is provided as a mesh. In some examples, the martensitic shape-memory material is expanded using a balloon. In some examples, the method further includes, after the expanding, closing the martensitic shape-memory material by application of heat. The left atrial disc, the right atrial disc, and the martensitic shape memory material optionally are integrally formed from a common frame with one another.

Under yet another aspect, an apparatus is provided. The apparatus includes a device that includes a proximal portion configured to be disposed in a first atrium of a heart, and a distal portion configured to be disposed in a second atrium of a heart and including a first self-expanding superelastic material. The device further includes an intermediate portion disposed between the proximal portion and the distal portion and configured to be disposed in an atrial septum between the first atrium and the second atrium. The intermediate portion includes a malleable shape-memory material. The apparatus further includes a catheter and at least one constricting flexible longitudinal element. The first self-expanding superelastic material may have a predetermined fully expanded dimension. The intermediate portion may have a first dimension suitable for deployment through the catheter, may be expandable to a second dimension for fixation within the septum, may be thermally transitionable to a third dimension, and may be mechanically re-expandable to a fourth dimension. The device may be removable by drawing the device into the catheter using the at least one constricting flexible longitudinal element.

In some examples, the proximal portion is flared. In some examples, the distal portion is flared. In some examples, the proximal portion includes a second self-expanding superelastic material. The proximal portion, the distal portion, and the intermediate portion optionally are integrally formed from a common frame with one another.

Under another aspect, a method is provided that includes through a catheter, deploying a device through an atrial septum of a heart. The device may include a proximal portion disposed in a first atrium of the heart, and a distal portion disposed in a second atrium of the heart and comprising a first self-expanding superelastic material. The device may include an intermediate portion disposed between the proximal portion and the distal portion and disposed in the atrial septum between the first atrium and the second atrium. The intermediate portion may include a malleable shape-memory material. The first self-expanding superelastic material may have a predetermined fully expanded dimension. The intermediate portion may have a first dimension when deployed through the catheter. The method may include expanding the intermediate portion to a second dimension for fixation within the septum. The method may include thermally transitioning the intermediate portion to a third dimension. The method may include mechanically re-expanding the intermediate portion to a fourth dimension. The method may include removing the device by drawing the device into the catheter using the at least one constricting flexible longitudinal element.

In some examples, the proximal portion is flared. In some examples, the distal portion is flared. In some examples, the proximal portion includes a second self-expanding superelastic material. The proximal portion, the distal portion, and the intermediate portion optionally are integrally formed from a common frame with one another.

