Patent Description:
The present disclosure relates generally to the field of ventricular assist devices. A ventricular assist device, or VAD, is a mechanical circulatory device that is used to partially or completely replace the function of a failing heart. Some VADs are intended for short term use, typically for patients recovering from heart attacks or heart surgery, while others are intended for long term use (months to years and in some cases for life), typically for patients suffering from congestive heart failure.

VADs are designed to assist either the right (RVAD) or left (LVAD) ventricle, or both at once (BiVAD). Which of these types is used depends primarily on the underlying heart disease and the pulmonary arterial resistance that determines the load on the right ventricle. In some applications a percutaneous RVAD to support the right heart must pump blood across the pulmonary valve.

<CIT> discloses pump and cannula systems inserted through the right side and/or left side of the heart which systems provide protection against collapse of the heart chambers and veins and arteries and provide supplemental blood flow through same to enable beating heart or still heart surgery, such as bypass surgery, on all vessels of the heart, including lateral and posterior vessels.

According to the invention, an apparatus and a method comprising the features of the respective independent claim are provided.

The inventors have realized that a cannula may be provided which closely matches the anatomy of the vast majority of patients and is suitable for use in a VAD device, e.g., an RVAD, Medical images (e.g., CT scans) of the hearts of one or more subjects may be analyzed, e.g., to determine the position of one or more anatomical landmarks. This analysis may be used to generate a cannula shape design (e.g., of the type described herein) that matches the anatomy of most patients.

In a first aspect, an apparatus is disclosed including: a cannula having a shape closely matched to the anatomy of the right ventricle of the human heart. In some embodiments, the cannula has an outflow port configured to be located proximal the pulmonary artery (PA) and an inflow port located proximal the inferior vena cava (IVC). In some embodiments, the cannula is configured to traverse the right atrium (RA), tricuspid valve (TV) and pulmonic valve (PV).

In some embodiments, the cannula includes: a primary section corresponding to the path from the diaphragm fibrous ring in the IVC to the IVC to RA transition (IVC-RA); a secondary section corresponding to the path from the IVC-RA to the TV; a tertiary section corresponding to the path from the TV to the PV; and a quaternary section corresponding to the path between the PV and the left branch of the pulmonary artery. In some embodiments, the primary section extends to the inflow port and the inflow port is configured to be located beyond the diaphragm fibrous ring of the IVC.

In some embodiments, the cannula includes: a first segment extending from a point A to a point B having the inflow port proximal point A; a second segment extending from a point B to a point C; a third segment extending from a point C to a point D; and a fourth segment extending from a point D to a point E, having the outflow port proximal point E. In some embodiments, the first, second and third segments lie substantially in a first plane containing points A, B, and C. In some embodiments, the forth segment lies substantially in a second plane containing points C, D, and E, the second plane being oriented to the first plane at an angle of about <NUM> degrees. In some embodiments, the first segment has a length of about <NUM>. In some embodiments, the second segment has a length of about <NUM>. In some embodiments, the third segment has a length of about <NUM>. In some embodiments, the fourth segment has a length of about <NUM>. In some embodiments, the second segment is oriented to the first segment at an angle of about <NUM> degrees in the first plane, with a bend radius of curvature of about <NUM>.

In some embodiments, the third segment is oriented to the first segment at an angle of about -<NUM> in the first plane, with a bend radius of curvature of about <NUM>. In some embodiments, the forth segment is oriented to the third segment at an angle of about -<NUM> degrees in the second plane, with a bend radius of curvature of about <NUM>.

Some embodiments include a pigtail extension extending from the end of the fourth segment at a point proximal point E, the pigtail extension lying substantially in a third plan oriented at an angle of about -<NUM> degrees to the second plane.

In some embodiments, the cannula is formed of a biocompatible material.

In some embodiments, the cannula is formed of a substantially rigid material.

In some embodiments, the cannula is formed of an at least partially flexible material.

The cannula includes a polyurethane tube reinforced with a surrounding coil of nitinol.

Some embodiments include a percutaneous ventricular assist device including the cannula, and including at least on pump located within the cannula.

In some embodiments, the cannula has a shape closely matched to the anatomy of at least <NUM>% of the adult human population, at least <NUM>% of the adult human population at least <NUM>% of the adult human population, or more.

In another aspect, a method is disclosed including forming a cannula of the type recited above.

In another (unclaimed) aspect, a method is disclosed including implanting an apparatus as recited above in a human heart.

In another aspect, a method including: receiving medical image data corresponding the anatomy of the right ventricle of each of a plurality of human subjects; processing the medical image data to determine landmark information indicative of the position of a plurality of anatomical landmarks; and generating a cannula design based on the landmark information. The method includes fabricating a cannula based on the cannula design.

In some embodiments, processing the medical image data to determine landmark information includes: for each of the plurality of human subjects, generating information indicative of a position of the IVC, RA, TV, PV and PA.

In some embodiments, the information indicative of the position of the IVC, RA, TV, PV and PA includes: a length and an angle between the IVC and the RA; a length and an angle between the RA and the TV; a length and an angle between the TV and PV; and a length and an angle between the PV and PA.

Some embodiments include: fabricating the cannula includes fabricating the cannula having a shape closely matched to the anatomy of the right ventricle of the human heart, where the cannula has an outflow port configured to be located proximal the PA and an inflow port located proximal the IVC.

In some embodiments, the cannula is configured to traverse the right atrium (RA), tricuspid valve (TV) and pulmonic valve (PV).

In some embodiments, the cannula includes: a primary section corresponding to the path from the diaphragm fibrous ring in the IVC to the IVC to RA transition (IVC-RA); a secondary section corresponding to the path from the IVC-RA to the TV; a tertiary section corresponding to the path from the TV to the PV; and a quaternary section corresponding to the path between the PV and the left branch of the pulmonary artery.

In some embodiments, the cannula has a shape closely matched to the anatomy of at least <NUM>%, <NUM>%, <NUM>%, <NUM>% or more of the adult human population.

In another aspect, a product is disclosed including: a cannula fabricated using any method recited above.

Each of the aspects and embodiments of the invention described herein can be used alone or in combination with one another.

The aspects and embodiments will now be described with reference to the attached drawings.

Referring to <FIG>, a catheter-based percutaneous VAD <NUM> for treatment of acute right heart failure is shown. As shown, the device inflow <NUM> resides in the inferior vena cava (IVC); a flexible cannula <NUM> traverses the right atrium (RA), tricuspid (TV) and pulmonic valves (PV), while the device outflow <NUM> resides in the pulmonary artery (PA). The cannula may house a drive system and pump, e.g., of the types used in VADs available under the Impella trade name from Abiomed, Inc of Danvers, MA. In some embodiments, the device provides flows of up to <NUM> Umin or more and up to <NUM> weeks of support or more.

The shape of cannula <NUM> closely matches the anatomy of the right ventricle of the human heart. For example, as described in greater detail below, the shape of the cannula may be based on a fit study of a population of subjects, e.g., using a library of medical images (e.g., CT or MRI scan images) of the subjects. In some embodiments, the cannula is a close fit to the anatomy of at least <NUM>%, <NUM>%, <NUM>%, <NUM>%, or more of a population (e.g., the adult human population, adult male human population, adult female human population, the human population for a given age range, etc.).

<FIG> show several perspective views of an embodiment of the RVAD cannula <NUM>. As shown in <FIG>, the cannula extends between the inflow port <NUM> and the outflow port <NUM> and includes primary, secondary, tertiary, and quaternary sections labeled <NUM>, <NUM>, <NUM>, and <NUM>, respectively.

Beginning at the inflow port <NUM>, the cannula <NUM> includes a substantially straight <NUM> primary section <NUM> extending between points A and B. The cannula <NUM> next includes a secondary section <NUM> extending from point B to point C. The secondary section <NUM> has a length of <NUM>. The angle formed between the primary and secondary sections <NUM>, <NUM> is <NUM> degrees, with a radius of curvature of <NUM>. (See <FIG>.

The secondary section <NUM> is followed by a tertiary section <NUM> extending from point C to point D. The tertiary section has a length of <NUM>. The angle formed between the secondary and tertiary sections is -<NUM> degrees, with a radius of curvature of <NUM>. (See <FIG>. ) he tertiary section <NUM> is followed by a quaternary section <NUM> extending from point D to point E. The quaternary section has a length of <NUM>. The angle formed between the tertiary and quaternary sections in the plane defined by points C-D-E is -<NUM> degrees, with a radius of curvature of <NUM>. (See <FIG>.

Note that the point E lies outside of the plane defined by points A-B-C. As shown in <FIG>, the plane defined by points A-B-C is oriented at an angle of <NUM> degrees to the plane define by points C-D-E.

In some embodiments, contiguous to the input port <NUM> of the cannula <NUM> is an extension <NUM> (e.g. of soft elastic material) that mechanically, yet not hydraulically extends the cannula <NUM>. In some embodiments, this extension <NUM> is provided with a pigtail tip <NUM> to allow for a traumatic support on body tissue. As shown in <FIG> , the pigtail tip <NUM> may be oriented at an angle of e.g., -<NUM> degrees from the plane defined by points C-D-E.

<FIG> is a table summarizing the above-described dimensions of an embodiment of the RVAD cannula shown in <FIG>. In various embodiments, the length, radius and/or angle dimensions may vary from the values given below by less that <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>% etc..

In various embodiments, the cannula <NUM> has an inner diameter in the range of <NUM>-<NUM>, e.g., <NUM> and an outer diameter of <NUM>-<NUM>, e.g., <NUM>. In some embodiments, other suitable dimensions may be used. The cannula may be constructed of any suitable biocompatible material. The material may be substantially rigid or at least partially flexible. In the embodiment according to the invention, the cannula is constructed of a polyurethane tube reinforced with a coil of nitinol. In other examples (not claimed), the coil can be made of other suitable material, e.g., a material featuring shape memory. In some embodiments, the polyurethane material may include the material having the trade name Desmopan <NUM>, available from Bayer Material Science AG of Leverkusen, Germany.

The cannula <NUM> may be fabricated using any techniques know in the art including, e.g., molding, injection molding, etc..

As noted above, the cannula <NUM> is designed to closely match the anatomy of the right ventricle. In some embodiments, each section of the cannula is designed to extend between the expected locations of various anatomical landmarks (e.g., as determined based on the average location of these landmarks found using an anatomical fit study). For example, in the embodiments described above, the primary section <NUM> corresponds to the path from the diaphragm fibrous ring in the IVC to the IVC to RA transition (IVC-RA). The secondary section <NUM> corresponds to the path from the IVC-RA to the TV. The tertiary section <NUM> corresponds to the path from the TV to the PV. The quaternary section <NUM> corresponds to the path between the PV and the left branch of the PA. As shown, the length of the primary section <NUM> is chosen such that the inflow port <NUM> is located beyond the diaphragm fibrous ring. As shown, the length of the quaternary section <NUM> is chosen such that the outflow port <NUM> is located at the left PA bifurcation, with extension <NUM> residing in the left PA. It is to be understood that, in other embodiments, any other suitable choice of landmarks may be used. To ensure a cannula shape which conforms to the anatomy of a wide range of patients, it is advantageous to select a set of landmarks having relative locations which exhibit low patient-to-patient variability do not depend strongly on the size of the patient (e.g., as determined by the patients body surface area (BSA)). As discussed in greater detail below, the landmarks described above meet both of these criteria.

In various embodiments, the RVAD device <NUM> includes the cannula <NUM> described above enclosing one or more pumps and pump motor drives (not shown). Any suitable pump and/or drive known in the art may be used. In some embodiments, the cannula may be a component of a BiVAD device.

In some embodiments the RVAD is advantageously small, with a low blood-wetted surface area, e.g., of <NUM><NUM> or less, <NUM><NUM> or less, <NUM><NUM> or less, <NUM><NUM> or less, <NUM><NUM> or less, etc. (e.g., in the range of <NUM>-<NUM><NUM>).

In some embodiments the cannula may be introduced into the ventricle using a catheter based technique, e.g., of the types described in Cannula Systems and Methods of Use, <CIT>.

<FIG> illustrates a process <NUM> for designing and producing a cannula of the type described herein. In step <NUM>, medical image data (e.g., including 3D CT or MRI scans of the hearts of a set of patients) is received or obtained (e.g., from a database).

In step <NUM>, a set of anatomical landmarks is selected (e.g., the landmarks described with reference to <FIG> above). To ensure a cannula shape which conforms to the anatomy of a wide range of patients, it is advantageous to select a set of landmarks having relative locations which exhibit low patient-to-patient variability do not depend strongly on the size of the patient (e.g., as determined by the patients body surface area (BSA)).

In step <NUM>, the image data is analyzed to locate the anatomical landmarks and determine information about their relative (and/or absolute) positions. The landmarks may be identified automatically (using any image processing or machine vision techniques known in the art), manually (e.g., by presenting the images to a medical practitioner for examination), or combinations thereof. Average positions for the landmarks may be determined over a sample population of patients In step <NUM>, a cannula design is generated based on the analysis performed in step <NUM>. For example, the size and/or orientations of various sections of the cannula may be determined based on the average positions for the landmarks over a sample population of patients, in order to provide a cannula design which closely matches the anatomy of the heart over a large range of patients. The cannula design may be output (e.g., as a data file containing a listing a parameters, a computer aided design (CAD) file, etc.).

In step <NUM>, the cannula is produced based on the cannula design generated in step <NUM>. As described above, the cannula may be fabricated using any suitable technique know in the art.

The following sets for one non-limiting example of a cannula design.

Nineteen representative 3D CT scans of the hearts of patients having BSA ranging from <NUM>-<NUM><NUM> were used to optimize cannula geometry using the techniques described herein. Lengths and angles between the IVC, RA, TV, PV and PA were measured using Mimics software (available from Materialise NV, Belgium).

The results of the study are summarized in <FIG>. Standard deviations for the length and angles were <NUM> and <NUM> degrees, showing low patient-to-patient variability. Further, as shown in <FIG>, no correlation with BSA (body surface area) was found. Considerations were made for the out-of-plane nature of the TV, while placement of the device outflow at the L bifurcation of the PA resulted in a 3D cannula configuration, as described in detail above with reference to <FIG> and <FIG>.

The optimized cannula design was found to fit in <NUM>% or more of patients assuming a rigid cannula, and would fit as much as <NUM>% of patients allowing for cannula flexibility. Additional cadaver fit studies were performed which validated the computational modeling.

Although several specific example have been shown of devices for used in the right ventricle in an adult human heart, it is to be understood that the devices and techniques described herein may be extended to other anatomical locales (e.g. the left ventricle) and/or to other types of subjects, e.g., non-human animal subjects.

The above-described embodiments can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers.

Further, it should be appreciated that a computer may be embodied in any of a number of forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embedded in a device not generally regarded as a computer but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smart phone or any other suitable portable or fixed electronic device.

Such computers may be interconnected by one or more networks in any suitable form, including a local area network or a wide area network, such as an enterprise network, and intelligent network (IN) or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks or fiber optic networks.

A computer employed to implement at least a portion of the functionality described herein may comprise a memory, one or more processing units (also referred to herein simply as "processors"), one or more communication interfaces, one or more display units, and one or more user input devices. The memory may comprise any computer-readable media, and may store computer instructions (also referred to herein as "processor-executable instructions") for implementing the various functionalities described herein. The processing unit(s) may be used to execute the instructions. The communication interface(s) may be coupled to a wired or wireless network, bus, or other communication means and may therefore allow the computer to transmit communications to and/or receive communications from other devices. The display unit(s) may be provided, for example, to allow a user to view various information in connection with execution of the instructions. The user input device(s) may be provided, for example, to allow the user to make manual adjustments, make selections, enter data or various other information, and/or interact in any of a variety of manners with the processor during execution of the instructions.

The various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and/or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.

In this respect, various inventive concepts may be embodied as a computer readable storage medium (or multiple computer readable storage media) (e.g., a computer memory, one or more floppy discs, compact discs, optical discs, magnetic tapes, flash memories, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other non-transitory medium or tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments of the invention discussed above. The computer readable medium or media can be transportable, such that the program or programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present invention as discussed above.

The terms "program" or "software" are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of embodiments as discussed above. Additionally, it should be appreciated that according to one aspect, one or more computer programs that when executed perform methods of the present invention need not reside on a single computer or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present invention.

Also, various inventive concepts may be embodied as one or more methods, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section <NUM>.

Claim 1:
An apparatus comprising:
a cannula (<NUM>) having a shape closely matched to the anatomy of the right ventricle of the human heart, wherein the cannula (<NUM>) has an outflow port (<NUM>) configured to be located proximal the pulmonary artery (PA) and an inflow port (<NUM>) located proximal the inferior vena cava (IVC), characterized in that the cannula (<NUM>) comprises a polyurethane tube reinforced with a surrounding coil of nitinol.