Patent Description:
The present invention relate to an apparatus for testing the flexibility of prosthetic leaflets to be used in prosthetic heart valves.

Prosthetic heart valves may be constructed of a frame to which prosthetic leaflets are attached, the leaflets providing check-valve functionality by opening in response to blood flow in a first direction, and closing in response to blood flow in a second direction. In order to inhibit leakage ("regurgitation") of blood between the closed leaflets in the second direction, it is important that the leaflets coapt well against each other. One factor facilitating coaptation of leaflets in a prosthetic heart valve is flexibility of.

<CIT> and <CIT> both describe an apparatus for testing a prosthetic heart valve leaflet on a vertical mount, wherein each leaflet is separately tested.

The present invention is directed to determining flexibility of prosthetic heart valve leaflets. Sorting leaflets into groups or categories of similarly flexible leaflets (e.g., to be sewn together in a prosthetic heart valve) may facilitate the preparation of properly functioning prosthetic heart valves.

Aspects of the present invention include apparatus for computationally assigning values indicative of leaflet flexibility to leaflets, by digital analysis of an image including a plurality of leaflets draped over a plurality of bars.

Some aspects of the present invention include sorting the leaflets into leaflet categories, each leaflet category being characterized by the at least one value indicative of leaflet flexibility.

Other aspects of the present invention include grouping leaflets into groups in response to similarity, for each leaflet grouped into a group, of at least one value indicative of leaflet flexibility.

There is therefore provided, in accordance with an application of the present invention, apparatus for testing a plurality of prosthetic heart valve leaflets, the apparatus including:.

In an application, the mount is generally flat, and the plurality of horizontal bars are generally parallel with each other.

In an application, the mount is concave toward the image sensor.

In an application, the apparatus includes exactly one image sensor.

In an application, the apparatus includes an image output device configured to transmit the image.

In an application, the apparatus includes a sensor-bracket that movably couples the image sensor to the mount, such that the image sensor is movable along a sensor-axis with respect to the mount.

In an application, the apparatus includes circuitry, configured to receive the image, and to analyze the image, the analysis of the image being such that, for each of the leaflets included in the image, the circuitry derives a corresponding flexibility value that is indicative of flexibility of the leaflet.

In an application, the circuitry is configured to, for each of the leaflets, identify a draping-contour line, and to derive the value at least in part responsively to an Area Under Curve value defined by the draping-contour line.

In an application, the circuitry is configured to assign a respective flexibility category to each of the leaflets, responsively to the flexibility value.

In an application, the apparatus includes at least one indicator that is in communication with the circuitry, the indicator configured to indicate the respective category assigned to each leaflet.

In an application, the apparatus includes a respective indicator for each of the leaflets, each of the indicators being configured to indicate the respective category assigned to the respective leaflet.

In an application, each of the indicators is disposed adjacent to the respective bar that supports the respective leaflet.

In an application, the circuitry is configured:.

In an application, the circuitry is configured to identify the first-leaflet-tip and the second-leaflet tip, and to derive the value at least in part responsively to a first-leaflet-tip position of the first leaflet tip and a second-leaflet-tip position of the second leaflet tip.

In an application, the circuitry is configured to derive the value at least in part responsively to a vertical height of the first-leaflet-tip position and a vertical height of the second-leaflet-tip position.

In an application, the circuitry is configured to derive the value at least in part responsively to a horizontal location of the first-leaflet-tip position and a horizontal location of the second-leaflet-tip position.

In an application, the circuitry is configured to derive the value at least in part responsively to:.

In an application, the circuitry is configured to derive the value at least in part responsively to a direct distance between the first-leaflet-tip position and the second-leaflet-tip position.

In an application, the circuitry is configured to group the leaflets into groups, based on similarity between (i) the flexibility value of each leaflet of the plurality of leaflets, and (ii) the respective flexibility value of other leaflets of the plurality of leaflets, each of the groups including a predetermined number of leaflets.

In an application, the predetermined number of leaflets in each group is two leaflets.

In an application, the predetermined number of leaflets in each group is three leaflets.

In an application, the apparatus includes at least one indicator that is in communication with the circuitry, the indicator configured to indicate the respective group to which each leaflet is grouped.

In an application, the apparatus includes a respective indicator for each of the leaflets, each of the indicators being configured to indicate the respective group to which each leaflet is grouped.

In an application, the apparatus includes:.

In an application, the bar has an initial position with respect to the platform, in which the leaflet is placeable across the bar such that the leaflet is in contact with the surface.

In an application, in the initial position, the bar is disposed below the surface.

In an application, the platform has a guide that defines a guide-outline that corresponds to a leaflet-outline of the leaflet, such that when the leaflet is placed on the surface with the leaflet-outline aligned with the guide-outline, the leaflet is disposed across the bar.

In an application, the platform is disposed with respect to the bar such that the bar-plane bisects the guide-outline.

In an application, the platform is disposed with respect to the bar such that the bar-plane bisects the guide-outline symmetrically.

In an application, the surface of the guide is at least partially included of a low-friction material.

In an application, the low-friction material is Teflon.

In an application, the bars extend away from the mount in parallel with each other.

In an application, the bars are arranged, with respect to the mount, in multiple rows and multiple columns.

In an application, the mount is a strong color.

Reference is made to <FIG>, <FIG>, and <FIG>, which are schematic illustrations showing a tester <NUM> for testing flexibility of a plurality of prosthetic heart valve leaflets, in accordance with some applications of the invention. <FIG> are perspective views of tester <NUM> in a first state and an elevated state, respectively. <FIG> is a perspective view of an alternative embodiment of tester <NUM>. <FIG> are side, front, and top views, respectively, of tester <NUM> in the first state.

Tester <NUM> comprises a plurality of horizontal bars <NUM> movably coupled to a vertical mount <NUM>, in accordance with some applications of the invention. Typically, and as shown, each bar <NUM> extends away from mount <NUM> (e.g., perpendicularly from the mount) along a respective bar-axis D26, each bar-axis lying on a respective vertical bar-plane D28.

Tester <NUM> has a first state (<FIG>, <FIG>) and an elevated state (<FIG>). For some applications, and as shown, bars <NUM> are cylindrically shaped. For other applications, bars <NUM> may be of an alternate shape (e.g., rectangular prism, hexagonal prism or octagonal prism). Typically, actuation of an actuator <NUM> reversibly transitions tester <NUM> between the first state and the elevated state. Actuator <NUM> is shown as a manually-operated (e.g., mechanical) actuator. For some applications (<FIG>), an electrical (e.g., motorized) actuator <NUM> may be used instead.

As shown in <FIG>, transitioning of tester <NUM> between the first and elevated states includes vertical motion of each bars <NUM> along its vertical bar-plane D28 with respect to a platform <NUM>. Typically, actuator <NUM> moves bars <NUM> upward with respect to the rest of tester <NUM>, and platform <NUM> remains stationary. However, the actuator <NUM> is moving platform <NUM> downward with respect to the rest of tester <NUM>, while bars <NUM> remain stationary. Typically, and as shown, the platform is coupled to mount <NUM> such that each bar-plane D28 intersects the platform.

Tester <NUM> further comprises an image sensor <NUM>, the image sensor positioned opposite mount <NUM>, facing bars <NUM> and the mount. Orientation of image sensor <NUM> facing mount <NUM> and bars <NUM> facilitates the image sensor acquiring an image that includes leaflets <NUM> (e.g., all of the leaflets) draped over bars <NUM>. Typically, and as shown, tester <NUM> further comprises a sensor-bracket <NUM>, the sensor-bracket movably coupling image sensor <NUM> to the rest of tester <NUM> (e.g., to mount <NUM>). Typically, sensor-bracket facilitates movement of image sensor <NUM> along a sensor-axis D38, moving the image sensor toward and away from mount <NUM>. Sensor-bracket <NUM> typically facilitates movement of image sensor <NUM> (e.g., along sensor-axis D38) between (i) a position in which the image sensor can acquire an image that includes all of leaflets <NUM>, and (ii) a position in which tester <NUM> is more compact - e.g., for when the tester is not in use. Typically, tester <NUM> is operated such that sensor <NUM> acquires an image that includes the multiple leaflets draped over bars <NUM>. It is hypothesized by the inventors that acquiring and processing an image that includes multiple leaflets increases work throughput and/or improves accuracy of leaflet flexibility testing.

Typically, and as shown, mount <NUM> is generally flat, and bars <NUM> are generally parallel with each other. For some applications, mount <NUM> may be concave toward sensor <NUM>, and bar-tips are arranged correspondingly to the concave surface of the mount, e.g., pointing toward the sensor. It is hypothesized by the inventors that, for some applications, mount <NUM> being concave may facilitate visualization of all leaflets <NUM> and bar-tips <NUM>, from a single point of view - i.e., by sensor <NUM>.

Some embodiments of the invention may comprise a plurality of image sensors <NUM>. For example, the number of image sensors <NUM> may correspond to the number of bars <NUM>.

Reference is made to <FIG>, which are schematic illustrations showing the arrangement of platform <NUM> with respect to bars <NUM> and mount <NUM>, in accordance with some applications of the invention. Typically, and as shown, bars <NUM> extend away from mount <NUM> in parallel with each other. For some applications, and as shown, bars <NUM> are arranged, with respect to the mount, in multiple rows <NUM> and multiple columns <NUM>. For some applications in which bars <NUM> are arranged in multiple rows (i.e., such that bars <NUM> are stacked in at least one column), bars <NUM> may be arranged with respect to mount <NUM> such that the bar-planes D28 of the bars in a given column are coplanar - i.e., are disposed in a common bar-plane D28 - as shown. Although the Figures referred to herein depict an embodiment of tester <NUM> with bars <NUM> arranged in three rows <NUM> and three columns <NUM>, this depiction is not intended to exclude other possible arrangements with either a smaller or greater number of rows <NUM> or columns <NUM> of bars <NUM>. For some applications, and as shown, nine bars <NUM> may be arranged in rows <NUM> and columns <NUM> such that image sensor <NUM> may acquire an image including nine leaflets <NUM>, each leaflet draped over a respective bar. For other applications, tester <NUM> may comprise a greater or lesser number of bars <NUM> arranged with respect to mount <NUM>, mutatis mutandis. For some applications, the number of bars <NUM> is a multiple of <NUM>, e.g., such that all of the leaflets being tested in a single batch may be divided into groups of <NUM> matching leaflets, each group being used in a respective tri-leaflet prosthetic valve.

Typically, and as shown, platform <NUM> has an upper surface <NUM>, the upper surface including a guide <NUM> that defines a guide-outline <NUM> corresponding to a leaflet-outline <NUM> of leaflet <NUM>. In some applications, upper surface <NUM> at guide <NUM> may comprise a low-friction material. For example, the low-friction material may comprise polytetrafluoroethylene (e.g., Teflon (TM)). Alternatively or additionally, the texture of upper surface <NUM> may be modified at guide <NUM>. For example, the texture of upper surface <NUM> may be made to be more smooth (e.g., polished) at guide <NUM>. The use of low-friction material and/or texture for upper surface <NUM> of guide <NUM> is hypothesized by the inventors to facilitate release of leaflet <NUM> from the surface as bar <NUM> lifts the leaflet away from the surface, thereby facilitating use of tester <NUM>.

Reference is further made to <FIG>, which are schematic illustrations showing lifting of bars <NUM> such that each bar supports leaflet <NUM>, with the leaflet draped over the bar, in accordance with some applications of the invention. Typically, and as shown, bar <NUM> has an initial position (<FIG>) with respect to platform <NUM>, in which leaflet <NUM> may be placeable across the bar such that the leaflet is in contact with upper surface <NUM>, and surface <NUM> supports the leaflet, e.g., in a flat configuration (<FIG>). For example, in the initial position, bar <NUM> may be disposed below upper surface <NUM>.

For some applications, leaflets <NUM> are non-isotropically flexible. For example, a leaflet may have a first flexibility when draped over bar <NUM> with a first side of the leaflet facing up, and a different flexibility when draped over the bar with the opposite side of the leaflet facing up. For such applications, leaflets <NUM> are typically draped over bars <NUM> such that they bend in the orientation in which they will bend when in use. Typically, the side of the leaflet that faces up on tester <NUM> is the side of the leaflet that will face upstream in the functioning prosthetic valve.

For example, leaflets <NUM> may comprise pericardium that has distinct sides (e.g., a rough side and a smooth side). For such applications, the rough side typically faces upstream in the functioning prosthetic valve. Therefore, for such applications, it may be desirable to orient leaflets <NUM> upon respective guides <NUM> with the rough side facing upwards, such that, upon actuation of actuator, each leaflet will drape over respective bar <NUM> with the rough side facing upwards. Alternatively, it may be desirable to orient leaflets <NUM> upon respective guides <NUM> with the smooth side facing upwards, such that, upon actuation of actuator, each leaflet will drape over respective bar <NUM> with the smooth side facing upwards. It is hypothesized by the inventors that uniform orientation of leaflets <NUM> upon guide <NUM> may increase the relevance of leaflet flexibility testing to the performance of the leaflets in the prosthetic valve.

Typically, platform <NUM> is disposed with respect to bar <NUM> such that bar-plane D28 bisects guide-outline <NUM> (<FIG>). Further typically, and as shown, platform <NUM> is disposed with respect to bar <NUM> such that bar-plane D28 bisects guide-outline <NUM> symmetrically. As shown in <FIG>, in the elevated state of tester <NUM>, each bar <NUM> supports the respective leaflet <NUM> along the respective bar-axis D26 such that the leaflet drapes over the bar.

For some applications, mount <NUM> may have a strong color. For some applications, bar-tip <NUM> may have a second strong color. For some applications, platform <NUM> may have a third strong color. For example, a platform face <NUM> of platform <NUM> may have the third strong color. It is to be noted that the term "strong color" (including the specification and the claims) relates to color saturation. For example, primary colors may serve as the strong colors. The use of respective strong colors for mount <NUM>, bar-tip <NUM> and/or platform face <NUM> is hypothesized to facilitate analysis of the image by facilitating distinction between these components and leaflet <NUM>, and between these components and each other.

Reference is made to <FIG>, which are schematic illustrations showing use of tester <NUM>, in accordance with some applications of the invention.

As described hereinabove, image sensor <NUM> acquires an image that includes the plurality of leaflets <NUM> draped over their respective bars.

In some applications (e.g., those shown in <FIG>), circuitry <NUM>, configured to receive the image, is coupled to (e.g., mounted on) tester <NUM>. Typically, circuitry <NUM> is further configured to analyze the image, such that, for each leaflet <NUM> included in the image, the circuitry derives a corresponding flexibility value that is indicative of flexibility of the leaflet. Derivation of the flexibility value is described in more detail hereinbelow.

For some applications, circuitry <NUM> is not mounted on tester <NUM>. For such embodiments, tester <NUM> may include an image output device (e.g., a port or wireless transceiver) <NUM> (<FIG>). Typically, output device <NUM> is configured to interface with a distinct computer <NUM> (e.g., a general-purpose computer), and therefore device <NUM> typically operates according to a recognized standard, such as USB or Bluetooth. For such applications, software is provided to be run on computer <NUM>, and therefore the circuitry of the computer serves as circuitry <NUM>.

For some applications, and as described in more detail hereinbelow, circuitry <NUM> is further configured to assign a category to each of the leaflets, in response to the flexibility value. Typically, and as shown in <FIG>, tester <NUM> includes at least one indicator <NUM> that is in communication with circuitry <NUM>, and indicates the respective category assigned to each leaflet <NUM>. For some applications, tester <NUM> comprises a single indicator (e.g., a display) that indicates the categories of all of the leaflets (e.g., as shown in <FIG>). For other applications, tester <NUM> comprises a respective indicator <NUM> for each leaflet <NUM>, the indicator configured to indicate the category assigned to the leaflet. For example, indicator <NUM> may be disposed adjacent to the respective bar <NUM> that supports the respective leaflet <NUM> (e.g., as shown in <FIG>). For applications in which a distinct computer receives the image and derives the value, the computer (e.g., a display of the computer) also serves as the indicator that indicates the categories (e.g., as shown in <FIG>).

For some applications, circuitry <NUM> is pre-programmed with a calibration routine, such that all leaflets <NUM> included in the image acquired by sensor <NUM> are correctly analyzed, e.g., despite each leaflet being disposed at a different position with respect to the image sensor. For some applications, the calibration routine includes acquiring an image that includes all bar-tips <NUM>, and analyzing the image in order to determine a position of sensor <NUM> with respect to the plurality of bars. For some such applications, the calibration routine is performed automatically, e.g., using the same image that includes the plurality of leaflets, which will be analyzed by circuitry <NUM> to derive their respective flexibility values, as described hereinbelow.

For some applications, sensor-bracket <NUM> comprises an electronic actuator, with which circuitry <NUM> may interface in order to move image sensor <NUM> (e.g., along sensor-axis D38). For some such applications, this movement is used to facilitate the calibration routine. The calibration of image sensor <NUM> may adjust a field of view of image sensor <NUM> such that the image sensor acquires an image that includes all leaflets <NUM>.

Reference is made to <FIG>, <FIG> and <FIG>, which are schematic illustrations showing image parameters that may be calculated by circuitry <NUM> in order to derive a flexibility value, in accordance with some applications of the invention. Circuitry <NUM> typically derives flexibility values for leaflets <NUM> by digitally analyzing the image acquired by sensor <NUM>. Circuitry <NUM> may derive the flexibility values in response to a single image parameter, or a combination of image parameters, e.g., as described hereinbelow.

<FIG> shows a leaflet 30a that has high flexibility. <FIG> shows a leaflet 30b that has moderate flexibility. <FIG> shows a leaflet 30c that has low flexibility.

As described hereinabove, bars <NUM> are configured to support leaflet <NUM> along bar-axis D26 such that the leaflet drapes over the bar. As shown, a first-leaflet-tip <NUM> is disposed below the bar on a first side <NUM> of the bar, and a second-leaflet-tip <NUM> is disposed below the bar on a second side <NUM> of the bar. For example, first-leaflet-tip <NUM> may be a lowest part of leaflet <NUM> on first side <NUM>, and second-leaflet-tip <NUM> may be a lowest part of leaflet <NUM> on second side <NUM>. In some applications, circuitry <NUM> is configured to identify, in the acquired image, first-leaflet-tip <NUM> and second-leaflet tip <NUM>, and to derive the leaflet-flexibility value at least in part responsively to a first-leaflet-tip position D96 of first leaflet tip <NUM> and a second-leaflet-tip position D98 of second leaflet tip <NUM>.

Image parameters that are calculated by circuitry <NUM> to derive leaflet-flexibility values may include one or more of the following:.

The use of a plurality of image parameters to derive leaflet-flexibility values is hypothesized by the inventors to more accurately reflect leaflet flexibility than may be derived from a single parameter. For example, a low AUC may alternatively indicate either a highly flexible or highly inflexible leaflet. The integration of AUC with direct distance D82 between first-leaflet-tip position D96 and second-leaflet-tip position D98 may aid in deriving a leaflet-flexibility value that more accurately reflects the leaflet's flexibility.

In some applications, leaflet-flexibility values may be used to facilitate sorting of the leaflets into categories of leaflet flexibility. For example, high-flexibility leaflet 30a may be assigned by tester <NUM> (e.g., circuitry <NUM> thereof) to a flexibility category "<NUM>", moderate-flexibility leaflet 30b may be assigned to a flexibility category "<NUM>", and low-flexibility leaflet 30c may be assigned to a flexibility category "<NUM>" - and the user may sort the leaflets according to the assigned categories. As described hereinabove, the category for each leaflet is typically indicated by indicator <NUM>, e.g., as shown in <FIG>.

For some applications, the user may sort leaflets <NUM> according to the assigned category - e.g., into receptacles corresponding to each flexibility category. Leaflets <NUM> may also be assigned to a "retest" category, or a "discard" category, e.g., as described herein below. Typically, the process is a batch process, in which multiple leaflets are placed on tester <NUM>, tested, and then sorted.

Leaflets that are assigned to the "retest" category may be resituated within the same or a different guide <NUM> for retesting (e.g., in the subsequent batch). Alternatively, leaflets <NUM> assigned to a "retest" category may be collected into a "retest" receptacle for subsequent retesting (e.g., in a dedicated retesting batch).

Reference is also made to <FIG>, which are graphs representing a relationship between leaflet-flexibility values of a set of leaflets <NUM>, and the leaflet-flexibility categories or groups to which the same leaflets are assigned, in accordance with some applications of the invention. As described hereinabove, for some applications leaflets <NUM> are assigned to leaflet-flexibility categories, based upon leaflet-flexibility values. Leaflet-flexibility categories are typically categorical variables. For example, the categories may be named categories "<NUM>", "<NUM>" and "<NUM>", e.g., as described hereinabove. Leaflet-flexibility values are typically continuous numerical variables. For example, leaflet-flexibility values may span a range from <NUM> to <NUM>, as shown.

Typically, and as shown, each leaflet flexibility category is defined by threshold leaflet-flexibility values, each threshold leaflet-flexibility value lying at a respective extreme of the category, such that each category includes leaflets with values spanning a range between the upper and lower thresholds of the category. For example, <FIG> shows category <NUM> spanning a range D148 of flexibility values, category <NUM> spanning a range D146 of flexibility values, and category <NUM> spanning a range D144 of flexibility values. Solid vertical lines represent the thresholds dividing between the leaflet-flexibility categories. For example, category "<NUM>" spans a range of leaflet-flexibility values between threshold D106 and threshold D112 ranging between <NUM> and <NUM>, category "<NUM>" spans a range of leaflet-flexibility values between threshold D112 and threshold D118 ranging between <NUM> and <NUM>, and category "<NUM>" spans a range of leaflet-flexibility values between threshold D118 and threshold D124 ranging between <NUM> and <NUM>.

It is to be noted that the leaflet-flexibility values and leaflet-flexibility category thresholds shown in <FIG> are for illustrative purposes only. The values, ranges, and thresholds are arbitrary, and are not intended to exclude alternate leaflet-flexibility values, ranges, or thresholds.

In <FIG>, hollow circles <NUM>, <NUM> and <NUM> represent three leaflets that would be assigned to leaflet-flexibility category <NUM>, having leaflet-flexibility values spanning a range from <NUM> to <NUM>; hollow circles <NUM>, <NUM> and <NUM> represent three leaflets that would be assigned to leaflet-flexibility category <NUM>, having leaflet-flexibility values spanning a range from <NUM> to <NUM>; and hollow circles <NUM>, <NUM> and <NUM> represent three leaflets that would be assigned to leaflet-flexibility category <NUM>, having leaflet-flexibility values spanning a range from <NUM> to <NUM>.

It is hypothesized by the inventors that assigning leaflets <NUM> to flexibility categories may enable efficient sorting of leaflets by their flexibility values. However, for some applications, sorting leaflets purely by such a categorization technique may result in leaflets that do not necessarily have the most similar flexibility values, being sorted into the same category. For instance, <FIG> shows the flexibility value of leaflet <NUM> (which would be categorized into category "<NUM>") to be closest to that of leaflets <NUM> and <NUM> (which would be categorized into category "<NUM>"). This potential obscuring of the similarity between leaflets in different categories due to their similar flexibility values being on different sides of a category threshold value is referred to herein as "threshold artifact. " Alternative or complimentary strategies to account for threshold artifact when assigning leaflets to flexibility categories, are described below.

For some applications, circuitry <NUM> is configured to refer certain leaflets <NUM> for manual assignment (e.g., by a human specialist) to flexibility categories. For some applications, circuitry <NUM> may designate leaflets <NUM> with flexibility values that are particularly close to the threshold values, to transition categories. For example, circuitry <NUM> may be configured such that each threshold has a margin, and leaflets whose flexibility values fall within a margin of a threshold are assigned to a transition category. <FIG> further shows dotted vertical margin lines demarcating margins of respective thresholds: D108 demarcates an upper margin <NUM> of threshold D106, D110 demarcates a lower margin of threshold D112, D114 demarcates an upper margin <NUM> of threshold D106, D116 demarcates a lower margin of threshold D118, D120 demarcates an upper margin of threshold D118, and D122 demarcates a lower margin of threshold D124. For example, in <FIG> the leaflets represented by symbols <NUM>, <NUM>, and <NUM> fall within such margins, and are therefore designated to transition categories. Leaflets designated to transition categories, referred to as "transition category leaflets" (e.g., category "<NUM>-<NUM>", category "<NUM>-<NUM>", or category "<NUM>-x"), may then be referred to a person (e.g., a specialist) in order to be assigned manually to a flexibility category.

For some applications, and as shown, circuitry <NUM> is not configured with a lower margin for threshold D106 and/or an upper margin of threshold D124. For some such applications, leaflets whose flexibility value falls below threshold D106 or above threshold D124 are referred to a person in order to be manually assessed (e.g., to be manually assigned to a flexibility category). For some such applications, such leaflets are automatically assigned to the corresponding "discard" category "x" or "y", e.g., to increase efficiency by reducing the likelihood of an unsuitable leaflet being referred to a specialist for manual categorization. For some such applications, leaflets whose flexibility value falls below threshold D106 are referred to a person in order to be manually assessed, whereas leaflets whose flexibility value falls above threshold D124 are automatically assigned to the corresponding "discard" category. For some such applications, leaflets whose flexibility value falls above threshold D124 are referred to a person in order to be manually assessed, whereas leaflets whose flexibility value falls below threshold D106 are automatically assigned to the corresponding "discard" category.

Alternatively, circuitry <NUM> is configured with a lower margin for threshold D106 and/or an upper margin of threshold D124, e.g., similarly to the margins of the other thresholds.

For some applications, tester <NUM> may simply indicate that a particular leaflet requires manual categorization. For some applications, tester <NUM> may facilitate manual categorization by indicating the categories between which the leaflet's flexibility value falls. For example, indicator <NUM> of tester <NUM> may display "<NUM>-<NUM>" for a leaflet whose flexibility value falls within margin <NUM> of the lower threshold of category <NUM> or within margin <NUM> of the upper threshold of category <NUM>.

For some applications, transition category leaflets may be designated to be tested a second time. It is hypothesized by the inventors that: <NUM>) manual assignment of transition category leaflets to flexibility categories, and/or <NUM>) retesting of transition category leaflets, may increase the validity and clinical utility of leaflet flexibility categories to which leaflets <NUM> are assigned.

For some applications, leaflets may be grouped by circuitry <NUM> and/or by user according to similarity of flexibility values, e.g., without the use of flexibility categories. Leaflets <NUM> of the same group may then be included together in an individual prosthetic heart valve. Circuitry <NUM> may therefore group leaflets <NUM> into groups of a desirable size (e.g., groups of two leaflets for a bileaflet valve, or groups of three leaflets for a trileaflet valve). For example, in <FIG>, ovals <NUM> and <NUM> indicate such grouping. Oval <NUM> indicates a group of three leaflets (<NUM>, <NUM> and <NUM>), which would all have been assigned to the same category (category <NUM>) had the categorization technique had been used (e.g., as shown in <FIG>). In this case, grouping these three leaflets <NUM> according to similarity of their respective leaflet-flexibility values would yield a similar result to that of sorting the leaflets into leaflet-flexibility categories.

That is, for some applications of the invention, tester <NUM> (e.g., circuitry <NUM> thereof) is configured to group leaflets <NUM> (e.g., all of the leaflets that are on tester <NUM>) into groups, based on similarity between (i) the flexibility value of each leaflet of the plurality of leaflets, and (ii) the flexibility value of other leaflets of the plurality of leaflets, each of the groups including a predetermined number of leaflets.

In contrast, oval <NUM> indicates a group of three leaflets (<NUM>, <NUM> and <NUM>), in which two of the leaflets (<NUM> and <NUM>) would have been assigned to one category (category <NUM>), and one of the leaflets (<NUM>) would have been assigned to a different category (category <NUM>), had the categorization technique had been used (e.g., as shown in <FIG>). Grouping these three leaflets <NUM> be included together in an individual prosthetic heart valve would yield a prosthetic heart valve with leaflets having more similar leaflet-flexibility values than would a prosthetic heart valve with leaflets sorted into category <NUM> or into category <NUM>.

Reference is also made to <FIG>, which is a schematic illustration of tester <NUM> using leaflet-flexibility values to group leaflets <NUM>, in accordance with some applications of the invention. <FIG> shows leaflets <NUM> draped over bars <NUM>, and indicators <NUM> indicating the grouping of leaflets into groups "A", "B" and "C" according to similarity of their respective leaflet-flexibility values. In the example shown, the simultaneous testing of nine leaflets, and the grouping of nine leaflets into three groups, may enable the construction of three trileaflet prosthetic heart valves, from each testing session. In the example shown, one trileaflet valve would be constructed from the three leaflets in group A, one trileaflet valve from those in group B, and one trileaflet valve from those in group C. It is hypothesized by the inventors that grouping leaflets <NUM> with similar leaflet-flexibility values (e.g., to be sewn together in a prosthetic heart valve) may facilitate the preparation of properly functioning prosthetic heart valves.

For some applications, leaflets <NUM> are first assigned to categories, and subsequently grouped into groups. For such applications, (i) leaflets <NUM> are placed onto tester <NUM>, tested according to the categorization technique, and sorted according to their categories - e.g., into collections, and (ii) subsequently, leaflets from a single category are re-placed onto tester <NUM> and retested according to the grouping technique. It is hypothesized by the inventors that the grouping of leaflets <NUM> assigned to the same leaflet flexibility category, according to their flexibility values, may enable grouping of leaflets into groups of highly similar flexibility. <FIG> are schematic illustrations of unsuitable leaflets, in accordance with some applications of the invention. <FIG> schematically illustrates a leaflet 30d that is insufficiently flexible for use in a prosthetic heart valve. In response to the derived flexibility value, circuitry <NUM> typically assigns the leaflet to an appropriate category (e.g., an "unsuitable" or "discard" category). This is represented in <FIG> as category "x. " For example, <FIG> shows category "x" spanning a range D162 of flexibility values, range D162 being separated from range D144 of flexibility values of category "<NUM>" by threshold D106. Leaflet-flexibility values within range D162 may characterize leaflets unsuitable for use in a prosthetic heart valve. Although <FIG> depict unsuitable category "x" leaflets that are unsuitable for being overly inflexible, this depiction is not meant to exclude the possibility that excessively flexible leaflets may be assigned to an alternate category "y" of excessively flexible leaflets. For example, <FIG> shows category "y" spanning a range D164 of flexibility values, range D <NUM> being separated from range D <NUM> of flexibility values of category "<NUM>" by threshold D124. Leaflet-flexibility values within range D164 may characterize leaflets unsuitable for use in a prosthetic heart valve. Typically, unsuitable leaflets assigned to either category "x" or "y" <NUM> are discarded.

It is to be noted that, although leaflets <NUM> in <FIG> and <FIG> drape symmetrically, the teaching includes deriving leaflet-flexibility values and/or assigning categories for a leaflet that drapes asymmetrically, at least up to a certain degree of asymmetry. <FIG> shows a non-isotropically-flexible leaflet 30e that drapes asymmetrically as a result of its non-isotropic flexibility. Circuitry <NUM> may be configured to categorize non-isotropically-flexible leaflets as described hereinabove, at least up to a threshold degree of asymmetric draping. For some applications, for a leaflet whose draping asymmetry is greater than a threshold degree of asymmetry, circuitry <NUM> may assign the leaflet to an appropriate category (e.g., an "unsuitable" or "discard" category), such as category "x" described hereinabove.

For some applications, circuitry <NUM> identifies non-isotropic flexibility of a leaflet <NUM> by calculating a difference between axial distance D92 and axial distance D94. Alternatively or additionally, circuitry <NUM> may identify non-isotropic flexibility of a leaflet <NUM> by calculating a difference between axial distance D88 axial distance D90. It is hypothesized by the inventors that a difference between D92 and D94, and/or a difference between D88 and D90, will be greater for non-isotropically-flexible leaflets than for isotropically-flexible leaflets, thereby facilitating identification of non-isotropically-flexible leaflets.

As described hereinabove, circuitry <NUM> may be configured to detect asymmetric draping. In that case, the asymmetric draping is asymmetric draping that is caused by, and is indicative of, non-isotropic flexibility of the leaflet. Circuitry <NUM> may also be configured to detect asymmetric draping that is caused by, and is indicative of, improper positioning of the leaflet being tested, e.g., caused by the user improperly positioning the leaflet, and/or by slippage of the leaflet during elevation of the bar. In response to detection of such improper positioning, circuitry <NUM> typically assigns the leaflet to a "retest" category.

An exemplary reason for a leaflet to be assigned to the "retest" category is measurement error. In this context, the term "measurement error" is used to refer to situations in which image parameters and/or leaflet-flexibility values may not enable circuitry <NUM> to accurately assign leaflet <NUM> to a leaflet flexibility category. In such cases, indicator <NUM> may indicate a need to repeat the measurement and/or to adjust leaflet flexibility measurement conditions. For example, <FIG> show two types of measurement error, in which leaflets <NUM> may be assigned to the "retest" category that indicates a need to retest the leaflets. This is represented by a "<NUM>" in <FIG>.

<FIG> shows measurement error introduced by sub-optimal positioning of leaflet <NUM> on bar <NUM>. Another potential source of measurement error may be adherence of leaflet <NUM> to guide <NUM>, shown in <FIG>, which may cause slippage of the leaflet over the bar during elevation of the bar. <FIG> shows an adhesion site <NUM> at which leaflet <NUM> had adhered to platform <NUM> (e.g., guide <NUM> thereof), such that when bar <NUM> was elevated, the leaflet was pulled off of the bar to one side. Measurement error may be identified in response to a difference between (i) a direct distance D84 between first-leaflet-tip position D96 and bar-tip <NUM>, and (ii) a direct distance D86 between second-leaflet-tip position D98 and the bar-tip. It is hypothesized by the inventors that the difference between direct distances D84 and D86 may be greater when leaflet <NUM> is improperly positioned and/or has slipped. It is further hypothesized by the inventors that the difference between direct distances D84 and D86 is more strongly correlated with measurement error than with non-isotropic flexibility of a leaflet, facilitating discrimination between measurement error and proper measurement of leaflet flexibility.

For some applications, measurement error is identified in response to a difference between vertical axial distance d88 and vertical axial distance d90. For some applications, measurement error is identified in response to a difference between horizontal axial distance d92 and horizontal axial distance d94.

For some applications, circuitry <NUM> may detect instances of measurement error in response to a plurality of image parameters to, e.g., by cross-validation of image parameters. For example, circuitry <NUM> may compare a difference between D88 and D90, to a difference between D92 and D94. Alternatively or additionally, circuitry <NUM> may compare a difference between D88 and D92, to a difference between D90 and D94. In addition to one or both of these comparisons, circuitry <NUM> may also take into account direct distances D84 and D86. It is hypothesized by the inventors that the derivation of leaflet-flexibility values in response to more than one image parameter advantageously facilitates identifying measurement errors, e.g., distinguishing between (i) asymmetric draping caused by measurement error, and (ii) asymmetric draping caused by non-isotropic flexibility.

The use of a plurality of image parameters to derive leaflet-flexibility values is therefore hypothesized by the inventors to increase the validity and clinical utility of the flexibility categories to which leaflets <NUM> are assigned.

Claim 1:
Apparatus (<NUM>) for testing a plurality of prosthetic heart valve leaflets, the apparatus comprising:
a vertical mount (<NUM>); characterized by
a plurality of horizontal bars (<NUM>) movably coupled to the mount, each bar extending away from the mount along a respective bar-axis (D26) that lies on a respective vertical bar-plane (D28), and each bar configured to support a respective leaflet (<NUM>) along the respective bar-axis such that the respective leaflet drapes over the respective bar; and
an image sensor (<NUM>), positioned opposite the mount, facing the plurality of bars and the mount so as to be oriented to acquire an image that includes the plurality of leaflets draped over the plurality of bars.