Structural Heart: anatomy, repair & mechanics

Try a repair

Open Structural Heart from the main navigation and unlock the prototype. The initial synthetic Barlow case preserves an untouched baseline with bileaflet prolapse. Choose the P2 flail example to study focal chord rupture, or the reference case for comparison. Primary anatomy dimensions stay visible; supporting tissue/chord fields and Inspect structure expand when needed. Select a leaflet region and papillary anchor in the viewport or their numeric selectors. Preview a neochord and Apply edit; the worker automatically reassesses the case. Recalculate is also available. Shorten or lengthen it and compare again.

Use Duplicate for an independent alternative. Add a generic annuloplasty ring, or create a P2 resection followed by boundary approximation. Choose a loading experiment and recalculate every plan under the same pressures. Synchronized cameras and phase controls keep comparisons aligned. On mobile, Compare shows one canvas at a time with Original and Current plan buttons. Open editor controls jumps to anatomy, repair and loading; Return to valve brings the canvas back into view.

Save retains one complete case in this browser; Export creates a portable JSON file. New case replaces the open unsaved workspace. Import and browser reload discard cached result validity and require deterministic recalculation. The Repair table uses readable operation names, expandable settings and Edit/Remove actions; the sidebar links to that same history rather than duplicating it. Undo/Redo beside the viewport restores applied plan edits; an active trim draft instead uses stroke Undo/Redo. History replay is checked before a change is accepted, so removing or revising an earlier operation cannot silently leave invalid dependent attachments.

Starting case: Barlow disease

The Barlow example represents diffuse redundant, thickened mitral tissue, an enlarged annulus and elongated intact chords with prolapse of both leaflets. Barlow disease does not require chord rupture. The separate P2 flail example disables P2 native chord support; it is not the default Barlow mechanism.

Preset inputs are annular diameter 42 mm, leaflet-length parameter 22 mm, synthetic thickness 2 mm, excess tissue 30% and native chord rest-length increment 10 mm. Flail is Off. Other valves and prescribed loading retain reference values. These are illustrative settings chosen for this reduced model, not measured patient anatomy, diagnostic thresholds or a prescription for repair. The length parameter still passes through the existing excess-tissue and anterior-leaflet geometry factors.

Pressure and intact elongated chords permit representative systolic bileaflet displacement toward the atrium. An original mitral display term adds redundant mid-leaflet billowing: (excess/100) × effective length × 0.55 × sin²(πu) × sin²(πv) × clamp((θ−0.9)/0.6, 0, 1). It vanishes at attachments, free edges and shared scallop seams, so solved free-edge and chord constraints are preserved. This is regional-hinge geometry with an illustrative surface shape, not finite-element reconstruction of local myxomatous tissue bending. Annular disjunction, tissue histology, dynamic annular curling and arrhythmic risk are not inferred. The displayed opening and gap remain geometric surrogates. The separate suspected categories below use original guarded rules; they do not establish clinical severity.

Geometry and identities

The model uses indexed XYZ surfaces in a common left-posterior-superior (LPS) frame, with mm length, N force and mmHg pressure. Original parameterized surfaces represent annuli, six mitral scallop regions, three tricuspid regions, semilunar cusps, two simplified papillary groups per AV valve, chords, roots, sinuses, sinotubular junctions and ventricular context. This is deliberately simplified regional anatomy, not a complete atlas.

Mitral regions within the same leaflet share boundary coordinates and vertex identities. Each region has a 10×10 surface grid. Annular diameter, shape, height, saddle, leaflet length/excess, papillary depth/spacing, chord elongation, material coefficients and aortic orientation alter geometry or constraints. Papillary displacement preserves native chord rest lengths; explicit elongation changes them.

The semilunar cusp height uses L × (offset + cos θ) × u along its local positive z axis, plus annular and curvature terms, before valve orientation is applied. L is effective leaflet length and u runs from attachment to free edge. Offset is 0.22 for aortic and 0.18 for pulmonic cusps; the pulmonary reference length is 14 mm and hinge stiffness is 1, compared with the generic reference stiffness of 5. The lower pulmonary stiffness permits closure under the smaller prescribed pulmonary pressure difference. These are original geometry/compliance choices, not measured cusp proportions, clinical calibration or material laws. AV leaflets retain their separate ventricular-side construction.

P2 flail removes its native chord constraints. Restriction changes hinge stiffness and resting angle (tethering); commissural restriction changes stiffness, resting angle and motion bounds rather than welding a pathological commissure. Perforation and resection remove retained mesh cells. Vegetation adds a structural mass to the view only: infection, embolic risk and lesion inertia are not modeled.

Mitral orientation

A1 faces P1 at the anterolateral end, A2 faces P2 centrally, and A3 faces P3 at the posteromedial end. Both leaflets are numbered in the same lateral-to-medial direction. The anterior leaflet faces the aortic root; papillary support, selection labels and repair attachments use the same geometry. The annular saddle is highest anteriorly and posteriorly. The mesh remains an idealized educational shape, not a patient reconstruction.

What each edit changes

A ring blends the annular diameter and aspect ratio toward device dimensions by 1/(1+relative compliance), and changes annular attachment height while papillary anchors remain fixed. The ring is generic; no manufacturer device behavior is asserted.

Neochords add tension-only constraints at explicit leaflet coordinates and papillary anchors. Existing chords may be detached, relocated or assigned a new rest length. Removed native attachments remain identifiable but disabled. A neochord attached to removed or perforated tissue is rejected.

P2 triangular removal is quantized to retained 10×10 mesh cells and changes pressure-loaded area and effective hinge stiffness. Boundary approximation contracts the retained cut margins geometrically, with zero displacement at adjacent scallop seams. This is a geometric closure constraint, not a sutural-force or watertight reconstructed-tissue solver. One active resection is supported; revise it rather than stacking cuts.

Thinning retains the mesh and reduces effective thickness; bending stiffness scales with remaining thickness cubed. A patch restores removed mesh cells in the chosen region with a separate displayed surface and chosen synthetic thickness/relative stiffness. It shares boundary vertices with retained tissue; area-weighted thickness-cubed stiffness enters the regional hinge model. Its geometry follows the reference surface, not an inferred patient patch shape. Patch interfaces, suture stresses, tissue failure and healing are not solved. Anatomy edits establish the plan geometry before explicit repair constraints are replayed; later operations are revalidated when an earlier edit changes.

Clips, sutures and pledgets

A mitral clip bridges anterior and posterior regions; a tricuspid clip bridges distinct leaflets. Sutures connect two retained mesh vertices, including opposite sides of a regional cut. The selected anchors use the 0.1 mesh grid. Missing tissue, wrong-valve devices/attachments and reserved identity collisions are rejected. One clip or suture per valve is supported; revise it instead of stacking unmodeled contacts.

A generic clip or suture retains the original single-pair tension-only energy ½k·max(0, separation−target gap)². Tension is k·max(0, separation−target gap), in N. Named G4 profiles instead distribute that same total synthetic stiffness over nine paired material samples, each using k/9 and the same target gap. Three samples span the arm width and three span its full length from the chosen distal grasp toward the attachment. Local annular-ellipse arc length converts width to surface coordinates; opposing tangents align the two footprints. These coordinate choices and finite springs are original approximations, not manufacturer mechanics.

All mesh cells covered by a named footprint must retain tissue. A footprint extending outside one selected region or across missing tissue is rejected. This is a coarse geometry check, not proof of leaflet insertion, capture, adequate tissue or device eligibility. Regional rotations respond to pressure and the sampled constraints; local tissue folding/contact is not solved or forcibly closed. Residual gaps may remain large, and a larger profile is not assumed better. Same-region sutures have limited effect because both bites share one hinge.

Gap reports the largest paired-sample separation. Tension reports the largest individual spring force, not total implant load or tissue stress. Named devices are drawn as two ribbons using the published arm dimensions plus an original 3 mm center marker. They are not engineering CAD or a delivery/deployment simulation. Capture success, safety, durability, device sizing and clinically predictive regurgitation are not modeled; the separate flow summary remains an assumed-flow geometric estimate.

Pledgets add two pads with explicit width and thickness at suture bites. They show a finite support footprint; this model does not predict contact stress or increase suture holding strength. Published pledget contact work in myocardium does not validate these leaflet mechanics.

MitraClip and TriClip G4 profiles

Choose the mitral or tricuspid valve, then a G4 size profile or the generic bridge. Expand grasp positions and constraint settings for precise placement or synthetic gap/stiffness changes. These are schematic representations using published Abbott arm dimensions. The choices do not establish suitability, successful capture, residual regurgitation or a recommended device. The simulator does not reproduce a delivery system or the complete implant.

Arm length is the published maximum arm/coaptation length; width is the arm width. Neither is a measured tissue-grasp depth, achievable coaptation area or a patient-specific safety limit. G4 profiles are identified explicitly; no claim about the latest device generation is made.

Drawing, trimming and view controls

Drag to rotate; wheel or pinch to zoom. View also provides numeric zoom, yaw, tilt and roll. Comparison cameras stay synchronized. Play uses elapsed-time animation and interpolates adjacent solved hinge angles, including the cycle boundary, to display smooth motion at the prescribed heart rate. Both views use the same display phase. This adds display positions, not new mechanical solutions. Numeric pressures and metrics, the phase slider and the paused state use the nearest solved frame (24 per cycle by default). Playback suspends its clock when the page is hidden and is unavailable while unsolved. Geometry-editing tools pause playback.

Draw creates surface-anchored markings; Measure displays endpoint distance in mm. Markings follow the same surface points through the cycle and are saved with the synthetic case. Undo marking removes the latest drawing. They are annotations, not tissue edits.

Trim brush builds a visible draft on one leaflet region. Paint adds cells to the proposed cut; Erase removes cells from that draft. Stroke Undo/Redo corrects the selection, Apply commits it and Cancel discards it. Reopen an applied brush operation from the Repair table to revise its cells. Fine and Wide set the brush footprint. Annular attachments and regional seams are protected; invalid cuts or cuts through retained repair attachments are rejected. Cuts remain discrete 10×10 regional mesh edits, not arbitrary smooth surgical cuts or greater anatomical precision.

Edge trim previews bounded free-edge removal. Place suture drags between two retained mesh vertices. Tension neochord drags an existing neochord vertically to preview its rest length; Apply reassesses the resulting force and geometry. The Repair tools panel opens beside the edited image, with the same procedure and numeric fields as the Repair tab. Numeric inputs remain available for precision and keyboard use.

Chamber context and axes

Atrial and ventricular envelopes can be shown or hidden independently. The mesh, structural axes and labels are controlled in View. Reference axes identify LV/RV long axes, the mitral short axes and aortic–mitral orientation in the shared LPS frame. These are synthetic landmarks, not registered patient axes.

Enter width, depth, long-axis height and volume for each chamber. With Fit volume enabled, dimensions are uniformly scaled by the cube root of target volume divided by ellipsoid volume; aspect ratios are preserved. With it disabled, entered dimensions are used and volume is π/6 × width × depth × height, converted from mm³ to mL. Chamber envelopes remain reference context, not solved dynamic chamber volumes, material meshes or exact anatomical reconstructions. These manual context-envelope entries do not themselves modify valve loading or papillary geometry. The separate Echo & ventricular function inputs use the explicitly documented sensitivity mappings below.

Whole-heart display and supporting structures

The outer heart, septal context, LVOT/RVOT and left/right atrial appendages are original schematic surfaces positioned from the current synthetic annuli and chamber envelopes. They are not patient anatomy or registered to a scan. Display controls can hide context structures while preserving the valve workspace, including independent LVOT and RVOT visibility. The outflow tracts connect schematic ventricular regions to their own valve locations; they are not measured luminal casts or computational flow domains.

Fibrous context identifies the aorto-mitral continuity, left/right trigones and central septal attachment. Annular guides do not imply complete solid fibrous rings: mitral fibrous tissue may be discontinuous and most of the tricuspid annular support is fibroadipose rather than a continuous fibrous ring. Pulmonary support is muscular and remains separate from the trigone/curtain system.

The outer envelope is a closed radial support surface around current chamber points with a 2 mm display margin. LAA is drawn as a narrow-neck lobulated finger and RAA as a broader triangular shape, using the current atrial dimensions. These offsets, shape factors and margins are original display choices. Appendage outlines and the closed outer envelope show approximate relationships only. They do not reproduce individual lobes, wall thickness, coronary anatomy, electrical conduction, trabeculation or a full imaging segmentation. Their mesh dimensions, curves and offsets are original display heuristics; they add no tissue coupling, mechanics or patient-specific operative prediction.

Choose a regurgitation mechanism

Mitral Carpentier type I describes normal leaflet motion with a coaptation defect, such as annular enlargement or perforation. Type II is excessive motion, including prolapse or flail. Type IIIa restricts leaflet motion during opening and closure; type IIIb restricts systolic closure through ventricular/papillary tethering. These describe mechanisms, not severity or a specific repair outcome.

The aortic repair-oriented classification uses type I for normal cusp motion with annular/root enlargement or a tissue defect, type II for cusp prolapse and type III for restricted cusp motion. Aortic type III is not a mitral type IIIb category. Multiple mechanisms may coexist clinically.

Preview mechanism creates a reversible anatomy operation. Applying it resets flail, restriction, fusion, excess, elongation, perforation and vegetation before the selected example is assigned; dimensions not specified by that example remain unchanged. Existing repair history is revalidated. These examples do not classify images, assign severity or establish which procedure will work.

Mitral I sets diameter to at least 42 mm, length 20 mm and thickness 1 mm. II sets diameter to at least 38 mm, length 22 mm, thickness 1.5 mm, excess 25% and elongation 8 mm with intact chords. IIIa uses length 19 mm, thickness 1.8 mm, stiffness 8, restriction 40 and fusion 35. IIIb uses diameter at least 38 mm, length 20 mm, thickness 1 mm, papillary depth 43 mm and spread 24 mm. Other mitral examples use depth 32 mm and spread 17 mm; stiffness is 5 except IIIa. These are original tuning values, not phenotype diagnostic criteria.

Aortic I uses diameter at least 32 mm, length 14 mm, thickness 1 mm and stiffness 5. II uses length 16 mm, thickness 1 mm, stiffness 4 and excess 15%; the noncoronary regional hinge can reach 1.95 radians before the fusion adjustment, while other semilunar hinges stop at π/2. III uses length 13 mm, thickness 1.8 mm, stiffness 8, restriction 40 and fusion 25. The reduced aortic I example changes annular geometry; it does not reproduce every root-dilatation or perforation subtype.

Additional synthetic energy terms distinguish motion phases: mitral IIIa and aortic III target hinge angles 1.04 and 0.95 radians with stiffness weight 8 in both phases. AV systolic tethering adds ½ × stiffness × 10 × tethering severity × retained-area fraction × max(0,θ−1)² only when ventricular pressure exceeds atrial pressure. This unilateral penalty resists motion beyond 1 radian; it never pulls a leaflet already below that angle toward better closure. IIIb adds severity 0.5, bounded to 1. These original potentials are not measured tissue laws or clinical restrictions in degrees.

Enter echo measurements

Optional entries include left/right atrial volume, LV end-diastolic/end-systolic volume, LVEF, LV diastolic/systolic diameter, septal/posterior wall thickness, left atrial dimension, LVOT/aortic root diameter, RV basal/RVOT diameter and RV end-diastolic/end-systolic area. Volumes use mL, linear dimensions mm and RV areas cm². These are user-entered measurements, not values extracted automatically from a scan.

For paired LV volumes, EF = 100 × (EDV−ESV)/EDV; paired volumes take priority over a separately entered LVEF, and a difference above 5 percentage points is flagged. For paired RV areas, FAC = 100 × (EDA−ESA)/EDA. FAC remains separate from the selected qualitative RV function. End-systolic values cannot exceed their paired end-diastolic values; absent entries remain unspecified.

These inputs can scale schematic chamber envelopes. LVOT diameter controls the displayed outflow/clearance cylinder; aortic root diameter scales the sinus envelope independently of the annulus, and RVOT diameter scales the pulmonary outflow. Septal and posterior wall thickness add an illustrative LV wall outline; when only one is entered it is mirrored to the other side. These are geometric display mappings, not a reconstruction of actual wall distribution. A squared-sine display contraction interpolates entered diastolic/systolic dimensions or volumes; atrial volumes remain reference values. The display helper bounds schematic dimensions to 1–180 mm and drawable chamber volume to at least 1 mL while retaining the original entered measurements. These are numerical/display safeguards, not physiologic reference ranges. Ellipsoid scaling and smooth display interpolation do not reconstruct patient anatomy, prove ventricular function or infer tissue material properties. The entered dimensions, function and wall-motion settings are not a validated patient-specific repair model.

LV segment map and ventricular function

The polar map follows the AHA 17-segment names: anterior at the top, septum to the left, inferior at the bottom and lateral wall to the right. The outer and middle rings contain six basal and six mid-ventricular segments; the inner ring has four apical segments, with the apical cap at the center.

Click a segment to set normal, hypokinetic, akinetic or dyskinetic motion, shown in green, yellow, red or blue. Scores are 1, 2, 3 and 4. The wall-motion score index averages segments 1–16; segment 17 is retained as a location marker/annotation but excluded from this index because routine echocardiographic wall-motion assessment does not score the apical cap. The colors are display choices, not scar maps or predicted coronary territories.

An entered LVEF, RV function category and regional motion do not establish contractility or myocardial viability. Any reduced-model changes to load or papillary geometry are illustrative sensitivity experiments, not measured stress, strain or individualized ventricular mechanics.

How echo inputs affect the reduced model

EF, FAC and wall motion do not determine ventricular pressure. All LV, RV, aortic, pulmonary and atrial pressures honor the entered Loading values. Function inputs affect the separate flow-budget and tethering assumptions. The LV contextual function factor is clamp(0.45 + 0.55 × EF/60, 0.45, 1.1), or 1 − 0.35 × mean regional loss when EF is absent. Regional loss values are 0, 0.35, 0.7 and 1 for normal, hypokinetic, akinetic and dyskinetic motion, averaging segments 1–16. Only the regional-motion fallback without EF/paired volumes uses 5 × this factor as its assumed ejection budget; EF and paired-volume budgets use the volume relationships below. The factor never scales pressure or establishes myocardial contractility.

Qualitative RV function supplies contextual factors 1, 0.85, 0.65 and 0.45 for normal, mild, moderate and severe dysfunction. When no category is entered, FAC gives clamp(0.45 + 0.55 × FAC/35, 0.45, 1.1). This factor informs RV tethering and an optional 5 × factor fallback budget, not RV pressure or an area-derived stroke volume. If the entered loading itself provides no pressure-open portion, the assessment is unavailable rather than inventing flow.

Mitral papillary displacement combines local motion loss, LV enlargement and EF loss. Dilation is clamp((LVEDD−50)/35, 0, 1), or clamp((LVEDV−120)/200, 0, 1) if LVEDD is absent. EF loss is clamp((60−EF)/60, 0, 1). Severity = clamp(0.6 × local loss + 0.25 × dilation + 0.15 × EF loss, 0, 1). The anterolateral teaching group uses AHA segments 1, 6, 7 and 12; the posteromedial group uses 4, 5, 10 and 11. This coarse map is not an individual coronary distribution or imaging-derived papillary position.

At severity s, anterolateral and posteromedial anchors receive local offsets (+4s,+3s,−10s) and (−4s,+3s,−10s) mm. A1/P1 use lateral severity, A3/P3 medial severity and A2/P2 their average; posterior tethering is multiplied by 1.1 and bounded to 1. Offsets move rendered papillary groups and actual chord endpoints together while native chord rest lengths are preserved. Dysfunction does not automatically rupture chords or create flail.

RV tethering severity is clamp(0.75 × max(0,1−RV factor) + 0.25 × clamp((RV basal diameter−42)/40, 0, 1), 0, 1). Two tricuspid anchor groups move (0,−3s,−8s) and (0,+3s,−8s) mm, with the same regional tethering severity. All coefficients, thresholds and mappings in this section are original bounded sensitivity assumptions, not measured patient myocardial mechanics.

Local DICOM images

Open DICOM reference and select a source series. A browser worker parses CT, MR and standard ultrasound Part 10 files with uncompressed explicit or implicit VR little-endian 8/16-bit monochrome pixels. Shared/per-frame spatial and temporal metadata are read when present. Rescale slope/intercept is applied to pixel values; MONOCHROME1 changes the display, not segmentation intensities. Frames are never assigned invented spatial positions.

The reference view supports slice navigation, grayscale windowing and two-point measurements. In-plane distance uses row/column Pixel Spacing. A measurement can populate a synthetic anatomy draft for annular diameter, leaflet length or papillary depth, then requires Preview and Apply. It remains a manually interpreted dimension: oblique or foreshortened planes can misrepresent the intended measurement. Missing calibration disables applying it.

Image-derived reconstruction requires at least three calibrated, parallel slices from one physical stack and one identified phase, or an internally consistent stack with phase unknown. A known frame of reference, consistent pixel spacing, dimensions and orientation, and increasing physical slice positions are required. Duplicate planes, gaps above 5 mm and shifted/tilted grids are rejected; resample them in a suitable imaging tool. A cine sequence is never treated as slice depth. Unknown phase is not proof of ECG gating.

Patient-based CT/MR stacks are supported. Standard ultrasound images may be viewed as references; an ordinary 2D cine does not provide a reconstructable 3D valve. Compressed data, colour cine, vendor-private 3D/4D echo, SEG and Surface Segmentation objects are not supported by this importer. SlicerHeart documents vendor-specific decoding/export needs; compatible source pixels and physical geometry must be available before this workflow can use them.

Import is bounded to 256 files, 128 MB total, 64 MB per file and 16 million voxels. Parsing is cancellable. Source pixels and identifiers are not uploaded, broadcast to classrooms, saved in browser storage or included in the synthetic case export. Close & clear images releases the reference workspace. Use appropriately de-identified files; local processing is not a de-identification service.

Seed, review and correct tissue

Automatic draft starts On. Select a source slice and click the intended valve tissue. The selected point defines a local crop and intensity seed. This is bounded intensity region growth, not anatomical recognition, a trained classifier or validated valve segmentation. Similar-intensity blood, myocardium, calcium or artifact can be included; thin leaflet tissue may be missed. Review the marked tissue on every slice.

The draft includes six-face-connected voxels within the chosen intensity tolerance of the seed value. Tolerance is in the rescaled image units, not a universal tissue threshold. Changing grayscale contrast affects visibility only. The source pixels remain unchanged. Replace with draft repeats growth and replaces the manual mask; it does not preserve corrections.

With Automatic draft Off, select a region and paint or erase tissue on its slices, then Build surface from mask. The visible brush footprint uses source pixels, not mm; it is clipped to the selected region. Continuous strokes sample the path between pointer events. Undo mask and Redo mask keep up to 20 completed edits. A new region starts a fresh mask history; a new edit clears redo. Escape, lost pointer capture, changing slice or leaving the focused canvas cancels an unfinished stroke. Manual edits can still create disconnected regions or holes, which need review. Mask edits do not update the 3D surface until rebuilt.

The region radius is 3–25 mm, bounded to at most 97×97 pixels and 64 planes. The crop keeps the actual image spacing, orientation and plane positions. These are performance limits, not minimum image-resolution requirements for clinical accuracy. Worker reconstruction can be cancelled and has a time limit; smaller crops or simpler masks may be needed.

Image-derived surface and editing

The image model extracts the 0.5 boundary of a binary tissue mask with six tetrahedra per grid cell and shared edge vertices. Coordinates use the DICOM patient-space transform: image position plus column index × column spacing × row direction, plus row index × row spacing × column direction. Actual slice positions supply depth. Lengths remain in mm and coordinates in LPS; the source is not replaced by a synthetic valve template.

The reconstructed boundary is a closed shell around selected tissue, not automatically a leaflet midsurface or a mechanical volume mesh. Exterior zeros close the mask at the crop border. If selected tissue reaches that border, a warning identifies the artificial closure: expand the crop or correct the mask. The midpoint surface and apparent thickness depend on voxel resolution and segmentation; they are not measured tissue boundaries. A maximum of 80,000 triangles bounds the prototype.

Rotate, wheel/pinch zoom, Drag tissue and Trim surface edit a separate geometry copy. A visible footprint shows the local brush; surface radius uses mm and Shape strength adjusts displacement. Trim follows face-connected tissue rather than removing a nearby disconnected sheet. Drag tissue spreads a smooth displacement over connected mesh edges, with a bounded step and local triangle-orientation checks. These are editing safeguards, not physical elasticity, self-intersection proof or a biomechanical repair calculation. Trimming can still open the shell, and edited geometry can be implausible.

Export surface saves local JSON containing the mask, physical grid, modality/phase and original/edited surfaces. Export is blocked during reconstruction and whenever the mask differs from the built surface; rebuild first. Undoing back to the exact built mask restores consistency. STL review also excludes unfinished geometry strokes and stale surface sources. It does not export source pixels or patient identifiers, and it is separate from the synthetic case format. Source-derived geometry can still be sensitive. No valve labels, chords, unloaded shape, material properties, motion, repair success, regurgitation or hemodynamic response are inferred from this surface. The synthetic pressure/hinge solver does not run on it.

Image-editor controls and limits

Original outline shows the unchanged reconstructed surface. Surface Undo/Redo keeps up to 20 completed edits; Reset surface returns to the reconstructed original and can itself be undone. These temporary surface and mask histories are separate and are not exported. Escape or a cancelled pointer stroke restores its starting geometry. Rebuilding from the mask creates a new original and replaces surface edits. Source pixels and the segmentation are not changed by surface editing.

With the surface canvas focused, V rotates, G selects Drag tissue, T selects Trim surface, and [ / ] changes radius. Ctrl/Command Z undoes; Ctrl/Command Shift Z or Ctrl/Command Y redoes. With the source-slice canvas focused, B paints, E erases and [ / ] changes the pixel brush radius; the same undo, redo and cancellation shortcuts apply. Shortcuts ignore text fields and editable text.

The shared editing.ts helper uses frontmost triangle picking, bounded stroke sampling, connected face/edge neighborhoods and finite geometry checks. Shape displacement has a smooth radial falloff and is limited to the smaller of 5 mm or half the brush radius before strength is applied. A local triangle-orientation check repeatedly halves a rejected displacement. The step limit and preservation checks are original numerical safeguards; they do not preserve tissue volume, prove mesh quality or establish clinical anatomy.

Export image geometry to CAD or a slicer

After reviewing the tissue mask and editing its reconstructed surface, open 3D Print / CAD. Download STL (mm) exports the current edited triangles; Download print manifest records mm, LPS coordinates, 1:1 scale, dimensions and mesh checks. The original reconstruction remains unchanged. STL has no standardized units field, so choose millimetres at import. This is a triangle surface, not a parametric CAD or STEP model.

Export is disabled while reconstructing or editing, after unreconstructed mask changes, or when selected tissue reaches the crop boundary. Expand or correct the mask and rebuild instead of treating its artificial crop closure as anatomy. Empty, invalid, open, nonmanifold, degenerate, duplicate or inconsistently wound geometry also blocks STL export. Checks include coordinate precision and zero enclosed volume.

Separate closed parts and inward-wound parts are reported for review; the exporter does not silently weld or repair them. These checks do not detect all self-intersections, inadequate wall thickness, nesting errors or manufacturing problems. Inspect segmentation against source images and the final mesh in CAD or a slicer. Export carries geometry only, not patient mechanics, clinical suitability or a validated implant design.

Reduced mechanics and contact

The regional-hinge-v1 backend minimizes a common quasi-static energy with one rotation per leaflet region. Components are hinge bending ½k(θ−θ₀)², symmetric neighboring-angle coupling, approximate pressure work ΔP·A·L·0.42·cos(θ) and tension-only chord energy ½kc·max(0,l−l₀)². Pressure work samples continuous regional angles. 1 mmHg = 0.000133322 N/mm². Dimensions, hinge coefficients, coupling and the 0.42 lever factor are original illustrative choices, not fitted clinical measurements.

Same-leaflet boundary interpolation couples adjacent regions, and all affected chord energies enter each coordinate minimization. Trimming and resection scale pressure area by the removed mesh-cell fraction and hinge stiffness by 1−0.25×that fraction. These are reduced-order assumptions rather than shell constitutive laws.

Contact is a unilateral central exclusion envelope: leaflet radial reach is limited to 0.15 mm from the valve axis. It prevents crossing the central axis but does not provide general leaflet-to-leaflet collision, contact stress or an excessive-penetration guarantee. General penetration is marked unavailable, never reported as zero. Free-edge proximity is measured separately in 3D.

Deterministic bounded coordinate minimization uses 28 golden-section steps per coordinate and repeats until the greatest angular update is below tolerance (default 0.0005 rad, maximum 80 sweeps). Convergence is a numerical stopping condition, not evidence of anatomical accuracy or a global minimum. Failed calculations provide no current frames. Previous results remain stored as stale; the viewport uses edited reference geometry until recalculated.

Prescribed pressure and coupling boundaries

LA and RA means are prescribed constant loads. LV and RV pressures use a squared-sine systolic pulse lasting 42% of the cycle, between the entered diastolic and systolic values. Echo EF, FAC and wall-motion inputs do not rescale these pressures. Arterial pulses lag by 4.5% of a cycle, allowing the early systolic opening gradient. The default solve uses 24 phases. Heart rate sets displayed cycle duration; this quasi-static solver has no inertial rate dependence.

Each comparison and alternative uses the same loading inputs. Baseline, higher afterload, higher filling pressures, low pressure and pulmonary-pressure challenges are available; custom values allow repeated load sweeps. Inputs are prescribed, not the result of solved circulation. A separate educational assessment uses solved geometry and an explicit ejection budget to estimate relative flow burden. It does not replace the prescribed pressures or infer effective orifice area, tissue stress or strain.

The aortic and mitral structures share coordinates. Aortic orientation and root dimensions affect the synthetic LVOT clearance measurement; there is no myocardial deformation coupling or complete aorto-mitral continuity tissue model. Annular and papillary positions are fixed within each pressure experiment; anatomy edits and the documented echo-derived offsets change them between experiments. Time-varying boundary motion and a dynamically coupled circulation are future extensions. The shared-flow assessment below conserves an assumed serial flow budget without solving chamber pressure or volume feedback. No wedge-to-LA adapter is currently used.

Flow and acceleration: what is estimated

The colour-flow overlay is an original moving illustration attached to the displayed valve geometry. Forward flow follows filling for mitral/tricuspid valves and ejection for aortic/pulmonic valves; residual reverse flow uses the opposite phase. Read its colour convention and limits below. Numerical flow estimates come from the separate geometry/budget calculation, not the displayed jet pixels.

The assessment uses the complete solved cycle, with 24 phases by default. A pristine synthetic reference is solved with the same entered loading and solver settings but without echo-derived tethering; it is distinct from the untouched pathological baseline used to compare repairs. At each valve, positive prescribed upstream-minus-downstream pressure defines the opening phase. An ideal-orifice capacity sample is 6 × projected opening in cm² × √(positive pressure difference/4), in L/min. This is a dimensional Bernoulli/continuity illustration, averaged across the complete cycle; no vena-contracta contraction coefficient or pressure recovery is solved.

Closing-phase leakage uses a geometric excess relative to the pristine same-phase reference without echo-derived tethering. Subtract reference uncovered fraction × current annular area and a 2% current annular-area allowance from the projected opening. Compare this with excess free-edge gap above the larger of reference gap or contact tolerance, multiplied by the representative closure span and divided by 100 to give cm². The larger nonnegative excess is capped at annular area. The span is the mitral diameter, or three mean annular radii for a three-region valve. These are original regularizers for coarse geometry; the result is not EROA, vena contracta or a clinical regurgitant orifice. Closed-phase summary values are weighted by √(closing pressure difference/4).

Each valve receives a reverse-to-forward capacity ratio k. The forward denominator has a 0.01 L/min floor; k is bounded from 0 to 9 and saturation is flagged. These numerical bounds prevent unstable estimates; they are not physiologic limits. The model uses the ratio to apportion the assumed flow budget, rather than treating its raw geometric capacity as a measured output ceiling.

The displayed velocity ratio compares Q/A with the pristine synthetic reference: (current forward flow / gross budget) × (reference open fraction × reference mean open area) / (current open fraction × current mean open area). The relative gradient index is its square, following the proportional relationship in simplified Bernoulli. These dimensionless ratios do not report Doppler velocity, a mean gradient in mmHg or a catheter pressure difference. Geometric and effective opening differ; mean clinical gradient averages instantaneous squared velocities. A zero budget makes both ratios unavailable, and an unresolved opening makes the assessment unavailable.

Read the colour-flow illustration

The camera acts as a virtual probe: the dominant red hue indicates motion toward it and blue away. Rotating the view can therefore change the colour of the same anatomical flow. This adopts the common Doppler colour convention, not an oxygenation, disease or severity code. Real ultrasound colour maps can be configured differently.

Real Doppler jet appearance depends on gain, velocity scale, beam alignment, pressure/loading and receiving-chamber constraints. Wall-hugging or eccentric jets can appear deceptively small. Clinical regurgitation grading integrates multiple measurements and anatomy; a jet image alone is insufficient. Stenosis assessment also considers flow, valve morphology and quantitative measurements, because velocity and gradient change with flow.

Here, the colour field, moving texture and sparse contrasting mosaic accents are generated artwork. A bounded tube follows the geometric path, brightens around a schematic narrowing and fades when viewed across its axis. The texture is deterministic and repeats with cardiac phase. It is clipped by the selected view and opaque tissue. These choices do not result from an ultrasound beam, sampled blood velocities, measured Nyquist limit, actual aliasing, turbulence calculation or CFD/FSI. The drawing cannot supply a vena contracta, PISA, EROA, regurgitant volume or clinical grade. The separate suspected-grade categories use explicit synthetic rules, not pixel colour, brightness or jet area.

How the four valves interact

The assumed ejection budget B defaults to 5 L/min and may be zero. When supplied from LV end-diastolic and end-systolic volumes, B = (LVEDV − LVESV) × heart rate / 1000. This is a gross LV ejection rate, not forward cardiac output in the presence of regurgitation. Exact paired LV volumes are not reduced again by EF or RV multipliers. Otherwise EF uses entered/contextual EDV × EF/100 × heart rate/1000; regional motion without EF uses a 5 L/min reference multiplied by the LV contextual function factor; absent function data use the editable 5 L/min default. An available RV contextual budget of 5 × RV contextual function factor may cap only these assumed fallback budgets. This RV cap never overwrites the paired-LV-volume total and is not measured RV output. The final common budget bounds both ventricular turnovers in the flow illustration.

Using the four reverse-to-forward ratios, common net flow F = B / [1 + max(kmitral + kaortic, ktricuspid + kpulmonic)]. For each valve, gross forward flow is F × (1+k) and reverse flow is F × k, leaving the same net F at all four valves. Left ventricular turnover is F plus mitral and aortic recirculation; right ventricular turnover is F plus tricuspid and pulmonic recirculation. The opposite side is assumed to adjust to the serial-flow limit. No shunt, transient chamber storage or unequal sustained pulmonary/systemic net flow is introduced.

This bookkeeping illustrates why a regurgitant lesion can reduce forward perfusion, while mixed stenosis/regurgitation changes the gross flow passing through each valve. Repair of one valve may change the estimated velocity and gradient at another without changing its geometry. It is not direct tissue coupling, remodeling or a clinical prediction of multivalve repair. Prescribed pressures do not automatically normalize after an edit.

Read the repair comparison

The summary evaluates mitral, aortic, tricuspid and pulmonic valves against the untouched baseline under the same inputs. Read opening/narrowing, residual leak proxy, edge proximity and flow burden together. The overall statement describes a comparative geometric tradeoff, not surgical success, durability, a treatment recommendation or a probability of benefit.

A smaller residual gap can coexist with reduced forward opening. Reduced leakage can lower recirculating flow and thus lower a gradient even if an opening has narrowed; conversely a small opening can raise the velocity index. Clinical post-repair evaluation integrates regurgitation, valve gradients and multiple imaging/hemodynamic findings. The prototype table cannot substitute for that assessment.

The reduced-opening flag means mean projected area below 80% of the pristine reference. A residual-gap flag means the weighted leak proxy exceeds 0.5% of annular area. Free-edge separation is flagged above the selected contact tolerance. These are original geometric conventions, not clinical cutoffs. Changes above 5% of baseline opening, 0.5% of annular area for leakage or 0.1 mm of gap inform the comparative statement. Favorable geometry, Trade-off and Needs revision describe only these rules.

Coaptation here means sampled free-edge proximity, not measured leaflet contact area or sealing force. Prolapse alone is not assigned a regurgitation grade. Stale or failed mechanical results must be recalculated before this assessment is current; patient-derived image surfaces remain geometry-only and never enter these flow or repair estimates.

Suspected categories: original teaching rules

Each valve has separate suspected stenosis and regurgitation categories: None detected, Mild, Moderate, Severe or Indeterminate. These are unvalidated model categories shared across all four valves, not ASE severity thresholds, a clinical diagnosis or a recommendation. None detected does not establish a normal valve or exclude disease. Jet colour, area and brightness do not enter the rules.

Suspected stenosis first compares mean pressure-open projected area with the pristine synthetic reference. A ratio of at least 0.80 gives None detected. Below that, an explicit restriction/fusion input, mitral type IIIa or aortic type III mechanism permits the ordinal opening bins below. Without those features, a ring or nonzero-stiffness clip/suture requires a valid untouched baseline and a current/baseline opening ratio below 0.80; the category then uses that baseline ratio, not the pristine ratio. Otherwise the result is Indeterminate. Redundant prolapsing tissue can overlap in projection without true obstruction, so a low projected opening alone cannot establish stenosis or prove that a repair caused it.

Suspected regurgitation first requires valid geometry, a positive ejection budget, forward geometric capacity above the 0.01 L/min numerical floor and an uncapped reverse/forward capacity ratio. Invalid evidence, zero budget or a raw capacity ratio above 9 makes the result Indeterminate. With resolved evidence, None detected requires both a closed-phase excess leak proxy at or below 0.5% of annular area and modeled reverse/gross forward flow k/(1+k) at or below the original 1% teaching tolerance. If either floor is exceeded, the category uses the modeled reverse/gross fraction. A gap within its sampling floor cannot conceal substantial modeled return. This capacity-derived index depends on prescribed loading and geometry; it is not a measured regurgitant fraction, EROA or lesion-specific clinical cutoff.

The untreated Barlow example therefore has an indeterminate stenosis category when only redundant projected coverage suggests narrowing. Its suspected regurgitation category comes from resolved modeled return burden, not from prolapse alone. Stenosis categories remain geometry-based at zero ejection budget; regurgitation categories become indeterminate. Changing a positive budget alone scales flows without changing these categories. The rules do not alter prescribed pressure, solved tissue mechanics or the shared circulation budget.

Category thresholds

Apply these bins only after the eligibility checks above. They are original ordinal conventions for this prototype; clinical grading requires integrated valve-specific assessment.

Read the measurements

Hover a result for its method and units. Evaluate the cardiac phase and numerical status before comparing.

Case format and safeguards

Version 1 synthetic-case JSON stores provenance, units, coordinate system, baseline anatomy, alternative plans, complete operation histories and cursors, material and pressure inputs, optional echo measurements and wall-motion scores, mechanism metadata, solver settings, phase, camera, chamber envelopes, markings and results. It excludes DICOM images, segmentation and image-derived surfaces. Import accepts this synthetic format only, validates active and redo history, limits file size and rejects invalid units, nonfinite values, unsupported operations or attachment references. Image-surface export is a separate geometry-only format, not a mechanical-case import. Named G4 device identities persist with their repair operation; a legacy clip with no device identity retains its generic single-pair constraint. Invalid device identities or a valve/device mismatch are rejected.

Editing changes the calculation key. Results with a different key are not current. A browser worker keeps calculations off the rendering thread; request IDs reject superseded replies. The untouched baseline never inherits repair operations. Numerical inputs are available alongside viewport picking, and the viewer supports keyboard rotation and zoom. The active editor keeps up to 30 plan snapshots for Undo/Redo of revisions and removals; these temporary stacks are not part of saved JSON. Saved operation sequences and their cursor remain replayable after import. New edits clear the corresponding redo path. Switching plans or starting a new case resets temporary editor history. editor-history.ts validates every replay boundary, including undone operations, before restoring a plan or removing an edit; dependency failures leave the accepted plan unchanged.

Verification is not clinical validation

Synthetic-model checks cover finite indexed geometry, shared scallop boundaries, retained attachments, atomic rejected edits, fixed native rest lengths, tension-only behavior, load response, deterministic recalculation, case round trips, stale keys, forced nonconvergence and access gating. Image tests use synthetic pixels to check spatial calibration, stack rejection, source preservation, seeded connectivity, mask edits and surface topology. These checks verify implementation properties, not whether a valve was correctly segmented. Benchmarks and release verification are retained with the project.

Future validation needs independently segmented imaging, bench closure/contact measurements under recorded loads, mesh and solver convergence studies, material sensitivity, uncertainty propagation and blinded comparison with observed repairs. Clinical planning requires a substantially higher-fidelity validated model and governance. Published valve-modeling work informs the architecture; it does not validate this implementation.

Next milestones and imaging

Next: robust cut remeshing and stitched boundary reconstruction, general leaflet contact, moving annular/papillary boundaries and measured material models. Then extend tricuspid repair and add semilunar plication/commissural procedures and replacement with documented device data.

A future coupled-circulation adapter must distinguish prescribed and resulting pressure/flow, document any PAWP-as-LA approximation, and conserve flow. A nonlinear FE/FSI backend can implement the existing solver boundary without replacing the editor.

The current local image workflow provides source measurements and user-reviewed intensity masks with editable surfaces for compatible calibrated stacks. It does not identify valve anatomy automatically, decode vendor-private 3D echo or register image-derived geometry to a mechanical model. A future ReconstructionManifest-based pipeline must preserve modality, units, frame, phase, registration, mesh identities, observed versus inferred anatomy, uncertainty, review and source hashes.

Proposed pipeline: validate formats → segmentation and clinician correction → landmarks and registration → surface reconstruction → simulation mesh/attachment quality checks → phase correspondence → independent validation. SlicerHeart offers valve segmentation/analysis and FEM export, including synthetic inferred chords and VTK output. Prefer VTK plus explicit coordinate/units/provenance metadata; unstructured STL alone cannot preserve these semantics. Vendor-specific echo formats need separate compatibility checks.