Drawn to scale on paper; the screen view is resized to fit. Solid circle = fenestration, dashed = cuff footprint; the mark beside each fen is its strut check for the map shown: ✓ clear, ◆ tucked or trimmed, ▲ check, ✕ breaks a rule, ○ not checked.
Artery
IVD (AVD)
Distance down
Arc
Fen mm
Push out
Strut mm
Vessel
Prev intervention
Grafts
Notes
Yellow cells place the fens, as on the Excel: the top vessel's adjusted distance down, each other vessel's absolute distance down, and the reference vessel's adjusted arc. The rows sort top-down when a distance is entered. Print at Scale 100% on Letter paper.
How to use Fensmith
Experimental. Not medical advice. Not FDA cleared.
Fensmith is an experimental planning aid. It is not a medical device and has not been cleared or approved by the FDA or any other regulator. Nothing in it is medical advice, and it is not endorsed by or affiliated with Cook Medical or Terumo Aortic. Physician modification of an endograft is off-label and carries serious risk.
The device geometry, sizes and rules were taken from public documents and measurements and may contain errors, may not match the device in your hands, and may change between device revisions or lots. Check every assumption, number and output against the device's current IFU, your own measurements of the device on the back table, the patient's imaging and your institution's protocols before any real-world use. You are responsible for every clinical decision. Use it only as a second check, never as the only one. It comes with no warranty of any kind.
Choose a layout above the plan: Walk-through takes one step at a time with notes on each; Plan sheet lays the whole plan out like the Excel plan sheet, with the same yellow cells. Both edit the same plan: switch any time.
Pick the graft (device and size).
Fill in each vessel as in the Excel: the clock face (e.g. 12:45 or 2:30) and the distance below the top vessel from the plan tab's Distance down (Absolute). The rows sort top-down when a distance is entered; ✕ removes a vessel (3-vessel plans), and + Add vessel adds one.
Diameters: enter the AVD, the aortic diameter at the vessel. The IVD, what the graft will open to, fills in as the smaller of the AVD and the graft's diameter there (grey); type over it, e.g. with the narrowest diameter along the stent ring. The arc uses IVD + 1, as the Excel. When they differ the plan shows "IVD (AVD)", e.g. 28 (36), and a gap over 5 mm from the graft to the ostium is flagged.
Reference vessel: arcs are measured from the SMA unless you choose another (a celiacomesenteric trunk, an occluded celiac, an IMA case). Its fen gets the 3 mm rule and Best fit builds around it.
Graft branches (rarely needed): set a vessel's type to Outer or Inner to sew a branch over its fen. Enter which way it points (↓ down or ↑ up), its diameter, its (stent) length, and the gap from its outlet to the ostium. Those set the fen: an outer branch's fen is the gap plus the length from the ostium (the notes: a 2 to 2.5 cm branch leaving about 1 cm to cannulate, so the fen 3.5 to 4 cm above the ostium); an inner branch's outlet is its fen, at the ostium unless you type a gap. The fen moves there (arcs, strut checks and Best fit follow it), the maps draw the tube (outer solid, inner dashed, its open end heavier) and a dotted circle at the ostium, and on the plan sheet and the build sheet the Absolute and Adjusted lines give the ostium while a Branch fen line below them gives the fen. A blank fen size is the branch's diameter + 1. In an Alpha taper the tube leans toward the zero line on the map, as the struts do: the graft is narrower lower down, so the same clock position is fewer mm from the zero line. On the graft the fen is directly above the ostium, at the vessel's clock. Checks: the room for an outer branch (AVD − IVD at least its diameter, or a diameter-reducing tie or an inner branch), an outlet gap under 5 mm (amber: little room to cannulate), a tube over another fen, a tube off the fabric, and on the Treo an inner branch within 10 mm of the flow divider.
Position the fenestrations: set the top vessel's distance from the top of the fabric and the reference vessel's adjusted arc. Use − and + to move every fen 1 mm at a time, protecting the reference fen first: the checks suggest the nearest adjusted arc that clears it, or a depth when no arc at that depth does. If a renal then lands on a strut, use its Push out box rather than moving everything.
Best fit (its own tab): set the range of the top vessel's distance (blank = the current distance ±10 mm; on the Alpha never under 40 mm of fabric above the top fen, on the Treo never less seal than now) and click Find best fit. It lists the three best positions (per ring phase on the Treo): every fen clear first, then a fen tucked into a peak or valley or trimmed along a strut, then a renal pushed out under 3 mm, then a fen near a point. Use sets the top vessel's distance, the reference vessel's adjusted arc and each renal's Push out. The heat map shows every position it tried: click a cell to use it.
Treo: enter where the contralateral gate points (clock face). Both ring phases are checked; the back table decides which applies. A 7 mm SMA fen cannot clear 3 mm in both phases at the usual SMA levels, so plan the SMA adjusted arc for one phase: the checks give the arc for the other, and the build sheet lists the adjusted arcs to use if the back table shows it. On the 20 mm Treo no position gives a 7 mm SMA fen 3 mm in either phase.
Print at Scale 100% on Letter paper: the build sheet, landscape on paper (laid out like the Excel plan tab, without the checks; it is turned sideways on its page, so the preview shows it sideways and any printer prints it landscape), then the true-size maps. Under each clock face the build sheet gives the C-arm angles for it: the bullseye view (down the vessel's origin) and the perpendicular view (the origin in profile), as LAO or RAO from AP (30 degrees an hour). Under its picture (and under the map on screen) it gives the crowns per stent and the distance around the graft from crown to crown and crown to valley (the middle of a valley), as on the Excel sheets. Measure 0 to 100 on the left ruler of each map page: it must be 100 mm. Nothing depends on color, so a greyscale printer is fine.
Save (or Ctrl+S) writes a copy of this planner with the plan inside. Double-click that file to reopen the plan, like a patient's Excel file. A saved plan keeps the planner version it was made with; to move it to a newer planner, open it with Open… there.
Strut marks: ✓ clear, ◆ tucked or trimmed, ▲ check, ✕ breaks a rule, ○ not checked. Flags: red breaks a planning rule, amber check it, info for awareness. Rules from the technical notes: the SMA (the reference vessel) at least 3 mm from any strut (3 mm or more is green: 4 is rarely achievable); never a strut across a fen, since the fabric is never cut around a strut (push a renal out with Push out, or shift every fen), though suturing around a strut next to a fen is fine; a fen inside the V of a peak or valley, up to 1 mm into its struts, can be tucked (teardrop toward the apex, sewn around the struts), and one running up to 1 mm into a strut along its length can be trimmed to stay on one side and sutured around it (both shown teal ◆); a strut across a renal that a push out under 3 mm clears is amber, otherwise red; a fen within 1.5 mm beyond the point of a peak or valley is less ideal (sewing there pinches the fabric); cuffs (dashed) not overlapping; at least 40 mm of fabric above the highest fen; the IVD no wider than the graft at that level (the notes cap the arc diameter at the graft's nominal diameter); a gap over 5 mm from the graft to the ostium (AVD − IVD). Most plans show some amber: only a small part of the graft keeps a 7 mm fen 3 mm clear of every strut.
Treo: a ring crown or valley can face the gate on any graft, so every fen is checked in both ring phases, and each phase's map marks the fens for that phase (the build sheet's picture and the transparency page show the worse of the two).
Try an example: (the 3-vessel example has a common celiac-SMA trunk, the "SMeliac", as its reference vessel; the branch example an outer branch to the right renal in a 40 mm aorta). They are composites of past plans with the numbers changed: no patient.
Arcs are computed exactly like the Excel: clock hours from 12 × π × (IVD + 1) / 12, rounded to whole mm, measured from the SMA (or the reference vessel chosen).