TissueDB/Simulators/Grapefruit Distal Anterior Cerebral Artery Bypass Simulator

The Grapefruit Distal Anterior Cerebral Artery Bypass Simulator is a low-cost model, built from locally available materials, for practising side-to-side distal anterior cerebral artery (dACA) bypass — a deep, narrow-field microvascular anastomosis.^[1] A large grapefruit is cut with two pole-to-pole rind incisions to open a cavity between its sections that recreates the deep interhemispheric fissure. Two vessels — chicken-wing brachial arteries or thin synthetic tubing — are cannulated, laid parallel in the central column, and joined side-to-side with 10‑0 nylon under microscope magnification. A small aquarium pump drives dyed water through the vessels in a closed loop, so any leak in the anastomosis is immediately visible. The model needs no special laboratory facilities.

Build sequence from Cikla et al. (2020) Materials and Methods.

1. Choose a large grapefruit (12–15 cm diameter) and rest it on the stabilising base.
2. Make two parallel pole-to-pole incisions in the rind with a No. 11 scalpel, axis to axis, marking off a region covering about one-fifth of the surface.
3. Cut along both lines down to the border between pith and skin only — do not cut into the flesh.
4. Slice one of the two marked rind strips lengthways to make a strip about 2 cm wide, and set it aside for Phase 2.
5. Dissect bluntly along the natural groove between the two grapefruit sections to open the cavity that represents the interhemispheric fissure.

Verification: the cavity opens cleanly to the central column without tearing the flesh.

1. Remove the skin from a chicken wing and harvest the brachial artery as a 5–6 cm segment (for biologic vessels); strip the adventitia about 1 mm from each end. Use a fresh wing where possible — vessel quality is higher than from thawed wings — and harvest close to the time of use.^[2]
2. Fit each vessel end over a 2.5 cm angiocatheter (or micropipette) tip and tie it on with 3‑0 nylon. Prepare a second matched vessel the same way. Self-cannulated 2 mm synthetic tubing can be used instead.
3. Remove the grapefruit stem from the central column with forceps, clearing the path the vessels will occupy.
4. Lay the two vessels parallel in the central column of the grapefruit.
5. Replace the 2 cm rind strip from Phase 1 over the vessels with its pith side facing them, forming a buried floor.

Verification: the two vessels sit parallel and accessible in the central column.

1. Connect the vessels to two nasal cannulas: the ventral-pole cannula splits into two afferent channels (one per vessel), the dorsal-pole cannula takes the two efferent channels.
2. Fill the one-litre reservoir with about 250 mL of water and red dye and submerge the aquarium pump in it. Run the pump's outlet tubing to the inflow cannula and turn it on to confirm a closed circulating loop. The recirculation method follows the previously described Wisconsin model.^[3]

Verification: water circulates through both vessels in a closed loop with no leak before practice begins.

1. Steady the grapefruit on its base with the fissure facing the table. Carefully remove the thin layer of pith covering the outer flesh (this represents the arachnoid and pia mater) and clear the tissue down to the natural groove, separating the sections with small retractors. Descend slowly toward the central column, taking care not to tear the flesh — tearing represents iatrogenic injury of the cortex. Successful retraction reveals the pair of vessels about 4 cm below the pith; hold the sections open with small elastic stays.
2. Place a temporary aneurysm clip proximal and distal to the planned bypass on each vessel to stop the flow.
3. Incise each occluded vessel along the bypass markings and join the two vessels side-to-side with 10‑0 nylon under the microscope.
4. Remove the clips and watch the suture line under circulation: leaking dyed water means the anastomosis needs further sutures until it runs dry.

Verification: with the clips off, water flows through both vessels and the anastomosis holds without leaking into the surrounding flesh.

• Remove the clips, check the anastomosis for leaks and add sutures until dry.
• Disconnect the vessels and discard used chicken-wing segments; reusable synthetic tubing can be kept.
• Wash all instruments immediately — the acidic grapefruit juice corrodes them.
• Refresh the reservoir water, and replace the grapefruit when its flesh is too damaged to retract without tearing.

• Procedures other than deep-field microvascular anastomosis — the model reproduces the dACA bypass field specifically.
• Training that needs true blood behaviour or thrombosis — the circuit uses water, which the authors note reduces perfusion realism and does not model clotting.