TissueDB/Simulators/Superficial Temporal Artery-Middle Cerebral Artery Bypass Trainer

The STA-MCA Bypass Trainer is an end-to-side superficial temporal artery (STA) to middle cerebral artery (MCA) microvascular anastomosis simulator described by Akdag et al. (2024) in World Neurosurgery 190:e665–e674. The trainer pairs a 3D-printed hemispheric cranial model and silicone parenchyma with avian arterial simulants — turkey brachial artery representing the donor STA, and chicken brachial artery representing the recipient MCA-M4 segment. Three embedded Force Sensitive Resistors (FSRs; Interlink 0.500", Lake Forest, California) record brain-contact pressure during the procedure. A closed recirculation loop (VicTsing 80 GPH aquarium pump, 1000 mL reservoir, Rifocin-dyed water) simulates arterial flow, with manometer-driven pressure challenge to 200 mmHg for leak-test verification.

Build sequence traceable to Akdag et al. (2024) main text and figures. The 3D cranium, silicone parenchyma, FSR sensor subsystem, and circulation loop are built once at session start; vessel samples and Rifocin water are per-trial consumables.

1. Using a 3D printer, print a hemispheric cranial mould sized to a left cerebral hemisphere.
2. Pour silicone into the mould and allow it to cure to form a cerebral parenchyma model of the left hemisphere.
3. Using a surgical drill, perform a left frontotemporoparietal craniotomy on the hardened silicone model to expose the region where the STA-MCA anastomosis will be performed.
4. Position the cranial model at 45° rotation to the right and 30° extension to simulate the intraoperative head position for cerebral bypass surgery.

1. Solder the (+) and (−) terminals of each of three 0.500-inch Interlink Force Sensitive Resistors (FSR S1, S2, S3) with a 10-kΩ pull-down resistor on the (−) terminal.
2. Connect each FSR to a microcontroller analog input configured for 5 V supply.
3. Calibrate each sensor by applying a stepped load of 0–200 N and recording the voltage response; fit the three polynomial curves: sensor 1, y = 0.0039x² − 0.2749x + 14.299; sensor 2, y = 0.004x² − 0.2166x + 10.313; sensor 3, y = 0.0032x² − 0.1791x + 9.208.
4. Configure the microcontroller to convert analog voltage to force (N) using each sensor's polynomial and to trigger an audible alert each time a configured touch-force threshold is crossed.
5. Position the three calibrated sensors (S1, S2, S3) around the sylvian fissure on the silicone parenchyma model — corresponding to the frontal and temporal lobes — and fix them securely.
6. Connect all three sensors to a data receiver for continuous recording of touch-event timing and magnitude throughout the procedure.

1. Using dissection scissors, a scalpel, clamps, and forceps, expose the brachial artery, vein, and nerve bundle in a turkey wing (donor vessel for STA simulation).
2. Using a calliper, measure and dissect a 5–6 cm segment of the turkey brachial artery (diameter 1.0–1.5 mm) while preserving its integrity.
3. Under the surgical microscope, ligate all microvascular branches of the turkey brachial artery with 10-0 sutures so that only the main branch remains patent.
4. Dissect and separate the adventitia from the turkey brachial artery.
5. Repeat the dissection, length measurement, branch-ligation, and adventitial dissection steps on a chicken wing brachial artery (recipient vessel for MCA-M4 simulation; approximately 1 mm diameter).

1. Place the proximal end of the turkey STA simulant into an intravenous cannula and secure it with a 3-0 vicryl suture.
2. Place the distal end of the chicken MCA simulant into an intravenous cannula and secure it with a 3-0 vicryl suture.
3. Connect each cannula to an intravenous infusion set with an adjustable flow regulator.
4. Place the proximal ends of both infusion sets into a 1000-mL beaker reservoir.
5. Fill the beaker with water and add Rifocin (rifampicin) ampules to dye the water red for leak visualisation.
6. Connect the VicTsing 80 GPH aquarium pump outlet via a third intravenous infusion set to the reservoir, creating a closed-loop circulation from STA simulant → anastomosis → MCA simulant → beaker → pump → STA simulant.
7. Connect the pump to a power source and verify that liquid flows at a controlled speed through the STA simulant, through the (not-yet-anastomosed) MCA simulant, and back to the beaker.
8. Connect a perfusor and a calibrated manual manometer (mmHg) to the proximal end of the system; the manometer will be used post-anastomosis for leak-pressure titration.

1. Lay the prepared turkey brachial artery (STA simulant) so that it extends to the left temporal lobe of the silicone parenchyma.
2. Lay the prepared chicken brachial artery (MCA M4 simulant) so that it extends from the left frontal lobe to the sylvian sulcus.
3. Apply methylene blue to the vessel ends to aid vessel-wall identification under the microscope during anastomosis.
4. Verify that the three FSR sensors remain securely fixed around the sylvian fissure and that the circulation system remains connected.

1. Perform a fish-mouth arteriotomy at the distal end of the turkey STA simulant (donor vessel).
2. Place one microvascular clip at the proximal end and one at the distal end of the chicken MCA simulant to isolate the recipient segment.
3. Using a scalpel, perform a linear arteriotomy on the chicken MCA simulant between the two clips.
4. Using an interrupted-suture technique, place the first 2 sutures at the "heel" and "toe" of the joined arteries, stitching outside-to-inside on the STA and inside-to-outside on the M4.
5. Continue the interrupted-suture anastomosis with 10 additional sutures, alternating between the front and back walls as is standard for end-to-side STA-MCA bypass.
6. Use either 9-0 polyamide suture (Ethilon 6/6; 5.0 mm round-bodied) or 10-0 polyamide suture (Ethilon 6; 3.8 mm round-bodied) per trial protocol; instrument choice is either (a) micro needle holder + micro forceps or (b) bilateral micro forceps.
7. Record the total anastomosis completion time, the number of sensor touches (automatic from the data receiver), and the suture type + instrument combination used.

1. With the anastomosis complete, release the two microclips from the chicken MCA simulant.
2. Activate the aquarium pump to initiate Rifocin-dyed circulation through the completed anastomosis.
3. Confirm anastomotic continuity (visible red flow from STA simulant through anastomosis into MCA simulant).
4. Clamp the distal ends of the system to maintain pressure, and use the perfusor to pressurise the system.
5. Titrate systolic pressure from hypotensive (<120 mmHg) through normotensive (120 mmHg) up to a maximum hypertensive value of 200 mmHg.
6. Record whether leakage occurs, the mean pressure at leak onset, and the number of leak points at each pressure level. If no leakage occurs at 200 mmHg, classify the anastomosis as patent.
7. If leakage is detected, identify and count leak points; determine whether the leak is at an interrupted suture (technique) or at the vessel wall (tissue failure).

• Anastomotic continuity confirmed under Rifocin-dyed circulation — pass/fail
• Leak-test patency at 200 mmHg systolic — pass/fail (Akdag 2024 reports 66.70% patent across the 24-trial series)
• FSR data receiver records continuous touch events with no signal dropouts — pass/fail
• Manometer pressure titration covers full hypotensive–normotensive–hypertensive range — pass/fail

1. Power down the aquarium pump and disconnect the power source.
2. Remove the turkey and chicken brachial artery samples (single-trial consumables); discard via standard biological-waste protocol.
3. Empty the beaker of Rifocin-dyed water. Rinse the beaker, infusion sets, and pump-outlet line with clean water to prevent Rifocin staining and to remove biological residue.
4. Inspect all microsurgical instruments for damage; clean per institutional instrument-care protocol (no acidic-media corrosion issue here, unlike the Cikla grapefruit-juice environment).
5. Inspect the silicone parenchyma model for FSR displacement or sensor-wiring damage; re-anchor sensors if needed. The silicone parenchyma is reusable across many trials.
6. For the next trial, repeat Phase 3 (new vessel harvest and preparation) and Phase 4 step 5 (refill beaker with fresh Rifocin-dyed water). The 3D cranium, silicone parenchyma, and FSR sensor subsystem are reused in place.

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