Letter to the Editor: Minimizing arterial injury and confirming arterial flow during normothermic machine perfusion

To the editor,The timely report by Bodzin et al.1 describes different scenarios of arterial injury recognized during back-table preparation of the liver for connecting to normothermic machine perfusion (NMP). The third case with a missed replacement of the right hepatic artery, which ultimately became a level 3 injury (liver discard), is especially important. Previous reports of procurement liver injuries stratified by levels are likely underreported and could be impacted by reporting bias for level 1 and 2 injuries, especially if the procurement team is from the accepting program.2–4 European studies report higher rates of arterial injury compared with the United States and a higher risk of hepatic artery thrombosis (HAT), retransplant, and graft loss despite repair. In addition, the long-term impact of arterial stenosis and biliary ischemia following delayed reconstruction/repair is poorly recognized and reported. With increasing donation after cardiac death (DCDD), the risk of injury increases due to unrecognized aberrant anatomy and shear injury during rapid cannulation.2–4 Normothermic regional perfusion (NRP) allows easier cannulation and assessment of variant arterial anatomy but needs validation. Whether a dedicated organ procurement organization (OPO) or NMP can provide donor surgeons with the means to reduce injury rates needs to be evaluated. NMP parameters do offer an opportunity to potentially recognize the missed arterial inflow and evaluate the reconstructed, replaced/accessory artery after connecting to NMP.1 However, prolonged non-arterial perfusion may result in graft discard.1 Similarly, unrecognized absent arterial perfusion to 1–2 liver segments (accessory artery) can lead to focal bile duct ischemia that presents late and goes unreported. The authors’ use of ultrasonography (USG) Doppler for assessment of arterial flow is especially pertinent with the increasing use of DCDD grafts and older donors. The following measures are proposed to prevent arterial injury and assess arterial perfusion on NMP: Pre-donation contrast CT/MRI for identification of variant arterial anatomy and arterial atherosclerosis. USG Doppler or audible handheld continuous-wave Doppler needs evaluation and validation—right anterior and posterior Glissonian pedicles with both sides of the fissure for the ligamentum teres. Assessment of indocyanine green (ICG) arteriography with handheld near infrared (NIR) detectors to check arterial inflow to all segments (simultaneous ICG clearance for functional assessment).5