Heart rate control strategies in patients on veno-venous extracorporeal membrane oxygenation support

Background: Despite veno-venous extracorporeal membrane oxygenation (VV-ECMO) support, hypoxemia may persist due to venous shunting past the ECMO circuit into diseased lungs. Heart rate (HR) control therapy in patients with elevated cardiac output (CO) is one strategy to improve the ratio of ECMO flow to CO and reduce shunting. Methods: This retrospective study examined VV-ECMO patients between June 2019 and June 2023 that received ⩾1 HR control agent within 10 days post-cannulation. Efficacy outcomes included trends in hemodynamics, oxygenation, and ventilator and ECMO parameters within 72 h after HR control initiation. Safety outcomes included incidence of hypotension or bradycardia requiring intervention. Results: Thirty-nine patients were included. The most common HR control strategy was initiation of esmolol infusion with transition to an oral beta-blocker after a median overlap of 6 days. Patients experienced reductions in HR and CO; however, there were no substantial changes in oxygenation parameters. Adverse events were minimal, with only two cases of hypotension requiring intervention. Conclusions: While HR control therapy was well tolerated and effectively reduced HR, it did not seem to improve oxygenation. Larger prospective studies should be designed to ascertain the role of HR control strategies in VV-ECMO patients with elevated CO experiencing refractory hypoxemia.