Review the indications for veno-arterial ECMO as it relates to pulmonary thrombectomy through the lens of a Pulmonary Embolism Response Team
Examine the components of an ECMO circuit, including proper cannula location and circuit pitfalls
Summarize the current outcome data on ECMO and percutaneous intervention for high-risk pulmonary embolism
Background: High-risk pulmonary embolism may necessitate veno-arterial extracorporeal membrane oxygenation (ECMO) for cardiorespiratory support, either prior or during the setting of pulmonary thrombectomy. The American Heart Association recommends early ECMO support rather than salvage therapy when indicated in this patient population. As ECMO utilization for pulmonary embolism increases, vascular and interventional radiologists' familiarity with the indications, placement, pitfalls, and data related to ECMO and mechanical circulatory support is crucial to patient care.
Clinical Findings/Procedure Details: In addition to the primary drainage and return cannulas, ECMO circuits include a central pump, an oxygenator, a controller, a heat exchange, and monitors for hemodynamics. Veno-arterial ECMO is typically cannulated via femoral artery and veins, with often an additional arterial distal perfusion lower extremity cannula to minimize limb ischemia. The drainage catheter diameter is the flow-rate limiting component, with larger cannulas selected to support a flow rate equivalent with a cardiac index frequently > 5 L/m2/min in adults. Arterial catheter monitoring is paramount to assess for complications such as North-South syndrome. In the setting of high-risk pulmonary embolism, a large meta-analysis found decreased mortality rates with catheter-directed interventions in the setting of ECMO.
Conclusion and/or Teaching Points: Veno-arterial ECMO confers a survival benefit in the setting of high-risk pulmonary embolism. As the utilization of mechanical circulatory support increases in this pathology, vascular and interventional physicians must be comfortable with the indications, system components, complications, and multidisciplinary management of ECMO in the setting of high-risk PE.
