Imaging insights in veno-venous and veno-arterial extracorporeal membrane oxygenation (ECMO): CT protocols, underlying pathophysiology, and main complications

Abstract: Extracorporeal membrane oxygenation (ECMO) is a vital life support technique employed in patients experiencing pulmonary or cardiopulmonary failure. This procedure entails the use of a pump to replace heart function and an oxygenator to ensure adequate blood oxygenation. ECMO systems are categorized into two main configurations: veno-venous (VV) and veno-arterial (VA) circuits. VV-ECMO is employed for isolated respiratory failure, while VA-ECMO provides temporary mechanical circulatory support for patients with cardiogenic shock or cardiac arrest. A less common alternative, veno-arterial-venous (VAV) ECMO, may be used in complex cases, reducing left ventricular afterload, leading to an improvement of pulmonary edema. Imaging plays a pivotal role in ECMO management, particularly in confirming proper cannula placement, detecting malposition or migration, and identifying complications such as hemorrhage, thrombosis, vascular injury, or infections. Chest X-ray serves as the first-line imaging modality, while computed tomography (CT) is essential for a more detailed evaluation in cases of suspected complications. Tailored CT protocols, adapted to specific ECMO configurations, contrast injection site, cardiac output, and ECMO flow rate, are essential to account for possible ECMO-induced hemodynamic changes and ensure accurate diagnosis. This review provides a comprehensive guide for radiologists, offering detailed descriptions of ECMO system configurations, cannula positioning, and imaging techniques. It highlights the importance of understanding ECMO-specific challenges and outlines strategies to optimize imaging protocols, including modifications in contrast administration and flow-rate adjustments, ultimately improving diagnostic accuracy and patient outcomes. Critical relevance statement: Radiologists must be familiar with VV- and VA-ECMO systems, utilize tailored CT protocols, and apply non-invasive imaging modalities to assess cannula positioning and complications, ensuring accurate evaluation and management of critically ill patients relying on these advanced life-support techniques. Key Points: ECMO is a life support technique used in patients with pulmonary or cardiopulmonary failure. CT protocols should be customized based on the study indication, ECMO configuration, contrast injection site, cardiac output, and ECMO flow rate. Non-invasive imaging is crucial for evaluating cannula placement and identifying complications. Approximately 50% of ECMO patients develop complications, the most frequent being hemorrhage, thromboembolic disease, renal failure, sepsis, and vascular injury.