Angiography in the Setting of Extracorporeal Membrane Oxygenation (ECMO): What an Interventional Radiologist Needs to Know

1. Understand the differences in ECMO circuit types and cannulation access sites


2. Review the physiologic differences and impact of ECMO on catheter angiography


3. Tips and tricks to optimize clinical and procedural success

There are two types of ECMO circuits: venovenous (VV) and venoarterial (VA).  VV ECMO withdraws venous blood and subsequently returns oxygenated blood to the venous system.   In contrast, VA ECMO withdraws venous blood and returns oxygenated blood to the arterial system.  VA ECMO can be further classified into central and peripheral based on the arterial cannulation site.  In central VA ECMO, there is direct cannulation of the ascending aorta and blood flow follows the native antegrade pathway.  However, in peripheral VA ECMO, which is more commonly utilized, a peripheral artery is cannulated and blood flows retrograde within the thoracic aorta.

The most common venous access sites include the femoral and internal jugular veins.  The most common peripheral arterial access sites include the femoral artery, occasionally carotid, subclavian, or axillary.  Often, these critically ill patients require additional arterial or venous access points for monitoring lines or other mechanical cardiac support devices such as impella or intra-aortic balloon pump.

While on ECMO, anticoagulation is used to prevent thrombotic complications.  However, sustained anticoagulation combined with acquired coagulopathy in critically ill patients leads to significant risk for bleeding events.  Due to limited arterial access site availability in combination with the non-physiologic blood patterns, angiography on ECMO patients can be challenging.

Clinical Findings/Procedure Details:

This exhibit will review the role and challenges of angiography in critically ill patients on ECMO.  This will start with reviewing ECMO itself including indication, cannulation access sites, blood flow patterns, and bleeding complications.  The challenges in work up and management of bleeding complications will be discussed including the role and limitations of diagnostic imaging.  Finally, angiography itself will be discussed in detail including technical and diagnostic challenges in the setting of limited access point availability and non-physiologic blood flow. Various angiographic pictures of patients on ECMO will be provided.

Conclusion and/or Teaching Points:

1. Patients on ECMO can have non-physiologic blood flow


2. Work up and management of these patients can be difficult and pose clinical and procedural challenges


3. Understanding all this is important to optimize procedural and clinical success, ultimately improving patient care