Understanding Differential Hypoxemia in ECMO Patients

In this episode of SoCCC Pre-Rounds, Dr. Simon Parlow sits down with Dr. Jason Katz,  advanced heart failure and transplant cardiologist, critical care leader, and president of the Society of Critical Care Cardiology, to dive into the real-world challenges of managing VA ECMO at the bedside.

ECMO can be life-saving, but it’s also one of the most complex tools in the ICU. Dr. Katz breaks down what every trainee needs to know: the difference between VV and VA ECMO, when and how to decide who’s a candidate, and why every cannulation must come with an “exit strategy.” He shares practical insights on navigating the first critical days, staying vigilant for complications like Harlequin syndrome, and when left ventricular venting makes sense.

If you’ve ever felt overwhelmed by the idea of managing a patient on VA ECMO, this episode gives you a clear, practical roadmap so you feel more prepared the next time you see an ECMO consult roll into the CICU.

Key Takeaways

• The difference between VV and VA ECMO and why VA supports both the heart and lungs.

• Classic indications for VA ECMO: when to consider it for refractory cardiogenic shock or cardiac arrest.

• How to decide if your patient has a viable exit strategy, bridge to recovery, bridge to transplant, or bridge to decision.

• Harlequin syndrome (differential hypoxemia): What it is, how to detect it, and what to do about it.

• Pearls on left ventricular venting and unloading: when to consider a balloon pump, Impella, or atrial septostomy.

• [00:00:00] Introduction  

• [00:00:45] Episode sponsor & guest introduction  

• [00:01:57] Defining and differentiating VV and VA ECMO  

• [00:04:47] Indications and patient selection for VA ECMO  

• [00:06:49] VA ECMO as a bridge and contraindications  

• [00:10:02] Early management and complications of VA ECMO  

• [00:14:14] Differential hypoxemia (Harlequin syndrome)  

• [00:18:18] Left ventricular venting and unloading  

• [05:28] "If there's one thing that is consistent about places that are using VA ECMO is that there is no consistency." — Dr. Jason Katz

• [10:18] "You need to think about how you're going to get off the device, again, whether you're hoping for recovery or it's a bridge to an exit strategy like durable VAD or transplantation." — Dr. Jason Katz

• [13:48] "Transplantation as an exit strategy. But again, the longer these patients are on these devices, the ECMO is certainly the case. But for every temporary MCS device, the longer they're on these devices, the higher their risk for getting one of these complications." — Dr. Jason Katz

• [19:40] "Everything that unloads the heart or unloads the left ventricle is going to vent the left ventricle, but not everything that vents the left heart will necessarily unload or reduce the myocardial oxygen consumption." — Dr. Jason Katz

Dr. Jason Katz

Associate Chief of Cardiology, Bellevue Hospital; Program Director for Advanced Heart Failure and Transplant Fellowship, NYU; President, Society of Critical Care Cardiology. Nationally recognized leader in advanced heart failure, critical care cardiology, and mechanical circulatory support.

Resources and Links

Become a member of the Community: ⁠⁠https://www.soccc.org/subscribe⁠⁠

Dr. Jason Katz

• https://x.com/jasonkatzmd?lang=en

• https://hfsa.org/jason-n-katz-md-mhs

Dr. Simon Parlow

Supported By:

This episode is made possible by unrestricted support from Zoll LifeVest — thanks for keeping high-impact education free for our community.

Disclaimer

This podcast is not medical advice, just candid, practical discussions about what your hosts do every day in the CICU. Always consult your supervising team and current guidelines before applying any interventions.