ECMO Veno-Arterial (VA) ECMO Management 2 — Questions and Answers
Question 1: Which hemodynamic finding is most consistent with the 'North-South syndrome' (Harlequin syndrome) in peripheral VA ECMO?
- Hypoxic lower body with well-oxygenated upper body
- Hypoxic upper body with well-oxygenated lower body (Correct answer)
- Global hypoxia despite adequate ECMO flow
- Differential cyanosis of the left arm only
Correct answer: Hypoxic upper body with well-oxygenated lower body
In Harlequin syndrome, retrograde ECMO flow oxygenates the lower body while the patient's own failing heart delivers desaturated blood to the upper body and coronary arteries.
Question 2: A patient on peripheral VA ECMO develops limb ischemia in the cannulated leg. What is the primary intervention?
- Increase ECMO flow to improve perfusion
- Place a distal perfusion cannula in the superficial femoral artery (Correct answer)
- Switch to central cannulation immediately
- Administer IV heparin bolus and observe
Correct answer: Place a distal perfusion cannula in the superficial femoral artery
A distal perfusion cannula (DPC) inserted antegrade into the superficial femoral artery restores distal limb perfusion while maintaining ECMO support.
Question 3: What does a persistently elevated pulmonary artery pressure on VA ECMO most likely indicate?
- Adequate LV unloading
- LV distension due to insufficient venting (Correct answer)
- Pulmonary embolism unrelated to ECMO
- Circuit recirculation
Correct answer: LV distension due to insufficient venting
Elevated PA pressures on VA ECMO suggest the left ventricle is distending because it cannot eject against the increased afterload imposed by the circuit.
Question 4: Which parameter best reflects native cardiac recovery during VA ECMO weaning trials?
- Mean arterial pressure at full ECMO flow
- Pulse pressure amplitude on arterial waveform (Correct answer)
- Central venous oxygen saturation
- ECMO pump RPM
Correct answer: Pulse pressure amplitude on arterial waveform
Increasing pulse pressure amplitude on the arterial waveform indicates the native heart is generating stroke volume, a key sign of myocardial recovery.
Question 5: In VA ECMO, the 'mixing cloud' refers to:
- Turbulence visible on ECMO circuit imaging
- The zone in the aorta where ECMO and native cardiac output blood mix (Correct answer)
- Air-blood interface in the oxygenator
- Clot formation at the venous cannula tip
Correct answer: The zone in the aorta where ECMO and native cardiac output blood mix
The mixing cloud is the aortic zone where retrograde oxygenated ECMO blood meets antegrade native cardiac output; its position determines differential oxygenation.
Question 6: A VA ECMO patient's ACT target is typically maintained between:
- 100–140 seconds
- 160–200 seconds (Correct answer)
- 220–280 seconds
- 300–360 seconds
Correct answer: 160–200 seconds
ACT is generally maintained at 160–200 seconds on VA ECMO to balance thrombosis prevention against bleeding risk.
Question 7: Which echocardiographic finding would prompt emergent LV venting in a VA ECMO patient?
- Hyperdynamic LV with LVEF >55%
- Spontaneous echo contrast in the LA
- Severely dilated, non-contracting LV with mitral regurgitation (Correct answer)
- Small pericardial effusion without tamponade
Correct answer: Severely dilated, non-contracting LV with mitral regurgitation
A severely dilated, non-contracting LV with MR indicates LV distension that can cause pulmonary edema and myocardial injury, requiring urgent venting.
ECMO Veno-Arterial (VA) ECMO Management 2
Which hemodynamic finding is most consistent with the 'North-South syndrome' (Harlequin syndrome) in peripheral VA ECMO?