Author: Anila B. Elliott, MD - C.S. Mott Children’s Hospital - University of Michigan
A 12-year-old male with viral myocarditis develops malignant arrhythmias and suffers a cardiac arrest. After return of spontaneous circulation (ROSC) is achieved, he is placed on VA ECMO for ongoing cardiogenic shock. Over the next few hours, his arterial pulse pressure progressively diminishes. What is the MOST APPROPRIATE next step?
EXPLANATION
Veno-arterial extracorporeal membrane oxygenation (VA ECMO) has a significant role in rescue therapy, especially in those with congenital or acquired cardiac pathology. ECMO has been shown in both pediatric and adult populations to improve post-operative survival, allowing for adequate end-organ perfusion while waiting for cardiac recovery. However, inflow cannula position into the arterial system allows for retrograde aortic flow that can lead to elevated left ventricular afterload, especially when native ventricular contractility is poor1,2,3. This may reduce aortic valve opening, elevating left ventricular end-diastolic pressure (LVEDP), subsequently increasing left atrial pressure and causing pulmonary congestion, all of which ultimately worsens myocardial function.
In practice, progressive loss of pulsatility after VA ECMO initiation is a key warning sign for inadequate LV ejection and evolving LV distention. Common presenting signs to consider left-sided decompression include decreased pulse pressure (less than 10-15mmHg), rising filling pressures (PCWP greater than 18), increasing LV dimensions, stasis of blood in the LV cavity (“smoke” or spontaneous ECHO contrast on TTE), low LV outflow tract velocity time integral (LVOT VTI less than 10cm), persistently closed aortic valve, pulmonary edema, or refractory arrhythmias1,2,3.
Therefore, with this patient’s diminished pulse pressure a few hours after initiation of ECMO, the next best step is TTE to assess left-sided distention/aortic valve opening and consideration of left-sided decompression if indicated (Answer C).
Left atrial decompression can be performed percutaneously and has been associated with improved in-hospital outcomes in pediatric congenital cardiac patients on ECMO4. Other therapeutic options include intra-aortic balloon pump or Impella placement, but their use remains limited in the pediatric population due to size constraints.
Although cannula position is important, malposition typically presents with difficulty achieving targeted flow or abnormal circuit pressures (Answer A). Coronary angiography (Answer B) may be indicated if ongoing coronary ischemia was thought to be the initial insult precipitating arrest, however, it would not be the initial step in working up a narrow pulse pressure.
Therefore, the correct answer is C, to obtain a TTE and evaluate for left sided distention indicating decompression.
REFERENCES
1. Cevasco, M., Takayama, H., Ando, M., et al. Left ventricular distention and venting strategies for patients on venoarterial extracorporeal membrane oxygenation. J Thorac Dis 2019; 11(4): 1676-1683
2. Ezad, SM., Ryan, M., Donker, DW., et al. Unloading the left ventricle in venoarterial in ECMO: In Whom, When, and How? Circulation 2023; 147(16):1237-1250
3. Lüsebrink, E., Binzenhöfer, L., Kellnar, A., et al. Venting during venoarterial extracorporeal membrane oxygenation. Clin Res Cardiol 2022; 112(4):464-505
4. Sperotto, F., Polito, A., Amigoni, A., et al. Left atrial decompression in pediatric patients supported with extracorporeal membrane oxygenation for failure to wean from cardiopulmonary bypass: a propensity-weighted analysis. J Am Heart Assoc 2022; 11(23):e023963