We have read the review article entitled “Controversies in ECMO: Immediate versus Watchful Waiting for VA-ECMO Venting” by Cavayas and colleagues, published in the Special Issue of Invited Presentations: Adult: Mechanical Circulatory Support: Invited Expert Opinions of JTCVS Open December 2021. We congratulate the authors for this nice review article and, at the same time, provide some personal comments.

The authors described the pathophysiology of left ventricle (LV) overload and correctly underlined the role of the preload in this complex mechanism. LV preload has been often underestimated as an important determinant of LV distension during venoarterial (VA) extracorporeal life support (ECLS). Indeed, the patient’s venous return usually exceeds the ECLS drainage and subsequently passes through the pulmonary circulation. As a consequence, the residual transpulmonary blood flow and bronchial venous return may not be counterbalanced by the reduced LV ejection due to impaired contractility and retrograde ECLS-generated blood flow toward the aortic valve, leading to LV dilation and pulmonary congestion.

A meticulous fluid–balance management should be strongly recommended. Continuous renal-replacement therapy may be adopted to avoid fluid overload when diuretics resistance occurs.

Furthermore, the authors highlighted the urgent need of a common LV overload definition during VA ECLS and clearly stated its absence in the literature. On one hand, we strongly believe this gap should be immediately solved to better analyze and elucidate the ongoing research on this topic. On the other hand, a common LV overload definition has been already provided. Among 184 peripheral VA ECLS retrospectively investigated at the Maastricht University Medical Center, we developed a multiparametric approach to appropriately detect and monitor the LV-related hemodynamics and potential overload appearance during VA ECLS.

First of all, this definition considered direct and undirect parameters, which should be always assessed in relationship with the others. None of them is sufficient for diagnosing the LV overload.

Echocardiography plays a central role. This evaluation should quickly achieve an anatomical/functional overview of the heart. Besides the dimensions, volumes, and LV ejection fraction, the echocardiogram must include the aortic valve inspection.