We thank Dr Firstenberg for his letter regarding indications and contraindications for extracorporeal membrane oxygenation (ECMO) that were discussed in our article “The Role of Echocardiography in the Management of Patients Supported by Extracorporeal Membrane Oxygenation.” Dr Firstenberg’s letter has highlighted one of the key areas within the extracorporeal life support (ECLS) domain, that being who should receive this complex, expensive, but potentially lifesaving therapy. This decision is often a difficult one and necessitates a multidisciplinary approach, with input from the treating cardiologist or pulmonologist, intensivist, anesthesiologist, and cardiothoracic surgeon.

The initiation of ECMO support may result from a number of different clinical scenarios. First, ECMO may be electively considered before a planned procedure. In this controlled situation, one has the ability and time to obtain consensus through detailed review of all relevant data with the team members involved. Examples could include consideration before elective high-risk percutaneous coronary intervention or transcatheter aortic valve replacement. The second circumstance in which ECMO is considered involves management of an acutely critically ill patient, for which time is of the essence and decisions will be made with some information unobtainable in the given time frame. This makes the decision to initiate ECMO a complex one, and as Dr Firstenberg quite rightly points out, it is made on a case-by-case basis. This is particularly pertinent for venoarterial (VA) ECMO, for which this modality may be considered as a bridge to decision or bridge to ventricular assist device implantation or transplantation. In these situations, VA ECMO may be acting as a bridge to definitive therapy, for which there are well-accepted absolute contraindications. By extension, one can consider the absolute contraindications of cardiac transplantation as also absolute contraindications to VA ECMO, even when a life is acutely at risk. This is when astute judgment and experience are required to make a critical decision on what represents the best option between appropriate patient management and futility of care, in a challenging environment.

Similarly, we concur with Dr Firstenberg that the indications for ECMO are broadening and that successful outcomes are being achieved in patients with conditions previously considered contraindications to ECMO. Generally speaking, these are being reported as case reports and/or very small series by centers with extensive experience. We hope that discussions such as this will advance the knowledge of the ECMO community into what is possible today and what may be possible tomorrow.

With regard to pulmonary hypertension, we also agree that right ventricular function and cardiac output can improve with correction of acidosis and improvement in oxygenation, particularly in severe sepsis, and we have seen several such successful cases. Recently, a group from Papworth Hospital in the United Kingdom described the use of salvage ECMO to facilitate pulmonary thromboendarterectomy and continued support in the postoperative period.

In end-stage pulmonary hypertension for which maximal medical therapy has failed, bridging to transplantation with ECLS may be undertaken in carefully selected patients. ECLS options could include venovenous ECMO with inotropic support of the right heart and continuation of pulmonary vasodilator therapy, central VA ECMO, or a pulmonary artery–to–left atrium pumpless circuit with an oxygenator. An animal model of pulmonary hypertension with right ventricular failure has been described using venovenous ECMO with the creation of an atrial septal defect to provide an oxygenated right-to-left shunt as a means of providing oxygenated systemic blood flow. Additionally, there is the confounding factor of organ availability, particularly if heart-lung transplantation is required, for which waiting times may be longer than ideal for patients supported on a short-term modality such as ECMO. In such settings, each center must judge its ability to deal with such cases and the specific patient indications within a hospital and government regulatory framework.

With regard to other examples raised, we congratulate Dr Firstenberg on the outcomes he and his team have achieved with high-risk patients using ECMO. Given that there is still debate on the role of venovenous ECMO in isolated respiratory failure, we suggest that the use of ECMO in high-risk salvage cases should be undertaken with great care in highly selected patients at experienced centers.

The final point we would like to emphasize is the significant institutional variation that exists regarding the approach to patients requiring ECMO. This variation is a consequence of differences in experience and expertise within a unit providing ECLS. High-volume, experienced centers with a full range of cardiac and thoracic therapeutic options immediately available will have a substantially different approach to the decision as to in whom and when ECMO should be started, as opposed to smaller centers with less experienced ECMO programs. One could argue that these smaller centers should have more tightly defined sets of indications and contraindications.

In short, Dr Firstenberg’s comments and experiences concur with our own. His letter focuses on one of the most challenging and complex aspects in ECMO therapy, and one which an imaging physician is often not privy to, namely, the decision as to which patients should receive this complex, expensive, but potentially lifesaving therapy.