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Background:Peripheral veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is used to support circulatory failure refractory to conventional therapy. However, data on the heart-ECMO interaction at different levels of ECMO blood flow during the immediate period after ECMO initiation are sparse. We evaluated the effects of varying ECMO blood flow rate on left ventricular systolic function.Methods:Adult patients who were supported by peripheral V-A ECMO in a tertiary referral center were recruited. Serial hemodynamic and cardiac performance parameters were measured by transthoracic echocardiogram within the first 48 hours after implementation of V-A ECMO. Measurements at 100%, 120%, and 50% of target blood flow (TBF) were compared.Results:A total of 45 patients were included, 32 (71.1%) were male, and the median age was 57 (50-64) years. The main indications for V-A ECMO were myocardial infarction 25 (55.6%) and myocarditis 6 (13.3%). With a decrease in extracorporeal blood flow from 100% to 50% of TBF, mean arterial pressure dropped from 75±18 to 67±20 mmHg (p2 (pConclusions:In the initial period of V-A ECMO support, left ventricular systolic function quantified bedside echocardiography was inversely related to ECMO blood flow rate. The heart-ECMO interaction should be considered when determining goals of ECMO flow after initiation.

A 79-year-old man, who had significant cardiovascular morbidities, presented with out-of-hospital respiratory arrest. He regained breathing after brief cardiopulmonary resuscitation by his paramedic son. After meticulous investigations, acute cardiovascular events and metabolic causes were ruled out while features of obstructive sleep apnoea were elicited. The findings on in-laboratory polysomnography were compatible with severe obstructive sleep apnoea, with unusually prolonged apnoea duration of up to 2.7 min which most likely accounts for the presentation as ‘respiratory arrest’. Thyroid function test for investigation of his weight gain confirmed hypothyroidism. His symptoms improved gradually after positive airway pressure therapy with bi-level support and thyroxine replacement. On further evaluation, his hypothyroidism is believed to be a complication of long-term amiodarone exposure. The case highlights that the combination of obstructive sleep apnoea and hypothyroidism can lead to catastrophic manifestation and the unusually long apnoea could be a feature prompting further workup for possible hypothyroidism.