After birth dramatic decreases in cardiac malonylCoA levels result in the rapid maturation of fatty acid oxidation. We have previously demonstrated that the decrease in malonyl CoA is due to increased activity of malonyl CoA decarboxylase (MCD), and decreased activity of acetyl CoA carboxylase (ACC), enzymes which degrade and synthesize malonyl CoA, respectively. Decreased ACC activity corresponds to an increase in the activity of 5Ј-AMP activated protein kinase (AMPK), which phosphorylates and inhibits ACC. These alterations are delayed by myocardial hypertrophy. As rates of fatty acid oxidation can influence the ability of the heart to withstand an ischemic insult, we examined the expression of MCD, ACC, and AMPK in the newborn human heart. Ventricular biopsies were obtained from infants undergoing cardiac surgery. Immunoblot analysis showed a positive correlation between MCD expression and age. In contrast, a negative correlation in both ACC and AMPK expression and age was observed. All ventricular samples displayed some degree of hypertrophy, however, no differences in enzyme expression were found between moderate and severe hypertrophy. This indicates that increased expression of MCD, and the decreased expression of ACC and AMPK are important regulators of the maturation of fatty acid oxidation in the newborn human heart. T he adult heart has an extremely high energy demand which is met by the oxidation of fatty acids, accounting for 60 -80% of cardiac ATP (ATP) production (1-5). Glycolysis, glucose oxidation, and lactate oxidation are responsible for the remainder of ATP production (2). Interestingly, cardiac energy substrate preference differs between the fetal and neonatal heart. In the fetal heart blood levels of fatty acids are low (6) and the heart has a low circulatory workload and meets its energy demands from glycolysis and lactate oxidation (6 -8). At birth, major cardiovascular changes occur, including a reduction in pulmonary vascular resistance and closure of the ductus arteriosus and foramen ovale. These changes are coupled to an increase in peripheral vascular resistance, and an increased workload on the newborn heart. With circulating substrate and hormonal changes there is a switch in the energy substrate preference of the heart, from glucose and lactate metabolism to fatty acid oxidation (6 -8).Although plasma fatty acid levels rapidly rise to levels seen in the adult immediately after birth (6), newborn rabbit studies have shown that the heart undergoes a transition from oxidizing glucose to oxidizing fatty acids during the 7 d immediately after birth (9,10). The time frame responsible for the maturation of fatty acid oxidation in the human newborn heart is not yet known.The increase in fatty acid oxidation after birth in the newborn rabbit heart is related to dramatic decreases in cardiac malonyl CoA levels (10,11). Malonyl CoA is a potent inhibitor of carnitine palmitoyl transferase-1 (CPT-1), the rate limiting enzyme of mitochondrial fatty acid uptake (12). Acetyl CoA Carboxy...

Extracorporeal membrane oxygenation (ECMO) is a method to provide temporary cardiac and respiratory support to critically ill patients. In recent years, the role of ECMO in emergency departments (EDs) for select adults has increased. We present the dramatic case of a 29-year-old man who was placed on venoarterial ECMO for cardiogenic shock and respiratory failure following collapse and protracted ventricular fibrillation cardiac arrest in our ED. Resuscitation efforts prior to ECMO commencement included 49 minutes of virtually continuous cardiopulmonary resuscitation (CPR), 11 defibrillations, administration of numerous medications, including a thrombolytic agent, while CPR was ongoing, percutaneous coronary intervention and stenting for a mid-left anterior descending coronary artery dissection and thrombotic occlusion, inotropic support, and intra-aortic balloon pump counterpulsation. Over the next 48 hours following ECMO commencement, the patient's cardiorespiratory function rapidly improved, and he was discharged home 9 days after admission with no neurologic sequelae. The history, indications, and increasing role of ECMO in a range of conditions, including cardiac arrest, are reviewed. RÉ SUMÉL'oxygé nation extracorporelle sur oxygé nateur à membrane (OEOM) est un moyen de fournir une assistance cardiaque et respiratoire temporaire à des patients gravement malades. Le rô le de l'OEOM a gagné du terrain chez certains adultes aux services des urgences (SU) au cours des derniè res anné es. Sera exposé ici le cas spectaculaire d'un homme de 29 ans, soumis à l'OEOM veino-arté rielle pour un choc cardiogé nique et une insuffisance respiratoire suivant un collapsus et un arrê t cardiaque causé par un accè s prolongé de fibrillation ventriculaire, qui est survenu au SU de l'hô pital. Les moyens de ré animation mis en oeuvre avant le dé but de l'OEOM comprenaient des manoeuvres de ré animation cardiorespiratoire (RCR) pratiqué es de faç on quasi continue durant 49 minutes; 11 tentatives de dé fibrillation; l'administration de nombreux mé dicaments, dont un thrombolytique, pendant que se poursuivaient les manoeuvres de RCR; une intervention coronarienne percutané e et la pose d'une endoprothè se pour une dissection du segment moyen de l'artè re interventriculaire anté rieure et une oblité ration thrombotique; un soutien inotrope et la contrepulsion par ballon intra-aortique. Au cours des 48 heures suivant le dé but de l'OEOM, l'é tat cardiorespiratoire du patient s'est amé lioré rapidement, et celui-ci est retourné chez lui 9 jours aprè s son admission, et ce, sans souffrir de sé quelles neurologiques. Seront passé s en revue l'historique, les indications et le rô le de plus en plus grand de l'OEOM dans diverses affections, dont l'arrê t cardiaque.