Distribution of oxygenated blood by transseptal left atrial cannulation during lung support in the open-chest model

The hemodynamic characteristics and anatomic configuration of the aortic root determine the extent of coronary bed filling by the desaturated blood ejected by the left ventricle during conventional lung support with extracorporeal membrane oxygenation (ECMO), unless turbulence is created close to the coronary ostia by high-flow bypass ratios (greater than 80% of cardiac output) or ascending aorta cannulation. Using a total right heart bypass preparation, we studied the effect of returning blood transseptally into the left atrium upstream to the coronary arteries by means of a specially designed double-lumen cannula inserted via the jugular vein. Desaturated blood was used in six dogs ventilated with 100% oxygen (Group A), and oxygenated blood was used in 10 hypoxic dogs (Group B). We observed homogeneous mixing of oxygenated and desaturated blood at wide ranges of bypass flow ratios (20 to 80%) as determined downstream to the left atrium, i.e., left ventricle, coronary artery branch, root of the aorta, and descending thoracic aorta. Adequate coronary oxygenation (PO2 greater than or equal to 60 mm. Hg) was obtained with 40% of cardiac output oxygenation, a flow that could be met with a single superior vena cava (SVC) cannula through the major lumen of such a cannula. Total avoidance of high-pressure arterial cannulation and homogeneous distribution of oxygenated blood, regardless of the bypass flow ratio, by this technique are obvious advantages not available with conventional ECMO cannulations.