A Newly Developed Miniaturized Heart-Lung Machine—Expression of Inflammation in a Small Animal Model * 1 Heike Schnoering, † 1 Jutta Arens, *Estella Terrada, *Joerg S. Sachweh, *Maximilian Runge, †Thomas Schmitz-Rode, †Ulrich Steinseifer, and *Jaime F. Vazquez-Jimenez *Department of Pediatric Cardiac Surgery, Medical Faculty; and †Department of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany Abstract: Cardiopulmonary bypass may cause severe inflammatory reactions and multiorgan failure, especially in premature and low-weight infants. This is due in part to the large area of contact with extrinsic surfaces and the essential addition of foreign blood. Thus, we developed a new miniaturized heart-lung machine (MiniHLM) with a total static priming volume of 102 mL (including arterial and venous lines) and tested it in a small animal model. Seven Chinchilla Bastard rabbits were perfused with the MiniHLM (dynamic priming volume 127 mL). Seven animals serving as a control were perfused using Dideco Kids and a Stöckert roller pump (modified dynamic priming volume 149 mL). The rabbits were anesthetized and sternotomized, followed by cannulation of the aorta and the right atrium. The aorta was clamped for 1 h. Blood for examination of inflammation (TNF-a, IL-1b, IL-6, IL-8, and IL-10) and blood gas analysis were taken before skin incision, 5 min before opening of the aorta, 15 min after opening of the aorta, and 4 h after the initiation of cardio- pulmonary bypass. The parameters of inflammation were expressed by means of the comparative C T method (DDCT method). After gradual reduction of perfusion with the HLM, the heart was decannulated, and the sternum was closed. All rabbits were successfully weaned from cardio- pulmonary bypass. Blood gas analysis was unremarkable in all cases. Foreign blood was not administered. Although statistical significance was not achieved, there was a reduced expression of inflammatory markers in the MiniHLM group. The newly developed MiniHLM proto- type was tested successfully in a small animal model in terms of technical function and expression of inflammation. Upcoming tests with the industrially manufactured MiniHLM may reveal the advantages of the MiniHLM in comparison with the conventional HLM. Key Words: Animal model—Cardiopulmonary bypass—Heart-lung machine—Inflammation—Pediatrics. An estimated 0.8% of neonates is born with a con- genital heart defect of varying complexity, approxi- mately half of which require open heart surgery during the first year of life (1). These operations are made possible with the use of a heart-lung machine (HLM). Although there have been attempts to make the implementation of HLMs safer and to lessen the risk of complications involved (2), little has changed in the HLMs used on children (3) since the first successful application of an HLM by Gibbon in 1953 (4). The current method of extracorporeal circulation used in pediatric patients employs standard HLMs with downsized components (5–7). Although this equipment provides adequate cardiopulmonary support during the surgical procedure, it entails a proportionally large area of contact with foreign material (8). Consequently, there is an inherent risk of complications in infants, especially those born with a low birth weight and/or premature. Of particular concern are damage to the coagulation system and acute inflammatory reactions in response to the doi:10.1111/j.1525-1594.2010.01146.x Received July 2010; revised August 2010. Address correspondence and reprint requests to Dr. Heike Schnoering, Department of Pediatric Cardiac Surgery, University Hospital, RWTH Aachen University, Pauwelsstr. 30, 52057 Aachen, Germany. E-mail: hschnoering@ukaachen.de Presented in part at the 6th International Conference on Pedi- atric Mechanical Circulatory Support Systems and Pediatric Car- diopulmonary Perfusion held May 6–8, 2010 in Boston, MA, USA. 1 Both authors contributed equally to the manuscript. Artificial Organs 34(11):911–917, Wiley Periodicals, Inc. © 2010, Copyright the Authors Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc. 911