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J Thorac Cardiovasc Surg 2009;137:1005-1011
© 2009 The American Association for Thoracic Surgery
Cardiopulmonary Support |
a Department of Cardiac Surgery, LK St Poelten, Austria
b Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna Medical University, Vienna, Austria
c Institute of Physiological Chemistry, Center of Physiological Medicine, Medical University Graz, Austria
d Department of Pathology, Vienna Medical University, Vienna, Austria
e Department of Pediatrics, Vienna Medical University, Vienna, Austria
Received for publication April 4, 2008; revisions received October 6, 2008; accepted for publication October 27, 2008. * Address for reprints: Bruno K. Podesser, MD, Ludwig Boltzmann Cluster for Cardiovascular Research, C/O Core Unit for Biomedical Research, Medical University of Vienna, Vienna General Hospital, Währinger Gürtel 18-20, 1090 Vienna, Austria. (Email: bruno.podesser{at}meduniwien.ac.at).
Objective: Ischemia/reperfusion injury caused by cardioplegic arrest is still a major challenge in patients with reduced left ventricular function. We investigated the effect of chronic versus acute administration of the selective endothelin-A receptor antagonist (ERA) TBC-3214Na during ischemia/reperfusion in failing hearts.
Methods: Male Sprague–Dawley rats underwent coronary ligation. Three days after myocardial infarction (MI), 19 randomly assigned animals (ERA chronic) were administered TBC-3214Na continuously with their drinking water, 29 MI rats received placebo, and 3 rats died during the observation period. Six weeks after infarction, hearts were evaluated in a blood-perfused working heart model during 60 minutes of ischemia and 30 minutes of reperfusion. In 14 MI rats, TBC-3214Na (ERA acute) was added to the cardioplegic solution during ischemia. Thirteen MI rats served as control.
Results: At a similar infarct size, postischemic recovery of cardiac output (ERA chronic: 91% ± 10%, ERA acute: 86% ± 11% vs control: 52% ± 15%; P < .05) and external heart work (ERA chronic: 90% ± 10%, ERA acute: 85% ± 13% vs control: 51% ± 17%; P < .05) was significantly enhanced in both TBC-3214Na–treated groups whereas recovery of coronary flow was only improved in ERA acute rats (ERA acute: 121% ± 23% vs ERA chronic: 75% ± 13%; control: 64% ± 15%; P < .05). Blood gas measurements showed enhanced myocardial oxygen delivery and consumption with acute TBC-3214Na therapy. Additionally, high-energy phosphates (phosphocreatine) were significantly higher and transmission electron microscopy revealed less ultrastructural damage under acute TBC-3214Na administration.
Conclusion: Acute endothelin-A receptor blockade is superior to chronic blockade in attenuating ischemia/reperfusion injury in failing hearts. Therefore, acute endothelin-A receptor blockade might be an interesting option for patients with heart failure undergoing cardiac surgery.
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