Myocardial ischemia is more important than the effects of cardiopulmonary bypass on myocardial water handling and postoperative dysfunction: A pediatric animal model

Jonathan R. Egan, Tanya L. Butler, Andrew D. Cole, Avetis Aharonyan, David Baines, Neil Street, Manchula Navaratnam, Oliver Biecker, Carla Zazulak, Carol G. Au, Yee Mun Tan, Kathryn N. North, David S. Winlaw

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

Objectives: Low cardiac output state is the principal cause of morbidity after surgical intervention for congenital heart disease. Myocardial ischemia-reperfusion injury, apoptosis, capillary leak syndrome, and myocardial edema are associated factors. We established a clinically relevant model to examine relationships between myocardial ischemia, edema, and cardiac dysfunction and to assess the role of the water transport proteins aquaporins. Methods: Sixteen lambs were studied. Seven were control animals not undergoing cardiopulmonary bypass, and 9 underwent bypass. Six had 90 minutes of aortic crossclamping with blood cardioplegia and moderate hypothermia. The remaining 3 underwent cardiopulmonary bypass without aortic crossclamping. Hemodynamic and biochemical data were recorded, and myocardial edema, apoptotic markers, and aquaporin expression were determined after death. Results: The group undergoing cardiopulmonary bypass with aortic crossclamping had a low cardiac output state, with early postoperative tachycardia, hypotension, increased serum lactate levels, and impaired tissue oxygen delivery (P < .05) compared with the group undergoing cardiopulmonary bypass without aortic crossclamping. The lambs undergoing cardiopulmonary bypass with aortic crossclamping had increased myocardial water (P < .05) compared with those not undergoing cardiopulmonary bypass and a 2-fold increase in aquaporin 1 mRNA expression (P < .05) compared with those not undergoing cardiopulmonary bypass and those undergoing cardiopulmonary bypass without aortic crossclamping. Conclusions: A temporal association between hemodynamic dysfunction, myocardial edema, and increased aquaporin 1 expression was demonstrated. Cardiopulmonary bypass without ischemia was associated with minimal edema, negligible myocardial dysfunction, and static aquaporin expression. Ischemic reperfusion injury is the main cause of myocardial edema and myocardial dysfunction, but a causal relationship between edema and dysfunction remains to be proved.

Original languageEnglish
Pages (from-to)1265-1273.e2
JournalJournal of Thoracic and Cardiovascular Surgery
Volume136
Issue number5
DOIs
Publication statusPublished - Nov 2008
Externally publishedYes

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