Hypothermic, closed circuit pericardioperfusion: a potential cardioprotective technique in acute regional ischemia

Heart Institute at Good Samaritan Hospital, Division of Cardiology, University of Southern California, Los Angeles 90017, USA.

OBJECTIVES: This study sought to determine whether infarct size can be reduced by hypothermic pericardioperfusion. BACKGROUND: We have shown that myocardial infarct size can be reduced by topical cooling of the heart. The present study tests whether myocardial cooling and protection can be produced by hypothermic pericardioperfusion using a catheter. METHODS: The catheter was sutured into the pericardial space of anesthetized rabbits. Beginning 30 min before coronary artery occlusion, the space was perfused with either chilled (n = 10) or body temperature (n = 10) fluid. The artery was occluded for 30 min and reperfused for 3 h. RESULTS: After 30 min of pericardioperfusion, myocardial temperature was reduced to 34.1 +/- 0.9 degrees C in chilled hearts compared with 38.9 +/- 0.4 degrees C in control hearts, p < 0.001, a reduction in myocardial temperature of approximately 5 degrees C. Risk areas were similar in both groups (32 +/- 4% left ventricle in cooled and 31 +/- 3% in control hearts, p = NS). However, infarct size in cooled hearts was significantly reduced by 49% (18 +/- 3% of risk area vs. 35 +/- 6%, p = 0.025). Tamponade did not develop, and there were no significant differences in heart rate, arterial pressure or body temperature between groups. CONCLUSIONS: A significant reduction in myocardial temperature, without the development of cardiac tamponade, can be attained using a pericardial catheter to cool the pericardial space. This reduction in temperature causes a significant reduction in necrotic damage. This technique might be used to cool and protect the heart as an adjunct to thrombolysis or during minimally invasive cardiac surgery.

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