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KMID : 0377519980230010001
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Chung-Ang Journal of Medicine
1998 Volume.23 No. 1 p.1 ~ p.10
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Enhancement of ventricular function and infarct size reduction by ischemic preconditioning
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Yoon Sun-Hwa
Kim Hyun
Kim Ho-Dirk
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Abstract
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It has been demonstrated that brief periods of ischemia and reperfusion (ischemic preconditioning, IP) enhance recovery of post-ischemic contractile dysfunction and reduce incidences of reperfusion-induced arrhythmia or infarct size after a subsequent sustained ischemia. In the present study, the authors attempted to examine whether reduction in infarct size could be afforded by IP and how the infarct size changed in accordance to the geometry of the heart. Hearts isolated from New Zealand White rabbits (1.5-2.0 kg body weight) were perfused with Tyrode solution by Langendorff technique. After stabilization of baseline hemodynamics, the hearts were subjected to 45-minute global ischemia followed by 120-minute reperfusion with IP (IP group) or without IP (control group, n=12). IP was induced by single episode of 5-minute global ischemia and 10-minute reperfusion (IP1, n=13). Left ventricular function including developed pressure (LVDP), dP/dt, heart rate, left ventricular end-diastolic pressure (LVEDP) and coronary flow (CF) was measured. Iinfarct size was determined by staining with TTC (tetrazolium salt) and planimetry. Data were analyzed by paired or unpaired t=tests and linear regression. Regular cardiac rhythm was restored within 4 minutes on reperfusion in the IP hearts, whereas it was done after 5 minutes in the control. The LVDO, dP/dt and CF were higher in the IP hearts than in the control, and especially the recovery of LVDP was maintained at 90% of the baseline value. In contrast, the increase of LVEDP was much higher in the control (31-38 mm Hg), while that in the IP hearts was 22-28 mm Hg. Infarct size was significantly reduced in the IP hearts compared to the control; infarct was evident within the first half of the cardiac tissue slices perpendicular to the long axis of the heart parallel from apex to base of the heart, however, infarct was not evident in the second half of the heart. These results indiate that in isolated Langendorff-perfused rabbit heart model, IP could improve post-ischemic contractile dysfunction and it has an infarct size-limiting effect.
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KEYWORD
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Infarct size, ischemic preconditioning, ischemia and reperfusion, isolated rabbit heart
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