Comparison of Warm and Tepid
Re-perfusion Temperature for Myocardial Protection by Ischemic
Preconditioning |
(The Second Department of Surgery, Nihon University
School of Medicine, Tokyo, Japan)
Hiroyuki Hirose |
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Recently, ischemic preconditioning
(IPC) for myocardial protection in heart surgery, has been used
intensively. However, no data are available concerning the effect
and influence of re-perfusion temperature during IPC. To estimate
the effectiveness of re-perfusion temperature during IPC, we
performed an experiment using pigs. Twenty male pigs (40-50kg
in body weight) were used. After establishing cardiopulmonary
bypass (CPB), IPC was made, cross-clamping the ascending aorta
twice for 3 min and performing re-perfusion for 5 min. According
to the re-perfusion temperature, we divided this model into four
groups as follows; 37 of the re-perfusion temperature with IPC
(warm IPC, n5), 37 without IPC (warm NIPC, n5),
32 with IPC (tepid IPC, n5) and 32 without IPC (tepid
NIPC, n5). After the IPC procedure, all the hearts underwent
global ischemia by cross-clamping for 15 min under ventricular
fibrillation, and re-perfusion with 32 blood temperature was
done for half hour. We measured myocardial levels of adenosine
triphosphate, troponin-T, serum nitrous oxide, and other myocardial
enzymes. After sacrificing animals, biopsy of the left ventricular
free wall was made, and its histological changes were evaluated
by scanning electron microscopy (SEM). Blood sampling was made
before CPB, at the end of IPC, end of global ischemia, 10 and
30 min after re-perfusion. In warm IPC, adenosine significantly
increased, and serum troponin-T was significantly lower than
other groups. The myocardium of warm IPC showed a normal SEM
image, while ischemic damage was revealed in other groups. These
results suggested that warm IPC induced effective myocardial
protection. however tepid IPC did not protect the myocardium.
@Jpn. J. Cardiovasc. Surg. 30F237-241 (2001) |
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