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Time dependence of endothelium-mediated vasodilation by intermittent antegrade warm blood cardioplegia
D Curro1, G Bombardieri, C Barilaro
1Department of Cardiology, Catholic University, Rome, Italy.
Background:
The technique of intermittent antegrade warm blood cardioplegia (IAWBC) exposes the heart to brief periods of normothermic ischemia. This may impair endothelial function in coronary arteries.
Methods:
Three cardioplegic technique were tested in porcine hearts arrested for 32 to 36 minutes and reperfused for 30 minutes: IAWBC, antegrade cold blood cardioplegia (ACBC), and antegrade cold crystalloid cardioplegia (ACCC). In the hearts arrested with IAWBC, three different intervals of ischemia were used: three 10-minute intervals (IAWBC1), two 15-minute intervals (IAWBC2), and one 30-minute interval (IAWBC3). Rings from the coronary arteries were used to evaluate in vitro the contractile responses to U46619 and the relaxant responses to bradykinin, A23187, and sodium nitroprusside.
Results:
All six groups (treatment groups and control group) displayed similar responses to U46619 (30 nmol/L) and nitroprusside. In the IAWBC1, IAWBC2, AND ACBC groups, endothelium-dependent relaxations to bradykinin and A23187 were preserved compared with controls, whereas those of the ACCC and IAWBC3 groups were significantly impaired (bradykinin: control, 8.72 +/- 0.07; IAWBC1, 8.73 +/- 0.03; IAWBC2, 8.65 +/- 0.05; IAWBC3, 8.30 +/- 0.07 [p < 0.05]; ACBC, 8.50 +/- 0.03; ACCC, 8.25 +/- 0.09 [p < 0.05]; A23187: control, 7.07 +/- 0.08; IAWBC1, 7.07 +/- 0.06; IAWBC2, 7.04 +/- 0.03; IAWBC3, 6.64 +/- 0.01 [p < 0.05]; ACBC, 6.80 +/- 0.05; ACCC, 6.60 +/- 0.08 [p < 0.05]; nitroprusside: control, 6.19 +/- 0.1; IAWBC1, 6.19 +/- 0.07; IAWBC2, 6.03 +/- 0.03; IAWBC3, 6.08 +/- 0.05; ACBC, 6.04 +/- 0.2; ACCC, 6.05 +/- 0.03; all values are expressed as the negative logarithm of the concentration producing 50% of the maximal response).
Conclusions:
Myocardial preservation with IAWBC with ischemic intervals of 15 minutes or shorter does not alter the endothelium-dependent relaxation to bradykinin or A23187 in porcine coronary arteries, but these responses are significantly impaired by ACCC and IAWBC with an ischemic interval of 30 minutes.