Om. Bical et al., Does warm antegrade intermittent blood cardioplegia really protect the heart during coronary surgery?, CARDIOV SUR, 9(2), 2001, pp. 188-193
Objective: Intermittent antegrade blood cardioplegia (IABC) has been standa
rdized as a routine technique for myocardial protection in coronary surgery
. However, if the myocardium is known to tolerate short periods of ischemia
during hypothermic arrest, it may be less tolerant of warm ischemia, so th
e optimal cardioplegic temperature of intermittent antegrade blood cardiopl
egia is still controversial. The aim of this study was to compare the effec
ts of warm intermittent antegrade blood cardioplegia and cold intermittent
antegrade blood cardioplegia on myocardial pH and different parameters of t
he myocardial metabolism.
Methods: Thirty patients undergoing first-time isolated coronary surgery we
re randomly allocated into two groups: group 1 (15 patients) received warm
(37 degreesC) intermittent antegrade blood cardioplegia and group 2 (15 pat
ients) received cold (4 degreesC) intermittent antegrade blood cardioplegia
. The two randomization groups had similar demographic and angiographic cha
racteristics. Total duration of cardiopulmonary bypass (108 +/- 17 and 98 /- 21 min) and of aortic cross-clamping (70 +/- 13 and 65 +/- IS min) were
similar. The cardioplegic solutions were prepared by mixing blood with pota
ssium and infused at a now rate of 250 ml/min for a concentration of 20 mEq
/l during 2 min after each anastomosis or after 15 min of ischemia. Intramy
ocardial pH was continuously measured during cardioplegic arrest by a minia
ture glass electrode and values were corrected by temperature. Myocardial m
etabolism was assessed before aortic clamping (pre-XCL), 1 min after remova
l of the clamp (XCL off) and 15 min after reperfusion (Rep) by collecting c
oronary sinus blood samples. All samples were analyzed for lactate, creatin
e kinase (MB fraction), myoglobin and troponin 1. Creatine kinase and tropo
nin 1 were also daily evaluated in peripheral blood during 6 days post-oper
atively.
Results: The clinical outcomes and the haemodynamic parameters between the
two groups were identical. In group 1, XCL, off and Rep were associated wit
h higher coronary sinus release of lactate (5.5 +/- 1.8 and 2.2 +/- 0.5 mmo
l/l) than in group 2 (2.0 +/- 0.7 and 1.6 +/- 0.3 mmol/l, P < 0.05). Mean i
ntramyocardial pH was lower in group 1 (7.23 +/- 0.08) than in group 2 (7.6
5 +/- 0.30, P < 0.05). There were no significant differences between the tw
o groups with respect of creatine kinase (MB fraction) either after Rep or
during the post-operative period. Lower coronary sinus release of myoglobin
was detected at Rep in group 1 (170 +/- 53 mug/l) than in group 2 (240 +/-
95 mug/l, P < 0.05). At day 1, a lower release of troponin I was found in
group 1 (0.11 +/- 0.07 g/ml) compared to group 2 (0.17 +/- 0.07 ng/ml, P <
0.05).
Conclusion: With regards to similar clinical and haemodynamic results, myoc
ardial protection induced by warm IAEX is associated with more acidic condi
tions (intramyocardial pH and lactate release) and less myocardial injury (
myoglobin and troponin 1 release) than cold intermittent antegrade blood ca
rdioplegia during coronary surgery. (C) 2001 The International Society for
Cardiovascular Surgery. Published by Elsevier Science Ltd. All rights reser
ved.