O. Irtun et D. Sorlie, HIGH CARDIOPLEGIC PERFUSION-PRESSURE ENTAILS REDUCED MYOCARDIAL RECOVERY, European journal of cardio-thoracic surgery, 11(2), 1997, pp. 358-362
Objective: The cardioplegic solution is often given at high how and pr
essure following aortic clamping to ensure rapid diastolic arrest. Wit
h standard setup in clinical practice, it is easy to exceed 200 mmHg i
n the aortic root. To investigate whether cardioplegic solution delive
ry pressure has an influence on myocardial protection, intermittent in
fusions of crystalloid cardioplegia were given at two different pressu
res using an in vivo pig model. Methods: Fourteen pigs (48-57 kg) were
put on cardiopulmonary bypass, aorta-clamped (2 h) and 500 ml St. Tho
mas' cardioplegia (4 degrees C) was delivered antegradely at either 75
mmHg (group 1, n = 7) or 175 mmHg (group 2, n = 7) pressure via a 9-F
aortic root cardioplegic needle. Every 20 min, 100 ml cardioplegia we
re delivered at either one of the two pressures. After 2 h, the aorta
was unclamped and the hearts reperfused. Attempts were made to wean th
e pigs from bypass following 20 min reperfusion or, if they were faili
ng, after 40 min. If failing once again, the pigs were reperfused for
the last 20 min on the heart-lung machine. Results: Hearts in group 1
(n = 7) needed significantly longer time to stop after aortic clamping
(38 +/- 9 s) than did group 2 hearts (n = 7) (21 +/- 5 s) (P = 0.043)
. In group 1, all pigs were weaned from bypass, whereas in group 2 onl
y 2 out of 7 pigs were able to sustain circulation without cardiopulmo
nary bypass (P = 0.01), and then with lower hemodynamic performances.
At the end of cardiac arrest, group 1 had significantly higher adenosi
ne triphosphate (19.41 +/- 1.1 mu mol/g dry weight and 15.05 +/- 1.8 m
u mol/g dry weight, respectively) (P = 0.05) and significantly lesser
fall in energy charge than group 2 (0.02 +/- 0.01 and 0.05 +/- 0.02, r
espectively) (P = 0.05). Also at the end of reperfusion, group 1 had s
ignificantly higher adenosine triphosphate (16.54 +/- 1.4 mu mol/g dry
weight and 12.53 +/- 0.95 mu mol/g dry weight, respectively) (P = 0.0
16) than group 2. Conclusions: Despite a swifter diastolic cardiac arr
est, the high cardioplegic solution delivery pressure caused significa
ntly poorer postischemic recovery than a moderate pressure with the sa
me amount of cardioplegic solution. (C) 1997 Elsevier Science B.V.