Decreased Incidence of Low Output Syndrome with a Switch from Tepid to Cold Continuous Minimally Diluted Blood Cardioplegia in Isolated Coronary Artery Bypass Grafting

OBJECTIVES:

The optimal temperature for blood cardioplegia remains unclear.

METHODS:

A
retrospective analysis was performed on 138 patients undergoing
isolated myocardial revascularization by a single surgeon in our
institution over a period of 2 years. Patients operated on early in the
study period received tepid (29°C) continuous minimally diluted blood
cardioplegia (minicardioplegia), delivered in an antegrade continuous
fashion. Later, our surgeon began using cold (7°C) blood
minicardioplegia in all patients. Data pertaining to clinical outcomes
and postoperative biochemical data were obtained, and the two groups
were compared.

RESULTS:

Low cardiac output syndrome,
defined as the need for intra-aortic balloon pump counter pulsation or
inotropic medication for haemodynamic instability, was more frequent in
the tepid cardioplegia group than in the cold cardioplegia group (16.0
vs 2.4%, P = 0.006). There was no difference in the maximal serum
creatine kinase MB between the two groups (cold 25.4 ± 3.21 μg/ml vs
tepid 36.5 ± 7.10 μg/ml, P = 0.62), in the rates of perioperative
myocardial infarction (cold 1.2% vs tepid 6.0%, P = 0.15) and the need
for postoperative insertion of an intra-aortic balloon pump (cold 4.8%
vs tepid 0.0%, P = 0.3). There was no other statistically significant
difference between the two groups in the measured parameters.

CONCLUSIONS:

A
higher rate of low cardiac output syndrome in the tepid cardioplegia
group suggests inferior myocardial protection with the tepid
cardioplegia. Cold cardioplegia may provide better protection than tepid
cardioplegia when minicardioplegia is used.