Intermittent antegrade hyperkalaemic warm blood cardioplegia supplemented with magnesium prevents myocardial substrate derangement in patients undergoing coronary artery bypass surgery.
OBJECTIVE
The influence of the addition of magnesium on myocardial protection with intermittent antegrade warm blood hyperkalaemic cardioplegia in patients undergoing coronary artery surgery was investigated and compared with intermittent antegrade warm blood hyperkalaemic cardioplegia only.


METHODS
Twenty-three patients undergoing primary elective coronary revascularization were randomized to one of two different techniques of myocardial protection. In the first group, myocardial protection was induced using intermittent antegrade warm blood hyperkalaemic cardioplegia. In the second group, the same technique was used except that magnesium was added to the cardioplegia. Intracellular substrates (ATP, lactate and amino acids) were measured in left ventricular biopsies collected 5 min after institution of cardiopulmonary bypass, after 30 min of ischaemic arrest and 20 min after reperfusion.


RESULTS
There were no significant changes in the intracellular concentration of ATP or free amino acid pool in biopsies taken at the end of the period of myocardial ischaemia. However, the addition of magnesium prevented the significant increase in the intracellular concentration of lactate seen with intermittent antegrade warm blood hyperkalaemic cardioplegia. Upon reperfusion there was a significant fall in ATP and amino acid concentration when the technique of intermittent antegrade warm blood hyperkalaemic cardioplegia was used but not when magnesium was added to the cardioplegia.


CONCLUSIONS
This work shows that intermittent antegrade warm blood hyperkalaemic cardioplegia supplemented with magnesium prevents substrate derangement early after reperfusion.
Caputo
M
M
Bristol Heart Institute, University of Bristol, Bristol Royal Infirmary, UK.
Bryan
A J
AJ
Calafiore
A M
AM
Suleiman
M S
MS
Angelini
G D
GD
D000255:Adenosine Triphosphate / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D001706:Biopsy; D001769:Blood; D002121:Calcium Channel Blockers; D002314:Cardioplegic Solutions / Q000737:chemistry*; D001026:Coronary Artery Bypass / Q000379:methods*; D005260:Female; D006324:Heart Arrest, Induced / Q000379:methods*; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008278:Magnesium Sulfate; D008297:Male; D008875:Middle Aged; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D013997:Time Factors
D000596:Amino Acids; D002121:Calcium Channel Blockers; D002314:Cardioplegic Solutions; D019344:Lactic Acid; D008278:Magnesium Sulfate; D000255:Adenosine Triphosphate