The Annals of Thoracic Surgery, Vol 31, 339-346, Copyright © 1981 by The Society of Thoracic Surgeons
St. Thomas cardioplegia versus topical cooling: ultrastructural and biochemical studies in humans
W Flameng, M Borgers, W Daenen, F Thone, WA Coumans, GJ Van der Vusse and G Stalpaert
Transmural left ventricular biopsies were studied from 28 patients
undergoing cardiopulmonary bypass with anoxic cardiac arrest. The
myocardium was protected by topical cooling (20 degrees C) (Group 1, 15
patients) or by cardioplegia with St. Thomas' solution (Group 2, 13
patients). Biopsies were taken at the start of bypass and 3 to 5 minutes
after unclamping of the aorta. Mean cross-clamp time was not significantly
different between the groups (50 minutes for Group 1 and 53 minutes for
Group 2; p greater than 0.05). The ultrastructural changes induced by
ischemia and subsequent reperfusion were almost exclusively related to the
mitochondria. The degree of mitochondrial damage was evaluated by a
semiquantitative analysis based on mitochondrial fine structure. The
frequency of severe postischemic mitochondrial damage was significantly
higher in Group 1 (20.1% versus 2.7% in Group 2; p less than 0.05).
Biochemical analysis of the biopsies indicates that the myocardial
concentration of creatine phosphate decreases by about 50% after topical
cooling (p less than 0.05). With St. Thomas cardioplegia, no significant
change in the tissue level of this high-energy phosphate takes place. The
results show evidence of the superiority of the St. Thomas cardioplegia to
topical cooling alone.