Summary
During open-heart surgery, myocardial biopsies were taken from 31 patients undergoing
aortic valve replacement on total cardiopulmonary bypass. The first needle biopsy
was taken before the induction of cardiac arrest (Kirsch cardioplegia), the second
at the end of global ischemia, and the third during the reperfusion period. The tissue
was investigated by electron microscopy using a semiquantitative scoring system for
changes in both myocytes and blood vessels. Mitochondrial volume and surface densitiy
were determined by morphometry. Reversible ischemic injury of moderate to severe degree
occurred in cardiac cells and in small blood vessels. On reperfusion, signs of damage
regressed earlier in myocardial than in vascular tissue. Morphometry revealed significant
mitochondrial swelling during the reperfusion phase, but this was not present after
ischemia alone. It is concluded that Kirsch cardioplegia as applied here, is unable
to protect the heart from ischemic cellular damage.
Key words
Cardiac arrest - Ischemia - Edema - Ultrastructure - Morphometry
