The Annals of Thoracic Surgery, Vol 22, 424-428, Copyright © 1976 by The Society of Thoracic Surgeons
Effect of hypothermic anoxic cardioplegia on myocardial contractility
T Ino, A Wakabayashi, JE Guilmette Jr, RA Shinto and JE Connolly
A study was undertaken to ascertain the protective effect of topical
hypothermia on the anoxic heart. The presence or absence of myocardial
damage was judged by myocardial contractility. The papillary muscle of an
excised rabbit heart was detached from the mitral annulus and interposed
between a fixed point and a force/displacement transducer. The maximal net
developed tension (TNmax) of the papillary muscle with normothermic
coronary perfusion was used as an index of myocardial contractility. With
each temperature drop of 10 degrees C, the anoxia time that resulted in the
same recovery level of TNmax was prolonged by a factor of 2.8. A nomogram
was constructed correlating percent of myocardial recovery seen with
different degrees of myocardial hypothermia during various anoxic periods.
Optimum protection was noted at a myocardial temperature of 18 degrees C.