The Annals of Thoracic Surgery, Vol 39, 218-222, Copyright © 1985 by The Society of Thoracic Surgeons
Interactions between pharmacological cardioplegia and hypothermia for intraoperative myocardial protection
M Chiavarelli, R Chiavarelli, A Carpi and B Marino
Cold cardioplegia is currently the method of choice for providing
myocardial protection during open-heart surgical procedures. Two components
of protection, perfusion cooling and pharmacological cardiac arrest, were
investigated in the guinea pig heart-lung model. The effects of two
cardioplegic solutions, the University of Alabama Hospital solution and the
St. Thomas' Hospital solution, and a control perfusate were compared. The
results confirmed the efficacy of hypothermia as a protective agent and the
additional protection afforded by pharmacological cardioplegia. Infusion
temperature critically influenced the cardioprotective action of the
Alabama solution: Striking protection was afforded only under hypothermic
conditions, whereas myocardial damage was exacerbated by the infusion at 37
degrees C. The St. Thomas' Hospital solution provided substantial
protection independent of infusion temperature. Thus, the safety margin of
the Alabama solution was narrower than that of the St. Thomas' solution. It
is suggested that the difference between the two cardioplegic solutions
partially depends on their coronary vasoactivity, since the administration
of the Alabama solution at 37 degrees C increased coronary perfusion
pressure. It would seem worthwhile to use a temperature-independent
cardioplegic solution devoid of coronary vasoconstricting action.
