Potassium, Magnesium, and Neostigmine for Controlled Cardioplegia Studies on the Dog Using Extracorporeal Circulation and Hypothermia

A description of our method of achieving cardioplegia for deliberate open heart surgery has been reported. In our first experiments, 1 where the cat heart was perfused by the Langendorff technique, it was found that a combination of potassium citrate, magnesium sulfate, and neostigmine was the most efficient method for stopping the heart. A second series 2 of acute experiments on the intact hypothermic dog confirmed these findings. This is the third report of this series, and it will relate our observations on the dog using extracorporeal circulation, hypothermia, and prolonged induced cardiac standstill with potassium citrate 0.81%, magnesium sulfate 2.41%, and neostigmine methylsulfate 0.001%. In these experiments we did not attempt to compare this solution with potastium citrate alone, acetylcholine, or other antifibrillatory and cardioplegic solutions. Methods Healthy dogs of both sexes were used. Preoperative preparation in some of the dogs was with neomycin and chlortetracycline (Aureomycin) given 24