title: Cardioplegia versus topical cooling for cardiac protection during open-heart surgery. An electron microscopic and histochemical study of right atrial biopsies.
abstract: The effectiveness of topical cooling and cold cardioplegia for cardiac protection in the course of open-heart surgery was studied by electron microscopy and fluorescence microscopy of right atrial biopsies. In 20 patients with topical cooling, no changes or minimal changes were observed in 15 cases, more pronounced changes in 3 cases, and severe destruction in 2 cases. In the group of 20 patients with cold cardioplegia the range of the changes was significantly narrower: no specimen remained completely intact; on the other hand, very severe destruction was not observed. Fluorescence microscopy revealed that the neural noradrenaline stores were relatively resistant to ischaemia. Electron microscopy showed certain failure of the protective procedure, resulting in injury of myocardial cells and neural elements. Even "spot-like" destruction noted in the nerve terminals may interfere with the peripheral neuro-neuronal interaction, resulting in nonhomogenous spread of the excitation wave front and electrical instability of the heart. Therefore cardiac nerve damage should also be taken into consideration when evaluating the effectiveness of different methods for cardiac protection.
mesh_terms: D001021:Aortic Valve / Q000601:surgery* / Q000648:ultrastructure; D001706:Biopsy; D006324:Heart Arrest, Induced; D006801:Humans; D007036:Hypothermia, Induced; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D011183:Postoperative Complications / Q000473:pathology*