Low cardiac output following open heart surgery often may be due to focal myocardial necrosis, say investigators at Henry Ford Hospital, Detroit.
Compromise of the smaller coronary vessels by microthrombi, microemboli and particulate foreign matter appears to be a major etiological factor.
Possible agents, said Azorides R. Morales, MD, associate in pathology, may include platelet aggregates, air emboli that escape into the coronary circulation during operation, the silicone antifoam used during extracorporeal circulation, and calcified emboli shed by the diseased heart valves.
Dr. Morales told the annual meeting of the American Society of Clinical Pathologists that necrotic lesions seen in patients with low output syndrome following heart surgery differ somewhat from those occurring in myocardial infarction following arteriosclerotic or thrombotic coronary artery occlusion.
The lesions occur in the absence of occlusion, or any significant degree of sclerosis, of the major coronary arteries. They are patchy and irregular in distribution,