[Changes in the contractile myocardium in acute rhythm disorders]

Experiments in rabbits were carried out to study the morphology of contractile myocardium in arrhythmias caused by electric stimulation of previously intact myocardium (1st group) and in those caused by inhalation of ammonia steam against the background of exogenous poisoning with barium chloride (2nd group). Morphological lesions of contractile myocardium consisting in granular an vacuolar dystrophy at 1--3 days of the experiment and focal myocytolysis at 7 days were demonstrated. In animals of the 2nd group, morphological lesions in the myocardium were more severe and by the 7th day of the experiment included both focal myocytolysis and contracture alterations. Changes in the blood vessels of the microcirculation bed were similar in both groups consisting of vascular spasm followed by paresis, plethora, diapedetic hemorrhages and early signs of thrombus formation. The latter was observed earlier in animals of the 2nd group. The observed morphological changes in contractile myocardium may be regarded as one of the forms on non-coronarogenic myocardiopathies.