Heart rhythm disturbances during the acute period of massive pulmonary embolism.

We studied the type, incidence, and dynamics of arrhythmia during the acute phase of massive pulmonary embolism complicated or uncomplicated by cardiac insufficiency. Complicated and uncomplicated massive pulmonary embolisms were accompanied by the appearance of individual and allorhythmic ventricular extrasystoles, respectively. The rise of right ventricular pressure to 70 mm Hg was critical for the development of allorhythmia. Allorhythmia started 3-268 sec after attaining critical ventricular pressure. Heart rhythm spontaneously recovered in 100 and 78% animals with uncomplicated and complicated massive pulmonary embolism, respectively. The duration of paroxysmal allorhythmia varied from 15 sec to 15 min. Electrophysiological processes in the myocardium were normalized with progression of uncomplicated massive pulmonary embolism: the incidence of single and, in particular, allorhythmic extrasystoles decreased, and electrocardiographic parameters returned to normal.