Cardiac rhythm in cats during physiological sleep in experimental myocardial infarction and beta-adrenergic receptor blockade.

The authors investigated parameters of the sinus rhythm and of the structure of physiological sleep in 11 cats after ligation of the interventricular artery. ECG of the cerebral cortex, electromyogram, electrooculogram, ECG and respiration were registered, both in the acute period of infarction (4th-10th day of the experiment) and in the subacute and late period (3-12 months). In the acute and subacute period, an abrupt decrease was found in the sinus rhythm variability during the waking-sleep cycle.