[Effect of beta-blockers on the cardiac rhythm variability in patients with hypertension]

As many as 29 patients with arterial hypertension were examined. All patients were instituted a 3-week antihypertensive therapy with metoprolol. Against the background of intake of metoprolol, there occurs a rise in indices for variability of the heart's rhythm. Augmentation of total power of the spectrum due to metoprolol occurs largely because of enhancement of the parasympathetic activity which can be regarded as a positive effect on the sympathicopara-sympathetical control. In apparent enhancement of the parasympathetic nervous system against the background of ingestion of metoprolol the activity of the sympathetic component is not inhibited, the drug leading to redistribution of influences toward that portion of the autonomic nervous system which had been more inhibited before the intake of the drug.