RESUMO
OBJECTIVE: To study the effect of antihypertensive medications on autonomic nervous system in patients with hypertension and sleep apnea syndrome using frequency domain measures of heart rate and blood pressure variabilities. METHODS: The beta-receptor blocking agent atenolol (50 mg), the calcium antagonist isradipine SRO (2.5 mg), the diuretic hydrochlorothiazide (25 mg) and the ACE inhibitor spirapril (6 mg) once daily were given in a double-blind crossover schedule for 8 weeks. Cardiovascular autonomic control was assessed using frequency domain measures of heart rate variability during the spontaneous and controlled breathing tests. During orthostatic maneuver and cold pressor test the blood pressure variability analysis also was performed. RESULTS: In general, the responses of heart rate and blood pressure variabilities were abnormal in the patients with arterial hypertension and sleep apnea syndrome compared to reference data. Of the four drugs, only atenolol effected heart rate and blood pressure variabilities as it shifted the autonomic regulation to the vagal direction. Other antihypertensive drugs did not change any parameter of heart rate or blood pressure variabilities. CONCLUSION: The short-term treatment with atenolol in patients with arterial hypertension and sleep apnea syndrome is associated with normalization of autonomic nervous control judged by heart rate and blood pressure variability. Thus, beta-receptor blockade may have adjunctive beneficial effects beyond blood pressure reduction in these patients. However, the long-term effects of blood pressure reduction on autonomic nervous control remain to be studied.
