부산대학교 도서관

Objective: Antihypertensive agents of different classes may have profound effects on heart rate variability (HRV). HRV changes in patients with essential hypertension were evaluated after pharmacological treatment by time domain (TD) analysis on 24-hour electrocardiographic (ECG) recordings. Design and Patients: In this randomised block single-blind trial, 45 patients with essential hypertension were randomly assigned to either atenolol, a cardioselective β-blocker, carvedilol, a β-blocker with vasodilator properties, or lacidipine, a long-acting dihydropyridine calcium antagonist, and underwent simultaneous 24-hour ECG and ambulatory blood pressure monitoring before and after 8 weeks' treatment. TD measures were calculated. Results: During treatment with atenolol and carvedilol, the 24-hour average normal RR [mean normal to normal intervals (NN)] was significantly increased (p < 0.0001 and p < 0.0002, respectively). Measures of tonic vagal activity were increased significantly only with atenolol: increase of 64.3% for the percentage of differences >50msec between adjacent NN intervals and increase of 45.2% for root mean square successive differences. By contrast, standard deviations (SD) of all NN over a 24-hour period and SD of means of 5-minute blocks of NN related to total and diurnal HRV were significantly increased by lacidipine (13.4 and 18.9%, respectively) and decreased by carvedilol (-12.0% and -22.0%, respectively) but not significantly modified by atenolol. Modifications in TD parameters were unrelated to the degree of 24-hour blood pressure reduction. Conclusions: HRV, assessed by TD, is modified differently according to the specific type of antihypertensive monotherapy used. These modifications could have prognostic importance. TD measures of HRV may be a practical and powerful instrument for the evaluation of the effect of antihypertensive drugs. [ABSTRACT FROM AUTHOR]