Abstract 12231: T-Type and N-Type Calcium Channel Blockers Attenuate Cardiac Sympathetic Nervous Activity More Effectively Compared With L-Type Calcium Channel Blocker in Patients with Hypertension
Introduction: Sympathetic nervous activity is augmented with the calcium channel blocker (CCB) treatment as a result of decreased blood pressure despite the advent of long-acting CCBs. Dihydropyridine CCBs are divided into 3 different types depending on the deactivation rate of calcium channels. Accordingly, we hypothesized that there are some differences in the treatment effects on hemodynamics, cardiac autonomic nervous activity and plasma norepinephrine levels among amlodipine(L type), efonidipine(L+T type) and cilnidipine(L+N type).
Methods: We enrolled 14 hypertensive patients (7 male, 7 female, 70±6 years old) undergoing a monotherapy of amlodipine, efonidipine or cilnidipine to this prospective, randomized, cross-over study. At the end of each 6 month of treatment period, we repeated the evaluation of hemodynamics, heart rate variability and plasma norepinephrine levels. At each measurement time, patients underwent 30 minutes resting electrocardiographic recording in the morning after an overnight fasting. By using spectral analysis of heart rate variability, frequency-domain measures were calculated. The low frequency (LF: 0.04 to 0.15 Hz)/high frequency (HF: 0.15 to 0.40 Hz) power ratio was used as an index of sympathovagal balance, and HF/total power (TP) ratio was used as an index of vagal activity. Plasma norepinephrine levels were measured by radioimmunoassay.
Results: Measurements of hemodynamics, cardiac autonomic nervous activity and plasma norepinephrine concentrations are shown in Table. There was no statistically significant correlation between the LF/HF ratio and plasma norepinephrine levels (n=42, r=-0.122, p=n.s.).
Conclusion: Antihypertensive monotherapy with efonidipine or cilnidipine attenuates cardiac sympathetic nervous activity and augments cardiac parasympathetic activity compared with amlodipine monotherapy.
- Calcium channel blockers
- Heart rate/Heart rate variability
- Autonomic nervous system
- © 2011 by American Heart Association, Inc.