H2-blocker modulates heart rate variability.

The use of H2-blockers in the treatment of patients with peptic ulcer has become popular. However, this treatment has adverse cardiovascular effects. The aim of this study was to investigate proarrhythmic rhythm and autonomic nervous activity by analyzing heart rate variability in patients treated with omeprazole, ranitidine, and plaunotol. Nineteen patients (mean age 67.5 +/- 2.7 years) with active gastric ulcer were treated with omeprazole (20 mg/day) for 8 weeks, then ranitidine (300 mg/day) for the next 4 months, and finally plaunotol (240 mg/day). At each stage of the treatment, Holter electrocardiography was performed, and heart rate variability and arrhythmias analyzed. Heart rate variability yielded power in the low- (0.04-0.15 Hz) and high-frequency components (0.15-0.4 Hz). Although both ranitidine and omeprazole induced little change in cardiac rhythm, the high-frequency power was higher (10.3 +/- 0.8 vs 8.6 +/- 0.6 ms, P < 0.05) and the ratio of low-to-high frequency power was lower (1.41 +/-0.10 vs 1.59 +/- 0.09. P < 0.05) during ranitidine than during plaunotol treatment. Cosinor analysis of heart rate variability revealed a decreased amplitude of low-frequency power during omeprazole compared with during ranitidine and plaunotol treatment. Ranitidine modulated high-frequency power which may be related to the adverse cardiovascular effects of H2-blocker.