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Lorazepam reduces cardiac vagal modulation in normal subjects
L R Vogel1, P R Muskin, E D Collins
1Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Journal of Clinical Psychopharmacology
|December 1, 1996
Summary
Lorazepam (LZ) reduces heart period variability (HPV), a key indicator of sudden cardiac death risk, in healthy individuals. This study shows LZ significantly impacts autonomic nervous system function, affecting heart rate and vagal modulation.
Area of Science:
- Cardiology
- Pharmacology
- Autonomic Neuroscience
Background:
- Benzodiazepines are commonly used post-myocardial infarction.
- The impact of benzodiazepines on heart period variability (HPV), a predictor of sudden cardiac death, remains unclear.
- Previous studies on acute intravenous benzodiazepine doses have shown conflicting results regarding their effects on HPV.
Purpose of the Study:
- To investigate the effect of steady-state lorazepam (LZ) administration on heart period variability (HPV) in healthy human volunteers.
- To test the hypothesis that LZ reduces cardiac vagal modulation by potentiating GABA-Aergic inhibition of preganglionic vagal neurons.
Main Methods:
- A double-blind, randomized, placebo-controlled crossover study.
- Seven healthy subjects received either LZ or placebo for one week, followed by a one-week taper and crossover.
- Electrocardiogram recordings were used to measure HPV over 24 hours under normal physiologic activity.
Main Results:
- Lorazepam (LZ) significantly increased mean heart rate by 8%.
- LZ decreased multiple measures of heart period variability (HPV), including R-R interval standard deviation, successive difference analysis, and high-frequency power.
- These findings demonstrate significant vagolytic effects of LZ.
Conclusions:
- Steady-state lorazepam administration exerts vagolytic effects in healthy subjects.
- LZ's impact on HPV suggests a potential influence on autonomic balance relevant to cardiac event risk.
- Further research is needed to clarify the clinical implications of these findings in post-myocardial infarction patients.