| Abstract |
Previous studies have suggested that patients with coronary artery disease have disturbances of the autonomic nervous system, which involve a reduction in parasympathetic tone. However, the precise role of autonomic nervous activity in the pathophysiology of myocardial ischemia is not clearly determined. Although the role of b-blockade in this field is well established, the effect of the drugs, which act in the parasympathetic branch, remains unknown. The aim of this study was to investigate: 1. The changes in the autonomic nervous system activity that involve in the pathogenesis of ischemic episodes. 2. The effect of transdermal scopolamine - a drug that in small doses increases tonic and reflex vagal outflow in healthy volunteers - in myocardial ischemia and its role as an adjunctive treatment for ischemic heart disease. Spectral analysis of heart rate variability was used to assess changes in the autonomic nervous system 10 min before, during and 10 min after 110 ischemic episodes in patients with stable coronary disease. In the most of diurnal episodes there was an increase in LF/HF ratio due to HF withdrawal that started before the onset of the ischemic episode. All nocturnal episodes also revealed an increase in the LF/HF ratio, which shows that the autonomic nervous system plays a significant role in triggering ischemic episodes. We also assessed whether transdermal scopolamine increases vagal tone in patients with severe coronary artery disease in comparison with healthy individuals and whether it might have an antiischemic effect. We found that patients with severe coronary artery disease have decreased time domain indexes of heart rate variability compared with healthy subjects. Transdermal scopolamine increased time domain measures and reduced the total number of ischemic episodes and their total duration. Transdermal scopolamine also increased treadmill exercise duration and the time to 1-min ST depression, while maximum ST depression was reduced. Finally, we investigated the ventricular ectopic activity before and after treatment with transdermal scopolamine in patients with stable coronary disease. We also assessed the relationship between the ventricular arrhythmiogenesis and myocardial ischemia. We did not find any difference in ventricular ectopic activity in the patients under scopolamine treatment. However, there was a significant reduction in transient ischemia in those patients that resulted in a reduction of ventricular ectopic activity related with ischemic episodes. In conclusion, the transdermal administration of scopolamine causes an increase in the indices of heart rate variability in patients with severe but uncomplicated coronary disease. Scopolamine also reduced the incidence and duration of ischemic episodes and improved the exercise test parameters. However the long-term results of its administration remains to be evaluated.
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Επίδραση της παρασυμπαθομιμητικής δράσης των χαμηλών δόσεων σκοπολαμίνης στον τόνο του αυτόνομου νευρικού συστήματος και στη θεραπεία της ισχαιμικής καρδιακής νόσου
