Avtor/Urednik		Vrtovec, Bojan
Naslov		Kronotropni in nekronotropni vplivi na variabilnost intervala QT
Tip		monografija
Kraj izdaje		Ljubljana
Založnik		Medicinska fakulteta
Leto izdaje		2000
Obseg		str. 44
Jezik		slo
Abstrakt		Background. Beat-to-beat QT interval variability changes represent a sensitive marker reflecting disturbances in ventricular repolarization. Ventricular repolarization is affected mainly by changes in heart rate (chronotropic control). The degree of chronotropic control is modified by variety of non-chronotropic stimuli, that change the structure, distribution or electrophysiologic properties of ventricular myocardium. Even though basic studies have shown, that changes in serum concentration of 17beta-estradiol result in significant alterations of ventricular repolarization dynamics, no clinical studies have investigated the relevance of these findings. While the results of population-based studies have suggested a significant prolongation of rate-adjusted QT interval duration with increasing age, the data regarding possible age-related changes in beat-to-beat QT interval variability are lacking. The hypothesis our study was that 17beta-estradiol and aging display a significant impact on ventricular repolarization dynamics. We tested the proposed hypothesis by analysing the interplay of chronotropic and nonchronotropic modulation of ventricular repolarization. Methods. The degree of repolarization changes was evaluated using a new method based on beat-to-beat QT interval variability quantitation. As a reference technique, standard QT duration measurements corrected by Bazett formula, were used. To investigate a possible influence of serum 17beta-estradiol levels on QT interval variability, we recruited 30 healthy post-menopausal women and treated them with 2 mg 17beta-estradiol daily for 10 weeks. Serum 17beta-estradiol concentration and beat-to-beat QT interval variability were determined at baseline and after the 10-week treatment period. A possible impact of aging on ventricular repolarization dynamics was based on QT interval variability measurements in 60 healthy male subjects, aged 20-65 years. Results. (Abstract truncated at 2000 characters)
Deskriptorji		ELECTROCARDIOGRAPHY HEART VENTRICLE ACTION POTENTIALS ESTROGEN REPLACEMENT THERAPY AGING POSTMENOPAUSE AGE FACTORS HEART RATE ESTRADIOL