Sensitive markers of the repolarization alterations in systemic hypertension

Introduction: The early phase of essential hypertension has been associated with changes in cardiovascular regulation caused by imbalance in some parts of autonomic nervous system. Autonomic effect of various stimuli on haemodynamic variables is usually tested by changes in blood pressure (BP) and/ or heart rate (HR). It is known that increased sympathetic drive of ventricles can interfere with repolarization process. The aim: This study was focused on reactive changes of maximal spatial T vector (sTmax) and R-R intervals, in relation to BP changes in 79 boys and men, averaged age 17‐2 yrs. 36 from them where adolescents with elevated BP (high normal or hypertension I†according to WHO/ISH1999) (EBP), 19 normotensives (NBP), and 24 normotensive sportsmen. R-R intervals and maximal spatial T vector were recorded by a†PC (Cardiag METE, Prague) with Frank lead system while sitting in mid-respiratory position, during mental arithmetic (MA) and during passive head-up tilting to 60∞. BP was measured simultaneously by a cuff sphygmomanometer, using phases 1 and 5 of Korotkoff sounds. Results: MA resulted in significant BP increase in all subgroups, however the reactive changes of systolic BP as well as magnitude of R-R shortening, and sTmax decline were about two times higher in sportsmen. Head-up tilting evoked in all subgroups a†significant increase of diastolic BP that was again higher in sportsmen vs. EBP and NBP. R-R interval became significantly (p<0.02) and more often shortened in sportsmen than in EBP and NBP. Relatively more evident decline of sTmax (more than 20 %) in EBP was the highest change from all observed parameters to both tested stimuli. Conclusion: Our results indicate that for analysis of the effect of stimuli, which modulate balance in autonomic nervous system, it is helpful to pay attention also to the parameters of repolarization process that may represent a sensitive indicator of sympathetic tonization in myocardial ventricles. (Tab. 4, Fig. 2, Ref. 27.)