[Functional characteristics of the cardiovascular system of old people--inhabitants of the north].

The electrocardiographic investigation of healthy old people from three ethnic groups of natives of the Komi Republic at the age of 80+ years revealed increase of QRS-complex, enlargement P-Q and Q-T intervals duration, decrease of amplitude of T-wave. This testifies to age-associated lowering of the depolarization processes in myocardium, increase of atrio-ventricular conductivity and compensative extension of repolarization period. We determined the predominance of the left direction of ORS axis in old people. The increase of amplitude of mode of R-R intervals (AMo 50-90%), low range of variation of cardio intervals characterize heart rate stability in 60% of subject, indicate the limitation of sinus node lability and decrease of cortex component in regulation of cardiac rhythm. These processes in old people are adaptive ones to reduce redundant stress of heart capacity in extreme conditions. Normotensive people amounted more than 50% of investigated Northern Komi (SBP 125 +/- 13, DBP 72 +/- 8 mmHg). In groups of Russian women and Southern Komi the prevalence of hypertension revealed itself and it reached in average 170/97-174/87 mmHg.