Functional capacity of the cardiovascular system of elderly people as estimated by heart rate variability

With the aid of mathematical and spectral analysis of the heart rate (HR) wave structure in a dynamic interval tachogram (TG) in elderly subjects, it has been shown that a stable sinus rhythm is typical of the majority of the indigenous population of the rural areas of the North aged 78–97 years and migrants living in the city of Vorkuta aged 60–88 years. The total RR-interval spectrum power (800 ± 98 ms²) in the TGs of the native population is shifted to the very low frequency band (VLF, 52%), which indicates predomination of the humoral-metabolic HR regulation level. The reaction to orthostatic load in elderly subjects is characterized by a significant increase in the total spectrum power, which indicates changes in the autonomic balance of regulation of the wave structure of the HR variability. A low total spectrum power (609 ± 104 ms²) with a predominance of low frequency (LF) waves in the TGs of the migrants at rest reflects the activity of the sympathetic component of HR regulation. The reduction of the parasympathetic regulation and the growth of the sympathetic activity during an active orthostatic test in the migrants is a predictor of cardiovascular diseases. In individual TGs of recipients with HR disorders, the orthostatic test (the redistribution of blood flow in the main vessels) results in a decrease in the number of extrasystoles due to the specific features of the baroreflex regulation mechanisms of the cardiovascular system. The HR variability has been shown to be an indicator of the functional capacity of the cardiovascular system in elderly subjects.