Whole-body cold exposure increased cardiac baroreflex sensitivity similarly in both groups, but the increase in low frequency blood pressure variability was significantly blunted in untreated hypertensive men (0 mmHg2) compared to normotensive controls (8 mmHg2).
Observational (n=41)
No
Does untreated hypertension alter the response of cardiac baroreflex sensitivity and blood pressure variability to moderate cold exposure in men aged 55-65?
Untreated hypertension does not impair the protective increase in cardiac baroreflex sensitivity during moderate cold exposure, though it may blunt peripheral sympathetic responsiveness.
Absolute Event Rate: 0% vs 8%
p-value: p=<0.05
Exposure to cold increases blood pressure and may contribute to higher wintertime cardiovascular morbidity and mortality in hypertensive people, but the mechanisms are not well-established. While hypertension does not alter responses of vagally-mediated heart rate variability to cold, it is not known how hypertension modifies baroreflex sensitivity (BRS) and blood pressure variability during cold exposure. Our study assessed this among untreated hypertensive men during short-term exposure comparable to habitual winter time circumstances in subarctic areas. We conducted a population-based recruitment of 24 untreated hypertensive and 17 men without hypertension (age 55-65 years) who underwent a whole-body cold exposure (-10°C, wind 3 m/s, winter clothes, 15 min, standing). Electrocardiogram and continuous blood pressure were measured to compute spectral powers of systolic blood pressure and heart rate variability at low (0.04-0.15 Hz) and high frequency (0.15-0.4 Hz) and spontaneous BRS at low frequency (LF). Comparable increases in BRS were detected in hypertensive men, from 2.6 (2.0, 4.2) to 3.8 (2.5, 5.1) ms/mmHg median (interquartile range), and in control group, from 4.3 (2.7, 5.0) to 4.4 (3.1, 7.1) ms/mmHg. Instead, larger increase (p < 0.05) in LF blood pressure variability was observed in control group; response as median (interquartile range): 8 (2, 14) mmHg(2), compared with hypertensive group 0 (-13, 20) mmHg(2). Untreated hypertension does not disturb cardiovascular protective mechanisms during moderate cold exposure commonly occurring in everyday life. Blunted response of the estimate of peripheral sympathetic modulation may indicate higher tonic sympathetic activity and decreased sympathetic responsiveness to cold in hypertension.
Hintsala et al. (Thu,) conducted a observational in Untreated hypertension (n=41). Whole-body cold exposure vs. Normotensive control group was evaluated on Increase in low frequency (LF) blood pressure variability (p=<0.05). Whole-body cold exposure increased cardiac baroreflex sensitivity similarly in both groups, but the increase in low frequency blood pressure variability was significantly blunted in untreated hypertensive men (0 mmHg2) compared to normotensive controls (8 mmHg2).