The study showed that the stress on the heart is due to a strong increase in the systolic or so-called ‘top pressure’ when in the cold. For individuals with high variability in blood pressure in home measurements, the increase in blood pressure was about 30 mmHg, while for those with lower blood pressure variability, the increase was 23 mmHg. Correspondingly, the cardiac workload increased by 17% and 9% in cold conditions.
The result is significant for all individuals with very high blood pressure variability. “Significant variation in the blood pressure measured at home is likely to be due to a generally stronger reactivity of the sympathetic nervous system. The person reacts strongly to various environmental stress factors, in this case including cold temperature exposure,” says Docent Tiina Ikäheimo of the University of Oulu.
The effect was observed both in healthy individuals and individuals with high blood pressure, regardless of the blood pressure baseline. However, in cold conditions, blood pressure reaches the highest level in the case of individuals suffering from hypertension, who also show high home blood pressure variability.
A significant increase in blood pressure in cold conditions may increase the risk of harmful cardiovascular events in winter. In particular, those suffering from hypertension may be at a higher risk of adverse health effects.
Home blood pressure measurements provide valuable information about the individual’s reaction sensitivity to various stress factors such as cold temperatures. Regular blood pressure measurements can also be used to identify a person with elevated blood pressure. The study also provides additional information on mechanisms that can explain the higher winter morbidity rate and even mortality.
This extensive experimental study included 75 men aged between 55 and 65 from Oulu, Finland. From among them, 46 suffer from hypertension. The subjects were instructed to measure their blood pressure at home twice in the mornings and evenings for a week. Based on the measurements, they were divided into groups of low and high blood pressure variability. The subjects were invited to laboratory measurements at the Kastelli Research Centre, where they were exposed to a temperature of –10 C while wearing winter clothing for 15 minutes and their heart rate and blood pressure were measured.
The research was led by the Center for Environmental and Respiratory Health Research of the University of Oulu. The research results were published in the American Journal of Hypertension.
Docent Tiina Ikäheimo, Center for Environmental and Respiratory Health Research (CERH), University of Oulu, tel. +358 40 5422968, email: tiina.ikaheimo(a)oulu.fi
Hintsala HE, Kiviniemi AM, Antikainen R, Mäntysaari M, Jokelainen J, Hassi J, Tulppo MP, Herzig KH, Keinänen-Kiukaanniemi S, Rintamäki H, Jaakkola JJK, Ikäheimo TM. High Home Blood Pressure Variability Associates With Exaggerated Blood Pressure Response to Cold Stress. Am J Hypertens. 2019 May 9;32(6):538-546. doi: 10.1093/ajh/hpz011.
Last updated: 10.12.2019