As changing the fuel climate farther, warmer summers, new research shows that the hearts of the elderly cannot maintain, exposing a tacit, increasing crisis at the intersection of aging and increasing temperatures.
Study: Cardiovascular challenges of aging in a warmer environment: a narrative review. Credit Picture: porporling/shutterstock.com
To a recent review in Newspaper of applied physiology; Researchers discussed the consequences of extreme heat on cardiovascular health of populations worldwide.
The authors examined how aging exacerbates the effects of thermal stress on the cardiovascular system, focusing on recent epidemiological findings, physiological mechanisms and environmental factors for cardiovascular risk in older adults.
Their conclusions emphasized the concerns that the aging of people exposed to heat conditions could face increased core temperatures, increasing the risk of cardiovascular disease and complications and therefore mortality.
Increase in heat and aging populations
Extreme environmental heat is the top cause of death associated with weather conditions worldwide and its impact is expected to rise as global temperatures continue to rise. Heat waves are becoming increasingly serious, exposing billions of people to prolonged high temperatures.
This report will extend dramatically with the increase in temperatures of 2 ° C. At the same time, the percentage of adults aged 65 years or older is increasing rapidly, it is projected to reach 1.6 billion (16.7% of the world population) by 2050.
As a result, this overlap of increasing heat and a rapid aging population creates a significant global health challenge, with greater adults more vulnerable to heat and death -related death, especially from cardiovascular causes.
Cardiovascular vulnerability due to extreme heat
Recent epidemiological studies steadily show that adults over 65 are facing the highest rate of hospital and deaths associated with heat, most of which are due to cardiovascular disease (CVD).
In New York alone, about 580 summer deaths are related to heat and 62% of them include pre -existing CVDs. As temperatures exceed the regional thresholds, heart failure risks, ischemic heart disease and stroke increase abruptly.
The increase in temperature 1 ° C is associated with a 2% increase in CVD mortality (cardiovascular disease) and an increase of 12% as the intensity of the thermal wave increases. In all the US, any excessive extreme heat in the month from 2008 to 2017 caused about 5,000 additional cardiovascular deaths in older adults.
Future forecasts estimate the 187% increase in such deaths by 2036 to 2065, stressing the urgent need for adaptive health measures. The authors emphasize that this data reflects mainly over the last 10 years of research, showing that extreme heat enhances cardiovascular risk even in areas that are not used to high temperatures.
Cardiovascular answers related to age
Exposure to heat requires a significant increase in heart supply to support skin blood flow and sweating for thermoregulation. However, older adults have a blunt cardiovascular response.
Studies show that younger adults can double heart benefit at about 11 l/min during passive heating, while older adults only reach about 7 l/min. This decrease comes from a limited volume of stroke and a reduced heart rate reserve, increasing heart stress.
Further research shows that even when elderly adults maintain the volume of the stroke, they do so by enhancing cardiac container and function closer to their maximum heart rate, thereby increasing the risk of myocardial stress. In those with coronary heart disease, this strain may exceed their heart reserve, occasionally leading to heat -caused ischemia.
Elderly adults also show a reduced ability to increase skin blood flow during heat exposure. This is largely due to the reduced availability of nitric oxide, oxidative stress and the weaker cholinergic and sympathetic activity of the sympathetic nerve. Such lesions limit vasodilation, reducing the body’s ability to effectively dissolve heat.
In addition, redistribution of blood from visceral organs such as the liver or kidneys on the skin is less effective with age. Elderly adults have about 30% less diversion of blood from internal to peripheral circulation during heating, increasing internal heat storage and cardiovascular stress.
The review also warns that most laboratory studies use water heating costumes, which can cause stronger cardiovascular responses than real reports. More ecologically valid studies in realistic environments are needed to improve these findings.
Definition of Environmental Risk Foams
Researchers have identified “critical environmental limits”, which are combinations of temperature and humidity, where cardiovascular stress is increasing abruptly, known as the appearance of cardiovascular displacement. For elderly adults who perform light daily activities, this occurs at about 35 ° C and 53% relative humidity in hot humid environments or 41 ° C and 24% in hot drying conditions.
Specifically, women, especially older women, have greater vulnerability, with a cardiovascular stem appearing in lower combinations of temperature-hydration than men. Based on unpublished observations from the PSU Heat project, this find suggests that older women can reach cardiovascular boundaries earlier under the same thermal conditions. Although cardiovascular mortality increases even at much lower ambient temperatures (about 22-25 ° C in certain cities), these thresholds mark the upper limits of safe exposure.
The authors further note that cardiovascular displacement, defined as a continuous increase in heart rate during prolonged heat exposure, is a timely warning of excessive cardiovascular stress before receiving thermal imbalance. Understanding these boundaries is vital to the design of premature warning systems and public health policies to prevent heat -related cardiovascular deaths in the growing elderly population of the world.
Conclusions
Heat -related mortality and morbidity disproportionately affect older adults, while people over 65 are recognized as the most vulnerable age with epidemiological studies. During thermal events, most deaths and hospitalizations between the elderly are due to CVDs and related complications, as aging affects the mechanisms by which the human body faces thermal stress.
The combination of more serious, long -term and frequent heat waves due to climate change and aging worldwide will affect billions of people.
The authors emphasize that continuing work is needed to identify accurate environmental conditions that cause excessive cardiovascular stress and to translate laboratory findings into practical real world prevention strategies. Further work to isolate environmental conditions that increase cardiovascular stress can help detect the how to reduce thermal pressure and consequently CVD caused by heat events.
