Aging, cardiovascular changes that occur with
The most significant age-related changes in cardiovascular function occur at birth in both sexes and with MENOPAUSE in women. Though changes in METABOLISM occur with aging that affect all body systems, researchers now believe cardiovascular health does not inherently decline simply as a function of aging. DIABETES, OBESITY, lack of physical exercise, and cigarette smoking are the leading causes of acquired CARDIOVASCULAR DISEASE (CVD) among adults. The effects of these factors are cumulative; they are more likely to result in disease the longer they exist and the more of them are present. Accordingly, the risk for acquired cardiovascular disease increases with age because as people get older they tend to develop health conditions that set the stage for cardiovascular deterioration. Most researchers believe these risks are mutable (changeable) through lifestyle.
Cardiovascular Changes at Birth
The cardiovascular system is among the first body systems to develop in the EMBRYO, with the rudimentary HEART beginning to beat at three weeks gestational age. The heart fully forms, and a rudimentary circulatory network develops and functions, by eight weeks gestational age. Before birth, the FETUS draws its oxygen supply from its mother’s BLOOD supply, in an exchange that takes place across a membrane in the PLACENTA (fetal and maternal blood supplies do not mix). Accordingly, the fetal LUNGS do not function. Blood flows to and from the fetus through the umbilical arteries and veins (UMBILICAL CORD).
In the adult heart the right ventricle pumps blood through the PULMONARY ARTERIES to the LUNGS for OXYGENATION. The blood returns to the heart via the PULMONARY VEINS. Because the fetal lungs are nonfunctional, the fetal circulatory system bypasses the lungs. An opening (shunt) between the atria, the foramen ovale, allows blood to flow from the right atrium to the left atrium, which pumps it to the left ventricle. A small amount of blood goes from the right atrium to the right ventricle, which pumps it into the pulmonary ARTERY. A shunt between the aorta and the pulmonary artery, the ductus arteriosus, directs the blood into the aorta where it mixes with the blood the left ventricle pumps into the AORTA. With the first breath following birth the lungs inflate and the changes in pressure initiate a series of biochemical actions that cause these shunts to close, establishing blood circulation through the lungs. Within a few days of birth the ductus arteriosus becomes the ligamentum arteriosum, a strip of connective tissue that stabilizes the aorta and the pulmonary artery. The umbilical veins retreat to form the round ligament supporting the LIVER and the umbilical arteries to form ligaments that support the abdominal muscles.
Cardiovascular Changes at Menopause
Estrogen, the HORMONE responsible for female FERTILITY, is essential for lipid metabolism. The high estrogen levels that mark fertility seem to exert a protective action on a woman’s cardiovascular system, lowering the likelihood for HYPERLIPIDEMIA and related health conditions such as ATHEROSCLEROSIS and CORONARY ARTERY DISEASE (CAD). During the 35 to 40 years of her fertility, a woman’s risk for cardiovascular disease is a third to half that of a man of comparable age and health status. At MENOPAUSE estrogen levels drop significantly and a woman’s risk for cardiovascular disease takes a significant jump. Some studies suggest that during the first five years following menopause, a woman’s risk for HEART ATTACK is greater than that of a man who is of comparable age and health status.
Hormone replacement therapy (HRT) to restore estrogen levels after menopause became a standard medical approach in the 1950s. In the 1990s numerous studies revealed significant increases in the risks for BREAST CANCER and uterine CANCER associated with HRT as well as failed to find supportive evidence that HRT improved cardiovascular health in women after menopause, and health experts withdrew recommendations for its routine use. Current recommendations suggest women, like men, make nutritious eating choices, get daily physical exercise, maintain healthy weight, and not smoke as the key preventive measures to lower their risk for cardiovascular disease in midlife and beyond.
Lifestyle Choices to Maintain Cardiovascular Health
Current research strongly supports the role of lifestyle choices in maintaining cardiovascular health, even to the extent that many researchers believe appropriate choices beginning in early childhood could prevent as much as 90 percent of acquired cardiovascular disease. Healthy adults who are in their 70s and 80s who do not have any form of cardiovascular disease or other chronic health conditions do not have significant changes in cardiovascular function. Weight management, not smoking, nutritious food choices, and daily physical exercise are the cornerstones of lifestyle measures to preserve cardiovascular health. Many researchers believe the healthy cardiovascular system has the capacity to function efficiently well into the eighth decade of life and beyond.
See also CARDIOVASCULAR DISEASE PREVENTION; CONGENITAL HEART DISEASE; ESTROGENS; LIFESTYLE AND CARDIOVASCULAR HEALTH; LIGAMENT; MUSCLE; PREGNANCY; SMOKING CESSATION; WEIGHT LOSS AND WEIGHT MANAGEMENT.
