Heart Disease

Cardiovascular disease or heart disease are a class of diseases that involve the heart or blood vessels (arteries and veins). While the term technically refers to any disease that affects the cardiovascular system (as used in MeSH C14), it is usually used to refer to those related to atherosclerosis (arterial disease). These conditions usually have similar causes, mechanisms, and treatments.

Cardiovascular Disease

Micrograph of a heart with fibrosis (yellow) and amyloidosis (brown). Movat’s stain

Cardiovascular diseases remain the biggest cause of deaths worldwide, though over the last two decades, cardiovascular mortality rates have declined in many high-income countries but have increased at an astonishingly fast rate in low- and middle-income countries. The percentage of premature deaths from cardiovascular disease range from 4% in high-income countries to 42% in low-income countries. More than 17 million people died from cardiovascular diseases in 2008. Each year, heart disease kills more Americans than cancer. In recent years, cardiovascular risk in women has been increasing and has killed more women than breast cancer. (PDAY) showed vascular injury accumulates from adolescence, making primary prevention efforts necessary from childhood.

By the time that heart problems are detected, the underlying cause (atherosclerosis) is usually quite advanced, having progressed for decades. There is therefore increased emphasis on preventing atherosclerosis by modifying risk factors, such as healthy eating, exercise, and avoidance of smoking.

Risk factors

[] Age

Age is an important risk factor in developing cardiovascular diseases. It is estimated that 82 percent of people who die of coronary heart disease are 65 and older. At the same time, the risk of stroke doubles every decade after age 55.

Multiple explanations have been proposed to explain why age increases the risk of cardiovascular diseases. One of them is related to serum cholesterol level.In most populations, the serum total cholesterol level increases as age increases. In men, this increase levels off around age 45 to 50 years. In women, the increase continues sharply until age 60 to 65 years.

Aging is also associated with changes in the mechanical and structural properties of the vascular wall, which leads to the loss of arterial elasticity and reduced arterial compliance and may subsequently lead to coronary artery disease.

[] Gender

Men are at greater risk of heart disease than pre-menopausal women. However, once past menopause, a woman’s risk is similar to a man’s.

Among middle-aged people, coronary heart disease is 2 to 5 times more common in men than in women. In a study done by the World Health Organization, gender contributes to approximately 40% of the variation in the sex ratios of coronary heart disease mortality.Another study reports similar results that gender difference explains nearly half of the risk associated with cardiovascular diseases One of the proposed explanations for the gender difference in cardiovascular disease is hormonal difference. Among women, estrogen is the predominant sex hormone. Estrogen may have protective effects through glucose metabolism and hemostatic system, and it may have a direct effect on improving endothelial cell function. The production of estrogen decreases after menopause, and may change the female lipid metabolism toward a more atherogenic form by decreasing the HDL cholesterol level and by increasing LDL and total cholesterol levels. Women who have experienced early menopause, either naturally or because they have had a hysterectomy, are twice as likely to develop heart disease as women of the same age group who have not yet gone through menopause.

Among men and women, there are differences in body weight, height, body fat distribution, heart rate, stroke volume, and arterial compliance. In the very elderly, age related large artery pulsatility and stiffness is more pronounced in women.This may be caused by the smaller body size and arterial dimensions independent of menopause.

[] Air pollution

Particulate matter have been studied for their short- and long-term exposure effects on cardiovascular disease. Currently, PM2.5 is the major focus, in which gradients are used to determine CVD risk. For every 10 μg/m3 of PM2.5 long-term exposure, there was an estimated 8-18% CVD mortality risk. Women had a higher relative risk (RR) (1.42) for PM2.5 induced coronary artery disease than men (0.90) did. Overall, long-term PM exposure increased rate of atherosclerosis and inflammation. In regards to short-term exposure (2 hrs), every 25 μg/m3 of PM2.5 resulted in a 48% increase of CVD mortality risk. Additionally, after only 5 days of exposure, a rise in systolic (2.8 mmHg) and diastolic (2.7 mmHg) blood pressure occurred for every 10.5 μg/m3 of PM2.5. Other research has implicated PM2.5 in irregular heart rhythm, reduced heart rate variability (decreased vagal tone), and most notably heart failure. PM2.5 is also linked to carotid artery thickening and increased risk of acute myocardial infarction.

Source:

Wikipedia contributors. Cardiovascular disease. Wikipedia, The Free Encyclopedia. January 12, 2012, 17:03 UTC. Available at: http://en.wikipedia.org/w/index.php?title=Cardiovascular_disease&oldid=470993619. Accessed January 13, 2012.