Coronary Heart Disease: Causes
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|How Does CHD Occur?
Coronary heart disease (CHD) is caused by a narrowing of the coronary arteries. These are the vital arteries which supply blood and oxygen to the heart muscles. This narrowing process is known as atherosclerosis (a type of arteriosclerosis, although the two terms are used interchangeably). Atherosclerosis is a condition where fatty materials – cholesterol (atheroma) and fibrosis (sclerosis) - collect along the walls of the arteries. This material gradually thickens and hardens over time forming calcium deposits called plaques. It may also stimulate the cells of the artery walls to produce other substances which also stick. Eventually the build up is so great that blood flow becomes restricted causing angina attacks and if it becomes completely blocked, a heart attack. Atherosclerosis usually affects the larger and medium sized arteries.
A blockage can also happen suddenly too – this occurs if a piece of the plaque breaks off (ruptures) causing blood cells (platelets) to form at the rupture point. The clot can cause a blockage at this point. Or sometimes the plaque and platelets can be carried along the artery towards a vessel with a smaller diameter where it suddenly stops blood flow. If the clot travels towards the heart it causes a heart attack heart attacks. It if travels to the lungs it causes a pulmonary embolism and if it moves to the brain it can cause a stroke (see stroke in women). If blood supply to the legs or arms is stopped it can cause movement problems and eventually gangrene.
CHD is a complex condition which is usually caused by high cholesterol but is exacerbated by other factors including diabetes, smoking, obesity and high blood pressure.
Cholesterol is a waxy substance, produced by the liver, and is necessary for normal body functions. It is present in the cell membranes and walls of the skin, brain, nerves, heart, muscles and every other part of the body. Cholesterol is used by the body to create hormones, vitamin D and bile acids used to digest fat. However, the body only requires a small amount of cholesterol for these functions. If a person eats too many foods containing cholesterol, this can lead to an excess in the blood stream which is dumped along the lining of the arteries. It then combines with other substances to form a calcified plaque, causing narrowing and blockages of the arteries. Cholesterol is carried in the bloodstream by molecules called lipoproteins. There are few different types of lipoproteins but the main two are: high-density lipoproteins (HDL) and low-density lipoproteins (LDL). HDL is known as the 'good' cholesterol as it helps take away access cholesterol from the cells and delivers it back to the liver for breaking down and expelling from the body. LDL is known as the 'bad' cholesterol as it takes cholesterol from the liver and delivers it to the cells. This is the cholesterol which tends to be dropped along the arteries causing blockages. Both are necessary for overall health, but the balance that key. This balance appears to be different between the sexes. Women with low levels of good (HDL) cholesterol but high triglycerides (a kind of fat molecule) may be at increased risk of CHD. Men on the other hand find high levels of bad cholesterol (LDL) more problematic. High levels of triglycerides appear to be much more of a worry for women than they do men.
High cholesterol levels are due to a number of factors, including:
High blood pressure is also known as hypertension. Blood pressure is a measurement of the force against the walls of the arteries as the heart pumps blood through the body. If the pressure is too high it can damage the heart and this is linked to CHD and it's manifestations including angina, myocardial infarction (heart attack) and sudden cardiac arrest. Hypertension is also one of the leading causes of hert failure in women. One study showed that people between the age of 60 and 69 had a 1/5 lower risk of developing CHD by lowering their systolic blood pressure by just 10 mmHg. This was consistent with both men and women. Blood pressure readings are measured in millimeters of mercury (mmHg) and are usually given in two numbers, for example 120/80. Either or both of these numbers can be too high. The first number is the systolic pressure and it is considered too high over 140 and normal if it’s below 120. The second number is the diastolic pressure which is too high at 90 and normal under 80.
Both women and men with diabetes mellitus are in a higher risk category for CHD, although the risk is far higher for women. In fact women with diabetes are twice as likely to develop CHD as women who do not have the condition. One could say that this risk alone wipes out any statistical advantage women have over men when it comes to heart disease. To read more, see: Coronary heart disease in women.
Recognize the Signs?
One US survey showed that nearly 70 percent of women do not get enough exercise, putting them at higher risk of CHD. Although many surveys indicate that women have a more sedentary lifestyle than men, this fact remains questionable. Lots of questionnaires are primarily developed for men and focus on extra-curricular physical activities like sports, they often overlook other ways women expend energy such as housework, gardening and child minding. Either way, it is clear that both men and women in general do not exercise enough.
Middle aged women who smoke are far more prone to heart attacks related to smoking than their male counterparts. In fact 50 percent of all heart attacks in women can be attributed to tobacco. This is one of the reasons why public health officials are concerned about the increasing number of young women taking up the habit. If you do smoke, quitting is an important part of any coronary heart disease prevention program. See also what is considered middle aged?
Obesity is considered a risk factor for men, but only because men who are obese usually have other CHD risk factors at the same time like high blood pressure. Whereas for women, simply being obese, even without other factors, puts them at risk. Body shape may also be a factor. The incidence of heart disease and diabetes appears to be higher in women who are apple-shaped (fat stored around the tummy) rather than pear-shaped (fat mostly around the hips and thighs). Ideally a woman should have a waist circumference of less than 80cm (32 inches).
Women who have a close male relative (brother, father, grandfather) who had a heart attack before the age of 55 or a mother, sister, grandmother who had a heart attack before the age of 65 are at increased risk.
Women who have high levels of c-reactive protein (CRP) and/or homocysteine in their blood appear at increased risk of CHD. Large amounts of folate and vitamin B6 appear to help lower homocysteine levels and thus CHD risk. A CRP test, known as a high-sensitivity C-reactive protein (hs-CRP) assay can determine a person's risk of heart disease. However whether a high CRP level is an indicator of cardiovascular disease or a cause is not yet clear. See also Heart disease tests.
|Related Articles on Causes of CHD in Women
For more heart concerns, see the following:
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