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Saturday, July 18, 2009
Coronary heart disease and risk factors
Coronary heart disease and risk factors
(literature review of my Research Project do not copy without permission)
Introduction
Coronary heart disease (CHD) remains the leading cause of death and disability in developed countries and the rates are rapidly increasing in developing countries. About 13 million Americans have CHD and 1.5 million get a myocardial infarction (MI) each year, and about 450 000 die of CHD each year.
CHD is mainly caused by atherosclerosis, a process which alters endothelial function, by causing structural and functional obstructions in arteries. The risk of getting CHD is associated with hypertension, obesity, inactivity, diabetes, smoking, dietary factors, elevated homocysteine concentrations, elevated lipoprotein levels and some unchangeable factors such as age, male gender and genetics.
Atherogenesis is a long-drawn-out process which starts from the childhood. Cholesterol filled fatty steaks develop on the intima of the arteries which gradually enlarge and harden over the time, obstructing blood flow to the heart. These are called atheromatus plaques and the process is accelerated through exposure to the risk factors. Plaques may rupture, and the thrombus that forms to repair the damage occludes the artery resulting angina pectoris (chest pain due to low blood supply to heart muscle) or in severe cases myocardial infarction (death of heart muscle).
Although some risk factors are fixed, mortality and disability from CHD can be successfully controlled by modifying environmental factors. Therefore it is necessary to understand in-depth, how risk factors increase the risk and how they are controlled. Other than that studies about protective effects of different food items and life time patterns are essential to minimize CHD risk.
Un adjustable risk factors of CHD
Age
Likelihood of developing CHD dramatically increases with the age in both sexes. Age related degeneration and structural changes in arterial walls, cumulative effect of lifetime exposures of arteries to plasma lipoproteins, repeated damages to the arteries, age related increase in arterial pressure and alteration in endocrine functions, altogether accelerate the atherogenesis in older age.
Gender
Gender bias characteristics of CHD favors women by occurring, CHD in women 10-12 years later than in men. This raises the mean age at death from CHD in females and contributes to their greater longevity.
The reason for gender gap is suggested as higher estrogen levels in pre-menopause women, which acts protectively against CHD by lowering LDL-cholesterol and increasing HDL-cholesterol levels. However after the menopause, women’s blood cholesterol levels begin to rise and CHD risk comes closer to men’s. To avoid that estrogen replacement therapy is widely practiced in menopause women; although it is still controversial about some cancer risks.
Heredity
Hereditary and genetic variations such as, race, elevated homocystein levels and abnormalities in lipoproteins and their metabolism too affect the CHD risk in different extents. Studies found certain ethnic groups including, African Americans, Native Americans, Native Hawaiians and some Asian Americans and children of parents with heart diseases have increases risk of developing CHD.
Modifiable risk factors of CHD.
Increased arterial pressure
Hypertension or increased arterial pressure is a key factor which associates with the development of atherosclerosis, though this process does not develop on the venous side of the circulation. A systolic blood pressure >140 mm Hg and a diastolic blood pressure >90 mm Hg, or both in resting position, is universally considered as hypertension.
Constant exposure to increased arterial pressure can damage the arteries and rupture the atheromatus plaques, thereby the thrombus formation take place and lead to MI by occluding coronary artery.
Arterial pressure of adults is categorized as below.
____________________________________________
Categery Systolic Diastolic
Hgmm Hgmm
____________________________________________
Normal <120>160 >100
____________________________________________
Arterial pressure can be successfully controlled through dietary and behavioral modifications, such as antihypertensive medications, salt restricted diets, physical activities and stress reduction.
Hypercholesterolemia
Elevated lipoprotein levels in blood are another critical factor for CHD. It is found that CHD is uncommon in societies with mean serum total cholesterol concentrations <> 160 mg/dl and HDL-< 35 mg/dl.
Other than LDL, Triacylglycerol (TAG) and Lipoprotein (a) are the other lipoproteins which increase the CHD risk.
Many dietary surveys and experimental studies showed a reduction in LDL, TAG and total cholesterol levels and increase in HDL levels in modified and some traditional diets. A crossover study done by Rndeau et al, 2001 found a significant increase in HDL2 in hypercholesterolemic men during lean fish diet.
Smoking
Smoking is a well established risk factor for CHD and many other non communicable diseases.
Physical inactivity
Follow-up studies showed increased risk of getting CHD amongst sedentary people than in people who are physically active. Physical activities clearly showed a decrease in LDL cholesterol and an increase in HDL cholesterol. It improves overall function of circulatory system and it is more effective than dietary modifications.
(literature review of my Research Project do not copy without permission)
Introduction
Coronary heart disease (CHD) remains the leading cause of death and disability in developed countries and the rates are rapidly increasing in developing countries. About 13 million Americans have CHD and 1.5 million get a myocardial infarction (MI) each year, and about 450 000 die of CHD each year.
CHD is mainly caused by atherosclerosis, a process which alters endothelial function, by causing structural and functional obstructions in arteries. The risk of getting CHD is associated with hypertension, obesity, inactivity, diabetes, smoking, dietary factors, elevated homocysteine concentrations, elevated lipoprotein levels and some unchangeable factors such as age, male gender and genetics.
Atherogenesis is a long-drawn-out process which starts from the childhood. Cholesterol filled fatty steaks develop on the intima of the arteries which gradually enlarge and harden over the time, obstructing blood flow to the heart. These are called atheromatus plaques and the process is accelerated through exposure to the risk factors. Plaques may rupture, and the thrombus that forms to repair the damage occludes the artery resulting angina pectoris (chest pain due to low blood supply to heart muscle) or in severe cases myocardial infarction (death of heart muscle).
Although some risk factors are fixed, mortality and disability from CHD can be successfully controlled by modifying environmental factors. Therefore it is necessary to understand in-depth, how risk factors increase the risk and how they are controlled. Other than that studies about protective effects of different food items and life time patterns are essential to minimize CHD risk.
Un adjustable risk factors of CHD
Age
Likelihood of developing CHD dramatically increases with the age in both sexes. Age related degeneration and structural changes in arterial walls, cumulative effect of lifetime exposures of arteries to plasma lipoproteins, repeated damages to the arteries, age related increase in arterial pressure and alteration in endocrine functions, altogether accelerate the atherogenesis in older age.
Gender
Gender bias characteristics of CHD favors women by occurring, CHD in women 10-12 years later than in men. This raises the mean age at death from CHD in females and contributes to their greater longevity.
The reason for gender gap is suggested as higher estrogen levels in pre-menopause women, which acts protectively against CHD by lowering LDL-cholesterol and increasing HDL-cholesterol levels. However after the menopause, women’s blood cholesterol levels begin to rise and CHD risk comes closer to men’s. To avoid that estrogen replacement therapy is widely practiced in menopause women; although it is still controversial about some cancer risks.
Heredity
Hereditary and genetic variations such as, race, elevated homocystein levels and abnormalities in lipoproteins and their metabolism too affect the CHD risk in different extents. Studies found certain ethnic groups including, African Americans, Native Americans, Native Hawaiians and some Asian Americans and children of parents with heart diseases have increases risk of developing CHD.
Modifiable risk factors of CHD.
Increased arterial pressure
Hypertension or increased arterial pressure is a key factor which associates with the development of atherosclerosis, though this process does not develop on the venous side of the circulation. A systolic blood pressure >140 mm Hg and a diastolic blood pressure >90 mm Hg, or both in resting position, is universally considered as hypertension.
Constant exposure to increased arterial pressure can damage the arteries and rupture the atheromatus plaques, thereby the thrombus formation take place and lead to MI by occluding coronary artery.
Arterial pressure of adults is categorized as below.
____________________________________________
Categery Systolic Diastolic
Hgmm Hgmm
____________________________________________
Normal <120>160 >100
____________________________________________
Arterial pressure can be successfully controlled through dietary and behavioral modifications, such as antihypertensive medications, salt restricted diets, physical activities and stress reduction.
Hypercholesterolemia
Elevated lipoprotein levels in blood are another critical factor for CHD. It is found that CHD is uncommon in societies with mean serum total cholesterol concentrations <> 160 mg/dl and HDL-< 35 mg/dl.
Other than LDL, Triacylglycerol (TAG) and Lipoprotein (a) are the other lipoproteins which increase the CHD risk.
Many dietary surveys and experimental studies showed a reduction in LDL, TAG and total cholesterol levels and increase in HDL levels in modified and some traditional diets. A crossover study done by Rndeau et al, 2001 found a significant increase in HDL2 in hypercholesterolemic men during lean fish diet.
Smoking
Smoking is a well established risk factor for CHD and many other non communicable diseases.
Physical inactivity
Follow-up studies showed increased risk of getting CHD amongst sedentary people than in people who are physically active. Physical activities clearly showed a decrease in LDL cholesterol and an increase in HDL cholesterol. It improves overall function of circulatory system and it is more effective than dietary modifications.
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