Capítulo 2 Contexto en el que se desenvuelven las actividades que apoya el
2.1 Caracterización general de la economía rural
factors
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People are not at equal risk for heart disease. Atherosclerotic lesions can develop early, sometimes even in adolescence. However, they form even earlier in the presence of known cardiovascular risk factors.
Risk factors include behaviors, situations, or antecedents that influence the frequency of heart problems.
A predisposing factor can be defined as a physiological state (e.g. age), pathological condition (e.g. hypertension), or a habit (smoking, for example) that is associated with a higher rate of occurrence.
Cardiovascular risk factors are:
• age and sex: over age 50 years in men, and age 60 years in women
• smoking: current or having quit for less than 3 years
• diabetes: treated or not
• arterial hypertension: treated or not • heredity
• an excess of ‘bad’ cholesterol, insufficient ‘good’ cholesterol, or both
• obesity or overweight • sedentary lifestyle • stress
• alcohol.
4.1 AGE AND SEX
Arteries lose elasticity and become more rigid with age. Atheromatous plaque forms on the artery walls and these endothelial lesions can be the starting point for cardiovascular problems.
The probability of cardiac disorders or cer- ebral vascular accident rises sharply after the age of 50 years in men and 60 years in women. The variation in cardiovascular rates between the sexes is most likely explained by hormo- nal differences.
• Before menopause, women have a reduced risk.
• After menopause, when estrogen falls, cardiovascular disease rises sharply in women and reaches that of men of the same age.
• Several years after the menopause, women are at higher risk than men.
4.2 SMOKING
Smoking is directly or indirectly responsible for many deaths. Aside from the numerous lung pathologies it causes, tobacco is a key factor in cardiovascular disease.
Smoking is linked particularly to the sudden death associated with myocardial inf- arction. Smoking 10 cigarettes a day doubles the risk of a heart attack. Smoking 20 ciga- rettes daily increases the risk threefold com- pared with that in a non-smoker.
Passive smoke inhalation presents the same health risk. It has been demonstrated than a nonsmoking spouse married to a smoker has a 25% increased risk of infarction.
The benefits of quitting are progressive. Two to three years after quitting, the coronary ©2011 Elsevier Ltd
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risk is still not significantly different from that of a smoker.
However, in the case of myocardial infarc- tion, the risk of recurrence or death dimin- ishes significantly after the first year of quitting and eventually falls to the same risk level as that in nonsmokers.
4.3 DIABETES
The consequences of diabetes carry numerous health risks. Excess blood glucose over many years is toxic to the arteries and the nervous system.
In terms of small arteries, diabetes chiefly affects the eyes and the kidneys:
• In the eyes, the disease creates
retinopathy, which manifests as visual disturbances and can eventually cause blindness. Diabetes is the principal cause of adult blindness.
• In the kidneys, arteriopathy – ‘disease of the artery’ – can evolve into chronic renal insufficiency requiring dialysis, and even renal transplantation.
In large arteries, diabetes favors the forma- tion of atheromatous plaque, greatly increas- ing cardiovascular risk. The three target areas are:
1 The heart: coronary heart disease and angina pectoris
2 The brain: affected carotid arteries can be the source of cerebrovascular accidents
3 The lower extremities: there is a predisposition to the development of arteriosclerosis obliterans of the lower extremity.
Nerves can suffer diabetic neuropathy, bring- ing with it intractable leg pain. Frequency increases with the duration of the diabetes and the age of the person affected. Such neu- ropathy linked with affliction to the smaller vessels can cause wounds to the foot leading to amputation.
4.4 ARTERIAL HYPERTENSION
The link between cardiovascular tension and risk is well established. The incidence ofhypertension is particularly high in industri- alized countries. Often it has no identifiable origin and for this reason is called essential
hypertension.
Nevertheless, in some cases there are known causes (alcohol, drugs such as corti- costeroids, oral contraceptives, cocaine, ecstasy, and certain illnesses, notably renal disease), in which case the term secondary
hypertension applies.
Arterial hypertension is usually silent; it has no symptoms or visible sign and is there- fore called the ‘silent killer’. It is detectable only through regular blood pressure testing.
Large-scale epidemiological studies show that the relationship between arterial pressure and cerebral risk is greater than the relation- ship between arterial pressure and coronary risk.
Arteriosclerosis (hardening of the arteries)
linked specifically to high blood pressure (HBP) and aging is distinguished from the process of atherosclerosis (formation of plaque) in which HBP does not intervene except as a general risk factor. Arteriosclerosis is mainly a pathology of the intima of the large arterial vessel walls, notably in the areas of turbulent flux.
In the brain, arteriosclerosis is implicated in at least 50% of cardiovascular accidents. It is responsible for the small cerebral infarcts resulting from the occlusion of perforating arteries. Atherosclerosis is responsible for one-third of cerebral lesions in people with hypertension. It causes large cerebral infarcts. Hemorrhage occurs in only 20% of cases.
In the heart HBP:
• favors the formation of atheromatous plaque in the large coronary trunks responsible for ‘organic’ cardiac insufficiency
• contributes, in collaboration with various neurohormonal factors, to hypertrophy of the left ventricle. This hypertrophy then contributes to structural and functional anomalies of the small coronary arteries,
further contributing to coronary insufficiency.
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Cardiovascular risk factors
4.5 HEREDITY
Heredity is a major risk factor for cardiovas- cular disease. Illness in the immediate family (father, mother, or sibling) is especially sig- nificant. Even one such family member suf- fering from heart disease increases the chances of it developing.
Nevertheless, only cardiovascular accidents occurring early are taken into consideration: • sudden death from myocardial infarcts:
– before age 55 in the brother or father – before age 65 in the mother or sister. • Cerebrovascular accidents in a member of
the family before age 45.
4.6 BLOOD LIPIDS
The link between hypercholesterolemia and atherosclerosis is particularly well established, essentially in regard to coronary pathology.
Cholesterol is widely distributed in the tissues and fluids of the body. This sterol, which stabilizes lipids, is necessary for the formation of sex hormones, corticoids, and bile. Part of cholesterol derives directly from food, but it is synthesized mainly in the liver.
After reaching the various tissues of the body via the blood, cholesterol attaches to the plasma transporters. These complexes, called lipoproteins, are classed according to density.
• Low density lipoprotein (LDL) transports cholesterol from the liver to the cells of the body that require LDL for the function and reconstruction of their cell membranes. Low density lipoproteins have a tendency to form fatty deposits on the lining of the artery wall. Increased LDL in plasma is associated with an increased risk of atherosclerosis, and is thus termed ‘bad cholesterol.’
• High density lipoprotein (HDL) collects and converts cholesterol and carries it to the liver for removal from the body. Thus, HDL serves to protect the artery walls. When HDL levels are low, their protection becomes insufficient. A concentration of HDL lower than 0.35 g
(French recommendation) or 0.4 g (American recommendation) is thus considered an additional cardiovascular risk factor.
4.7 OVERWEIGHT AND OBESITY
Body mass index (BMI) is a measure of body fat based on height and weight:• BMI 20–25 kg/m2: normal weight
• BMI 25–30 kg/m2: overweight
• BMI ≥30 kg/m2: obese
• BMI >40 kg/m2: morbidly obese.
Overweight and certainly obesity are clearly associated with a raised coronary risk. This increase is dependent partly on the impact of excess weight on other risk factors. Remember that each kilogram of extra fat adds 650 km to the length of the vascular network!
More than 75% of cases of arterial hyper- tension are due, in part, to excess weight. Today, obesity is on the rise. Indeed practi- cally half of the inhabitants of rich countries are overweight.
Besides being overweight, weight distribu- tion has as impact. Excess abdominal fat increases cardiovascular risk. This can be measured by the waist to hip ratio or by the waist circumference alone.
A ratio >0.95 in men and >0.80 in women indicates cardiovascular risk.
Excess abdominal fat is strongly associated with a number of disturbances, making up what has been designated Syndrome X. This metabolic disease is a combination of medical disorders, among which are found:
• insulin resistance, hypoglycemia, or type II diabetes
• hyperlipidemia, typically found with raised triglyceride and HDL levels • a tendency towards arterial hypertension.
4.8 SEDENTARY LIFESTYLE
Regular physical exercise is associated with both a lower heart rate and decreased blood pressure, thus reducing the oxygen require- ment of the myocardium. In addition, physi- cal exercise helps to keep weight in check,
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lowers triglyceride levels, increases HDL con- centrations, diminishes plaque aggregation, lowers the sympathetic stress response, and stimulates fibrinolysin (an enzyme that pro- motes the dissolution of thrombi).
For the majority of urban dwellers, ener- getic expenditure is limited to leisure activi- ties. A meta-analysis (Berlin & Colditz 1990) combining the results of several studies found that a sedentary lifestyle increases the risk of dying from heart trouble 1.9-fold.
As therapists, it is important that we rec- ommend that patients practice at least 30 min of moderate physical exercise daily, which amounts to 30 min of brisk walking.
4.9 STRESS
It has taken the scientific community a number of years to admit that stress is an integral part of cardiovascular risk. Stress is an interaction between the individual and the constraints of their environment. Cardiovas- cular risk is linked more to the response of the individual than to the circumstances themselves.
Stress can be divided in two categories: 1 Emotional factors such as anxiety,
depression, relationship problems, or the inability to express anger.
2 Chronic stress, connected with low socioeconomic status, overwork, or a weak social network.
Psychosocial stress develops when there is an imbalance between the stress load (all the
demands arising from the environment, our- selves, our daily responsibilities, and extrane- ous events) and our capacity to face these difficulties.
This imbalance bring with it signs of stress in our feelings, thoughts, behavior, and body, which can aggravate and maintain the problem.
Stress increases sympathetic activity and causes a rise in the blood levels of catecho- lamines such as epinephrine (adrenaline). Raised catecholamine levels contribute to an increase in cholesterol and blood sugar con- centrations, in turn causing blood pressure to rise and reducing the flexibility of fluctua- tions in cardiac rhythm (Black & Garbutt 2002).
The most common alarm signs of stress are difficulty falling asleep and/or early waking, persistent fatigue, muscle tension in the jaw, neck, and shoulders, diminished power of recuperation, reduced ability to concentrate, failing short-term memory, and agoraphobia.
4.10 ALCOHOL
In a person suffering from hypertension, excessive alcohol consumption is calculated to be: more than three glasses of wine per day in men and two glasses in women (Haute Autorité de Santé 2005). Taking into account the cumulative effect, three glasses of wine per day adds up to about 120 bottles per year!
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