Monday, January 6, 2014

CARDIOVASCULAR DISEASE

Cardiovascular disease (also called heart disease) is a class of diseases that involve the heart, the blood vessels (arteries,capillaries, and veins) or both.[1]
Cardiovascular disease refers to any disease that affects the cardiovascular system, principally cardiac disease, vascular diseases of the brain and kidney, and peripheral arterial disease.[2] The causes of cardiovascular disease are diverse but atherosclerosis and/orhypertension are the most common. Additionally, with aging come a number of physiological and morphological changes that alter cardiovascular function and lead to subsequently increased risk of cardiovascular disease, even in healthy asymptomatic individuals.[3]
Cardiovascular disease is the leading cause of deaths worldwide, though since the 1970s, cardiovascular mortality rates have declined in many high-income countries.[4][5] At the same time, cardiovascular deaths and disease have increased at a fast rate in low- and middle-income countries.[6] Although cardiovascular disease usually affects older adults, the antecedents of cardiovascular disease, notably atherosclerosis, begin in early life, making primary prevention efforts necessary from childhood.[7] There is therefore increased emphasis on preventing atherosclerosis by modifying risk factors, such as healthy eating, exercise, and avoidance of smoking tobacco.

Risk factors[edit]

Evidence suggests a number of risk factors for heart disease: age, gender, high blood pressure, high serum cholesterol levels, tobacco smoking, excessive alcohol consumption, sugar consumption,[9][10] family history, obesity, lack of physical activity, psychosocial factors, diabetes mellitus, air pollution.[2] While the individual contribution of each risk factor varies between different communities or ethnic groups the consistency of the overall contribution of these risk factors to epidemiological studies is remarkably strong.[11] Some of these risk factors, such as age, gender or family history, are immutable; however, many important cardiovascular risk factors are modifiable by lifestyle change, drug treatment or social change.

CATEOGORIES

Risk factors[edit]

Evidence suggests a number of risk factors for heart disease: age, gender, high blood pressure, high serum cholesterol levels, tobacco smoking, excessive alcohol consumption, sugar consumption,[9][10] family history, obesity, lack of physical activity, psychosocial factors, diabetes mellitus, air pollution.[2] While the individual contribution of each risk factor varies between different communities or ethnic groups the consistency of the overall contribution of these risk factors to epidemiological studies is remarkably strong.[11] Some of these risk factors, such as age, gender or family history, are immutable; however, many important cardiovascular risk factors are modifiable by lifestyle change, drug treatment or social change.
Age
Age is by far the most important risk factor in developing cardiovascular diseases, with approximately a tripling of risk with each decade of life.[6] It is estimated that 82 percent of people who die of coronary heart disease are 65 and older.[12] At the same time, the risk of stroke doubles every decade after age 55.[13]
Multiple explanations have been proposed to explain why age increases the risk of cardiovascular diseases. One of them is related to serum cholesterol level.[14] 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.[14]
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

Prevention[edit]

Currently practiced measures to prevent cardiovascular disease include:
  • A low-fat, high-fiber diet including whole grains and plenty of fresh fruit and vegetables (at least five portions a day)[34][35]
  • Tobacco cessation and avoidance of second-hand smoke;[34]
  • Limit alcohol consumption to the recommended daily limits;[34] consumption of 1-2 standard alcoholic drinks per day may reduce risk by 30%[36][37] However excessive alcohol intake increases the risk of cardiovascular disease.[38]
  • Lower blood pressures, if elevated;
  • Decrease body fat (BMI) if overweight or obese;[39]
  • Increase daily activity to 30 minutes of vigorous exercise per day at least five times per week;[34]
  • Reduce sugar consumptions;
  • Decrease psychosocial stress.[40] Stress however plays a relatively minor role in hypertension.[41] Specific relaxation therapies are not supported by the evidence.[42]
For adults without a known diagnosis of hypertension, diabetes, hyperlipidemia, or cardiovascular disease, routine counseling to advise them to improve their diet and increase their physical activity has not been found to significantly alter behavior, and thus is not recommended.[43]

Diet[edit]

Evidence suggests that the Mediterranean diet improves cardiovascular outcomes.[44] This may be by about 30% in those at high risk.[45] There is also evidence that a Mediterranean diet may be more effective than a low-fat diet in bringing about long-term changes to cardiovascular risk factors (e.g., lower cholesterol level and blood pressure).[46]The DASH diet (high in nuts, fish, fruits and vegetables, and low in sweets, red meat and fat) has been shown to reduce blood pressure,[47] lower total and low density lipoprotein cholesterol [48] and improve metabolic syndrome;[49] but the long term benefits outside the context of a clinical trial have been questioned.[50] A high fiber diet appears to lower the risk.[51]
Total fat intake does not appear to be an important risk factor.[52] A diet high in trans fatty acids however does appear to increase rates of cardiovascular disease.[52][53] Worldwide, dietary guidelines recommend a reduction in saturated fat.[54] There however are some questions around the effect of saturated fat on cardiovascular disease in the medical literature.[55][56] A 2012 Cochrane review found suggestive evidence of a small benefit from replacing dietary saturated fat by unsaturated fat.[57] A 2013 meta analysis concludes that substitution with omega 6 linoleic acid (a type of unsaturated fat) may increase cardiovascular risk.[54] Replacement of saturated fats with carbohydrates does not change or may increase risk.[58][59] Benefits from replacement with polyunsaturated fat appears greatest[52][60] however supplementation with omega-3 fatty acids (a type of polysaturated fat) does not appear have an effect.[61]
The effect of a low salt diet is unclear. A Cochrane review concluded that any benefit in either hypertensive or normal tensive people is small if present.[62] Additionally, the review suggested a low salt diet may be harmful in those with congestive heart failure.[62] However, the review was criticized particularly for not excluding a trial in heart failure where people had low salt and water levels due to diuretics.[63] When this study is left out the rest of the trials show a trend to benefit.[63][64] Another review of dietary salt concluded that there is strong evidence that high dietary salt intake increases blood pressure and worsens hypertension, and that it increases the number of cardiovascular disease events; the latter happens both through the increased blood pressure and, quite likely, through other mechanisms.[65][66] Moderate evidence was found that high salt intake increased cardiovascular mortality; and some evidence was found for an increase in overall mortality, strokes and left-ventricular hypertrophy.[65]

Supplements[edit]

While a healthy diet is beneficial, the effect of antioxidant supplementation (vitamin E, vitamin C, etc.) or vitamins generally has not been shown to improve protection against cardiovascular disease and in some cases may possibly result in harm.[67][68] Niacin, a type of vitamin B3, may be an exception with a modest decrease in the risk of cardiovascular events in those at high risk.[69][70] Magnesium supplementation lowers high blood pressure in a dose dependent manner.[71] Magnesium therapy is recommended for patients with ventricular arrhythmia associated with torsade de pointes who present with long QT syndrome as well as for the treatment of patients with digoxin intoxication-induced arrhythmias.[72] Results from an observational study conducted in the general Japanese population demonstrated that lower serum magnesium levels were associated with a greater average intima-media thickness and the risk of at least two carotid plaques.[73] Evidence to support omega-3 fatty acid supplementation is lacking.[74]

Medication[edit]

Aspirin has not been found to be of benefit overall in those at low risk of heart disease as the risk of serious bleeding is equal to the benefit with respect to cardiovascular problems.[75]
Statins are effective in preventing further cardiovascular disease in those with a history of cardiovascular disease.[76] As the event rate is higher in men than in women, the decrease in events is more easily seen in men than women.[76] In those without cardiovascular disease but risk factors statins appear to also be beneficial with a decrease in mortality and further heart disease.[77] The time course over which statins provide preventation against death appears to be long, of the order of one year, which is much longer than the duration of their effect on lipids.[78]

Management[edit]

Cardiovascular disease is treatable with initial treatment primarily focused on diet and lifestyle interventions.