Cardiovascular disease
Cardiovascular disease
Cardiovascular disease (CVD) is a class of diseases that
involve the heart or blood vessels. Cardiovascular disease includes coronary artery
diseases (CAD) such as angina and myocardial infarction (commonly known as a heart
attack).Other CVDs are stroke, heart failure, hypertensive
heart disease, rheumatic heart
disease, cardiomyopathy, heart arrhythmia, congenital heart
disease, valvular heart
disease, carditis, aortic aneurysms, peripheral artery
disease, and venous thrombosis.
The underlying mechanisms vary depending on the disease in
question. Coronary artery disease, stroke, and peripheral artery disease
involve atherosclerosis. This may be caused by high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol,
poor diet, and excessive alcohol consumption, among others. High blood
pressure results in 13% of CVD deaths, while tobacco results in 9%, diabetes
6%, lack of exercise 6% and obesity 5%. Rheumatic heart disease may follow
untreated strep throat.
It is estimated that 90% of CVD is preventable. Prevention of atherosclerosis involves
improving risk factors through: healthy eating, exercise, avoidance of tobacco
smoke and limiting alcohol intake. Treating
high blood pressure, blood lipids and diabetes is also beneficial. Treating people who have strep throat
with antibiotics can
decrease the risk of rheumatic heart disease. The
effect of the use of aspirin in
people who are otherwise healthy is of unclear benefit. The United
States Preventive Services Task Force recommends against its use for
prevention in women less than 55 and men less than 45 years old; however, in
those who are older it is recommends in some individuals. Treatment of those who have CVD improves
outcomes.
Cardiovascular diseases are the leading cause of death globally. This is true in all areas of the world
except Africa.Together they resulted in 17.3 million deaths (31.5%) in 2013 up
from 12.3 million (25.8%) in 1990. Deaths, at a given
age, from CVD are more common and have been increasing in much of
the developing world, while rates have declined in
most of the developed world since the 1970s. Coronary artery disease and stroke
account for 80% of CVD deaths in males and 75% of CVD deaths in females.[1] Most cardiovascular disease affects older
adults. In the United States 11% of people between 20 and 40 have CVD, while
37% between 40 and 60, 71% of people between 60 and 80, and 85% of people over
80 have CVD. The average age of
death from coronary artery disease in the developed world is around 80 while it
is around 68 in the developing world. Disease
onset is typically seven to ten years earlier in men as compared to women.
Types
Disability-adjusted
life year for
inflammatory heart diseases per 100,000 inhabitants in 2004[12]
There are many cardiovascular diseases involving the blood
vessels. They are known as vascular diseases.
·
Coronary artery
disease (also known as
coronary heart disease and ischemic heart disease)
·
Peripheral
arterial disease –
disease of blood vessels that supply blood to the arms and legs
·
Cerebrovascular
disease – disease of
blood vessels that supply blood to the brain (includes stroke)
·
Renal artery stenosis
·
Aortic aneurysm
There are also many cardiovascular diseases that involve the
heart.
·
Cardiomyopathy – diseases of cardiac muscle
·
Hypertensive
heart disease –
diseases of the heart secondary to high blood pressure or hypertension
·
Heart failure - a clinical syndrome caused by the
inability of the heart to supply sufficient blood to the tissues to meet their
metabolic requirements
·
Pulmonary heart disease – a failure at the right side of the
heart with respiratory system involvement
·
Cardiac dysrhythmias – abnormalities of heart rhythm
·
Inflammatory heart disease
·
Endocarditis – inflammation of
the inner layer of the heart, the endocardium. The structures most commonly
involved are the heart valves.
·
Inflammatory cardiomegaly
·
Myocarditis – inflammation of the myocardium, the muscular part of the heart.
·
Valvular heart
disease
·
Congenital heart
disease – heart
structure malformations existing at birth
·
Rheumatic heart
disease – heart
muscles and valves damage due to rheumatic fever caused by Streptococcus
pyogenes a group A
streptococcal infection.
Risk
factors
There are several risk factors for heart diseases: age, gender,
tobacco use, physical inactivity, excessive alcohol consumption,
unhealthy diet, obesity, family history of cardiovascular disease, raised blood
pressure (hypertension),
raised blood sugar (diabetes mellitus),
raised blood cholesterol (hyperlipidemia),
psychosocial factors, poverty and low educational status, and air pollution. While
the individual contribution of each risk factor varies between different
communities or ethnic groups the overall contribution of these risk factors is
very consistent. Some of these
risk factors, such as age, gender or family history, genetic, are immutable;
however, many important cardiovascular risk factors are modifiable by lifestyle
change, social change, drug treatment and prevention of hypertension,
hyperlipidemia, and diabetes.
Genetics
Cardiovascular disease in a person's parents increases their
risk by 3 fold.
Age
Calcified
heart of an older woman with cardiomegaly
Age is by far the most important risk factor in developing
cardiovascular or heart diseases, with approximately a tripling of risk with
each decade of life. Coronary
fatty streaks can begin to form in adolescence. 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/heart 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.
Sex
Men are at greater risk of heart disease than pre-menopausal
women. Once past menopause, it has been argued that a woman's risk is
similar to a man's although more
recent data from the WHO and UN disputes this. If a female has diabetes, she is more
likely to develop heart disease than a male with diabetes.
Coronary heart diseases are 2 to 5 times more common among
middle-aged men than women. In a
study done by the World Health Organization,
sex contributes to approximately 40% of the variation in sex ratios of coronary
heart disease mortality. Another
study reports similar results finding that gender differences explains nearly
half the risk associated with cardiovascular diseases One of the proposed explanations for
gender differences in cardiovascular diseases is hormonal difference. Among women, estrogen is the
predominant sex hormone. Estrogen may
have protective effects through glucose metabolism and hemostatic system, and
may have direct effect in improving endothelial cell
function. The production of
estrogen decreases after menopause, and this may change the female lipid
metabolism toward a more atherogenic form by decreasing the HDL cholesterol level while increasing LDL
and total cholesterol levels.
Among men and women, there are notable 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 among
women than men. This may be
caused by the women's smaller body size and arterial dimensions which are
independent of menopause.
Tobacco
Cigarettes are the major form of smoked tobacco. Risks to health from tobacco use
result not only from direct consumption of tobacco, but also from exposure to
second-hand smoke. Approximately
10% of cardiovascular disease is attributed to smoking; however, people who quit smoking by
age 30 have almost as low a risk of death as never smokers.
Physical inactivity
Insufficient physical activity (defined as less than 5 x 30
minutes of moderate activity per week, or less than 3 x 20 minutes of vigorous
activity per week) is currently the fourth leading risk factor for mortality
worldwide. In 2008, 31.3% of
adults aged 15 or older (28.2% men and 34.4% women) were insufficiently
physically active. The risk of
ischemic heart disease and diabetes mellitus is reduced by almost a third in
adults who participate in 150 minutes of moderate physical activity each week
(or equivalent). In addition,
physical activity assists weight loss and improves blood glucose control, blood
pressure, lipid profile and insulin sensitivity. These effects may, at least in
part, explain its cardiovascular benefits.
Diet
High dietary intakes of saturated fat, trans-fats and salt, and
low intake of fruits, vegetables and fish are linked to cardiovascular risk,
although whether all these associations are a cause is disputed. The World
Health Organization attributes approximately 1.7 million deaths worldwide to
low fruit and vegetable consumption. The
amount of dietary salt consumed is also an important determinant of blood
pressure levels and overall cardiovascular risk. Frequent consumption of high-energy
foods, such as processed foods that are high in fats and sugars, promotes
obesity and may increase cardiovascular risk. High trans-fat intake
has adverse effects on blood lipids and circulating inflammatory markers, and elimination of trans-fat from
diets has been widely advocated. There
is evidence that higher consumption of sugar is associated with higher blood
pressure and unfavorable blood lipids, and
sugar intake also increases the risk of diabetes mellitus. High consumption of processed meats is
associated with an increased risk of cardiovascular disease, possibly in part
due to increased dietary salt intake.
The relationship between alcohol consumption and cardiovascular
disease is complex, and may depend on the amount of alcohol consumed. There is
a direct relationship between high levels of alcohol consumption and risk of
cardiovascular disease. Drinking
at low levels without episodes of heavy drinking may be associated with a
reduced risk of cardiovascular disease. Overall
alcohol consumption at the population level is associated with multiple health
risks that exceed any potential benefits.
Socioeconomic disadvantage
Cardiovascular disease affects low- and middle-income countries
even more than high-income countries. There
is relatively little information regarding social patterns of cardiovascular
disease within low- and middle-income countries, but within high-income countries low
income and low educational status are consistently associated with greater risk
of cardiovascular disease. Policies
that have resulted in increased socio-economic inequalities have been
associated with greater subsequent socio-economic differences in cardiovascular
disease implying a cause and
effect relationship. Psychosocial factors, environmental exposures, health
behaviours, and health-care access and quality contribute to socio-economic
differentials in cardiovascular disease. The
Commission on Social Determinants of Health recommended that more equal
distributions of power, wealth, education, housing, environmental factors,
nutrition, and health care were needed to address inequalities in
cardiovascular disease and non-communicable diseases.
Air pollution
Particulate matter has been studied for its 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 PM2.5induced
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 hours), every 25 μg/m3 of PM2.5 resulted in a 48% increase of CVD mortality
risk. In addition, 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.
Cardiovascular risk assessment
Existing cardiovascular disease or a previous cardiovascular
event, such as a heart attack or stroke, is the strongest predictor of a future
cardiovascular event. Age, sex,
smoking, blood pressure, blood lipids and diabetes are important predictors of
future cardiovascular disease in people who are not known to have
cardiovascular disease.These measures, and sometimes others, may be combined
into composite risk scores to estimate an individual's future risk of
cardiovascular disease. Numerous
risk scores exist although their respective merits are debated. Other diagnostic tests and biomarkers
remain under evaluation but currently these lack clear-cut evidence to support
their routine use. They include family history, coronary artery calcification score, high
sensitivity C-reactive protein (hs-CRP), ankle
brachial index, lipoprotein subclasses and particle concentration,
lipoprotein(a), apolipoproteins A-I and B, fibrinogen, white blood cell count, homocysteine, N-terminal pro B-type natriuretic
peptide (NT-proBNP), and markers of kidney function.
Work
Main article: Occupational
cardiovascular disease
Little is known about the relationship between work and
cardiovascular disease, but links have been established between certain toxins,
extreme heat and cold, exposure to tobacco smoke, and mental health concerns
such as stress and depression.
Pathophysiology
Density-Dependent
Colour Scanning Electron Micrograph SEM (DDC-SEM) of cardiovascular
calcification, showing in orange calcium phosphate spherical particles (denser
material) and, in green, the extracellular matrix (less dense material)
Population-based studies show that atherosclerosis, the major
precursor of cardiovascular disease, begins in childhood. The Pathobiological
Determinants of Atherosclerosis in Youth Study demonstrated that intimal
lesions appear in all the aortas and more than half of the right coronary
arteries of youths aged 7–9 years.
This is extremely important considering that 1 in 3 people die
from complications attributable to atherosclerosis. In order to stem the tide,
education and awareness that cardiovascular disease poses the greatest threat,
and measures to prevent or reverse this disease must be taken.
Obesity and diabetes mellitus are
often linked to cardiovascular disease, as
are a history of chronic kidney disease and hypercholesterolaemia. In fact, cardiovascular disease is the
most life-threatening of the diabetic complications and diabetics are two- to
four-fold more likely to die of cardiovascular-related causes than
nondiabetics.
Screening
Screening ECGs (either at rest or with exercise) are
not recommended in those without symptoms who are at low risk. This includes those who are young
without risk factors. In those at
higher risk the evidence for screening with ECGs is inconclusive.
Additionally echocardiography, myocardial perfusion
imaging, and cardiac stress testing is not recommended in those at low risk
who do not have symptoms.
Some biomarkers may add to conventional cardiovascular
risk factors in predicting the risk of future cardiovascular disease; however,
the clinical value of some biomarkers is questionable.
The NIH recommends lipid testing in children beginning at the
age of 2 if there is a family history of heart disease or lipid problems. It is hoped that early testing will
improve lifestyle factors in those at risk such as diet and exercise.
Prevention
Up to 90% of cardiovascular disease may be preventable if
established risk factors are avoided. Currently
practiced measures to prevent cardiovascular disease include:
·
A low-fat, high-fiber diet including
whole grains and fruit and vegetables. Five
portions a day reduces risk by about 25%.
·
Tobacco cessation
and avoidance of second-hand smoke
·
Limit alcohol consumption to the recommended daily limits; consumption of 1–2 standard alcoholic
drinks per day may reduce risk by 30%. However,
excessive alcohol intake increases the risk of cardiovascular disease.
·
Lower blood pressures, if elevated
·
Decrease non-HDL cholesterol.
·
Decrease body fat if overweight or obese
·
Increase daily activity to 30 minutes of vigorous exercise per
day at least five times per week (multiply by three if horizontal);
·
Reduce sugar consumptions
·
Decrease psychosocial stress. This measure may be complicated by
imprecise definitions of what constitute psychosocial interventions. Mental stress–induced myocardial ischemia is associated with an increased risk
of heart problems in those with previous heart disease. Severe emotional and physical stress
leads to a form of heart dysfunction known as Takotsubo syndrome in some people. Stress, however, plays a relatively
minor role in hypertension. Specific
relaxation therapies are of unclear benefit.
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. It is unclear whether or not dental
care in those with periodontitis affects
the risk of cardiovascular disease. Exercise
in those who are at high risk of heart disease has not been well studied as of
2014.
Diet
See also: Saturated fat and cardiovascular disease controversy and Salt and
cardiovascular disease
A diet high in fruits and vegetables decreases the risk of
cardiovascular disease and death. Evidence suggests that the Mediterranean diet may improve cardiovascular outcomes. 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). 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, lower
total and low density lipoprotein cholesterol and
improve metabolic syndrome; but the long-term benefits outside the
context of a clinical trial have been questioned. A high fiber diet appears
to lower the risk.
Total fat intake does not appear to be an important risk factor. A diet high in trans fatty acids, however, does appear to increase
rates of cardiovascular disease.Worldwide, dietary guidelines recommend a
reduction in saturated fat. However,
there are some questions around the effect of saturated fat on cardiovascular
disease in the medical
literature. Reviews from 2014 and
2015 did not find evidence of harm from saturated fats. A 2012 Cochrane review found
suggestive evidence of a small benefit from replacing dietary saturated fat by
unsaturated fat. A 2013 meta
analysis concludes that substitution with omega 6 linoleic acid (a type of unsaturated fat) may
increase cardiovascular risk. Replacement
of saturated fats with carbohydrates does
not change or may increase risk. Benefits
from replacement with polyunsaturated fat appears greatest; however, supplementation with omega-3 fatty acids (a type of polysaturated fat) does not
appear to have an effect.
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. In addition, the review
suggested that a low-salt diet may be harmful in those with congestive heart
failure. However, the review was
criticized in particular for not excluding a trial in heart failure where
people had low-salt and -water levels due to diuretics. When this study is left out, the rest
of the trials show a trend to benefit. 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 happen
both through the increased blood pressure and,
quite likely, through other mechanisms. Moderate
evidence was found that high salt intake increases cardiovascular mortality;
and some evidence was found for an increase in overall mortality, strokes, and left ventricular
hypertrophy.
Medication
Aspirin has
been found to be of only modest benefit in those at low risk of heart disease
as the risk of serious bleeding is almost equal to the benefit with respect to
cardiovascular problems. In those
at very low risk it is not recommended.
Statins are
effective in preventing further cardiovascular disease in people with a history
of cardiovascular disease. As the
event rate is higher in men than in women, the decrease in events is more
easily seen in men than women. In
those without cardiovascular disease but risk factors statins appear to also be
beneficial with a decrease in the risk of death and further heart disease. A United States guideline recommends
statins in those who have a 12% or greater risk of cardiovascular disease over
the next ten years.
The time course over which statins provide prevention against
death appears to be long, of the order of one year, which is much longer than
the duration of their effect on lipids. The
medications niacin, fibrates and CETP Inhibitors, while they may increase HDL cholesterol do
not affect the risk of cardiovascular disease in those who are already on
statins.
The use of vasoactive agents
for people with pulmonary hypertension with left heart disease or hypoxemic
lung diseases may cause harm and unnecessary expense.
Supplements
While a healthy diet is
beneficial, in general the effect of antioxidant supplementation
(vitamin E, vitamin C, etc.) or vitamins has not been shown to
protection against cardiovascular disease and in some cases may possibly result
in harm. Mineral supplements have
also not been found to be useful. 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. Magnesium supplementation
lowers high blood pressure in a dose dependent manner. Magnesium therapy is recommended for
patients with ventricular arrhythmia associated
with torsades de pointes who present with long QT syndrome as
well as for the treatment of patients with digoxin intoxication-induced
arrhythmias. Evidence to support omega-3 fatty acid supplementation is lacking.
Management
Cardiovascular disease is treatable with initial treatment
primarily focused on diet and lifestyle interventions.
Epidemiology
Cardiovascular
diseases deaths per million persons in 2012
Disability-adjusted
life year for cardiovascular diseases per 100,000 inhabitants in 2004
Cardiovascular diseases are the leading cause of death. In 2008,
30% of all global death is attributed to cardiovascular diseases. Death caused
by cardiovascular diseases are also higher in low- and middle-income countries
as over 80% of all global death caused by cardiovascular diseases occurred in
those countries. It is also estimated that by 2030, over 23 million people will
die from cardiovascular diseases each year.
It is estimated that 60% of the world's cardiovascular disease
burden will occur in the South Asian subcontinent despite only accounting for
20% of the world's population. This may be secondary to a combination of
genetic predisposition and environmental factors. Organizations such as the Indian Heart Association are working with the World Heart Federation to raise awareness about this issue.
Research
The first studies on cardiovascular health were performed in
year 1949 by Jerry Morris using
occupational health data and were published in year 1958. The causes, prevention, and/or
treatment of all forms of cardiovascular disease remain active fields of biomedical research,
with hundreds of scientific studies being published on a weekly basis.
A fairly recent emphasis is on the link between low-grade
inflammation that hallmarks atherosclerosis and its possible interventions. C-reactive protein is a common inflammatory marker that
has been found to be present in increased levels in patients who are at risk
for cardiovascular disease. Also osteoprotegerin, which is involved with regulation of
a key inflammatory transcription factor called NF-κB, has been found to be a risk factor of
cardiovascular disease and mortality.
Some areas currently being researched include the possible links
between infection with Chlamydophila pneumoniae (a major cause of pneumonia) and coronary artery disease. The Chlamydia link has become less plausible with
the absence of improvement after antibiotic use.
Several research also investigated the benefits of melatonin on
cardiovascular diseases prevention and cure. Melatonin is a pineal gland
secretion and it is shown to be able to lower total cholesterol,
very-low-density and low-density lipoprotein cholesterol levels in the blood
plasma of rats. Reduction of blood pressure is also observed when
pharmacological doses are applied. Thus, it is deemed to be a plausible
treatment for hypertension. However, further research needs to be conducted to
investigate the side-effects, optimal dosage, etc. before it can be licensed
for use.
Source : https://en.wikipedia.org/wiki/Cardiovascular_disease
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