cardiovascular disease

Cardiovascular disease refers to the class of diseases that involve the heart and/or blood vessels (arteries and veins). While the term technically refers to any disease that affects the cardiovascular system, it is usually used to refer to those related to atherosclerosis (arterial disease). These conditions have similar causes, mechanisms, and treatments.

Over 50 million Americans have cardiovascular problems, and most other Western countries face high and increasing rates of cardiovascular disease. It is the number 1 cause of death and disability in the United States and most European countries. By the time that heart problems are detected, the underlying cause (atherosclerosis) is usually quite advanced, having progressed for decades. There is therefore increased emphasis on preventing atherosclerosis by modifying risk factors, such as healthy eating, exercise and avoidance of smoking.

Forms

Cardiovascular disease usually occurs as a result of arterial damage. The symptoms and treatments depend on which set (or sets) of arteries are affected.

In coronary heart disease, atherosclerotic plaques (inflamed fatty deposits in the blood vessel wall) obstruct the coronary arteries (blood vessels supplying the heart). Narrowing of arteries is called arterial stenosis. When the blockages become severe enough, the blood flow to the heart is restricted (cardiac ischemia), especially during increased demand (i.e. during exertion or emotion). This results in angina pectoris. The acute stage of coronary heart disease occurs when one of the plaques ruptures, forming a thrombus (blood clot) that acutely occludes the whole artery. The portion of the heart muscle supplied by that artery dies; this is known as a myocardial infarction (or a heart attack in lay parlance). This may result in the death of the patient if the affected area is large enough. If the patient survives, congestive heart failure may result.

Similarly, inflammation and blood clots may obstruct the cerebral arteries (those supplying the brain). As the disease progresses, an artery may be transiently blocked, causing cerebral ischemia. This results in a transient ischemic attack (TIA), called a mini-stroke in lay parlance. If the obstruction is severe, a cerebrovascular accident, or stroke may result, due to the death of brain tissue supplied by the artery.

In peripheral artery disease, obstruction occurs in the arteries of the arms or legs. This results initially in pain, during temporary obstruction, and finally in tissue death and gangrene if not treated.

There are many specific illnesses that may occur in association with these and other cardiovascular disease. In addition to the ones mentioned above, these include hypertension (high blood pressure), arterial aneurysms (arterial enlargement and weakening), cardiomegaly (abnormal enlargement of the heart), tachycardia/bradycardia/arrhythmia (fast/slow/irregular heart rates), cardiac arrest (heart stoppage), cardiomyopathy (heart muscle weakness), heart valve regurgitation (leakage), and heart valve stenosis (narrowing).

Risk factors

There are many risk factors which predispose to various forms of cardiovascular disease. These include the following:

• Age
• Absence of key nutritional elements, such as polyphenol antioxidants
• Diabetes mellitus
• Hypercholesterolemia (elevated cholesterol levels) and less than excellent lipoprotein particle profile (cholesterol subtypes)
• Tobacco smoking
• Higher fibrinogen and PAI-1 blood concentrations
• Elevated homocysteine, or even upper half of normal
• Elevated blood levels of asymmetric dimethylarginine
• High blood pressure
• Exposure to high levels of environmental noise
• Obesity, especially central or male-type obesity; apart from being linked to diabetes, this form of obesity independently increases cardiovascular risk, presumedly by inducing an inflammatory and procoagulant state
• Genetic factors/Family history of cardiovascular disease
• Physical inactivity
• Being male

Although men have a higher rate of cardiovascular disease than women, it is also the number one health problem for women in industrialized countries. After menopause, the risk for women approaches that of men. Hormone replacement therapy alleviates a number of post-menopausal problems, but appears to increase the risk of cardiovascular disease.

Prevention

Attempts to prevent cardiovascular disease take the form of modifying risk factors. Some, such as gender (male or female), age, and family history, cannot be modified. Smoking cessation (or abstinence) is one of the most effective and easily modifiable changes. Regular cardiovascular exercise (aerobic exercise) complements the healthful eating habits. Sometimes, the combination of diet and exercise will improve lipoprotein (cholesterol) levels; if not, a physician may prescribe "cholesterol-lowering" drugs, such as the statins. These medications have additional protective benefits aside from their lipoprotein profile improvement. Aspirin may also be prescribed, as it has been shown to decrease the clot formation that may lead to myocardial infarctions and strokes; it is routinely prescribed for patients with one or more cardiovascular risk factors.

Eating oily fish at least twice a week may help reduce the risk of sudden death and arrhythmias. Olive oil is said to have the greatest benefits. Studies of individual heart cells showed that the fatty acids blocked excessive sodium and calcium currents in the heart, which could otherwise cause dangerous, unpredictable changes in its rhythm (Leaf et al 2003).

See also Diet and Heart Disease.

Treatment

Treatment of cardiovascular disease depends on the specific form of the disease in each patient, but effective treatment always includes preventative lifestyle changes discussed above. Medications, such as blood pressure reducing medications, aspirin and the statin cholesterol-lowering drugs may be helpful.. In some circumstances, surgery or angioplasty may be warranted to reopen, repair, or replace damaged blood vessels.

Research

The causes, prevention, and/or treatment of all forms of cardiovascular disease are 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 (CRP) is an inflammatory marker that may be present in increased levels in the blood in patients at risk for cardiovascular disease. Its exact role in predicting disease is the subject of debate.

Some areas currently being researched include possible links between infection with Chlamydia pneumoniae and coronary artery disease. The Chlamydia link has become less plausible with the absence of improvement after antibiotic use (Andraws et al 2005).

References

• Andraws R, Berger JS, Brown DL. Effects of antibiotic therapy on outcomes of patients with coronary artery disease. JAMA 2005;293:2641-7. PMID 15928286.
• Leaf A, Kang JX, Xiao YF, Billman GE. Clinical prevention of sudden cardiac death by n-3 polyunsaturated fatty acids and mechanism of prevention of arrhythmias by n-3 fish oils. Circulation 2003;107:2646-52. PMID 12782616.

External links

• Heart disease 'costing UK £29bn' at BBC News, 14 May 2006
• Diet, Nutrition and the prevention of chronic diseases (including cardiovascular diseases) by a Joint WHO/FAO Expert consultation (2003). Summary by GreenFacts.