By the middle of the 20th century, cardiovascular disease was the leading cause of death in northern Europe. Coronary artery disease was the primary cause, although rheumatic fever and high blood pressure also claimed lives. The number of deaths caused by cardiovascular disease peaked by the early 1980s, and over the last 25–35 years preventive treatments have brought about a steady decline in cardiovascular disease deaths in many developed countries.
This section covers the major disorders affecting the heart and the circulation. The first articles overlap to a certain extent because some cardiovascular disorders can lead to the development of others. Smoking, an unhealthy diet, being overweight, and lack of exercise are risk factors for the development of hypertension (high blood pressure) and atherosclerosis, in which the arteries are narrowed. Narrowing of the coronary arteries that supply the heart muscle can cause coronary artery disease, which itself is the major cause of angina and heart attacks. If the heart is damaged by coronary artery disease or a heart attack, it may be unable to pump blood efficiently around the rest of the body, resulting in heart failure. Heart failure can develop suddenly, or it may be a chronic disorder that develops over a number of years.
The last articles in the section cover hypotension, the medical term for low blood pressure, and shock. Shock is a medical emergency that requires immediate treatment in hospital.
For further information on the structure of the cardiovascular system, see Blood Flow Through the Heart.
Disorders of heart rate and rhythm are caused by disturbances in the heart’s electrical system and are very common, particularly in elderly people. These disorders do not always cause symptoms and are sometimes detected only during routine health checkups. Treatment usually consists of drugs, although newer techniques that use carefully controlled electric currents are also used.
A healthy adult has a resting heart rate of 60–80 beats per minute, although this rate rises during exercise. Children have a higher resting heart rate, while that of very fit adults and the elderly may be as low as 50 beats per minute. Disorders that affect the pumping action of the heart may increase or decrease the heart rate, alter its rhythm, or, in cardiac arrest, stop the heart pumping altogether. Many of these disorders have coronary artery disease or heart failure as an underlying cause. The first article in this section describes ectopic beats, which are extra, isolated heartbeats. This article is followed by an overview of arrhythmias, which are abnormal heart rates and rhythms, and a discussion of individual types of arrhythmias. The final article discusses cardiac arrest, which is the sudden and complete failure of the heart to pump blood caused by a disturbance in its electrical system. Cardiac arrest is a potentially fatal condition and requires emergency medical treatment.
For more information on the structure and function of the heart, see Blood Flow Through the Heart.
Healthy heart valves and muscle are essential for the heart to pump blood efficiently. Heart valve disorders are less common today in the UK than in the past because a major cause, rheumatic fever, is now rare. Heart muscle disorders often used to be fatal but have a better outlook now because of improved treatments.
The first articles in this section cover heart valve disorders. Blood is pumped around the body at very high pressure by the left side of the heart. The valves on this side, called the aortic and mitral valves, are therefore the ones most often affected by disorders. If a heart valve does not work properly, blood cannot circulate efficiently, and the heart has to pump harder or faster in order to compensate. The next articles discuss disorders of the heart muscle and the lining of the heart (the endocardium). Any disorder that affects the heart muscle reduces the heart’s efficiency and may eventually be fatal. The last article discusses rheumatic fever, a disorder that may damage the heart valves after many years.
Other disorders of the heart muscle, such as heart attack and heart failure, are discussed elsewhere in the guide (see Major cardiovascular disorders). Congenital heart disease is covered in the section on infancy and childhood.
For more information on the structure and function of the heart valves and muscle, see Blood Flow Through the Heart.
The peripheral blood vessels carry blood from the heart to the rest of the body and back to the heart, providing oxygen and nutrients to all parts of the body. If the blood vessels are diseased, oxygen supply to the tissues is reduced, leading to possible tissue damage and even tissue death. Many peripheral vascular disorders are more common in people who smoke and have a high-fat diet.
All of the blood vessels that carry blood around the body, apart from those in the heart and the brain, are known collectively as the peripheral vascular system. The peripheral vascular system consists of arteries, which carry blood away from the heart, and veins, which carry blood towards the heart.
This section begins by discussing aortic aneurysm, which is a potentially life-threatening disorder of the largest artery in the body. The second article examines thrombosis and embolism, in which a peripheral artery or vein becomes blocked. The most common cause of these disorders is a build-up of fatty deposits on the artery walls, which is a factor that also contributes to the development of diabetic vascular disease. All of these disorders reduce blood supply to the tissues, leading to conditions such as lower limb ischaemia and gangrene. Disorders that affect the small blood vessels in the hands and feet are then considered.
The section ends with a discussion of disorders of the peripheral veins. The veins may be blocked by a blood clot, as occurs in deep vein thrombosis and superficial thrombophlebitis, or may develop structural abnormalities, as occurs in varicose veins.
For more information on the structure and function of arteries and veins, see Blood Flow Through the Heart.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.