Worldwide, over 17 million people die each year of cardiovascular diseases. This corresponds to 48% of all deaths from non-communicable diseases which also include cancer, respiratory diseases, and diabetes. Cardiovascular diseases are aggravated by epidemics of smoking, obesity and inactivity. Diseases of the heart are also the leading cause of death in the United States. Approximately one quarter of all U.S. deaths are attributable to cardiovascular disease. The Centers for Disease Control and Prevention (CDC) reported that there were 616,067 deaths from heart disease in 2007. The number of deaths decreased to 598,607 in 2009, but heart disease remained the leading cause of death, followed closely by 568,668 deaths from cancer (malignant neoplasms).
Cardiovascular disease (CVD) is an abnormal function of the heart or blood vessels. It can cause an increase in risk for heart attack, heart failure, sudden death, stroke and cardiac rhythm problems. The major risk factors associated with heart disease are smoking, inactivity, poor diet, and being overweight.
The Cardiovascular System
The main components of the cardiovascular system are the heart, arteries, capillaries and veins. The function of the heart is to pump blood through the arteries to the organs of the body. The arteries branch out into a network of capillaries that carry blood with nutrients to the cells and remove their waste products. The capillaries merge to form the veins that circulate the blood back to the heart.
The pulmonary artery carries blood from the heart to the lungs. The function of the lungs is to exchange gases. The carbon dioxide produced from carbohydrate and fat metabolism is carried in the bloodstream to the lungs where it is released to the atmosphere, and oxygen from the air is absorbed and stored in the hemoglobin of the red blood cells.
The aorta, which is the largest artery in the body, branches from the heart into the mesenteric and renal arteries that carry blood to the intestines and the kidneys, respectively. The blood in the capillaries of the intestines absorbs carbohydrates, proteins, and fats from the foods processed by the digestive system. Blood from the intestines goes to the liver via the hepatic portal vein. The liver removes toxins from the blood. In the liver, the ammonia produced from protein metabolism is combined with carbon dioxide to create urea. The blood from the liver flows back to the heart via the hepatic vein and the inferior vena cava. The kidneys remove nitrogen waste products from the blood. Uric acid from nucleic acid metabolism and urea from protein metabolism are filtered out by the kidneys and excreted in the urine. Blood from the kidneys goes through the renal vein, then to the inferior vena cava, and finally recirculates back to the heart.
Types of Cardiovascular Diseases
The terms "heart disease" and "cardiovascular disease" are often used interchangeably. Heart disease includes coronary artery disease, irregular heartbeat (arrhythmia), racing heartbeat (tachycardia), heart infections and congenital heart defects. Cardiovascular disease refers to conditions involving blocked, narrowed or stiffened blood vessels that can lead to chest pain (angina), heart attack, or stroke. Cardiovascular disease decreases the blood flow to the heart, brain or other parts of the body and may cause symptoms such as pain, numbness, weakness or coldness in the legs or arms.
Atherosclerosis or hardening of the arteries is one of the principal causes of cardiovascular disease. This condition occurs when cholesterol and other fatty substances build up in the inner walls of arteries forming hard structures called plaques. The buildup of plaques is gradual, slowly progressing, and cumulative. Over time, the plaques narrow the blood vessels and force the heart to work harder causing an increase in blood pressure (hypertension). When a soft plaque ruptures, the blood forms a clot (thrombus) around the plaque material, and the clot travels until it encounters a narrow blood vessel through which it cannot pass. The clot may partially obstruct or completely stop blood flow causing oxygen starvation in the tissues normally irrigated by the blood vessel.
A heart attack, also called a myocardial infarction, occurs when a coronary artery gets blocked. A coronary artery is a blood vessel that supplies blood to a part of the heart muscle; the blockage is called a coronary thrombosis. Blockage of an artery to the brain causes an ischemic stroke. The cells of the brain tissue die within a few minutes after a stroke and can result in paralysis or speech impediments. Aneurysms are bulges and weakened sections of the blood vessels that can occur anywhere in the body. The bursting of an aneurysm causes internal bleeding that can have life-threatening consequences. A hemorrhagic stroke occurs when a weakened blood vessel ruptures inside the brain.
Heart failure, peripheral artery disease and cardiac arrest are other common complications of heart disease. Heart failure occurs when the muscles of the heart weaken and the heart cannot pump enough blood to meet the body's needs. Peripheral artery disease is a condition where the limbs, usually the legs do not receive enough blood flow. This causes leg pain when walking (claudication). Cardiac arrest is the sudden and unexpected loss of heart function, breathing and consciousness. This is usually caused by an electrical disturbance in the heart that disrupts its pumping action.
Risk factors for cardiovascular disease
In epidemiology, a risk factor is a variable associated with an increased risk of disease. Some risk factors, such as sex, age or family cannot be reduced, whereas the risk posed by smoking and poor diet can be eliminated by lifestyle changes.
The best preventive measures to avoid cardiovascular disease consist of avoiding bad habits like smoking. Smoking introduces a lot of noxious chemicals into the body and causes the deterioration of tissues. Long-term smokers frequently develop cancer or chronic obstructive pulmonary disease (COPD). Cardiovascular diseases can also be prevented by regularly eating a healthy diet that is high in fiber and low in saturated fat. Diets high in fibers from vegetables and nuts and low in saturated fat help to maintain normal cholesterol levels and avoid plaque formation in the blood vessels. Elimination of hydrogenated fats from the diet also helps to promote good blood lipid profiles.
Being overweight contributes to the development of diabetes and high blood pressure which are risk factors for cardiovascular disease. It is advisable to maintain a body weight with a Body Mass Index between 18.5 and 24.9. The number of calories consumed can be reduced substantially by eliminating sugary drinks and cutting out cakes, doughnuts, ice cream, and other desserts. (Use the diet calculator) Avoid high blood pressure by exercising regularly for 30 minutes per day, by not exceeding the upper limit of 2.3 grams of sodium per day, and by managing stress. Practicing good hygiene helps to prevent infectious diseases that can also affect heart health. (Learn about hygiene).