Researchers have found that heart attacks and heart failure are really the late complications of a whole chain of events termed the cardiovascular continuum. The cardiovascular continuum links various risk factors, like hypertension, high blood cholesterol, and being overweight, with different types of heart disease. Heart disease can become progressively more severe, and more debilitating, throughout a person's life. Heart disease that occurs later in the continuum, like atherosclerosis, heart tissue death, and heart failure, is difficult and sometimes impossible to reverse.

The significance of the cardiovascular continuum is its emphasis on prevention. By treating risk factors that occur early in the cardiovascular continuum, like hypertension, diabetes, high blood fat levels, and smoking, it may be possible to prevent or slow the development of heart disease and to prolong life. These risk factors are in themselves rarely life threatening, but because they are usually without symptoms, it's important to be tested for them and to treat them through lifestyle changes and drug treatment.

Developing rapidly and early, the heart is the first organ to function in the embryo, and it takes up most of the room in the fetus's midsection in the first few weeks of its life. During its initial stages of development, the fetal heart actually resembles those of other animals. In its tubelike, two-chambered phase, the fetal heart resembles that of a fish. In its three-chambered phase, the heart looks like that of a frog. As the atria and then the ventricles start to separate, the human heart resembles that of a turtle, which has a partial septum in its ventricle. The final, four-chambered design is common to mammals and birds. The four chambers allow low-pressure circulation to the lungs and high pressure circulation to the rest of the body.

The cardiovascular system, which consists primarily of the heart and the blood vessels, is the first organ system to develop in humans. It provides oxygen and nutrients to all the organs and tissues of your body.

Lungs The lungs have a double blood supply: the pulmonary circulation allows for gas exchange with the alveoli (air sacs), and the bronchial circulation supplies blood to the lung tissue. Blood from the bronchial circulation drains into the left side of your heart through the pulmonary arteries. The pulmonary circulation is a low-pressure, low-resistance system, made possible by the four-chambered heart.

Brain The human brain is very metabolically active and consumes a great deal of energy, so it requires a large and constant supply of blood. Although it comprises only 2% of total body weight, your brain utilizes 25% of total oxygen consumption and receives 20% of your body's blood supply. The brain is supplied with blood through two pairs of arteries: the internal carotids and the vertebrals.

Kidney Because the kidneys filter waste products from the blood, they are heavily vascularized and receive 20% of the heart's output. Blood is furnished to your kidneys via the largest artery in the body, the abdominal aorta, and returns from the kidneys in the ascending vena cava.

Liver The liver is the only major organ that doesn't receive its blood supply entirely from arteries branching off of the aorta. The hepatic artery, which provides about a third of the liver's blood supply, receives blood from the aorta. But the other two thirds of the liver's blood supply are brought to it by the portal vein, which brings blood containing oxygen and nutrients from the small intestine, to be processed by the liver.

Obesity in childhood lays the ground for heart and arterial disease. Studies have found that teenagers can develop well-established fatty streaks (the precursors to plaque) in their coronary artery walls, and that even children as young as 10 can have the artery-narrowing plaque that may lead to heart attacks and strokes. Children with high blood cholesterol are likely to remain at risk of elevated blood cholesterol as they grow older.

Risk factors increase the likelihood that you'll develop cardiovascular disease, and the more risk factors you have, the greater your chances of developing it. Fortunately, most of these risk factors are within your control, like high cholesterol and high blood pressure levels, being overweight, smoking, lack of exercise, overconsumption of alcohol, unmanaged diabetes, and stress. Factors you can't control include genetics and aging.

If they don't get the oxygen and glucose they require, your brain cells start to die in minutes. That's exactly what happens when someone has a stroke. Most strokes are ischemic strokes, usually caused by atherosclerosis. Fatty deposits form on the walls of the arteries, which stiffen and become narrower. The narrowed arteries can easily become blocked completely by blood clots, cutting off the brain's vital blood supply. Stroke is the number two leading cause of death worldwide, second only to heart disease.

Over time, LDL cholesterol can build up on the walls of the coronary arteries and form hard plaques, reducing blood supply to the heart. This stiffening and narrowing of the arteries is called atherosclerosis. Sometimes the surface of a plaque ruptures, releasing substances that make platelets stickier and encouraging clots to form on the surface of the plaque. The clot can block the flow of blood through the already-narrowed artery entirely. Without blood, heart muscle tissue starts to die in what's termed a "myocardial infarction" a heart attack.

Arrhythmias

Heart arrhythmias occur when the electrical impulses that coordinate the heartbeat don't function properly. For example, a scar from a heart attack may cause the electrical impulse to short circuit around it and veer from the normal electrical pathway. Arrhythmias may cause the heart to beat too quickly, too slowly, or irregularly.

Valve disease

People can have congenital heart valve disease (that is, they were born with it), or they can acquire it later in life. Congenital valve disease usually involves pulmonary or aortic valves that didn't form properly in the womb. Acquired heart valve disease usually involves the aortic or mitral valves, which, although normal at first, become defective or diseased over time. Some acquired or congenital conditions will remain asymptomatic throughout a person's lifetime. Others, though, may worsen, and if left untreated, can cause heart failure, blood clots, or even sudden death.

Coronary artery disease (CAD)—clogged coronary arteries—can cause angina when blood flow is restricted, or heart attack when flow is severely reduced or completely blocked. If CAD is suspected, the most common initial tests to be given are electrocardiograms (EKGs), chest X-rays, blood tests, and "stress tests". If initial tests confirm the presence of heart disease, then additional tests may be performed. These could include coronary angiograms, echocardiograms, PET scans, and myocardial perfusion scans.

If symptoms of atherosclerosis are severe or if a life-threatening blockage is present, aggressive measures may be taken to open up clogged vessels. In addition to angioplasty and coronary artery bypass graft (CABG) surgery, endarterectomy may be performed or thrombolytic therapy given. In endarterectomy, plaques are surgically removed from the walls of the affected artery using a scalpel. Thrombolytic therapy attempts to break up the clot by inserting a clot-dissolving drug into the artery at the point where it is blocked.

For many years fat cells were thought to be biologically inactive, but it turns out that fat is far from inert. Fat cells secrete numerous chemicals that have been implicated in diabetes, heart disease, high blood pressure, stroke, and other disorders and diseases, including some forms of cancer. Obese people have enormous fat cells, which are more metabolically active than normal-size fat cells and more likely to churn out harmful substances. "Apples," people who carry their fat in the abdomen, are more likely to have diabetes and heart disease than "pears," people who deposit weight on the hips and thighs.

To keep your blood vessels healthy and clear, prevention is the best medicine. Eat a diet low in saturated fats and high in fruits, vegetables, nuts, and whole grains. If you smoke, quit, and if you don't smoke, don't start. Have regular checkups and keep track of your cholesterol levels and blood pressure readings. Manage chronic conditions, like diabetes, that can damage blood vessels and cause heart disease if uncontrolled. Staying active is key: your body was made to move. Exercise not only reduces your risk of cardiovascular disease, it also reduces stress and helps prevent many other diseases, including cancer.

For most people, cardiovascular disease is the result of unhealthy lifestyle choices. Wiser choices can give you more vitality, more self-confidence, and a better quality, longer life.