Cardiovascular System Health Article

Role in human health

It is difficult to overestimate the role the cardiovascular system plays in human health, with literally every cell of every tissue dependent on its function for survival. The cardiovascular system is the way the body transports things to and from the body's cells. Oxygen, nutrients, and hormones are carried from the point these substances are made or brought into the body to the cells for their use. Cellular wastes are transported from the cells to the lungs, kidneys, or liver to be broken down or removed from the body. The circulatory system is also one of the transport systems (along with the lymph) for the immune cells responsible for protecting the body from disease.

Changes in the functioning of the circulatory system have far reaching effects. A defect of the circulatory system, heart disease, is the number one cause of death in humans. Some of the common names and medical terms for the symptoms of a malfunctioning cardiovascular system include

• chest pain (angina pectoris)
• shortness of breath (dyspnea)
• general tiredness (fatigue)
• swelling (edema)
• loss of consciousness (syncope)
• light-headedness (presyncope)
• palpitations (arrhythmia or extrasystoles)
• limb pain or tiredness (claudication)
• abnormal skin color (pallor, cyanosis, erythemia, necrosis)
• sores on skin (ulceration)
• collapse (shock)
• sudden changes in vision, strength, coordination, speech, or sensation

Common diseases and disorders

Diagnosing cardiovascular disease can be complicated because often more than one cardiovascular problem exists at the same time in the same person. Symptoms of one problem can mask symptoms of another. Sometimes the multiple problems have a common cause or one cardiovascular problem can be causing another. This can make diagnosis and treatment a difficult task.

High blood pressure

The most common cardiovascular disease is high blood pressure (hypertension), affecting one in four Americans (one in three black Americans). Blood pressure is measured in millimeters of mercury, based on how high the pressure in the arteries can raise a column of mercury above baseline using a blood pressure cuff. With a generally accepted normal of systolic to diastolic of 120/80, the disease is categorized into three stages. The systolic measurement, the diastolic measurement, or both can be elevated with hypertension.

Stage 1 disease is present with systolic measurements of 5.12–5.47 in (130–139 mm) Hg, stage 2 with6.29–7.04 in (160–179 mm) Hg, and stage 3 with 7.08 in (180 mm) Hg or higher. For diastolic measurements, stage 1 occurs from 3.54–3.89 in (90 to 99 mm) Hg, stage 2 with 3.93–4.29 in (100 to 109 mm) Hg, and stage 3 with measurements above 4.33 in (110 mm) Hg. Treatment decisions for hypertension take into account not only the measured blood pressure, but also the presence of other cardiovascular disease, hereditary risk factors, evidence of damage to internal organs, and lifestyle (stress, diet, exercise).

Primary hypertension is associated with a persistent increase in resistance of blood flow in the arterioles, the smaller branches off the arteries. The precise cause is unknown.

Heart disease

Some specific diseases of the heart include cardiomyopathy, congenital heart disease, heart valve defects, myocardial infarcation (heart attack), problems of the pericardium, and arrhythmias. If any of these diseases cause the heart to lose its ability to pump blood effectively, the patient is said to have heart failure. Because poor pumping ability often results in an accumulation of fluid in the tissues and lungs, it is often called congestive heart failure.

Cardiomyopathy is a disease of the heart muscle with multiple causes and is the number one reason people undergo heart transplants. Categorized by the type of muscle damage, there are three general types of cardiomyopathy: dilated, hypertrophic, and restrictive. Dilated cardiomyopathy refers to the enlargement of the heart that is a response to the overall myocardial weakness. Many problems can cause dilated cardiomyopathy, including viral infections, excessive alcohol intake, and myocarditis (inflammation of the heart).

Hypertrophic cardiomyopathy is an abnormal over-growth of the heart muscle. An inherited disease, the overgrown muscle blocks the movement of blood both into and out of the heart. The most common cause triggering hypertrophic cardiomyopathy is hypertension. Restrictive cardiomyopathy is due to a stiffening of the heart muscle that prevents it from fully relaxing during diastole. This problem is a symptom of other diseases such as hemochromatosis (a defect in iron use by the body) or amyloidosis (overproduction of antibodies by the bone marrow that cannot be broken down).

Congenital heart disease is caused by defects of the heart present at birth. Defects can be relatively mild and asymptomatic to severe and life-threatening. Some more common problems are abnormally formed blood vessels that block blood flow, malformed heart valves, incorrect connections between arteries, veins, and the heart, or defects in the atrial or ventricular septa. The most common congenital heart defect is a combination of four problems called the teralogy of Fallot. With this problem the ventricular septum is incomplete, there is an obstruction to blood flow beneath the pulmonary artery, the aorta is shifted rightward, and the right ventricular wall is thickened.

Any of the hearts valves can obstruct blood flow if they are too stiff (stenosis) or don't close properly and allow blood to leak (regurgitation). Valve problems can cause congestive heart failure or heart enlargement, which can lead to angina or heart arrhythmias. Causes of valve disease include congenital defects, calcium deposits, and infections, such as endocarditis (a bacterial infection of the endocardium, the lining of the heart). Severe valve problems can be treated by removal of the diseased valve and replacement with an artificial valve.

A myocardial infarction (heart attack) is death of heart tissue due to the sudden lack of blood flow from the coronary arteries. Doctors believe the most common cause of the blockage is a blood clot that formed at a rupture of an atherosclerotic plaque that has broken loose. The results of the heart attack are dependent on the amount of heart tissue that is damaged. With less than 10% of the heart affected, there is a reduction in the ability of the heart to pump blood, but a normal lifestyle can often be maintained. At 25%, enlargement of the heart and heart failure is a common result. If 40% or more of the heart is damaged, shock or death usually occurs.

Pericarditis is inflammation of the pericardium, usually caused by a viral infection. Although this disease can cause sharp, piercing chest pain, it is usually self-limiting and ordinarily does not lead to further problems. Pericardial effusion is a collection of fluid around the heart in the pericardial sac. If the fluid amount is great enough, it can reduce the heart's ability to expand and receive blood, reducing its efficiency. This condition is known as cardiac tamponade. A final condition of the pericardium is pericardial constriction, an abnormal inflexibility of the pericardial membrane. Some types of pericarditis often result in this problem. If the inflexible membrane causes heart failure, it can be removed surgically.

Arrhythmias are abnormal heartbeats. Very broadly, arrhythmias can be classified into four different types: conduction system abnormalities, abnormally slow, abnormally fast, and irregular. Conduction system abnormalities are seen using electrocardiography units and do not directly cause an outwardly altered heartbeat. An example is some heart blocks, where the electrical signal adopts alternative paths in the heart to avoid nonconductive tissue.

Slow heartbeat (brachycardia) is the most common cause for the implantation of a pacemaker and can be caused by problems with the autonomic nervous system, the SA node, or the conduction system. Abnormally fast heartbeats (tachychardia) can be atrial flutter, the presence of an extra, abnormal pathway for electrical conduction in the heart, or ventricular tachychardia (V tach). Some common irregular heartbeats include extra beats (extrasystoles) and atrial fibrillation, where the atria stop having effective contractions and beat chaotically at several hundred times per minute.