Vascular system overview
The blood vascular system, also called the circulatory system, of the body is made up of arteries, veins, and capillaries (tiny blood vessels between arteries and veins that distribute oxygen-rich blood to the body). The heart is responsible for pumping blood through this network of blood vessels throughout the body.
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Another vascular system of the body is the lymph system. The lymph vessels carry lymphatic fluid (a clear, colorless fluid containing water and blood cells). The lymphatic system helps to protect and maintain the fluid environment of the body by filtering and draining lymph away from each region of the body.
Collectively, the blood and lymphatic systems are the transport systems of the body. They supply oxygen, nutrients, removal of waste products, fluid balance, as well as many other functions, to all organs and tissues of the body. Therefore, conditions that affect the vascular system may affect the organs supplied by a particular vascular network, such as the coronary arteries of the heart. A blockage in the coronary arteries of the heart may cause a heart attack.
What causes vascular conditions and diseases?
A vascular disease is a condition that affects the arteries and/or veins. Most often, vascular disease affects blood flow, either by blocking or weakening blood vessels, or by damaging the valves that are found in veins. Organs and other body structures may be damaged by vascular disease as a result of decreased or completely blocked blood flow.
There are many different causes of the various types of vascular conditions and diseases. However, coronary artery disease (heart attack), cerebrovascular disease (stroke), and peripheral arterial disease (loss of limb or use of limb) are some of the leading causes of illness and death in the U.S.
These three vascular disease conditions (heart attack, stroke, and peripheral vascular disease) can be associated with the same cause, atherosclerosis (a build-up of plaque, which is a deposit of fatty substances, cholesterol, cellular waste products, calcium, and fibrin in the inner lining of an artery), and are all linked to the same risk factors.
Atherosclerosis is a systemic, progressive, chronic vascular disease process that particularly affects the carotid arteries (major blood supply to the brain), coronary arteries (blood supply to the heart), and the peripheral arteries in the same manner.
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It is unknown exactly how atherosclerosis begins or what causes it. Atherosclerosis may start as early as childhood. However, the disease has the potential to progress rapidly. It is generally characterized by the accumulation of fatty deposits along the innermost layer of the arteries. If the disease process progresses, plaque formation may take place. This thickening narrows the arteries and can decrease blood flow or completely block the flow of blood to organs and other body tissues and structures.
The presence of atherosclerosis in any one of these areas is a strong indicator that there is also the presence of atherosclerosis in the arteries of other parts of the body. Just as atherosclerosis in the arteries of the heart can cause a heart attack, or atherosclerosis of the arteries to the brain can cause a stroke, so can atherosclerosis of the leg arteries cause a blockage. A blockage can obstruct blood flow, and potentially result in pain in the leg(s), ulcers or wounds that do not heal, and/or the need for amputation (surgical removal) of the foot or leg.
Therefore, management of risk factors should be optimized to control the progression of vascular disease conditions caused by atherosclerosis. Studies have shown that lifestyle changes have not only stopped but also reversed the progression of atherosclerosis.
Because vascular conditions and diseases may involve more than one of the body's systems at a time, many types of doctors treat vascular problems. Specialists in vascular medicine and/or surgery work closely with doctors in other specialties, such as internal medicine, interventional radiology, cardiology, and others to ensure comprehensive care of patients with vascular conditions.
What are the risk factors for vascular diseases?
Modifiable risk factors that are associated with all four major vascular conditions are:
Hyperlipidemia (high levels of fats in the blood, such as cholesterol and triglycerides)
High blood pressure
Lack of exercise
Diet high in saturated fat
A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases have different risk factors.
Although these risk factors increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop the disease and have no known risk factors. Knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.
How can risk factors be medically managed?
Medical management of vascular conditions most often includes management of modifiable risk factors, such as diabetes, hyperlipidemia, smoking, and high blood pressure. An overview of the management of these four risk factors is given below:
Diabetes alone, without the other risk factors, accelerates the rate of atherosclerosis formation.
Elevated blood glucose levels are associated with increased risk for heart disease and stroke. The American Diabetes Association (ADA) recommendations include maintaining blood glucose levels in the range of 70 mg/dl to 130 mg/dl before meals. The ADA also recommends a blood test called hemoglobin A1c, which averages blood glucose levels over a period of several months, to determine if glucose levels have been controlled. A hemoglobin A1c level of less than 7% is desired.
What is hemoglobin A1c?
Hemoglobin is a substance found inside red blood cells. It carries oxygen for transport to all the cells in the body. Hemoglobin can also attach itself to glucose.
When too much glucose stays in the bloodstream for an extended period of time, the glucose will attach itself to the hemoglobin inside the red blood cells. The more glucose there is in the blood stream, the more glucose will be attached to the hemoglobin. A hemoglobin A1c blood test will be able to determine the average glucose level over a period of two to three months. Elevated hemoglobin A1c levels are associated with increased risk for cardiovascular disease.
Your doctor will determine the appropriate medication and care for your specific condition. Diabetes may be managed with diet and exercise alone, or with medications, such as oral antihyperglycemic medications, and/or insulin.
Hyperlipidemia is high levels of fats in the blood, such as LDL cholesterol and triglycerides. Two main types of fats (lipids) are found in the blood, cholesterol and triglycerides (lipoproteins). Cholesterol is an essential component found in all human cell membranes. Triglycerides are necessary to help transfer energy from food into body cells.
High levels of low density lipoprotein (LDL) cholesterol are one of the causes of altered structure of the innermost layer of the artery's wall. Elevated LDL levels are associated with the formation of atherosclerotic plaque (fatty material that becomes hardened, blocking the artery and stopping blood flow).
Cholesterol levels may rise and fall based on the types of fat you eat, the amount of exercise you do, and your weight. Your doctor may advise you to make changes in your diet as well as suggest an exercise and weight reduction plan specific to your needs. In some cases, there may be a family history of elevated fats in the blood. Your health care provider will advise the best treatment for your particular condition.
Lipid (fat) lowering therapy may be recommended to help reduce the progression of atherosclerotic disease. The National Cholesterol Education Program III (NCEP-III) guidelines recommend a target goal of LDL cholesterol at less than 130 mg/dl. However, if you have a higher risk for heart disease, an LDL of below 100 is ideal. The optimal goal for your LDL cholesterol can depend on other risk factors. Your health care provider will consider your individual risk factors to help determine what is best for you. Recommendations for other types of fats in the blood include triglycerides less that 150 mg/dl and high density lipoproteins (HDL) greater than 40 mg/dl.
Your doctor may determine that you require a medication to maintain a specific cholesterol level in addition to dietary and exercise changes. There are several types of medications used to decrease cholesterol. Statins are a group of antihyperlipidemic medications, and include simvastatin (Zocor), atorvastatin (Lipitor), and pravastatin (Pravachol), among others. Studies have shown that certain statins can decrease the thickness of the carotid artery wall, increase the size of the lumen (opening) of the artery and reduce vascular inflammation thought to be a cause of atherosclerosis.
Because atherosclerosis may progress to the point of narrowing or blocking blood vessels, another type of medication may be used to prevent narrowing or blockage caused by blood clots. Antiplatelet medications (platelets are blood cells that stick together to prevent bleeding) may be used to decrease the "stickiness" of platelets and help prevent blood clots from forming inside blood vessels. Such medications include aspirin, clopidogrel (Plavix), or dipyridamole (Persantine).
Smoking has been shown to promote the acceleration of atherosclerotic disease and has been identified as one of the strongest risk factors in the development of peripheral artery disease. Smoking is related to a decreased rate of successful outcomes in vascular surgical interventions, an increased amputation rate, and an increased number of heart attacks and strokes. Smoking is also related to a decreased rate in survival of heart attack and stroke victims.
The effects of tobacco include:
Constriction of blood vessels (as blood vessels become smaller, the blood pressure is raised)
Increased carbon monoxide levels in the bloodstream, which impairs oxygen transport
Formation of blood clots due to platelet activation
Acceleration of the process of atherosclerosis
Increased risk of blockage in leg arteries (there is a 30% to 50% percent increase with smoking one-half pack per day)
Cause of heart attacks, strokes, and/or death
Decreased chance of successful surgical outcome
Greater risk for amputation
Smoking cessation has been shown to decrease the progression of the atherosclerotic process.
Current guidelines advise all smokers to quit. If you are unable to quit smoking, your doctor may refer you to a specialist. A specialist may recommend educational materials, behavior modification counseling, medications, and follow-up care. Cessation interventions may also include support groups or individual counseling, learning new coping skills, sessions with a specialist for a prescribed period of time, and/or nicotine replacement therapy. Specific instruction should be included if nicotine replacement therapy is started. Nonnicotine medications may also be used as an alternative or in addition to other therapies.
Steps to smoking cessation include:
Dispose of all cigarettes and ash trays before you quit
Seek family and friends for support
Avoid social situations that stimulate desire for smoking (drinking alcohol)
Ask your doctor for a referral to a specialist for smoking cessation
Most insurance plans cover medications and services for smoking cessation. In some states, Medicaid will also include coverage for medications.
In addition, weight gain has been shown to be minimal after one year of smoking cessation. The benefits of quitting smoking outweigh the effects of weight gain.
High blood pressure (hypertension)
High blood pressure affects the structure of the wall of the artery, accelerating the rate at which atherosclerosis develops.
According to the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health, high blood pressure for adults is defined as:
In the most current NHLBI guidelines for hypertension, a new blood pressure category was added called pre-hypertension:
The NHLBI guidelines define normal blood pressure as follows:
These numbers should be used as a guide only. A single elevated blood pressure measurement is not necessarily an indication of a problem. Your doctor will want to see multiple blood pressure measurements over several days or weeks before making a diagnosis of hypertension (high blood pressure) and initiating treatment. A person who normally runs a lower-than-usual blood pressure may be considered hypertensive with lower blood pressure measurements than 140/90.
Weight loss, regular physical exercise, and balanced diet has shown to be effective in lowering high blood pressure. A weight loss of about 5% of total body weight may lower the blood pressure and cause blood pressure medications to be more effective. According to the Physical Activity Guidelines for Americans, strong evidence shows that 150 minutes or 2 hours and 30 minutes per week of moderate-intensity aerobic physical activity, such as brisk walking, pushing a lawn mower, ballroom dancing, or water aerobics can help lower the risk of high blood pressure.
Blood pressure medications may be used to help control elevated blood pressure. Your doctor will prescribe the appropriate medication(s) for your situation. There are several types of medications which act in different ways to lower blood pressure.