Cardiovascular Disease
Cardiovascular disease (CVD) is an umbrella term used to describe any abnormal condition characterized by dysfunction of the heart and blood vessels (including arteries and veins).
The most common cardiovascular diseases in the United States include
• Coronary heart disease (including myocardial infarction or heart attack, and angina pectoris, or chest pain)
• Stroke
• Heart failure
Most cardiovascular diseases are associated with atherosclerosis, a slow and progressive process in which arteries narrow and harden. During atherosclerosis, excess amounts of fat, cholesterol, calcium, and other substances build up beneath the cells that line artery walls and contribute to the formation of plaque. Over time, as plaque builds up, it narrows the opening of blood vessels, limiting the amount of oxygen-rich blood and nutrients that can flow to the heat or the brain. When blood flow to the heart is blocked, a heart attack occurs; when blood flow to the brain is blocked, a stroke occurs. Harmful blood clots can also break off and block a vessel.
Although they’re much less common, some forms of cardiovascular disease are caused by abnormal heart rhythm or heart valve function, or infection or toxins that make it harder for the heart to pump blood (as in cariomyopathy).
Cardiovascular disease (including high blood pressure) affects an estimated 81 million people in the United States. It is the leading cause of death and a major cause of disability among both men and women in the Unties States; it causes an estimated 700,000 deaths each year.
Although specific genes contribute to the development of some forms of cardiovascular disease (including congenital heart disease, an inherited condition present at birth), most often genetic tendencies (including family history), environment, and individual lifestyle factors interact and contribute to the development of cardiovascular diseases. Key risk factors for cardiovascular disease include
• High blood pressure
• Overweight and obesity
• High total or LDL cholesterol
• Low HDL cholesterol
• High triglycerides
• Diabetes
• Smoking
• Physical inactivity
How to Interpret Blood Values
A simple blood test taken after 9- to 12-hour fast can reveal your total, LDL, and HDL cholesterol and triglyceride levels.
Because cholesterol and triglycerides cannot dissolve in blood, they are carried in the blood and throughout the body by lipoproteins. The three main types of lipoproteins are as follows:
• Low-density lipoprotein (LDL)
• Very low-density lipoprotein (VLDL)
• High-density lipoprotein (HDL)
LDL cholesterol makes up most of the cholesterol found in the blood. It is known as “bad” cholesterol because high levels indicate an unhealthy buildup of cholesterol in the arteries; the more LDL in the blood, the greater the risk for heart disease. Too much saturated fat, trans fats, and (to a lesser extent) dietary cholesterol can contribute to high LDL levels.
HDL cholesterol, also known as “good cholesterol”, carries cholesterol from other parts of the body back to the liver; the liver is in charge of moving “bad” LDL cholesterol out of the body. Having low HDL cholesterol levels increases the risk of cardiovascular disease. Consuming too little dietary fat (less than 15 percent of total calories), having high triglycerides, being overweight or obese, and having hyperglycemia or diabetes all contribute to low HDL levels.
Almost all the lipids found in foods and in our bodies are in the form of triglycerides (made up of a molecule of glycerol attached to three fatty acids). Having a high triglyceride level increases the risk of cardiovascular diseases. Uncontrolled diabetes, kidney or thyroid problems, or a diet that’s low in protein and high in refined carbohydrates or alcohol can contribute to high triglyceride levels.
Some experts recommend using a ratio of total cholesterol to HDL cholesterol to estimate risk of cardiovascular disease. The goal is to keep your ratio below 5:1, but 3.5:1 is considered desirable. The National Cholesterol Education Program (NCEP) recommends that the following children be screened for high cholesterol starting at age 2 but no later than age 10:
• Those with a parent whose total cholesterol level is > 240 mg/dL
• Those with a family history of cardiovascular disease before age 55 in men and 65 in women
• Those who are overweight or obese or have diabetes, high blood pressure, or other risk factors
Children with “acceptable” cholesterol levels should be rechecked in 3-5 years; those with “borderline” levels should have their levels rechecked in 1 year.
Two other measurements that can be useful in determining a person’s cardiovascular risk include C-reactive protein (CRP) and homocysteine.
C-reactive protein is one of the proteins release by the body in response to an injury, an infection, or anything that causes inflammation. There’s evidence that high CRP levels predict future heart attacks or other cardiovascular events. A blood test called a high sensitivity C-reactie protein (hsCRP) assay is currently available. This test is used with people who have already suffered from a cardiovascular “event” (e.g., heart attack, stroke) to predict their risk for additional events or in those at high risk for them. If after consulting with a doctor you decide to have your hsCRP measured, what your values indicate:
• hsCRP < 1.0 mg/L – Low risk for cardiocascualr disease • hsCRP between 1.0 and 3.0 mg/L – Average risk for cardiovascular disease • hsCRP > 3.0 mg/L – High risk of cardiovascular disease
it’s important to note that those with autoimmune diseases, cancer, or other infectious diseases can have falsely elevated hsCRP levels.
Homocysteine is an amino acid that may provide you with a glimpse of your future risk for cardiovascular disease. Recent research has linked high homocysteine levels to a greater incidence of stroke and chronic heart failure, increased death from cardiovascular disease and other adverse diseases and conditions. Although population-wide testing of homocysteine levels is not currently recommended by the American Heart Association (AHA), many researchers and practitioners believe it can be quite useful for those at high risk for cardiovascular disease; discuss it with your physician.
