Cardiovascular disease (CVD) causes one in four deaths in the U.S. At least one half of Americans have one or more of the major risk factors of developing CVD, which are high blood pressure, high cholesterol and smoking. The term CVD encompasses a wide range of diseases that affect the heart and blood vessels, including those in the brain and other parts of the body, such as:
Coronary Artery Disease (CAD): Narrowing or blockage of the heart’s major blood supply, the coronary arteries. This is the most common type of CVD, usually resulting in chest pain (angina) or a heart attack.
High blood pressure: Condition where elevated pressure causes damage to the inside wall of the arteries.
Congestive heart failure: Condition where the heart can’t pump blood efficiently because of weakness and loss of function of the heart muscle and valves.
Arrhythmia: Dysfunction of the electrical system of the heart. Not all arrhythmias are dangerous, but they can increase the risk of a stroke.
Stroke: Loss of blood flow from a blood clot or piece of atherosclerotic plaque that results in brain damage. Strokes can also be caused by a brain bleed, such as a ruptured aneurysm.
Peripheral artery disease: Blood vessels that are narrowed by plaque cause poor circulation in the extremities. It results in slow wound healing, discoloration of the skin, loss of hair and feeling of coldness.
Medical assessment of CVD risk includes total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), screening for high blood pressure and diabetes, family history of early CVD and smoking status.
The Role of Inflammation in CVD
An acute (short-lived) inflammatory response is a normal, natural process. The cells of the immune system go to a damaged area to promote healing. Once the problem is contained, the immune system returns to normal. Chronic inflammation occurs when this process doesn’t shut off.
It can be low-grade inflammation which affects the cardiovascular system, or generalized inflammation affecting the joints and other parts of the body. Chronic inflammation promotes atherosclerosis and high blood pressure by causing changes inside the wall of the blood vessels. High sensitivity C-reactive protein (HS-CRP) is a test that measures cardiovascular inflammation.
“Good” and “Bad” Cholesterol
Most people have heard of LDL and HDL because they are part of the standard lipid profile. What they don’t realize is that LDL and HDL are just two of several lipoproteins that shuttle cholesterol and other fats throughout the body. Cholesterol is a necessary precursor to all of the body’s hormones and cell membranes. A standard lipid profile includes LDL, HDL, triglycerides and non-HDL. The non-HDL category encompasses all atherogenic or plaque-causing particles.
These are not direct measurements, but rather are calculations which estimate the amount in the blood. LDL-P and apolipoprotein B are direct measurements of the total number of atherogenic particles. Studies have shown LDL-P to be more accurate for predicting heart disease risk than LDL. LDL and HDL vary in size and composition, which is something that the standard lipid profile doesn’t address.
Lipoprotein fractionation is a test that breaks down LDL and HDL into small, medium and large particles. It is important because small, but not large, LDL can enter into the wall of the blood vessels and form plaque. Large HDL are better at cleaning up cholesterol and storing it away than small HDL. Advanced cardiovascular testing can give insight as to whether your cholesterol numbers pose a significant health risk.
Oxidation of LDL and Atherosclerosis
The formation of plaque inside the blood vessels can narrow or even block them. This is also known as “hardening of the arteries” because the arteries literally become filled with calcium-containing plaque, which makes them hard. Plaque develops when LDL becomes oxidized (oxLDL). Oxidation is degradation of the protein and fats due to reactive oxygen species or “free radicals”. It is a similar process to what happens when meat is left out and it turns brown.
Free radicals occur naturally in the body, but also are a byproduct of smoking and toxin exposure. They are increased when the diet is high in processed foods and low in vegetables and fruit which contain antioxidants. The body can also produce antioxidants when it has the necessary precursors. Oxidative stress and inflammation affect the health of the blood vessels, starting a cascade of pro-inflammatory changes. CVD development is a cycle that promotes itself once instigated.
Heart disease is the cause of over 600,000 deaths each year. The development of CVD is multifactorial, not simply the amount of LDL and HDL. The particle number and size of LDL and HDL, along with other factors like cardiovascular inflammation, are better predictors of risk. Advanced cardiovascular testing goes beyond the lipid panel and is available through the reference laboratory.