Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
HDL is the good cholesterol because it protects the arteries from the
atherosclerosis process. HDL cholesterol extracts cholesterol particles from the
artery walls and transports them to the liver to be disposed through the bile.
It also interferes with the accumulation of LDL cholesterol particles in the
artery walls.
The risk of atherosclerosis and heart attacks in both men and is strongly
related to HDL cholesterol levels. Low levels of HDL cholesterol are linked to a
higher risk, whereas high HDL cholesterol levels are associated with a lower
risk.
Very low and very high HDL cholesterol levels can run in families. Families
with low HDL cholesterol levels have a higher incidence of heart attacks than
the general population, while families with high HDL cholesterol levels tend to
live longer with a lower frequency of heart attacks.
Like LDL cholesterol, life style factors and other conditions influence HDL
cholesterol levels. HDL cholesterol levels are lower in persons who smoke
cigarettes, eat a lot of sweets, are overweight and inactive, and in patients
with type II diabetes mellitus.
HDL cholesterol is higher in people who are lean, exercise regularly, and do
not smoke cigarettes. Estrogen increases a person's HDL cholesterol, which
explains why women generally have higher HDL levels than men do.
For individuals with low HDL cholesterol levels, a high total or LDL
cholesterol blood level further increases the incidence of atherosclerosis and
heart attacks. Therefore, the combination of high levels of total and LDL
cholesterol with low levels of HDL cholesterol is undesirable whereas the
combination of low levels of total and LDL cholesterol and high levels of HDL
cholesterol is favorable.
What are LDL/HDL and total/HDL ratios?
The total cholesterol to HDL cholesterol ratio (total chol/HDL) is a number
that is helpful in estimating the risk of developing atherosclerosis. The number
is obtained by dividing total cholesterol by HDL cholesterol. (High ratios
indicate a higher risk of heart attacks, whereas low ratios indicate a lower
risk).
High total cholesterol and low HDL cholesterol increases the ratio and is
undesirable. Conversely, high HDL cholesterol and low total cholesterol lowers
the ratio and is desirable. An average ratio would be about 4.5. Ideally, one
should strive for ratios of 2 or 3 (less than 4).
What are the treatment guidelines for low HDL cholesterol?
In clinical trials involving lowering LDL cholesterol, scientists also
studied the effect of HDL cholesterol on atherosclerosis and heart attack rates.
They found that even small increases in HDL cholesterol could reduce the
frequency of heart attacks. For each 1 mg/dl increase in HDL cholesterol, there
is a 2 to 4% reduction in the risk of coronary heart disease. Although there are
no formal NCEP (please see discussion above) target treatment levels of HDL
cholesterol, an HDL level of <40 mg/dl is considered undesirable and measures
should be taken to increase it.
How can levels of HDL cholesterol be raised?
The first step in increasing HDL cholesterol levels (and decreasing LDL/HDL
ratios) is therapeutic life style changes. When these modifications are
insufficient, medications are used. In prescribing medications or medication
combinations, doctors have to take into account medication side effects as well
as the presence or absence of other abnormalities in cholesterol profiles.
Regular aerobic exercise, loss of excess weight (fat), and cessation of
smoking cigarettes will increase HDL cholesterol levels. Regular alcohol
consumption (such as one drink a day) will also raise HDL cholesterol. Because
of other adverse health consequences of excessive alcohol consumption, alcohol
is not recommended as a standard treatment for low HDL cholesterol.
Medications that are effective in increasing HDL cholesterol include
nicotinic acid (niacin), gemfibrozil (Lopid), estrogen, and to a much lesser
extent, the statin drugs (discussed below). A newer medicine, fenofibrate
(Tricor) has shown much promise in selectively increasing HDL levels and
reducing serum triglycerides.
Angina is chest pain that is due to an inadequate supply of oxygen to the heart muscle.
Angina can be caused by coronary artery disease or spasm of the coronary
arteries. EKG, exercise treadmill, stress echocardiography, stress thallium, and cardiac
catheterization are important tests used in the diagnosis of angina.
Cholesterol is naturally produced by the body, and is a building block for cell membranes and hormones. Low-density lipoprotein (LDL) cholesterol is the "bad" cholesterol, conversely, high-density lipoprotein (HDL) cholesterol is the "good" cholesterol. High cholesterol treatment includes lifestyle changes (diet and exercise), and medications such as statins, bile acid resins, and fibric acid derivatives.
Heart attack happens when a blood clot completely obstructs a coronary
artery supplying blood to the heart muscle. A heart attack can cause chest pain, heart failure, and electrical
instability of the heart.
Rhabdomyolysis is a rapid deterioration and destruction of skeletal muscle. Some of the causes of rhabdomyolysis include severe burns, muscle trauma, coma, seizures, electrolyte imbalance, medications (statins), viruses, bacteria. Treatment of rhabdomyolysis depends on the cause.
Peripheral vascular disease (PVD) refers to diseases of the blood vessels (arteries and veins) located outside the heart and brain. While there are many causes of peripheral vascular disease, doctors commonly use the term peripheral vascular disease to refer to peripheral artery disease (peripheral arterial disease, PAD), a condition that develops when the arteries that supply blood to the internal organs, arms, and legs become completely or partially blocked as a result of atherosclerosis. Peripheral artery disease symptoms include: intermittent claudication, rest pain, numbness in the extremities, and more. Treatment for peripheral artery disease include: lifestyle measures, medication, angioplasty, and surgery.
When a portion of the brain loses blood supply, through a blood clot or embolus, a transient ischemic attack (TIA, mini-stroke) may occur. If the symptoms do not resolve, a stroke most likely has occurred. Symptoms of TIA include: confusion, weakness, lethargy, and loss of function to one side of the body. Risk factors for TIA include vascular disease, smoking, high blood pressure, high cholesterol, and diabetes. Treatment depends upon the severity of the TIA, and whether it resolves.
Heart attacks are the major causes of unexpected, sudden death among men and women. A heart attack is also a significant cause of heart failure. Learn the risk factors for heart attack such as high blood pressure, diabetes, and other heart conditions. Lowering your risk factor, lifestyle changes, and in some cases medication are the most effective way of preventing a heart attack.
A heart attack is a layperson's term for a sudden blockage of a coronary artery. This photo essay inlcudes graphics, pictures, and illustrations of diseased heart tissue and the mechanisms that lead to coronary artery disease, and possible heart attack.
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