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.
Triglyceride is a fatty substance that is composed of three fatty acids. Each
of these acids is attached to a glycerol molecule. Like cholesterol,
triglyceride in the blood either comes from the diet or the liver. Also, like
cholesterol, triglyceride cannot dissolve and circulate in the blood without
combining with a lipoprotein. Thus, after a meal, the triglyceride and
cholesterol that are absorbed into the intestines are packaged into round
particles called chylomicrons before they are released into the blood
circulation.
A chylomicron is a collection of cholesterol and triglyceride that is
surrounded by a lipoprotein outer coat. (Chylomicrons contain 90% triglyceride
and 10% cholesterol.) There are special enzymes on the blood vessels that break
up the triglyceride inside the chylomicrons, releasing fatty acids in the
process. The fatty acids can either be used by the muscles as energy, or
absorbed by fat cells where they are incorporated again into triglyceride that
can be stored in the fat cells for future energy needs. The chylomicrons are
then removed from the circulation by the liver. The liver not only removes
triglyceride and chylomicrons from the blood, it also synthesizes and packages
triglyceride into VLDL (very low-density lipoprotein) particles and releases
them back into the blood circulation. Therefore, before breakfast after an
overnight fast, most of the triglyceride in the blood comes from the liver in
the form of VLDL particles. Like chylomicrons, VLDL particles contain mostly
triglyceride. Some of the VLDL particles lose triglyceride in the blood and
become cholesterol-rich LDL particles.
Do high triglyceride levels cause atherosclerosis?
Whether elevated triglyceride levels in the blood lead to atherosclerosis and
heart attacks is controversial. While most doctors now believe that an
abnormally high triglyceride level is a risk factor for atherosclerosis, it is
difficult to conclusively prove that elevated triglyceride by itself can cause
atherosclerosis. However, it is increasingly recognized that elevated
triglyceride is often associated with other conditions that increase the risk of
atherosclerosis, including obesity, low levels of HDL- cholesterol, insulin
resistance and poorly controlled diabetes mellitus, and small, dense LDL
cholesterol particles.
What are the causes of elevated triglyceride levels?
In some people, abnormally high triglyceride levels (hypertriglyceridemia)
are inherited. Examples of inherited hypertriglyceridemia disorders include
mixed hypertriglyceridemia, familial hypertriglyceridemia, and familial
dysbetalipoproteinemia.
Hypertrigleridemia can often be caused by non-genetic factors such as
obesity, excessive alcohol intake, diabetes mellitus, kidney disease, and
estrogen- containing medications such as birth control pills.
How can elevated blood triglyceride levels be treated?
The first step in treating hypertriglyceridemia is a low fat diet with a
limited amount of sweets, regular aerobic exercise, loss of excess weight,
reduction of alcohol consumption, and stopping cigarette smoking. In patients
with diabetes mellitus, meticulous control of elevated blood glucose is also
important.
When medications are necessary, fibrates (such as Lopid), nicotinic acid, and
statin medications can be used. Lopid not only decreases triglyceride levels but
also increases HDL cholesterol levels and LDL cholesterol particle size.
Nicotinic acid lowers triglyceride levels, increases HDL cholesterol levels and
the size of LDL cholesterol particles, as well as lowers the levels of Lp (a)
cholesterol. The statin drugs have been found effective in decreasing
triglyceride as well as LDL cholesterol levels and, to a lesser extent, in
elevating HDL cholesterol levels. A relatively new medicine, fenofibrate
(Tricor), shows promise as an effective agent in lowering serum triglyceride
levels as well as raising HDL levels, particularly in patients who have had
suboptimal responses to Lopid. In some patients, a combination of Lopid or
Tricor with adjunctive statin therapy (see below) may be prescribed. While this
combination is often effective in patients with complex lipid disorders, the
potential for side effects may be increased and such patients should be under
strict medical supervision.
Lipid altering medications are used in lowering blood levels of undesirable
lipids such as LDL cholesterol and triglycerides and increasing blood levels of
desirable lipids such as HDL cholesterol. Several classes of medications are
available in the United States, including HMG CoA reductase inhibitors
(statins), nicotinic acid, fibric acid derivatives, and medications that
decrease intestinal cholesterol absorption (bile acid sequestrants and
cholesterol absorption inhibitors). Some of these medications are primarily
useful in lowering LDL cholesterol, others in lowering triglycerides, and some
in elevating HDL cholesterol. Medications also can be combined to more
aggressively lower LDL, as well as in lowering LDL and increasing HDL at the
same time.
Lipid altering medications commonly used in the United States
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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