uses a laser to create several dozen tiny channels
through the wall of the heart’s left ventricle to
improve the flow of BLOOD and oxygen to the
MYOCARDIUM(heart MUSCLE). The surgeon makes a
small “window” incision through the ribs to gain
access to the myocardium, and the HEARTcontin-
ues to beat during the surgery. The channels allow
blood to flow directly from the ventricle’s chamber
to the muscle tissue. Researchers do not know
why TMLR relieves angina pectoris, though
believe it allows oxygen to directly enter myocar-
dial cells and also encourages new blood vessels to
grow (collateral circulation). Cardiologists gener-
ally use TMLR only when other treatments for
angina have failed or are not feasible. Most people
stay in the hospital for three to seven days follow-
ing surgery and are able to return to their regular
activities, including work, in four to eight weeks.
See also CORONARY ARTERY BYPASS GRAFT(CABG);
SURGERY BENEFIT AND RISK ASSESSMENT.
triglycerides blood level The amount of the
fatty acid group, triglycerides, that is present in
the BLOODcirculation. Most of the body’s fats are
in the chemical form of triglycerides, which pro-
vide the body with energy. The cells draw triglyc-
erides from the blood to meet their immediate
energy needs. The body acquires triglycerides from
dietary sources as well as manufactures them.
During digestion the gastrointestinal tract extracts
triglycerides from dietary saturated fats such as are
abundant in meats. When the level of triglycerides
in the blood meets or exceeds the body’s needs,
the LIVERconverts excess CALORIESthat derive from
any dietary source into triglycerides. The body
stores excess triglycerides in fat cells, drawing
from these stored energy supplies when demand,
such as increased physical activity, exceeds the
triglycerides available in the blood circulation.
In general, blood triglyceride levels rise when
CHOLESTEROL BLOOD LEVELS, and particularly low-
density lipoprotein cholesterol (LDL-C), are ele-
vated. Blood triglyceride levels also tend to be
elevated in OBESITYand DIABETES. The role elevated
blood triglyceride levels play in CARDIOVASCULAR
DISEASE(CVD) remains unclear. The National Cho-
lesterol Education Program (NCEP), a consensus
group of health experts, has established healthy
and unhealthy levels of triglycerides in the blood
based on correlations between elevated levels and
cardiovascular conditions such as ATHEROSCLEROSIS,
CORONARY ARTERY DISEASE, (CAD), and PERIPHERAL
VASCULAR DISEASE(PVD), as people who have these
conditions typically have elevated blood triglyc-
erides as well.
Doctors recommend lifestyle modifications such
as reducing dietary saturated fat and ALCOHOLcon-
sumption, increased daily exercise, and WEIGHT LOSS
AND WEIGHT MANAGEMENTwhen triglyceride levels
are slightly elevated (marginal) and often prescribe
lipid-lowering medications when triglyceride levels
are high or very high. Some people have elevated
triglyceride blood levels and healthy cholesterol
blood levels. For them, doctors recommend vigi-
lance to maintain healthy cholesterol blood levels
and annual monitoring, along with lifestyle habits
that support overall cardiovascular health.TRIGLYCERIDE BLOOD LEVELS
(MILLIGRAMS PER DECILITER)
less than 150 mg/dL healthy
150 to 199 mg/dL marginal
200 to 499 mg/dL high
500 mg/dL or higher very highSee also CALORIE; DIET AND CARDIOVASCULAR
HEALTH; DIET AND HEALTH; HYPERLIPIDEMIA; MEDICATIONS
TO TREAT CARDIOVASCULAR DISEASE; NUTRIENTS.112 The Cardiovascular System