L

left ventricular ejection fraction (LVEF) The per-
cent of BLOODa full left ventricle pumps into the
AORTAwith each CARDIAC CYCLE. LVEF provides an
assessment of cardiovascular limitations resulting
from damage to the HEARTsuch as by MYOCARDIAL
INFARCTIONor HEART FAILURE. Normal LVEF is 55 per-
cent; LVEF below 35 percent indicates severe heart
failure. Because it is not possible to directly meas-
ure the volume of blood the left ventricle pumps,
cardiologists use indirect methods to calculate the
LVEF. Among these methods are ECHOCARDIOGRAM
with Doppler ULTRASOUND, radionuclide scans, and
MAGNETIC RESONANCE IMAGING(MRI), all of which
allow the cardiologist to mathematically determine
the volume of the ventricle and visualize the flow
of blood through the heart. LVEF is one method to
monitor the progression of a degenerative cardio-
vascular condition such as heart failure as a crite-
rion for HEART TRANSPLANTATION.
See also CARDIAC CAPACITY; CARDIAC OUTPUT.

lifestyle and cardiovascular health The vari-
ables of daily living and the effects they have on
the health of the HEARTand BLOODvessels. Health
experts estimate that lifestyle modifications alone
could eliminate 90 percent or more of acquired
CARDIOVASCULAR DISEASE(CVD). Given that 60 mil-
lion Americans currently have at least one form of
cardiovascular disease, the potential impact of
such a reduction on LIFE EXPECTANCY as well as
QUALITY OF LIFEis overwhelming. The three lifestyle
factors that most significantly influence cardiovas-
cular health are cigarette smoking, dietary habits,
and physical activity.

Cigarette Smoking

NICOTINE, the active ingredient in cigarette smoke,
is a potent vasoconstrictor and cardiovascular

stimulant. Before a smoker finishes the first

inhalation from a cigarette, nicotine is already

surging through the bloodstream. It causes blood

vessels throughout the body to stiffen and narrow,

raising BLOOD PRESSURE. It raises the HEART RATE,

further increasing blood pressure as well as the

heart’s workload. Simultaneously, other sub-

stances in cigarette smoke interfere with the

OXYGEN–CARBON DIOXIDE EXCHANGE in the LUNGS,

reducing the amount of oxygen the blood carries

into the blood circulation. As smoking continues

over time, nicotine causes physical changes in the

cells of the ARTERYwalls, reducing their ability to

contract and relax. Blood pressure elevation may

become permanent (HYPERTENSION), and the arter-

ies are more susceptible to ATHEROSCLEROTIC PLAQUE.

With SMOKING CESSATIONmuch of the arterial func-

tion returns. Hypertension may improve though

ATHEROSCLEROSIS, including CORONARY ARTERY DIS-

EASE(CAD) andPERIPHERAL VASCULAR DISEASE(PVD),

remains.

Dietary Habits

The foods and the quantities of them that a person

eats significantly influence blood levels of choles-

terol and triglycerides. A diet high in fruits, veg-

etables, and whole grain products provides a rich

source of vitamins, antioxidants, and fiber that

help regulate these lipids. This is important

because elevated blood lipids (HYPERLIPIDEMIA) form

the basis of atherosclerosis and the conditions that

result, notably hypertension, CAD, and PVD.

These nutrients also help the body tissues, includ-

ing those of the cardiovascular system, to function

efficiently. Nutritious eating further helps regulate

the body’s GLUCOSE–INSULIN balance, important

from a cardiovascular perspective because insulin

plays a key role in the kinds and amounts of cho-

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