approaches, which must include lifestyle modifica-
tions to be successful, often can slow its progress.
Risk Factors and Preventive MeasuresThe risk factors for PVD include smoking, other
atherosclerotic disease processes such as CAD, dia-
betes, and HYPERLIPIDEMIA. Controlling or eliminat-
ing these factors reduces the risk for PVD. Once
PVD shows symptoms, then the most effective
approach is aggressive management to prevent the
condition from worsening.
See alsoATRIAL FIBRILLATION; CARDIOVASCULAR DIS-
EASE PREVENTION; DEEP VEIN THROMBOSIS(DVT); WALK-
ING FOR FITNESS.
physical exercise and cardiovascular health
The influence of regular physical activity on the
structures and functions of the cardiovascular sys-
tem. Regular AEROBIC EXERCISE has numerous
effects on the cardiovascular system, improving
the heart’s pumping efficiency as well as the circu-
lation’s oxygen transport to the tissues of the
body. It also improves the efficiency with which
cells throughout the body, and notably those of
skeletal MUSCLE, use oxygen. This decreases
demand on the HEART, generally slowing the HEART
RATEand decreasing BLOOD PRESSURE. As well, phys-
ical activity increases INSULIN sensitivity, which
helps the body maintain a healthy BLOODlipid bal-
ance to reduce the risk for HYPERLIPIDEMIA.
PHYSICAL EXERCISE RECOMMENDATIONS- 30 to 45 minutes of moderate physical activity
five to seven days a week - 20 to 45 minutes of vigorous physical exercise
three to four days a week
Health experts consider physical inactivity to be
the prime lifestyle factor contributing to most
acquired CARDIOVASCULAR DISEASE(CVD). Though rec-
ommendations call for 30 minutes of moderate
physical exercise daily and 30 to 45 minutes of vig-
orous aerobic exercise three to four times a week,
fewer than 20 percent of American adults are phys-
ically active at these levels and about 20 percent get
no physical exercise at all. Health experts attribute
at least 250,000 of deaths from cardiovascular dis-
ease to physical inactivity. Yet the level of physical
activity that could prevent these deaths is minimal,
only 30 minutes a day of moderately brisk walking
(a pace of 3 to 4 miles per hour).
Small amounts of moderately intense physical
activity that accumulate to the recommended
exercise times are equally effective as contiguous
blocks of exercise time, an important finding to
emerge from recent research into the relationship
between physical activity and cardiovascular
health. Meeting the recommended minimum
activity levels could prevent as much as 40 per-
cent of cardiovascular disease. Ideal activities for
cardiovascular health include walking, bicycling,
running, and swimming.
See alsoAEROBIC FITNESS; CARDIOVASCULAR DISEASE
PREVENTION; DIET AND CARDIOVASCULAR HEALTH; DIET
AND HEALTH; EXERCISE AND HEALTH; LIFESTYLE AND CAR-
DIOVASCULAR HEALTH; WALKING FOR FITNESS.premature ventricular contraction (PVC) An
early heartbeat that causes the sensation of a
skipped beat. Most often PVCs are harmless. They
may occur spontaneously, without apparent
cause, and are most noticeable at rest or following
strenuous exercise. CAFFEINE, pseudoephedrine (a
vasoconstrictor and stimulant common in cold
and allergy products), NICOTINE(tobacco), and anx-
iety (stress) may also cause PVCs. PVCs require a
doctor’s evaluation when they occur- frequently
- repeatedly over a period of time rather than in
isolation - with CHEST PAINor discomfort
- with lightheadedness, dizziness, or SYNCOPE
(fainting)
A doctor also should evaluate PVCs in anyone
who has diagnosed CARDIOVASCULAR DISEASE(CVD),
particularly an ARRHYTHMIAdisorder. Occasionally
PVCs can trigger a more serious arrhythmia such
as ventricular tachycardia. An ELECTROCARDIOGRAM
(ECG) can identify PVCs. Because PVCs tend to be
intermittent, the doctor may use a Holter monitor
ECG, which records the heart’s electrical activity
over a period of 24 hours.
Unless PVCs indicate a serious underlying
arrhythmia, cardiologists usually do not treat them.
Often, eliminating potential causes such as caffeine
can put an end to the PVCs. The cardiologist maypremature ventricular contraction (PVC) 97