684
P A R T 8
Drugs acting on the cardiovascular system
causing feelings of nausea and abdominal pain; swollen
legs and feet; and dependent oedema in the coccyx or
other dependent areas, with decreased peripheral pulses
and hypoxia of those tissues. In addition, with left-sided
failure, oedema of the lungs reflected in engorged vessels
and increased hydrostatic pressure throughout the
cardiovascular system is also seen (Figure 44.3).
Left-sided heart failure
Left-sided HF reflects engorgement of the pulmonary
veins, which eventually leads to difficulty in breathing.
The person complains of
tachypnoea
(rapid, shallow res
pirations),
dyspnoea
(discomfort with breathing, often
accompanied by a panicked feeling of being unable to
breathe), and
orthopnoea
(increased difficulty breath
ing when lying down). Orthopnoea occurs in the supine
position when the pattern of blood flow changes because
of the effects of gravity, which increases pressure and
perfusion in the lungs. Orthopnoea is usually relieved
when the person sits up, thereby reducing the blood
flow through the lungs. The degree of HF is often calcu
lated by the number of pillows required to get relief (e.g.
one-pillow, two-pillow, or three-pillow orthopnoea).
The person with left-sided HF may also experience
coughing and
haemoptysis
(coughing up of blood). Rales
may be present, signalling the presence of fluid in the
lung tissue. In severe cases, the person may develop pul
monary oedema; this can be life-threatening because, as
the spaces in the lungs fill up with fluid, there is no place
for gas exchange to occur.
Right-sided heart failure
Right-sided HF usually occurs as a result of chronic
obstructive pulmonary disease (COPD) or other lung
diseases that elevate the pulmonary pressure. It often
results when the right side of the heart, normally a very
low-pressure system, must generate more and more force
to move the blood into the lungs. It also commonly
occurs with ageing, when the venous system fails to
deliver blood to the heart effectively and the hydrostatic
pressure in the venous end of the capillary increases,
leading to a loss of fluid in the tissues and changes in the
overall efficiency of the vascular system.
In right-sided HF, venous return to the heart is
decreased because of the increased pressure in the right
side of the heart. This causes congestion and a backup
of blood in the systemic system. Jugular venous pressure
(JVP) rises and can be seen in distended neck veins,
reflecting increased central venous pressure (CVP). The
liver enlarges and becomes congested with blood, which
leads initially to pain and tenderness and eventually to
liver dysfunction and jaundice.
Dependent (lower) areas develop oedema or swelling
of the tissues as fluid leaves the congested blood vessels
and pools in the tissues. Pitting oedema in the legs is a
common finding, reflecting fluid pooling in the tissues.
For example, when the person with right-sided HF
changes position and the legs are no longer dependent,
the fluid moves back into circulation to be returned
to the heart. This increase in cardiovascular volume
increases blood flow to the kidneys, causing increased
urine output. This is often seen as
nocturia
(excessive
voiding during the night) in a person who is up and
around during the day and supine at night. The person
may need to get up during the night to eliminate all of
the urine that has been produced as a result of the fluid
shift.
Treatments
Several different approaches are used to treat HF. This
chapter focuses on the cardiotonic drugs (also called
inotropic drugs) that work to directly increase the force
of cardiac muscle contraction. Other drug therapies
used to treat HF include the following:
• Vasodilators, such as angiotensin-converting-
enzyme (ACE) inhibitors and nitrates, decrease
cardiac workload, relax vascular smooth muscle to
decrease afterload and allow pooling in the veins,
Left-sided HF
Right-sided HF
anxiety
splenomegaly
hepatomegaly
elevated jugular
venous pressure
tachypnoea
dyspnoea
orthopnoea
haemoptysis
rales
cardiomegaly
S
3
increased heart
rate
GI upset
nausea
abdominal
pain
decreased
peripheral
pulses
hypoxia
decreased renal
perfusion when
upright
increased renal
perfusion when
supine nocturia
pitting oedema
weakness/fatigue
FIGURE 44.3
Signs and symptoms of heart failure (HF).
