Atrial Fibrillation (cont.)
How is atrial fibrillation treated?
The treatment of AF is multi-faceted and involves 1) reversing the
factors that cause AF, 2) slowing the heart rate with medications, 3) preventing
strokes, 4) converting AF to a normal heart rhythm with medications or
electrical shock, 5) preventing the recurrence of AF with medications, and 6)
using procedures (e.g., pacemakers, defibrillators, surgery) to prevent episodes
of AF.
Reversing the risk factors that cause atrial fibrillation
An important first step in the treatment of atrial fibrillation is to uncover
and correct conditions (such as hyperthyroidism or use of stimulant drugs) that
can cause atrial fibrillation. These steps include:
- Stopping the use of stimulant drugs and excessive
alcohol intake
- Controlling high blood pressure
- Correcting hyperthyroidism (too much thyroid hormone)
and low blood oxygen levels
- Controlling heart failure and treating the diseases of the heart and the
lungs that can cause AF
Slowing the heart rate with medications
Having excluded or corrected the factors that cause AF, the next
step when the ventricles are beating too rapidly usually is to slow the rate at
which the ventricles beat.
Available medications. Patients with AF and healthy AV nodes usually
have ventricles that beat rapidly. Medications are necessary to slow down the
rapid heart rate. Medications to slow the heart rate in AF include:
These medications slow the heart rate by retarding conduction of
the electrical discharges through the AV node. These medications, however, do
not usually convert AF back into a normal rhythm. Other drugs or treatments are
necessary to achieve a normal heart rhythm.
Benefits of controlling the rate. In patients with rapid ventricle
contractions as a result of AF, slowing the rate of ventricular contractions
improves the heart's efficiency in delivering blood (by allowing more time
between contractions for the ventricles to fill with blood) and relieves the
symptoms of inadequate flow of blood - dizziness, weakness, and shortness of
breath.
With chronic, sustained AF, doctors may decide to leave some patients in AF
provided that their heart rates are under control, the output of blood from the
ventricles is adequate, and their blood is adequately thinned to prevent
strokes. This form of treatment is called rate control therapy (see below).
Limitations of medications for controlling the heart rate. In patients
with diseased AV nodes, ventricular contractions may be slower than patients who
have normal AV nodes. Moreover, some elderly patients with AF are extremely
sensitive to medications that slow the rate of ventricular contractions, usually
because of a diseased AV node. In these patients, the heart rate can become
dangerously slow with small doses of medications to slow the heart. This
condition is referred to as tachycardia-bradycardia syndrome, or "sick sinus
syndrome." Patients with tachycardia-bradycardia syndrome need medications to
control the fast heart rate and a pacemaker to provide a minimum safe heart
rate.
Medications used in slowing AF generally cannot convert
AF to a normal rhythm. Therefore these patients are at risk for the formation of
blood clots in the heart and strokes and will need prolonged blood thinning with
anticoagulants like warfarin
(Coumadin).
Next: Anticoagulation to prevent blood clots and strokes »
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