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Back to Cardiovascular Diseases
Atrial fibrillation
Updated: September 22, 2006
Types of atrial tachycardia
- Benign
- Incessant ectopic
- Multifocal
- Atrial tachycardia with block (digoxin toxicity)
Symptoms and signs
The symptoms of atrial fibrillation (AF) include palpitations,
irregular heart beat, shortness of breath, chest discomfort, and
dizziness. Many patients experience feelings of weakness, caused by the
heart’s diminished pumping ability. The awareness of a rapid and/or
irregular heart beat also may cause some patients to feel quite anxious.
Patients who have otherwise healthy hearts may be better able to
tolerate AF. People with underlying heart disease are generally less
able to tolerate AF without complication. Once AF becomes symptomatic,
it becomes more serious as it indicates that the heart is failing to
pump adequate amounts of blood to the body.
The ventricular rate depends on the degree of atrioventricular block,
but when 1:1 conduction occurs a rapid ventricular response may result.
Increasing the degree of block with carotid sinus massage or adenosine
may aid the diagnosis.
Diagnosis
Atrial fibrillation can be strongly suspected simply by feeling the
pulse, but a complete diagnosis calls for full medical investigation.
One of the most important tests is the electrocardiograph (ECG),
which can also give evidence of any previous heart disease that may have
been the cause of the condition. If the AF is intermittent, it may be
necessary for the patient to wear a Holter monitor for an extended
period of time in order to catch one or more episodes of AF. Often the
ECG and Holter are used in conjunction with a chest x-ray and
echocardiogram, which shows the heart walls as they are beating. ECG
features in AF include:
- P waves absent; oscillating baseline f (fibrillation) waves
- Atrial rate 350-600 beats/min
- Irregular ventricular rhythm
- Ventricular rate 100-180 beats/min
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Fast atrial fibrillation may be difficult to distinguish from other
tachycardias. The RR interval remains irregular, however, and the
overall rate often fluctuates. Mapping R waves against a piece of paper
or with calipers usually confirms the diagnosis.
Routine blood tests can also be useful in the diagnosis. They may
show anemia, which may be complicating the situation, impaired kidney
function, or thyroid gland overactivity (thyrotoxicosis). A chest X-ray
in a young patient may suggest the presence of heart disease that may
have been present from birth. In an older patient it can give
information on the size of the heart and whether heart failure is
present.
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