Diagnostic criteria

  P waves are absent.

  There are fibrillation (f) waves instead of P waves. The f waves result in an
oscillating irregular baseline.

  The R-R intervals are not equal resulting in an irregular rhythm (
irregularly irregular).



Triggers of atrial fibrillation

  Atrial premature contractions - APC ( the most frequent )

  Atrial flutter

  Supraventricular tachycardias

  Bradycardia

  Acute atrial stretch




Clinical significance

  Atrial fibrillation patients usually have a ventricular rate of 100-180 beats/minute.

      This is why these patients frequently complain of palpitation.

  A lower ventricular rate should suggest atrioventricular block or the use of medications

      decreasing the ventricular rate (digoxine, beta blocker, verapamil, diltiazem, amiodarone).

  Wolff-Parkinson-White (WPW) Syndrome should be suspected if there is a higher ventricular rate.

      This high ventricular response may cause syncope or even death in these patients.

  Since the R-R intervals continously change in atrial fibrillation patients, the heart rate on the monitor

      also changes continously. In such patients, the instantenous heart rates depicted on the monitor

      usually does not give the average ventricular rate of that patient.

  Since there is no atrial contraction, the presence of atrial fibrillation decreases cardiac output by
20-25%.

      This is why these patients usually complain of exercie intolerance and easy fatigability.

  Atrial fibrillation results in atrial statis which predisposes to the
thrombus formation in the atria.

      This results in increased risk of systemic embolism.

      Unless contraindicated, patients with atrial fibrillation are generally advised to be anticoagulated.

  In patients with a very high ventricular rate,

      it may be
difficult to recognize the irregularity of the R-R intervals at first glance.

  In some patients, atrial fibrillation is not persistent.

      24-hour Holter monitoring may be very useful in such patients since it may record the paroxysmal attacks.

  When compared with atrial flutter,
the control of ventricular rate is easier in atrial fibrillation.







ECG 1. Three criteria of the atrial fibrillation: absent P waves, oscillating irregular baseline, irregular R-R intervals.

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ECG 2. Atrial fibrillation with a slow ventricular response.

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ECG 3. Paroxysmal atrial fibrillation attack observed in Holter recording.

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ECG 4. Atrial fibrillation in a patient with old anterior myocardial infarction. P waves are absent, R-R intervals are irregular
and baseline is oscillating.

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ECG 5. Fine atrial fibrillation with a slow ventricular response. P waves are absent, R-R intervals are irregular and baseline is
finely oscillating (no coarse fibrillation waves are observed).

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ECG 6a. The above ECG resembles atrial fibrillation at a first glance: P waves seem to be absent, baseline is oscillating and
R-R intervals are irregular. The calibration of the ECG is 10mm/mV.
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ECG 6b. Immediately after recording of the ECG 6a, the calibration of the ECG was adjusted as 20mm/mV to see the details
clearly. The P waves are easily observed now excluding the diagnosis of atrial fibrillation. The patient will not receive
unnecessary oral anticoagulant therapy.

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ECG 7.
f (fibrillation) waves are very clearly seen in this patient with coarse wave atrial fibrillation. Fibrillation waves are
irregular and are not uniform in shape. These findings differentiate it from atrial flutter. Generally, f waves are not this large in
patients with AF.

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ECG 8. Paroxysmal atrial fibrillation detected in the Holter recording of an old woman.
The first and the last beats of the paroxysmal atrial fibrillation are marked above.

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ECG 9. Coexistence of left bundle branch block and atrial fibrillation.

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ECG 10a. The ECG above is from a 62 years-old woman with baseline drift, sinus arrhythmia and low amplitude P waves.
The diagnosis may be atrial fibrillation at first glance.

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ECG 10b. The ECG was recorded again. Sinus arrhythmia still persists but lesser baseline drift permits easy recognition
of P waves.

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ECG 10c. Re-recording of the ECG at a calibration of 20 mm/mV shows P waves more clearly.

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