Atrial fibrillation (sometimes abbreviated as AF or A-fib) is an abnormal heart rhythm characterized by rapid and irregular beating. Often it starts as brief periods of abnormal beating which become longer and possibly constant over time. Most episodes have no symptoms. Occasionally there may be heart palpitations, fainting, shortness of breath/dyspnea, or chest pain. The disease increases the risk of heart failure, dementia, and stroke.
ECG Findings of Atrial Fibrillation include:
Other features may include:
The Acronym P.I.R.A.T.E.S. is sometimes used to remember the causes of atrial fibrillation which include:
Mechanism of Atrial Fibrillation:
The mechanisms underlying Atrial Fibrillation are not fully understood but it requires an initiating event such as focal atrial activity ( PACs) and underlying heart pathology such as structural heart disease for maintenance (i.e. dilated left atrium).
Two common mechanisms which are frequently cited in the pathogenesis include:
1. Focal activation – In which AF originates from an area of focal activity. This activity may be triggered, due to increased automaticity, or from micro re-entry. Often located in the pulmonary veins.
2. Multiple wavelet mechanism – In which multiple small wandering wavelets are formed. The fibrillation is maintained by re-entry circuits formed by some of the wavelets. This process is potentiated in the presence of a dilated Left Atrium — the larger surface area facilitates continuous waveform propagation.
Classification Of AF:
Classification is based on the presentation and duration of atrial fibrillation as defined below:
First episode – initial detection of AF regardless of symptoms or duration
Recurrent AF – More than 2 episodes of AF
Paroxysmal AF – Self terminating episode < 7 days
Persistent AF – Not self terminating, duration > 7 days
Long-standing persistent AF – > 1 year
Permanent (Accepted) AF – Duration > 1 yr in which rhythm control interventions are not pursued or are unsuccessful
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