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Atrial Fibrillation: Difference between revisions
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{{Chapter|Supraventricular Rhythms}} | |||
{{Arrhythmias| | {{Arrhythmias| | ||
| name = Atrial fibrillation | | name = Atrial fibrillation | ||
| Line 6: | Line 7: | ||
| regularity = irregular | | regularity = irregular | ||
| origin = atria (SVT) | | origin = atria (SVT) | ||
| p_wave = | | p_wave = absent | ||
| adenosine = reduces heart rate | | adenosine = reduces heart rate | ||
}} | }} | ||
During atrial fibrillation the atria show chaotic depolarisation with multiple foci. Mechanically the atria stop contracting after several days to weeks of atrial fibrillation, the result of the ultra-rapid depolarisations that occur in the atria, typically around 400 bpm, but up to 600 bpm. At the AV node 'every now and then' a beat is conducted to the ventricles, resulting in an irregular ventricular rate, which is the typical ECG characteristic of atrial fibrillation. Sometimes atrial fibrillation results in a course atrial flutter wave on the ECG, but the baseline can also be flat. A flat baseline is more often seen in long standing atrial fibrillation. The cardiac stroke volume is reduced by 10-20% during atrial fibrillation, as the 'atrial kick' is missing and because the heart does not have time to fill at the often higher ventricular rate. Causes | <flashow>http://nl.ecgpedia.org/images/7/79/Atrial_Fibrillation.swf|align=right|height=300px|width=300px</flashow> | ||
During atrial fibrillation the atria show chaotic depolarisation with multiple foci. Mechanically the atria stop contracting after several days to weeks of atrial fibrillation, the result of the ultra-rapid depolarisations that occur in the atria, typically around 400 bpm, but up to 600 bpm. At the AV node 'every now and then' a beat is conducted to the ventricles, resulting in an irregular ventricular rate, which is the typical ECG characteristic of atrial fibrillation. Sometimes atrial fibrillation results in a course atrial flutter wave on the ECG, but the baseline can also be flat. A flat baseline is more often seen in long standing atrial fibrillation. The cardiac stroke volume is reduced by 10-20% during atrial fibrillation, as the 'atrial kick' is missing and because the heart does not have time to fill at the often higher ventricular rate. | |||
'''Causes''' age (+- 10% of 70+ year olds and 15% of 90+ year olds have AFIB <cite>kelley</cite>), ischemia, hyperthyreoidism, alcohol abuse. | |||
'''Atrial fibrillation can be catechorized as follows:''' | '''Atrial fibrillation can be catechorized as follows:''' | ||
*'''First documented episode | *'''First documented episode''' | ||
*'''Recurrent atrial fibrillation:''' after two or more episodes. | *'''Recurrent atrial fibrillation:''' after two or more episodes. | ||
*'''Paroxysmal atrial fibrillation:''' if recurrent atrial fibrillation spontaneously converts to sinus rhythm. | *'''Paroxysmal atrial fibrillation:''' if recurrent atrial fibrillation spontaneously converts to sinus rhythm. | ||
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''Non-valvular atrial fibrillation'' is atrial fibrillation in patients without heart valve disease or heart valve replacement or repair. <cite>ESCAF</cite> | ''Non-valvular atrial fibrillation'' is atrial fibrillation in patients without heart valve disease or heart valve replacement or repair. <cite>ESCAF</cite> | ||
'''Treatment strategies include:'''<cite>RACE</cite><cite>PIAF</cite><cite>STAF</cite> | |||
*''Rate control:'' accept atrial fibrillation and focus on symptom relief and prevention of tachycardias. Typically with beta-blockers and digoxin. Target rate is < 100 bpm. | |||
*''Rhythm control:'' trying to keep the patient in normal sinus rhythm. Typically with anti-arrhythmics like amiodarone, flecainide, and sotalol, or electrical cardioversion, or with radiofrequency catheter ablation. | |||
In both cases anti-coagulants are needed to prevent embolic stroke. | |||
{{clr}} | {{clr}} | ||
===References | ==Examples== | ||
<gallery caption:"Examples of atrial fibrillation"> | |||
Image:afib_ecg.jpg|Atrial fibrillation with reasonable rate control | |||
Image:afib_f_VR_ecg.jpg|Atrial fibrillation with rapid ventricular rate | |||
Image:afib_detail.jpg|Detail of atrial fibrillation with rapid ventricular rate | |||
Image:cardioversion_from_afib.jpg|Atrial fibrillation electrically cardioverted into sinusrhythm | |||
Image:afib_V1.png|atrial fibrillation with marked organization in V1 (which is close to the right atrial appendage), this is not atrial flutter. | |||
</gallery> | |||
==References== | |||
<biblio> | <biblio> | ||
#ESCAF pmid=16885201 | #ESCAF pmid=16885201 | ||
#kelley pmid=17126661 | #kelley pmid=17126661 | ||
#RACE pmid=12466507 | |||
#PIAF pmid=11117910 | |||
#STAF pmid=12767648 | |||
</biblio> | </biblio> | ||
==External Links== | |||
[[w:Atrial Fibrillation|Wikipedia: Atrial Fibrillation]] | |||