Atrial Fibrillation

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This is part of: Supraventricular Rhythms
Atrial fibrillation
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Atrial rate 400-600 bpm
Ventricular rate 75-175 bpm
Regularity irregular
Origin atria (SVT)
P-wave absent
Effect of adenosine reduces heart rate
Example ECG: {{{example}}}
Example ECG2: {{{example2}}}

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 [1]), ischemia, hyperthyreoidism, alcohol abuse.

Atrial fibrillation can be catechorized as follows:

  • First documented episode
  • Recurrent atrial fibrillation: after two or more episodes.
  • Paroxysmal atrial fibrillation: if recurrent atrial fibrillation spontaneously converts to sinus rhythm.
  • Persisting atrial fibrillation: if an episode of atrial fibrillation persists more than 7 days.
  • Permanent atrial fibrillation: if atrial fibrillation persists after an effort of electrical or chemical cardioversion

Lone AF is atrial fibrillation in patients younger than 60 years in whom no clinical or electrocardiographic signs of heart or lung disease are present. These patiens have a favourable prognosis regarding thrombo-embolic events.

Non-valvular atrial fibrillation is atrial fibrillation in patients without heart valve disease or heart valve replacement or repair. [2]

Treatment strategies include:[3][4][5]

  • 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.


Examples

References

  1. Kelley GP, Stellingworth MA, Broyles S, and Glancy DL. Electrocardiographic findings in 888 patients > or =90 years of age. Am J Cardiol 2006 Dec 1; 98(11) 1512-4. doi:10.1016/j.amjcard.2006.06.055 pmid:17126661. PubMed
  2. Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Le Heuzey JY, Kay GN, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, and Wann S. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation-executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients with Atrial Fibrillation). Eur Heart J 2006 Aug; 27(16) 1979-2030. doi:10.1093/eurheartj/ehl176 pmid:16885201. PubMed
  3. Van Gelder IC, Hagens VE, Bosker HA, Kingma JH, Kamp O, Kingma T, Said SA, Darmanata JI, Timmermans AJ, Tijssen JG, and Crijns HJ. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med 2002 Dec 5; 347(23) 1834-40. doi:10.1056/NEJMoa021375 pmid:12466507. PubMed
  4. Hohnloser SH, Kuck KH, and Lilienthal J. Rhythm or rate control in atrial fibrillation--Pharmacological Intervention in Atrial Fibrillation (PIAF): a randomised trial. Lancet 2000 Nov 25; 356(9244) 1789-94. pmid:11117910. PubMed
  5. Carlsson J, Miketic S, Windeler J, Cuneo A, Haun S, Micus S, Walter S, and Tebbe U. Randomized trial of rate-control versus rhythm-control in persistent atrial fibrillation: the Strategies of Treatment of Atrial Fibrillation (STAF) study. J Am Coll Cardiol 2003 May 21; 41(10) 1690-6. pmid:12767648. PubMed

External Links

Wikipedia: Atrial Fibrillation