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{{Chapter|Supraventricular Rhythms}} | {{Chapter|Supraventricular Rhythms}} | ||
{{Arrhythmias| | {{Arrhythmias| | ||
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| p_wave = absent | | p_wave = absent | ||
| adenosine = reduces heart rate | | adenosine = reduces heart rate | ||
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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. | 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. | ||
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Image:afib_detail.jpg|Detail of 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: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> | </gallery> | ||