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Tachycardia: Difference between revisions
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The pathophysiology of atrial fibrillation is complex and incompletely understood.<cite>schotten</cite> In atrial fibrillation there is chaotic depolarisation from multiple foci, self-perpetuating micro re-entry circuits. In most patients the trigger of atrial fibrillation results from extra beats in from the pulmonary veins. This is due to myocardial sleeves growing into the pulmonary veins, which are triggered to fire extra beats due a variety of modulators (e.i. the autonomic nerve system). These triggers can trigger the atria into forming multiple self-perpetuating re-entry circuits. The ability of the atria to sustain atrial fibrillation is dependable on atrial structural changes (fibrosis/inflammation). Due to this fast and rapid activation of the atria, there is no functional mechanical activity left. This results in the most feared complication of atrial fibrillation, namely forming of blood clots (with for instance stroke as a result). The atrial standstill does not effectively pump blood to the ventricle, and blood can coagulate the left atrium or left atrial appendage. The strokes resulting from atrial fibrillation are often more severe than other causes of stroke. | The pathophysiology of atrial fibrillation is complex and incompletely understood.<cite>schotten</cite> In atrial fibrillation there is chaotic depolarisation from multiple foci, self-perpetuating micro re-entry circuits. In most patients the trigger of atrial fibrillation results from extra beats in from the pulmonary veins. This is due to myocardial sleeves growing into the pulmonary veins, which are triggered to fire extra beats due a variety of modulators (e.i. the autonomic nerve system). These triggers can trigger the atria into forming multiple self-perpetuating re-entry circuits. The ability of the atria to sustain atrial fibrillation is dependable on atrial structural changes (fibrosis/inflammation). Due to this fast and rapid activation of the atria, there is no functional mechanical activity left. This results in the most feared complication of atrial fibrillation, namely forming of blood clots (with for instance stroke as a result). The atrial standstill does not effectively pump blood to the ventricle, and blood can coagulate the left atrium or left atrial appendage. The strokes resulting from atrial fibrillation are often more severe than other causes of stroke. | ||
====Clinical diagnosis:==== | ====Clinical diagnosis:==== | ||
Atrial fibrillation is the most common supraventricular arrhythmia in Western society. It is characterized by the absence of clear P-waves on the surface ECG and an irregular ventricular ventricular rate. On physical examination an irregular pulse can be felt, however this is not diagnostic of atrial fibrillation as other causes can cause an irregular pulse (atrial or ventricular extra systoles). The cardiac output is reduced due to lack of atrial kick. Furthermore due to the higher ventricular rate the heart has not enough time to completely fill with blood. Atrial fibrillation is classified according to the clinical presentation of atrial fibrillation:<cite> | Atrial fibrillation is the most common supraventricular arrhythmia in Western society. It is characterized by the absence of clear P-waves on the surface ECG and an irregular ventricular ventricular rate. On physical examination an irregular pulse can be felt, however this is not diagnostic of atrial fibrillation as other causes can cause an irregular pulse (atrial or ventricular extra systoles). The cardiac output is reduced due to lack of atrial kick. Furthermore due to the higher ventricular rate the heart has not enough time to completely fill with blood. Atrial fibrillation is classified according to the clinical presentation of atrial fibrillation:<cite>Camm2010</cite> | ||
* Paroxysmal atrial fibrillation: Episodes atrial fibrillation lasting shorter than 7 days and terminating spontaneously | * Paroxysmal atrial fibrillation: Episodes atrial fibrillation lasting shorter than 7 days and terminating spontaneously | ||
* Persistent atrial fibrillation: Episodes of atrial fibrillation not terminating spontaneously or lasting longer than 7 days | * Persistent atrial fibrillation: Episodes of atrial fibrillation not terminating spontaneously or lasting longer than 7 days | ||