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Tachycardia: Difference between revisions
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===Atrial Fibrillation=== | ===Atrial Fibrillation=== | ||
====Pathophysiology:==== | ====Pathophysiology:==== | ||
The pathophysiology of atrial fibrillation is complex and incompletely understood. | The pathophysiology of atrial fibrillation is complex and incompletely understood. In atrial fibrillation there is chaotic depolarisation with multiple foci, that spin around each other. 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 variaty 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). 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 in for instance the 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: | 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: | ||
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* Long standing persistent atrial fibrillation: Persistent atrial fibrillation for more than one year. | * Long standing persistent atrial fibrillation: Persistent atrial fibrillation for more than one year. | ||
* Permanent atrial fibrillation: Accepted atrial fibrillation, no strategies of rhythm control are pursued. | * Permanent atrial fibrillation: Accepted atrial fibrillation, no strategies of rhythm control are pursued. | ||
====Management:==== | ====Management:==== | ||
Atrial fibrillation can be managed with anti-arrhythmic medication or more invasive treatment strategies. Independent of the treatment strategy, proper anti-coagulation is important and necessary in patients with risk factors. | Atrial fibrillation can be managed with anti-arrhythmic medication or more invasive treatment strategies. Studies have shown no benefit of rhyhtm control over rate control, thus the selection of strategy is mainly dependent of patient and atrial fibrillation characteristics. Independent of the treatment strategy, proper anti-coagulation is important and necessary in patients with risk factors. | ||
Rate control | Rate control: In atrial fibrillation the ventricle can have a fast irregular rate that can be difficult to tolerate by a patient. On of the strategies in managing atrial fibrillation is to control ventricular rate <120bpm. In this strategy no attempt is made to achieve sinus rhythm. This is the only treatment option in patients with permanent atrial fibrillation. Due to the fast irregular ventricular rate a dilated tachycardiomyopathy can develop and proper rate control can revert these ventricular changes. Rate control can be achieved with beta-blockers, Ca-antagonist and digoxine. | ||
Rhythm control | Invasive treatment: | ||
Invasive treatment | His-Ablation with pacemaker implantation: Patients with accepted atrial fibrillation and complaints of a fast irregular ventricular frequency who do not tolerate medication can be helped with a targeted His bundle ablation with catheter ablation to induce complete AV-block. A implanted pacemaker can take over the ventricular firing frequency independent of the atrium. | ||
Catheter ablation | Rhythm control: In rhythm control all efforts are made to achieve and maintain sinus rhythm. This can be done with anti-arrhythmic drugs. Most effective are the Class IC and III anti-arrhythmic drugs. Overall rhythm control is difficult and anti-arrhythmic drugs have many (pro-arrhythmic) side effects. Therefore prescription of these drugs should occur with caution. | ||
Invasive treatment: | |||
Medical therapy is not always sufficient to maintain | |||
Catheter ablation: | |||
Surgical treatment | Surgical treatment | ||
Anticoagluation treatment | Anticoagluation treatment | ||