In a healthy heart, the sinoatrial node⏤or SA node⏤initiates all electrical impulses in the atria.

在健康的心臟中，竇房結是心房中發起所有電脈衝信號的地方。

In atrial fibrillation, electrical impulses are initiated randomly from many other sites called " ectopic sites " in and around the atria, commonly near the roots of pulmonary veins.

當心房顫動時，心房內部與周遭通常位於肺靜脈根部，許多稱為異位點的其他地方便會隨機發出電脈衝信號。

These unsynchronized chaotic electrical signals cause the atria to quiver⏤or fibrillate⏤rather than contract.

這些不同步且混亂的電子信號便會使心房顫抖或顫動，而不是正常地收縮。

Although the atrial rate during atrial fibrillation can be extremely high, most of the electrical impulses do not pass through the atrioventricular, the AV node, to the ventricles.

雖然在心房顫動時心博率可以達到非常的高，但大多的電脈衝信號並沒有經過房室結通往心室。

This is due to refractory properties of the cells of the AV node.

這是因為房室結細胞的無感特性所造成的。

Those that do come through are irregular.

只有非正常的訊號才會通過。

Ventricular rate, or heart rate, is therefore irregular and can range from slow⏤less than 60⏤to rapid⏤more than 100⏤beats per minute.

這使得心博率或心率也跟著變得不正常，且會在低心率（每分鐘低於 60 下）與高心率（每分鐘高於 100 下）間徘徊。

On an ECG, atrial fibrillation is characterized by absence of P-waves and irregular narrow QRS complexes.

在心電圖上，心房顫動的症狀能從 P 波的缺失與異常狹窄的的 QRS 複合波上顯現出來。

Reminder: P-wave represents electrical activity of the SA node that is now obscured by activities of multiple ectopic sites.

小提醒：P 波代表的是竇房結的電子活動現在被多個不同的異位點給阻撓了。

The baseline may appear undulating or totally flat depending on the number of ectopic sites in the atria.

根據心防內部的異位點數量，基線可能呈現些許起伏或是完全平坦的狀況。

In general, larger number of ectopic sites results in flatter baseline.

一般而言，異位點數量越多，基線便會更加平坦。

As the atria do not function properly, the heart puts out less blood, and heart failure may occur.

由於心房並未正常運作，心臟送出的血液便會減少，並可能導致心力衰竭。

The most common complication of atrial fibrillation, however, is the formation of blood clots in the atria.

然而心房顫動最常見的併發症，其實是在心房內部形成血栓。

As the atria do not empty completely into the ventricles, the blood may stagnate inside the atria and blood clots may form.

由於心房無法將所有血液送進心室中，因此血液便有可能在心房中堆積並形成血栓。

These clots may then pass into the bloodstream, get stuck in small arteries, and block them.

這些血栓接著便有可能順著血液流動，最後卡在較小的動脈中並阻塞它們。

When a blood clot blocks an artery in the brain, a stroke may result.

若血栓阻塞了大腦中的動脈，便有可能導致中風。