â¢ One plate is pushed beneath the other, or equivalent description. â¢ A trench may be formed at the subduction zone. (ii) Explain how subduction leads to volcanic activity. (2 points: 1 point for a correct explanation of one plate being pushed down and melted and 1. point for a correct explanation of molten material /magma rising to the surface near the zone)
Symptoms of atrial fibrillation occur when the upper chambers of the heart (atria) beat in a disorganized fashion. Atrial fibrillation is a type of arrhythmia. Characteristic symptoms include shortness of breath, palpitations, and lightheadedness.
1 People who have this type of AFib may have episodes only a few times a year or their symptoms may occur every day. These symptoms are very unpredictable and often can turn into a permanent form of atrial fibrillation.  Persistent AFib is defined as an irregular rhythm that lasts for longer than 7 days.