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.
Atrial fibrillation (AF or A-Fib) is a heart rhythm disturbance, that causes an irregular and often very rapid, fluttering heart rate (heart palpitations). A-Fib occurs when the upper chambers of the heart (the atria) beat chaotically and out of sync with the lower chambers (the ventricles).