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.
Causes of Atrial Fibrillation AFib is usually caused by damage to the heart structure. Some people are born with abnormalities that cause AFib, while others develop the condition due to high blood pressure, heart attacks, overactive thyroid glands, emphysema, sleep apnea, or previous heart surgeries.