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.
Loss of consciousness is the most common sign of ventricular fibrillation. A condition in which the lower chambers of your heart beat too fast (ventricular tachycardia) can lead to ventricular fibrillation. Signs and symptoms of ventricular tachycardia include: 1  Chest pain.2  Rapid heartbeat (tachycardia). 3  Dizziness.4  Nausea.5  Shortness of breath. 6  Loss of consciousness.arly signs and symptoms. A condition in which the lower chambers of your heart beat too fast (ventricular tachycardia) can lead to ventricular fibrillation. Signs and symptoms of ventricular tachycardia include: 1  Chest pain. 2  Rapid heartbeat (tachycardia). 3  Dizziness.