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 Causes of atrial fibrillation include heart attack, high blood pressure, heart failure, mitral valve diseases (such as mitral valve prolapse), overactive thyroid, blood clots in the lung (pulmonary embolism), alcohol excess, emphysema, and inflammation of heart lining (pericarditis).