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.
In some patients, if the heart beats too slowly during atrial fibrillation, this can also cause symptoms. An irregular pulse (usually detected by listening to the heart with stethoscope) is the most common sign of atrial fibrillation at physical examination. Table 1. Common signs and symptoms of atrial fibrillation.