2. A vessel approaching a blind bend in a river can sound one prolonged blast on the ships' whistle to alert any other vessels to its presence, if another vessel is nearby then they will respond with one prolonged blast on the ships' whistle.
Atrial fibrillation, known as AF or Afib, is an irregular and often very fast heart rate. This may cause symptoms like heart palpitations, fatigue, and shortness of breath. Treating atrial fibrillation is important because it may cause a stroke and negatively impact your quality of life.
Very often people with atrial fibrillation have no symptoms and do not know they are in AFib. On the other hand, those who notice when they are having atrial fibrillation can have symptoms ranging from mild to debilitating. Symptoms of atrial fibrillation include: 1  Rapid beating, pounding, or fluttering sensation in the chest (palpitations)  Lightheadedness.