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.
Symptoms of AFib. The symptoms of AFib may feel similar to those of a heart attack: 1  Heart palpitations. 2  Chest discomfort or pressure. 3  Chest pain. 4  Lightheadedness. 5  Abdominal pain. 6  Shortness of breath.7  Fatigue. 8  Lack of energy.hen a person experiences a heart attack, they are likely to feel: 1  Chest discomfort or pressure. 2  Chest pain. 3  Shortness of breath. 4  Confusion. 5  Extreme fatigue. 6  Dizziness. 7  Sweating. 8  Nausea. 9  Pain that travels down the arm(s). 10  Pain that goes into the jaw, back, or stomach.