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.
Atrial fibrillation (also referred to as AF or AFib) is the most common type of irregular heartbeat. It is found in about 2.2 million Americans. Its frequency increases with age. If you have AF, the electrical impulse does not travel in an orderly fashion through the atria.ou may have atrial fibrillation without having any symptoms at all. If you have symptoms, they may include: 1  Heart palpitations (a sudden pounding, fluttering, or racing feeling in the chest). 2  Fatigue or lack of energy. 3  Dizziness (feeling faint or light-headed).