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.
1 People who have this type of AFib may have episodes only a few times a year or their symptoms may occur every day. These symptoms are very unpredictable and often can turn into a permanent form of atrial fibrillation.  Persistent AFib is defined as an irregular rhythm that lasts for longer than 7 days.