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.
During atrial fibrillation, the heart's two upper chambers (the atria) beat chaotically and irregularly â out of coordination with the two lower chambers (the ventricles) of the heart. Atrial fibrillation symptoms often include heart palpitations, shortness of breath and weakness. Episodes of atrial fibrillation can come and go, or you may develop atrial fibrillation that doesn't go away and may require treatment.