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.
A-fib may be linked to conditions such as high blood pressure (hypertension), coronary artery disease, heart valve disease, heart failure, chronic lung disease or a clot in the lung (pulmonary embolism), among others. But in 10 percent of cases, A-fib is not associated with any other disease. Heart palpitations.