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, or A-Fib, is a common arrhythmia in which the heart's upper chambers (the atria) quiver rather than contract (squeeze) normally, sometimes as many as 600 times per minute. This causes the heart's lower chambers (the ventricles) to contract out of rhythm and faster than normal. Without treatment, A-Fib can lead to other serious heart problems, like enlargement of the heart (called cardiomyopathy) and heart failure (when the heart cannot fill or pump enough blood to meet the body's needs).