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 is often referred to as sick sinus syndrome because the sinoatrial (sinus) node in the right atrium controls the electrical impulses. The cause of atrial fibrillation is not always known. Conditions that can cause damage to the heart and lead to atrial fibrillation include: 1  high blood pressure.  congestive heart failure.
Very often people with atrial fibrillation have no symptoms and do not know they are in AFib. On the other hand, those who notice when they are having atrial fibrillation can have symptoms ranging from mild to debilitating. Symptoms of atrial fibrillation include: 1  Rapid beating, pounding, or fluttering sensation in the chest (palpitations)  Lightheadedness.