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.
Some people have no symptoms of atrial fibrillation; however, those that do have symptoms that are numerous. palpitations (a sensation of rapid and irregular heart beat), dizziness or lightheadedness, weak feeling, shortness of breath, chest pain and/or angina, nausea.