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.
Causes of Atrial Fibrillation AFib is usually caused by damage to the heart structure. Some people are born with abnormalities that cause AFib, while others develop the condition due to high blood pressure, heart attacks, overactive thyroid glands, emphysema, sleep apnea, or previous heart surgeries.