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.
Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm characterized by rapid and irregular beating.Often it starts as brief periods of abnormal beating which become longer and possibly constant over time. Most episodes have no symptoms.trial fibrillation and a corresponding enlargement of the left atrium may cause an increase in size of the mitral valve annulus. With a sinus rhythm, the mitral annulus undergoes dynamic changes during the cardiac cycle. For example, at the end of diastole the annular area is smaller than at the end of systole.