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, 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).