User:Mr. Ibrahem/Sinus node dysfunction

Sinus node dysfunction (SND), also known as sick sinus syndrome (SSS), is a group of abnormal heart rhythms caused by malfunction of the sinoatrial node, the heart's primary pacemaker. Early on symptoms may be few. As the disease progresses syncope may occur. Other symptoms may include lightheadedness, palpitations, or chest pain. The heart may beat insufficiently fast during exercise. Complications may include atrial fibrillation.

It involves a slow heart rate with or without periods of a faster heart rate. The slow heart rate may be a sinus bradycardia, sinus pause, or sinoatrial exit block. When periods of a fast heart rate is present it is known as tachy-brady syndrome. The underlying mechanism may include fibrosis, ion channel dysfunction, or remodeling of the sinoatrial node. Other factors that can worsen the condition include medications such as beta blockers or calcium channel blockers, electrolyte abnormalities, low oxygen, and low thyroid. Diagnosis is based on symptoms together with electrocardiogram (ECG) findings.

Treatment involves avoiding factors that worsen the condition and placing a pacemaker. The typical age of onset is around 68 to 74 years old. About 0.2% of people over the age of 65 are affected. Males and females are effected equally frequently. It is the most common reason pacemakers are placed in the United States.