Which syndrome results from failure of the sinus node to regulate the heart's rhythm?

Sick sinus syndrome is a condition that arises from the malfunction of the sinus node, which is the heart's natural pacemaker. This syndrome involves a variety of rhythm abnormalities due to the inability of the sinus node to generate regular electrical impulses or to properly conduct those impulses in a timely manner.

In sick sinus syndrome, patients may experience bradycardia, tachycardia, or alternating rhythms of both bradycardia and tachycardia, all stemming from dysfunction at the level of the sinus node. This can lead to symptoms such as dizziness, fatigue, and syncope, resulting from the heart's inadequate ability to maintain a normal rhythm and appropriate cardiac output.

The other syndromes listed do not primarily result from the failure of the sinus node's function. Bradycardia syndrome refers to a general slowing of the heart rate but does not specify the origin. Wolff-Parkinson-White syndrome is characterized by the presence of an abnormal electrical pathway in the heart, leading to tachycardia, rather than a failure of the sinus node. Atrial fibrillation is an irregular and often rapid heart rate that occurs due to issues within the atria, unrelated to the sinus node's inability to regulate rhythm.