How is a sinus arrest defined?

A sinus arrest is defined as a temporary cessation of electrical activity in the sinus node, which results in the absence of P-QRS-T complexes on an ECG for a period longer than that of a single PQRST sequence. This specifically means that if the sinus node fails to initiate an impulse, the heart will not beat during that interval, leading to a gap in the rhythm where one or more P-QRS-T complexes are absent.

In clinical practice, this definition is crucial for diagnosis because it helps differentiate sinus arrest from other types of arrhythmias where rhythm may be irregular or where the heart rate may be accelerated or varied. Recognizing that a sinus arrest must involve the loss of more than one complete cardiac cycle underscores its significance in assessing a patient's cardiac function and warrants further investigation into the underlying causes or implications for treatment.