What is difference between sinus arrest exit block and sinus arrhythmia?

Answer 1

Sinus activiy is really not recorded on the ECG(EKG) only the atria's response to it. Hence, Sinus Arrest and Sinus Exit Block are determined on the basis of what we can see. The absense of the P wave and it's recurance at the next expected intereval is considered a Sinus Exit Block; meaning the sinus node did its job, but the impluse was blocked form the rest of the atria. The mechanism of such blocking is not fully understood at this point In sinus arrest the the pause is not accurate to the next expected cardiac cycle thus is considered a sinus arrest - meaning that something stopped the sinus node activity for a time (usually just seconds). Of the two Sinus Exit Block carries the least risk of symptoms for the patient.