ABSTRACT
Thus the ventricular (QRS complex) rate will be exactly half of the atrial (P wave) rate. • Second-degree atrioventricular block is often categorized as Mobitz type 1 or Mobitz type 2, depending upon whether or not the PR interval lengthens before a P wave fails to conduct. However, in 2:1 atrioventricular block it is impossible to say whether the PR interval would have lengthened or not, as there is only one PR interval to measure before the non-conducted P wave occurs. It is therefore impossible to place this into either the Mobtiz type 1 or the Mobitz type 2 category, and so this form of second-degree atrioventricular block is placed in its own category of 2:1 atrioventricular block.
