In second-degree atrioventricular nodal block — also known as Wenckebach block or Mobitz Type I AV block — varying failure of conduction through the AV node occurs, such that some P waves may ...

For example, three consecutive P waves may be ... however it is constant in length unlike second-degree AV block Mobitz Type I (Wenckebach) in which the PR interval progressively lengthens until ...