Second degree AV block, mobitz II
See brief interpretation of EKG recording above
– only the 6 precordial leads are seen
– series of constant PR intervals and QRS complexes followed by a non-conducting p wave (second degree heart block, mobitz type 2)
– also: rSR’ configuration in V1 and QRS ≥ 0.12 s. (right bundle branch block, RBBB)
In second degree atrioventricular (AV) block Mobitz type II a period of PR intervals of constant lengths and corresponding QRS complexes is followed by a P wave failing to conduct to the ventricles. Though the PR intervals may be prolonged, they do not lengthens progressively up to the non-conducting P wave as in second degree AV block, Mobitz type I.
Mobitz type II second degree heart block occurs intermittent, often in a non-predicting pattern. The lesion is situated below the atrioventricular node – that is to the bundle of His or the bundle branches. Therefore it is common to see a co-existent bundle branch block (as in the tracings above) when a Mobitz type II heart block is present. Mobitz type 2 second degree heart block may degenerate into complete heart block and vertigo and syncope may occur. Thus, the block is considered more malignant than Mobitz type I block and will usually require pacemaker implantation.