A 3-month old child with complete heart block after surgery for AV canal defect

: We present a case of 75-year-old lady with effort intolerance and baseline ECG showing 2:1 atrio-ventricular block, in whom it was unclear as to requirement of permanent pacing, even after long term ECG monitoring. She underwent a tread mill test during which her QRS became wide and developed complete heart block within 2 minutes of the test. Thus, a simple exercise test helped in confirming level of block to be infra nodal without need for invasive study. In patients with exertional symptoms, even in elderly, and in those where ECG masquerades as a benign entity, exercise testing is useful to differentiate benign cases of atrio-ventricular block from the more serious cases that mandate a pacemaker implantation.

AbstractVarying kinds of AV blocks can occur in the setting of myocardial ischaemia or due to degeneration of conduction system. Wenckebach AV block can present with typical Wenckebach periodicity or atypical periodicity. A variant of atypical Wenckebach periodicity may present like Mobitz II AV block. This is called Pseudo Mobitz II AV block. As we are aware that Mobitz II AV block is more dangerous and can suddenly convert into complete heart block, it is essential that we should try to differentiate between Mobitz and Pseudo Mobitz II blocks. Infact atypical Wenckebach cycles are quite common at both AV node and his Purkinje system.