ECG Quiz 2

ECG Quiz 2

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Though there is superficial resemblance to 2:1 AV block, it is actually complete AV block as illustrated in the lead II rhythm strip at the bottom of the tracing. All the four criteria for complete heart block on ECG are satisfied:
1. Regular PP interval
2. Regular RR interval
3. PP interval shorter than RR interval (atrial rate higher than ventricular rate)
4. Totally varying PR interval
When complete heart block mimics 2:1 AV block in short strips, the phenomenon is called ‘accrochage’. Narrow QRS escape rhythm indicates that the level of the block is above the His bundle (supra Hisean block). A good ventricular rate and supra Hisean block in this ECG from a child are features of congenital complete heart block. T wave inversion in anterior leads could be a juvenile pattern. If it is seen in an adult with an Infra Hisean block it would suggest a recent Stokes-Adam attack and consequent hypoxia. In that case one would expect much broader T wave inversions with a prolonged QT interval.