Answer: I don't think is particularly difficult but it serves to remind us all that there are three criteria to be met before we can call it complete heart block:
- Ventricular rate must be less than 40 (some say 45). If there is complete HB then the heart is dependent on a ventricular PM which should be in the 20-40 range.
- All phases of the cardiac cycle must be probed i.e. all different intervals must be tried. Where this comes into importance is when there is an atrial brady; if the atrial rate is low, then the cardiac cycle won't be tested sufficiently to call it complete HB.
- There must be no conduction through the AV node.
