Final answer:
The paced cycle length (PCL) is faster than the tachycardia cycle length (TCL) when performing a pacing manoeuvre. This difference in cycle lengths is significant when interpreting EGMS because it helps identify the origin of the electrical signals.
Step-by-step explanation:
When performing a pacing manoeuvre, the paced cycle length (PCL) refers to the time between each pacing stimulus, while the tachycardia cycle length (TCL) is the time between two consecutive heartbeats during tachycardia. In general, the PCL is faster than the TCL when a pacing manoeuvre is performed. This difference in cycle lengths is significant when interpreting electrograms (EGMs) because it helps identify the origin of the electrical signals. By comparing the PCL and TCL, doctors can determine whether the electrical signals are originating from the heart's natural electrical system or from an external pacing source.