AVRT entrainment results in PPI-TCL of what?

• A. <115 ms
• B. >115 ms
• C. =115 ms
• D. Not determinable

Answer: (A)

During AVRT entrainment, the postpacing interval minus the tachycardia cycle length (PPI-TCL) tells you how close your pacing site is to the reentrant circuit. If you pace from a site that’s part of the circuit (for example, near the bypass tract or AV nodal region involved in the circuit), the impulse plugs back into the tachycardia quickly, so the PPI closely tracks the TCL. That makes the PPI-TCL value small, typically less than about 115 ms.

If your pacing site is far from the circuit, the impulse has to travel to the circuit and back, making the PPI-TCL noticeably larger—often well above 115 ms. So the best answer is that AVRT entrainment yields a PPI-TCL shorter than 115 ms.