Validation of CTI with the single ablation catheter
In SR, the ablation catheter was positioned on the septal part (at the
CS ostium) of the CTI line and PR interval was measured on surface ECG
from the atrial CS spike to the peak QRS measured on lead II (septal
delay, Figure 1). We used this definition to better define the end of PR
interval, because the beginning of the QRS can be harder to precisely
identify as compared to the peak of the QRS. This measurement was
performed during pacing at 800 ms or 10 bpm faster than the baseline
patient heart rate. Then, pacing at the same cycle length was performed
on the lateral side of the CTI line (lateral delay). PR measurement were
recorded before and after the CTI block was confirmed with the standard
method. Delta PR interval was obtained by subtracting the septal delay
from the lateral delay. Figure 2 shows examples of PR measurement before
and after CTI block achievement.