Radio-frequency needle technique
In difficult cases with initially unsuccessful TSP due to stiff or
thickened IAS the RF needle technique was utilized. The main advantage
of this technique is that significant mechanical force is not needed for
successful and safe TSP (10). In short, after the long sheath / dilator
/ transseptal needle assembly was positioned at the optimal location on
the IAS (panel D, Figure 1), the transseptal needle was pushed against
the oval fossa. During consistent pressure of the needle and under
uninterrupted ICE guidance the RF energy was applied to the shaft of the
metal needle with the ablation catheter. Due to the expected rise of the
impedance the high impedance cutoff on the RF generator was set to the
maximum value. The RF energy of 20W was generally applied for 5 -10
seconds until the tip of the needle was visualized in the LA cavity
(panel E, Figure 1). The subsequent steps of TSP were as previously
described in Figure 1.