We hypothesized that adding pin electrodes (PEs) near the ablation tip enhances the assessment of electrical activity and lesion efficacy using electrogram amplitudes (Amp) and maximum frequency spectra (Maxfreq). We used an 8-mm ablation catheter equipped with 461mm PEs radially distributed at 90 u and standard recording rings. Lesions were placed under fluoroscopic and St. Jude NavX guidance to form intercaval (IC), cavotricuspid isthmus (CTI) lines and left atrial linear lesions (LL). Radiofrequency (RF) was delivered for 1 min at settings of 65 u C and 65 watts. Amp and MaxFreq were recorded pre-and post ablation from bipolar PEs, PEs referenced to the 8 mm tip and 8 mm to the first ring electrode. Linear lesion gaps and atrial tachycardia were mapped and ablated using PE recordings. Post-mortem tetrazolium staining of RF lesion assessment was performed. In seven dogs and 217 lesions, Amp showed marked decreases post ablation when measured with the PE compared to the 8-mm tip (77.3¡17.9% decrease versus 27.3¡38.9%, p,0.0001). Using the PE, the MaxFreq decreased significantly compared with the 8mm tip 56¡22.9% versus 11.4¡36.5, p,0.001). Gaps and atrial tachycardia-induced post LL lesions were ablated based on PE electrical activity, indicating gaps and viable tissue. Such discrimination was not possible with the 8-mm electrode. PEs show more dramatic changes in Amp and MaxFreq versus the standard 8-mm tip. The PE enhances the detection of gaps in the linear lesion. We conclude that PEs offer significant improvement in the assessment of RF lesion efficacy and provide a useful index of lesion formation and post-ablation lesion mapping and gap detection.

No abstract