Novel Ablation Catheter Technology that Improves Mapping Resolution and Monitoring of Lesion Maturation

Abstract

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.

Observations on Attenuation of Local Electrogram Amplitude and Circuit Impedance During Atrial Radiofrequency Ablation: An In vivo Investigation Using a Novel Direct Endocardial Visualization Catheter

“…Interesting new developments in ablation catheter technology are providing new insights into the dynamics of local electrogram attenuation and RF lesion formation . Avitall et al .…”

“…The local electrogram amplitude attenuation is widely used to guide ablation, with an 80% diminution of electrogram being considered evidence for adequate lesion size by several investigators . The relationship between lesion growth and electrogram diminution has not been studied in detail until the recent introduction of microelectrode (ME) embedded catheters . Impedance decrement during ablations is another metric used to guide ablation time, and has been studied extensively for its usefulness as a surrogate marker for effective lesion formation and also to predict complications; however, the association with lesion growth remains unclear …”

“…[5][6][7] The relationship between lesion growth and electrogram diminution has not been studied in detail until the recent introduction of microelectrode (ME) embedded catheters. [8][9][10] Impedance decrement during ablations is another metric used to guide ablation time, and has been studied extensively for its usefulness as a surrogate marker for effective lesion formation and also to predict complications; however, the association with lesion growth remains unclear. [11][12][13][14] The direct endocardial visualization (DEV) catheter provides a unique opportunity to observe lesion formation in real time while recording electrogram amplitude and impedance during in vivo ablation.…”

Catheter ablation of ventricular arrhythmias

“…Initial data with this tool demonstrates improved EGM resolution with an ability to detect gaps in the ablation line [60]. Multiple diagnostic catheters with tight spacing have been used for this purpose.…”

Use of microelectrode near‐field signals to determine catheter contact

“…The development of an ablation catheter with miniature electrodes embedded in a radial fashion at the tip of the catheter (IntellaTip MiFi ® , Boston Scientific, Natick, MA, USA) may improve assessment of tissue‐electrode contact by recording ultra‐near‐field EGMs and attenuating far‐field components of the signal. Prior work has demonstrated significant differences in EGM characteristics between standard electrograms (sEGM) recorded from the distal bipole of the ablation catheter and microelectrode EGMs (mEGM) and has suggested a correlation between mEGM amplitude differential and contact force . However, characteristics of mEGM signals which best correlate with tissue‐electrode contact and the sensitivity of mEGM signals for determining contact have not been well characterized.…”