Foxall, Thomas

Background: Ablation in the sinuses of Valsalva (SoV) within the aorta is fraught with risk, owing to the proximity of the coronary arteries. Assessment of catheter tip position is not very easy at this location owing to complex local anatomy and poor images from available modalities. Objectives: We propose the use of novel local unipolar electrogram characteristics using a new signal recording system to guide the assessment of catheter tip position in this region. Methods: We recorded unipolar signals from above the SoV, within the coronaries and below the SoV using the PURE-EP™ (BioSig Technologies, MN) signal processing system in 4 anesthetized canines in the setting of an acute study. We used fluoroscopy, intracardiac echocardiography and angiography for confirmation of the position of the catheter tip. We recorded changes in the signals when transitioning between (1) the coronary arteries and the SoV and (2) the SoV and below the SoV. Results: The unipolar signal showed a negative current of injury (COI) when the catheter tip was present in the SoV, whereas within the coronary artery or below the SoV, the COI was positive. We propose that the difference in the distribution of ventricular muscle below and above the SoV is responsible for this phenomenon. These changes in the COI were noted immediately when transitioning from one location to another and were present reproducibly in all the dogs. ( Figure 1 ) Conclusions: Analysis of the changes on the local electrogram can provide information about the location of the catheter tip which could prove critical in saving lives.