High-Resolution Mapping of Ventricular Scar

Abstract

Background Mapping resolution is influenced by electrode size and interelectrode spacing. The aims of this study were to establish normal electrogram criteria for 1mm multielectrode-mapping catheters (Pentaray®) in the ventricle and to compare its mapping resolution within scar to standard 3.5mm catheters (Smart-Touch Thermocool®). Methods and Results Three healthy swine and 11 swine with healed myocardial infarction underwent sequential mapping of the left ventricle with both catheters. Bipolar voltage amplitude in healthy tissue was similar between 3.5mm and 1mm multielectrode catheters with a 5th percentile of 1.61mV and 1.48mV, respectively. In swine with healed infarction, the total area of low bipolar voltage amplitude (defined as <1.5mV) was 22.5% smaller using 1mm multielectrode catheters (21.7cm2 versus 28.0cm2; p=0.003). This was more evident in the area of “dense scar” (bipolar amplitude <0.5mV) with a 47% smaller very low voltage area identified using 1mm electrode catheters (7.1cm2 vs. 15.2cm2; p=0.003). In this region, 1mm multielectrode catheters recorded higher voltage amplitude (0.72±0.81mV vs. 0.30±0.12mV, p<0.001). Importantly, 27% of these “dense scar” electrograms showed distinct triphasic electrograms when mapped using a 1mm multielectrode catheter compared with fractionated multicomponent electrogram recorded with the 3.5mm electrode catheter. In 8 mapped reentrant VTs, the circuits included regions of preserved myocardial tissue “channels” identified with 1mm multielectrode catheters but not 3.5mm electrode catheters. Pacing threshold within the area of low voltage was lower with 1mm electrode catheters (0.9±1.3mV vs. 3.8±3.7mV, p=0.001). Conclusions Mapping with small closely spaced electrode catheters can improve mapping resolution within areas of low voltage.

Myocardial Scar Delineation Using Diffusion Tensor Magnetic Resonance Tractography

“…Regions of the LV with a PA ≤4 consistently had a bipolar voltage ≥1.5 mV, those with PA values between 4 and 10 had voltage between 0.5 and 1.5 mV, and those with a PA >10 had voltage ≤0.5 mV. These are congruent with generally accepted definitions of normal myocardium (≥1.5 mV), border zone (0.5–1.5 mV), and dense scar (≤0.5 mV) by bipolar voltage mapping 9, 31. Furthermore, these intermediate voltage and PA values are consistent with the intermediate values seen in gray‐zone LGE 2, 3, 4, 30…”

“…Each segment of the tractograms was then color‐coded by endocardial bipolar voltage based on the nearest mapping point. We used endocardial bipolar voltage values to delineate normal myocardium (≥1.5 mV) from dense scar (≤0.5 mV) and border zone (0.5–1.5 mV) 9, 31. The relationship between PA and bipolar voltage was nonlinear and was modeled using both a rational polynomial function of the form, V (PA) =a+[b/(PA c +d)], and a piecewise linear model.…”

“…Myocardial tissue characterization is also of value in the diagnosis and assessment of a number of nonischemic cardiomyopathies 5, 6, 7. In addition, scar‐imaging techniques are increasingly used in the preprocedural assessment of the underlying arrhythmic substrate for patients undergoing catheter ablation for ventricular arrhythmias,8 for which intraprocedural scar definition is performed using endocardial or epicardial voltage mapping 8, 9…”

Atrial tachycardia related to local abnormal atrial activity

“…Mapping using the PentaRay ® NAV catheter, with a 1 mm tip and 2 mm spaced electrodes, has been described to improve the mapping resolution within areas of low voltage 3. The small and narrow spaced electrode catheters allowed for recording the fine potentials that were missed with the larger electrodes.…”

Catheter ablation of hemodynamically unstable ventricular tachycardia in ischemic cardiomyopathy using high‐resolution mapping

“…Both available approaches, a basket catheter and another multielectrode‐mapping catheter (e.g. PentaRay ® ), might provide more accurate maps with high resolution in comparison with classical concepts, especially in low‐voltage areas 11. On the other hand, both can produce premature ventricular contractions especially in the left ventricle what can impact the mapping itself.…”