Comparison of Electroanatomic Contact and Noncontact Mapping of Ventricular Scar in a Postinfarct Ovine Model With Intramural Needle Electrode Recording and Histological Validation

Abstract

Background-Substrate-based ablation is useful for nonhemodynamically tolerated postinfarct ventricular tachycardia. We assessed the accuracy of the CARTO contact and EnSite noncontact systems at identifying scar in a chronic ovine model with intramural plunge needle electrode recording and histological validation. Methods and Results-Scar mapping was performed on 8 male sheep with previous percutaneous-induced myocardial infarction. Up to 20 plunge needles were inserted into the left ventricle of each animal in areas of dense scar, scar border, and normal myocardium. A simultaneous CARTO map and EnSite geometry were acquired using a single catheter, and needle electrode locations were registered. A dynamic substrate map was constructed using ratiometric 50% peak negative voltage. The scar percentage around each needle location was quantified histologically. Analysis was performed on 152 plunge needles and corresponding histological blocks. Spearman correlation with histology was 0.690 (PϽ0.001) for needle electrode peak-to-peak voltage (PPV), 0.362 (PϽ0.001) and 0.492 (PϽ0.001) for CARTO bipolar and unipolar PPV, and 0.381 (PϽ0.001) for EnSite dynamic substrate map (Յ40 mm from array). The area under the receiver operator characteristics curve (Ͻ50% and Ն50% scar) was 0.896 for needle electrode PPV, 0.726 and 0.697 for CARTO bipolar and unipolar PPV, and 0.703 for EnSite dynamic substrate map (Յ40 mm from array). Conclusions-Both the CARTO contact and EnSite noncontact systems were moderately accurate in identifying postinfarct scar when compared with intramural electrodes and confirmed with histology. The EnSite dynamic substrate map was comparable to the CARTO contact bipolar PPV when points Ͼ40 mm from the array were excluded. (Circ Arrhythmia Electrophysiol. 2008;1:363-369.)

Recording and interpreting unipolar electrograms to guide catheter ablation

“…8 Unipolar electrograms have also been evaluated for substrate mapping. 9,[11][12][13][14] The amplitude of unipolar electrograms high-pass filtered at 1 Hz is threefold to fivefold greater than that of bipolar electrograms high-pass filtered at 30 Hz. In comparisons with infarct scars detected by magnetic resonance imaging, Codreanu et al 9 found that the best electrogram amplitude threshold for characterizing scar was 6.52 mV for unipolar electrograms and 1.54 mV for bipolar electrograms, and bipolar electrogram amplitude was a better discriminator of scar.…”

“…In an ovine infarct model, scar was better correlated with bipolar filtered as compared to unipolar minimally filtered electrogram amplitude. 12 At present, bipolar electrograms are preferred for defining endocardial scar.…”

Integration of 3D Electroanatomic Maps and Magnetic Resonance Scar Characterization Into the Navigation System to Guide Ventricular Tachycardia Ablation

“…Areas of interest show reduced EG amplitude in voltage maps and are considered a surrogate of myocardial scar. 2,3 An accurate high-density map of low voltage areas is key in identifying slow conduction zones inside the scar, also called conducting channels (CC). These CC display a higher voltage amplitude than the surrounding area and are the target for ablation in scar-related VTs.…”

Simultaneous Biventricular Noncontact Mapping and Ablation of Septal Ventricular Tachycardia in a Chronic Ovine Infarct Model

“…We have previously compared DSM with CARTO contact electrograms and validated the DSM scar localization with needle recordings and histology. 17 Use of DSM allows VT activation to be viewed over low-voltage substrate marked on the electroanatomic geometry, showing the relationship of the arrhythmic circuit to areas of scar. Generation of DSM is also faster than contact voltage maps because individual points do not require verification.…”