Detection of the diastolic pathway, circuit morphology, and inducibility of human postinfarction ventricular tachycardia from mapping in sinus rhythm

Abstract

Aims-We sought to determine whether sinus rhythm activation maps could be used to detect the origin and characteristics of reentrant ventricular tachycardia in postinfarction patients.Method-In each of 11 post-MI patients, unipolar electrograms were acquired at 256 virtual endocardial sites using non-contact mapping. Electrograms were marked for activation time and mapped on a three-dimensional grid. Spatial differences in sinus-rhythm activation time were correlated to isthmus characteristics, and to activation through the diastolic pathway during tachycardia, based on presence of contiguous lines of slow conduction and block.Results-Twenty tachycardia morphologies were analyzed. Fourteen sustained reentrant circuit morphologies occurred in 9 patients, with dual morphologies having a shared isthmus occurring in 5/9. Dual morphologies were caused by changes in entrance-exit point location about a common isthmus. One transient circuit morphology of <10 beats occurred in 3/9 patients also having sustained reentry. The estimated isthmus determined from sinus rhythm activation overlapped the diastolic pathway determined from tachycardia maps with 83.8% sensitivity and 89.2% specificity. Mean difference in sinus rhythm activation time across the isthmus border was larger in transient as compared to sustained morphologies (32.8±9.5ms versus 22.8±1.8ms), with smaller isthmus size (4.8±1.1cm 2 versus 10.0±1.1cm 2 , p<0.05) narrower entrance-exit points (7.0±1.5mm versus 9.3 ±0.8mm, p<0.05), and greater activation time difference across them (16.3±3.5ms versus 10.1 ±1.0ms, p<0.05).Conclusion-In post-MI patients, the reentry isthmus can be localized in the endocardial border zone from sinus rhythm activation maps. Nonsustained reentry occurs when isthmus size is small and entrance-exit points are narrow and more electrically discontinuous.

Evolution of Ventricular Tachycardia and Its Electrophysiological Substrate Early After Myocardial Infarction

“…This early stabilization is consistent with postmortem and animal MRI studies. 17,18 Our finding of multiple VT morphologies showing the same earliest activation site is consistent with Ciaccio et al, 19 who localized the re-entry isthmus in patients with chronic postinfarct VT and found that multiple VT morphologies shared isthmuses in most patients. In chronic postinfarct VT, the median number of inducible arrhythmias was 3, which is consistent with our findings at both time periods.…”

Model of Bipolar Electrogram Fractionation and Conduction Block Associated With Activation Wavefront Direction at Infarct Border Zone Lateral Isthmus Boundaries

“…27 However, fewer fractionated electrogram sites can be detected during sinus rhythm because of, in part, the slower activation rate 19 and because wavefront propagation may sometimes be oriented in the direction thick-to-thin across the LBs, which would not result in a discontinuous wavefront (Figure 1). …”

A Case of Radiofrequency Catheter Ablation of Ventricular Tachycardia Associated with an Old Myocardial Infarction Guided by a Noncontact Mapping System

“…The NCM has several potential advantages over conventional mapping techniques, in which a 3-dimentional beat-tobeat activation analysis can be performed with a high resolution of >3000 endocardial points, but some concerns have been raised in terms of the reliability of the virtual unipolar electrograms at remote points of >4:0 cm from the center of the MEA, weak resolution capability of the low frequency/amplitude electrograms, and influence of the repolarization on the interpretation of real potentials. However, recent studies have demonstrated the safety and usefulness of the NCM for the mapping and ablation of VT associated with an OMI, 1,2,[10][11][12] in which the NCM was considered useful even in patients with hemodynamically unstable and/or nonsustained VTs. 13) The significance of the DSM for elucidating the low voltage zones is becoming recognized.…”