A novel algorithm for 3-D visualization of electrogram duration for substrate-mapping in patients with ischemic heart disease and ventricular tachycardia

Abstract

Background Myocardial slow conduction is a cornerstone of ventricular tachycardia (VT). Prolonged electrogram (EGM) duration is a useful surrogate parameter and manual annotation of EGM characteristics are widely used during catheter-based ablation of the arrhythmogenic substrate. However, this remains time-consuming and prone to inter-operator variability. We aimed to develop an algorithm for 3-D visualization of EGM duration relative to the 17-segment American Heart Association model. Methods To calculate and visualize EGM duration, in sinus rhythm acquired high-density maps of patients with ischemic cardiomyopathy undergoing substrate-based VT ablation using a 64-mini polar basket-catheter with low noise of 0.01 mV were analyzed. Using a custom developed algorithm based on standard deviation and threshold, the relationship between EGM duration, endocardial voltage and ablation areas was studied by creating 17-segment 3-D models and 2-D polar plots. Results 140,508 EGMs from 272 segments (n = 16 patients, 94% male, age: 66±2.4, ejection fraction: 31±2%) were studied and 3-D visualization of EGM duration was performed. Analysis of signal processing parameters revealed that a 40 ms sliding SD-window, 15% SD-threshold and >70 ms EGM duration cutoff was chosen based on diagnostic odds ratio of 12.77 to visualize rapidly prolonged EGM durations. EGMs > 70 ms matched to 99% of areas within dense scar (<0.2 mV), in 95% of zones within scar border zone (0.2–1.0 mV) and detected ablated areas having resulted in non-inducibility at the end of the procedure. Ablation targets were identified with a sensitivity of 65.6% and a specificity of 94.6% avoiding false positive labeling of prolonged EGMs in segments with healthy myocardium. Conclusion The novel algorithm allows rapid visualization of prolonged EGM durations. This may facilitate more objective characterization of arrhythmogenic substrate in patients with ischemic cardiomyopathy.

Ventricular Electrograms Duration Map to Detect Ventricular Arrhythmia Substrate: the VEDUM Project Study

“…Patients with a healthy ventricle myocardium have electrogram durations of < 70 ms as confirmed in a recent article. 15,16 Our data on electrogram duration are in accordance with the previous published data. 15,16 As reported in Figure 2, the electrogram durations of healthy tissue have a significantly shorter variability when compared with those recorded in the diseased areas (163.7 versus 65.5 ms; P <0.001).…”

“…15,16 Our data on electrogram duration are in accordance with the previous published data. 15,16 As reported in Figure 2, the electrogram durations of healthy tissue have a significantly shorter variability when compared with those recorded in the diseased areas (163.7 versus 65.5 ms; P <0.001). The high-density mapping catheter help to reduce the measurement bias due to the influence of the angle between the main vector of the wave-front propagation and the recording dipole.…”

Unlocking complex pathways in ventricular tachycardia: Ventricular abnormal activities detection mapping in a case of scar-related multiple ventricular tachycardias

“… 11 In the Rhythmia system (Boston Scientific, Marlborough, MA), the presence of prolonged electrogram durations has been identified as advantageous for substrate modification. 12 Both systems offer the capability to adjust the threshold for fractionation signals, aiding in substrate modification. In contrast, the “early meets late” function, exclusive to the CARTO system, enables the elucidation of local conduction delays as manifested in LAVAs, DP, and critical isthmuses by highlighting differences between local potentials.…”

Coronary Guidewires in Temporary Cardiac Pacing and Assessment of Myocardial Viability: Current Perspectives and Future Directions

“…Systematic experimental and clinical studies demonstrate that myocardial electrograms can differentiate non-viable from hibernating and normal myocardium on the basis of a lower amplitude in voltage, longer duration and fractionated electrograms [34][35][36][37][38][39][40][41][42][43][44]. Intracoronary electrograms (Ic ECG) (which will pick up myocardial signals) can be recorded with coronary guidewires.…”