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

Figures

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  Fig 1. Illustration of the segmentation method for electroanatomical left ventricular voltage map analysis during sinus rhythm. (A) Color-coded areas of dense scar (< 0.2 mV, red), scar border zones (0.2–1.0 mV, yellow, green and blue) and healthy myocardium (> 1.0 mV, purple) are displayed in a patient with prior myocardial infarction and scar-related ventricular tachycardia undergoing catheter ablation. (B and C) The 17-segment-model was applied to the 3-dimensional map and 2- dimensional polar plot for further analysis of the localization of set ablation lesions (white points). The clinically documented VT was induced (cycle length 500 ms) and successfully terminated by ablation. The mean EGM duration and mean voltage value based on all EGM per segment (for example red points in segment 7) was calculated. Correlation between voltage, EGM duration and ablation were conducted segment by segment.

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  Fig 2. Method and schematic visualization of electrogram duration estimation using sliding SD-window and SD-threshold. (A) Visualization of filtered electrogram with its sample points (red dots) recorded with bipolar electrodes from a single beat. Sample points with corresponding local voltage are displayed at a rate of 1 millisecond (left). Magnification of the labelled interval (right). A sliding standard deviation (SD) window was applied to calculate SD over a moving window (black box) of predefined length across neighboring sample points. The dotted box indicates the method of consecutive SD value determination. (B) The corresponding SD values generate the SD-curve for further signal processing (left). Magnification of the labelled interval (right). The calculated SD value corresponds to a specific time unit (red box) in the moving window and is transformed into SD-curve. (C) Schematic visualization of workflow of signal processing parameter estimating EGM duration. After extraction of the raw bipolar electrogram during sinus rhythm (1), a bandpass filter of 30–250 Hz was applied (2). A sliding SD-window of 40 ms length calculates the SD across the electrogram (3). Onset and offset…

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  Fig 3. Visualization of Effects on electrogram duration estimation using various sliding SD-window and SD-threshold during sinus rhythm. Estimation of electrogram (EGM) duration decreases with rising SD-threshold: At SD-threshold = 10%, EGM duration is overestimated, whereas at SD-threshold = 30% EGM duration is underestimated by using constant SD-window size of 20 ms. Estimation of EGM duration increases with rising sliding SD-window: At sliding SD-window = 15 ms, EGM duration is underestimated, whereas at sliding SD-window = 35 ms EGM duration is overestimated by using constant SD-threshold of 25%.

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  Fig 4. Diagnostic odds ratio color-coded maps demonstrate validation of signal processing parameters. According to the highest diagnostic odds ratio (DOR) value, the signal processing parameters sliding SD-window (test range: 10–45 ms) and SD-threshold (test range: 0.1–0.5) are validated. The color-coded scale represents linear interpolation of DOR, with yellow being the highest and blue the lowest. (A) The parameter sets 35/10/65 and 40/20/65 (SD-window size/SD-threshold/EGM duration cutoff) result in a DOR of 10.11. (B) The parameter set 40/15/70 results in the highest DOR of 12.77 (red asterisk). This parameter set leads to a DOR of 12.77, describing a 12.77-times higher probability that ablation points were set in areas with a mean EGM duration > 70 ms compared to areas with an EGM duration ≤ 70 ms (95% Cl: 3.0848–56.1523, P = 0.0005). (C) The parameter set 35/10/75 results in a DOR of 8.19. (D) The parameter set 40/10/80 results in a DOR of 5.53.

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  Fig 5. Image integration of a left ventricular 3-D-electroanatomical voltage and electrogram duration map into the 17-segment model. (A) Left ventricular 3-dimensional voltage map (left) and 3-dimensional electrogram (EGM) duration map (right) in a patient with scar-related ventricular tachycardia during sinus rhythm demonstrating that majority of ablation points (white points) were performed in areas with dense scar (red), scar border zone (yellow, green and blue) and long EGM duration (purple). The clinical documented VT was induced (cycle length: 320 ms) and terminated by ablation. (B) Electro-anatomical 2-dimensional polar plot translation of voltage map (left) and electrogram duration map (right) demonstrating the feasibility of automated EGM duration-based identification of low voltage (< 1 mV) areas and ablation targets in segments 12,13,16 and 17.