Myocardial work efficiency in children with Wolff-Parkinson-White preexcitation before and after accessory pathway ablation

Figures

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  Figure 1. A flowchart of the enrollment process. AP, accessory pathway; LV, left ventricular; WPW, Wolff-Parkinson-White.

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  Figure 2. Myocardial work analysis in a patient with WPW syndrome and left inferolateral AP. The bull's eye plot represents LV myocardium divided into individual segments and shows: (A) Segmental values of MWI in mmHg%; (B) Values of MWE in %; (C) Global LV pressure-strain loop (red) and pressure-strain loop representing the segment at ventricular AP insertion (green), where pressure-strain loop area from mitral valve closure to mitral valve opening stands for performed myocardial work, as explained further in the text (see Methods). Major decrease of both MWI and MWE along with a distorted pressure-strain loop is evident in segments adjacent to AP. (D) Graphical presentation of the methodology of MWI, MCW and MWW calculations (30). *Annotation of segmental distance from ventricular accessory pathway AP insertion. ANT, anterior; ANT-LAT, anterolateral; ANT-SEPT, anteroseptal; AP, accessory pathway; AVC, aortic valve closure; AVO, aortic valve opening; INF, inferior; INF-LAT, inferolateral; INF-SEPT, inferoseptal; LV, left ventricular; LVP, left ventricular pressure; MVC, mitral valve closure; MVO, mitral valve opening; MWE, myocardial work efficiency; MWI, myocardial work index; WPW,…

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  Figure 3. Accessory pathway location. The numbers in parentheses indicate the count of accessory pathways in each location as they occurred in the study population. ANT, anterior; ANT-LAT, anterolateral; ANT-SEPT, anteroseptal; INF, inferior; INF-LAT, inferolateral; INF-SEPT, inferoseptal; LAT, lateral. Figure 3 was created by the first author.

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  Figure 4. Global myocardial work efficiency and the degree of preexcitation in patients with WPW preexcitation before ablation. The degree of preexcitation was expressed as the duration of QRS complex and the interval from the earliest delta wave onset to R wave peak in V6. Relationship between the two variables was evaluated using linear regression A. MWE vs. QRS duration. B. MWE vs. delta to R peak interval in V6. LV, left ventricular; MWE, myocardial work efficiency; WPW, Wolff-Parkinson-White. Figure 4 was created in the SigmaPlot statistical software (see the statistics section), labels were added in MS PowerPoint.

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  Figure 5. Segmental data before and after ablation of left inferolateral AP. Myocardial work efficiency, global LV pressure-strain loop (red) and segmental pressure-strain loop from the ventricular AP insertion site (green) before (A) and (B) and after (C) and (D) AP ablation. The area under the pressure-strain loop corresponds to the MWI. Normalization of both the segmental loops and segmental MWE at the AP insertion is seen after ablation. ANT, anterior; ANT-LAT, anterolateral; ANT-SEPT, anteroseptal; AP, accessory pathway; AVC, aortic valve closure; AVO, aortic valve opening; INF, inferior; INF-LAT, inferolateral; INF-SEPT, inferoseptal; LV, left ventricular; LVP, left ventricular pressure; MVC, mitral valve closure; MVO, mitral valve opening; MWE, myocardial work efficiency; MWI, myocardial work index. Figure 5 consists of screenshots from the EchoPAC platform (see the echocardiography section).

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  Figure 6. Segmental data and the distance from AP insertion. LV segmental time to peak longitudinal strain and myocardial work efficiency expressed as a function of the distance from ventricular AP insertion in patients with a single left free wall or paraseptal AP before [(A) and (B); N = 28] and after [(C) and (D); N = 23 patients] ablation. X axis denotes the respective segmental distance from ventricular pathway insertion (0, identical segment; 1, neighboring segment; 2, one interposed segment; 3, two interposed segments (see Figure 2*)). Analysis limited to patients with single left free wall and paraseptal pathways. The difference between individual segments was evaluated using ANOVA. AP, accessory pathway; LV, left ventricular; NS, nonsignificant. Figure 6 was created in the SigmaPlot statistical software (see the statistics section), labels were added in MS PowerPoint.

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  Figure 7. Myocardial work efficiency in segments (N = 23 patients, N = 153 segments) adjacent to ventricular AP insertion (segments 0 and 1, see methods) before and after ablation. AP, accessory pathway; MWE, myocardial work efficiency. Figure 7 was created in the SigmaPlot statistical software (see the statistics section), labels were added in MS PowerPoint.

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  Figure 8. Bland-Altman plots describing inter-observer variability in segmental myocardial work parameters. CI, confidence interval; MCW, myocardial constructive work; MWI, myocardial work index; MWE, myocardial work efficiency; MWW, myocardial wasted work; Std Dev, standard deviation. Figure 8 was created in the SigmaPlot statistical software (see the statistics section), labels were added in MS PowerPoint.