Reassessment of the electrical connection between the pulmonary veins and the left atrium: A study to determine the different contributions of myocardial fibers along the standard ablation circumference

Figures

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  Figure 1. Arrangement of myocardial fibers along the venoatrial junction in the left atrium. (A) Dissection showing a posterior view of the left atrium with transillumination to demonstrate the thinner sections. (B) A histological section in the transverse plane of a left-PV pair stained with Masson's trichrome technique to show variations in the widths of muscular fibers along the venoatrial junction. Note that myocardial fibers entering the carina are thicker (red arrows), while they are thinner and exhibit discontinuities in the superior and inferior aspects of the PV pairs (green arrows), especially on the left side. LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein; PVs, pulmonary veins; SVC, superior vena cava; IVC, inferior vena cava. Histological images provided courtesy of Dr. José Angel Cabrera.

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  Figure 2. Flowchart of the study ablation protocol.

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  Figure 3. Complete isolation of left and right-PV pairs after ablation of the anterior and posterior segments of the standard circumference around the ipsilateral PVs. Posterior and anterior views of the LA electroanatomical maps are shown. (A) High-density voltage map of the LA obtained before ablation. (B) The electroanatomical map is shown in gray with the RF lesions (ablation tags), delivered only in the anterior and posterior segments of the standard circumference around the ipsilateral PVs (yellow line), resulting in complete electrical isolation. (C) High-density voltage map acquired after PV isolation. Note that the low-voltage areas, consistent with electrical isolation, extend all around the ipsilateral PVs, including the upper and lower aspects of the PV pair, where ablation was not performed (ANRA).

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  Figure 4. Schematic representation illustrating the observations after ablation to the anterior and posterior segments of the standard circumference around the ipsilateral PVs. Ablation in these segments (orange dots) resulted in complete PV isolation of 77% left-PV pairs and 51% right-PV pairs. Horizontal dashed lines have been drawn to mark the equatorial level of the PVs. The green double-headed arrows show the extent of the areas non-requiring ablation at the time of PV isolation. ANRA, areas not requiring ablation; PVs, pulmonary veins; PVI, pulmonary vein isolation. ANRA length is expressed as median (IQR).

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  Figure 5. Example of ablation extension from the anterior and posterior segments guided by pacing from inside the connected PVs. A right lateral view of the right PVs that remained connected after ablation to the anterior and posterior segments of the standard circumference. The pacing was performed from the multipolar catheter inside the right-superior PV. Atrial activation next to the ablated segments was mapped using the ablation catheter. Note the earliest atrial activation identified at the superior end of the anterior ablated segment (thick yellow arrow), where two additional RF lesions led to complete PV isolation of both the superior and the inferior right PVs.

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  Figure 6. Schematic representation illustrating the observations at the end of the ablation protocol. As in Figure 4, horizontal dashed lines have been drawn to mark the equatorial level of the PVs, and the orange dots represent the initial set of RF lesions to the anterior and posterior segments of the standard circumference around the ipsilateral PVs. The blue and purple dots represent additional RF lesions in those patients requiring ablation extension from the anterior and posterior segments. The green double-headed arrows show the extent of the areas not requiring ablation at the time of PV isolation. ANRA, areas not requiring ablation; PVs, pulmonary veins; PVI, pulmonary vein isolation; SE, superior extension; IE, inferior extension. ANRA length is expressed as median (IQR).