Functional characterization of the crista terminalis in patients with atrial flutter: implications for radiofrequency ablation
Tu-Ying Liu, MD* ,
Ching-Tai Tai, MD* ,*,
Bien-Hsien Huang, MD,
Satoshi Higa, MD,
Yenn-Jiang Lin, MD*,
Jin-Long Huang, MD*,
Yoga Yuniadi, MD,
Pi-Chang Lee, MD*,
Yu-An Ding, MD* and
Shih-Ann Chen, MD*
* National Yang-Ming University School of Medicine, Taipei, Taiwan
Division of Cardiology, Department of Medicine, Chutung Veterans Hospital, Chutung, Taiwan
Taipei Veterans General Hospital, Taipei, Taiwan
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Figure 1 Propagation maps during typical atrial flutter (AFL) and upper loop re-entry (ULR). The non-contact mapping in Case 6 is displayed. (A) The propagation map of typical AFL in the right posterolateral view is shown on the left. The unipolar virtual electrograms are shown on the right. During clockwise typical AFL, the activation wavefront descends in the right atrium (RA) posterior wall and septum (a to c), travels through the cavotricuspid isthmus (not shown), and ascends in the RA anterior and lateral walls (d to f). Virtual electrograms along the crista terminalis (CT) show double potentials resulting from different wavefront propagation direction on each side of the CT. (B) The propagation map of ULR in the same patient is shown. The activation wavefront propagates down in the posterior RA (a to b), crosses a conduction gap in the CT (b to c), proceeds upward in the anterolateral RA, and turns around the superior vena cava (c to d) to complete the re-entrant circuit (d to a). Virtual electrograms (Virtual 9) on the CT show low amplitude potential between the first and second deflection, suggesting the presence of a conduction gap. IVC = inferior vena cava; SVC = superior vena cava.
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Figure 2 Measurement of conduction velocity. The propagation map and the virtual electrograms demonstrate the measurement of longitudinal conduction velocity in Case 6. Propagation of the activation wavefront is shown on the left. The surface distance (D) is measured between the first and the last virtual locations. On the right, the virtual unipolar electrograms are displayed. Time interval (T) between the first and the last peak negative deflections in the virtual unipolar electrograms is measured. The conduction velocity is calculated using the surface distance divided by time interval (D/T).
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Figure 3 (A) The measurement of the width of the crista terminalis (CT) gap. During animation of the isopotential map while the activation wavefront propagates through the gap, the contour lines of voltage converge and turn as they pass the edge of the CT gap. The location adjacent to the convergence of the isopotential contour lines is defined as the edge of the gap. Therefore, the width of the CT gap is measured as the surface distance between the edges of the gap. (B) The propagation of activation wavefront across the CT conduction gap in Case 6. The marked blue line represents the measurement of the width of the CT gap.
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Figure 4 The relationship between the anisotropic ratio (CVL/CVT) and the width of the crista terminalis (CT) gap. The distribution of the anisotropic ratio of longitudinal/transverse conduction velocities (Y-axis) and the width of crista gap (X-axis) are plotted, showing the inverse relationship between anisotropic ratio and the width of the CT gap. CVL = longitudinal conduction velocity; CVT = transverse conduction velocity.
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