case_images: PMC10794817_01
case_images: Activation and entrainment maps of atrial flutter of our case in left atrium. (A) Activation map showing the peri-mitral atrial flutter pattern, with a conduction gap in the mitral isthmus. Local activation time was only 200 ms of 265 ms (75%). Post-pacing interval-cycle lengths indicated 0, 5, 0, 30, 40, and 40 ms at the 12 o'clock position of mitral valve annulus (site 1), 4 o'clock position of mitral valve annulus (site 2), 2 o'clock position of mitral valve annulus (site 3), left pulmonary vein upper ridge (site 4), left pulmonary vein lower ridge (site 5), and vein of marshall 3-4 electrode on the endocardial block line in mitral isthmus (tag: site 6), respectively. radiofrequency ablation was performed at the left pulmonary vein ridge, left atrial appendage base, and mitral isthmus, as indicated by the red ablation tag. (B) Activation map of the centrifugal pattern from the 4 o'clock position of the mitral valve annulus.
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case_images: PMC10794817_01_ytad598f1.jpg
case_images: ytad598-F1
case_images: However, the MI line indicated a conduction block on the endocardial side (Figure 1A) and a centrifugal pattern on the 4 o'clock of the mitral valve annulus (MVA) (Figure 1B). A 1.8-Fr catheter (EP Star, Lifeline, Tokyo, Japan) was inserted into the vein of marshall (VOM) using the femoral approach, and an entrainment map was created at various locations as follows: The post-pacing interval-cycle length (PPI-CL) values were 0, 5, 0, 30, 40, and 40 ms at the 12 o'clock position of the MVA, 4 o'clock position of the MVA, 2 o'clock position of the MVA, LPV upper ridge, LPV lower ridge, and VOM 3-4 electrode on the endocardial block line in the MI, respectively (Figure 1A, site 1-6). When radiofrequency energy (40 W, 30-60 s) was applied, as shown in Figure 1A, cycle length prolongation without a change in the conduction sequence was observed (from 265 to 400 ms), although the AFL did not terminate.
case_images: Cryoballoon ablation to the mitral isthmus and intracardiac electrocardiogram at the termination of the atrial flutter. (A) An eight-electrode mapping catheter is anchored into left inferior pulmonary vein, and the northern hemisphere of the cryoballoon is directed towards the mitral isthmus for ablation (freezing time: 180 s, minimum nadir balloon temperature: -38 C). (B) The steerable sheath is bent approximately 90  to the left atrial appendage base for the second ablation (freezing time: 180 s, minimum nadir temperature: -38 C). (C) The steerable sheath tip is bent downward, and the cryoballoon is gradually released. The sheath is subsequently unbent while pulling it downwards, and the northern hemisphere of the cryoballoon is directed towards the annulus side of the mitral isthmus. (D) The northern hemisphere of the cryoballoon is crimped to the annulus side of the mitral isthmus (freezing time: 180 s, minimum nadir balloon temperature: -37 C). (E) The left side shows an intracardiac electrocardiogram before the second cryoballoon ablation, and the cycle length is 400 ms. The right side shows an intracardiac electrocardiogram at the termination of atrial flutter during the second cryoballoon ablation to the left atrial appendage base.
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case_images: PMC10794817_01_ytad598f2.jpg
case_images: ytad598-F2
case_images: First, an eight-electrode mapping catheter (ACHIEVE ADVANCE mapping catheter, Medtronic, Dublin, Ireland) was anchored into the left inferior PV (Figure 2A), and the northern hemisphere of the cryoballoon (Arctic Front Advance pro, Medtronic) was directed towards the MI for ablation (freezing time: 180 s, minimum nadir balloon temperature: -38 C). Subsequently, the catheter was pulled to the balloon tip, and the steerable sheath (FlexCath Advance, Medtronic) was bent approximately 90  to the left atrial appendage base for second ablation (freezing time: 180 s, minimum nadir temperature: -38 C) (Figure 2B). Since the northern hemisphere of the cryoballoon could not target the MI annulus side using similar catheter orientation as in the first and second CBA procedures, a third CBA was performed by bending the steerable sheath tip down and pulling the sheath downward while unbending and crimping the northern hemisphere of the cryoballoon to the MI annulus side (freezing time: 180 s, minimum nadir balloon temperature: -37 C) (Figure 2C and D). During the second CBA, the cycle length was prolonged and terminated (Figure 2E).
case_images: Pre-voltage and post-voltage maps. The left and right panels show the pre-voltage and post-voltage maps, respectively. In the post-voltage map, a homogeneous low-voltage area was extensively created in the mitral isthmus area.
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case_images: PMC10794817_01_ytad598f3.jpg
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case_images: Postmapping was performed, confirming wide and uniform lesion formation in MI area (Figure 3).