Introduction: Phrenic nerve (PN) injury is a rare but severe complication of radiofrequency (RF) pulmonary vein isolation (PVI).
Objective: To characterize the typical intracardiac course of the PN with a three-dimensional electroanatomic mapping system, quantify the need for modification of the ablation trajectory and estimate a safe distance for an ablation procedure.
Methods: We prospectively enrolled 137 consecutive patients (63±9 years, 64% men) undergoing PVI. A detailed high output (20 mA) pace-mapping protocol was performed in the right (RA) and left atrium (LA) and adjacent vasculature.
Results: The right PN was most commonly captured in the superior vena cava (SVC) at a lateral (50%) or posterolateral (23%) position prior to descending along the RA either straight (29%) or with a posterolateral bend (20%). In the LA, beginning deep within the right superior pulmonary vein (RSPV), the right PN is most frequently detectable anterolateral (31%), then descends to the lateral proximal RSPV (23%), and further towards the lateral antral region (15%) onto the medial LA wall (12%). Due to immediate PN proximity, modification of ablation site was necessary in 23% of cases, most commonly in the lateral RSPV antrum (81%). No PN injury occurred by keeping a minimal distance of 5 mm. Procedure-time increased by 11.4 (9.5-13.5) minutes.
Conclusion: PN mapping frequently reveals the need for modification of the ablation trajectory during PVI particularly in the lateral RSPV antrum. Routine PN pacing should be considered during radiofrequency PVI procedures.
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Table 1: Clinical Parameters |
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n = 137 |
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Age (years) |
63 |
± 9 |
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Male gender |
88 |
64 % |
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Structural heart disease |
22 |
16 % |
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Coronary artery disease |
24 |
18 % |
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Arterial hypertension |
100 |
73 % |
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Diabetes mellitus |
14 |
10 % |
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Body mass index (kg/m²) |
29 |
± 4 |
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Atrial fibrillation type |
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- paroxysmal |
54 |
39 % |
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- persistent |
83 |
61 % |
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Data is
displayed as n (%) or mean ± SD
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Table 2: Procedural parameters |
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n = 137 |
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Re-do, n (%) |
45 |
33 % |
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Ablation lesion set, n (%) |
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- PVI |
88 |
64 % |
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- Re-PVI RSPV |
12 |
9 % |
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- Re-PVI RIPV |
7 |
5 % |
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- Re-PVI LSPV |
11 |
8 % |
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- Antral Re-PVI |
31 |
23 % |
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- Other |
2 |
2 % |
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Right atrial mapping time (min) |
6 |
(5 - 8) |
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RA PN Pacing time (min) |
3 |
(2 - 4) |
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Left atrial mapping time (min) |
12 |
(10 - 15) |
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LA PN Pacing time (min) |
2 |
(1,5 - 3) |
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Data is displayed as n (%) or median (IQR)
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Table 3: Phrenic nerve parameters |
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Right PN capture |
136/137 |
99 % |
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Left PN capture |
25/65 |
39 % |
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Max. distance RA - LA PNC High (mm) |
9 |
(6 - 10) |
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Superior vena cava |
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High output capture |
119/137 |
87 % |
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SVC: Length PNC line high (mm) |
20 |
(16 - 20) |
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Right atrium |
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High output capture |
85/137 |
62 % |
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RA: Length PNC line high (mm) |
39,5 |
(11,25 - 54) |
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RSPV with medial wall LA |
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High output capture |
78/137 |
57 % |
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RSPV/LA: Length PNC line high (mm) |
13 |
(6,5 - 22) |
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Left atrial appendage |
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High output capture |
25/65 |
39 % |
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LAA: Length PNC line high (mm) |
8 |
(4 - 13) |
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Data is displayed as n (%) or median (IQR)
Figure 1: View from a right medial position: Most common regions of right PNC in the (A) left atrium and (B) right atrium [n = 137].
Figure 2: Most common regions of (A) minimal distance between PNC and ablation site [n =74] and (B) necessitating modulation of the ablation trajectory [n = 31].
Figure 3: (A) View of the LA medial wall from a right medial position in a patient needing modification of the PVI ablation trajectory due to right PN course, (B) same patient additionally showing the RA highlighting the close spatial relationship of right PN course and both atria in selective patients.
https://dgk.org/kongress_programme/jt2022/aP1915.html