The Anatomical Characteristics of Three Types of Left Atrial Linear Lines
: Potential Usefulness of Computed Tomography Before
Mitral Isthmus Line Creation and Atrial Fibrillation Ablation
Youngjin
1)
Cho ,
1)Department
Whal
2)
Lee ,
Eun-Ah
of Internal Medicine,
2)
Park ,
2)Radiology,
Il-Young
and
1)
Oh ,
Eue-Keun
3)Pathology,
1)
Choi ,
AM line
Since pulmonary vein (PV) isolation alone has not been
sufficient for the treatment of atrial fibrillation (AF),
the use of additional lesion creation has been
advocated. We evaluated the anatomical
characteristics of potential sites for additional linear
lesions during AF ablation.
AL line
A
A
PL line
Ao
LV
LV
LA
RSPV
LA
LA
LIPV
Fig 2. Representative MDCT images. Open arrows indicate sinus nodal artery
under the AM line (A) and LCx near the AL (B), PL line (C).
Ao, aorta; LA, left atrium; RSPV, rt. sup. PV; PM, anterolateral papillary muscle; LSPV, lt.
sup. PV.
Methods
Table 2
Subjects
- Multi-detector computed tomography (MDCT) data
from140 consecutive patients (40 paroxysmal AF).
- Heart specimens from 10 adult cadavers without
evidence of structural heart disease.
Definition of three mitral isthmus lines
Length†‡, mm
Depth of curve*†‡, mm
Max. thickness*†‡, mm
% distance from annulus*†‡
AM
49.4 ± 8.6
4.1 ± 1.5
2.1 ± 0.7
27 ± 14
AL
50.1 ± 7.2
7.8 ± 2.8
3.2 ± 1.0
47 ± 24
PL
36.4 ± 8.6
6.1 ± 3.0
2.4 ± 0.8
74 ± 22
*p<.05 in comparison between AM vs. AL, †between AM vs. PL, ‡between AL vs. PL line.
A
Cord-like structure on AM line
B
Diverticulum on PL
C
; potential sites for additional ablation
Fig 1. Schematic
MDCT images for
three types of mitral
PL isthmus lines.
Table 1
Mitral isthmus line
From
To
AM (anteromedial) line
Rt. sup. PV
10 o’clock of MA
AL (anterolateral) line
Lt. sup. PV
12 o’clock of MA
PL (posterolateral) line
Lt. inf. PV
4 o’clock of MA
MA; mitral annulus
Results
MDCT data (n=140)
- 40 paroxysmal AF (29%), 84 males (60%)
- Age; 59 ± 11 years
(white arrow
heads) of RCA
LA
Ao
LA
(open arrow)
runs to the
medial side of
RA
RA appendage
towards the
(B) SNA (black arrow heads) originates from LCx (open
arrow),
sinus
node
crossing both the AL and AM lines.
region.
Heart specimen data (n=10)
AM line
RSPV
AL line
MV
B
MV
PL line
LSPV
C
MV
LIPV
Ao
A
Fig 5. Representative photographs of human hearts incised at the three mitral
isthmus lines. (A) Cord-like structure (arrow heads), diverticulum (arrow), and
SNA (open arrow) were shown. (B) LCx (dotted circle) under the AL line. (C)
LCx and CV (dotted circle) near the PL line.
Table 5
AL
AM
B
RV
LSPV
PM
LV
Fig 4. 3D images
of SNA. (A) SNA
Ao
C
B
Seil
1)
Oh
Seoul National University Hospital, Seoul, Korea
Morphometric characteristics
Background
Jeong-Wook
3)
Seo ,
Fig 3. MDCT images of rough endocardial structures. (A) Cord-like
structure in 2D-planar and (B) in virtual endoscopic view, and (C)
diverticulum.
Table 3
AM
AL
PL
Endocardial obstacles*†‡
28 (20.0)
0 (0)
16 (11.4)
Cord-like structure (%)
Ridge*† (%)
Diverticulum*‡ (%)
4 (2.9)
0 (0)
0 (0)
12 (8.6)
0 (0)
0 (0)
11 (7.9)
0 (0)
16 (11.4)
*,†,‡ same as Table 2.
Adjacent vessels
Table 4
AM
AL
PL
134 (100)
62 (46.3)
13 (9.7)
2.5 ± 1.1
3.3 ± 1.7
2.3 ± 0.7
Distance to LCA‡, mm
-
5.8 ± 2.6
4.6 ± 3.5
Distance to CV‡, mm
-
9.0 ± 4.5
3.0 ± 1.0
SNA near the line*†‡§ (%)
Distance*, mm
*,†,‡ same as Table 2. § Six cases whose SNA could not be tracked down were excluded in
percent calculation. SNA, sinus node artery; LCA, left coronary artery; CV, cardiac vein.
Length, mm
Max. thickness, mm
% distance from annulus
Endocardial obstacles (%)
SNA near the line (%)
Distance to LCx, mm
AM
54 ± 7
4.3 ± 0.8
43 ± 10
2 (20)
9 (90)
-
AL
47 ± 16
5.0 ± 0.9
53 ± 13
0
3 (30)
-
PL
31 ± 6
3.9 ± 1.1
65 ± 11
0
0
5.2 ± 1.6
Conclusion
Among the three mitral isthmus lines, the PL lines wer
e shortest, but closest to the left coronary arteries. M
yocardium was thickest at the AL line, and SNAs were f
requently found on the AM and AL lines. Further studie
s with clinical outcomes after catheter ablation are re
quired to clarify the clinical impact of these anatomic
findings.
Disclosure: None.