4.3 The LAPW myocardium and the fat pad
No relationship was found between the LA diameter, age, gender, BMI,
type of AF (PAF or PsAF), and the thickness of the LAPW myocardium under
CPL and MPL. The thickness of LAPW myocardium could vary from different
measurements. A cadaver study reported the
myocardium was thicker in the
inferior region (close to coronary sinus) than in the middle region
(close to inferior PV), and the roofline region was the
thinnest.13 This result
was comparable with our study in which we also observed that the
myocardium inferior PV region corresponded to the lower region of MPL,
while the middle region corresponded to the region of CPL. From the CT
study, however, Lemola et
al12 reported that the
thickness of LAPW myocardium was 2.2 ± 0.9mm with no difference from
superior to inferior regions. Suenari et
al19 reported that in
cases where there were close contacts between the esophagus and left PV
atrium, the distance was about 1.79 ± 0.22mm. These measurements
indicated that the LAPW musculature was quite thin in the inferior
PV region. Indeed, the thickness
of LAPW myocardium in the region of CPL almost represents the distance
between the endocardium of LAPW and the
esophagus,11 because a
lower fat pad is presented between the CPL and the esophagus. It was
reported the fat pad was mainly located in the superior and inferior
part of LAPW19 and it
was thinnest at the level between the orifices of the inferior
PV13 where the CPL was
located. Consistent with our study, only 18.6% of CPL with a fat pad
was observed, whereas 74.5% of MPL with a fat pad was noticeable.
Therefore, the higher presence of a fat pad in the MPL might serve as a
protection of esophageal ablation injury.