Discussion
The left PV obstruction caused by compression between the LA and the DA
has been rarely reported 2-5,11. Previous reports
demonstrate that the left lower PV is usually involved, and four out of
five patients exhibited left lower PV obstruction in the present study
as well. Some of the possible factors that affect the left PV
obstruction caused by compression between the LA and the DA should be
considered. First, the abnormally anterior location of the DA can be a
cause. The left PV can be narrowed due to compression from the back by
the DA located forward 2. The PV has clearly low
pressure as compared to the DA. Therefore, if the anteriorly located DA
passes just behind the PV, it can cause narrowing of the involved PV.
Second, an enlarged LA can compress the left PV from the front in the
space between the LA and the DA. This phenomenon can be observed in the
heart with left-sided volume loading, such as atrioventricular valvular
(AVV) regurgitation or large left-to-right shunt lesions4,5. The third possible factor can be a cardiac
compression that is seen posteriorly due to chest wall deformity such as
the pectus excavatum
Direct surgical repair 13-15, balloon dilatation16,17, and stent implantation 18,19can be the treatment options for the PV obstruction caused by
compression between the LA and the DA. Kotani et al. reported 15
patients with left PV obstruction among 494 consecutive
single-ventricular patients. The authors performed the sutureless repair
in seven patients and failed to achieve the Fontan operation. Posterior
aortopexy was not attempted in any of the patients 4.
O’Donnell et al. reported 29 cases (1.5%) of 1995 patients who
underwent hemodynamic catheterization. Of these, 26 had a left aortic
arch and a left lower PV compression, and three had a right aortic arch,
right-sided descending aorta, and a right lower PV compression. Nineteen
of 29 patients had a single-ventricular physiology. The authors
performed PV stenting in two patients who had single ventricular
physiology with poor results. Other surgical interventions for relief of
PV obstruction including posterior aortopexy were not performed in any
of the patients 5. We had a case of successful relief
from PV obstruction with a posterior aortopexy in a post-Fontan patient
(patient 1). Kotani et al. reported a case of successful relief from the
left PV obstruction by posterior aortopexy and plication of a redundant
LA wall in a patient with the complete atrioventricular septal defect
and persistent left superior vena cava. The posterior aortopexy
technique for patients with PV obstruction caused by compression between
the LA and the anteriorly positioned DA has several advantages as
mentioned earlier by Kotani et al. 3. First, external
compression of the PV by the anteriorly positioned DA could be
effectively treated. Second, the posterior aortopexy technique is a less
invasive procedure as compared to the intra-cardiac repair of the PV
under cardiopulmonary bypass. Third, avoiding direct surgical
manipulation of the PVs could prevent post-repair PV stenosis.
Using the posterior aortopexy technique we have treated five patients
with left PV obstruction between the LA and the DA. In two patients
(Patient 1 and 3) with focal PV obstruction that was mainly caused by
the anterior location of the DA, posterior aortopexy was effectively
performed. The changes in the angle between the DA and the vertebra
(ㅿa) were 37 and 38, respectively. In the patients with LA enlargement
caused by left heart volume loading (Patient 4 and 5), the effectiveness
of the posterior aortopexy was somewhat unclear. In patient 4, the
improvement in the left PV obstruction occurred immediately after the
operation. This improvement can be attributed to either posterior
aortopexy (ㅿa = 20) or decreased blood flow to the left lung or both of
them. In the case of patient 5, posterior aortopexy was not effectively
performed (ㅿa = -1). The improvement in the left PV obstruction
observed in patient 5 was thought to be due to the reduction in the
volume loading of the heart by the PDA ligation. Finally, in patient 2,
a preoperative CTR was 0.66. The left PV obstruction did not improve
after the posterior aortopexy. In this patient, diffuse left PV
obstruction was observed. The immediate postoperative CTR was still
0.64, showing the cardiomegaly, and the postoperative PG across the left
lower PV was 20 mmHg. The cause of the left PV stenosis could be an
intrinsic diffuse PV stenosis.
Based on our experiences with the five patients, it is hypothesized that
posterior aortopexy is an effective option for the management of the PV
obstruction caused mainly by the anterior location of the DA in the
patients without left heart volume loading. However, the effectiveness
of posterior aortopexy is somewhat unclear in patients with severe left
heart volume loading. A sudden decrease in left lung blood flow can mask
the effectiveness of the posterior aortopexy.
Our current study has some clear limitations. It is a retrospective
study investigating a small number of patients with heterogeneous heart
diseases, and there were no definite operative indications for the
procedure. Also, we measured the CTR to evaluate the volume loading and
enlarged LA of the patients, but it is not enough to show them
sometimes. Moreover, the definition of focal and diffuse stenosis is not
clear. To overcome these limitations, we performed preoperative and
postoperative CT angiography for all 5 patients.
In conclusion, posterior aortopexy could be considered as an effective
treatment option for patients with left PV obstruction that is mainly
caused by the anterior location of the DA without the left heart volume
loading. In patients with large left heart volume loading, the posterior
aortopexy could be recommendable in cases where PV obstruction persists
even after removal of the volume loading.