4 | DISCUSSION
The purpose of the surgical treatment of FSV patient is to successful
achieve the Fontan circulation. Depending on the anatomy, patients with
single ventricle have four physiological modes, which are determined by
excessive or insufficient pulmonary blood flow, that are inadequate
pulmonary blood flow, excessive pulmonary blood flow with or without
systemic outflow obstruction, and balanced pulmonary blood
flow11. The primary goal of treatment for these
patients is to establish a stable pulmonary blood flow as early as
possible, and to avoid the adverse effects of continuous high blood flow
and high pressure on pulmonary vascular bed, so that the Fontan
circulation can be achieved in the later stage. Functional single
ventricle patients combined with TAPVC makes the surgical treatment more
complicated. Extracardiac TAPVC, especially with PVO, can cause
pulmonary hypertension which makes patients in a worse situation.
Surgical outcome of patients with FSV and TAPVC have a poor prognosis.
Therefore, urgent simultaneous or staged surgical intervention should be
performed in the infant stage or even the neonatal period. In our group
of cases, the patients with FSV and TAPVC who came to our center for
surgical treatment are all older. The median age were 32 months, range
from 2 to 256 months. We retrospectively analyzed mid-term results and
risk factors of petients with FSV and TAPVC in our center.
The management of patients with FSV and TAPVC remains challenging, a
rate of in-hospital death increase significantly and the overall
survival rate is low in this group6. Concomitant TAPVC
repair significantly increased the risk for mortality. It was reported
that operative mortalities of patients with FSV and TAPVC repair was
30% to 55%12,13, and the 5-year survival rate was
30%-60%2,4,10,14. Overall survival at 1 and 5 years
were 89.5% and 83.3%, respectively (Figure 2). One year survival is
58.3% in TAPVC repair group and 87.1% in non-TAPVC repair group. Three
years survival is 40% in TAPVC repair group and 87.1% in non-TAPVC
repair group (Figure 3). In our study, totally mortality rate in TAPVC
repair group was higher than that in non-TAPVC repair group (58.3% vs
12.9%, p = 0.002, HR:0.430) (Table 1). Type of TAPVC (p< 0.001) and preoperative PVO (p = 0.001) were
significant difference between these two groups. In our study,
univariate analysis identified that preoperative PVO (p = 0.047)
and concomitant TAPVC repair (p = 0.007) were risk factors for
mortality. Only concomitant TAPVC repair was risk factors for mortality
by multivariate analysis (Table 2).
Type of TAPVC also affects the prognosis of patients with FSV and TAPVC.
Nakayama Y and colleagues found that
subcardiac and mixed TAPVC influenced
the early surgical outcome of patients with FSV and TAPVC
repair7. Nakata T and colleagues identified mixed
TAPVC increased mortality of patients with FSV and TAPVC
repair14. In our study, intracardiac and supracardia
TAPVC are the main types of TAPVC (41/43, 95.3%). There are statistical
differences between the two groups in the type of TAPVC (p< 0.001) (Table 1), but it is not a risk factor affecting
mortality (Table 2). We consider that small proportion of mixed TAPVC
may be the main reason.
Pulmonary venous obstruction is another factor that increases risk of
mortality in patients with FSV and TAPVC1,7. Increased
pulmonary vascular resistance due to PVO is unfavorable for achieving a
successful Fontan circulation. Of 41 patients with FSV and extracardiac
TAPVC, preoperative PVO was considered to be a risk factor for
death1. Any significant PVO needs to be relieved at
the first palliative stage, which can be staged or concurrent
surgery11. In our study, all 6 patients with PVO were
addressed during BDG procedure. Four of them died, but there was no
direct correlation with PVO (Figure 1). No cases of postoperative
pulmonary vein stenosis were found. Univariate analysis, but not
multivariate analysis, indentified preoperative PVO as significant risk
factors for mortality (Table 2). Cumulative survival rate in patients
with preoperative PVO was lower than that in patients with no
preoperative PVO (p = 0.03, HR:0.535) (Figure 4).