The effect of the conduit size on middle-term outcomes in patients with extracardiac total cavopulmonary connection

Abstract

OBJECTIVES

The 18- and 16-mm conduits in extracardiac total cavopulmonary connection (eTCPC) were reported to be optimal based on energy loss and flow stagnation at the relatively early phase. However, because the artificial conduit lacks growth potential, we have recently encountered some cases in which the conduit needs to be changed several years after eTCPC. These cases prompted us to reconsider the surgical strategy for eTCPC.

METHODS

We reviewed our 20-year single-centre experience with eTCPC patients (n = 256) to compare the 18-mm conduit (n = 195) and 16-mm conduit (n = 61) in terms of mortality and morbidity.

RESULTS

The 16-mm conduit was used significantly more frequently in patients whose main chamber was right ventricle (P < 0.001). There was also a significant difference in preoperative inferior vena cava pressure (P = 0.008). There was a significant difference in the actuarial rate of freedom from late-occurring complications, including mortality, between the 2 groups (P = 0.003). There was a significant difference in the actuarial rate of reoperation-free survival (P = 0.042); however, there was no significant difference in resurgical intervention for the conduit (P = 0.333). In multivariate analysis, preoperative inferior vena cava pressure was an independent predictor for late-occurring complications (hazard ratio 1.19; P = 0.026). Conduit size (18 or 16 mm) itself was not an independent predictive factor for late-occurring complications (P = 0.690).

CONCLUSIONS

The mid-term clinical outcomes in patients who underwent eTCPC were excellent with low mortality. Preoperative inferior vena cava pressure was the only predictive risk factor for postoperative morbidity, and the 16 mm conduit was not predictive thereof.

Since the first description by Fontan and Baudet [1], several modifications and adaptations of the Fontan procedure have been introduced to improve surgical outcomes.

INTRODUCTION

Since the first description by Fontan and Baudet [1], several modifications and adaptations of the Fontan procedure have been introduced to improve surgical outcomes. Although these improvements have reduced perioperative mortality, attention has been directed towards long-term mortality and functional clinical status as well as the prevalence of late morbidities specific to Fontan physiology.

Currently, extracardiac conduit total cavopulmonary connection (eTCPC) is the most widely used procedure for Fontan modification worldwide [2, 3]. At our institution, eTCPC was introduced in 1996 and has been the procedure of choice for the Fontan operation since 2000 [4, 5]. In our institution, the target age and body weight for eTCPC are between 1 and 2 years old and 10 kg, respectively. Consequently, we used a graft with a diameter of 18 or 16 mm to fit the patients’ physical constitution. Recently, we have encountered some cases in which the conduit needed to be changed for a larger size several years after eTCPC. These cases prompted us to reconsider the surgical strategy for eTCPC including the appropriate size of the TCPC conduit.

We reviewed our 20-year single-centre experience with eTCPC patients to compare the 18 and 16 mm conduit in terms of mortality and morbidity. We also identified factors associated with morbidity in patients with eTCPC over a 20-year period.

PATIENTS AND METHODS

Ethical statement

This study was approved by the Institutional Ethics Review Board of Mt. Fuji Shizuoka Children’s Hospital (IRB approval; date 26 November 2019 number 60). The need for individual informed consent was waived due to the retrospective nature of the study.

A retrospective review of the medical records including in-hospital and outpatient notes, laboratory data, cardiac catheterization and other non-invasive images was performed for 256 patients who underwent eTCPC at our institution between January 2000 and December 2021. eTCPC using an 18-mm conduit was performed in 195 patients (Group 18) and eTCPC using a 16-mm conduit was performed in 61 patients (Group 16). Other types of Fontan operations such as intra- eTCPC, lateral tunnel Fontan, direct Fontan, one-lung Fontan, TCPC conversion and eTCPC using conduits other than 18 or 16 mm were excluded.

Surgical procedure

eTCPC was routinely performed via median sternotomy and standard cardiopulmonary bypass (CPB) with aortic and bicaval cannulation under mild-normal hypothermia as previously described [4, 5]. Cardiac arrest was performed only when intracardiac procedures were required. As an extracardiac conduit, we used an expanded polytetrafluoroethylene conduit (Gore-Tex vascular graft; W.K. Gore & Associates, Inc, Flagstaff, AZ, USA). The TCPC conduit selection was based on the physical attributes and cardiac structures. For example, when we judged that the 18-mm conduit may compress pulmonary veins, we tended to use the 16-mm conduit. When performing ‘intra-extra’ cardiac TCPC, we tended to use the 16-mm graft to prevent abnormal intracardiac turbulence. Preoperative computed tomography (CT) helped us to predict the size of the conduit. However, the final decision was made by surgeons intraoperatively.

Follow-up system and data collection

The patients were regularly followed up by paediatric cardiologists at Mt. Fuji Shizuoka Children’s Hospital and Shizuoka Prefectural General Hospital. Mortality, cause of death, morbidity and examination data were regularly tracked. The first postoperative cardiac catheterization was performed 6 months to 1 year after the Fontan procedure to assess haemodynamic variables. Repeated cardiac catheterization was generally considered at 6 years (before entering elementary school), 12 years (before entering junior high school) and 18 years (before graduating high school); however, the decision was made at the discretion of the cardiologist in charge. The primary endpoint was mortality and the secondary endpoints were morbidity (defined as requiring hospitalization) and haemodynamic variables obtained from postoperative cardiac catheterization.

Minimum cross-sectional area of eTCPC conduit from multidetector raw CT

Two radiation technologists measured the cross-sectional area of the eTCPC conduit using multi-detector raw CT (MDCT) with Zio Station Plus (Amin Co.Ltd, Tokyo, Japan). The latest MDCT which took more than 10 years after eTCPC was used for evaluation. The value of the ‘CT index’ was identified as a value that the measured cross-sectional area was divided by the original cross-sectional area of the conduit. The minimum ‘CT index’ values were compared between the 2 groups.

Statistical analysis

Data were expressed as means ± standard deviation for normally distributed continuous variables or median with interquartile range for skewed continuous variables. A probability value of <0.05 was considered statistically significant.

Differences in the demographic and clinical data were tested using the unpaired Student’s t-test, Mann–Whitney U test and Kruskal–Walls test for continuous variables, or Fisher’s exact test for categorical variables, as appropriate.

The estimated actuarial survival and freedom from late morbidity were calculated using the Kaplan–Meier method. The Cox proportional hazard regression model was used to determine the predictors of postoperative mortality and overall morbidity in univariate and multivariate analyses. Potential predictive variables were first determined using univariate analysis. Covariates with a probability value of <0.05 as determined by univariate analysis were included in multivariate analysis.

All statistical analyses were performed using JMP (version 16; SAS Institute, Inc, Cary, NC, USA).

RESULTS

Preoperative characteristics and preoperative/perioperative factors

Patient characteristics and preoperative variables from preoperative cardiac catheterizations are provided in Table 1. Preoperative cardiac catheterization was routinely performed. There was a significant difference in the main chamber between the 2 groups (P < 0.001). In particular, a 16-mm conduit was used more frequently in patients with right isomerism (P = 0.007). There was also a significant difference in inferior vena cava (IVC) pressure between the 2 groups (P = 0.008; 6.3 ± 1.6 mmHg Group 18 vs 7.1 ± 2.6 mmHg Group 16). There were no significant differences in other preoperative factors between the 2 groups.

Table 1:

Preoperative patient characteristics and preoperative/perioperative variables

	Group 18 (n = 195)	Group 16 (n = 61)	P-value
Preoperative patient characteristics
Female/male	87/108	31/30	0.397
Diagnosis
Right isomerism	27	18	0.007
HLHS	39	13	0.825
Single ventricle	40	11	0.667
PAIVS	26	2	0.014
Tricuspid atresia	20	3	0.177
Main chamber (RV/LV)	92/103	49/12	<0.001
Preoperative variables
SaO2 (%)	85.8 ± 3.5	84.9 ± 3.8	0.105
Cardiac index (l/min/m2)	3.67 ± 1.05	3.61 ± 0.87	0.656
SVCP (mmHg)	11.3 ± 1.7	11.8 ± 2.8	0.089
IVCP (mmHg)	6.3 ± 1.6	7.1 ± 2.6	0.008
mVEDP (mmHg)	7.5 ± 2.4	7.9 ± 3.2	0.263
Rp (U·m2)	1.6 ± 0.6	1.7 ± 0.8	0.600
PAI (mm2/m2)	221.3 ± 115.5	229.2 ± 129.2	0.711
Perioperative variables
Average age at eTCPC (years)	2.4 ± 1.3	1.9 ± 0.9	0.006
Median age at eTCPC (years)	2.0	1.7
Body weight at eTCPC (kg)	10.7 ± 2.0	9.2 ± 1.8	<0.001
Height at eTCPC (cm)	83.3 ± 8.6	77.6 ± 8.0	<0.001
Operation time (h)	6.7 ± 1.3	6.7 ± 1.4	0.779
CPB time (min)	140.9 ± 49.4	155.7 ± 50.7	0.044
The need for CA	67/195 (31.3%)	35/60 (51.7%)	0.002
CA time (min)	59.5 ± 27.3	62.8 ± 29.4	0.576
Fenestration (+)	14 (7.2%)	5 (8.2%)	0.794
Atrioventricular valve surgery (+) (including history)	47 (24.1%)	18 (29.5%)	0.403

CA: cardiac arrest; DORV: double outlet right ventricle; HLHS: hypoplastic left heart syndrome; IVCP: inferior vena cava pressure; LV: left ventricle; PAI: pulmonary artery index; PAIVS: pulmonary atresia with intact ventricular septum; Rp: pulmonary vascular resistance; RV: right ventricle; SaO₂: oxygen saturation; SVCP: superior vena cava pressure; TGA: transposition of the great arteries.

Perioperative variables are also provided in Table 1. There were significant differences in age, body weight and height at eTCPC between the 2 groups; the patients in Group 16 were younger and smaller than those in Group 18.

Fenestration was considered in patients with elevated pulmonary vascular resistance; however, the decision was made by the operator upon the termination of CPB. When needed, fenestration was ordinarily created using a 4-mm punch. Fenestration was created in 19/256 patients (7.4%) and there was no difference in the presence of fenestration between the 2 groups. The main concomitant procedures were performed in 100 patients including pulmonary artery (PA) plasty in 47, atrioventricular valve surgery in 32, atrial septal defect creation/enlargement in 19, ascending aorta plication in 12, release of pulmonary vein stenosis in 8, Damus–Kay–Stansel in 4 and aortic valve plasty in 3 (there was more than one concomitant procedures in a single patient). There was a significant difference in CPB duration between the 2 groups.

Postoperative mortality

The mean follow-up period was 9.3 years (range, 0.1–22.5 years). Early death occurred in one patient. A 19-month-old male with hypoplastic left heart syndrome who underwent eTCPC with fenestration died of Fontan failure from remaining severe postoperative pulmonary stenosis 1 month postoperatively. Late deaths occurred in 12 patients. The causes of death were Fontan failure including protein losing enteropathy and arrhythmia in 4, infection in 4, sudden death in 3 and cerebral infarction in one patient. The Kaplan–Meier estimated actuarial survival rate was 95.2%, 95.2% and 95.2% at 5, 10 and 15 years, respectively. The actuarial survival rate in Group 18 was 96.4%, 96.4% and 96.4% at 5, 10 and 15 years, respectively. The actuarial survival rate in Group 16 was 91.4%, 91.4 and 91.4% at 5, 10 and 15 years, respectively. There was no significant difference in actuarial survival between the 2 groups (P = 0.075).

Postoperative morbidity

Late-occurring complications

The main late-occurring complications were heart failure in 26 patients, resurgical intervention in 24, catheter intervention in 22, new onset arrhythmia in 18, protein-losing enteropathy in 10, prolonged pleural effusion in 9, thromboembolism in 8, liver cirrhosis in 4, plastic bronchitis in 3 and pulmonary arteriovenous fistula in 2 patients (there was more than one complication in a single patient).

The Kaplan–Meier estimated actuarial rate of freedom from late-occurring complications including mortality was 82.3% at 5 years, 75.0% at 10 years and 71.4% at 15 years. The actuarial rate of freedom from late-occurring complications in Group 18 was 87.5% at 5 years and 81.5% at 10 years. The actuarial rate of freedom from late-occurring complications in Group 16 was 70.3% at 5 years and 60.9% at 10 years. There was a significant difference in the actuarial rate of freedom from late-occurring complications, including mortality, between the 2 groups (P = 0.003) (Figs 1 and 2).

Figure 1:

Kaplan–Meier analysis for postoperative morbidity. Group 18 (blue line) and Group 16 (red line) are depicted separately. Kaplan–Meier estimates for morbidity with confidence limits are summarized in Table 2. Group 18 has a better morbidity rate compared to Group 16 (P = 0.003).

Figure 2:

Kaplan–Meier estimated actuarial rate for free from morbidity with confidence limits.

Analysis of predictive factors for late-occurring complications

The results of univariable and multivariable logistic regression analyses of late-occurring complications and each categorical variable are summarized in Table 2. In multivariable analysis, preoperative IVC pressure was an independent predictor for late-occurring complications (hazard ratio 1.19; 95% confidence interval 1.02–1.38; P = 0.026). The cut-off value of preoperative IVC pressure for late-occurring complications from the receiver operating characteristic curve was 8.0 mmHg (area under the curve, 0.68707). Conduit size (18 or 16 mm) was not an independent predictive factor for late-occurring complications (P = 0.690).

Table 2:

Statistical analysis for postoperative morbidity

	Univariable analysis			Multivariable analysis
	Hazard ratio	95% confidence interval	P-value	Hazard ratio	95% confidence interval	P-value
Gender
Female	1.00
Male	1.34	0.80–2.66	0.264
Body weight at eTCPC (kg)	0.99	0.87–1.13	0.980
Height at eTCPC (cm)	1.00	0.97–1.04	0.660
Age at eTCPC (years)	1.11	0.88–1.34	0.348
Main chamber
RV	1.81	1.94–3.12	0.030	1.88	0.96–3.67	0.060
LV	1.00			1.00
SaO2 (%)	0.96	0.90–1.03	0.212
Cardiac index (l/min/m2)	0.89	0.54–1.18	0.467
SVCP (mmHg)	1.31	1.15–1.48	<0.001	1.05	0.90–1.26	0.493
IVCP (mmHg)	1.33	1.18–1.47	<0.001	1.19	1.02–1.38	0.026
mVEDP (mmHg)	1.09	0.98–1.20	0.098
Rp (U·m2)	1.46	0.98–2.13	0.066
PAI (mm2/m2)	1.00	1.00–1.01	0.769
Operation time (h)	1.29	1.07–1.52	0.008	1.13	0.81–1.53	0.450
CPB time (min)	1.00	1.00–1.01	0.002	1.00	0.99–1.01	0.811
CA time (min)	1.00	0.99–1.01	0.375
Conduit size (mm)
18	1.00			1.00
16	2.19	1.30–3.71	0.004	1.15	0.58–2.30	0.690
Fenestration (+)	3.39	1.59–7.23	0.006	1.94	0.78–4.85	0.167
Atrioventricular valve surgery (+) (including history)	2.12	1.23–3.64	0.009	1.12	0.54–2.31	0.767

CA: cardiac arrest; IVCP: inferior vena cava pressure; LV: left ventricle; PAI: pulmonary artery index; Rp: pulmonary vascular resistance; RV: right ventricle; SaO₂: oxygen saturation; SVCP: superior vena cava pressure.

Late resurgical intervention

Thirty-one resurgical interventions other than operation-related pacemakers were performed in 26 patients, including conduit repair/exchange in 9, atrioventricular valve plasty in 8, atrioventicular valve replacement in 7, PA plasty in 3, creation of fenestration in 2, repair of pulmonary vein obstruction in 2, aortic valve plasty in 2 and aortic valve replacement in 2 (there was more than one procedure in a single patient). There was a significant difference in the actuarial rate of reoperation-free survival between the 2 groups (P = 0.042, log-rank test) (Figs 3 and 4). However, there was no significant difference between the free from resurgical intervention for the eTCPC conduit in the 2 groups (P = 0.333, log-rank test). In addition, a simple conduit exchange operation was performed on only 2 patients (one in Group 18 and one in Group 16).

Figure 3:

Kaplan–Meier analysis for reoperation-free survival. Group 18 (blue line) and Group 16 (red line) are depicted separately. Kaplan–Meier estimates actuarial rates for reoperation-free survival with confidence limits are summarized in Fig. 4. There was a significant difference in actuarial rate of reoperation-free survival between the 2 groups (P = 0.042).

Figure 4:

Kaplan–Meier estimated rate for reoperation-free survival with confidence limits.

Latest cardiac catheterization

Data regarding haemodynamic variables obtained from the latest postoperative cardiac catheterization were available for 217 patients (164 patients in Group 18 and 53 patients in Group 16) (Table 3). The levels of brain natriuretic peptide (P = 0.013) and main ventricular end-diastolic pressure (P = 0.008) were significant factors between the 2 groups. However, there were no significant differences in other factors, such as cardiac index, superior vena cava (SVC)/IVC pressure and arterial oxygen saturation between the 2 groups.

Table 3:

Variables from latest cardiac catheterization

	Group 18 (n = 164)	Group 16 (n = 53)	P-value
SaO2 (%)	94.3 ± 2.6	93.5 ± 3.2	0.087
BNP (pg/dl)	25.1 ± 31.8	39.1 ± 42.8	0.013
Cardiac index (l/min/m2)	3.36 ± 0.92	3.12 ± 1.02	0.108
SVCP (mmHg)	10.2 ± 2.5	10.5 ± 3.1	0.405
IVCP (mmHg)	10.1 ± 2.5	10.7 ± 3.2	0.112
mVEDP (mmHg)	6.1 ± 2.1	7.2 ± 3.5	0.008

BNP: brain natriuretic peptide; IVCP: inferior vena cava pressure; SaO₂: oxygen saturation; SVCP: superior vena cava pressure.

Minimum ‘CT index’

The average value of the minimum ‘CT index’, from the MDCT scan, which took more than 10 years after eTCPC, was 0.68 ± 0.10 in Group 16 (n = 24) and 0.84 ± 0.12 in Group 18 (n = 24). There was a significant difference between the 2 groups (P < 0.001). In addition, the number of cases in which the minimum ‘CT index’ value was below 0.75 (meaning ‘conduit one size down’) in Group 16 (17/24 cases) was significantly larger than that in Group 18 (8/24 cases) (P = 0.009).

DISCUSSION

We reviewed our 20-year single-centre experience with eTCPC patients using an 18-mm conduit and a 16-mm conduit in terms of mortality and morbidity. There were no significant differences with respect to mid-term mortality; however, there was a significant difference in morbidity. Preoperative IVC pressure was an independent predictive factor for morbidity in multivariable analysis; however, conduit size (18 or 16 mm) itself was not. Few reports have focused on conduit size, and to our knowledge, no reports have evaluated mid-term results after eTCPC.

At our institution, eTCPC has been the procedure of choice for the Fontan operation since 2000 because of its feasibility and advantages, such as surgical simplicity without aortic cross-clamp, small atrial wall stress, and optimal laminar flow with small energy loss. The 18- and 16-mm conduits in eTCPC were reported to be optimal based on energy loss and flow stagnation at the relatively early phase [6]. We performed this study to evaluate mortality and morbidity after eTCPC in the mid-term, focusing on the size of the eTCPC conduit.

There was no significant difference in mortality between the 2 groups; however, the morbidity in Group 16 was higher than that in Group 18. However, conduit size was not an independent predictive factor of morbidity in multivariable analysis. Moreover, there was a significant difference between the 2 groups in the main ventricle (right ventricle or left ventricle), age, and physical constitution at operation. In addition, the preoperative oxygen saturation level and cardiac index in Group 16 were lower than those in Group 18, with no significant difference. The preoperative SVC/IVC pressure, main ventricular end-diastolic pressure and pulmonary vascular resistance in Group 16 were higher than those in Group 18, with no significant difference, too. From these results, the main reason why we selected a 16-mm conduit was that some preoperative conditions, such as low oxygen saturation, which may increase arteriovenous collateral vessels leading to high pulmonary resistance, were deteriorating, and we could not wait for the operation. There were also other reasons why we used a 16-mm conduit. We selected a smaller conduit when a larger conduit may compress the pulmonary veins in the complex heart such as right isomerism. We speculate that the main cause of the frequent morbidity was the patient’s status, including haemodynamics and cardiac structures, and not the conduit size. Postoperative haemodynamics showed a similar trend.

There was no significant difference between the free from resurgical intervention in the 2 groups (P = 0.0538). Re-surgical intervention was mainly performed to improve deteriorated haemodynamics, such as atrioventricular valve insufficiency, aortic valve insufficiency and peripheral PA stenosis. Seven surgical interventions for the eTCPC conduit were additionally performed when other intracardiac surgical interventions, such as atrioventricular valve plasty, were performed; simple conduit exchange operations were performed on only 2 patients. Downing et al. [7] reported that two-thirds of Fontan survivors required surgical or catheter-based reintervention after 20 years. Reoperation after Fontan operation has been reported to have excellent mid-term results [8]. We may encounter more surgical interventions after eTCPC and will not hesitate to exchange or size up the eTCPC conduit.

The eTCPC conduit decreased in size as the patient grew older. In addition, the actual size of the eTCPC conduit decreased due to factors, such as the thrombus and changes of cardiac dimension. Amodeo et al. [9] found that the conduit internal diameter showed a 17.8 ± 7.6% reduction during the first 6 months after eTCPC using serial magnetic resonance imaging studies. Lee et al. [10] reported that the mean % decrease in the conduit cross-sectional area was 14.3 ± 8.5% by angiography during a mean follow-up of 36 months after surgery. To evaluate the actual size, we measured the cross-sectional area of the eTCPC conduit using MDCT which took more than 10 years after eTCPC. Although Lee et al. [10] also reported that the mean % decrease in the conduit cross-sectional area did not differ significantly according to conduit size, there was a significant difference in the minimum cross-sectional area (‘CT index’) between the 2 groups in this study. This may be because of the difference in the material, interval after surgery and number of cases.

Patel et al. [11] reported that the minimum Fontan conduit cross-sectional area correlated with the peak oxygen consumption. However, we did not include the minimum ‘CT index’ as a factor in the analysis for postoperative morbidity. This was because MDCT scans were not regularly planned, and some patients did not undergo MDCT evaluation because their conditions/haemodynamics were very stable.

In this study, preoperative IVC pressure was the only predictive risk factor for postoperative morbidity. Ordinarily, preoperative high PA pressure (equal to SVC pressure after bidirectional Glenn) and pulmonary resistance were listed as representative risk factors for post Fontan [12]; however, these were not included in this study. The main ventricular end-diastolic pressure, which may affect the IVC pressure, was also not a predictive factor. Thus, our results seem unique and require further investigation. We speculate that one reason for this was the presence of veno-venous collateral vessels (V-V collaterals). V-V collaterals develop before and after the Fontan procedure, which can lead to an increase in IVC pressure. V-V collaterals usually develop when a patient has a high level of SVC pressure and pulmonary resistance before the Fontan operation, which may lead to a decrease in SVC pressure. Thus, the high level of IVC pressure from the V-V collaterals may mask the high level of SVC pressure and pulmonary resistance. In our institution, large V-V collaterals were plugged before the Fontan procedure; however, these cases are rare. It was reported that embolization of V-V collaterals after Fontan procedure is associated with decreased survival [13]; however, the outcomes after aggressive embolization of V-V collaterals before Fontan procedure have not been reported. Further investigation of V-V collaterals is needed to verify this hypothesis.

The best timing for Fontan completion remains controversial. Older age at the time of surgery, such as >15 years of age, was reported to be a risk factor after the Fontan operation [14, 15]. Cao et al. [16] reported that undergoing the Fontan operation <3 years of age was not a risk factor for short- or long-term adverse outcomes. In our institution, the timing of Fontan completion was determined by the patients’ physical attributes, indicating whether an 18-mm conduit could be safely implanted. However, in some situations, such as low oxygen saturation which leads to the development of aortopulmonary collateral arteries and massive pulmonary arteriovenous fistulas, physicians cannot wait for the patient to grow enough for the 18-mm conduit to be used. The 16-mm conduit was not a predictive risk factors for mortality and morbidity after eTCPC in the mid-term and we will continue to follow-up patients according to our current strategy.

Limitations

This single-centre study had some limitations due to its retrospective, non-randomized nature. The power of this study was limited by the limited postoperative period and number of patients. The limited number of events may limit the reliability of Cox regression results in some cases. Future prospective multicentre studies are required to confirm our results.

CONCLUSIONS

The mid-term clinical outcomes in patients who underwent eTCPC with a 16-mm conduit or an 18-mm conduit were excellent with low mortality. Preoperative IVC pressure was the only predictive risk factor for postoperative morbidity, and the 16-mm conduit was not predictive thereof.

Glossary

ABBREVIATIONS

CPB

Cardiopulmonary bypass

CT

Computed tomography

eTCPC

Extracardiac conduit total cavopulmonary connection

IVC

Inferior vena cava

MDCT

Multi-detector raw computed tomography

PA

Pulmonary artery

SVC

Superior vena cava

FUNDING

This work was not supported by any other people or organizations that could inappropriately influence this work.

Conflict of interest: none declared.

DATA AVAILABILITY

The data underlying this article cannot be shared publicly due to the privacy of the study participants. Deanonymized data, after obtaining all pertinent regulatory approval, will be shared on reasonable request to the corresponding author.

Author contributions

Keiichi Hirose: Conceptualization; Data curation; Investigation; Writing—original draft. Akio Ikai: Conceptualization; Investigation. Hiroki Ito: Data curation; Writing—review & editing. Motonari Ishidou: Data curation; Investigation. Daisuke Toritsuka: Data curation; Investigation. Yuji Nakamura: Investigation; Visualization. Seito Watanabe: Validation; Visualization; Writing—review & editing. Eiji Nakatani: Formal analysis; Investigation. Kisaburo Sakamoto: Conceptualization; Project administration; Supervision.

Reviewer information

Interdisciplinary CardioVascular and Thoracic Surgery thanks Yoshihiro Oshima, Joachim O.M. Photiadis and the other, anonymous reviewers for their contribution to the peer review process of this article.