TY - JOUR
AU - Yaku,, Hitoshi
AB - Abstract Open in new tabDownload slide Open in new tabDownload slide OBJECTIVES The aim of this study was to clarify the impact of valved systemic ventricle–pulmonary artery (SV–PA) shunt on outcomes after stage-1 Norwood-type palliation (NP) compared with the modified Blalock–Taussig shunt. METHODS Consecutive patients who underwent NP between 2003 and 2019 were enrolled. SV–PA shunts using the expanded polytetrafluoroethylene valved conduit were implanted in 18 patients (valved SV–PA group), and another 18 patients underwent modified Blalock–Taussig shunt during NP (modified Blalock–Taussig shunt group). All valved conduits were made in our institution in advance. RESULTS No differences in baseline characteristics were found between the groups, except for shunt size. During a median 2.9 (interquartile range 0.4–6.4, maximum 14.2) years of follow-up, 8 (22.2%) patients died across both groups. There were no statistically significant differences in early mortality (5.5% vs 11.1%, P = 0.55) and overall survival rates at 5 years (80.8% vs 71.4%, P = 0.48) in the valved SV–PA and modified Blalock–Taussig shunt groups. No statistically significant difference was observed in the frequency of interventions between the groups (31% vs 33%, P = 1.0). At the time of the bidirectional Glenn procedure, the systemic ventricular end-diastolic volume index was significantly lower (84 ± 24 vs 106 ± 31 ml/m2, P = 0.05) and the ejection fraction was significantly greater (62 ± 8% vs 55 ± 9%, P = 0.03) in the valved SV–PA group. There was no statistically significant difference in the pulmonary artery index (228 ± 85 vs 226 ± 60 mm2/m2, P = 0.92). CONCLUSIONS A valved SV–PA shunt using an expanded polytetrafluoroethylene valved conduit was associated with preserved ventricular function after NP and did not impair pulmonary artery growth by controlling pulmonary regurgitation. Expanded polytetrafluoroethylene, Handmade expanded polytetrafluoroethylene valved conduit, Norwood procedure, Right ventricle–pulmonary artery shunt, Hypoplastic left heart syndrome INTRODUCTION Patients who undergo right ventricle–pulmonary artery (RV–PA) shunt concomitant with the Norwood procedure have better outcomes in terms of transplantation-free survival at 12 months [1] or 6 years [2] than those who undergo modified Blalock–Taussig (MBT) shunt; however, the RV–PA shunt involves more unintended interventions and complications. The advantages of RV–PA shunt in mortality and right ventricular function become less apparent with time after the bidirectional Glenn procedure (BDG) [3]. The reason could be that some of the negative factors related to the use of the RV–PA shunt, e.g. ventriculotomy and diastolic regurgitation through the conduit, become evident after BDG [4]. The conduit used as the RV–PA shunt is generally not equipped with a valve. Theoretically, diastolic conduit regurgitation can increase volume load and consequently compromise ventricular efficiency, which may be detrimental and predispose patients to progressive tricuspid regurgitation. Therefore, right ventricular function is expected to be preserved by adding the valve to the RV–PA shunt. Furthermore, increased volume and pulsatility of pulmonary blood flow may improve the growth of PAs. These factors are important for the patients with single ventricular physiology who require the Fontan procedure. There are a few recent reports of valved RV–PA shunt using some types of homograft valves, and their outcomes were not satisfactory in terms of homograft valve durability [5–8]. We have developed and reported the outcome of a small-diameter expanded polytetrafluoroethylene (ePTFE) conduit with bulging sinuses and valve [9–12]. This ePTFE valved conduit has been applied in Norwood-type palliation (NP) as a systemic ventricle-PA (SV–PA) shunt since 2003. Our purpose was to clarify the impact of valved SV–PA shunt on the outcomes after stage-1 NP compared with the MBT shunt. MATERIALS AND METHODS This study was approved by the Institutional Review Board of Kyoto Prefectural University of Medicine (ERB-C-1527). Study population From July 2003 to May 2019, we performed a retrospective analysis of consecutive patients with single-ventricle and systemic ventricular outflow tract obstruction who underwent stage-1 NP including 2-stage Norwood following bilateral PA banding at Kyoto Prefectural University of Medicine. Of these, 18 patients underwent NP with SV–PA shunt using the ePTFE valved conduit (valved SV–PA group) and the other 18 patients underwent NP with the MBT shunt using an ePTFE graft (MBT group). Five patients who underwent the Norwood procedure concomitant with BDG were excluded. Expanded polytetrafluoroethylene valved conduit with bulging sinuses All the conduits implanted in this study were made at the Kyoto Prefectural University of Medicine (Fig. 1). The conduits are handmade ePTFE valved conduits with bulging sinuses, imitating the sinus of Valsalva, and a fan-shaped ePTFE valve sutured on the inside of the graft [13]. The bulging sinuses were moulded on ePTFE grafts (non-ringed stretch Vascular Graft; W.L. Gore & Associates Inc., Flagstaff, AZ, USA) by heat and pressure using a custom-made machine. The fan-shaped valves were cut from the 0.1-mm ePTFE membrane (Preclude Pericardial Membrane; W.L. Gore & Associates Inc.) and sutured on the lumen side of the graft turned inside out. All the processes were completed by surgeons on the sterile field in the operating room, and then, all the finished valved conduits were sterilized [9–11]. The size of the conduit, ranging from 5 to 8 mm in diameter, was selected depending on the physical constitution and the anatomical features of the heart [11]. The conduits with a diameter of 5 and 6 mm had a monocuspid valve, and one of the 8-mm conduits had a bicuspid valve. Figure 1: Open in new tabDownload slide The expanded polytetrafluoroethylene valved conduits with bulging sinuses. View of the valve of the 8-mm diameter conduit from above in the opening (A-1) and closing (A-2) positions, and from outside the grafts with a diameter of 8 mm (B) and 6 mm (C). Figure 1: Open in new tabDownload slide The expanded polytetrafluoroethylene valved conduits with bulging sinuses. View of the valve of the 8-mm diameter conduit from above in the opening (A-1) and closing (A-2) positions, and from outside the grafts with a diameter of 8 mm (B) and 6 mm (C). Operative technique Cardiopulmonary bypass was instituted through double arterial cannulations, an ePTFE graft anastomosed to the right brachiocephalic artery and the descending aorta directly above the diaphragm, and bicaval venous cannulations. After the ductal tissue was resected completely and bilateral PAs were excised en bloc, the pulmonary trunk was sutured to roll up into a chimney [14, 15]. The tapered chimney-like pulmonary trunk gained adequate length and was anastomosed directly to the aortic arch and descending aorta without a patch. The PA bifurcation was patched with autologous pericardium to form the central PA, and pulmonary blood supply was re-established with the MBT shunt using an ePTFE graft from the innominate artery to the right PA or the SV–PA shunt using the ePTFE valved conduit from the ventricle to the central PA at the bifurcation. In cases of valved SV–PA shunt, the proximal end of the conduit was anastomosed directly to the systemic ventricular free wall. Eleven patients underwent shunt banding during NP or delayed sternal closure because they had implantation of a slightly larger graft than the optimal size to manage postoperative severe hypoxia due to pulmonary hypertension after weaning from cardiopulmonary bypass. Therefore, the patients who underwent 2-stage adjustment of the pulmonary blood flow during delayed sternal closure were not included in the unintended intervention cases. The lumen of the ePTFE graft was narrowly tucked with Titanium Hemostatic Clips (Vitalitec International, Inc., Domalain, France). Data collection and statistical analysis Preoperative and postoperative data were collected retrospectively from the patients’ medical records. All patients were evaluated with cardiac catheterization and 2-dimensional and Doppler echocardiography before BDG. Ventricular dysfunction was defined as the fractional area change of <35% in the right ventricle-dependent patients or the ejection fraction (EF) of <50% in the left ventricle-dependent patients. The pulmonary artery index (the Nakata index, which is the combined right PA and left PA cross-sectional area indexed to the body surface area) was used to estimate PA development [16]. Statistical analyses were performed using IBM SPSS Statistics for Mac v.24 (IBM Corp. Armonk, NY, USA). All continuous variables are presented as mean ± standard deviation or median [interquartile range (IQR)]. Two-sample t-test and Mann–Whitney U-test were used for parametric and non-parametric comparisons of continuous variables, respectively. Categorical data were compared using the χ2 or Fisher’s exact test; the latter was used when the expected value in any category was <5. Kaplan–Meier survival analysis and the log-rank test were used to compare survival between the groups. RESULTS Patients The median age at NP was 59.5 (IQR 38.3–95) days in the valved SV–PA group and 59 (IQR 41.3–89.8) days in the MBT group. There were no statistically significant differences in demographic data or preoperative risk factors at the time of NP between the groups, except for shunt size (Table 1). No difference in dominant ventricular morphology was either observed between the groups. Table 1: Baseline characteristics Baseline variables,aN (%) or mean ± SD . Valved SV–PA (n = 18) . MBT (n = 18) . P-value . Male 11 (64.7) 9 (50) 0.50b Age (days) 65 ± 44 64 ± 36 0.94 Body weight (kg) 3.7 ± 1.0 3.8 ± 0.8 0.97 BSA (m2) 0.22 ± 0.04 0.22 ± 0.03 0.86 Bilateral PAB 10 (55.6) 15 (83.3) 0.14c AVVR ≥ moderate 5 (27.8) 8 (44.4) 0.30b Ventricular dysfunction 3 (16.7) 1 (5.6) 0.60c Shunt size (mm) 5.8 ± 1.2 3.7 ± 0.5 <0.01  Median (range) 5 (5–8) 3.5 (3–5) Diagnosis  RV dependent 14 (77.8) 14 (77.8) 1.0   Classical HLHS 9 6   CoA/IAA with LVOTO 3 2   Critical AS 1 2   DORV, MA and CoA 0 2   Single RV, AS and CoA 0 2   Unbalanced AVSD and AS 1 0  LV dependent 4 (22.2) 4 (22.2)   Single LV, SAS and CoA 2 0   DORV, hypoRV and CoA 1 2   TA with TGA and CoA 1 1   l-TGA and CoA 0 1 Baseline variables,aN (%) or mean ± SD . Valved SV–PA (n = 18) . MBT (n = 18) . P-value . Male 11 (64.7) 9 (50) 0.50b Age (days) 65 ± 44 64 ± 36 0.94 Body weight (kg) 3.7 ± 1.0 3.8 ± 0.8 0.97 BSA (m2) 0.22 ± 0.04 0.22 ± 0.03 0.86 Bilateral PAB 10 (55.6) 15 (83.3) 0.14c AVVR ≥ moderate 5 (27.8) 8 (44.4) 0.30b Ventricular dysfunction 3 (16.7) 1 (5.6) 0.60c Shunt size (mm) 5.8 ± 1.2 3.7 ± 0.5 <0.01  Median (range) 5 (5–8) 3.5 (3–5) Diagnosis  RV dependent 14 (77.8) 14 (77.8) 1.0   Classical HLHS 9 6   CoA/IAA with LVOTO 3 2   Critical AS 1 2   DORV, MA and CoA 0 2   Single RV, AS and CoA 0 2   Unbalanced AVSD and AS 1 0  LV dependent 4 (22.2) 4 (22.2)   Single LV, SAS and CoA 2 0   DORV, hypoRV and CoA 1 2   TA with TGA and CoA 1 1   l-TGA and CoA 0 1 a If there are no superscript letters, data were tested by 2-sample t-test. b P-value based on χ2 test. c P-value based on Fisher’s exact test. AS: aortic stenosis; AVSD: atrioventricular septal defect; AVVR: atrioventricular valve regurgitation; BSA: body surface area; CoA: coarctation of the aorta; DORV: double outlet right ventricle; HLHS: hypoplastic left heart syndrome; IAA: interrupted aortic arch; LV: left ventricle; LVOTO: left ventricular outflow tract obstruction; MA: mitral atresia; MBT: modified Blalock–Taussig shunt; PAB: pulmonary artery banding; RV: right ventricle; SAS: subaortic stenosis; SD: standard deviation; SV–PA: systemic ventricle–pulmonary artery; TA: tricuspid atresia; TGA: transposition of the great arteries. Open in new tab Table 1: Baseline characteristics Baseline variables,aN (%) or mean ± SD . Valved SV–PA (n = 18) . MBT (n = 18) . P-value . Male 11 (64.7) 9 (50) 0.50b Age (days) 65 ± 44 64 ± 36 0.94 Body weight (kg) 3.7 ± 1.0 3.8 ± 0.8 0.97 BSA (m2) 0.22 ± 0.04 0.22 ± 0.03 0.86 Bilateral PAB 10 (55.6) 15 (83.3) 0.14c AVVR ≥ moderate 5 (27.8) 8 (44.4) 0.30b Ventricular dysfunction 3 (16.7) 1 (5.6) 0.60c Shunt size (mm) 5.8 ± 1.2 3.7 ± 0.5 <0.01  Median (range) 5 (5–8) 3.5 (3–5) Diagnosis  RV dependent 14 (77.8) 14 (77.8) 1.0   Classical HLHS 9 6   CoA/IAA with LVOTO 3 2   Critical AS 1 2   DORV, MA and CoA 0 2   Single RV, AS and CoA 0 2   Unbalanced AVSD and AS 1 0  LV dependent 4 (22.2) 4 (22.2)   Single LV, SAS and CoA 2 0   DORV, hypoRV and CoA 1 2   TA with TGA and CoA 1 1   l-TGA and CoA 0 1 Baseline variables,aN (%) or mean ± SD . Valved SV–PA (n = 18) . MBT (n = 18) . P-value . Male 11 (64.7) 9 (50) 0.50b Age (days) 65 ± 44 64 ± 36 0.94 Body weight (kg) 3.7 ± 1.0 3.8 ± 0.8 0.97 BSA (m2) 0.22 ± 0.04 0.22 ± 0.03 0.86 Bilateral PAB 10 (55.6) 15 (83.3) 0.14c AVVR ≥ moderate 5 (27.8) 8 (44.4) 0.30b Ventricular dysfunction 3 (16.7) 1 (5.6) 0.60c Shunt size (mm) 5.8 ± 1.2 3.7 ± 0.5 <0.01  Median (range) 5 (5–8) 3.5 (3–5) Diagnosis  RV dependent 14 (77.8) 14 (77.8) 1.0   Classical HLHS 9 6   CoA/IAA with LVOTO 3 2   Critical AS 1 2   DORV, MA and CoA 0 2   Single RV, AS and CoA 0 2   Unbalanced AVSD and AS 1 0  LV dependent 4 (22.2) 4 (22.2)   Single LV, SAS and CoA 2 0   DORV, hypoRV and CoA 1 2   TA with TGA and CoA 1 1   l-TGA and CoA 0 1 a If there are no superscript letters, data were tested by 2-sample t-test. b P-value based on χ2 test. c P-value based on Fisher’s exact test. AS: aortic stenosis; AVSD: atrioventricular septal defect; AVVR: atrioventricular valve regurgitation; BSA: body surface area; CoA: coarctation of the aorta; DORV: double outlet right ventricle; HLHS: hypoplastic left heart syndrome; IAA: interrupted aortic arch; LV: left ventricle; LVOTO: left ventricular outflow tract obstruction; MA: mitral atresia; MBT: modified Blalock–Taussig shunt; PAB: pulmonary artery banding; RV: right ventricle; SAS: subaortic stenosis; SD: standard deviation; SV–PA: systemic ventricle–pulmonary artery; TA: tricuspid atresia; TGA: transposition of the great arteries. Open in new tab Postoperative course and clinical data after Norwood-type palliation The period until delayed sternal closure and extubation was significantly longer in the valved SV–PA group than in the MBT group (P = 0.02 and 0.02). In contrast, no significant difference was found in the length of stay in the intensive care unit. The length of hospital stay was significantly longer in the MBT group than in the valved SV–PA group (P < 0.01). The mean postoperative peripheral oxygen saturation in the general ward was 3% higher in the valved SV–PA than in the MBT group, but the difference did not reach statistical significance (78% ± 4% vs 75% ± 9%, P = 0.15). No significant difference was also observed in brain natriuretic peptide (P = 0.48). The prevalence of moderate-to-severe atrioventricular valve regurgitation examined prior to discharge was similar in both groups (Table 2). Table 2: Perioperative and postoperative clinical data Postoperative data,aN (%) or median (IQR) . Valved SV–PA (n = 18) . MBT (n = 18) . P-value . Open sternum 18 (100) 14 (77.8) 0.10b Delayed sternal closure (days) 7 (4–7) 3 (2–5) 0.02 Nitrogen oxide (days) 2.5 (1–3) 1 (1–2) 0.18 Extubation (days) 11.5 (8–14) 6 (6–9) 0.02 PICU stay (days) 21 (14–29) 22 (13–37) 0.91 Hospital stay (days) 68 (58–119) 159 (81–289) <0.01 SpO2 (%), mean ± SD 78 ± 4 75 ± 9 0.15c BNP (pg/ml) 183 (95–303) 145 (96–210) 0.48 AVVR ≥ moderate 6 (38) 8 (50) 0.48d ECMO 1 (6) 3 (17) 0.60b Resuscitation 2 (11) 3 (17) 1.0b Reintubation 4 (22) 6 (33) 0.71b Early deathe 1 (6) 2 (11) 1.0b Postoperative data,aN (%) or median (IQR) . Valved SV–PA (n = 18) . MBT (n = 18) . P-value . Open sternum 18 (100) 14 (77.8) 0.10b Delayed sternal closure (days) 7 (4–7) 3 (2–5) 0.02 Nitrogen oxide (days) 2.5 (1–3) 1 (1–2) 0.18 Extubation (days) 11.5 (8–14) 6 (6–9) 0.02 PICU stay (days) 21 (14–29) 22 (13–37) 0.91 Hospital stay (days) 68 (58–119) 159 (81–289) <0.01 SpO2 (%), mean ± SD 78 ± 4 75 ± 9 0.15c BNP (pg/ml) 183 (95–303) 145 (96–210) 0.48 AVVR ≥ moderate 6 (38) 8 (50) 0.48d ECMO 1 (6) 3 (17) 0.60b Resuscitation 2 (11) 3 (17) 1.0b Reintubation 4 (22) 6 (33) 0.71b Early deathe 1 (6) 2 (11) 1.0b a Data on the number of days and BNP: Mann–Whitney U-test. b P-value based on Fisher’s exact test. c P-value based on 2-sample t-test. d P-value based on χ2 test. e Defined as death within 30 days. AVVR: atrioventricular valve regurgitation; BNP: brain natriuretic peptide; ECMO: extracorporeal membrane oxygenation; IQR: interquartile range; MBT: modified Blalock–Taussig shunt; PICU: paediatric intensive care unit; SpO2: peripheral oxygen saturation; SV–PA: systemic ventricle–pulmonary artery. Open in new tab Table 2: Perioperative and postoperative clinical data Postoperative data,aN (%) or median (IQR) . Valved SV–PA (n = 18) . MBT (n = 18) . P-value . Open sternum 18 (100) 14 (77.8) 0.10b Delayed sternal closure (days) 7 (4–7) 3 (2–5) 0.02 Nitrogen oxide (days) 2.5 (1–3) 1 (1–2) 0.18 Extubation (days) 11.5 (8–14) 6 (6–9) 0.02 PICU stay (days) 21 (14–29) 22 (13–37) 0.91 Hospital stay (days) 68 (58–119) 159 (81–289) <0.01 SpO2 (%), mean ± SD 78 ± 4 75 ± 9 0.15c BNP (pg/ml) 183 (95–303) 145 (96–210) 0.48 AVVR ≥ moderate 6 (38) 8 (50) 0.48d ECMO 1 (6) 3 (17) 0.60b Resuscitation 2 (11) 3 (17) 1.0b Reintubation 4 (22) 6 (33) 0.71b Early deathe 1 (6) 2 (11) 1.0b Postoperative data,aN (%) or median (IQR) . Valved SV–PA (n = 18) . MBT (n = 18) . P-value . Open sternum 18 (100) 14 (77.8) 0.10b Delayed sternal closure (days) 7 (4–7) 3 (2–5) 0.02 Nitrogen oxide (days) 2.5 (1–3) 1 (1–2) 0.18 Extubation (days) 11.5 (8–14) 6 (6–9) 0.02 PICU stay (days) 21 (14–29) 22 (13–37) 0.91 Hospital stay (days) 68 (58–119) 159 (81–289) <0.01 SpO2 (%), mean ± SD 78 ± 4 75 ± 9 0.15c BNP (pg/ml) 183 (95–303) 145 (96–210) 0.48 AVVR ≥ moderate 6 (38) 8 (50) 0.48d ECMO 1 (6) 3 (17) 0.60b Resuscitation 2 (11) 3 (17) 1.0b Reintubation 4 (22) 6 (33) 0.71b Early deathe 1 (6) 2 (11) 1.0b a Data on the number of days and BNP: Mann–Whitney U-test. b P-value based on Fisher’s exact test. c P-value based on 2-sample t-test. d P-value based on χ2 test. e Defined as death within 30 days. AVVR: atrioventricular valve regurgitation; BNP: brain natriuretic peptide; ECMO: extracorporeal membrane oxygenation; IQR: interquartile range; MBT: modified Blalock–Taussig shunt; PICU: paediatric intensive care unit; SpO2: peripheral oxygen saturation; SV–PA: systemic ventricle–pulmonary artery. Open in new tab Mortality and events Early mortality after NP (within 30 days) was 8.3% and did not differ between the valved SV–PA (n = 1, 5.5%) and MBT (n = 2, 11.1%) groups (P = 1.0). Cardiopulmonary resuscitation after NP was performed in 2 valved SV–PA and 3 MBT patients. One patient in the valved SV–PA and 3 patients in the MBT group required extracorporeal membrane oxygenation due to failure to wean from cardiopulmonary bypass or during cardiopulmonary resuscitation in the intensive care unit. During a median 2.9 (IQR 0.4–6.4, maximum 14.2) years of follow-up, 8 (22.2%) patients died across both groups. Three patients (16.7%) in the valved SV–PA group died: 1 of acute heart failure 3 days after NP, 1 of multi-organ failure 2 months after NP and 1 of sudden death during catheterization before BDG. Five patients (27.8%) died in the MBT group: 1 of acute heart failure 2 days after NP, 1 of airway haemorrhage 8 days after NP, 1 of sudden death while crying 51 days after NP, 1 of Glenn failure 5 months after NP and 1 of pneumonia 9 months after NP. Overall survival rates at 5 years were 80.8% and 71.4% in the valved SV–PA and MBT groups, respectively, with the difference being non-significant (P = 0.48, log-rank test; Fig. 2). Figure 2: Open in new tabDownload slide Kaplan–Meier estimate of overall survival comparing the valved SV–PA and MBT groups. Overall survival rates at 5 years were 80.8% and 71.4% in the valved SV–PA (blue) and MBT (red) groups, respectively, with the difference being non-significant (P = 0.48, log-rank test). Light-coloured bands represent 95% confidence intervals. MBT: modified Blalock–Taussig shunt; SV–PA: systemic ventricle–pulmonary artery. Figure 2: Open in new tabDownload slide Kaplan–Meier estimate of overall survival comparing the valved SV–PA and MBT groups. Overall survival rates at 5 years were 80.8% and 71.4% in the valved SV–PA (blue) and MBT (red) groups, respectively, with the difference being non-significant (P = 0.48, log-rank test). Light-coloured bands represent 95% confidence intervals. MBT: modified Blalock–Taussig shunt; SV–PA: systemic ventricle–pulmonary artery. Inter-stage interventions Percutaneous or surgical interventions in the valved SV–PA conduit or BT shunt were performed in 9 cases. Unintended interventions within 30 days of NP were found only in the MBT group, but the difference did not reach statistical significance (0% valved SV–PA vs 13% MBT, P = 0.48). No statistically significant difference was observed in the frequency of both types of interventions between the valved SV–PA and MBT groups (31% vs 33%, P = 1.0). Interventions to increase pulmonary blood flow were performed in 4 valved SV–PA and 4 MBT patients, and 1 intervention to reduce pulmonary blood flow was performed in 1 MBT patient. There was also no statistically significant difference in the types of interventions between the groups (P = 0.52; Table 3 and Fig. 3). Figure 3: Open in new tabDownload slide Three-dimensional computed tomography and angiograms of the SV–PA shunt. Three-dimensional computed tomography prior to discharge after Norwood-type palliation showed that the valved SV–PA shunt was anastomosed proximally to the right ventricle (A-1) and distally to the central pulmonary artery (A-2). Angiograms performed at the pre-Glenn cardiac catheterization showed that the valved SV–PA shunt had no evidence of stenosis at the segment of valve and was narrowed by clips and the valve was moving well (B-1). The light blue shaded area represents the shape of the SV–PA shunt, the blue lines represent the valve and the yellow bars represent the clips regulating blood flow (B-2). SV–PA: systemic ventricle–pulmonary artery. Figure 3: Open in new tabDownload slide Three-dimensional computed tomography and angiograms of the SV–PA shunt. Three-dimensional computed tomography prior to discharge after Norwood-type palliation showed that the valved SV–PA shunt was anastomosed proximally to the right ventricle (A-1) and distally to the central pulmonary artery (A-2). Angiograms performed at the pre-Glenn cardiac catheterization showed that the valved SV–PA shunt had no evidence of stenosis at the segment of valve and was narrowed by clips and the valve was moving well (B-1). The light blue shaded area represents the shape of the SV–PA shunt, the blue lines represent the valve and the yellow bars represent the clips regulating blood flow (B-2). SV–PA: systemic ventricle–pulmonary artery. Table 3: Interventions for conduits or shunts during the inter-stage period Variables, N (%) . Valved SV–PA (n = 13) . MBT (n = 15) . P-value . Within 30 days of NP 0 (0) 2 (13) 0.48a Types of interventions 0.52b  Percutaneous   Conduit or shunt balloon angioplasty 2 2  Surgical   Replacement with larger conduit or shunt 1 2   MBT addition 1 0   Regulation of pulmonary blood flow 0 1 Total 4 (31) 5 (33) 1.0a Variables, N (%) . Valved SV–PA (n = 13) . MBT (n = 15) . P-value . Within 30 days of NP 0 (0) 2 (13) 0.48a Types of interventions 0.52b  Percutaneous   Conduit or shunt balloon angioplasty 2 2  Surgical   Replacement with larger conduit or shunt 1 2   MBT addition 1 0   Regulation of pulmonary blood flow 0 1 Total 4 (31) 5 (33) 1.0a a P-value based on Fisher’s exact test. b χ2 test among the types of interventions. NP: stage-1 Norwood-type palliation; MBT: modified Blalock–Taussig shunt; SV–PA: systemic ventricle–pulmonary artery. Open in new tab Table 3: Interventions for conduits or shunts during the inter-stage period Variables, N (%) . Valved SV–PA (n = 13) . MBT (n = 15) . P-value . Within 30 days of NP 0 (0) 2 (13) 0.48a Types of interventions 0.52b  Percutaneous   Conduit or shunt balloon angioplasty 2 2  Surgical   Replacement with larger conduit or shunt 1 2   MBT addition 1 0   Regulation of pulmonary blood flow 0 1 Total 4 (31) 5 (33) 1.0a Variables, N (%) . Valved SV–PA (n = 13) . MBT (n = 15) . P-value . Within 30 days of NP 0 (0) 2 (13) 0.48a Types of interventions 0.52b  Percutaneous   Conduit or shunt balloon angioplasty 2 2  Surgical   Replacement with larger conduit or shunt 1 2   MBT addition 1 0   Regulation of pulmonary blood flow 0 1 Total 4 (31) 5 (33) 1.0a a P-value based on Fisher’s exact test. b χ2 test among the types of interventions. NP: stage-1 Norwood-type palliation; MBT: modified Blalock–Taussig shunt; SV–PA: systemic ventricle–pulmonary artery. Open in new tab Pre-bidirectional Glenn procedure characteristics At the time of pre-BDG evaluation, no statistically significant differences were found in diastolic blood pressure, pulse pressure and systemic ventricular end-diastolic pressure between the groups. The systemic ventricular end-diastolic volume index was lower in the valved SV–PA than in the MBT group (84 ± 24 vs 106 ± 31 ml/m2, P = 0.047). The EF measured by ventriculography was greater in the valved SV–PA group (62 ± 8% vs 55 ± 9%, P = 0.03). The pulmonary-to-systemic flow ratio (Qp/Qs) was significantly lower in the valved SV–PA group (0.69 ± 0.3 vs 1.06 ± 0.52, P = 0.04). The mean arterial oxygen saturation was 71 ± 6% in the valved SV–PA group and 75 ± 6 in the MBT group, although the difference did not reach statistical significance (P = 0.09). By contrast, statistically significant differences were not observed in parameters related to PA growth, such as the PA index, mean PA pressure and pulmonary vascular resistance. No statistically significant difference was also observed in brain natriuretic peptide (P = 0.24; Table 4). Table 4: Pre-BDG cardiac catheterization data and BNP Pre-BDG data, mean ± SD or median (IQR) . Valved SV–PA (n = 13) . MBT (n = 15) . P-valuea . Diastolic BP (mmHg) 46 ± 8 43 ± 7 0.19 Pulse pressure (mmHg) 45 ± 9 46 ± 7 0.59 EDP (mmHg) 9 ± 4 9 ± 3 0.42 EDVI (ml/m2) 84 ± 24 106 ± 31 0.05 EF (%) 62 ± 8 55 ± 9 0.03 SaO2 (%) 71 ± 6 75 ± 6 0.09 PA index (mm2/m2) 228 ± 85 226 ± 60 0.92 mPAP (mmHg) 17 ± 4 15 ± 3 0.30 Rp (wood) 2.48 ± 1.36 1.91 ± 1.0 0.22 Qp/Qs 0.69 ± 0.3 1.06 ± 0.52 0.04 BNP (pg/ml) 54 (30–90) 88 (32–570) 0.24b Pre-BDG data, mean ± SD or median (IQR) . Valved SV–PA (n = 13) . MBT (n = 15) . P-valuea . Diastolic BP (mmHg) 46 ± 8 43 ± 7 0.19 Pulse pressure (mmHg) 45 ± 9 46 ± 7 0.59 EDP (mmHg) 9 ± 4 9 ± 3 0.42 EDVI (ml/m2) 84 ± 24 106 ± 31 0.05 EF (%) 62 ± 8 55 ± 9 0.03 SaO2 (%) 71 ± 6 75 ± 6 0.09 PA index (mm2/m2) 228 ± 85 226 ± 60 0.92 mPAP (mmHg) 17 ± 4 15 ± 3 0.30 Rp (wood) 2.48 ± 1.36 1.91 ± 1.0 0.22 Qp/Qs 0.69 ± 0.3 1.06 ± 0.52 0.04 BNP (pg/ml) 54 (30–90) 88 (32–570) 0.24b a P-value based on 2-sample t-test. b Mann–Whitney U-test. BDG: bidirectional Glenn procedure; BNP: brain natriuretic peptide; BP: blood pressure; EDP: systemic ventricular end-diastolic pressure; EDVI: systemic ventricular end-diastolic volume index; EF: ejection fraction; IQR: interquartile range; MBT: modified Blalock–Taussig shunt; mPAP: main pulmonary artery pressure; PA index: pulmonary artery index; Qp/Qs: the pulmonary-to-systemic flow ratio; Rp: pulmonary vascular resistance; SaO2: arterial oxygen saturation; SD: standard deviation; SV–PA: systemic ventricle–pulmonary artery. Open in new tab Table 4: Pre-BDG cardiac catheterization data and BNP Pre-BDG data, mean ± SD or median (IQR) . Valved SV–PA (n = 13) . MBT (n = 15) . P-valuea . Diastolic BP (mmHg) 46 ± 8 43 ± 7 0.19 Pulse pressure (mmHg) 45 ± 9 46 ± 7 0.59 EDP (mmHg) 9 ± 4 9 ± 3 0.42 EDVI (ml/m2) 84 ± 24 106 ± 31 0.05 EF (%) 62 ± 8 55 ± 9 0.03 SaO2 (%) 71 ± 6 75 ± 6 0.09 PA index (mm2/m2) 228 ± 85 226 ± 60 0.92 mPAP (mmHg) 17 ± 4 15 ± 3 0.30 Rp (wood) 2.48 ± 1.36 1.91 ± 1.0 0.22 Qp/Qs 0.69 ± 0.3 1.06 ± 0.52 0.04 BNP (pg/ml) 54 (30–90) 88 (32–570) 0.24b Pre-BDG data, mean ± SD or median (IQR) . Valved SV–PA (n = 13) . MBT (n = 15) . P-valuea . Diastolic BP (mmHg) 46 ± 8 43 ± 7 0.19 Pulse pressure (mmHg) 45 ± 9 46 ± 7 0.59 EDP (mmHg) 9 ± 4 9 ± 3 0.42 EDVI (ml/m2) 84 ± 24 106 ± 31 0.05 EF (%) 62 ± 8 55 ± 9 0.03 SaO2 (%) 71 ± 6 75 ± 6 0.09 PA index (mm2/m2) 228 ± 85 226 ± 60 0.92 mPAP (mmHg) 17 ± 4 15 ± 3 0.30 Rp (wood) 2.48 ± 1.36 1.91 ± 1.0 0.22 Qp/Qs 0.69 ± 0.3 1.06 ± 0.52 0.04 BNP (pg/ml) 54 (30–90) 88 (32–570) 0.24b a P-value based on 2-sample t-test. b Mann–Whitney U-test. BDG: bidirectional Glenn procedure; BNP: brain natriuretic peptide; BP: blood pressure; EDP: systemic ventricular end-diastolic pressure; EDVI: systemic ventricular end-diastolic volume index; EF: ejection fraction; IQR: interquartile range; MBT: modified Blalock–Taussig shunt; mPAP: main pulmonary artery pressure; PA index: pulmonary artery index; Qp/Qs: the pulmonary-to-systemic flow ratio; Rp: pulmonary vascular resistance; SaO2: arterial oxygen saturation; SD: standard deviation; SV–PA: systemic ventricle–pulmonary artery. Open in new tab Clinical course Two patients in the valved SV–PA group and 1 in the MBT group died during the inter-stage period. Eleven valved SV–PA and 14 MBT patients completed BDG. Patients in the valved SV–PA group underwent BDG at a median age of 286 days (294 ± 67, n = 11) and in the MBT group at 305 days (301 ± 92, n = 14; P = 0.84). No statistically significant difference was observed in the rate of BDG completion between the groups (P = 0.28). Two patients in the MBT group died before the TCPC: 1 of pneumonia and another of Glenn failure. Seven valved SV–PA and 9 MBT patients completed TCPC. No statistically significant difference was also observed in the TCPC-completion rate between the groups (P = 0.48; Table 5). Table 5: Clinical course after NP Status, N (%) . Valved SV–PA . MBT . P-valuea . Inter-stage death 2 1  Unsuitable for BDG 2 1 Waiting for BDG 2 0 BDG completion 11 (61) 14 (78) 0.28  Died before TCPC 0 2  Unsuitable for TCPC 0 1  Waiting for TCPC 4 2 TCPC completion 7 (39) 9 (50) 0.50 Status, N (%) . Valved SV–PA . MBT . P-valuea . Inter-stage death 2 1  Unsuitable for BDG 2 1 Waiting for BDG 2 0 BDG completion 11 (61) 14 (78) 0.28  Died before TCPC 0 2  Unsuitable for TCPC 0 1  Waiting for TCPC 4 2 TCPC completion 7 (39) 9 (50) 0.50 a P-value based on χ2 test. BDG: bidirectional Glenn procedure; MBT: modified Blalock–Taussig shunt; NP: Norwood-type palliation; SV–PA: systemic ventricle–pulmonary artery; TCPC: total cavopulmonary connection. Open in new tab Table 5: Clinical course after NP Status, N (%) . Valved SV–PA . MBT . P-valuea . Inter-stage death 2 1  Unsuitable for BDG 2 1 Waiting for BDG 2 0 BDG completion 11 (61) 14 (78) 0.28  Died before TCPC 0 2  Unsuitable for TCPC 0 1  Waiting for TCPC 4 2 TCPC completion 7 (39) 9 (50) 0.50 Status, N (%) . Valved SV–PA . MBT . P-valuea . Inter-stage death 2 1  Unsuitable for BDG 2 1 Waiting for BDG 2 0 BDG completion 11 (61) 14 (78) 0.28  Died before TCPC 0 2  Unsuitable for TCPC 0 1  Waiting for TCPC 4 2 TCPC completion 7 (39) 9 (50) 0.50 a P-value based on χ2 test. BDG: bidirectional Glenn procedure; MBT: modified Blalock–Taussig shunt; NP: Norwood-type palliation; SV–PA: systemic ventricle–pulmonary artery; TCPC: total cavopulmonary connection. Open in new tab DISCUSSION This study investigated the impact of the valved conduit on the haemodynamics of the SV–PA shunt concomitant with NP compared with the MBT shunt. The leaflets of the valve made of 0.1-mm-thick ePTFE membrane were directly sewn on the inside of the ePTFE grafts. To our knowledge, this study is the first to describe the clinical outcomes of this type of ePTFE valved conduit applied to the shunt as part of the Norwood procedure. Several large-sized studies have reported the advantages of the non-valved RV–PA shunt over the MBT shunt. The SVR trial that compared the outcomes for 549 infants randomized to RV–PA and MBT shunt demonstrated that transplantation-free survival at 12 months after randomization was higher with the RV–PA than with the MBT shunt [1]. In a propensity score-matched cohort study of 169 pairs, overall and transplant-free survival at 6 years were significantly better after RV–PA than after MBT shunt [2]. There are mainly 2 theoretical advantages of an RV–PA shunt in terms of haemodynamics. First, the elimination of diastolic runoff stabilizes systemic circulation and reduces the potential for coronary steal, potentially leading to a lower rate of perioperative adverse events and inter-stage mortality. Second, avoiding ventricular volume overload due to excessive pulmonary flow also improves inter-stage survival and preserves right ventricular function at the point of BDG. If that theory is true, a reduction in diastolic regurgitation through the RV–PA conduit brought by adding a valve could further improve the ventricular function and inter-stage outcomes in patients with an RV–PA shunt. In our series, the results did not show significant differences between the groups with regard to serious adverse events within 30 days or overall survival rate at 5 years after NP; however, the present study was small and did not have adequate statistical power to show differences in these 2 end points. Meanwhile, on the pre-BDG assessment, end-diastolic volume index was significantly lower and EF was significantly greater in the valved SV–PA than in the MBT group. The results suggested that the valved conduit could improve the haemodynamics after NP and preserve ventricular function until BDG. Conversely, adding a valve in a conduit may accelerate stenosis by degeneration of the valve itself, thrombosis, or neointimal thickening in the conduit. The abovementioned randomized study reported that the 12-month rate of unintended interventions, consisting primarily of balloon dilation and stent placement, was higher for the RV–PA shunt group, even though the RV–PA shunt in the study was non-valved. It is possible that regurgitation in the non-valved conduit generates turbulent flow during the diastolic phase and increases shear stress on its inner surface. As a result, neointimal thickening is induced and accelerates stenosis. It is necessary to control pulmonary regurgitation to prevent turbulent flow. Although the difference did not reach significance, interventions within 30 days of NP were observed only in the MBT group in our series. No statistically significant difference was observed in the frequency of overall interventions between the groups. Regarding valve stenosis, Qp/Qs was certainly lower in the valved SV–PA group but not sufficiently low to increase the need for interventions, suggesting that the ePTFE valve did not evidently accelerate conduit stenosis. We previously reported the outcome of small-sized valved conduits of the same type as that here. The rate of freedom from conduit reintervention for conduit-related reasons was >80% at 2 years [12]; hence, stenosis in the valved conduit would become less of an issue during such a short period until BDG. Conflicting views exist concerning the association of the RV–PA shunt with PA development. Some report good PA development, and others report poor PA development [17, 18]; thus, the impact of the RV–PA shunt on PA growth remains controversial. Inadequate PA development may be related to the large number of interventions for stenosis in patients with RV–PA shunt. Furthermore, the regurgitant flow itself or decreased diastolic pressure in the PAs may cause negative effects on their development. Conversely, the reports concluding that the RV–PA shunt has favourable effects on PA growth argue that pulsatile blood flow would create expansion and recoil of the PAs, promoting better distal growth [16, 19]. A decrease in pulmonary pulse pressure and pulmonary blood flow caused by conduit stenosis was found to impair PA development [20]. Here, the PA index was comparable between the groups. This finding suggests that the valved conduit as the SV–PA shunt would not interfere with PA development. In addition, it supports the hypothesis that maintaining the diastolic and pulse pressures in the PA has an important impact on PA development. RV–PA shunts using valved femoral vein homograft or composite conduits created by sewing the ePTFE tube to several types of homograft valves (pulmonary valve, femoral vein and others) were recently reported [3–6]. A comparison of 100 patients with a composite valved conduit and 30 patients with a non-valved conduit showed that fewer events were observed in cases of valved conduits than in those of non-valved conduits, but there was no difference in survival and echocardiographic parameters of right ventricular function at pre-BDG evaluation [5]. The patients with a valved conduit underwent more interventions in the inter-stage period, although this difference was not significant [6]. Degeneration and stenosis of the segment of the valved homograft remained a problem. In contrast, we focussed on the properties of ePTFE, such as its biologically inert nature and low tissue affinity, i.e. its hydrophobicity and a microporous structure preventing cellular invasion [21]. Subsequently, we developed fan-shaped leaflets made of 0.1-mm-thick ePTFE membrane and the ePTFE valved conduits equipping those leaflets. Furthermore, we developed the technology of adding bulging sinuses to conduits designed to imitate the sinus of Valsalva [9]. Those bulging sinuses are expected to secure the effective orifice area of the valve and to generate vortex flow helping in quick valve closure. In addition, our ePTFE valved conduit has a smooth inner surface without calibre irregularity between the homograft and prosthetic graft, unlike the above composite grafts, so that turbulent flow accelerating stenosis was suppressed. The grafts used in our conduits were non-ringed because of processing of the valve and sinuses; therefore, we did not apply the ‘Dunk’ technique in the proximal anastomosis [22]. In summary, the ePTFE valved conduit used as the SV–PA shunt improved postoperative and inter-stage mortality and preserved ventricular function until BDG. PA growth was equivalently promoted in the 2 groups and unintended intervention in the inter-stage period was not increased in the valved SV–PA group, unlike in other studies. We conclude that these favourable effects were obtained by the valved conduit reducing pulmonary regurgitation. Limitations This study had some limitations. First, the sample size was small limiting the statistical power of the comparison. Due to the small sample size, only 8 events were observed and no differences in early mortality and survival rate could be detected. Thus, these results require cautious interpretation. Second, this was a retrospective study without randomization. The decision on the type and size of shunt was made at the discretion of the surgeon. Although differences in baseline characteristics did not indicate bias, selection bias may have played a role in the results of this study. Third, we tended to actively apply bilateral PA banding to a wide range of patients and performed bougie dilation or patch augmentation of the PAs during Norwood procedure if stenosis remained after PA debanding. It is possible that this surgical angioplasty had an impact on PA development. Finally, we did not evaluate the effect of only the valve-added SV–PA shunt because it was not a pure comparison between a valved SV–PA shunt and a non-valved one. CONCLUSION A valved SV–PA shunt using the ePTFE valved conduit preserved ventricular function and would promote good PA growth by controlling regurgitant flow, which was comparable to the MBT shunt and associated with improved postoperative and inter-stage mortality. Further accumulation of experiences and follow-up are required, and studies comparing the valved with non-valved SV–PA shunts should be conducted to reveal the effectiveness of the valve in the SV–PA shunt. Conflict of interest: Masaaki Yamagishi has received professional fees from W.L. Gore & Associates Inc., as a consultant. All other authors declared no conflict of interest. Author contributions Shuhei Fujita: Data curation; Investigation; Writing—original draft. Masaaki Yamagishi: Conceptualization; Project administration; Supervision; Validation; Writing—review & editing. Yoshinobu Maeda: Investigation. Keiichi Itatani: Investigation. Satoshi Asada: Investigation. Hisayuki Hongu: Investigation. Eijiro Yamashita: Investigation. Yuji Takayanagi: Data curation. Hiroki Nakatsuji: Investigation. Hitoshi Yaku: Supervision. Presented at the 33rd Annual Meeting of the European Association for Cardio-Thoracic Surgery, Lisbon, Portugal, 3–5 October 2019. REFERENCES 1 Ohye RG , Sleeper LA , Mahony L , Newburger JW , Pearson GD , Lu M et al. Comparison of shunt types in the Norwood procedure for single-ventricle lesions . N Engl J Med 2010 ; 362 : 1980 – 92 . 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Protein adsorption on PTFE surface modified by ArF excimer laser treatment . J Adhes Sci Technol 2004 ; 18 : 1545 – 55 . Google Scholar Crossref Search ADS WorldCat 22 Tweddell JS , Mitchell ME , Woods RK , Spray TL , Quintessenza JA. Construction of the right ventricle-to-pulmonary artery conduit in the Norwood: the “Dunk” technique . Oper Tech Thorac Cardiovasc Surg 2012 ; 17 : 81 – 98 . Google Scholar Crossref Search ADS WorldCat Abbreviations Abbreviations BDG Bidirectional Glenn procedure EF Ejection fraction ePTFE Expanded polytetrafluoroethylene MBT Modified Blalock–Taussig shunt NP Norwood-type palliation PA Pulmonary artery RV–PA Right ventricle–pulmonary artery SV–PA Systemic ventricle–pulmonary artery TCPC Total cavopulmonary connection © The Author(s) 2020. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
TI - The effect of a valved small conduit on systemic ventricle–pulmonary artery shunt in the Norwood-type palliation
JF - European Journal of Cardio-Thoracic Surgery
DO - 10.1093/ejcts/ezz377
DA - 2020-06-01
UR - https://www.deepdyve.com/lp/oxford-university-press/the-effect-of-a-valved-small-conduit-on-systemic-ventricle-pulmonary-Kv4zBRQpAP
DP - DeepDyve
ER -