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Sano Shunt
Randy R. Richardson, MD; Prakash M. Masand, MD
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KEY FACTS

  • Terminology

    • Imaging

      • Top Differential Diagnoses

        TERMINOLOGY

        • Synonyms

          • Right ventricle-pulmonary artery (RV-PA) conduit
        • Definitions

          • Norwood stage 1 involves using main PA to augment ascending aorta in patients with hypoplastic left heart syndrome (HLHS)
            • New source of pulmonary blood flow is required
              • Blalock-Taussig (BT) shunt provides source of pulmonary blood flow from systemic arterial system
              • BT flow is continuous in both systole & diastole
              • Because ~ 75% of coronary blood flow occurs during diastole, coronary steal phenomenon develops
                • Diastolic retrograde flow occurs in coronaries & descending thoracic aorta
                • Resultant coronary insufficiency is theorized to play major role in operative & postoperative morbidity/mortality of stage 1 Norwood with BT shunt
            • Sano conduit (extracardiac conduit between RV & PA) is alternative to modified BT shunt
              • Small ventriculotomy is made in RV outflow tract
              • 4- to 6-mm synthetic graft is anastomosed to RV & PA to left of neoaorta
              • Conduit is nonvalved, thus allowing free regurgitation
          • Typically performed during 1st few days of life
          • Stage 2 Norwood (Glenn anastomosis) typically needs to be performed slightly earlier after Sano shunt than with modified BT shunt in 3- to 6-month timeframe
          • Benefits
            • Elimination of coronary steal phenomenon secondary to reversal of diastolic flow with modified BT shunt
              • Forward flow through shunt only occurs during systole
            • Improved hemodynamic stability postoperatively compared to modified BT shunt
            • Higher rate of transplantation-free survival at 12 months compared with modified BT shunt
            • Nonrandomized & retrospective studies have shown potential benefit in outcomes associated with RV-PA conduit when compared to modified BT shunt
          • One limitation cited in available literature is poor ventricular performance in view of ventriculotomy
            • Current available evidence, although weak, does not show any adverse effects of ventriculotomy on ventricular performance in patients with Sano shunt in short & medium terms

        IMAGING

        • General Features

          • CT Findings

            • MR Findings

              • Echocardiographic Findings

                DIFFERENTIAL DIAGNOSIS

                  Selected References

                  1. Çelik M et al: Alternate approach to hypoplastic left heart syndrome stage 1 surgery. Ann Thorac Surg. 111(3):e173-5, 2021
                  2. Gong CL et al: Impact of confounding on cost, survival, and length-of-stay outcomes for neonates with hypoplastic left heart syndrome undergoing stage 1 palliation surgery. Pediatr Cardiol. 41(5):996-1011, 2020
                  3. Ismail MF et al: Evolution of the Norwood operation outcomes in patients with late presentation. J Thorac Cardiovasc Surg. 159(3):1040-8, 2020
                  4. Carreon CK et al: Pathology of valved venous homografts used as right ventricle-to-pulmonary artery conduits in congenital heart disease surgery. J Thorac Cardiovasc Surg. 157(1):342-50.e3, 2019
                  5. Briceno-Medina M et al: Femoral vein homograft as Sano shunt results in improved pulmonary artery growth after Norwood operation. Cardiol Young. 28(1):118-25, 2018
                  6. Said SM et al: Norwood valved Sano shunt: early reward versus late penalty? J Thorac Cardiovasc Surg. 155(4):1756-7, 2018
                  7. Murtuza B et al: The effect of morphologic subtype on outcomes following the Sano-Norwood procedure. Eur J Cardiothorac Surg. 42(5):787-93, 2012
                  8. Loomba RS et al: Short-term outcome comparison of Norwood procedures with right ventricle to pulmonary artery conduit versus modified Blalock-Taussig shunt: a meta-analysis. Ann Pediatr Cardiol. 4(2):145-9, 2011
                  9. Ohye RG et al: Comparison of shunt types in the Norwood procedure for single-ventricle lesions. N Engl J Med. 362(21):1980-92, 2010
                  10. Raja SG et al: In hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig shunt associated with deleterious effects on ventricular performance? Interact Cardiovasc Thorac Surg. 10(4):620-3, 2010
                  11. Rüffer A et al: The Norwood procedure - does the type of shunt determine outcome? Thorac Cardiovasc Surg. 57(5):270-5, 2009
                  12. Gaca AM et al: Repair of congenital heart disease: a primer-part 1. Radiology. 247(3):617-31, 2008
                  13. Sano S et al: Outcome of right ventricle-to-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome: a multi-institutional study. Ann Thorac Surg. 78(6):1951-7; discussion 1957-8, 2004
                  14. Sano S et al: Right ventricle-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome. J Thorac Cardiovasc Surg. 126(2):504-9; discussion 509-10, 2003
                  Related Anatomy
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                  Related Differential Diagnoses
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                  References
                  Tables

                  Tables

                  KEY FACTS

                  • Terminology

                    • Imaging

                      • Top Differential Diagnoses

                        TERMINOLOGY

                        • Synonyms

                          • Right ventricle-pulmonary artery (RV-PA) conduit
                        • Definitions

                          • Norwood stage 1 involves using main PA to augment ascending aorta in patients with hypoplastic left heart syndrome (HLHS)
                            • New source of pulmonary blood flow is required
                              • Blalock-Taussig (BT) shunt provides source of pulmonary blood flow from systemic arterial system
                              • BT flow is continuous in both systole & diastole
                              • Because ~ 75% of coronary blood flow occurs during diastole, coronary steal phenomenon develops
                                • Diastolic retrograde flow occurs in coronaries & descending thoracic aorta
                                • Resultant coronary insufficiency is theorized to play major role in operative & postoperative morbidity/mortality of stage 1 Norwood with BT shunt
                            • Sano conduit (extracardiac conduit between RV & PA) is alternative to modified BT shunt
                              • Small ventriculotomy is made in RV outflow tract
                              • 4- to 6-mm synthetic graft is anastomosed to RV & PA to left of neoaorta
                              • Conduit is nonvalved, thus allowing free regurgitation
                          • Typically performed during 1st few days of life
                          • Stage 2 Norwood (Glenn anastomosis) typically needs to be performed slightly earlier after Sano shunt than with modified BT shunt in 3- to 6-month timeframe
                          • Benefits
                            • Elimination of coronary steal phenomenon secondary to reversal of diastolic flow with modified BT shunt
                              • Forward flow through shunt only occurs during systole
                            • Improved hemodynamic stability postoperatively compared to modified BT shunt
                            • Higher rate of transplantation-free survival at 12 months compared with modified BT shunt
                            • Nonrandomized & retrospective studies have shown potential benefit in outcomes associated with RV-PA conduit when compared to modified BT shunt
                          • One limitation cited in available literature is poor ventricular performance in view of ventriculotomy
                            • Current available evidence, although weak, does not show any adverse effects of ventriculotomy on ventricular performance in patients with Sano shunt in short & medium terms

                        IMAGING

                        • General Features

                          • CT Findings

                            • MR Findings

                              • Echocardiographic Findings

                                DIFFERENTIAL DIAGNOSIS

                                  Selected References

                                  1. Çelik M et al: Alternate approach to hypoplastic left heart syndrome stage 1 surgery. Ann Thorac Surg. 111(3):e173-5, 2021
                                  2. Gong CL et al: Impact of confounding on cost, survival, and length-of-stay outcomes for neonates with hypoplastic left heart syndrome undergoing stage 1 palliation surgery. Pediatr Cardiol. 41(5):996-1011, 2020
                                  3. Ismail MF et al: Evolution of the Norwood operation outcomes in patients with late presentation. J Thorac Cardiovasc Surg. 159(3):1040-8, 2020
                                  4. Carreon CK et al: Pathology of valved venous homografts used as right ventricle-to-pulmonary artery conduits in congenital heart disease surgery. J Thorac Cardiovasc Surg. 157(1):342-50.e3, 2019
                                  5. Briceno-Medina M et al: Femoral vein homograft as Sano shunt results in improved pulmonary artery growth after Norwood operation. Cardiol Young. 28(1):118-25, 2018
                                  6. Said SM et al: Norwood valved Sano shunt: early reward versus late penalty? J Thorac Cardiovasc Surg. 155(4):1756-7, 2018
                                  7. Murtuza B et al: The effect of morphologic subtype on outcomes following the Sano-Norwood procedure. Eur J Cardiothorac Surg. 42(5):787-93, 2012
                                  8. Loomba RS et al: Short-term outcome comparison of Norwood procedures with right ventricle to pulmonary artery conduit versus modified Blalock-Taussig shunt: a meta-analysis. Ann Pediatr Cardiol. 4(2):145-9, 2011
                                  9. Ohye RG et al: Comparison of shunt types in the Norwood procedure for single-ventricle lesions. N Engl J Med. 362(21):1980-92, 2010
                                  10. Raja SG et al: In hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig shunt associated with deleterious effects on ventricular performance? Interact Cardiovasc Thorac Surg. 10(4):620-3, 2010
                                  11. Rüffer A et al: The Norwood procedure - does the type of shunt determine outcome? Thorac Cardiovasc Surg. 57(5):270-5, 2009
                                  12. Gaca AM et al: Repair of congenital heart disease: a primer-part 1. Radiology. 247(3):617-31, 2008
                                  13. Sano S et al: Outcome of right ventricle-to-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome: a multi-institutional study. Ann Thorac Surg. 78(6):1951-7; discussion 1957-8, 2004
                                  14. Sano S et al: Right ventricle-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome. J Thorac Cardiovasc Surg. 126(2):504-9; discussion 509-10, 2003