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
Çelik M et al: Alternate approach to hypoplastic left heart syndrome stage 1 surgery. Ann Thorac Surg. 111(3):e173-5, 2021
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
Ismail MF et al: Evolution of the Norwood operation outcomes in patients with late presentation. J Thorac Cardiovasc Surg. 159(3):1040-8, 2020
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
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
Said SM et al: Norwood valved Sano shunt: early reward versus late penalty? J Thorac Cardiovasc Surg. 155(4):1756-7, 2018
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
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
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
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
Rüffer A et al: The Norwood procedure - does the type of shunt determine outcome? Thorac Cardiovasc Surg. 57(5):270-5, 2009
Gaca AM et al: Repair of congenital heart disease: a primer-part 1. Radiology. 247(3):617-31, 2008
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
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
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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
Çelik M et al: Alternate approach to hypoplastic left heart syndrome stage 1 surgery. Ann Thorac Surg. 111(3):e173-5, 2021
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
Ismail MF et al: Evolution of the Norwood operation outcomes in patients with late presentation. J Thorac Cardiovasc Surg. 159(3):1040-8, 2020
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
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
Said SM et al: Norwood valved Sano shunt: early reward versus late penalty? J Thorac Cardiovasc Surg. 155(4):1756-7, 2018
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
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
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
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
Rüffer A et al: The Norwood procedure - does the type of shunt determine outcome? Thorac Cardiovasc Surg. 57(5):270-5, 2009
Gaca AM et al: Repair of congenital heart disease: a primer-part 1. Radiology. 247(3):617-31, 2008
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
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
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