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THE ASSISTED BIDIRECTIONAL GLENN: AN IN VITRO AND IN SILICO STUDY OF A SURGICAL APPROACH FOR FIRST STAGE SINGLE VENTRICLE HEART PALLIATION
A518 JACC March 17, 2015 Volume 65, Issue 10S
Congenital Heart Disease The Assisted Bidirectional Glenn: An In Vitro and In Silico Study of a Surgical Approach for First Stage Single Ventricle Heart Palliation Poster Contributions Poster Hall B1 Saturday, March 14, 2015, 10:00 a.m.-10:45 a.m. Session Title: Clinical Outcomes in Single Ventricle Patients Abstract Category: 11. Congenital Heart Disease: Pediatric Presentation Number: 1118-328 Authors: Richard Figliola, Mahdi Esmaily-Moghadam, Jian Zhou, Tain-Yen Hsia, Alison Marsden, Clemson University, Clemson, SC, USA, University of California, San Diego, San Diego, CA, USA Background: Outcomes following a modified Blalock-Taussig shunt (mBTS) in neonates with single ventricle physiology remain unsatisfactory. However, initial palliation with a superior cavopulmonary connection, such as a bidirectional Glenn, is discouraged due to concerns of inadequate pulmonary blood flow (PBF). We developed both experimental and numerical circulation models to test the feasibility of a novel surgical approach, whereby the flow in the bidirectional Glenn is ‘assisted’ by shunting high-energy flow from the systemic circulation.
Methods: Realistic three-dimensional anatomical models of the neonatal mBTS and Glenn surgical sites were created and coupled with validated hydraulic multi-scale models of the complete circulation using parameters based on measurements from 23 single ventricle neonates. An ‘assisted’ bidirectional Glenn (ABG) model was also created and consisted of a shunt between the right innominate artery and superior vena cava (SVC) with a flow reducing clip near the SVC anastomosis to create a Venturi effect. Both in vitro and in silico studies were executed. Two values of pulmonary vascular resistance (PVR), normal and elevated (PVR = 2.3 and 7 WU), were tested.
Results: The experimental and numerical results were in close agreement. The ABG provided the highest systemic oxygen saturation and oxygen delivery at both PVR levels. In addition to achieving nearly 30% higher PBF than the Glenn with 14% higher oxygen delivery than the mBTS, the ABG produced lower single ventricular workload than mBTS. SVC pressure was highest in the ABG model at high PVR (ABG:15, Glenn:11, mBTS: 3 mmHg), but at low PVR, the SVC pressure was significantly reduced (ABG:8, Glenn:6, mBTS: <3 mmHg). Experimental results using geometric variations, including shunt to venturi diameter ratio and shunt angle, show promise in lowering SVC pressures further. Conclusion: The ABG approach increases PBF with a modest increase in SVC and pulmonary arterial pressure. While the results demonstrate the conceptual feasibility of the ABG circulation with physical verification, further technical refinements including animal models are necessary.
Congenital Heart Disease The Assisted Bidirectional Glenn: An In Vitro and In Silico Study of a Surgical Approach for First Stage Single Ventricle Heart Palliation Poster Contributions Poster Hall B1 Saturday, March 14, 2015, 10:00 a.m.-10:45 a.m. Session Title: Clinical Outcomes in Single Ventricle Patients Abstract Category: 11. Congenital Heart Disease: Pediatric Presentation Number: 1118-328 Authors: Richard Figliola, Mahdi Esmaily-Moghadam, Jian Zhou, Tain-Yen Hsia, Alison Marsden, Clemson University, Clemson, SC, USA, University of California, San Diego, San Diego, CA, USA Background: Outcomes following a modified Blalock-Taussig shunt (mBTS) in neonates with single ventricle physiology remain unsatisfactory. However, initial palliation with a superior cavopulmonary connection, such as a bidirectional Glenn, is discouraged due to concerns of inadequate pulmonary blood flow (PBF). We developed both experimental and numerical circulation models to test the feasibility of a novel surgical approach, whereby the flow in the bidirectional Glenn is ‘assisted’ by shunting high-energy flow from the systemic circulation.
Methods: Realistic three-dimensional anatomical models of the neonatal mBTS and Glenn surgical sites were created and coupled with validated hydraulic multi-scale models of the complete circulation using parameters based on measurements from 23 single ventricle neonates. An ‘assisted’ bidirectional Glenn (ABG) model was also created and consisted of a shunt between the right innominate artery and superior vena cava (SVC) with a flow reducing clip near the SVC anastomosis to create a Venturi effect. Both in vitro and in silico studies were executed. Two values of pulmonary vascular resistance (PVR), normal and elevated (PVR = 2.3 and 7 WU), were tested.
Results: The experimental and numerical results were in close agreement. The ABG provided the highest systemic oxygen saturation and oxygen delivery at both PVR levels. In addition to achieving nearly 30% higher PBF than the Glenn with 14% higher oxygen delivery than the mBTS, the ABG produced lower single ventricular workload than mBTS. SVC pressure was highest in the ABG model at high PVR (ABG:15, Glenn:11, mBTS: 3 mmHg), but at low PVR, the SVC pressure was significantly reduced (ABG:8, Glenn:6, mBTS: <3 mmHg). Experimental results using geometric variations, including shunt to venturi diameter ratio and shunt angle, show promise in lowering SVC pressures further. Conclusion: The ABG approach increases PBF with a modest increase in SVC and pulmonary arterial pressure. While the results demonstrate the conceptual feasibility of the ABG circulation with physical verification, further technical refinements including animal models are necessary.