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.