Abstract 16733: High Death and Re-Intervention Rate in Neonatal Modified Blalock-Taussig Shunts With Concomitant Patent Dutus Artertiosus: Mechanistic Insights Into Competitive Flow and Pulmonary Overcirculation
Background: When palliating neonates with cyanotic heart defects with systemic-pulmonary (SP) shunts, leaving the ductus arteriosus open may lead to competitive flow and/or pulmonary overcirculation. Competitive flow can cause early shunt obstruction. Pulmonary overcirculation can result in poor oxygen delivery. We reviewed the clinical outcomes in neonates following SP shunts in our institution, and conducted multiscale modeling to assess the fluid dynamics of SP shunt with concomitant PDA.
Methods: Retrospective analysis of 69 neonates over a 7-year period was performed: 23 patients had a SP shunt and PDA (MS), and 46 patients had an isolated SP shunt (SS) with PDA ligation. Nearly all patients received modified Blalock-Taussig shunts (MBTS). Patients following Norwood procedure were excluded. Median postoperative PDA diameter was 2.7mm in MS patients. Primary endpoints of death and shunt intervention were assessed. Following the clinical analysis, multiscale models of a 3.5mm MBTS with and without a PDA were constructed. Simulations examine flow dynamics, and predict clinically relevant outcomes such as oxygen delivery.
Results: There was a significantly higher incidence of shunt thrombosis within 3 months in MS vs. SS patients (34.8% vs. 2.2%; p=0.0004). Moreover, the combined endpoint of 30-day mortality/shunt intervention was significantly higher in the MS patients (16% vs. 6%; p<0.01).
Computational simulations showed that in patients with a 3.5mm MBTS and a PDA, despite higher Qp:Qs and systemic oxygen saturation, systemic and coronary oxygen deliveries were lower than shunt only patients. There is also reduced flow velocity magnitude and increased particle residence time within the MBTS (Fig).
Conclusions: When a PDA is left open following SP shunt construction in a neonate, worse clinical outcomes occur. Computer simulations suggest that both pulmonary overcirculation and competitive flow characteristics may contribute to this observation.
Author Disclosures: B. Murtuza: None. M. Esmaily Moghadam: None. A. Marsden: None.
This research has received full or partial funding support from the American Heart Association.
- © 2014 by American Heart Association, Inc.