4.5-mm “Ready-Made” Conduit for Primary Chest Closure After Norwood Procedure

The Norwood procedure with the right ventricle–to–pulmonary artery (RV-PA) conduit has been the standard procedure for hypoplastic left heart syndrome. However, postoperative management can be challenging related to finding the correct balance between pulmonary and systemic blood flow. One can use hemostatic clips on the RV-PA conduit to temporarily restrict pulmonary blood flow. However, the hemodynamics would become unstable after clip removal. Here we describe a novel technique that allows precise pulmonary blood flow without the addition and removal of clips on the RV-PA conduit, allowing primary chest closure after the Norwood procedure. The Norwood procedure with the right ventricle–to–pulmonary artery (RV-PA) conduit has been the standard procedure for hypoplastic left heart syndrome. However, postoperative management can be challenging related to finding the correct balance between pulmonary and systemic blood flow. One can use hemostatic clips on the RV-PA conduit to temporarily restrict pulmonary blood flow. However, the hemodynamics would become unstable after clip removal. Here we describe a novel technique that allows precise pulmonary blood flow without the addition and removal of clips on the RV-PA conduit, allowing primary chest closure after the Norwood procedure. During the last decade, the outcomes of the Norwood procedure have greatly improved by the introduction of the right ventricle–to–pulmonary artery (RV-PA) conduit. Murtuza and associates1Murtuza B. Jones T. Barron D. Brawn W. Temporary restriction of right ventricle–pulmonary artery conduit flow using haemostatic clips following Norwood I reconstruction: potential for improved outcomes.Interact Cardiovasc Thorac Surg. 2012; 14: 327-329Crossref PubMed Scopus (10) Google Scholar introduced temporary restriction of RV-PA conduit flow using hemostatic clips to balance the pulmonary-systemic blood flow ratio. However, it is difficult for the pediatric cardiac surgeon to determine how many clips are needed on the RV-PA conduit to prevent pulmonary overcirculation intraoperatively.2Kuduvalli M. McLaughlin K. Trivedi D. Pozzi M. Norwood-type operation with adjustable systemic-pulmonary shunt using hemostatic clip.Ann Thorac Surg. 2001; 72: 634-635Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar,3Schmid F. Kampmann C. Kuroczynski W. et al.Adjustable tourniquet to manipulate pulmonary blood flow after Norwood operations.Ann Thorac Surg. 1999; 68: 2306-2309Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar There are also risks of blood clotting in the conduit or oxygen desaturations by tightening the RV-PA conduit too much. Moreover, if the temporary clips are removed during delayed chest closure, the patient is again at risk of pulmonary overcirculation, causing hemodynamic instability. This article describes the precise “ready-made” 4.5-mm RV-PA conduit that does not require clip removal, allowing selected patients to undergo primary chest closure during the Norwood procedure for hypoplastic left heart syndrome. General anesthesia is established through an endotracheal tube, central venous line placement, and right radial arterial line placement for the Norwood procedure. We create a precisely measured expanded polytetrafluoroethylene (ePTFE) graft (W. L. Gore & Associates) to the size of 4.5 mm for neonates weighing between 3.0 and 3.5 kg before median sternotomy. We currently select a 4-mm ePTFE graft as RV-PA conduit for patients weighing less than 3.0 kg and a 5-mm ePTFE graft for patients weighing more than 3.5 kg. Because there is no 4.5-mm ePTFE graft on the market, we necessarily make it. We put a 4.5-mm probe inside a 5-mm ePTFE graft and pinch the wall of the graft between the probe and the graft (Figure 1-1; Video). We then obliquely apply several small titanium clips (Weck Horizon; Teleflex) on the space (Figures 1-2, 1-3). We perform the Norwood procedure employing selective antegrade cerebral perfusion with systemic cooling to 25 °C. We use the 4.5-mm ePTFE graft at the position of the RV-PA conduit. During 2020 and 2021, we have used this 4.5-mm ready-made RV-PA conduit for 3 patients who have weighed 3.18 kg, 3.17 kg, and 3.36 kg (Figure 2). Each of these patients required only less than 0.03 μg/kg per minute of epinephrine and less than 5 μg/kg per minute of dopamine to achieve systolic arterial blood pressures between 60 and 80 mm Hg in the immediate postoperative period. To keep oxygen saturations in the goal range of 75% to 85%, we needed only 0.4 fraction of inspired oxygen or less on the ventilator. Even with clips in place on the RV-PA conduit, the patients’ oxygen saturation remained between 75% and 85% on room air after extubation. We were able to perform delayed sternal chest closure 17 hours after Norwood procedure for the first patient and primary chest closure in the operating room for the last 2 patients. It was not necessary to remove any clips from the 4.5-mm RV-PA conduit at the time of chest closure. We extubated all 3 patients within 24 hours after the chest closure. Aspirin was started on postoperative day 1 for anticoagulation. All patients were discharged home with appropriate oxygen saturation on room air. No cardiac catheter interventions for the conduit were needed for any of the patients before the Glenn procedure. There were no thromboembolic complications with use of the 4.5-mm RV-PA conduit at interstage. Cardiac catheterization before the Glenn procedure demonstrated clear patency of the RV-PA conduit. We have completed the Glenn procedure for each of these patients at 4 months of age.Figure 2The 4.5-mm ready-made right ventricle–to–pulmonary artery conduit was applied in place.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The management of maintaining adequate pulmonary-to-systemic blood flow after the Norwood procedure is a key factor to preserving stable hemodynamics. In 2012, Murtuza and associates1Murtuza B. Jones T. Barron D. Brawn W. Temporary restriction of right ventricle–pulmonary artery conduit flow using haemostatic clips following Norwood I reconstruction: potential for improved outcomes.Interact Cardiovasc Thorac Surg. 2012; 14: 327-329Crossref PubMed Scopus (10) Google Scholar described lower 30-day mortality by temporarily restricting pulmonary blood flow through the application of hemostatic clips on the RV-PA conduit. The size of the tightened RV-PA conduit is critical to achieving this balance. However, it is difficult for the pediatric cardiac surgeon to eyeball the precise size of the RV-PA conduit without experience. If the RV-PA conduit is made too small with the clips, there are risks of oxygen desaturation and thrombosis in the conduit without any benefit to improved hemodynamics. Moreover, the temporary clips must be removed before chest closure, which may then again cause hemodynamic instability for patients. Our 4.5-mm ready-made RV-PA conduit can provide a remarkably accurate size that has many advantages: it is easy to make, provides an accurate conduit size, and is reproducible; the clips do not need to be removed before chest closure; Norwood procedure time is not extended because the conduit is made before the incision, therefore becoming ready-made; primary chest closure is more likely; and clips are secure because of the longer landing zone but are still able to be removed in the cardiac catheterization laboratory. The essence of this technique is to use a 4.5-mm probe inside a 5-mm ePTFE graft and to put clips on the conduit obliquely vs the perpendicular approach, which allows the clips to easily fall off the shunt (Figure 3). In conclusion, this 4.5-mm ready-made RV-PA conduit appears to provide a precise balance between the systemic and pulmonary circulations for neonates weighing between 3.0 and 3.5 kg undergoing the Norwood procedure, allowing primary chest closure. The Video can be viewed in the online version of this article [https://doi.org/10.1016/j.atssr.2023.07.005] on http://www.annalsthoracicsurgery.org. The authors have no funding sources to disclose.