Expert Techniques: Neonatal Aortic Arch Repair and the Warden Procedure

Patient Selection 

Early surgical correction of ductal-dependent neonatal patients with an aortic coarctation (CoA) and distal arch hypoplasia have emerged as the current standard of care. To begin, the criteria necessitating neonatal aortic arch repair and the Warden procedure (1-5) are summarized. First, ensure that a biventricular repair is deemed possible. Neonates with (1) an aortic arch diameter z-score of <-2.0 or (2) a ratio of the diameter of the transverse arch to the descending aorta of <50 percent or (3) an arch measuring in mm less than the patient’s weight in kg +1 are diagnosed with a hypoplastic aortic arch. Additionally, a pressure gradient of >20mmHg between the upper and lower extremities is viewed as a clinically significant stenosis. Patients with symptoms of hypoperfusion or ductal-dependent perfusion of the lower body require urgent surgical repair. This also applies to patients with findings of impaired left ventricular function in echocardiography. Surgical correction should be performed in a single stage approach, if possible, in patients with an additional anomaly, such as a partial anomalous pulmonary venous connection to the high SVC with or without an associated atrial septal defect (ASD), and evidence of a significant shunt and/or other clinical symptoms. 

Median Sternotomy and Preparations 

Median sternotomy and thymus resection was performed, followed by the opening of the pericardium with collection of an autologous pericardial patch. Careful and complete mobilization of mediastinal structures is essential for optimal correction. Next, was the visualization and preparation of the superior vena cava (SVC), while protecting the right phrenic nerve. After the administration of heparin, the cannulation of the ascending aorta close to the brachiocephalic trunk was performed. Cardiopulmonary bypass was started via a vent catheter in the right atrium and a venous cannula in the inferior vena cava. The superior vena cava was cannulated with a Pacifico venous cannula at the level where the innominate vein joins the SVC. An additional femoral line (2.7 Fr. arterial leadercath) previously placed by the anesthetist was used for retrograde perfusion. This high-pressure line was continuously flushed with 0.8IE/ml heparin through a perfusor running on 2 ml/h until total bypass was established. With both antegrade and retrograde perfusion, the patient was slowly cooled to 24°C. Complete dissection and visualization of the hypoplastic aortic arch, the ductus arteriosus, isthmus region and the descending aorta followed. Thorough identification of the left recurrent laryngeal nerve was ensured. Isolation and division of the ligamentum arteriosum was necessary for the following operative steps. To obtain control, the supraaortic branches were mobilized and controlled with vessel loops. After completion of these steps, the ascending aorta was clamped and cardioplegic arrest was achieved. While cardioplegia was administered, the right atrium was opened. 

Warden Procedure 

At the beginning of the Warden procedure, the superior vena cava wass transected in an oblique manner falling just short at the cavoatrial junction. Once opened, the inflow of the anomalous pulmonary veins into the atrium was inspected. Due to potential obstruction, the junction of the right-sided pulmonary veins and atrium were augmented with a xenopericardial patch with continuous 7/0 Prolene. After this, the sinus venosus defect was enlarged. Then, the atrial septal defect was closed using a second xenopericardial patch with continuous suture. Ensuring unimpeded blood flow through the SVC complete resection of all stenosing trabeculae in the right atrial appendage was necessary. After this, the cephalad portion of the superior vena cava was anastomosed to the right atrial appendage using 7/0 PDS suture. 

Aortic Arch Repair 

To establish combined selective cerebral perfusion and lower body perfusion, the arterial cannula needs to be placed in the brachiocephalic trunk, in addition to the perfusion, through a femoral line. In this patient, ligation of the left subclavian artery was necessary to better mobilize the aorta. Complete resection of the entire isthmus region and all the ductal tissue must be ensured prior to making a longitudinal incision exactly along the inner curvature of the aortic arch. The proximal descending aorta was incised at the most medial aspect of the vessel to create greater diameter. Next, an end-to-side anastomosis of the most lateral aspect of descending aorta with the most lateral aspect of the aortic arch was performed using 7/0 Prolene. The aortic arch was augmented with an autologous pericardial patch using Prolene 7/0 in continuous suture up to the brachiocephalic trunk. 

Weaning of Cardiopulmonary Bypass, Bleeding Control and Closure of Patient 

Deairing maneuvers of all cardiac cavities and the aorta were carried out. The right atrium was closed by continuous suturing. The aortic clamp was released, the body slowly reperfused and rewarmed. After weaning from cardiopulmonary bypass, all bleeding was controlled. Chest tubes and temporary pacemaker wires were placed in the usual manner. Intraoperative invasive pressure measurements in the ascending aorta and the femoral artery were compared for confirmation of a gradient-free connection. Depending on the patient’ss stability, temporary or definite closure of the chest is accomplished. 

Preference Card 

No special or unusual instrumentation or materials need to be used for performing this operation.  

Tips and Pitfalls 

 Despite the technical difficulties, early single-stage surgical correction of ductal-dependent neonates with complex cardiac anomalies should be performed. Both the neonatal aortic arch repair and the Warden procedure are demanding surgical techniques that require special focus on the technical aspects to avoid complications. 

One of the potential challenges of the Warden procedure is avoiding the SVC and pulmonary vein obstruction. Achieving long-term patency (good mobilization) will sometimes require ligation of the azygous vein and is necessary for a tension-free anastomosis. Furthermore, ASD patch oversizing and suturing close to the SVC entrance is to be avoided (5). Excision of all trabeculations within the atrial appendage is essential to allowing unimpeded blood flow (2). Fine interrupted sutures rather than purse-string sutures can be used to repair the venous cannulation side in case of bleeding. When fearing obstruction of the pulmonary venous inflow into the atrium, opt for an extra pericardial patch augmentation of the junction of right-sided pulmonary veins and atrium. To avoid sinoatrial (SA) node dysfunction, an oblique transection of the lower SVC just falling short at the cavoatrial junction is advised. Identification of the SA node artery as a landmark can help when transecting the SVC (5). Shallow bites to protect the SA node are recommended when suturing the intra-atrial baffle. Flawless suturing technique is necessary to avoid anatomic distortion, which may also lead to SA node dysfunction (3).  

The main challenge of neonatal aortic arch repair is avoiding restenosis. Favor timing of the operation at weights >2500g, if possible (1). Complete resection of all ductal tissue and a tension-free anastomosis is key for favorable long-term results. A technical aspect to focus on is the precision of the incision, exactly along the inner curvature of the aortic arch. Moreover, aim for perfect patch length that does not crease or fold after reinitiating antegrade blood flow. To preserve growth, attempt to anastomose as much native tissue as possible. To avoid nerve damage, identify and protect the anatomical structures, such as the recurrent laryngeal nerve during the entire procedure (4). Ensure intraoperative invasive pressure measurement in the ascending aorta and the femoral artery for confirmation of a gradient-free connection before ending the operation. 

References

1. Tsang V, Haapanen H, Neijenhuis R. Aortic Coarctation/Arch Hypoplasia Repair: How Small Is Too Small. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2019;22:10-13. doi:10.1053/j.pcsu.2019.02.011
2. Warden HE, Gustafson RA, Tarnay TJ, Neal WA. An alternative method for repair of partial anomalous pulmonary venous connection to the superior vena cava. Ann Thorac Surg. Dec 1984;38(6):601-5. doi:10.1016/s0003-4975(10)62317-x
3. Griffeth EM, Dearani JA, Mathew J, et al. Early and Late Outcomes of the Warden and Modified Warden Procedure. Ann Thorac Surg. Nov 2022;114(5):1723-1729. doi:10.1016/j.athoracsur.2022.03.032
4. Langley SM, Sunstrom RE, Reed RD, Rekito AJ, Gerrah R. The neonatal hypoplastic aortic arch: decisions and more decisions. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2013;16(1):43-51. doi:10.1053/j.pcsu.2013.01.008
5. Danton MHD, Kesieme EB. Modification of the Warden Procedure for Surgical Repair of Partial Anomalous Pulmonary Venous Connection. World J Pediatr Congenit Heart Surg. Jul 2023;14(4):497-499. doi:10.1177/21501351231168830

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