Ann Thorac Surg 2005;80:1647-1651
© 2005 The Society of Thoracic Surgeons
Original article: Cardiovascular
Ascending Aortic Extension for Enlargement of the Aortopulmonary Space in Children with Pulmonary Artery Stenosis
Craig J. Baker, MD,
Winfield J. Wells, MD
*
,
Chris A. Derby, MD,
Suzanne Rizi, BS, MPH,
Vaughn A. Starnes, MD
Department of Cardiothoracic Surgery, University of Southern California, Childrens Hospital of Los Angeles, Los Angeles, California
Accepted for publication April 26, 2005.
* Address correspondence to Dr Wells, Division of Cardiothoracic Surgery, Childrens Hospital of Los Angeles, 4650 Sunset Blvd, Mailbox 66, Los Angeles, CA 90054 (Email: wwells{at}chla.usc.edu).
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Abstract
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BACKGROUND: Complex reconstruction of the aorta can be complicated by compression within the aortopulmonary space resulting in airway or pulmonary artery narrowing. Pulmonary artery compression is especially problematic in children with single ventricle physiology in which an increase in pulmonary vascular resistance may impair systemic venous flow and reduce cardiac output.
METHODS: We operated on 7 patients (mean age, 2.9 years) with pulmonary artery stenosis presenting after a complex neonatal aortic reconstruction. All 7 patients underwent aortic extension with a polytetrafluoroethylene interposition graft and homograft patch angioplasty of the pulmonary artery to open the aortopulmonary space and relieve pulmonary artery narrowing. Five patients (hypoplastic left heart syndrome, n = 2; transposition of the great arteries with tricuspid atresia and aortic hypoplasia, n = 1; double outlet right ventricle with aortic hypoplasia, n = 2) had previously undergone first stage repairs for single ventricle morphology. Two of the patients had multiple interim procedures, including placement of bilateral pulmonary artery stents, prior to our repair.
RESULTS: There was 1 early death secondary to fungal sepsis. Six patients were discharged from the hospital. There was 1 late, noncardiac death from aspiration pneumonia in a patient with a severe craniofacial defect. Follow-up echocardiograms in the intermediate term have demonstrated relief of pulmonary artery narrowing and unobstructed aortic flow.
CONCLUSIONS: Aortic extension is an option in children with pulmonary artery compression of structures in the aortopulmonary space after complex aortic reconstruction.
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Introduction
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Reconstruction of the aorta in neonates with complex congenital heart disease has become increasingly feasible due to improved operative technique and perioperative care. A number of authors have reported on the problem of airway obstruction (usually left bronchus) associated with narrowing of the aortopulmonary space (APS) after aortic reconstruction [1–8]. In addition, compression from the reconstructed aorta can potentially impinge on the pulmonary artery (PA). This is especially problematic in children with single ventricle physiology who must eventually rely on undistorted pulmonary artery anatomy and low resistance to maintain acceptable venous pressures.
Limited information exists on operative relief of APS vascular compression after aortic arch reconstruction. We report our experience with 7 children who have undergone aortic extension to open the APS because of pulmonary artery compression after Damus-Kaye-Stansel, Norwood, or other complex aortic arch reconstructions.
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Patients and Methods
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Patients
Between August 2002 and October 2004, 7 children (mean age, 2.9 years; range, 7 months to 7 years) underwent aortic extension by polytetrafluoroethylene interposition grafting and homograft patch angioplasty of the pulmonary artery to open the APS and correct the PA stenosis. The institutional review board granted approval for retrospective review of these patients' data. The mean interval between the original surgery that included arch repair and the need for aortic extension was 2.9 ± 2.5 years. The initial diagnosis and previous surgeries are included in Table 1. Prior to aortic extension, the patients had preoperative imaging studies including echocardiography (6 patients), catheterization (5 patients), and magnetic resonance imaging (4 patients) confirming PA narrowing as demonstrated in Figure 1, and compression of the aortopulmonary window (Figs 2–4).
Three patients, initially operated on at outside centers, had undergone additional surgeries after their primary repair. Two of these patients had multiple additional interventions including placement of bilateral PA stents. Concomitant repairs were carried out at the time of the aortic extension operation as noted in Table 2.
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Fig 3. Compression of the pulmonary artery by magnetic resonance imaging (patient 7). (LPA = left pulmonary artery; PA = pulmonary artery.)
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Fig 4. Reconstructed magnetic resonance imaging with removal of aortic arch demonstrating the course of the stenotic pulmonary artery (patient 7). (LPA = left pulmonary artery; PA = pulmonary artery.)
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Surgical Procedure
Patients underwent redo sternotomy and cardiopulmonary bypass (mean cardiopulmonary bypass time, 84.16 ± 19.8 min). In 6 cases, a period of hypothermic circulatory arrest was used (mean hypothermic circulatory arrest time, 28.6 ± 18.5 min). The aorta was transected and the PA was augmented using a pulmonary homograft patch. The patients with previously placed stents had augmentation of both pulmonary arteries. The aorta was reconstructed with a short polytetrafluoroethylene interposition graft to open the aortopulmonary space (Fig 5). A 16-mm graft was placed in all but 2 patients in whom 18 and 24 mm grafts were used. Concomitant repairs were performed after the interposition graft was placed and the patients were returned to full flow cardiopulmonary bypass.
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Results
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There was 1 hospital death secondary to fungal sepsis. All other patients were discharged home. Six months after the operation, a noncardiac death due to aspiration pneumonia occurred in a patient with multiple congenital anomalies including severe craniofacial malformations and seizure disorder. A patient who had undergone a Fontan at the time of aortic extension returned several weeks after discharge with a left pleural effusion and paretic left hemidiaphragm. He underwent diaphragm plication and has subsequently done well. These complications are included in Table 2.
Recent follow-up echocardiograms were carried out in all surviving patients (mean follow-up, 12.31 ± 4.13 months). Low velocity pulmonary flow without obstruction was found in all patients. A pre-Fontan catheterization was performed in 1 patient (patient 4) who had the aortic extension procedure at the time of the Glenn procedure (Fig 6).
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Fig 6. Postoperative angiogram demonstrating the aortic extension performed at the time of the Glenn procedure (patient 4).
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Comment
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Compression within the aortopulmonary space has the potential to cause PA obstruction and an increase in pulmonary vascular resistance. A pincher-type mechanism between the base of the heart and the proximal descending aorta results in variable amounts of compression throughout the cardiac cycle to structures contained within this area. This complication is of particular concern in patients with single ventricle physiology who will go on to total cavopulmonary connection. This is because PA stenosis may cause increased systemic venous pressure, which is associated with poor outcome [9].
The usual approach to aortic compression of structures in the APS has been aortopexy [3, 5]. However, anterior suspension of the aorta to the chest wall may not be successful in patients with complex aortic reconstructions in which the main PA has been anastomosed to the transverse aortic arch such as in stage 1 Norwood or Damus-Kaye-Stansel. In such cases the pathophysiology may be foreshortening of the aortic arch, which is not amenable to suspension. In addition, many patients with complex arch reconstructions will go on to a total cavopulmonary connection repair requiring two subsequent sternotomies, and aortopexy could complicate later sternal re-entry. The ascending aortic extension technique was undertaken to address these problems as lengthening the ascending aorta relieves compression within the aortopulmonary space.
Aortic lengthening procedures have been previously described. Hopkins and colleagues [10] reported on 3 patients undergoing complex pulmonary unifocalization procedures [10]. The aorta was extended to create space for the new bifurcated homograft pulmonary artery reconstruction. Curran and colleagues [11] utilized ascending aortic extension at the time of ventricular-to-pulmonary artery conduit replacement associated with long segment pulmonary artery stenosis. Mitchell and colleagues [8] reported main pulmonary artery autograft aortic extension to relieve bronchial compression after repair of interrupted aortic arch.
Another approach to the problem of vascular compression in the APS has been percutaneous deployment of a stent at the site of PA narrowing. Shaffer and colleagues [12] has summarized the favorable outcomes of the Food and Drug Administration trials utilizing this technique in older children and young adults (mean age, 10.5 years). The limitations of this technology in younger and smaller patients such as those reported in this series were noted. However, Moore and colleagues [13] did report on 8 younger patients (mean age, 27 months; mean weight, 11.4 kg) who each had proximal left PA stenosis after a bi-directional Glenn procedure and who each successfully underwent stent placement prior to the Fontan procedure. There was no specific mention of narrowing of the APS in any of the cases. We have concern that in the face of aortic compression, PA stenting may lead to erosion of the thin pulmonary arterial wall with serious consequences. In 1 of our patients, PA stents were found to have eroded through the vessel wall, as well as distorting the main PA and pulmonary valve. Given these potential problems in younger patients, we have preferred to correct PA stenosis by patch angioplasty rather than stenting.
Although follow-up in this series is limited, echocardiograms have demonstrated relief of pulmonary stenosis in surviving patients and unrestricted aortic flow. Although the grafts used for aortic extension are smaller than the normal adult arch, we expect no important gradient to develop across these short segments. Recently we have been utilizing magnetic resonance imaging preoperatively to define the three-dimensional relationships of the vascular and airway structures contained within the APS. We believe this is the best diagnostic modality and is now the imaging technique of choice at our institution. In addition, we have refined our operative technique more often utilizing isolated cerebral perfusion rather than deep hypothermic circulatory arrest, although the advantage of this technique for shorter durations of deep hypothermic circulatory arrest is not clearly documented.
In summary, aortic extension is an alternative for patients with compression of structures in the aortopulmonary space after complex aortic reconstruction. Further follow-up is needed to validate the long-term effectiveness of this technique.
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References
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Abstract
Introduction
