doi:10.1093/mmcts/mms009 published online 15 May 2012
Pulmonary artery debanding Guido Oppido, Carlo Pace Napoleone, Simone Turci, Emanuela Angeli and Gaetano Gargiulo* Paediatric Cardiac Surgery Unit, S. Orsola-Malpighi Hospital, University of Bologna Medical School, Bologna, Italy; * Corresponding author. Tel: +39-51-6363156; fax: +39-51-6363157; e-mail:
[email protected] (G. Gargiulo). Received 26 September 2011; received in revised form 14 December 2011; accepted 27 December 2011
Summary Pulmonary artery banding is a simple palliative surgical procedure for congenital heart defects with left-to-right shunt or complete mixing and pulmonary over-circulation. Even though indication for pulmonary artery banding has been sensibly reduced, since early reparative surgery has been proved superior to palliation and a staged approach, an increasing support for pulmonary banding has been raised in the last two decades by new indications such as left ventricular retraining, in the late arterial switch operation for complete transposition of the great arteries or before the double-switch operation in congenitally corrected transposition. Along with the increasing interest raised by the new indications and the consequently more diffuse use of banding, debanding has become an important surgical issue. Debanding is usually performed several months after palliation along with the repair of the cardiac malformations; otherwise, it can be done progressively or partially to further delay surgery and let the patient grow. Occasionally, after pulmonary artery banding, a spontaneous resolution of the underlying cardiac malformation can occur; however, a debanding procedure is in any case necessary. Keywords: Pulmonary artery debanding • Pulmonary over-circulation • Pulmonary banding
INTRODUCTION Since pulmonary artery banding was introduced in 1952 [1], it has been utilized for many different congenital heart lesions [2,3] to reduce pulmonary overflow and improve cardiac symptoms, preventing heart failure and pulmonary hypertension. Over the last 20 years, the use of pulmonary artery banding has been sensibly reduced, since early reparative surgery, when feasible, has been proved safer and more effective compared with a staged approach [4]. Nevertheless, pulmonary artery banding is nowadays still in common clinical use in selected cases such as: ‘functionally’ single-ventricle hearts with unrestricted pulmonary blood flow, multiple ventricular septal defects (VSDs), complex complete atrio-ventricular canal, complex coarctation, aortic arch obstruction with VSD, or when left ventricular retraining is needed in cases such as a late-referred transposition of the great arteries (TGA) [5] or congenitally corrected transposition of the great arteries (ccTGA) [6]. New indications for pulmonary artery banding have been considered in hypoplastic left heart syndrome along with ductus arteriosus stenting during a hybrid palliative procedure. A series of potential complications along with difficulties in determining the optimal tightness with the consequent risk of early or even multiple reoperations [7] make pulmonary artery banding a far from banal procedure that also carries a quite high mortality [8]. Each time a pulmonary artery band is positioned, a debanding procedure should always be expected at the time of cardiac malformation repair or when the underlying cardiac lesion has spontaneously resolved. Moreover, in selected cases, when waiting for the ideal time for complete correction is required, a partial and progressive debanding or band loosening can be indicated even
though the patient is exposed to an adjunctive open-chest procedure. The high rate of reoperations, along with the opportunity to adjust the band’s tightness and the need for removing the band and consequently reconstructing the pulmonary artery at the time of repair, have prompted surgeons to look for some alternative debanding techniques, such as reabsorbable material bands [9,10], catheter debanding systems [11] or telemetric adjustable devices [12], with the aim of reducing the number of open-chest procedures.
SURGICAL TECHNIQUE Pulmonary artery banding is a simple palliative technique to counteract pulmonary over-circulation in some congenital heart diseases. Usually, a 3–4 mm wide band is positioned around the main pulmonary artery to reduce its cross-sectional area opposing an increased resistance to the right ventricular outflow and therefore reducing left-to-right shunt or reducing pulmonary flow and increasing systemic flow in ‘single-ventricle’ hearts. The debanding techniques proposed are multiple, depending on the underlying heart malformation, the time expected for the next surgical step, the prospect of spontaneous resolution of the malformation and the need to repeatedly adjust the band‘s tightness. (i) In the case of classic open-chest debanding, a 4-mm Dacron band is positioned and secured and progressively tightened with stitches or with metallic clips at the time of the pulmonary banding procedure. At the time of repair, after starting the cardiopulmonary bypass, the band around the pulmonary artery is identified, starting from the metallic
© The Author 2012. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
G. Oppido et al. / Multimedia Manual of Cardio-Thoracic Surgery
Video 1: At the time of repair, after starting the cardiopulmonary bypass, the band around the pulmonary artery is identified starting from the metallic clip and dissected free. The pulmonary artery wall is extremely thin and fragile underneath the band and should be handled carefully. The band is divided and removed.
clip, and dissected free. The pulmonary artery wall is extremely thin and fragile underneath the band and should be handled carefully. The band is divided and removed (Video 1). (ii) Band removal may lead to stenosis of the main pulmonary artery, which may or may not require surgical treatment. Routinely, an appropriately size probe is passed through the tricuspid valve and the right ventricular outflow tract into the main pulmonary artery to evaluate the degree of narrowing. The main pulmonary artery is longitudinally incised through the narrowing; the ostia of the pulmonary branches are measured with the probe. In the case of stenosis, the main pulmonary artery is generously enlarged with a bovine pericardial patch. In particular cases, the main pulmonary trunk stenosis can be repaired with the excision of the narrowed area and performing an end-to-end anastomosis after adequate mobilization of the proximal and distal parts of the pulmonary artery. (iii) The result is again evaluated with the appropriately sized probe (Video 2). (iv) In cases requiring progressive loosening of the band or partial debanding, the band is secured beforehand with multiple metallic clips. At the time of the partial debanding or band loosening, the open-chest procedure can be avoided and the band is loosened by inflating a balloon catheter until the desired gradient is achieved (Video 3). (v) In the case of a muscular single or multiple VSD, when there is a high chance of spontaneous VSD closure, a reabsorbable band has been proposed and utilized with the aim of avoiding surgery just to remove the band. (vi) In cases where repeated band adjustments are expected, a Flow Watch device can be indicated, with the aim of avoiding multiple surgical reoperations; nevertheless, a final open-chest procedure to remove the device cannot be avoided.
DISCUSSION Pulmonary artery banding is a palliative procedure that can be extremely valuable in ameliorating clinical status and improving symptoms, preventing heart failure and pulmonary hypertension.
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Video 2: Band removal usually leads to stenosis of the main pulmonary artery, which may or may not require surgical treatment. An appropriately sized probe is passed through the tricuspid valve and the right ventricular outflow tract into the main pulmonary artery to evaluate the degree of narrowing. The main pulmonary artery is longitudinally incised through the narrowing; the ostia of the pulmonary branches are measured with a properly sized probe. The main pulmonary artery is generously enlarged with a bovine pericardial patch, and the result is evaluated with an appropriately sized probe.
Video 3: In this case, the pulmonary band was progressively tightened with clips and a partial debanding could be done by a catheter balloon dilatation.
Nevertheless, pulmonary banding can produce secondary changes, such as ventricular hypertrophy, pulmonary artery stenosis, pulmonary valve distortion, that can be detrimental and unfavourable. Therefore, a crucial point is to maintain a bandage in place no longer than is really necessary. After pulmonary artery banding, three different surgical scenarios can occur: (i) progressive loosening of the band to let the patient grow and waiting for the ideal time to safely repair the heart defect or proceed with the second-stage palliation; (ii) removing the band in case of the complete spontaneous resolution of the cardiac lesions; (iii) performing the definitive correction, thus removing the band and possibly enlarging the main pulmonary artery. Such situations have pushed surgeons to look for some alternative banding techniques in order to have a more easy debanding system and possibly reduce the rate of reoperations.
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G. Oppido et al. / Multimedia Manual of Cardio-Thoracic Surgery
The following are the more convincing alternatives utilized: (i) telemetric adjustable device (Flow Watch); (ii) reabsorbable material bands; (iii) catheter-based PAB loosening or debanding techniques. When repeated adjustments of the band’s tightness are expected to be required during the weeks and months following the operation, the use of a Flow Watch system can be appropriate. A Flow Watch is an implantable and telemetrically adjustable device proposed by Corno et al. [10] that can be both tightened or loosened as many times as needed over the long term according to necessity and it has been used with good results in several patients. Nevertheless, despite the obvious advantage of avoiding repeated operations, important drawbacks are represented by the very high cost of the device and by its large size, which makes it unsuitable for smaller patients. When a telemetric adjustable device is implanted, reoperation for device removal at the time of complete debanding is unfortunately necessary, even when a spontaneous resolution of the heart defect has occurred or even when pulmonary plasty is not required. To avoid surgery, some authors have suggested the use of a catheter-based procedure to perform progressive partial debanding to gain time for definitive repair or complete debanding in the case of spontaneous resolution of the heart defect. One of those less expensive percutaneous adjustable techniques has been proposed by Holmstrom et al. [11], who published a large series of patients who received a conventional band with a modification: interrupted extra mattresses are inserted along the free ends of the band with 3 mm interspaces. Surgery could be postponed for a median time of 9 months due to stepwise balloon dilatation, or a complete debanding by catheter was achieved and thus intervention could replace surgery in at least 47% of the cases. Another catheter-based technique to safely increase the pulmonary artery band diameter without surgery has been recently proposed by El-Said et al. [13]. The band is secured and progressively tightened with metallic clips positioned a few millimetres apart from each other; the inner clip can be slipped with the inflation of a balloon until it reaches the desired diameter. This technique could be repeated more than once during the patient’s growth and it proved effective also in completely removing the band and enlarging the main pulmonary artery. Exclusively in those cases when a spontaneous resolution of the heart defect is predictable, such as single or multiple muscular VSDs, the use of a bioabsorbable band can be an optimal solution as has been described by different authors [14,15]. Even though a complete surgery or catheter-free debanding can occur, the band’s reabsorption time can be variable and somehow unpredictable and, theoretically, if too fast, can result in the need for surgery. In transpositions, either complete or congenitally corrected pulmonary artery banding, performed in the attempt of retraining the left ventricle, one may take advantage of a progressive tightening because an acute pressure overload may not be tolerated unless progressive and gradual or it may require a progressive loosening with patient growth to gain time if performed in ccTGA very early in life. In both situations, the ideal timing of the debanding and definitive surgery is under debate, and different suggestions have been made by different authors [16–19].
CONCLUSIONS Pulmonary artery banding is technically a simple palliative operation that can be very complex from the overall management point of view; difficulties in optimizing the size, various potential early and late complications and the choice of the ideal time of debanding and definitive repair can make this simple operation a challenge for surgeons. Debanding is a crucial issue for many reasons: (i) the optimal time when a complete repair or a second-step palliation is considered can be subjective and an uncertain variable; (ii) a partial debanding, or band loosening, can be preferred in some cases to gain time and let the patient grow for definitive surgery or second-step palliation; (iii) it can be a cumbersome procedure when a spontaneous resolution of the underlying heart disease has occurred; (iv) it could also require pulmonary artery patch reconstruction. Some alternative techniques to overcome those problems and the need for repeated open-chest surgeries have been shown to be promising. Conflict of interest: none declared.
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