Ann Thorac Surg 2006;81:1148-1149
© 2006 The Society of Thoracic Surgeons
How to do it
Simple Technique to Quickly Access a RV-PA Shunt During the Second Stage of the Norwood-Fontan Pathway
Hitendu Dave, MD
*
,
René Prêtre, MD
Paediatric Cardiac Surgery, University Childrens Hospital, Zurich, Switzerland
Accepted for publication December 28, 2004.
* Address correspondence to Dr Dave, Division of Paediatric Cardiac Surgery, University Childrens Hospital (Kinderspital Zurich), Steinwiesstrasse 75, Zurich, CH-8032 Switzerland (Email: hitendu.dave{at}kispi.unizh.ch).
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Abstract
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We describe a simple technique of wrapping the right ventricle to pulmonary artery shunt with a PTFE (polytetrafluoroethylene) band during the first stage of the Norwood procedure, which helps quick and safe access to the shunt during the subsequent stage of the Fontan pathway.
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Introduction
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The Norwood operation involving the enlargement of the hypoplastic aortic arch, resection of the atrial septum, setting the pulmonary valve in the systemic circulation, and a systemic to pulmonary artery shunt has been the preferred modality of treating the hypoplastic left heart syndrome. This is followed by take down of the systemic to pulmonary artery shunt and construction of a bidirectional cavopulmonary anastomosis during the second stage, and a total cavopulmonary connection during the third stage. Recently, the classic systemic artery to pulmonary artery shunt has been increasingly replaced by a right ventricle to pulmonary artery (RV-PA) shunt, mainly due to its inherent advantage of allowing better coronary perfusion by maintaining higher diastolic pressures in the aorta and improving the pulmonary to systemic flow quotient [1–4].
The Norwood II procedure is routinely performed between 2 to 4 months after the primary procedure, when the cardiac landmarks are difficult to identify due to postoperative adhesions. The cavopulmonary anastomosis lies on the right side of the heart and requires minimal dissection. On the other hand, the RV-PA shunt lies far away on the left side of the heart and the neo-ascending aorta. It can be difficult to isolate the RV-PA shunt, and the dissection carries a potential risk of creating an iatrogenic lesion.
In our more recent cases of the Norwood procedure, we have used a simple technique to allow rapid and safe access to the RV-PA shunt.
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Technique
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During the first stage of the Norwood procedure, after completion of the RV-PA shunt usually with a 5 mm Impra graft (ePTFE thinwall vascular graft, BARD [Peripheral Vascular] Inc, Tempe, AZ), a 4 mm PTFE braided tape (Impra Inc, Tempe, AZ) was wrapped around the shunt approximately midway between the anastomoses. Care was taken that the band sat uniformly around the shunt; the two ends were grasped together and pulled up, and a medium sized clip was applied snugly adjacent to the shunt without producing any constriction [5]. Both the apposed arms of the band were laid gently curving in front of the ascending aorta to its right side, held together with a clip and cut (Figs 1, 2). 
No fixation stitches were used to fix the band onto the Goretex shunt. Because all of the patients undergoing the Norwood I operation undergo a delayed sternal closure in our unit, a 0.4-mm ePTFE Gore "Preclude" pericardial membrane (W. L. Gore & Associates Inc, Flagstaff, AZ) is used to bridge the retracted pericardial margins.
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Fig 1. Schematic diagram shows completed Norwood I type repair with a 4 mm PTFE braided tape wrapped around the right ventricle to pulmonary artery shunt as a guidance during reoperation. Inset diagram in the right upper hand corner demonstrates the ease with which the shunt could be reached during the subsequent operation.
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During the second stage of the operation, once the pericardial membrane was removed, the cut ends of the PTFE band were easily identified, unclipped, and spread apart (see inset, Fig 1), thus easily leading to the shunt with minimal dissection of the surrounding fibrotic tissue. Once cardiopulmonary bypass was established, the shunt was clamped, cut, and both ends were oversewn.
We used this technique in 10 recent consecutive Norwood I operations. The band was easily found at reoperation in 8 patients (2 are awaiting the second stage).
Dissection of the RV-PA shunt was extremely quick without causing any injury to the myocardium, aorta or the pulmonary artery. In 1 patient, the shunt was dissected down to the pulmonary artery and an autologous pericardial patch plasty was added. Proximally, the divided shunt was sewn distal to the cross-clamp using running polypropylene stitches. Additional U-stitches were used in 3 patients to obliterate any stump where stagnation of blood could have occurred. The whole procedure (including the bidirectional Glenn anastomosis) was performed without cross clamping the aorta.
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Comment
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The major change in the management of the Norwood-Fontan pathway that has been recently proposed is the application of an RV-PA shunt instead of a central systemico-pulmonary shunt [1–4]. The increased diastolic pressure and hemodynamic stability obtained with this shunt has convinced many surgeons to switch their technique to the modification. However, with this modification, the second stage (ie, the cavopulmonary anastomosis operation) is more difficult to perform, in part due to the removal of the shunt located on the left side of the heart. During the first stage of the Norwood procedure, it is almost mandatory that the pericardial gap be bridged with some sort of a membrane to provide protection during subsequent re-sternotomies. Irrespective of the type of membrane used for the pericardial sac closure, the opacified epicardium that one encounters in a reoperation (commonly experienced by us while using a Gore pericardial membrane), masks the distinction between the myocardium and the RV-PA shunt and everything looks frozen. Although we did not encounter any serious iatrogenic injuries during dissection when we did not routinely use the band, it is not unusual to enter a wrong plane of dissection when the adhesions are severe. Furthermore, in some patients, the RV-PA graft lies extremely laterally on the left side and can be troublesome to access. Our technique of placing a guiding band around the shunt has proved to be very advantageous during the second stage operation. The guiding band lying to the right of the neoaorta is easy to find and allows access to the RV-PA shunt with minimal dissection. By simply spreading apart both arms of the band, it is possible to isolate, interrupt, and obliterate the stumps at either end of the shunt, thus eliminating a potential source of thromboembolism. To conclude, we consider this simple technique a harmless surgical adjunct to simplify the subsequent surgical procedure.
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References
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- Malec E, Januszewska K, Kolcz J, Mroczek T. Right ventricle-to-pulmonary artery shunt versus modified Blalock-Taussig shunt in the Norwood procedure for hypoplastic left heart syndromeinfluence on early and late haemodynamic status. Eur J Cardiothorac Surg 2003;23(5):728-733discussion 733–4.[Abstract/Free Full Text]
- Pizarro C, Malec E, Maher KO, et al. Right ventricle to pulmonary artery conduit improves outcome after stage I Norwood for hypoplastic left heart syndrome Circulation 2003;108(Suppl 1):II155-II160.
- Azakie A, Martinez D, Sapru A, Fineman J, Teitel D, Karl TR. Impact of right ventricle to pulmonary artery conduit on outcome of the modified Norwood procedure Ann Thorac Surg 2004;77(5):1727-1733.[Abstract/Free Full Text]
- Sano S, Ishino K, Kawada M, Honjo O. Right ventricle-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2004;7:22-31.[Medline]
- Mahle WT, Cuadrado AR, Tam VK. Early experience with a modified Norwood procedure using right ventricle to pulmonary artery conduit Ann Thorac Surg 2003;76:1084-1088discussion 10895 Prêtre R, Benedikt P, Turina MI. Precise adjustment of a band on the main pulmonary artery Thorac Cardiovasc Surg 2000;48(1):45.[Medline]
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Abstract
Introduction
