Ann Thorac Surg 2007;84:1617-1618. doi:10.1016/j.athoracsur.2007.07.096
© 2007 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Invited commentary
Shunji Sano, MD, PhD
Department of Cardiovascular Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama 700-8558, Japan
(Email: s_sano{at}cc.okayama-u.ac.jp).
The right ventricle-pulmonary artery (RV-PA) shunt was first introduced by Norwood and colleagues [1] in 1981 as a first-stage palliation of hypoplastic left heart syndrome (HLHS) and was abandoned until 1998 when we started using this technique with the modification of a small nonvalved polytetrafluoroethylene (PTFE) graft [2]. Since then, many centers have adopted stage I palliation with an RV-PA shunt and reported significant improvement in stage I mortality and morbidity. In some centers, mortality in stage I palliation has dropped below 10% [3]. However, controversies still remain regarding the systemic-to-pulmonary shunt versus the RV-PA shunt on the long-term results of HLHS [4].
In this article, Januszewska and colleagues [5] report their experience with the fenestrated Fontan operation (lateral tunnel technique) in 50 patients: Group 1 (n = 19) after the modified Blalock-Taussig shunt (Impra Inc, Tempe, AZ), and Group 2 (n = 31) after the right ventricle-pulmonary artery shunt during the Norwood procedure between 1995 and 2006. Fifty survivors underwent a fenestrated Fontan operation using a lateral tunnel technique. The authors compared demographic, echocardiographic, hemodynamic data, complications, and mortality between the two groups. They concluded that the Norwood procedure with the RV-PA shunt provides satisfactory late hemodynamics and produces good candidates for the Fontan operation. However, they warned that patients with a RV-PA shunt have a higher incidence of systemic-to-pulmonary arterial collaterals.
We all know that systemic-to-pulmonary arterial collaterals develop in patients with a single ventricle who have a long interval between bidirectional Glenn/hemi-Fontan (stage II) and Fontan (stage III) operations and in patients with long-standing moderate to severe cyanosis. The authors [5] report the age at stage III (Fontan) was 21.7 months in group 1 and 29.1 months in group 2, and the age at angiogram was 23.2 months in group 1 and 28.0 months in group 2. The interval between stage II and stage III operations was 15.2 months in group 1 and 22.7 months in group 2. It is therefore difficult to draw a conclusion that systemic-to-pulmonary arterial collaterals are more prone to develop in patients with RV-PA shunts.
Furthermore, the authors used 5-mm PTFE grafts for RV-PA shunts in patients with a mean body weight of 3.4 kg [5]. The mean body weight of our patients was 2.8 kg, and we recommended a 6-mm PTFE grafts for patients weighing more than 3.5 kg. Therefore, hypoxemia seems to be due to a small shunt rather than the type of shunt. We also reported that the RV-PA shunt was left open at the time of stage II palliation to keep systemic oxygen saturation higher if the patients do not have tricuspid regurgitation. Of note, we observed systemic-to-pulmonary arterial collaterals in a few patients, but these were not significant collaterals.
The effects of a right ventriculotomy for placement of the RV-PA shunt on systemic RV function are of great concern. The necessity for a right ventriculotomy, which may affect contractile function of the systemic ventricle, is a potential disadvantage of the RV-PA shunt. As the authors mentioned [5], hemodynamic parameters obtained from cardiac catheterization were similar in these two groups. Evaluation of RV function is difficult, and we need to assess global and regional RV function.
The authors mentioned that the right ventriculotomy was not a substrate for ventricular arrhythmias. Many articles report no adverse effect on RV function and no significant arrhythmia after an RV-PA shunt; however, long-term follow-up is necessary. Clearly, a more extensive experience is necessary before a definitive conclusion can be drawn.
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References
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- Norwood WI, Lang P, Castaneda AR, Campbell DN. Experience with operations for hypoplastic left heart syndrome J Thorac Cardiovasc Surg 1981;82:511-519.[Abstract]
- Sano S, Ishino K, Kawada M, et al. Right ventricle-to-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome J Thorac Cardiovasc Surg 2003;126:504-510.[Abstract/Free Full Text]
- Sano S, Ishino K, Kawada M, Honjyo O. Right ventricle-to-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]
- Tabbutt S, Dominguez TE, Ravishankar C, et al. Outcomes after the stage I reconstruction comparing the right ventricular to pulmonary artery conduit with the modified Blalock Taussig shunt Ann Thorac Surg 2005;80:1582-1591.[Abstract/Free Full Text]
- Januszewska K, Mroczek T, Stebel A, Malec E, et al. Consequences of right ventricle-to-pulmonary artery shunt at the first stage for the Fontan operation Ann Thorac Surg 2007;84:1611-1618.[Abstract/Free Full Text]
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