Eur J Cardiothorac Surg 2006;29:253-254
© 2006 Elsevier Science NL
Adjustable aorto-pulmonary shunt to prevent temporary pulmonary over-circulation
Carlo Pace Napoleone
*
,
Guido Oppido,
Emanuela Angeli,
Gaetano Gargiulo
Pediatric Cardiac Surgery Unit, S.Orsola-Malpighi Hospital, Bologna Medical School, Via Massarenti 9, 40138 Bologna, Italy
Received 26 August 2005;
received in revised form 7 November 2005;
accepted 15 November 2005.
* Corresponding author. Tel.: +39 051 6363156; fax: +39 051 6363157. (Email: pax{at}med.unibo.it).
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Abstract
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The Blalock–Taussig shunt can produce a temporary pulmonary over-circulation and can be downsized with a metallic clip. This hemodynamic situation can be reversible leading to desaturation.
We describe a very simple method to resize temporarily the shunt with a removable metallic clip.
Key Words: Hypoplastic left heart syndrome • Shunt anastomosis • Surgical • Pulmonary circulation
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1. Introduction
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The immediate post-operative course after surgery for a single ventricle with shunt-dependent pulmonary circulation can be significantly influenced by a well-balanced pulmonary and systemic flow. This balance can be manipulated modifying the systemic or pulmonary resistances with inhalatory gases or pharmacologic support. Moreover, in case of pulmonary over-circulation, a simple method of downsizing the shunt with a metallic clip has been described [1].
Usually, in the immediate post-extra corporeal circulation period, the most critical problems can derive from a pulmonary overflow causing a low cardiac output. In these cases it is possible to reach a clinical stabilization reducing the pulmonary flow with various methods. This hemodynamic condition can be easily and rapidly reversible. The simple method of shunt size reduction with a metallic clip can help in this situation, but leave a reduced shunt flow also when the life-threatening hemodynamic situation is overcome.
So it can be useful to obtain a reversible reduction of the shunt size, in order to help the patient to survive to some special events, like the sternotomy closure or a period of low cardiac output, with the possibility of restoring an adequate pulmonary flow if the improvement of the hemodynamic condition allows the clip removal.
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2. Technique description
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This technique is just an update of that described by Kuduvalli et al. [1]. The only difference is that, before placing the haemostatic clip (Ligaclip Small, Ethicon Inc., Somerville, NJ, USA), a 5/0 Prolene (Ethicon Inc.) is passed inside it so as to remain anchored to the placed clip (Fig. 1
). This stitch is then passed across the sternotomy wound at the level of the jugulum. The clip must be smoothly placed and we start with an approximate size reduction of 1/3 of the original, trying to obtain, with a 50% O2 fraction ventilation, an oxygen saturation not inferior to 70% with a significant increase of the diastolic systemic pressure (Fig. 2
). A reliable management of the hemodynamic condition may be achieved, thus enabling a safe and possibly definitive sternal closure. A continuous heparin infusion will be necessary to maintain the ACT between 170 and 200 sec. If a stable hemodynamic condition is obtained during the following days and a persistent desaturation demands an increase in pulmonary flow, the clip can be easily removed with a gentle traction on the 5/0 stitch. This operation will restore the initial size of the shunt. Should the removal of the clip not be necessary, the Prolene stitch can be cut at the level of the skin leaving it down in the sternotomy wound.
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3. Results
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The described technique was used in six cases: one was suffering from pulmonary atresia with intact ventricular septum (PA-IVS), four were classic Norwood stage I procedure while one was a tricuspid atresia. In all cases a PTFE shunt was interposed between the right brachiocephalic trunk and the pulmonary artery. In the first five cases (PA-IVS and Norwood stage I procedure), the closure of the sternum was possible after downsizing the shunt. The clips were then removed after a mean period of 2 days, when a stabilization of the patient was reached. The last patient received a modified Blalock–Taussig shunt. He developed a pneumonia that was treated with ECMO and shunt closure with a removable clip. When the chest X-ray normalized, the clip was removed and the weaning from ECMO was possible in 2 days time. In this case, the removable clip help us to understand if the pulmonary parenchyma was suitable to ventilate the patient so as to switch off the ECMO without reopening the sternotomy to remove the clip.
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4. Discussion
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The problem of pulmonary temporary over-circulation was recognized by Chikada et al. [2] who proposed a banding of the brachiocephalic trunk that can be dilated in a subsequent time.
Schmid et al. [3] described an adjustable tourniquet placed around the shunt, left in situ beneath the linea alba; in small neonates it can lead to problems.
Kuduvalli et al. [1] reached the right solution but they had to face another dilemma: if the sternum was closed, it was not possible to remove the clip without reopening it.
We overcame this problem because the hemodynamic improvement obtained with the reduction of shunt size will increase the possibility to close the sternum, and, after obtaining the required stability, it is possible to remove the clip with consequent saturation improvement.
Noteworthy, we have not seen any thrombogenic complication and in all cases, after removing the metallic clip, the echocardiographic appearance of the shunt was very regular, without images referring to intravascular thrombi. No hemorrhagic problems related with clip removal were encountered during our experience.
In conclusion, we describe a very simple technique of temporary shunt downsizing that can be helpful in some specific situation. The possibility to remove the clip led also to a more liberal use of this technique.
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References
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- Kuduvalli M, McLaughlin KE, Trivedi DB, Pozzi M. Norwood-type operation with adjustable systemic–pulmonary shunt using hemostatic clip. Ann Thorac Surg 2001;72:634-635.[Abstract/Free Full Text]
- Chikada M, Sekiguchi A, Oho S, Miyamoto T, Ishida R, Takayama H, Ishizawa A. Dilatable banding of a Blalock–Taussig shunt. Ann Thorac Surg 2002;74:253-255.[Abstract/Free Full Text]
- Schmid FX, Kampmann C, Kuroczynski W, Choi YH, Knuf M, Tzanova I, Oelert H. Adjustable tourniquet to manipulate pulmonary blood flow after Norwood operations. Ann Thorac Surg 1999;68:2306-2309.[Abstract/Free Full Text]
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Abstract
1. Introduction
