J Thorac Cardiovasc Surg 2005;130:1720-1722
© 2005 The American Association for Thoracic Surgery
A modified elephant trunk technique: The 3-fold elephant trunk technique
Kenji Okada, MD
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,
Taijiro Sueda, MD,
Kazumasa Orihashi, MD,
Katsuhiko Imai, MD,
Katsutoshi Sato, MD
Department of Cardiovascular Surgery, Hiroshima University Hospital, Hiroshima, Japan
* Address for reprints: Kenji Okada, MD, Department of Cardiovascular Surgery, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan (Email: kokada{at}hiroshima-u.ac.jp).
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Okada
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We report a modified elephant trunk (ET) technique, the 3-fold ET technique. This technique is an alternative for preventing thromboembolic events and paraplegia.
Technical Description
The reversed and bidirectional ET
1
is made by invaginating the prosthesis. The idea for this modified technique arose from enveloping the prosthesis instead of invaginating it. A single and straight prosthesis is folded twice and made into a 3-fold ET (Figure 1). The first fold is placed about 7 cm from the end. The second fold is made backward, 5 cm back to the proximal site. In other words, the distance between the proximal edge and the second fold is about 2 cm. Two stitches are placed on each of the proximal and distal sides to fix the ET in place. The stitches are put in to prevent the invasion of blood flow into the fold. The ET is about 7 cm in length folded and 17 cm in length unfolded.
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Figure 1. Schema of the 3-fold elephant trunk technique. The 3-fold elephant trunk consists of 2 parts: one 2-cm single tube and another 5-cm triple tube. A, Straight graft; B, folded graft; C, 3-fold graft (2-cm single tube and 5-cm triple tube) with 4 stitches.
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During the first operation, the prefabricated prosthesis is inserted into the distal aneurysm while the ascending aorta and aortic arch are repaired. During the second operation, a clamp is put on a 2-cm single tube at the proximal side, and then the aneurysm is opened. At the proximal site, the ET is located within the lumen. The 4 stitches are pulled away, and the ET is pulled out. Then the prosthesis is pulled open. The triple prosthesis with 2 folds is stretched as an unfolded, straight, and single graft. Then the residual aneurysm is opened, and a proximal anastomosis is made between the 3-fold ET and the new prosthesis.
Discussion
The formation of blood clots in the blind pocket between the trunk and the native aneurysmal wall could give rise to thromboembolic events, a long ET could result in thrombotic occlusion of some critical intercostal arteries, or paraplegia could arise. Heinemann and colleagues
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have reported that some old clots are often found in blind aortic pockets surrounding the trunk. The longer the trunk, the more stasis in the blind pocket.
The prosthesis was 10 cm long in the original article.
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Schepens and associates
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have advocated using prostheses 5 to 10 cm long. In other words, to facilitate secondary operations, ETs should be longer. However, to prevent thromboembolic events and paraplegia, ETs should be as short as possible. There is an inconsistency between the 2 requirements. The 3-fold ET technique can address this inconsistency.
By using this technique, the prosthesis can be made to be less than 10 cm long. At subsequent operations, the folded prosthesis can be unfolded. Then a triple-length ET graft of up to 17 cm can be obtained immediately. Use of this type of graft reduces the frequency of thromboembolic events and paraplegia. In addition, the grafts are long enough to facilitate secondary operations.
The original article
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indicated that the ET graft was 10 cm long, and the free end floated freely within the lumen. There was some concern over mechanical complications, such as graft kinking, obstruction, or wrinkled and shrunken ET grafts. These complications could induce a significant pressure gradient within the ET graft. We modeled this problem and, as shown in Figure 2, the inside diameter is sufficient with a 3-fold ET. We also think that freely floating ETs can cause intimal injuries. Ideally, an ET graft should be a little rigid and sufficiently long. The modified technique meets both of these requirements.
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Figure 2. Photographs of the operation. A, An image showing the 3-fold elephant trunk technique. B, Significant stenosis is not seen in the lumen of 3-fold elephant trunk grafts.
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The formation of blood clots might be a matter of concern with ET grafts. Carrel and coworkers
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have reported that no macroscopic clots were found between the 2 layers of the reversed and bidirectional ET graft. We hypothesize that the blood flow always touches the outside surface of the prosthesis because of the invaginating nature of the prosthesis. Essentially, a prosthesis should permit the passage of blood from the inside. There are many special anticoagulant artifices on the inside surface of the prosthesis. On the contrary, there are no anticoagulant mechanisms on the outside surface of the prosthesis. We concluded that to prevent clot formation, it was most important to force blood to flow continuously along the inside surface of the graft. Therefore the concept of the 3-fold ET favors an enveloping prosthesis and not an invaginating prosthesis.
References
- Carrel T, Berdat P, Kipfer B, Eckstein F, Schmidli J. The reversed and bidirectional elephant trunk technique in the treatment of complex aortic aneurysms. J Thorac Cardiovasc Surg 2001;122:587-591.[Abstract/Free Full Text]
- Heinemann MK, Buehner B, Jurmann MJ, Borst HG. Use of the "elephant trunk technique" in aortic surgery. Ann Thorac Surg 1995;60:2-7.[Abstract/Free Full Text]
- Borst HG, Walterbusch G, Schaps D. Extensive aortic replacement using "elephant trunk" prosthesis. Thorac Cardiovasc Surg 1983;31:37-40.[Medline]
- Schepens MA, Dossche KM, Morshuis WJ, van den Barselaar PJ, Heijmen RH, Vermeulen FE. The elephant trunk technique: operative results in 100 consecutive patients. Eur J Cardiothorac Surg 2002;21:276-281.[Abstract/Free Full Text]
