Ann Thorac Surg 2009;88:974-978. doi:10.1016/j.athoracsur.2009.03.014
© 2009 The Society of Thoracic Surgeons
New Technology
3-Dimensional Printing of Models to Create Custom-Made Devices for Coil Embolization of an Anastomotic Leak After Aortic Arch Replacement
Ralf Sodian, MDa,*,
Daniel Schmauss, MSa,
Christoph Schmitz, MDa,
Amir Bigdeli, MDa,
Sandra Haeberle, MSa,
Michael Schmoeckel, MDa,
Matthias Markert, MSb,
Tim Lueth, PhDb,
Franz Freudenthal, MDc,
Bruno Reichart, MDa,
Rainer Kozlik-Feldmann, MDc
a Department of Cardiac Surgery, Ludwig-Maximilians-University, Munich, Germany
b Institute of Micro Technology and Medical Device Technology, Technical University Munich, Garching, Germany
c Department of Pediatric Cardiology, Ludwig-Maximilians-University, Munich, Germany
Accepted for publication March 9, 2009.
* Address correspondence to Dr Sodian, Department of Cardiac Surgery, Ludwig-Maximilians-University, Marchioninistr. 15, Munich, 81377, Germany (Email: ralf.sodian{at}med.uni-muenchen.de).
 |
Abstract
|
|---|
Purpose: The objective of this study was to show the use of 3-dimensional printing models to fabricate a custom-made occluder for device embolization of an anastomotic leak after replacement of the ascending aorta and the aortic arch in a human immunodeficiency virus (HIV)-infected patient.
Description: We present a 50-year-old HIV-infected patient who underwent ascending aorta and aortic arch replacement for a type A dissection, and who had an aortic arch pseudoaneurysm (sized 5 x 5 x 4 cm) with a slit-shaped entrance hole located anteriorly to the implanted supra-aortic vessels. The patient's 128-slice computed tomography data were visualized and reconstructed. Afterward we fabricated a life-like replica of the complex pathology of the ascending aorta and the aortic arch using a rapid prototyping machine. After careful examination of the model, we fabricated a custom-made occluder device for interventional closure of the leakage.
Evaluation: Using data derived from 128-slid computed tomography linked to proprietary software, we were able to create models of the ascending aorta, the aortic arch end, especially the pseudoaneurysm with its slit-shaped opening between the aortic lumen and the aneurysm. This was very helpful to build a perfectly fitting custom-made occluder device to plan and simulate the interventional closure. Moreover, the models were helpful for intra-interventional orientation.
Conclusions: The stereolithographic replicas were extremely useful for choosing the treatment option and for planning and simulating the occlusion of the pseudoaneurysm. Furthermore, the models were necessary for our engineers who were building the custom-made occluder device.
|
Introduction
|
|---|
Development of an aortic graft pseudoaneurysm after replacement of the ascending aorta and the aortic arch with reimplantation of the supra-aortic arteries is a severe complication after surgery [1].
Therapeutic options in asymptomatic and symptomatic patients include resection of the pseudoaneurysm or endovascular stenting [2]. Making a decision is often difficult in these patients due to a missing possibility to exactly estimate the dimensions of the aneurysm, its relationship to the supra-aortic arteries, and the shape of the opening between the aneurysm and the aortic lumen.
Therefore, it might be important to establish high-quality preoperative data for optimal surgical or interventional planning to minimize morbidity and mortality. Actually, we developed a new technique to fabricate a life-like model of the exact anatomic structures of patients with a pseudoaneurysm after previous aortic replacement using rapid prototyping techniques [3].
Rapid prototyping is a new technology used in engineering and industry to generate prototype models. Transferring this method to cardiovascular surgery enables to fabricate three-dimensional replicas of complex anatomic structures from computed tomography (CT) or magnetic resonance imaging data of patients. We previously described the use of 3-dimensional models for surgical planning and intraoperative orientation for pediatric and adult patients with complex cardiovascular anatomy [4].
Hereby we present a new approach to use stereolithographic models derived from standard CT to create life-like models of the exact anatomy of the aortic arch and the supra-aortic vessels for therapeutical decision-making, pre-intraventional planning, and intra-interventional orientation. As a proof of concept, we present a 50-year-old HIV-infected male patient who had undergone ascending aorta and aortic arch replacement for a type A dissection 6 months ago, and an aortic arch pseudoaneurysm that developed. In this situation, solid replicas are helpful for therapeutical decision-making, the fabrication of a perfectly fitting custom-made occluder device, and pre-interventional and intra-interventional orientation.
|
Technology
|
|---|
We demonstrate an HIV-infected patient with an aortic arch graft pseudoaneurysm after ascending aortic and arch replacement due to an acute type A dissection 6 months ago. The pseudoaneurysm was diagnosed through a CT scan that showed the formation of a frontolateral aneurysm and a slit-shaped opening between the aneurysm and the aortic lumen (sized 3.8 x 1 cm). The patient is extraordinary tall (205 cm or 6 feet, 8 inches) but was not diagnosed with Marfan syndrome. The CT scan revealed contact of the pseudoaneurysm with the innominate vein, the sternum, and the supra-aortic vessels (Fig 1).
Nevertheless, the patient was asymptomatic. As indicated by the diagnostic findings and an increased risk of rupture of the aneurysm or dissection of the supra-aortic vessels, the patient required treatment. This included the options of surgical removal of the pseudoaneurysm and reimplantation of the supra-aortic vessels or percutaneous closure of the slit and coiling of the aneurysm using an occluder device.
|
Technique
|
|---|
There were strong pros and contras for each of the two options. Finally we decided to fabricate a 3-dimensional model to facilitate the decision-making process and see if an interventional closure might be feasible in this complex case or not. This therapeutic option was approved by the institutional ethics committee of the Ludwig-Maximilians University Munich.
The 128-slice CT data of our patient were delivered by disk to the Technical University Munich, Department of Micro Technology and Medical Device Technology, where they were re-programmed to produce a file that is readable by the stereolithography machine (STL format). These data (ie, 0.1-mm to 2-mm slices) were entered into the stereolithography machine (ZCorp, Burlington, MA), and a replica of the ascending aorta, the aortic arch, and the supra-aortic vessels was created, as previously reported [3, 4] (Fig 2A).
View larger version (69K):
[in this window]
[in a new window]
|
Fig 2. (A) Stereolithographic model of the aortic arch (outside view) and the aneurysm. (B) Stereolithographic model of the aortic arch (inside view) and preoperative testing of the interventional procedure with the custom-made occluder device.
|
|
These newly created models allowed us to clearly identify the dimensions of the pseudoaneurysm and the exact localization and shape of the connecting opening between the aortic lumen and the false aneurysm. The precise anatomic reason for designing the custom made device was the size of the aneurysm (4.5 x 4.3 x 2 cm), the slit-shaped opening, and the close relationship to the supra-aortic vessels, which made it impossible to use a commercially fabricated occluder device. Due to the slit shape of the opening and the close relationship to the supra-aortic vessels, an Amplatz-type device did not seem to be appropriate for the intervention. The Amplatz-type device is round shaped and would not completely occlude a long, slit-shaped opening. Moreover, the close relationship to the supra-aortic vessels made it impossible to position the device without occluding, one or even two supraaortic vessels. Similar to the Amplatzer device the custom made device is made of Nitinol. The occluder device is constructed in a single-wire technique. Due to its plasticity and flexible attachment to the transport system, it can easily adapt to the defect (Fig 2B). In the center of the device, a guidewire is fixed by a smaller wire to the device. Removing of the central wire releases the system. Three thin polyester membranes are attached inside of the occluder. A 10-French sheath was fabricated from tubing set. A short 12-French sheath covered the 10-French sheath at the end to have a hemostatic valve (FF and PFM, Cologne, Germany).
|
Clinical Experience
|
|---|
Based on the exact anatomic understanding and the discussion with our interventionalists and catheter engineers we determined an interventional closure of the pseudoaneurysm with a complete custom-made occluder device. The combination of an asymptomatic patient and a potentially high-risk surgical procedure made surgery only an alternative option if the interventional attempt would fail, especially in an HIV-infected patient.
Now we were able to simulate the intervention using the 3-dimensional models to anticipate difficulties during the intervention. Furthermore, the models were evaluated, measuring certain anatomical structures of the model, and compared to the data from our preoperative CT scan (Table 1). Moreover, the models were sterilized and taken to the catheter laboratory for better intra-interventional orientation. Here, the right femoral artery was punctured and cannulated with 10-French sheath. With a pigtail catheter several angiograms were performed to visualize the opening of the false aneurysm. The aneurysm was entered with a 6-French Judkins right coronary artery catheter and a j-shaped long wire was positioned inside the aneurysm. Now the 6-French Judkins catheter was exchanged against a 10-French long sheath, which was positioned at the distal end of the aneurysm. The device was mounted and pushed to the tip of the sheath and carefully positioned to the aneurysm from distal to proximal. A following control angiogram shows a nearly perfect position of the device inside the aneurysm and at the slit-shaped entrance of the false aneurysm. The post-interventional angiogram shows the occluder device inside of the false aneurysm and almost no perfusion (Fig 3). Only 3 months later, the follow-up CT scan (Fig 4) shows a completely thrombosed aneurysm without any evidence of contrast and the patient continued to live a normal life.
View larger version (120K):
[in this window]
[in a new window]
|
Fig 3. Post-interventional angiographic image showing the occluder device in the false aneurysm (see arrows).
|
|
View larger version (88K):
[in this window]
[in a new window]
|
Fig 4. Computed tomographic scan of the aortic arch 3 months after interventional closure of the anastomotic leak. Complete thrombosis of the pseudoaneurysm.
|
|
|
Comment
|
|---|
Rapid prototyping has been shown to be a useful tool in maxillofacial surgery, reconstructive surgery, neurosurgery, orthopedics, and in adult and pediatric cardiac surgery [5–7].
By using this technology, surgical templates or customized implants can be tested on the models, or anatomic structures can be reconstructed before the operation. These 3-dimensional, life-like models might also be helpful for perioperative planning of surgical or interventional procedures in a wide variety of clinical situations [8].
Surgical repair of aortic aneurysms and dissections may be associated with certain complications. Developing a false aneurysm after replacement of the ascending aorta and the aortic arch with reimplantation of the supra-aortic vessels is a rare but severe complication. The treatment of such leaks and pseudoaneurysms has mostly been surgical with a high rate of morbidity and mortality [1]. On the other hand, it is often complicated by repairing aneurysms, especially those located in the ascending aorta or the aortic arch, using endovascular interventional techniques [9]. The decision-making process is difficult and depends on the individual anatomy of the cardiovascular pathology and the constitution of each single patient. Unfortunately, it is often not easy to clearly identify the exact anatomic conditions, such as the shape, size, and exact location of the opening between the aortic lumen and the aneurysm.
To overcome these shortcomings, our group decided to apply rapid prototyping technology to fabricate models of the cardiovascular pathology. Our experiment with its use for interventional closure of an aortic arch pseudoaneurysm after previous replacement of the ascending aorta and the aortic arch demonstrates that with currently available CT technology, accurate 3-dimensional models of the anatomy of live patients can be fabricated. These models allow the surgeon or interventionalist to better understand patient-specific 3-dimensional anatomy. Moreover, being able to hold a model in one's hand and examine it from different sides allows the interventionalist and the surgeon to develop the optimal interventional approach and to anticipate difficulties that may arise. The dimensions and distances can be easily identified, and interventions or surgical procedures can be planned and simulated preoperatively. Furthermore, it is possible to fabricate perfectly fitting devices if required. All these are advantages compared with images created directly from the CT software. One difficulty of the technique is the selection of correct segmentation values. This requires a multidisciplinary approach with surgeons and computer specialists cooperating to achieve perfect segmentation that yields a perfect, anatomically correct model.
The procedure we performed is a proof of concept and shows that it is possible to fabricate stereolithographic models from a routine preoperative CT scan for patients with a false aneurysm after previous replacement of the ascending aorta and the aortic arch. However, as with other aneurysms, it is important to know that there is a risk of life-threatening complications, such as rupture, fistula formation, and compression of adjacent organs. In our patient, the aneurysm is completely thrombosed and there is no more perfusion or high pressure inside the false aneurysm after interventional closure. Therefore, we believe that the risk of rupture is significantly minimized, and we believe that the preoperative planning and interventional procedure was an attractive option for such a high-risk patient.
It allows for optimal custom-made device fabrication, and thus very precise positioning of a transcatheter-delivered occluder device. The patient recovered very well from this procedure and could be discharged home after 4 days. We believe that this approach was a good therapeutic option for this special HIV-infected patient. Despite advances in interventional techniques, treatment in the majority of cases remains surgical. The surgical procedure might be complex and has a high mortality. Mohammadi and colleagues [1] describe an operative mortality of 17.2%, and rupture of the false aneurysm during re-sternotomy of more than 30%. Therefore, we believe that these data justify a new and relatively straightforward interventional approach, especially in a patient with HIV.
In conclusion, the method described is feasible for patients with false aneurysm after previous replacement of the ascending aorta and the aortic arch. The system provides theoretic and practical advantages for interventionalists and surgeons treating complex pathology in cardiac interventionalism and surgery. Future studies that include more patients and provide more data are expected to show that the use of pre-interventional and preoperative models decreases perioperative morbidity and mortality.
|
Disclosures and Freedom of Investigation
|
|---|
The stereolithographic models were purchased by the Institute of Micro Technology and Medical Device Technology (Technical University Munich). The authors have performed a free and independent development and evaluation of this new technology. The authors have no financial relationship with companies producing stereolithographic models. The occlusion device was custom-made by PFM (Cologne, Germany).
|
Footnotes
|
|---|
Disclaimer The Society of Thoracic Surgeons, the Southern Thoracic Surgical Association, and The Annals of Thoracic Surgery neither endorse nor discourage use of the new technology described in this article.
|
References
|
|---|
- Mohammadi S, Bonnet N, Leprince P, et al. Reoperation for false aneurysm of the ascending aorta after its prosthetic replacement: surgical strategy Ann Thorac Surg 2005;79:147-152.[Abstract/Free Full Text]
- Cawley PJ, Gill E, Goldberg S. Successful percutaneous closure of an aortic graft pseudo-aneurysm with a patent foramen ovale occluder device J Invasive Cardiol 2008;20:E19-E22.[Medline]
- Sodian R, Weber S, Markert M, et al. Stereolitographic models for surgical planning in congenital heart surgery Ann Thorac Surg 2007;83:1854-1857.[Abstract/Free Full Text]
- Sodian R, Schmauss D, Markert M, et al. Three-dimensional printing creates models for surgical planning of aortic valve replacement after previous coronary bypass grafting Ann Thorac Surg 2008;85:2105-2108.[Abstract/Free Full Text]
- Winder J, Bibb R. Medical rapid prototyping technologies: state of the art and current limitations for application in oral and maxillofacial surgery J Oral Maxillofac Surg 2005;63:1006-1015.[Medline]
- Fukui N, Ueno T, Fukuda A, Nakamura K. The use of stereolithography for an unusual patellofemoral disorder Clin Orthop Relat Res 2003;409:169-174.[Medline]
- Ngan EM, Rebeyka IM, Ross DB, et al. The rapid prototyping of anatomic models in pulmonary atresia J Thorac Cardiovasc Surg 2006;132:264-269.[Abstract/Free Full Text]
- Sulaiman A, Boussel L, Taconnet F, et al. In vitro non-rigid life-size model of aortic arch aneurysm for endovascular prosthesis assessment Eur J Cardiothorac Surg 2008;33:53-57.[Abstract/Free Full Text]
- Angeli E, Pacini D, Martin-Suarez S, Dell'Amore A, Fattori R, Di Bartolomeo R. Stent repair of aortic perianastomotic leak after aortic arch and descending aorta replacement Ital Heart J 2004;5:951-953.[Medline]
This article has been cited by other articles:
|
|
|
|
 
D. Schmauss, C. Schmitz, A. K. Bigdeli, S. Weber, N. Gerber, A. Beiras-Fernandez, F. Schwarz, C. Becker, C. Kupatt, and R. Sodian
Three-Dimensional Printing of Models for Preoperative Planning and Simulation of Transcatheter Valve Replacement
Ann. Thorac. Surg.,
February 1, 2012;
93(2):
e31 - e33.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
