Planning the use of endografts in the endovascular repair of complex abdominal and thoraco-abdominal aortic lesions leveraging 3D printing

INTRODUCTION

Endovascular techniques and materials have significantly expanded their application in the treatment of abdominal and thoraco-abdominal aortic lesions, allowing for the management of increasingly complex pathologies that may require cannulation of target vessels. The treatment of such diseases deserves a particular approach and dedicated materials, for which correct procedural planning is mandatory. In the last decades, the use of 3D printing technology as an assisting tool for preoperative rehearsal of complex cases has progressively widespread.

AREAS COVERED

A review was performed about the use of 3D printing technology for the planning of endovascular repair of complex abdominal and thoraco-abdominal aortic lesions. Also, our experience of planning and simulation of an elective challenging endovascular procedure for a Crawford's type II thoraco-abdominal aortic aneurysm using a Cook Zenith® T-BranchTM endograft, leveraging a 3D-printed model of the patient-specific anatomy from the aortic arch to the common femoral artery, is herein described.

EXPERT OPINION

The benefits of using 3D printing technologies as an assistive tool in planning complex endovascular repairs of abdominal and thoraco-abdominal aortic lesions have been well-documented in the literature, including their application in urgent cases. However, further research and development are necessary to overcome the current limitations of this potentially highly valuable technology.

Elaboration and development of a realistic 3D printed model for training in ultrasound-guided placement of peripheral central venous catheter in children

BACKGROUND

Simulation for training is becoming a trend topic worldwide, even if its applications are commonly limited to adulthood. Ultrasound-guided procedures require practice and experience-especially in the pediatric field, where the small size of the involved anatomical structures poses major problems. In this context, a realistic 3D printed pediatric phantom for training of the ultrasound-guided placement of peripheral central venous catheters in children was developed.

MATERIALS AND METHODS

Starting from Computed Tomography scans of an 8 years-old girl, her left arm was virtually reconstructed-including bones, arteries, and veins-through a semi-automatic segmentation process. According to preliminary results, the most suitable 3D printing technologies to reproduce the different anatomical structures of interest were selected, considering both direct and indirect 3D printing techniques. Experienced operators were asked to evaluate the efficacy of the final model through a dedicated questionnaire.

RESULTS

Vessels produced through indirect 3D printing latex dipping technique exhibited the best echogenicity, thickness, and mechanical properties to mimic real children's venous vessels, while arteries-not treated and/or punctured during the procedure-were directly 3D printed through Material Jetting technology. An external mold-mimicking the arm skin-was 3D printed and a silicone-based mixture was poured to reproduce real patient's soft tissues. Twenty expert specialists were asked to perform the final model's validation. The phantom was rated as highly realistic in terms of morphology and functionality for the overall simulation, especially for what concerns vessels and soft tissues' response to puncturing. On the other hand, the involved structures' US appearance showed the lower score.

CONCLUSIONS

The present work shows the feasibility of a patient-specific 3D printed phantom for simulation and training in pediatric ultrasound-guided procedures.

Clinical comparative analysis of 3D printing-assisted extracorporeal pre-fenestration and Castor integrated branch stent techniques in treating type B aortic dissections with inadequate proximal landing zones

BACKGROUND

This study aims to compare the clinical effects of two distinct surgical approaches, namely 3D printing-assisted extracorporeal pre-fenestration and Castor integrated branch stent techniques, in treating patients with Stanford type B aortic dissections (TBAD) characterized by inadequate proximal landing zones.

METHODS

A retrospective analysis was conducted on 84 patients with type B aortic dissection (TBAD) who underwent thoracic endovascular aortic repair (TEVAR) with left subclavian artery (LSA) reconstruction at our center from January 2022 to July 2023. Based on the different surgical approaches, the patients were divided into two groups: the group assisted by 3D printing for extracorporeal pre-fenestration (n = 44) and the group using the castor integrated branch stent (n = 40). Clinical indicators: including general patient information, operative time, surgical success rate, intraoperative and postoperative complication rates, re-intervention rate, and mortality, as well as postoperative aortic remodeling, were compared between the two groups. The endpoint of this study is the post-TEVAR mortality rate in patients.

RESULTS

The surgical success rate and device deployment success rate were 100% in both groups, with no statistically significant difference (P > 0.05). However, the group assisted by 3D printing for extracorporeal pre-fenestration had a significantly longer operative time (184.20 ± 54.857 min) compared to the group using the castor integrated branch stent (152.75 ± 33.068 min), with a statistically significant difference (t = 3.215, p = 0.002, P < 0.05). Moreover, the incidence of postoperative cerebral infarction and beak sign was significantly lower in the group assisted by 3D printing for extracorporeal pre-fenestration compared to the castor-integrated branch stent group, demonstrating statistical significance. There were no significant differences between the two groups in terms of other postoperative complication rates and aortic remodeling (P > 0.05). Notably, computed tomography angiography images revealed the expansion of the vascular true lumen and the reduction of the false lumen at three specified levels of the thoracic aorta. The follow-up duration did not show any statistically significant difference between the two groups (10.59 ± 4.52 vs. 9.08 ± 4.35 months, t = 1.561, p = 0.122 > 0.05). Throughout the follow-up period, neither group experienced new endoleaks, spinal cord injuries, nor limb ischemia. In the castor-integrated branch stent group, one patient developed a new distal dissection, prompting further follow-up. Additionally, there was one case of mortality due to COVID-19 in each group. There were no statistically significant differences between the two groups in terms of re-intervention rate and survival rate (P > 0.05).

CONCLUSION

Both 3D printing-assisted extracorporeal pre-fenestration TEVAR and castor-integrated branch stent techniques demonstrate good safety and efficacy in treating Stanford type B aortic dissection with inadequate proximal anchoring. The 3D printing-assisted extracorporeal pre-fenestration TEVAR technique has a lower incidence of postoperative cerebral infarction and beak sign, while the castor-integrated branch stent technique has advantages in operative time.

Quality Control in 3D Printing: Accuracy Analysis of 3D-Printed Models of Patient-Specific Anatomy

As comparative data on the precision of 3D-printed anatomical models are sparse, the aim of this study was to evaluate the accuracy of 3D-printed models of vascular anatomy generated by two commonly used printing technologies. Thirty-five 3D models of large (aortic, wall thickness of 2 mm, n = 30) and small (coronary, wall thickness of 1.25 mm, n = 5) vessels printed with fused deposition modeling (FDM) (rigid, n = 20) and PolyJet (flexible, n = 15) technology were subjected to high-resolution CT scans. From the resulting DICOM (Digital Imaging and Communications in Medicine) dataset, an STL file was generated and wall thickness as well as surface congruency were compared with the original STL file using dedicated 3D engineering software. The mean wall thickness for the large-scale aortic models was 2.11 µm (+5%), and 1.26 µm (+0.8%) for the coronary models, resulting in an overall mean wall thickness of +5% for all 35 3D models when compared to the original STL file. The mean surface deviation was found to be +120 µm for all models, with +100 µm for the aortic and +180 µm for the coronary 3D models, respectively. Both printing technologies were found to conform with the currently set standards of accuracy (<1 mm), demonstrating that accurate 3D models of large and small vessel anatomy can be generated by both FDM and PolyJet printing technology using rigid and flexible polymers.

Accessing 3D Printed Vascular Phantoms for Procedural Simulation

Introduction: 3D printed patient-specific vascular phantoms provide superior anatomical insights for simulating complex endovascular procedures. Currently, lack of exposure to the technology poses a barrier for adoption. We offer an accessible, low-cost guide to producing vascular anatomical models using routine CT angiography, open source software packages and a variety of 3D printing technologies.

Methods: Although applicable to all vascular territories, we illustrate our methodology using Abdominal Aortic Aneurysms (AAAs) due to the strong interest in this area. CT aortograms acquired as part of routine care were converted to representative patient-specific 3D models, and then printed using a variety of 3D printing technologies to assess their material suitability as aortic phantoms. Depending on the technology, phantoms cost $20–$1,000 and were produced in 12–48 h. This technique was used to generate hollow 3D printed thoracoabdominal aortas visible under fluoroscopy.

Results: 3D printed AAA phantoms were a valuable addition to standard CT angiogram reconstructions in the simulation of complex cases, such as short or very angulated necks, or for positioning fenestrations in juxtarenal aneurysms. Hollow flexible models were particularly useful for device selection and in planning of fenestrated EVAR. In addition, these models have demonstrated utility other settings, such as patient education and engagement, and trainee and anatomical education. Further study is required to establish a material with optimal cost, haptic and fluoroscopic fidelity.

Conclusion: We share our experiences and methodology for developing inexpensive 3D printed vascular phantoms which despite material limitations, successfully mimic the procedural challenges encountered during live endovascular surgery. As the technology continues to improve, 3D printed vascular phantoms have the potential to disrupt how endovascular procedures are planned and taught.

Robotic Treatment of Complex Splenic Artery Aneurysms with Deep Hilar Location: Technical Insights and Midterm Results

BACKGROUND

Splenic artery aneurysms are rare, but their occurrence is burdened by considerable mortality and morbidity rates. Although the indications to treatment are quite clear-cut, there is still debate on the first-choice technique of treatment (endovascular, open, or laparoscopic surgery). Recently, robotic surgery has been proposed as an alternative option in patients at high surgical risk. The present case series aims to assess the value of robotic treatment of splenic artery aneurysms in patients unfit for surgery.

METHODS

All cases of splenic artery aneurysms treated by robotic surgery at our center between 2014 and 2018 were retrospectively reviewed. Primary endpoints were clinical and technical success and disease-free survival.

RESULTS

Robotic surgery was used to treat four patients affected by splenic artery aneurysms, with the guidance of 3D printed patient-specific models. All patients, after aneurysm excision, received reconstruction of the splenic artery by direct anastomosis. All cases were treated successfully without mortality. Reintervention-free survival at 24-month mean follow-up is 100%, and no systemic complication of clinical relevance was reported. The mean time of organ ischemia was 45 min.

CONCLUSIONS

Robotic surgery is a safe and effective option in treating visceral aneurysms, providing the possibility to reconstruct the splenic artery after aneurysm excision.

Three-dimensional printing-guided fenestrated endovascular aortic aneurysm repair using open source software and physician-modified devices

Fenestrated endovascular aneurysm repair is frequently used for juxtarenal and pararenal aortic aneurysms. In urgent cases, however, the use of premanufactured patient-specific devices is not an option. Physician-modified endografts may be used to treat these patients but require experience and a steep learning curve for accurate planning to position fenestrations and to perform the graft modifications. Despite experience, a margin of error in placing fenestrations always exists, and a mismatch possibility between the fenestration and vessel ostium can lead to increased cannulation time and stent complications, including target vessel loss. Aortic three-dimensional printing has been widely described in medicine for simulation, training, and surgical planning. Commercial software is currently under investigation for planning of fenestrated endovascular aneurysm repair at high costs. We describe an effective and inexpensive technique using free computer-aided design software to create a real 1:1 aortic 3D model that can easily be printed and quickly sterilized. This aortic model can be used to create a physician-modified endograft and to place fenestrations in an accurate way, with potential for shorter and more precise procedures and better long-term results. Two cases are presented to illustrate the technique, demonstrating that 3D printing is a valuable tool to plan, design, and create fenestrated devices more accurately.

Trends in use of 3D printing in vascular surgery: a survey

INTRODUCTION

The purpose of the following research was to provide a systematic survey on the use of additive manufacturing in vascular surgery. The survey focuses on applications of 3D printing in endovascular surgery like endovascular aneurysm repair (EVAR), a quite unexplored application domain. 3D printing is an additive production process of three-dimensional objects starting from a three-dimensional digital model. This kind of manufacturing process is getting great attention in the medical field and new applications have emerged in recent years especially thanks to the combination of additive printing with 3D imaging techniques. The purpose of the study is to reflect on additive manufacturing and its potential as an inclusive manufacturing practice which can provide benefits at economic and societal level.

EVIDENCE ACQUISITION

The article first introduces the use of 3D printing in surgery by summarizing the results of previous reviews which reveal three main usages of 3D printing: anatomic models, surgical tools, implants and prostheses. These studies point out that vascular surgery is still an unexplored field of application of 3D printing. Starting from this result, a new survey was carried out in databases Pubmed, Elsevier, Research Gate and ACM Digital Library for terms related to 3D printing in vascular surgery using the following keywords: 3D printing, vascular surgery, EVAR, aneurysm. The search screened articles published up to 2019 for relevance and practical application of the technology in vascular surgery, in particular the topic is related to the treatment of complex abdominal aortic aneurysm.

EVIDENCE SYNTHESIS

Initially 437 records published up to 2019 were found, but then were narrowed down to 29 full-text articles. The findings reveal that in addition to the applications found in the previous studies, new experiments are ongoing related to the use of 3D printing in the "Off label" practice to manually fenestrate the stent to improve the accuracy of the EVAR.

CONCLUSIONS

Different applications of the use of 3D printing and digital imaging in vascular surgery have been experimented with a different maturity level. Whilst the technology has increased its potential in the latest years, the number of studies documented in the literature is still quite narrow. Further research is necessary to fully test the potential of 3D printing, also in combination with other technologies (e.g. 3D imaging and CNC cutting). Early experimentations show that these technologies have the potential to radically change the vascular surgery practice in the near future, in particular in treatment like EVAR, to improve the planning and therefore the success of the surgery.

Design, simulation, and fabrication of a three-dimensional printed pump mimicking the left ventricle motion

The development of accurate replicas of the circulatory and cardiac system is fundamental for a deeper understanding of cardiovascular diseases and the testing of new devices. Although numerous works concerning mock circulatory loops are present in the current state of the art, still some limitations are present. In particular, a pumping system able to reproduce the left ventricle motion and completely compatible with the magnetic resonance environment to permit the four-dimensional flow monitoring is still missing. The aim of this work was to evaluate the feasibility of an actuator suitable for cardiovascular mock circuits. Particular attention was given to the ability to mimic the left ventricle dynamics including both compression and twisting with the magnetic resonance compatibility. In our study, a left ventricle model to be actuated through vacuum was designed. The realization of the system was evaluated with finite element analysis of different design solutions. After the in silico evaluation phase, the most suitable design in terms of physiological values reproduction was fabricated through three-dimensional printing for in vitro validation. A pneumatic experimental setup was developed to evaluate the pump performances in terms of actuation, in particular ventricle radial and longitudinal displacement, twist rotation, and ejection fraction. The study demonstrated the feasibility of a custom pneumatic pump for mock circulatory loops able to reproduce the physiological ventricle movement and completely suitable for the magnetic resonance environment.

3D printing of aortic models as a teaching tool for improving understanding of aortic disease

BACKGROUND

A geometrical understanding of the individual patient's disease morphology is crucial in aortic surgery. The aim of our study was to validate a questionnaire addressing understanding of aortic disease and use this questionnaire to investigate the value of 3D printing as a teaching tool for surgical trainees.

METHODS

Anonymized CT-angiography images of six different patients were selected as didactic cases of aortic disease and made into 3D models of transparent rigid resin with the Vat-photopolymerization technique. The 3D aortic models, which could be disassembled and reassembled, were displayed to 37 surgical trainees, immediately after a seminar on aortic disease. A questionnaire was developed to compare the trainees' understanding before (T0) and after (T1) demonstration of the 3D printed models.

RESULTS

A panel of 15 experts participated in evaluating face and content validity of the questionnaire. The questionnaire validity was established and therefore the information investigated by the questionnaire could be synthetized using the mean of the items to indicate the understanding. The participants (mean age 28 years, range 26-34, male 59%) showed a significant improvement in understanding from T0 (median=7.25; IQR=1.50) to T1 (median=8.00; IQR=1.50; P=0.002).

CONCLUSIONS

Preliminary data suggest that the use of 3D-printed aortic models as a teaching tool was feasible and improved the understanding of aortic disease among surgical trainees.

Three-dimensional printed cardiac fistulae: a case series

BACKGROUND

Three-dimensional (3D) printing of cardiac fistulae allows for immediate understanding of their complex courses and anatomical relations. Models can be used to improve patient understanding, enhance the consenting process, facilitate communication between multidisciplinary staff at heart team meetings, and help plan surgical or percutaneous interventions.

CASE SUMMARY

We report four cases where 3D printed models were used as an adjunct with traditional measures in treating patients with complex cardiac fistulae.

DISCUSSION

In our cases, overall patient understanding was improved, staff at heart team meetings were more aware of anatomical anomalies and perioperatively planning saw adjustments made that may have ultimately benefited patient outcome. Our cases highlight the additional benefit that 3D printed models can play when treating patients with complex cardiac fistulae.