Role of Simulated Training for Carotid Endarterectomy: A Systematic Review

Vascular surgery trainees often do not get to perform carotid endarterectomy (CEA) directly on the patients as it requires meticulous surgical technique and has a high risk of procedure-related complications. Hence, the role of simulation in training future vascular surgeons becomes essential. This review aims to assess the types and utility of simulators available for CEA. In this systematic review, all the studies performed on CEA simulation were included. The purpose of this review was to assess different types of simulators and their usefulness for CEA. We identified 122 articles, of which 10 were eligible for review. A variety of simulators, ranging from animal models, virtual reality simulators and commercially designed models with high fidelity options were used. Technical competence was the major domain assessed in the majority of the studies (n=8), whereas four studies evaluated anatomical and procedural knowledge. Blinding was done in five studies for assessment purposes. The majority of studies (n=9) found the simulation to be an effective tool for achieving technical competence. This review shows the potential usefulness of simulation in acquiring technical skills and procedural acumen for CEA. The available literature is unfortunately too diverse to have a common recommendation.

Dye-Perfused Human Placenta for Vascular Microneurosurgery Training: Preparation Protocol and Validation Testing

BACKGROUND

Human placenta is recognized as a valuable vascular microneurosurgery training model because of its abundant availability, ethical acceptance, and analogous vasculature with other vessels of the human body; however, human placenta laboratory preparation techniques are not well described in the literature. This study outlines a detailed and standardized laboratory protocol for preparation of a color-perfused human placenta model. Survey-based validation of the model is also reported herein.

METHODS

The protocol involved cleaning and cannulation of the umbilical vein and arteries, irrigation with heparin, and storage at 3°C or freezing at -18°C. Before use, arteries were perfused with carmine/cochineal, and veins were perfused with methylthioninium chloride. A questionnaire with 5 questions was administered to 40 participants among attending or resident neurosurgeons, otolaryngologists, and maxillofacial surgeons on 4 consecutive microsurgical courses to assess the reliability of the placenta model. Trainees were divided into 3 groups based on their experience. A χ² test was used to identify differences between groups.

RESULTS

Forty-two placentas were considered appropriate for training and were successfully perfused with dyes. Thirty-three participants completed the questionnaire, of which most, especially advanced and intermediate participants, indicated the placenta as a valuable, accurate, and reproducible model. No differences were observed among the groups.

CONCLUSIONS

The human placenta is an excellent tool for vascular microneurosurgery laboratory training. Color perfusion enhances the reliability of this model, which was validated by most surgeons, regardless of their experience.

Development of a Whole-Task Simulator for Carotid Endarterectomy

BACKGROUND

Surgical education relies on operative exposure with live patients. Carotid endarterectomy (CEA) demands an experienced surgeon with a very low complication rate. The high-risk nature of this procedure and the decline in number of CEAs performed annually has created a gap in residency training.

OBJECTIVE

To develop a high-fidelity whole-task simulation for CEA that demonstrates content, construct, and face validity.

METHODS

Anatomically accurate models of the human neck were created using multilayered poly-vinyl alcohol hydrogels. Graded polymerization of the hydrogel was achieved by inducing crosslinks during freeze/thaw cycles, stiffening the simulated tissues to achieve realistic tactile properties. Venous bleeding was simulated using pressure bags and a ventricular assistive device created pulsatile flow in the carotid. Ten surgeons performed the simulation under operating room conditions, and metrics were compared among experience levels to determine construct validity. Participants completed surveys about realism and usefulness to evaluate face validity.

RESULTS

A significant difference was found in operative measures between attending and resident physicians. The mean operative time for the expert group was 63.6 min vs 138.8 for the resident group (P = .002). There was a difference in mean internal carotid artery clamp time of 43.4 vs 83.2 min (P = .04). There were only 2 hypoglossal nerve injuries, both in the resident group (P = .009).

CONCLUSION

The whole-task CEA simulator is a realistic, inexpensive model that offers comprehensive training and allows residents to master skills prior to operating on live patients. Overall, the model demonstrated face and construct validity among neurosurgery and vascular surgeons.

Decellularized bovine cotyledons may serve as biological scaffolds with preserved vascular arrangement

Technically produced scaffolds are common to establish transplantable tissues for regenerative medicine, but also biological ones that are closer to the natural condition become of interest. Placentas are promising, because they represented available, complete organs with rich extracellular matrix (ECM) and well-developed vasculature that easily could build anastomoses to a host's organ. Only placentas from larger animal models such as the bovine meet the dimensions large enough for most organs but are not adequately described yet. We here studied the nature of the ECM in 27 natural and decellularized bovine cotyledons, that is, the fetal part of the placentomes, by means of histology, immunohistochemistry, and electron microscopy. Successful decellularization was done by perfusion with 0.01%, 0.1%, and 0.5% sodium dodecyl sulfate each and subsequent immersion in 1% Triton X-100, resulting in a removal of cells and DNA, whereas the structure of the allantochorionic surface and villi was preserved. Although some fibres disappeared, also the arrangement of the main ECM proteins was largely similar before and after decellularization: Along the larger vessels, a densely packed network of thick fibres occurred, organized in layers without cells or spaces in between. Collagen IV, fibronectin, and laminin contributed to those areas. In contrast, collagen I and III characterized the meshwork of medium-sized and thin fibres in the mesenchyme, respectively. In conclusion, decellularized bovine cotyledons indeed had characteristics of a biological scaffold and provide an interesting alternative to develop large-scale scaffolds with complex vascular architecture for tissue engineering purposes.