An experimental model for side-to-side microvascular anastomosis

Side-to-Side Microvascular Anastomosis Using Rat Cervical Vessels

BACKGROUND

Side-to-side anastomosis is the most challenging anastomosis owing to the difficult intraluminal suturing technique, which requires practice in the microsurgical laboratory before application in patients in the operating room. The objective of this study was to describe 2 side-to-side microvascular anastomosis training models using rat cervical vessels.

METHODS

Two side-to-side microvascular anastomosis training models, one with rat cervical vessels between bilateral common carotid arteries (CCAs) (CCA-CCA anastomosis) and one with a unilateral CCA and the anterior facial vein of the external jugular vein (EJV) (CCA-EJV anastomosis), were studied. Diameters of CCA and anterior facial vein, distances between temporary clips and length of arteriotomies, and vascular clipping time were recorded. Patency rates were evaluated immediately and 7 days after the procedure.

RESULTS

Diameters of CCA and anterior facial vein were 1.00-1.20 mm and 1.40-1.80 mm, respectively. A segment of vessel slightly longer than the arteriotomy or venotomy was temporarily clipped; mean lengths between temporary clips in CCA-CCA anastomosis and CCA-EJV anastomosis of 6.48 ± 0.66 mm and 8.02 ± 0.45 mm, respectively, were used in the study. The minimum distance between the corner of the arteriotomy or venotomy and the clip was 1 mm. The mean vascular temporary clipping times in CCA-CCA anastomosis and CCA-EJV anastomosis were 40.05 ± 3.92 minutes and 42.50 ± 4.82 minutes, respectively. Patency rates of 100% were achieved in all anastomoses.

CONCLUSIONS

CCA-CCA and CCA-EJV side-to-side anastomosis models using rat cervical vessels are feasible and effective side-to-side anastomosis training models.

Best Practices Using Ex Vivo Animal Brain Models in Neurosurgical Education to Assess Surgical Expertise

BACKGROUND

Ex vivo animal brain simulation models are being increasingly used for neurosurgical training because these models can replicate human brain conditions. The goal of the present report is to provide the neurosurgical community interested in using ex vivo animal brain simulation models with guidelines for comprehensively and rigorously conducting, documenting, and assessing this type of research.

METHODS

In consultation with an interdisciplinary group of physicians and researchers involved in ex vivo models and a review of the literature on the best practices guidelines for simulation research, we developed the "ex vivo brain model to assess surgical expertise" (EVBMASE) checklist. The EVBMASE checklist provides a comprehensive quantitative framework for analyzing and reporting studies involving these models. We applied The EVBMASE checklist to the studies reported of ex vivo animal brain models to document how current ex vivo brain simulation models are used to train surgical expertise.

RESULTS

The EVBMASE checklist includes defined subsections and a total score of 20, which can help investigators improve studies and provide readers with techniques to better assess the quality and any deficiencies of the research. We classified 18 published ex vivo brain models into modified (group 1) and nonmodified (group 2) models. The mean total EVBMASE score was 11 (55%) for group 1 and 4.8 (24.2%) for group 2, a statistically significant difference (P = 0.006) mainly attributed to differences in the simulation study design section (P = 0.003).

CONCLUSIONS

The present findings should help contribute to more rigorous application, documentation, and assessment of ex vivo brain simulation research.

Side-to-Side Anastomosis Training Model Using Rat Common Carotid Arteries

BACKGROUND

The side-to-side anastomosis is one of the difficult bypass configurations that may be used in various complex cerebral vascular and neoplastic cases. Few pure arterial models exist for practicing this bypass subtype.

OBJECTIVE

To provide an optimized side-to-side anastomosis training model using rat common carotid arteries (CCA).

METHODS

Bilateral CCAs were exposed in the neck of 10 anesthetized Sprague-Dawley rats. The arteries were juxtaposed in parallel, using temporary aneurysm clips applied proximally and distally. CCA caliber and the length of CCA juxtaposition were measured. Side-to-side anastomosis was completed and ischemia time was recorded. Unintended complications were recorded for further analysis.

RESULTS

Anastomosis was completed successfully in all animals. The CCAs were approximated in all animals without any difficulty or undue tension. In 2 rats, death occurred prior to completion of anastomosis, which was attributed to injury to the external jugular vein during vessel exposure. Mean ischemia time was 35 min with an average of 22 sutures done to complete the anastomosis. The average CCA caliber was 1.1 ± 0.2 mm and the arteries could be juxtaposed for an average length of 10.2 ± 1.5 mm.

CONCLUSION

Full exposure of the cervical segment of the CCAs enables tension-free approximation of adequate length of the vessel for a side-to-side anastomosis. Avoiding complications during exposure helps in prevention of animal death during the ischemia period.

Microsurgical Bypass Training Rat Model, Part 1: Technical Nuances of Exposure of the Aorta and Iliac Arteries

BACKGROUND

Animal models using rodents are frequently used for practicing microvascular anastomosis-an essential technique in cerebrovascular surgery. However, safely and efficiently exposing rat's target vessels is technically difficult. Such difficulty may lead to excessive hemorrhage and shorten animal survival. This limits the ability to perform multiple anastomoses on a single animal and may increase the overall training time and costs. We report our model for microsurgical bypass training in rodents in 2 consecutive articles. In part 1, we describe the technical nuances for a safe and efficient exposure of the rat abdominal aorta and common iliac arteries (CIAs) for bypass.

METHODS

Over a 2-year period, 50 Sprague-Dawley rats underwent inhalant anesthesia for practicing microvascular anastomosis on the abdominal aorta and CIAs. Lessons learned regarding the technical nuances of vessel exposure were recorded.

RESULTS

Several technical nuances were important for avoiding intraoperative bleeding and preventing animal demise while preparing an adequate length of vessels for bypass. The most relevant technical nuances include (1) generous subcutaneous dissection; (2) use of cotton swabs for the blunt dissection of the retroperitoneal fat; (3) combination of sharp and blunt dissection to isolate the aorta and iliac arteries from the accompanying veins; (4) proper control of the posterior branches of the aorta; and (5) efficient division and mobilization of the left renal pedicle.

CONCLUSIONS

Applying the aforementioned technical nuances enables safe and efficient preparation of the rat abdominal aorta and CIAs for microvascular anastomosis.

Validation of microsurgical models in microsurgery training and competence: A review

Microsurgery has expanded the scope of many surgical specialties and is evolving into an integral part of training programmes. The complexity of microsurgery requires considerable time and resources for adequate training and practice. This article reviews the validation of microsurgical models for microsurgery training and competence.

Learning to perform microvascular anastomosis

The skills necessary to connect ultrasmall vessels and neural structures successfully require commitment and practice to refine. The techniques require only a few specialized instruments and a high-quality microscope. Several exercises can simulate real-life anatomical situations using a rubber sheet, chicken vessels, or the rat femoral artery model. A series of graduated drills can help develop proficiency and confidence.

M2/M2 side-to-side rescue anastomosis for accidental M2 trunk occlusion during middle cerebral artery aneurysm clipping: technical note

OBJECTIVE

A technically feasible and rapid technique for revascularizing the main branches of the middle cerebral artery (MCA) is described. This technique is applied mainly when clipping of an MCA aneurysm is complicated and occlusion of the origin of an MCA main branch results.

METHODS

M2/M2 side-to-side anastomosis was applied in two patients in whom unplanned M2 occlusion occurred during the course of complicated MCA aneurysm clipping. The first patient underwent an emergency procedure after temporoparietal intracerebral hemorrhage. Unilateral mydriasis precluded preoperative angiographic workup, and a complex large MCA aneurysm was found as the source of hemorrhage. Shaping of the aneurysm neck by bipolar coagulation and clipping resulted in accidental occlusion of the superior trunk, and patency could not be regained despite multiple clip corrections. The second patient had an unruptured multilobulated aneurysm 8 mm in maximum diameter. Continuity of the inferior trunk was lost during clipping because of a tear at the origin. In both instances, side-to-side anastomosis was placed approximately 15 mm from the bifurcation, where the MCA main trunks ran side by side for a length of approximately 5 mm.

RESULTS

After intracerebral hemorrhage, the first patient recovered to a level of moderate disability within 2 months. Substantial hemiparesis and expressive dysphasia remained as sequelae of the intracerebral hemorrhage. Digital subtraction angiography 2 months after the emergency procedure confirmed patency of the side-to-side anastomosis. The second patient was neurologically intact after recovery from anesthesia. Before discharge from the hospital on postoperative Day 8, digital subtraction angiography confirmed patency of the anastomosis.

CONCLUSION

The MCA main branches usually run in close proximity for a short segment at the bottleneck entrance to the insular cistern. M2/M2 side-to-side anastomosis at this site is a rapid and feasible mode of revascularization of an M2 trunk accidentally occluded during complicated MCA aneurysm clipping.