How I do it: Endoscope-assisted in situ arterial reconstruction of the lower limb.

Arterial reconstruction with the great saphenous vein is a frequently performed vascular surgery technique for revascularization of chronic limb threatening ischemia. Surgeon variations of the procedure are common and aim to balance patency, limb salvage, complications, hospital resources, and technical feasibility. We describe a minimally invasive revascularization option using endoscope assistance for in situ great saphenous vein-arterial bypass to treat infrainguinal occlusive disease. We highlight patient selection, operating room setup, instrument details, and procedure strategies that facilitate the use of this technique. The development and refinement of minimally invasive techniques for lower extremity arterial bypass are critical to reduce wound complications and improve limb salvage outcomes in patients.

Angiographic and Clinical Outcomes of Various Techniques of Intracranial-to-Intracranial Bypass for Complex Cases with a Review of Pertinent Literature and Illustrated Cases.

BACKGROUND: We sought to determine the utility of intracranial-to-intracranial bypass (IIB) surgery and the available bypass options for complex cases. METHODS: A total of 18 IIB cases were included. Each case was classified as IIB with or without an interposition graft. The clinical and angiographic status were evaluated pre- and postoperatively and at the last follow-up. Angiographic images were analyzed and reconstructed schematically. Postoperative angiography was used to measure the bypass patency and the presence of postoperative cerebral infarction. The recipient artery occlusion time for each bypass was measured. RESULTS: Of the 18 patients, 14 had presented with a complex intracranial aneurysm (IA), 1 with vertebrobasilar dolichoectasia, and 3 with intracranial arterial steno-occlusive disease. Ten patients had an incidentally discovered IA. Seven patients had presented with neurological deficits due to ischemia or aneurysmal mass effects. Of the 18 cases, 10 were IIBs with an interposition graft, including 4 cases of superficial temporal artery and 6 of radial artery graft bypass, and 8 were IIBs with a noninterposition graft, including 3 cases of in situ bypass, 1 case of reanastomosis, and 4 cases of reimplantation. The pre- and postoperative modified Rankin scale score did not change or improve, and all the bypasses were patent. No patient had died during the mean follow-up period of 50.0 months. The mean occlusion time of the recipient artery was 59.5 minutes. A total of 8 patients experienced postoperative cerebral infarction but all had almost recovered at discharge. CONCLUSIONS: With proper selection of the IIB type, IIB can be a suitable treatment option for some patients with complex IAs and intracranial arterial steno-occlusive disease when extracranial-to-intracranial bypass is not feasible.

The surgical strategy and technical nuances of in situ side-to-side bypass for the management of complex intracranial aneurysms.

Background: Despite continuous advances in microsurgical and endovascular techniques, the treatment of complex aneurysms remains challenging. Aneurysms that are dilemmatic for conventional clipping or endovascular coiling often require bypass as part of a strategy to reduce the risk of ischemic complications. In anatomically favorable sites, the intracranial-intracranial in situ bypass may be an appealing choice. This article details the surgical strategies, operative nuances, and clinical outcomes of this technique with a consecutive series in our department. Methods: A retrospective review of a prospectively maintained neurosurgical patient database was performed to identify all patients treated with side-to-side in situ bypass from January 2016 to June 2022. In total, 12 consecutive patients, including 12 aneurysms, were identified and included in the series. The medical records, surgical videos, neuroimaging studies, and follow-up clinic notes were reviewed for every patient. Results: Of the 12 aneurysms, there were 5 middle cerebral artery aneurysms, 4 anterior cerebral artery aneurysms, and 3 posterior inferior cerebellar artery aneurysms. The morphology of the aneurysms was fusiform in 8 patients and saccular in the remaining 4 patients. There were 3 patients presented with subarachnoid hemorrhage. The treatment modality was simple in situ bypass in 8 cases and in situ bypass combined with other modalities in 4 cases. Bypass patency was confirmed in all cases by intraoperative micro-doppler probe and (or) infrared indocyanine green (ICG) video angiography intraoperatively and with digital subtraction angiography (DSA) or computed tomography angiography (CTA) postoperatively. None of the patients developed a clinically manifested stroke due to the procedure though a callosomarginal artery was intentionally removed in one patient. The median follow-up period was 16.2 months (6-36). All patients had achieved improved or unchanged modified Rankin scale scores at the final follow-ups. Conclusion: Cerebral revascularization technique remains an essential skill for the treatment of complex aneurysms. The in situ bypass is one of the most effective techniques to revascularize efferent territory when vital artery sacrifice or occlusion is unavoidable. The configuration of in situ bypass should be carefully tailored to each case, with consideration of variations in anatomy and pathology of the complex aneurysms.

Complication of Middle Cerebral Artery Aneurysm Surgery: An M2 Tear at the Neck, Managed with a Salvage M2-to-M2 In Situ Bypass.

An unexpected rupture at the aneurysm neck, with or without adjacent arterial injury or compromise of distal branches during microsurgical clipping, can be a challenging surgical problem to resolve. In this presented case of a neurologically intact 65-year-old woman, elective clipping of an unruptured right middle cerebral artery bifurcation aneurysm was complicated by an unexpected M2 tear at the neck, involving the origin of the frontal M2. Attempts to seal the tear directly, using various techniques, failed; therefore, it was ultimately managed with sacrifice of the vessel and a salvage side-to-side M2-to-M2 in situ bypass. Six months after surgery, the patient demonstrated moderate disability but was able to ambulate with a cane.

The M2-M1 middle cerebral artery reimplantation bypass with protective superficial temporal artery to middle cerebral artery bypass for giant partially thrombosed middle cerebral artery aneurysm in the hybrid operating suite.

BACKGROUND: Giant middle cerebral artery (MCA) aneurysms are complex and challenging. Revascularization is frequently required in addition to trapping or clip reconstruction, and the MCA reimplantation bypass is ultimately needed when aneurysm excision is planned. METHOD: The operation was conducted in the hybrid operating suite, where an intraoperative cerebral angiography revealed a compromised MCA after multiple attempts of clip reconstruction. Therefore, we decided to perform an M2-M1 reimplantation bypass in conjunction with trapping and aneurysmectomy. CONCLUSION: Reimplantation bypass can be a rescue procedure for revascularization in complex aneurysms. The angioarchitecture varies among individuals; therefore, the optimal bypass technique should be tailored.

The application of high-resolution vessel wall imaging in the in situ bypass surgeries for complex anterior cerebral artery aneurysms.

OBJECTIVE: Complex anterior cerebral artery (ACA) aneurysms are still technically challenging to treat. Bypass surgery is needed to achieve aneurysm obliteration and ACA territory revascularization. Severe atherosclerosis of aneurysm walls can cause clip slippage, intraoperative rupture, postoperative ischemic events. How to assess the atherosclerotic changes in vascular walls by high-resolution vessel wall magnitude resonance imaging (VWI) is the key question in complex ACA aneurysm surgical management. METHODS: This retrospective single-center study included eight patients diagnosed with complex anterior cerebral arteries admitted to our hospital for bypass surgery from January 2019 to April 2022. We discussed the application of VWI in aneurysms treated with in situ bypass and reviewed previous experience of revascularization strategies for complex ACA aneurysms. RESULTS: In this study, we treated 8 cases of complex ACA aneurysms (3 communicating aneurysms/5 postcommunicating aneurysms) over the prior one year. In situ side-to-side anastomosis (1 A2-to-A2/6 A3-to-A3) was performed in seven cases, and trapping combined with excision was performed in another case. Following bypass, complete trapping was performed in 4 cases, and proximal clipping was performed in 3 cases. No surgery-related neurological dysfunctions were observed. The final modified Rankin scale was 0 in seven of the eight cases and 2 in one case. CONCLUSION: High-resolution VWI, as a favorable preoperative assessment tool, provides insight into patient-specific anatomy and microsurgical options before operations, which can help neurosurgeons develop individualized and valuable surgical plans.

Trapping and A4-A4 end-to-side anastomosis for the treatment of a ruptured A3 fusiform aneurysm: Potential risk of in-situ bypass.

The treatment of complicated anterior cerebral artery aneurysms remains challenging. Here, the authors describe a case of ruptured complicated A3 aneurysm, which was treated with trapping and in-situ bypass. A 47-year-old man presented to the emergency department with severe headache and vomiting. Computed tomography illustrated acute intracerebral hemorrhage in the right frontal lobe. Digital subtraction angiography (DSA) confirmed a ruptured fusiform A3 aneurysm with lobulation and a daughter sac. Trapping of the ruptured fusiform A3 aneurysm and distal end-toside A4 anastomosis was performed. DSA on postoperative day 7 showed mild vasospasm to the afferent artery. However, 2 months later, DSA demonstrated that the antegrade flow through the anastomosis site had recovered. Thus, surgeons should be aware of the possibility of postsurgical vasospasm of anastomosed arteries, especially in cases of ruptured aneurysms.

Saphenous vein dilation as an alternative to prosthetic femoral-distal bypass revascularization.

A 63-year-old man with a history of bipolar and schizoaffective disorder was admitted to the psychiatry unit. His comorbidities included active smoking, hypertension, diabetes, hyperlipidemia, coronary artery disease after coronary artery bypass grafting, and peripheral arterial disease. During the admission, the patient began to complain of right foot pain at rest. Angiography revealed occlusion of a previously placed right superficial femoral artery and popliteal stents, severe common femoral and distal popliteal stenosis with only a patent posterior tibial (PT) artery runoff. Serial venoplasty was performed and revealed an inadequately sized, ipsilateral great saphenous vein, followed by a delayed femoral-PT in situ saphenous vein bypass. Angiography at 32 months demonstrated a patent femoral-PT great saphenous vein bypass.

In-situ bypass is associated with superior infection-free survival compared with extra-anatomic bypass for the management of secondary aortic graft infections without enteric involvement.

OBJECTIVE: The optimal revascularization modality following complete resection of aortic graft infection (AGI) without enteric involvement remains unclear. The purpose of this investigation is to determine the revascularization approach associated with the lowest morbidity and mortality using real-world data in patients undergoing complete excision of AGI. METHODS: A retrospective, multi-institutional study of AGI from 2002 to 2014 was performed using a standardized database. Baseline demographics, comorbidities, and perioperative variables were recorded. The primary outcome was infection-free survival. Descriptive statistics, Kaplan-Meier survival analysis, and univariate and multivariable analyses were performed. RESULTS: A total of 241 patients at 34 institutions from seven countries presented with AGI during the study period (median age, 68 years; 75% male). The initial aortic procedures that resulted in AGI were 172 surgical grafts (71%), 66 endografts (27%), and three unknown (2%). Of the patients, 172 (71%) underwent complete excision of infected aortic graft material followed by in situ (in-line) bypass (ISB), including antibiotic-treated prosthetic graft (35%), autogenous femoral vein (neo-aortoiliac surgery) (24%), and cryopreserved allograft (41%). Sixty-nine patients (29%) underwent extra-anatomic bypass (EAB). Overall median Kaplan-Meier estimated survival was 5.8 years. Perioperative mortality was 16%. When stratified by ISB vs EAB, there was a significant difference in Kaplan-Meier estimated infection-free survival (2910 days; interquartile range, 391-3771 days vs 180 days; interquartile range, 27-3750 days; P < .001). There were otherwise no significant differences in presentation, comorbidities, or perioperative variables. Multivariable Cox regression showed lower infection-free survival among patients with EAB (hazard ratio [HR], 2.4; 95% confidence interval [CI], 1.6-3.6; P < .001), polymicrobial infection (HR, 2.2; 95% CI, 1.4-3.5; P = .001), methicillin-resistant Staphylococcus aureus infection (HR, 1.7; 95% CI, 1.1-2.7; P = .02), as well as the protective effect of omental/muscle flap coverage (HR, 0.59; 95% CI, 0.37-0.92; P = .02). CONCLUSIONS: After complete resection of AGI, perioperative mortality is 16% and median overall survival is 5.8 years. EAB is associated with nearly a two and one-half-fold higher reinfection/mortality compared with ISB. Omental and/or muscle flap coverage of the repair appear protective.

Surgical Strategies for Cerebral Revascularization in Patients with Limited Bypass Conduit Options and Unexpected Intraoperative Difficulties.

BACKGROUND: Cerebral bypass procedures are complex and require substantial experience and skills and thorough preoperative planning. Cerebrovascular surgeons face increasingly complex bypass cases because most routine cases are managed by endovascular means, and because increasing numbers of patients have complex medical problems that affect available and suitable bypass conduit options. We report the cases of several patients undergoing cerebral bypass with limited bypass conduit alternatives, in whom there were unexpected intraoperative difficulties requiring complex solutions. METHODS: The neurological surgery department database was reviewed to identify patients who had undergone cerebral bypass procedures during a 13-year period in whom there were limited available bypass conduits, and in whom unexpected intraoperative difficulties were encountered during cerebral bypass. RESULTS: Patient outcomes and graft patency were evaluated for 13 patients including 6 with ischemia, 3 with giant aneurysms, 2 with mycotic aneurysms, 1 with dissecting aneurysm, and 1 with gunshot-induced pseudoaneurysm. Median duration of follow-up was 43 months. In 12 of 13 patients, bypass graft/grafts were patent on the last computed tomography angiogram. In 1 patient, a prophylactic bypass procedure, the graft was not filling, probably because of lack of demand. Two patients died during follow-up of unrelated causes. CONCLUSIONS: Cerebrovascular surgeons should be versatile in dealing with patients with complex bypass. When there are limited available conduit options, we find that collaboration with other surgical specialties (e.g., plastics and vascular) is helpful. In patients in whom extreme intraoperative difficulties are expected, thorough preoperative planning with multiple backup plans should be exercised, as described in this report.

Anterior Cerebral Artery Bypass for Complex Aneurysms: Advances in Intracranial-Intracranial Bypass Techniques.

BACKGROUND: Anterior cerebral artery (ACA) bypasses for complex aneurysms are infrequently performed, yet previous experience demonstrates the importance of intracranial-intracranial bypasses. Here we describe technical advances in intracranial-intracranial bypass techniques and their clinical results. METHODS: Twenty-three patients with complex aneurysms requiring ACA bypasses were retrospectively studied. Ten patients were treated in period 1 (1997-2013) and 13 in period 2 (2014-2018). RESULTS: There were 3 precommunicating, 8 communicating, and 8 postcommunicating ACA aneurysms, plus 4 middle cerebral artery aneurysms. ACA in situ bypass was the most commonly performed (9 patients; 39%). The classic left A3 ACA-right A3 ACA in situ bypass was performed in 5 patients, but 3 new in situ variations emerged in period 2: left pericallosal artery (PcaA)-right PcaA (n = 1), left callosomarginal artery (CmaA)-right CmaA (n = 2), and left CmaA-right A3 ACA (n = 1). The sole reimplantation in period 1 was the ipsilateral and vertical PcaA-CmaA reimplantation, whereas reimplantations in period 2 were contralateral and horizontal (left PcaA-right PcaA and right A3 ACA-left anterior internal frontal artery). The A1 ACA was used as a donor only in period 2 in 4 patients with middle cerebral artery bifurcation aneurysms. Bypass patency was 91%, and 21 patients (91%) improved or remained at neurologic baseline (mean [standard deviation] follow-up duration, 26 [8.2] months). CONCLUSIONS: ACA bypass techniques continue to evolve with the addition of several variations. These variations push bypass techniques beyond the standard constructs and add important alternatives to our bypass arsenal.

Giant Serpentine Distal Anterior Cerebral Artery Aneurysm Treated with In Situ Side-to-Side A3-A3 Anastomosis and Aneurysm Resection.

BACKGROUND: Giant serpentine aneurysms that occur in the distal anterior cerebral artery are extremely rare and challenging to manage because of their complex structure. In this case, we show an aneurysm resection performed after in situ side-to-side A3-A3 bypass to treat a giant serpentine distal anterior cerebral artery aneurysm. CASE DESCRIPTION: Here, we present the case of a 55-year-old man with a giant distal anterior cerebral artery serpentine aneurysm who presented with severe headache and progressive unconsciousness. Computed tomography and cerebral angiography revealed a giant serpentine aneurysm in the right A2 segment. Both the right pericallosal and callosal marginal arteries branched from the outflow tract. To relieve the mass effect and preserve distal blood flow, an in situ side-to-side A3-A3 anastomosis and a partial aneurysm resection were performed sequentially. Postoperative cerebral angiography revealed no aneurysm blood filling and good perfusion in both anterior cerebral artery territories. CONCLUSIONS: Anterior cerebral artery giant serpentine aneurysms are rare and usually present with headache and mass effect. Aneurysm resection and distal flow protection are issues that we must consider. The sequential procedure of anastomosis and aneurysm resection is a feasible and safe option.

Combined Internal Maxillary Artery to Middle Cerebral Artery and In Situ Middle Cerebral to Middle Cerebral Artery Bypass for Complex Middle Cerebral Artery Aneurysm: 3-Dimensional Operative Video.

Flow-replacement revascularization and/or flow augmentation surgery may be necessary for safe deconstruction of complex middle cerebral artery (MCA) aneurysms. Roughly 1% to 2% of all MCA aneurysms have angiographic features prohibiting standard microsurgical or endovascular management. Consent was obtained from the patient for the production of this video. No International Review Board approval was required for the creation of this video. A 17-yr-old female presented at the age of 15 with headaches. At the time of initial presentation, the patient was found to have an MCA bifurcation aneurysm. Initially, the aneurysm was managed conservatively and followed. However, on follow-up imaging, the aneurysm was found to have grown and developed into a large, complex MCA bifurcation aneurysm. Patient underwent planned trapping and deconstruction of the aneurysm. An internal maxillary artery (IMAX) to MCA bypass was performed using a cephalic vein graph to a robust inferior MCA branch combined with an in Situ MCA to MCA bypass. Follow-up angiography showed complete occlusion of the aneurysm. Patient was neurologically intact at 1-yr follow-up. Microsurgery continues to be the best treatment option for complex MCA aneurysms. A surgeon trained in bypass is an absolute prerequisite for management of those lesions. The IMAX offers an ideal high flow donor vessel for subcranial to intracranial flow replacement, which was required for re-establishment of flow to the robust inferior MCA branch in this case. The superior branch of the MCA was less robust. Therefore, by recreating a more distal bifurcation, the in Situ side-to-side MCA-MCA bypass simplified the revascularization strategy.

Orphaned Middle Cerebral Artery Side-to-Side In Situ Bypass as a Favorable Alternative Approach for Complex Middle Cerebral Artery Aneurysm Treatment: A Case Series.

OBJECTIVE: Middle cerebral artery (MCA) aneurysms have continued to be primarily managed microsurgically. In cases of complex MCA aneurysms, revascularization could facilitate effective aneurysm treatment. The MCA candelabra provides excellent candidates for in situ side-to-side bypass. In the present case series, we have described applications of MCA in situ side-to-side bypass for the management of complex MCA aneurysms, along with a review of the pertinent data. METHODS: A retrospective review of a prospectively maintained neurosurgical patient database was performed to identify all patients treated with MCA side-to-side in situ bypass. Six consecutive patients were identified and included in the present series, representing a single-surgeon experience from February 2016 to November 2018. RESULTS: Of the 6 complex MCA aneurysms, all were unruptured, and one half had been treated via a minipterional approach that also allowed for simultaneous anterior communicating artery aneurysm clipping in 1 case. The median temporary occlusion time for anastomosis was 33 minutes (interquartile range [IQR], 30.3-35 minutes). Bypass patency was confirmed in all cases both intraoperatively and postoperatively. The median hospitalization time was 4.5 days (IQR, 2-8 days). The median follow-up period was 5.5 months (IQR, 2.8-22.3 months). All patients had achieved excellent or good (≤1) modified Rankin scale scores at discharge and during the follow-up period. No mortalities occurred, and no technical, bypass-related, or ischemic morbidities had developed. CONCLUSIONS: Our experience with MCA side-to-side in situ bypass has demonstrated its safety and utility in complex MCA aneurysm management. The favorable anatomy of the MCA branches allows for minimally invasive revascularization and clipping that can potentially reduce the hospitalization time and incidence of perioperative morbidity.

Posterior Cerebral Artery Reconstruction by In-Situ Bypass with Superior Cerebellar Artery via Occipital Transtentorial Approach.

BACKGROUND: Posterior cerebral artery (PCA) aneurysms are relatively rare, and neck clipping is often difficult due to their fusiform shape. We report a case of a thrombosed aneurysm of the distal PCA for which curative trapping and parent artery reconstruction by in situ bypass were performed through an occipital transtentorial approach (OTA). CASE DESCRIPTION: A 67-year-old woman had been suffering from numbness in the right face and limbs for 4 months. Radiologic imaging demonstrated a thrombosed aneurysm on a distal portion of the left PCA. Curative trapping of the aneurysm and in-situ bypass between the distal PCA and superior cerebellar artery were performed through the OTA. Before surgery, we had evaluated access to the PCA and feasibility of the bypass in a cadaveric simulation. The PCA was well exposed in the posterior half of the ambient cistern, and the proximity of the distal PCA to the superior cerebellar artery through a tentorial incision was confirmed. CONCLUSIONS: This OTA could represent a useful option for definitive treatment of distal PCA aneurysms.

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.

The In Situ Side-To-Side Bypass Technique: A Comprehensive Review of the Technical Characteristics, Current Anastomosis Approaches, and Surgical Experience.

OBJECTIVE: In situ side-to-side (STS) revascularization is an intracranial-intracranial bypass technique that is increasingly used to treat complex aneurysms and cerebral ischemia. This sophisticated technique involves connecting 2 proximal parallel vessels to create an artificial conduit for blood flow. This study aims to provide a detailed description of the configuration of the STS bypass technique and extensive information regarding its technical characteristics, current anastomosis approaches, and surgical significance. METHODS: A literature search was performed using the PubMed, Medline, ScienceDirect, Embase, Wiley Online Library, Cambridge Journals, SAGE Journals, Oxford Journals, Research Gate, and Google Scholar databases. The terms "intracranial-intracranial bypass," "in situ bypass," "communicating bypass," and "STS anastomosis" were searched to identify pertinent articles. Articles involving in situ STS anastomosis combined with other bypass methods were excluded. Computer tablet-drawn illustrations of this technique are provided to enhance comprehension. RESULTS: In total, 70 articles that met our search and inclusion criteria were identified. Overall, the radiographic and clinical outcomes of 132 (125 aneurysms and 7 cerebral ischemias) patients who underwent in situ STS revascularization were analyzed. CONCLUSIONS: Intracranial-intracranial bypass in the STS fashion can be a safe and effective strategy for the management of complex intracranial aneurysms and cerebral ischemia and is particularly attractive in rescue, anticipated, and troubleshooting cases. Despite its extreme rarity, a de novo aneurysm may be observed after STS anastomosis; thus, long-term follow-up is mandatory. Vascular neurosurgeons should consider including this procedure in their treatment armamentarium.

Microsurgical Bypass Training Rat Model: Part 2-Anastomosis Configurations.

BACKGROUND: Mastery of microsurgical anastomosis is key to achieving good outcomes in cerebrovascular bypass procedures. Animal models (especially rodents) provide an optimal preclinical bypass training platform. However, the existing models for practicing different anastomosis configurations have several limitations. OBJECTIVE: We sought to optimize the use of the rat's abdominal aorta and common iliac arteries (CIA) for practicing the 3 main anastomosis configurations commonly used in cerebrovascular surgery. METHODS: Thirteen male Sprague-Dawley rats underwent inhalant anesthesia. The abdominal aorta and the CIAs were exposed. The distances between the major branches of the aorta were measured to find the optimal location for an end-to-end anastomosis. Also, the feasibility of performing side-to-side and end-to-side anastomoses between the CIAs was assessed. RESULTS: All bypass configurations could be performed between the left renal artery and the CIA bifurcation. The longest segments of the aorta without major branches were 1) between the left renal and left iliolumbar arteries (16.9 mm ± 4.6), and 2) between the right iliolumbar artery and the aortic bifurcation (9.7 mm ± 4.7). The CIAs could be juxtaposed for an average length of 7.6 mm ± 1.3, for a side-to-side anastomosis. The left CIA could be successfully reimplanted on to the right CIA at an average distance of 9.1 mm ± 1.6 from the aortic bifurcation. CONCLUSIONS: Our results show that rat's abdominal aorta and CIAs may be effectively used for all the anastomosis configurations used in cerebral revascularization procedures. We also provide technical nuances and anatomic descriptions to plan for practicing each bypass configuration.