Preclinical Feasibility and Patency Analyses of a New Distal Coronary Connector: The ELANA Heart Bypass.

OBJECTIVE: This preclinical study determines the feasibility and 6-month patency rates of a new distal coronary connector, the Excimer Laser Assisted Nonocclusive Anastomosis (ELANA) Heart Bypass. METHODS: Twenty Dutch Landrace pigs received either a hand-sewn (n = 8) or an ELANA (n = 12) left internal thoracic artery to left anterior descending artery anastomosis, using off-pump coronary artery bypass grafting. Six-month patency rates were demonstrated by coronary angiography and histological evaluation. Throughout, procedural details and complication rates were collected. RESULTS: The ELANA Heart Bypass demonstrated 0% mortality and complication rates during follow-up. It was demonstrated feasible, with comparable perioperative flow measurements (ELANA vs hand-sewn, median [min to max], 24 [14 to 28] vs 17 [12 to 31] mL/min; P = 0.601) and fast construction times (3 [3 to 7] vs 31 [26 to 37] min; P < 0.001). Yet, an extra hemostatic stitch was needed in 25% of the ELANA versus 12.5% of the hand-sewn anastomoses. The 6-month patency rate of the ELANA Heart Bypass was 83.3% versus 100% in hand-sewn anastomoses. The 2 occluded ELANA-anastomoses were defined model-based errors. CONCLUSIONS: The ELANA Heart Bypass facilitates a sutureless distal coronary anastomosis. A design change is suggested to improve hemostasis and will be evaluated in future translational studies. This new technique is a potential alternative to hand-sewn anastomoses in (minimally invasive) coronary surgery.

Evaluation of a novel laser-assisted coronary anastomotic connector - the Trinity Clip - in a porcine off-pump bypass model.

To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e., occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated.

The nonocclusive laser-assisted coronary anastomotic connector in an off-pump porcine bypass model.

OBJECTIVES: To facilitate minimally invasive coronary artery bypass grafting, a simplified alternative for hand-sutured anastomoses must be developed. We assessed the feasibility and anastomotic healing of the ameliorated Excimer laser-assisted nonocclusive anastomosis coronary prototype connector in an acute rabbit study (study 1) and in a long-term porcine off-pump coronary bypass study (study 2). METHODS: Eighteen anastomoses were constructed on the abdominal aorta of the rabbit. In the porcine model, 15 left internal thoracic artery to left anterior descending coronary artery bypasses were evaluated intraoperatively and at 4 hours, 4 and 10 days, 2, 3, and 5 weeks, and 6 months (each n = 2 anastomoses). The anastomoses were examined by angiography, flow measurements, fractional flow reserve, coronary flow reserve, histologic features, and scanning electron microscopy. RESULTS: In study 1, all 18 anastomoses were patent and resisted supraphysiologic pressures (n = 12, 300 mm Hg). In study 2, the connector enabled nonocclusive and fast (7.7 ± 2.2 minutes, mean ± standard deviation) anastomosis construction. All but 1 of 15 anastomoses (owing to a technical error) were fully patent (FitzGibbon grade A) at follow-up. Histologic examination and scanning electron microscopy demonstrated complete endothelialization of the anastomoses at 10 days. At 6 months, no flow-limiting but streamline-covering intimal hyperplasia was shown (fractional flow reserve, 0.93 ± 0.07 mean ± standard deviation). CONCLUSIONS: The new nonocclusive coronary connector is easy to use, and the long-term results suggest favorable healing and remodeling in the porcine model. After downsizing, this anastomotic device, with its emphasis on zero ischemia and simplified prebounding of vessel walls, has intrinsic potential for minimally invasive off-pump coronary artery bypass surgery.

A new nonocclusive laser-assisted coronary anastomotic connector in a rabbit model.

OBJECTIVE: The Excimer laser-assisted nonocclusive anastomotic technique is a nonocclusive, facilitated bypass technique that is currently Conformité Européenne and Food and Drug Administration approved for clinical application in neurosurgery. In the present study, we assessed the safety and feasibility of a newly developed Excimer laser-assisted nonocclusive anastomosis-based prototype coronary anastomotic connector in an acute rabbit abdominal aortic bypass model before application in experimental coronary bypass surgery. In addition, 2 sealants were tested to facilitate anastomotic hemostasis in the current device prototype. METHODS: A total of 40 anastomoses were constructed on the abdominal aorta (3.5 mm outer diameter) of 10 rabbits. The anastomotic circumference was sealed by a surgical sealant to obtain complete hemostasis (BioGlue vs TachoSil). The anastomoses were evaluated by flow measurements construction time, hemostasis, histologic analysis, and burst pressure testing. RESULTS: The connector enabled a nonocclusive and fast (6.0 ± 1.7 minutes, mean ± SD [including sealing]) anastomosis construction and complete hemostasis in 95% (35/37). Sealing with BioGlue was faster than with TachoSil (19% vs 53% of construction time). Despite technical imperfections (7/40 failures to completely retrieve the flap by the laser), all 40 anastomoses were patent, showed reproducible construction with intima-adventitia apposition, streamlining thrombus coverage of the intraluminal laser rim, and no vessel wall damage. All anastomoses resisted ex vivo supraphysiologic pressures (> 300 mm Hg). CONCLUSIONS: The results of the present study have demonstrated that the Excimer laser-assisted nonocclusive anastomotic connector is safe and reliable and can be efficiently applied in an acute rabbit abdominal aortic bypass model. Provided the limitations can be addressed, this easy-to-use and nonocclusive technique has the potential to facilitate minimally invasive coronary bypass surgery.

The acute effect of increased laser energy during the excimer laser-assisted non-occlusive anastomosis procedure on the vessel wall of the recipient artery: a histopathological study.

BACKGROUND AND OBJECTIVE: The excimer laser-assisted non-occlusive anastomosis (ELANA) technique is a way of making an anastomosis of vessels without temporal occlusion that is used for cerebral revascularization. Currently, 10 mJ of laser energy is used during the ELANA procedure. We have recently demonstrated that increasing the laser energy may increase flap retrieval rate. The aim of the present study was to study the acute effect of increased laser energy during the ELANA procedure on the recipient vessel wall. MATERIALS AND METHODS: The ELANA technique was performed on the abdominal aortas of rabbits under anesthesia using three categories of laser energy (two laser episodes of 10, 13, and 15 mJ, respectively). The rabbits were subsequently sacrificed and the anastomoses were removed. A non-lased rabbit aorta was used as control. Recipient arteries were studied using histopathology and transmission electron microscopy. RESULTS: In all three categories of laser energy and in the control group, the tunica media and adventitia adjacent to the anastomosis were intact, apart from damage caused by sutures. In the control group, the endothelium was fully intact. In the 10 and 13 mJ subgroups, the endothelium was mostly intact [92% (range 85-98) and 87% (range 80-90) for 10 and 13 mJ, respectively]. In the 15 mJ subgroup, most of the endothelium was absent [32% (range 20-40) of endothelium intact], predominantly at the side opposed to the anastomosis. CONCLUSION: Increasing the laser energy during the ELANA procedure from 10 to 13 mJ does not cause additional acute damage to the vessel wall. Increasing the laser energy from 13 to 15 mJ results in increased acute damage of the endothelium, whereas tunica media and adventitia remain unaffected. Further studies are required to assess the long-term effects of increased laser energy during the ELANA technique.

Giant aneurysm clipping under protection of an excimer laser-assisted non-occlusive anastomosis bypass.

OBJECTIVE: To define the safety and clinical value of giant aneurysm clipping under protection of an excimer laser-assisted non-occlusive anastomosis (ELANA) bypass. METHODS: We report 32 patients with an uncoilable intracerebral giant aneurysm, operated on with the aid of an ELANA protective bypass between January 1, 1994, and January 1, 2008. We retrospectively collected data from patient records. Follow-up data were updated by telephone interview. We defined a favorable outcome as a successfully treated aneurysm and a better or equal postoperative modified Rankin scale (mRS) score compared with the preoperative mRS. RESULTS: In total 33 bypasses were constructed, of which 31 (94%) were patent during the rest of the procedure. The first failed bypass was salvaged during a second procedure. Of the second failed bypass, the ELANA anastomosis could be reused during second bypass surgery. All 32 aneurysms could be treated. The bypasses served as protection during temporary parent vessel occlusion (n = 24, 75%), control during aneurysm rupture (n = 3, 9%), and in all patients as an indicator for recipient artery narrowing during clip placement. Four bypasses (12%) eventually had to partially (n = 3) or fully (n = 1) replace recipient artery flow at the end of surgery. Postoperatively, 3 patients (9%) had a hemorrhagic complication and 2 patients (6%) had an ischemic complication. At long-term follow-up (mean, 6.1 +/- 3.4 y), 28 patients (88%) had a favorable functional outcome. CONCLUSION: The ELANA protective bypass is a safe and useful instrument for the treatment of these difficult aneurysms.

Predictors of patency of excimer laser-assisted nonocclusive extracranial-to-intracranial bypasses.

OBJECT: Excimer laser-assisted nonocclusive anastomosis (ELANA) is a technique that can be used for extracranial-to-intracranial (EC-IC) bypasses, without the necessity of temporary occlusion of the donor or recipient artery. Information on predictors of patency of EC-IC bypasses in general and the ELANA bypass in particular is sparse. The authors studied 159 ELANA EC-IC bypasses to find predictors of patency. METHODS: From a prospective database of patients who underwent EC-IC bypass surgery, 143 consecutive patients who underwent a total of 159 ELANA bypasses were studied. The associations of patient characteristics, surgical aspects, and technical aspects specific to the ELANA technique with intraoperative and postoperative bypass patency were studied using logistic regression analysis. RESULTS: At the end of the operation, 146 (92%) of the 159 bypasses were patent. A first attempt to create a bypass was almost 8 times more likely (OR 7.6, 95% CI 2.1-27.5; p = 0.02) to result in a patent bypass than a second attempt. Administration of a small amount of heparin during the operation was also associated with bypass patency (OR 5.2, 95% CI 1.1-24.9; p = 0.04). One hundred twenty-three (77%) of the 159 bypasses were functional at patency assessments during the 1st month after the operation. Older age (OR 1.043 for every year of increase in age, 95% CI 1.010-1.076; p = 0.01), male sex (OR 2.9, 95% CI 1.3-6.5; p = 0.01), and high intraoperative bypass flow (OR 1.017 for every milliliter per minute increase in flow, 95% CI 1.004-1.030; p = 0.01) were associated with postoperative bypass patency. CONCLUSIONS: Attempts to create a second EC-IC ELANA bypass after the first one are more likely to fail, whereas administration of heparin to the patient during the procedure increases the intraoperative bypass patency rate. Postoperative patency results are better in male and in older patients. Intraoperative bypass flow measurements are essential because high bypass flow is an important determinant of postoperative patency.

The impact of workflow and volumetric feedback on frameless image-guided neurosurgery.

OBJECTIVE: During image-guided neurosurgery, if the surgeon is not fully orientated to the surgical position, he or she will briefly shift attention toward the visualization interface of an image guidance station, receiving only momentary "point-in-space" information. The aim of this study was to develop a novel visual interface for neuronavigation during brain tumor surgery, enabling intraoperative feedback on the entire progress of surgery relative to the anatomy of the brain and its pathology, regardless of the interval at which the surgeon chooses to look. METHODS: New software written in Java (Sun Microsystems, Inc., Santa Clara, CA) was developed to visualize the cumulative recorded instrument positions intraoperatively. This allowed surgeons to see all previous instrument positions during the elapsed surgery. This new interactive interface was then used in 17 frameless image-guided neurosurgical procedures. The purpose of the first 11 cases was to obtain clinical experience with this new interface. In these cases, workflow and volumetric feedback (WVF) were available at the surgeons' discretion (Protocol A). In the next 6 cases, WVF was provided only after a complete resection was claimed (Protocol B). RESULTS: With the novel interactive interface, dynamics of surgical resection, displacement of cortical anatomy, and digitized functional data could be visualized intraoperatively. In the first group (Protocol A), surgeons expressed the view that WVF had affected their decision making and aided resection (10 of 11 cases). In 3 of 6 cases in the second group (Protocol B), tumor resections were extended after evaluation of WVF. By digitizing the cortical surface, an impression of the cortical shift could be acquired in all 17 cases. The maximal cortical shift measured 20 mm, but it typically varied between 0 and 10 mm. CONCLUSION: Our first clinical results suggest that the embedding of WVF contributes to improvement of surgical awareness and tumor resection in image-guided neurosurgery in a swift and simple manner.

Treatment of giant middle cerebral artery aneurysms with a flow replacement bypass using the excimer laser-assisted nonocclusive anastomosis technique.

OBJECTIVE: To define the clinical value of the flow replacement bypass using the excimer laser-assisted nonocclusive anastomosis (ELANA) technique in the treatment of patients with a noncoilable, nonclippable giant intracranial aneurysm of the middle cerebral artery (MCA). METHODS: Between 1999 and 2006, 22 patients with a giant intracranial aneurysm of the MCA were treated in our hospital with an ELANA flow replacement bypass and MCA occlusion. We collected data on patient characteristics, operative aspects, complications, and functional health scores using the modified Rankin Scale. Mean follow-up was 3.6 years (range, 0.2-7.7 yr). RESULTS: We were able to construct a patent bypass in 20 (91%) of 22 patients. All 34 ELANA attempts resulted in a patent anastomosis with a strong backflow directly after ELANA catheter retraction. The patients did not need to undergo temporary occlusion in any of the ELANA constructions. Mean +/- standard deviation intracranial-to-intracranial bypass flow was 53 +/- 13 ml/min. MCA aneurysm treatment was attempted in all 20 patients who had a patent bypass and was successful in 19 of them. There was a fatal hemorrhagic complication in one patient (5%), a nonfatal hemorrhagic complication in three patients (14%), and a nonfatal ischemic complication in six patients (27%). At follow-up, 17 patients (77%) had a functionally favorable outcome (modified Rankin Scale score at follow-up was the same as or less than the preoperative modified Rankin Scale score). All of these patients were independent at follow-up (modified Rankin Scale score < or =2). CONCLUSION: This study demonstrates satisfactory results in the treatment of giant MCA aneurysms with an ELANA flow replacement bypass, considering the very grave natural history and treatment complexity of these lesions. The ELANA technique is a useful tool in the treatment armamentarium of the vascular neurosurgeon.

Treatment of giant and large internal carotid artery aneurysms with a high-flow replacement bypass using the excimer laser-assisted nonocclusive anastomosis technique.

OBJECTIVE: To define the clinical value of the high-flow replacement bypass using the excimer laser-assisted nonocclusive anastomosis technique in the treatment of patients with a noncoilable, nonclippable giant or large intracranial aneurysm of the internal carotid artery (ICA). METHODS: We studied 34 patients with a giant intracranial aneurysm of the ICA proximal to its bifurcation who were treated with an extracranial-intercranial high-flow replacement bypass in our hospital between 1999 and 2004. We retrospectively collected data for patient characteristics, operative aspects, complications, and functional health scores using the modified Rankin scale. Long-term data were updated by questionnaire and telephone survey. Mean long-term follow-up period was 3.3 years (range, 0.6-5.6 yr). RESULTS: We were able to construct a patent bypass in 33 out of 34 patients (97%). In six patients (17%), we needed two bypass attempts. In one patient (3%), the bypass was technically impossible. After bypass construction, we occluded the ICA during or after surgery in 32 patients (94%), causing aneurysm thrombosis in all of these patients. A fatal complication occurred in two patients (6%) before we could occlude the ICA. A nonfatal complication occurred in seven patients (21%). In the long term, 25 patients (74%) had a favorable outcome and 27 patients (79%) were independent (modified Rankin scale, <3). CONCLUSION: This study shows that the excimer laser-assisted nonocclusive anastomosis high-flow replacement bypass, which provides maximum brain protection because of its nonocclusive character, is a reliable and effective method to treat these otherwise untreatable patients.

Sutureless nonocclusive bypass surgery in combination with an expanded polytetrafluoroethylene graft. Laboratory investigation.

OBJECT: Cerebral aneurysms that cannot be treated by clip or coil placement can be treated with high-flow bypass surgery using techniques such as the excimer laser-assisted nonocclusive anastomosis (ELANA). To simplify the technique, a sutureless ELANA (SELANA) was developed in combination with an expanded polytetrafluoroethylene (ePTFE) graft. METHODS: In 18 rabbits a bypass was constructed on the abdominal aorta using the SELANA technique with an ePTFE graft, resulting in 18 bypasses and 36 anastomoses. Short-term effects were analyzed in the first 2 weeks and at 2 and 3 months after the procedure. Patency was evaluated using quantitative ultrasound flowmetry. The anastomotic sites were studied using scanning electron microscopy. RESULTS: Construction of the bypass using the SELANA technique was easier and faster (15-25 minutes) compared with bypasses made with the ELANA technique (> 90 minutes). At the end of follow-up, 16 of 18 bypasses were patent. Of 36 SELANA anastomoses, 32 could be completed without short temporary occlusion of the recipient vessel. Scanning electron microscopy showed complete coverage of all anastomoses with neointimal repair tissue after 10 days. CONCLUSIONS: The SELANA technique provides further advantages over the conventional ELANA technique in ease of use and shortening of procedure time. The patency rate in this series was 89% and neointima repair tissue at the anastomosis site was complete after 10 days. Further experimental studies of the long-term patency and safety of this technique are necessary before clinical application.

Application accuracy in frameless image-guided neurosurgery: a comparison study of three patient-to-image registration methods.

OBJECT: The aim of this study was to compare three patient-to-image registration methods in frameless stereotaxy in terms of their application accuracy (the accuracy with which the position of a target can be determined intraoperatively). In frameless stereotaxy, imaging information is transposed to the surgical field to show the spatial position of a localizer or surgical instrument. The mathematical relationship between the image volume and the surgical working space is calculated using a rigid body transformation algorithm, based on point-pair matching or surface matching. METHODS: Fifty patients who were scheduled to undergo a frameless image-guided neurosurgical procedure were included in the study. Prior to surgery, the patients underwent either computerized tomography (CT) scanning or magnetic resonance (MR) imaging with widely distributed adhesive fiducial markers on the scalp. An extra fiducial marker was placed on the head as a target, as near as possible to the intracranial lesion. Prior to each surgical procedure, an optical tracking system was used to perform three separate patient-to-image registration procedures, using anatomical landmarks, adhesive markers, or surface matching. Subsequent to each registration, the target registration error (TRE), defined as the Euclidean distance between the image space coordinates and world space coordinates of the target marker, was determined. Independent of target location or imaging modality, mean application accuracy (+/- standard deviation) was 2.49 +/- 1.07 mm when using adhesive markers. Using the other two registration strategies, mean TREs were significantly larger (surface matching, 5.03 +/- 2.30 mm; anatomical landmarks, 4.97 +/- 2.29 mm; p < 0.001 for both). CONCLUSIONS: The results of this study show that skin adhesive fiducial marker registration is the most accurate noninvasive registration method. When images from an earlier study are to be used and accuracy may be slightly compromised, anatomical landmarks and surface matching are equally accurate alternatives.

Expanded polytetrafluoroethylene graft for bypass surgery using the excimer laser-assisted nonocclusive anastomosis technique.

OBJECT: Patients with complex craniocerebral pathophysiologies such as giant cerebral aneurysms, skull base tumors, and/or carotid artery occlusive disease are candidates for a revascularization procedure to augment or preserve cerebral blood flow. However, the brain is susceptible to ischemia, and therefore the excimer laser-assisted nonocclusive anastomosis (ELANA) technique has been developed to overcome temporary occlusion. Harvesting autologous vessels of reasonable quality, which is necessary for this technique, may at times be problematic or impossible due to the underlying systemic vascular disease. The use of artificial vessels is therefore an alternative graft for revascularization. Note, however, that it is unknown to what degree these grafts are subject to occlusion using the ELANA anastomosis technique. Therefore, the authors studied the ELANA technique in combination with an expanded polytetrafluoroethylene (ePTFE) graft. METHODS: The experimental surgeries involved bypassing the abdominal aorta in the rabbit. Ten rabbits were subjected to operations representing 20 ePTFE graft-ELANA end-to-side anastomoses. Intraoperative blood flow, followup angiograms, and long-term histological characteristics were assessed 75, 125, and 180 days postoperatively. Angiography results proved long-term patency of ePTFE grafts in all animals at all time points studied. Data from the histological analysis showed minimal intimal reaction at the anastomosis site up to 180 days postoperatively. Endothelialization of the ePTFE graft was progressive over time. CONCLUSIONS: The ELANA technique in combination with the ePTFE graft seems to have favorable attributes for end-to-side anastomoses and may be suitable for bypass procedures.

Treatment of giant and large internal carotid artery aneurysms with a high-flow replacement bypass using the excimer laser-assisted nonocclusive anastomosis technique.

OBJECTIVE: To define the clinical value of the high-flow replacement bypass using the excimer laser-assisted nonocclusive anastomosis technique in the treatment of patients with a noncoilable, nonclippable giant or large intracranial aneurysm of the internal carotid artery (ICA). METHODS: We studied 34 patients with a giant intracranial aneurysm of the ICA proximal to its bifurcation who were treated with an extracranial-intercranial high-flow replacement bypass in our hospital between 1999 and 2004. We retrospectively collected data for patient characteristics, operative aspects, complications, and functional health scores using the modified Rankin scale. Long-term data were updated by questionnaire and telephone survey. Mean long-term follow-up period was 3.3 years (range, 0.6-5.6 yr). RESULTS: We were able to construct a patent bypass in 33 out of 34 patients (97%). In six patients (17%), we needed two bypass attempts. In one patient (3%), the bypass was technically impossible. After bypass construction, we occluded the ICA during or after surgery in 32 patients (94%), causing aneurysm thrombosis in all of these patients. A fatal complication occurred in two patients (6%) before we could occlude the ICA. A nonfatal complication occurred in seven patients (21%). In the long term, 25 patients (74%) had a favorable outcome and 27 patients (79%) were independent (modified Rankin scale, <3). CONCLUSION: This study shows that the excimer laser-assisted nonocclusive anastomosis high-flow replacement bypass, which provides maximum brain protection because of its nonocclusive character, is a reliable and effective method to treat these otherwise untreatable patients.

The excimer laser-assisted nonocclusive anastomosis practice model: development and application of a tool for practicing microvascular anastomosis techniques.

OBJECTIVE: To practice microsurgical skills, several experimental models are available that diminish the need for experimental animals. We defined criteria with which such models should comply, and we tested whether the models described in literature, as well as our own practice model, comply with these criteria. METHODS: We defined the criteria to which these models should comply, and we performed a literature search on microvascular practice models. During the development of the Excimer laser-assisted nonocclusive anastomosis technique, we designed our own Excimer laser-assisted nonocclusive anastomosis Practice Model (EPM) according to those criteria, and we compared that model with the models described in the literature. RESULTS: All practice models could be categorized into three groups: beginner, moderate, and advanced. Our EPM complies with almost all criteria defined in the beginner and moderate groups and has much in common with the models that are categorized in the advanced group. CONCLUSION: In consideration of the methods to learn microvascular surgical techniques, the EPM can be used for a very long time before the need for living animals arises. This last aspect remains an inescapable condition for practicing microsurgical skills. However, with use of the EPM or another practice model, the amount of experimental animals can be drastically reduced.

Long-term reendothelialization of excimer laser-assisted nonocclusive anastomoses compared with conventionally sutured anastomoses in pigs.

OBJECT: In contrast to conventional anastomosis methods, the excimer laser-assisted nonocclusive anastomosis (ELANA) technique involves a platinum ring and intima-adventitia apposition with a rim of medial and adventitial layers exposed to the bloodstream. The authors assessed the reendothelialization of porcine carotid arteries through ELANA compared with conventional anastomosis by using scanning electron microscopy. METHODS: In 28 pigs a bypass with one ELANA and one conventional anastomosis was made on the left common carotid artery. All patent anastomoses were evaluated intraoperatively with the aid of an ultrasonographic flowmeter and postoperatively by using scanning electron microscopy at 2 weeks, 2 months, 3 months, and 6 months thereafter. Twenty-four of 28 bypasses (48 of 56 end-to-side anastomoses) were fully patent at the time of evaluation. On scanning electron microscopic evaluation of the bypasses, all 48 patent anastomoses showed complete reendothelialization, including all 24 ELANAs in which the endothelium covered the rim and the laser-ablated edge completely. No endothelial difference was observed between conventional anastomoses and ELANAs, aside from the obvious anatomical differences like the platinum ring, which had been completely covered with endothelium. At 6 months postsurgery, remodeling of the ELANA was observed, leaving the ring covered with a layer of endothelium as the most narrow part of the anastomosis. CONCLUSIONS: In long-term experiments, ELANA allows reendothelialization comparable to that achieved with conventional anastomosis. Considering its nonocclusive and high-flow characteristics, the ELANA technique is preferable in cerebral revascularization procedures.

Excimer laser-assisted bypass in aneurysm treatment: short-term outcomes.

OBJECT: If clip application or coil placement for treatment of intracranial aneurysms is not feasible, the parent vessel can be occluded to induce thrombosis of the aneurysm. The Excimer laser-assisted anastomosis technique allows the construction of a high-flow bypass in patients who cannot tolerate such an occlusion. The authors assessed the complications of this procedure and clinical outcomes after the construction of high-flow bypasses in patients with intracranial aneurysms. METHODS: Data were retrospectively collected on patient and aneurysm characteristics, procedural complications, and functional outcomes in 77 patients in whom a high-flow bypass was constructed. Logistic regression analysis was used to quantify the relationships between patient and aneurysm characteristics on the one hand and outcome measures on the other. Fifty-one patients harbored a giant aneurysm, 24 patients suffered from a ruptured aneurysm, and 35 patients from an unruptured symptomatic aneurysm. In 22 patients (29%; 95% confidence interval [CI] 19-40%) a permanent deficit developed from an operative complication. At a median follow-up period of 2.5 months, 25 patients (32%; 95% CI 22-44%) were dependent or had died; in 10 of these patients (13% of all patients; 95% CI 6-23%) operative complications were the single cause of this poor outcome. Univariate analysis demonstrated that a poor clinical condition before treatment (odds ratio [OR] 4.7; 95% CI 1.7-13.3) and a history of cardiovascular disease (OR 4.1; 95% CI 1-16.2) increased the risk of poor outcome. Multivariate analysis demonstrated that only the clinical condition before treatment was significantly related to outcome (OR 4; 95% CI 1.3-11.9). CONCLUSIONS: In patients with an intracranial aneurysm that cannot be treated by clip application or coil placement, and in whom occlusion of the parent artery cannot be tolerated, the construction of a high-flow bypass should be considered. This procedure carries a considerable risk of complications, but this should be weighed against the disabling or life-threatening effects of compression, the high risk of rupture, and the substantial chance of poor outcome after the rupture of such aneurysms.

Effectiveness of neurosurgical clip application in patients with aneurysmal subarachnoid hemorrhage.

OBJECT: Neurosurgical clip application is the standard method used to prevent rebleeding in patients with aneurysmal subarachnoid hemorrhage (SAH). The authors assessed the magnitude of the reduction in poor outcomes that accompanies a strategy aimed at surgery. METHODS: Three hundred forty-six consecutive patients with aneurysmal SAH were studied. The authors estimated the number of surgically treated patients with good outcomes who would have had poor outcomes as a consequence of rebleeding if clip application had not been performed (A). They also assessed the number of patients whose poor outcomes were exclusively caused by operative complications (B). Without an operation some of these patients would have had poor outcomes because of rebleeding (C). The authors represented the number of patients in whom poor outcome was prevented by surgery with the following formula: A - B + C. They assessed the relationships between baseline characteristics of patients and aneurysms and the likelihood that a patient underwent surgery, the risk of operative complications, and the risk of rebleeding. The absolute reduction in the risk of poor outcome found in patients who undergo surgery was 9.7%. This implies that to prevent a poor outcome in one patient, surgery had to be performed in 10. The relative risk of poor outcome following surgery compared with that after conservative treatment was estimated to be 0.81. Logistic regression analysis showed a statistically significant relationship between patient age older than 65 years and the occurrence of operative complications (odds ratio [OR] 2.49; 95% confidence interval [CI] 1.03-6.03), between age older than 65 years and the likelihood of undergoing surgery (OR 0.12; 95% CI 0.07-0.2), and between a poor clinical condition at admission and the likelihood of undergoing surgery (OR 0.26; 95% CI 0.14-0.47). The authors did not identify any predictive factors for rebleeding when the Cox proportional hazard model was used. CONCLUSIONS: The beneficial effect of a treatment strategy in which the goal is surgery is substantial. If new treatment modalities such as embolization with coils are explored, these should carefully be compared with surgery before they are generally introduced.

Excimer laser-assisted high-flow extracranial/intracranial bypass in patients with symptomatic carotid artery occlusion at high risk of recurrent cerebral ischemia: safety and long-term outcome.

BACKGROUND AND PURPOSE: The goal of this study was to determine safety and long-term outcome of the excimer laser-assisted high-flow extracranial/intracranial (EC/IC) bypass in patients with symptomatic carotid artery occlusion (CAO) at high risk of recurrent stroke. METHODS: In a prospectively collected cohort of 103 patients with symptomatic CAO, 15 patients were selected for excimer laser-assisted EC/IC bypass surgery on the basis of predefined selection criteria: (1) transient or moderately disabling symptoms of focal cerebral ischemia, not symptoms of the retina only; (2) continuing symptoms after documentation of the CAO; (3) evidence of a possible hemodynamic origin of symptoms; and (4) informed consent of the patient. RESULTS: Eleven patients underwent the operation without complications One patient had a severely disabling stroke (Rankin grade 4) 11 days after the operation; the bypass was found occluded on reoperation. Two other patients had a moderately disabling stroke (Rankin grade 3) immediately after the operation. One patient died of myocardial infarction 1 day after surgery. Median follow-up time was 27 months. Of the 11 patients who underwent the operation without complications, 1 died 17 months after the operation of a brainstem stroke, and another patient had a new stroke ipsilateral to his CAO 10 months after the operation but without a change in Rankin grade. CONCLUSIONS: The excimer laser-assisted high-flow EC/IC bypass operation is a potentially promising procedure in patients with symptomatic CAO and a presumably high risk of recurrent stroke, but the procedure carries a definite risk. This risk is probably related not only to the procedure itself but also to the selection of patients.

Construction of a new posterior communicating artery in a patient with poor posterior fossa circulation: technical case report.

OBJECTIVE AND IMPORTANCE: The carotid and the vertebrobasilar circulation were connected, effectively creating a new posterior communicating artery (PComA). The excimer laser-assisted nonocclusive anastomosis technique is a new anastomosis technique whereby formerly untreatable patients may be treated with an intracranial artery-to-intracranial artery bypass procedure. This report is the first one in which an angiographically proved patent internal carotid artery-posterior cerebral artery segment P1 bypass is presented. CLINICAL PRESENTATION: Our patient presented with repeated episodes of vertebrobasilar ischemia because of vertebral artery occlusion and stenosis. INTERVENTION: An internal carotid artery-posterior cerebral artery segment P1 bypass procedure was performed. Because the patient experienced transient ischemia in the left cerebral hemisphere at the end of postoperative angiography procedure, no radiological intervention was performed, and the patient refused to undergo a new radiological intervention at a later stage. TECHNIQUES: Both anastomoses were made using the excimer laser-assisted nonocclusive anastomosis technique. CONCLUSION: Intraoperative flowmetry was performed using an ultrasound flowmeter, which disclosed blood flow of 35 ml/min through the bypass. We hope that this new PComA suffices to protect the patient from infarction in the territory of the vertebrobasilar circulation.