The Identification of Factors That Influence the Quality of Bypass Anastomosis and an Evaluation of the Usefulness of an Experimental Practical Scale in This Regard

BACKGROUND

Several factors associated with interrupted and continuous suturing techniques affect the quality of bypass anastomosis. It is difficult to determine the impact of these factors during surgery. The primary objective of this study was to evaluate factors with the potential to influence the quality of bypass anastomosis using either interrupted or continuous suturing. A secondary objective was to evaluate the usefulness of a practical scale when comparing interrupted and continuous suturing techniques to improve bypass anastomosis.

METHODS

Interrupted (n = 100) and continuous (n = 100) suturing techniques were used in 200 end-to-side bypasses to a depth of 3 cm and were assessed by 5 neurosurgeons.

RESULTS

Vessel closing time (P < 0.001), stitch distribution (P < 0.001), intima-intima attachment (P < 0.001), and size of the orifice (P < 0.001) had a significant impact on the quality of the bypass regardless of the suturing technique used. The suturing technique used (interrupted or continuous) and positioning of the recipient vessel (vertical or horizontal) did not significantly influence the quality of anastomosis. Using multivariate analysis, the highest statistical significance with regard to bypass quality was attributed to the large size of the orifice and intimal attachment.

CONCLUSIONS

There were advantages and disadvantages to both suturing techniques. The scale was a practical way to measure and improve performance.

The Identification of Factors That Influence the Quality of Bypass Anastomosis and an Evaluation of the Usefulness of an Experimental Practical Scale in This Regard

BACKGROUND

Several factors associated with interrupted and continuous suturing techniques affect the quality of bypass anastomosis. It is difficult to determine the impact of these factors during surgery. The primary objective of this study was to evaluate factors with the potential to influence the quality of bypass anastomosis using either interrupted or continuous suturing. A secondary objective was to evaluate the usefulness of a practical scale when comparing interrupted and continuous suturing techniques to improve bypass anastomosis.

METHODS

Interrupted (n = 100) and continuous (n = 100) suturing techniques were used in 200 end-to-side bypasses to a depth of 3 cm and were assessed by 5 neurosurgeons.

RESULTS

Vessel closing time (P < 0.001), stitch distribution (P < 0.001), intima-intima attachment (P < 0.001), and size of the orifice (P < 0.001) had a significant impact on the quality of the bypass regardless of the suturing technique used. The suturing technique used (interrupted or continuous) and positioning of the recipient vessel (vertical or horizontal) did not significantly influence the quality of anastomosis. Using multivariate analysis, the highest statistical significance with regard to bypass quality was attributed to the large size of the orifice and intimal attachment.

CONCLUSIONS

There were advantages and disadvantages to both suturing techniques. The scale was a practical way to measure and improve performance.

Developing practice recommendations for endovascular revascularization for acute ischemic stroke

Guidelines have been established for the management of acute ischemic stroke; however, specific recommendations for endovascular revascularization therapy are lacking. Burgeoning investigation of endovascular revascularization therapies for acute ischemic stroke, rapid device development, and a diverse training background of the providers performing the procedures underscore the need for practice recommendations. This review provides a concise summary of the Society of Vascular and Interventional Neurology endovascular acute ischemic stroke roundtable meeting. This document was developed to review current clinical efficacy of pharmacologic and mechanical revascularization therapy, selection criteria, periprocedure management, and endovascular time metrics and to highlight current practice patterns. It therefore provides an outline for the future development of multisociety guidelines and recommendations to improve patient selection, procedural management, and organizational strategies for revascularization therapies in acute ischemic stroke.

The adverse effects of flow-diverter stent-like devices on the flow pattern of saccular intracranial aneurysm models: computational fluid dynamics study

BACKGROUND

Stent deployment across the aneurysmal neck has been established as one of the endovascular methods to treat intracranial aneurysms with or without coils.

OBJECTIVE

The purpose is to study the possible adverse effects of deployment of the new flow-diverter stent-like devices (FD) on the flow characteristics of saccular aneurysm models.

METHODS

Numerical simulations of the blood flow patterns in the artificial models of three aneurysms were studied. One model was designed without an FD stent, the second model with one FD stent, and the third model with two stents. Numerical simulation for incompressible laminar blood flow was conducted in the three artificial cerebral aneurysm models by means of computational fluid dynamics.

RESULTS

There was a noticeable increase in the values of the circumferential pressure distributed on the walls of the aneurysm after stent deployment; this led to an increase the tension of the aneurysm surface and was considered to be an adverse effect. This pressure increase was further aggravated by the deployment of another stent. However, there is a beneficial effect of using FD stents, translating into the reduction of the flow velocity inside the aneurysm and wall shear stress at the inflow zone. This reduction decreases further with the deployment of another stent.

CONCLUSION

Aneurysms become tenser after the deployment of one flow-diverter stent and (more tense still) after after the deployment of another stent. This principle should be kept in mind when choosing which group of aneurysms is the best candidate for such a treatment strategy. This study recommends deploying several FD stents during endovascular procedures until complete arrest of the blood flow occurs during the procedure; otherwise, the aneurysm may become tenser and dangerous if a slow blood flow jet still exists inside it at the end of the procedure.

Radiographic and clinical predictors of hemodynamic insufficiency in patients with athero-occlusive disease

INTRODUCTION

Recent studies have shown that patients with increased oxygen extraction fraction (OEF) as measured by positron emission tomography (PET) have a substantially increased risk of stroke as a result of hemodynamic insufficiency. These patients appear to be ideal candidates for extracranial (EC)-intracranial (IC) bypass. The feasibility of this screening protocol, however, is controversial given PET's limited availability and high expense. A better understanding of the clinical factors that identify patients with potential hemodynamic insufficiency would streamline screening and improve cost-efficiency.

METHODS

We performed a MEDLINE (1985-2007) database search for studies identifying clinical and radiographic predictors of hemodynamic failure and increased OEF on PET. We used the following key words, singly and in combination: "EC-IC bypass," "hemodynamic failure," and "misery perfusion." Additional studies were identified manually by scrutinizing references from manuscripts, major neurosurgical journals and texts, and personal files. Each study was reviewed for methodology, clinical criteria, and correlation with subsequent PET findings and stroke rates. A consensus was determined regarding the predictive value of each marker.

RESULTS

Our literature search revealed 5 clinical and radiographic markers that have been used to identify patients with hemodynamic failure: orthostatic limb shaking, blurry vision on exposure to heat, leptomeningeal and ophthalmic collateral circulation on angiography, watershed infarction, and impaired vasodilatory response to acetazolamide. Orthostatic limb shaking is a rare finding but is predictive of hemodynamic failure and is associated with increased stroke risk. Blurry vision on exposure to heat is not predictive of increased stroke risk. Leptomeningeal and ophthalmic collateral circulation is a sensitive but not specific marker. Watershed infarction is highly sensitive and impaired vasodilatory response to acetazolamide is associated with increased OEF but may not be interchangeable.

CONCLUSIONS

Orthostatic limb shaking, watershed infarction, collateral circulation, and impaired vasoreactivity to acetazolamide in patients with athero-occlusive disease may predict hemodynamic failure, increased OEF on PET, and high stroke rates. Recognition of these predictive markers may improve patient selection for surgical intervention, as such individuals appear to benefit from EC-IC bypass.

Treatment strategy for giant aneurysms in the cavernous portion of the internal carotid artery

BACKGROUND

As direct surgery to treat giant aneurysms of the ICA is difficult, ICA occlusion is the conventional treatment in patients with BTO tolerance. To determine whether bypass surgery should be performed after carotid occlusion by trapping or proximal occlusion, we developed a treatment strategy that includes BTO and SPECT.

METHODS

We report 19 patients with symptomatic giant aneurysms in the cavernous portion of ICA. The appropriate type of bypass surgery was determined by the results of BTO and SPECT. The type of ICA occlusion selected was based on the evaluation of retrograde filling of the aneurysm during BTO.

RESULTS

In all 19 patients, the ICA was sacrificed; 10 patients also underwent bypass surgery (low-flow bypass with STA-MCA anastomosis, n = 7; medium-flow bypass with radial artery graft, n = 2; high-flow bypass with vein graft, n = 1). Coil trapping was performed in 11 patients; proximal occlusion in 8. In 18 patients, there were no ischemic complications after treatment; 1 patient who had been treated by proximal ICA occlusion developed transient ischemia due to an intra-aneurysmal thrombus. Cranial nerve palsies were improved in 16 patients.

CONCLUSIONS

Based on our experience, we recommend that patients with giant aneurysms in the cavernous portion of the ICA be evaluated by BTO and SPECT. In conjunction with bypass surgery, ICA trapping or proximal occlusion constitutes an effective treatment strategy.

Percutaneous angioplasty of a chronic total occlusion of the intracranial internal carotid artery. Case report

BACKGROUND

A CTO of the intracranial ICA is usually managed medically and rarely by EC-IC bypass in selected patients. Percutaneous transluminal angioplasty has not been used.

CASE DESCRIPTION

A 73-year-old man presented with frequent temporary blindness of the left eye and dizziness due to thrombotic occlusion of the left intracranial ICA, causing hemodynamic compromise. This patient was successfully treated by percutaneous angioplasty (balloon angioplasty and stent placement) under proximal balloon protection at 7 weeks from the ictus. Ischemic symptoms had not recurred during the 6-month follow-up period.

CONCLUSION

Percutaneous angioplasty for a CTO of the intracranial ICA is technically feasible and can be an alternative to EC-IC bypass in a selected group of patients with symptomatic hemodynamic compromise, which is refractory to the best medical treatment.

Magnetic resonance angiography evaluation of external carotid artery tributaries in moyamoya disease

BACKGROUND AND PURPOSE

High-resolution magnetic resonance (MR) image has been introduced to diagnose and follow-up moyamoya disease and visualized moyamoya vessels and internal carotid artery stenosis. This study was performed to assess the utility of MR angiography (MRA) for the evaluation of anastomotic channels through the external carotid artery (ECA) in moyamoya disease patients.

METHODS

Twenty patients with moyamoya disease were reviewed. The cortical anastomosis and superficial temporal artery (STA), middle meningeal artery, and deep temporal artery by MRA were evaluated and were compared with those by digital subtraction angiography if obtained. Fifteen patients (24 hemispheres) underwent bypass surgery, including encephaloduroarteriosynangiosis in 14 hemispheres and STA-middle cerebral artery anastomosis with encephalomyosinangiosis in 10 hemispheres. Five patients did not undergo any surgery.

RESULTS

MRA could show these vessels and the patency of anastomosis formed by the surgery and also showed naturally formed anastomosis and ECA tributaries in the patients who did not undergo any surgery.

CONCLUSION

MRA provides useful information for follow-up evaluation on the development of the ECA system in moyamoya disease.

Extracranial-intracranial arterial bypass for treatment of occlusion of the internal carotid artery

Extracranial-intracranial arterial bypass was frequently utilized in the 1970s and early 1980s to treat patients with atherosclerotic occlusive carotid arterial lesions not amenable to extracranial arterial revascularization procedures. After a large randomized trial reported in 1985 that there was no benefit of surgery in these patients, the procedure was generally abandoned as a treatment for symptomatic atherosclerotic cerebrovascular disease. In the past two decades, multiple studies have shown that patients with impaired cerebral hemodynamics distal to an occlusive cerebrovascular lesion have a significantly increased risk of subsequent stroke. Two new randomized, controlled clinical trials of extracranial-intracranial arterial bypass in patients with symptomatic atherosclerotic occlusive cerebrovascular disease that are using cerebral hemodynamic criteria for patient selection are currently in progress. At the present time, extracranial-intracranial arterial bypass should not be performed on these patients outside of a clinical trial.

Extracranial-intracranial bypass surgery in cerebrovascular diseases

Since the report from the International Study on extracranial-intracranial bypass was presented in 1985, an abrupt stop to almost all bypass surgery was introduced. The clear goals of the bypass study to reduce repeated strokes based on extracranial-intracranial bypass could not be documented. This review emphasizes the drawbacks of this previous study and why its conclusions were too sweeping, including statements that the study could not validate. The present status on cerebral hemodynamics and possible augmentations of reduced cerebral vascular reserve using extracranial-intracranial bypass are given. It is concluded that in hemodynamic proven cases extracranial-intracranial bypass may definitely benefit the patients. This group of patients, among all stroke victims in the International Study, could not be deducted due to the study design. The high frequency of repeated serious strokes occurring among patients with hemodynamic insufficiency and its prevention by bypass surgery is documented. The right operation was carried out among a large group of "wrong" patients. The prevention of repeated strokes that an extracranial-intracranial bypass allows us today, indicates that this operative method should also be possibly applied in the Kingdom under well defined hemodynamic circumstances.

Effects of bypass on CO2 cerebrovascular reactivity in ischaemic cerebrovascular diseases--based on the intra-operative LCBF and CO2 cerebrovascular reactivity studies

The authors evaluated the effects of superficial temporal to middle cerebral artery (STA-MCA) bypass on CO2 cerebrovascular reactivity (CVR) in ischaemic cerebrovascular diseases (CVDs). Local cerebral blood flow (LCBF) and CO2 CVR in 19 patients with ischaemic CVD subjected to standard STA-MCA bypasses were examined during surgery. Single photon emission computed tomography (SPECT) with acetazolamide (ACZ) activation was also performed before and at 1 month after surgery. The results are as follows. 1) Before bypass, the average CO2 CVR value was -1.50 +/- 2.30%/mmHg (mean +/- SD). SPECT showed disturbed response to ACZ in all cases. Fifteen cases showed the steal phenomenon. After bypass, the mean CO2 CVR value significantly (p < 0.05) increased, and four cases resolved their steal phenomenon. 2) Before bypass, the mean LCBF was significantly (p < 0.05) lower than the control level. After bypass, the mean LCBF significantly (p < 0.05) increased. 3) In the postoperative SPECT findings, 13 cases showed a disturbed response to ACZ. The CO2 CVR value in these 13 cases was -1.21 +/- 1.19%/mmHg, which was significantly (p < 0.05) low compared to the values for the 6 cases showing normal postoperative ACZ responses. In ischaemic CVDs before bypass, the CO2 CVR values were extremely low. After bypass, however, CO2 CVR and LCBF values significantly improved. SPECT findings, including ACZ challenge, correlated well to the LCBF and CO2 CVR values. STA-MCA by pass exerted a favourable effect on the CO2 CVR and LCBF values immediately after bypass in the cases showing a reduced pre-operative response to CO2.

Efficacy of direct revascularization in adult Moyamoya disease: haemodynamic evaluation by positron emission tomography

To evaluate the efficacy of direct cerebrovascular reconstruction to prevent intracranial bleeding from the point of view of haemodynamic status, we performed positron emission tomography (PET) studies in 5 adult patients with Moyamoya disease before and after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis. Regional cerebral blood flow (rCBF), regional cerebral metabolic rate of oxygen (rCMRO2) and regional oxygen extraction fraction (rOEF) in the MCA territories and regional cerebral blood volume (rCBV) in the striatum were measured before and after STA-MCA anastomosis. Correlation between the change of these PET parameters and post-operative decreased opacification of Moyamoya vessels were analyzed. Pre-operatively, significant elevation of rCBV were observed in the basal ganglia as well as significant reduction of rCBF and elevation of rOEF with reduction of rCMRO2 in the MCA territories, indicating "misery" perfusion in the cerebral hemisphere and blood pooling in the Moyamoya vessels under increased haemodynamic stress. Post-operative PET study showed improvement of misery perfusion and reduction of rCBV in the basal ganglia. Reduction of rCBV in the basal ganglia generally compatible with decreasing Moyamoya vessels on angiographic findings. Our results suggests that direct bypass surgery could have a potential both for decreasing haemodynamic stress on Moyamoya vessels and to improve misery perfusion in the hemisphere.

Profound hypothermia and circulatory arrest with skull base approaches for treatment of complex posterior circulation aneurysms

OBJECTIVE

Cardiopulmonary bypass with profound hypothermia and circulatory arrest has seen a resurgence as an adjunct technique in neurological surgery. We report our experience with this technique in treating seven complex vertebro-basilar aneurysms.

METHODS

Skull base approaches were used in all cases, providing excellent exposure and minimizing brain retraction. There were six basilar artery aneurysms and one giant fusiform vertebro-basilar artery aneurysm. All aneurysms but one had an apparent neck, which could be clipped. The fusiform vertebro-basilar artery aneurysm was trapped, partially resected, and the circulation was reestablished with a saphenous vein graft from the cervical internal carotid artery to the mid-basilar artery.

RESULTS

Five patients had an excellent outcome and two had a good outcome at one year or at latest follow up. Two of the patients showed improvement of neurological deficits which were present before the surgical intervention.

CONCLUSION

Applying very strict selection criteria in this small series of patients with posterior circulation aneurysms, excellent or good results were achieved using the profound hypothermic circulatory arrest technique.

Subclavian artery revascularization: a comparison between carotid-subclavian artery bypass and subclavian-carotid transposition

Extrathoracic revascularization has become the most popular form of surgical treatment of symptomatic subclavian disease. Despite the many theoretical advantages, subclavian-carotid transposition (SCT) has not gained wide popularity. During a 15-year period, 46 patients underwent carotid-subclavian bypass (CSB) or SCT for symptoms referable to occlusion of the subclavian artery. Follow-up ranged from 2 to 148 months (mean, 46.9 months). Seven-year actuarial patency rate was 100% for SCT and 86% +/- 7% for CSB (p = NS). Mean operative time and intraoperative blood loss were significantly reduced for SCT (p less than 0.05). After CSB a continuous deterioration of the hemodynamic status of the reconstruction was noted, whereas there were no significant changes after SCT (p less than 0.05). Whenever feasible, SCT should be considered the operation of choice for patients with symptomatic severe subclavian artery disease.

Surgery to prevent stroke. High hopes and deep disappointment

Carotid endarterectomy and EC/IC bypass grafting have been widely adopted for patients considered at risk from stroke, without good evidence of efficacy. Unjustified claims for surgery usually derive from overestimating the dangers of the disease without surgery, while perioperative risks are underestimated. Inadequate follow-up and choosing irrelevant outcome measures often add to the confusion. All these factors apply to surgery for stroke. A trial of EC/IC bypass in 1,377 patients from three continents took 8 years to complete and showed no benefit in patients randomized to surgery. Reluctance to accept this result led to detailed critiques of this trial in several journals, largely based on the discovery that many patients had been operated on in some centers without having been randomized. In reply, the investigators showed that these cases did not affect the "resounding negativity of the results." Lack of good data about the prognosis of patients with TIAs or minor strokes was the fundamental reason for so much misplaced surgical effort. This applies equally to carotid endarterectomy, for which large trials are currently being completed. Had there been a reliable data base of patients at risk of stroke, prospectively collected and followed, the efficacy of these two operations could have been determined much sooner, and inappropriate diffusion might have been prevented.

Extracranial-intracranial bypass surgery for the management of vasospasm after subarachnoid hemorrhage

A case is presented which demonstrates the potential utility of the extracranial-intracranial bypass procedure for the treatment of vasospasm after subarachnoid hemorrhage. Extracranial-intracranial bypass surgery offers another alternative to the treatment of patients with vasospasm who have failed aggressive medical management.

Dependency on bypass circulation: a case study

In a case of consecutive occlusion of both internal carotid arteries bilateral STA-MCA anastomoses were established. Since a series of angiographic examinations were undertaken, dynamics and probable efficacy of both natural and artificial collateral circulations could be followed up in a two-year period. Objectively in the evaluation of anastomoses was enhanced by direct percutaneous STA-angiography (STAG), in order to delineate the vascular territory irrigated exclusively by the anastomosis. By demonstrating exactly the functional capacity of anastomoses in correlation with the clinical course, dependency on bypass circulation could be assessed.