Residuals, recurrences and re-treatment after endovascular repair of intracranial aneurysms: A retrospective methodological comparison

OBJECTIVE

Incomplete aneurysm occlusions and re-treatment rates of 52 and 10-30%, respectively, have been reported following endovascular treatment of intracranial aneurysms, raising clinical concerns regarding procedural efficacy. We compare residual, recurrence and re-treatment rates subject to different endovascular techniques in both ruptured and unruptured intracranial aneurysms at a comprehensive state-wide tertiary neurovascular centre in Australia.

METHODS

Medical records, procedural and follow-up imaging studies of all patients who underwent endovascular treatment for intracranial aneurysms between July 2010 and July 2017 were reviewed retrospectively. Residuals, recurrences and re-treatment rates were assessed regarding initial aneurysm rupture status and applied endovascular technique: primary coiling, balloon- and stent-assisted coiling and flow diversion.

RESULTS

Among 233 aneurysms, residual, recurrence and re-treatment rates were 27, 11.2 and 9.4%, respectively. Compared with unruptured aneurysms, similar residual and recurrence (p > .05), but higher re-treatment rates (4.5% vs. 19%; p < .001) were found for ruptured aneurysms. Residual, recurrence and re-treatment rates were: 13.3, 16 and 12% for primary coiling; 12, 12 and 10.7% for balloon-assisted coiling; 14.9, 7.5 and 4.5% for stent-assisted coiling; 91.9, 0 and 5.4% for flow diversion. Stent-assistance and flow-diversion were associated with lower recurrence and re-treatment rates, when compared with primary- and balloon-assisted coiling (p < .05).

CONCLUSIONS

Residuals and recurrences after endovascular treatment of intracranial aneurysms are less common than previously reported. Stent assistance and flow diversion seem associated with reduced recurrence- and re-treatment rates, when compared with primary- and balloon-assisted coiling. Restrained use of stents in ruptured aneurysms may be a contributing factor for higher recurrence/retreatment rates compared to unruptured aneurysms.

Platelet Function Testing in Neurovascular Procedures: Tool or Gimmick?

Background

Platelet inhibitors are used to prevent thromboembolic complications related to neurovascular stenting (NVS) procedures. Despite substantial inter-individual variability of functional platelet inhibition, the value of platelet function tests (PFT) to assess inhibition remains controversial.

Objective

This study was conducted to compare differences in thromboembolic complication rates associated with NVS in platelet-inhibited patients with and without PFT. Clinical neurological outcomes were assessed by differences in the modified Rankin Scale (mRS).

Materials and Methods

One hundred seventeen consecutive patients underwent elective NVS procedures within a 7-year period. All patients received aspirin and clopidogrel 8 days before the procedure. Fifty-two patients were treated without assessment of platelet inhibition, and 65 patients were tested for clopidogrel resistance. When clopidogrel resistance was revealed, corresponding patients were converted to ticagrelor. Changes in mRS and thromboembolic event rates were compared between the 2 cohorts.

Results

Thirty-five percent of patients from the cohort subjected to PFT tests showed inadequate platelet inhi-bition under clopidogrel and were converted to ticagrelor. Compared to the non-PFT test -cohort, neurological deficits were significantly reduced (12 vs. 0%; p = 0.009) and a lower number of thromboembolic events was found (12 vs. 3%; p > 0.05) within the test cohort.

Conclusion

PFT appears to identify patients with clopidogrel resistance prior to NVS procedures. When non-responders are converted to alternative platelet inhibitors, neurological outcomes and thromboembolic complication rates may improve. Consequently, this study provides preliminary evidence that PFT may be a useful clinical tool to enhance procedural safety and improve clinical outcomes in NVS procedures.

Radiation exposure, and procedure and fluoroscopy times in endovascular treatment of intracranial aneurysms: a methodological comparison

BACKGROUND

Limited data are available for radiation exposure, and procedure and fluoroscopy times in neuroendovascular treatment (NET) strategies.

OBJECTIVE

This study establishes and compares related parameters between coil embolization (COIL), balloon assisted coil embolization (BAC), stent assisted coil embolization (SAC), and flow diverting technology (FDT) in NET of intracranial aneurysms.

MATERIALS AND METHODS

Between 2010 and 2017, 249 consecutive intracranial aneurysms underwent NET at a single center, all performed by the same operator. Dose area products (DAP), and procedure and fluoroscopy times were recorded and compared between COIL, BAC, SAC, and FDT techniques. Differences in parameters between cohorts were analyzed for significance using the Mann-Whitney U test, unpaired t test and χ²test. Additional subgroup analysis was performed for emergency and elective cases.

RESULTS

83 aneurysms were treated with COIL (33%), 72 with BAC (29%), 61 with SAC (25%), and 33 with FDT (13%). Baseline characteristics were largely similar within these groups (P>0.05). Among COIL, BAC, and FDT cohorts, no significant difference was found for mean DAP, or procedure and fluoroscopy times (P>0.05). However, compared with all other cohorts, SAC was associated with a significantly higher DAP and longer procedure and fluoroscopy times (P<0.005). No significant difference was recorded for emergency and elective case subgroups.

CONCLUSION

Compared with other NET strategies, SAC was associated with a significantly higher DAP, and longer procedure and fluoroscopy times. This study provides an initial dataset regarding radiation exposure, and procedure and fluoroscopy times for common NET, and may assist ALARA (As Low As Reasonably Achievable) principles to reduce radiation risks.

Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device

We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1–12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies.

Contrasting responses to multiple chemotactic stimuli in transendothelial migration: heterologous desensitization in neutrophils and augmentation of migration in eosinophils

At inflammatory sites in vivo, leukocytes may confront multiple, competing chemoattractive signals. We found significant differences between eosinophils and neutrophils in transendothelial chemotaxis to a chemoattractant diffusing from the lower chamber, when a chemoattractant that binds to another receptor is present at uniform concentration. The transendothelial migration of eosinophils to FMLP, C5a, RANTES, or MCP-3 was totally inhibited by the presence of the homologous chemoattractant, and only RANTES and MCP-3 showed mutual inhibition. C5a and to a lesser extent FMLP chemokinetically stimulated migration to RANTES and MCP-3, without stimulating random migration. Results with neutrophils contrasted. The presence of FMLP not only abrogated neutrophil transmigration to FMLP but also strongly decreased chemotaxis to C5a, IL-8, and Gro-alpha. Similarly, C5a inhibited neutrophil chemotaxis to IL-8 and Gro-alpha. IL-8 almost totally abrogated chemotaxis to Gro-alpha, but Gro-alpha only moderately inhibited chemotaxis to IL-8. Neither IL-8 nor Gro-alpha significantly inhibited transmigration to FMLP or C5a. Actin polymerization in eosinophils and neutrophils was desensitized by the same combinations of chemoattractants that desensitized chemotaxis. We conclude that eosinophils have at least three noninterfering receptor-signal transduction pathways for chemotaxis and actin polymerization. In contrast, the signaling pathways for FMLP, C5a, and IL-8/Gro-alpha in neutrophils are heterologously cross-desensitized, with a hierarchy of resistance to competing signals of FMLP > C5a > IL-8 > Gro-alpha, in agreement with previous results in neutrophils on the Ca2+-mobilizing response. These results may have important implications for the behavior of these cell types in inflammatory sites.

Contrasting responses to multiple chemotactic stimuli in transendothelial migration: heterologous desensitization in neutrophils and augmentation of migration in eosinophils

At inflammatory sites in vivo, leukocytes may confront multiple, competing chemoattractive signals. We found significant differences between eosinophils and neutrophils in transendothelial chemotaxis to a chemoattractant diffusing from the lower chamber, when a chemoattractant that binds to another receptor is present at uniform concentration. The transendothelial migration of eosinophils to FMLP, C5a, RANTES, or MCP-3 was totally inhibited by the presence of the homologous chemoattractant, and only RANTES and MCP-3 showed mutual inhibition. C5a and to a lesser extent FMLP chemokinetically stimulated migration to RANTES and MCP-3, without stimulating random migration. Results with neutrophils contrasted. The presence of FMLP not only abrogated neutrophil transmigration to FMLP but also strongly decreased chemotaxis to C5a, IL-8, and Gro-alpha. Similarly, C5a inhibited neutrophil chemotaxis to IL-8 and Gro-alpha. IL-8 almost totally abrogated chemotaxis to Gro-alpha, but Gro-alpha only moderately inhibited chemotaxis to IL-8. Neither IL-8 nor Gro-alpha significantly inhibited transmigration to FMLP or C5a. Actin polymerization in eosinophils and neutrophils was desensitized by the same combinations of chemoattractants that desensitized chemotaxis. We conclude that eosinophils have at least three noninterfering receptor-signal transduction pathways for chemotaxis and actin polymerization. In contrast, the signaling pathways for FMLP, C5a, and IL-8/Gro-alpha in neutrophils are heterologously cross-desensitized, with a hierarchy of resistance to competing signals of FMLP &gt; C5a &gt; IL-8 &gt; Gro-alpha, in agreement with previous results in neutrophils on the Ca2+-mobilizing response. These results may have important implications for the behavior of these cell types in inflammatory sites.

The C-C chemokine MCP-1 differentially modulates the avidity of beta 1 and beta 2 integrins on T lymphocytes

The ability of chemokines, particularly MCP-1, to induce integrin-dependent binding of T lymphocytes to endothelial adhesion molecules or extracellular matrix (ECM) components was examined. MCP-1 induced significant adhesion to fibronectin (FN) and to endothelial-secreted ECM but not to purified ICAM-1 or VCAM-1, or to activated endothelium. The MCP-1-induced binding of T lymphocytes to FN was rapid, dose dependent, and resulted from activation of both VLA-4 and VLA-5. Like MCP-1, the chemokines RANTES and MIP-1 beta induced T lymphocyte binding to FN, but not to ICAM-1. We suggest therefore, that these T lymphocyte chemokines may be most important, not in initiating integrin-dependent firm adhesion of T lymphocytes to the vascular wall, but rather, in subsequent adhesive interactions during migration into tissue.

Characterization of transendothelial chemotaxis of T lymphocytes

We have adapted a chemotaxis assay using human umbilical vein endothelial cell (HUVEC) monolayers on microporous membranes for studying lymphocyte transendothelial chemotaxis in vitro. Supernatants of peripheral blood mononuclear cells stimulated with phytohemagglutinin (PHA) were identified as an excellent source of lymphocyte chemoattractant activity. The activity in PHA supernatant typically caused 2-6% of peripheral blood lymphocytes (PBL) to transmigrate compared to 0.1-0.3% to media control. Checkerboard analysis demonstrated that transmigration was directional and not attributable to random locomotion. Purified T lymphocytes also underwent transendothelial chemotaxis to PHA supernatant. Using monoclonal antibodies to several human adhesion receptors, we found that the interaction between LFA-1 and ICAM-1/ICAM-2 was more important for transendothelial lymphocyte chemotaxis than the interaction between VLA-4 and VCAM-1. A monoclonal antibody to the beta 1 integrin subunit inhibited chemotaxis more than antibodies to the VLA alpha 2, alpha 3, alpha 4, or alpha 5 subunits. The transendothelial assay was used to guide purification of the lymphocyte chemoattractant activity, which we reported previously to be monocyte chemoattractant protein-1 (MCP-1) (Carr et al., Proc. Natl. Acad. Sci. USA (1994) 91, 3652). The adhesion molecules required for chemotaxis to MCP-1 were similar to those with PHA supernatant. The use of HUVEC in the assay enhances the signal-to-background ratio of chemotaxis and provides a model that is physiologically relevant to lymphocyte emigration from the bloodstream into sites of inflammation.

C-C chemokines, but not the C-X-C chemokines interleukin-8 and interferon-gamma inducible protein-10, stimulate transendothelial chemotaxis of T lymphocytes

Eight chemokines were tested for ability to elicit transendothelial chemotaxis of unstimulated peripheral blood T lymphocytes. The C-C chemokines monocyte chemotactic protein (MCP)-2, MCP-3, RANTES, macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, and, as previously described, MCP-1 induced significant, dose-dependent transendothelial chemotaxis of CD3+ T lymphocytes. In contrast, the C-X-C chemokines interleukin-8 (IL-8) and interferon-gamma inducible protein-10 (IP-10) failed to induce transendothelial chemotaxis of CD3+ T lymphocytes or T lymphocyte subsets. RANTES, MIP-1 alpha, and MIP-1 beta induced significant transendothelial chemotaxis of CD4+, CD8+, and CD45R0+ T lymphocyte subsets. Phenotyping of mononuclear cells that underwent transendothelial migration to MCP-2, MCP-3, RANTES, or MIP-1 alpha showed both monocytes and activated (CD26 high), memory-type (CD45R0+) T cells. Both CD4+ and CD8+ T lymphocytes were recruited, but not natural killer cells or significant numbers of B cells. MCP-2 was the only C-C chemokine tested that attracted a significant number of naive-type (CD45RA+) T lymphocytes. In the absence of endothelium, IL-8 but not IP-10 promoted modest but significant chemotoxis of CD3+ T lymphocytes. Our data support the hypothesis that C-C, not the C-X-C chemokines IL-8 or IP-10, promote transendothelial chemotaxis of T lymphocytes.

The integrin VLA-4 supports tethering and rolling in flow on VCAM-1

Selectins have previously been shown to tether a flowing leukocyte to a vessel wall and mediate rolling. Here, we report that an intergrin, VLA-4, can also support tethering and rolling. Blood T lymphocytes and alpha 4 integrin-transfected cells can tether in shear flow, and then roll, through binding of the intergrin VLA-4 to purified VCAM-1 on the wall of a flow chamber. VLA-4 transfectants showed similar tethering and rolling on TNF-stimulated endothelium. Tethering efficiency, rolling velocity, and resistance to detachment are related to VCAM-1 density. Tethering and rolling did not occur on ICAM-1, fibronectin, or fibronectin fragments, and tethering did not require integrin activation or the presence of an alpha 4 cytoplasmic domain. Arrest of rolling cells on VCAM-1 occurred spontaneously, and/or was triggered by integrin activating agents Mn2+, phorbol ester, and mAb TS2/16. These agents, and the alpha 4 cytoplasmic domain, promoted increased resistance to detachment. Together the results show that VLA-4 is a versatile integrin that can mediate tethering, rolling, and firm arrest on VCAM-1.

Monocyte chemoattractant protein 1 acts as a T-lymphocyte chemoattractant

We have utilized a transendothelial lymphocyte chemotaxis assay to identify and purify a lymphocyte chemoattractant in supernatants of mitogen-stimulated peripheral blood mononuclear cells. Amino acid sequence analysis revealed identity with monocyte chemoattractant protein 1 (MCP-1), a chemoattractant previously thought to be specific for monocytes. Recombinant MCP-1 is chemoattractive for purified T lymphocytes and for CD3+ lymphocytes in peripheral blood lymphocyte preparations. The T-cell response to MCP-1 is dose-dependent and chemotactic, rather than chemokinetic. Phenotyping of chemoattracted T lymphocytes shows they are an activated memory subset. The response to MCP-1 by T lymphocytes can be duplicated in the absence of an endothelial monolayer and the majority of T-lymphocyte chemotactic activity in mitogen-stimulated peripheral blood mononuclear cell supernatants can be neutralized by antibody to MCP-1. Thus, MCP-1 is the major lymphocyte chemoattractant secreted by mitogen-stimulated peripheral blood mononuclear cells and is capable of acting as a potent T-lymphocyte, as well as monocyte, chemoattractant. This may help explain why monocytes and T lymphocytes of the memory subset are always found together at sites of antigen-induced inflammation.

To treat or not to treat: the controversy of handicapped newborns

When dealing with the prospects of treating, not treating, or delaying treatment for handicapped newborns, there is no room for error. Since that is an impossible premise, one must make the best possible treatment plan for the newborn. The parents and members of the health care team should be included in the decision making. Those involved must also remember that no decisions are final; if the infant's physical condition changes, the treatment plan may be reevaluated. Any errors must be made by promoting the best interests of the infant in question, by keeping the infant alive longer than necessary rather than providing a premature death. Never, under any circumstances, should an infant be starved, dehydrated, or outright killed; to do so is to violate the rights of the infant. The infant's rights to life without constant pain are also violated by the senseless prolongation of his life and the promotion of wrongful life through the excessive use of modern technology.

To treat or not to treat: the controversy of handicapped newborns

When dealing with the prospects of treating, not treating, or delaying treatment for handicapped newborns, there is no room for error. Since that is an impossible premise, one must make the best possible treatment plan for the newborn. The parents and members of the health care team should be included in the decision making. Those involved must also remember that no decisions are final; if the infant's physical condition changes, the treatment plan may be reevaluated. Any errors must be made by promoting the best interests of the infant in question, by keeping the infant alive longer than necessary rather than providing a premature death. Never, under any circumstances, should an infant be starved, dehydrated, or outright killed; to do so is to violate the rights of the infant. The infant's rights to life without constant pain are also violated by the senseless prolongation of his life and the promotion of wrongful life through the excessive use of modern technology.