I was interested to read the paper by Yamauchi K and colleagues published in J Neurointerv Surg 2017 Sep. Hyperperfusion syndrome after carotid interventions has a low incidence but it can lead to morbidity and mortality. The aim of the authors was to evaluate the usefulness of quantitative DSA for predicting hyperperfusion phenomenon (HPP) after carotid artery stenting and angioplasty. Thirty-three consecutive patients with carotid stenosis treated with carotid artery stenting or angioplasty between February 2014 and August 2016 were included. The cerebral circulation time (CCT) was defined as the difference in the relative time to maximum intensity between arterial and venous regions of interest set on the angiograms. HPP was diagnosed straight after the procedure with qualitative 123I-IMP single-photon emission CT (SPECT). Cut-off points for detecting HPP for preprocedural CCT and periprocedural change of CCT were assessed by receiver operating characteristic analysis using 123I-IMP SPECT as reference standard. Differences between patients with and without HPP were analyzed by Student's t test for continuous variables and Fisher`s exact test for categorical variables. A p value of <0.05 was considered statistically significant. Receiver operating characteristic curve analysis of preprocedural CCT and ΔCCT was performed for the prediction of HPP, with 123I-IMP SPECT as standard of reference. They reported that the optimal cut-off points of preprocedural CCT and c...
I was interested to read the paper by Yamauchi K and colleagues published in J Neurointerv Surg 2017 Sep. Hyperperfusion syndrome after carotid interventions has a low incidence but it can lead to morbidity and mortality. The aim of the authors was to evaluate the usefulness of quantitative DSA for predicting hyperperfusion phenomenon (HPP) after carotid artery stenting and angioplasty. Thirty-three consecutive patients with carotid stenosis treated with carotid artery stenting or angioplasty between February 2014 and August 2016 were included. The cerebral circulation time (CCT) was defined as the difference in the relative time to maximum intensity between arterial and venous regions of interest set on the angiograms. HPP was diagnosed straight after the procedure with qualitative 123I-IMP single-photon emission CT (SPECT). Cut-off points for detecting HPP for preprocedural CCT and periprocedural change of CCT were assessed by receiver operating characteristic analysis using 123I-IMP SPECT as reference standard. Differences between patients with and without HPP were analyzed by Student's t test for continuous variables and Fisher`s exact test for categorical variables. A p value of <0.05 was considered statistically significant. Receiver operating characteristic curve analysis of preprocedural CCT and ΔCCT was performed for the prediction of HPP, with 123I-IMP SPECT as standard of reference. They reported that the optimal cut-off points of preprocedural CCT and change of CCT for predicting HPP were 8.0 s (100% sensitivity, 69% specificity) and 3.2 s (75% sensitivity, 100% specificity), respectively. The study suggested that preprocedural prolongation and greater periprocedural change of CCT are associated with the occurrence of HPP. Periprocedural evaluation of CCT may be useful for predicting HPP.1
However, this result has nothing to do with prediction. First, sensitivity and specificity are among estimates that are used to evaluate the diagnostic accuracy of a single test compared to a gold standard. Moreover, for prediction studies, we need data from two different cohorts or at least from one cohort divided into two to first to develop a prediction model and subsequently validate it. Misleading results are generally the main outcome of research that fails to validate its prediction models. 2-5
It is good to know that association dose not necessarily means prediction. Finally, in prediction studies, we must assess the interactions between important variables. Final results can be impacted dramatically when qualitative interactions are present. 2-5 This means that most of the time, without assessing the interaction terms, prediction studies will mainly produce misleading messages.
Keywords: angiography; angioplasty; stent; prediction; methodological issues
References:
1. Yamauchi K, Enomoto Y, Otani K, et al. Prediction of hyperperfusion phenomenon after carotid artery stenting and carotid angioplasty using quantitative DSA with cerebral circulation time imaging. J Neurointerv Surg. 2017 Sep 2. pii: neurintsurg-2017-013259. doi: 10.1136/neurintsurg-2017-013259. [Epub ahead of print]
2. Rothman KJ, Sander Greenland, Timothy L. Lash. Cohort studies. In: Rothman KJ. Modern Epidemiology, 3rd edition. Baltimore, United States: Lippincott Williams & Wilkins; 2008. P.79-85.
3. Sabour S. Prognostic prediction by liver tissue proteomic profiling in patients with colorectal liver metastases; rule of thumb. Future Oncol. 2017 Jun;13(13):1133-1134.
4. Sabour S. Prediction of preterm delivery using levels of VEGF and leptin in amniotic fluid from the second trimester: prediction rules. Arch Gynecol Obstet. 2015 Apr;291(4):719.
5. Sabour S, Ghassemi F. Predictive value of confocal scanning laser for the onset of visual field loss. Ophthalmology. 2013 Jun;120(6):e31-2.
We read with interest the recent paper looking at venous sinus pressure gradients prior to stenting (1), and commend the authors for their work on this interesting topic. We also share an interest in the subject, and recently published our experience looking at venous stenting in a similar patient population (2). The authors of the current paper documented significant differences in trans-stenotic venous pressure-gradients measured under general anaesthesia (GA), and suggested that pressure measurements should be performed with patients awake to counteract this. Another paper published in this issue of JNIS also documented the disparities between pressure measurements performed under GA versus those performed under conscious sedation (CS) (3). The pressure differences in our paper were significantly more marked in those patients who underwent measurements under local anaesthesia alone versus under CS. We can therefore hypothesise that even the use of CS can result in changes in the measured venous pressures in these patients, and indeed in the current paper the authors noted that the use of midazolam in their awake patients had a statistically significant effect on the pressures obtained. Since the decision to treat often hinges on this all-important measurement, we thus propose that venous sinus pressure measurements should be always performed using local anaesthesia alone, in an effort to minimise this variability.
1: Fargen KM, Spiotta AM, Hyer M, et al, Comparis...
We read with interest the recent paper looking at venous sinus pressure gradients prior to stenting (1), and commend the authors for their work on this interesting topic. We also share an interest in the subject, and recently published our experience looking at venous stenting in a similar patient population (2). The authors of the current paper documented significant differences in trans-stenotic venous pressure-gradients measured under general anaesthesia (GA), and suggested that pressure measurements should be performed with patients awake to counteract this. Another paper published in this issue of JNIS also documented the disparities between pressure measurements performed under GA versus those performed under conscious sedation (CS) (3). The pressure differences in our paper were significantly more marked in those patients who underwent measurements under local anaesthesia alone versus under CS. We can therefore hypothesise that even the use of CS can result in changes in the measured venous pressures in these patients, and indeed in the current paper the authors noted that the use of midazolam in their awake patients had a statistically significant effect on the pressures obtained. Since the decision to treat often hinges on this all-important measurement, we thus propose that venous sinus pressure measurements should be always performed using local anaesthesia alone, in an effort to minimise this variability.
1: Fargen KM, Spiotta AM, Hyer M, et al, Comparison of venous sinus manometry gradients obtained while awake and under general anesthesia before venous sinus stenting. Journal of NeuroInterventional Surgery 2017;9:990-993
2: Lenck S, Vallée F, Labeyrie MA et al, Stenting of the lateral sinus in idiopathic intracranial hypertension according to the type of stenosis. Neurosurgery. 2017 Jan 13;80(3):393-400
3: Raper DMS, Buell TJ, Chen C, et al, Intracranial venous pressures under conscious sedation and general anesthesia Journal of NeuroInterventional Surgery 2017;9:986-989
We appreciate the interest shown by Drs. Yao and You (1) in our paper (2) and find it our pleasure to address their concerns.
The first point raised by Drs. Yao and You is that our search strategy missed two articles, namely those of Mortimer et al (2015) (3) and Morgan et al (1996) (4). We would like to reassure Drs. Yao and You that we did screen these articles, and decided against including them in our meta-analysis based on our inclusion criteria. The article by Mortimer et al (2015) (3) describes a patient population where balloon angioplasty, verapamil, and papaverine infusions were used separately or in various combinations. They did not break down their results by the specific intra-arterial vasodilator (IAD) used, and therefore we decided not to include this information. The paper by Morgan et al (1996) (4) describes a patient population which overlapped with that described by the same group in another paper, Morgan et al (2000) (5). We had personally communicated with the authors in 2016 regarding the multiple papers from this group, such as Little et al (1994) (6) and Morgan et al (2000)
(5) that described papaverine infusions for vasospasm. We found out that there were overlaps in these study populations, and that the cohort in the 2000 paper(5) was the most complete. Therefore, only this paper was included in our meta-analysis, while the earlier ones were excluded.
The second suggestion by Drs. Yao and You was to perform a regression ana...
We appreciate the interest shown by Drs. Yao and You (1) in our paper (2) and find it our pleasure to address their concerns.
The first point raised by Drs. Yao and You is that our search strategy missed two articles, namely those of Mortimer et al (2015) (3) and Morgan et al (1996) (4). We would like to reassure Drs. Yao and You that we did screen these articles, and decided against including them in our meta-analysis based on our inclusion criteria. The article by Mortimer et al (2015) (3) describes a patient population where balloon angioplasty, verapamil, and papaverine infusions were used separately or in various combinations. They did not break down their results by the specific intra-arterial vasodilator (IAD) used, and therefore we decided not to include this information. The paper by Morgan et al (1996) (4) describes a patient population which overlapped with that described by the same group in another paper, Morgan et al (2000) (5). We had personally communicated with the authors in 2016 regarding the multiple papers from this group, such as Little et al (1994) (6) and Morgan et al (2000)
(5) that described papaverine infusions for vasospasm. We found out that there were overlaps in these study populations, and that the cohort in the 2000 paper(5) was the most complete. Therefore, only this paper was included in our meta-analysis, while the earlier ones were excluded.
The second suggestion by Drs. Yao and You was to perform a regression analysis to “solve” the heterogeneity. For a methodically sound meta-analysis, heterogeneity is always presumed to exist, as statistical analysis is but one means of measuring it. When statistically significant heterogeneity is found, it should be quantified and accounted for with subgroup and sensitivity analysis, and subsequently potential contributors to it also discussed subjectively. Meta-regression is another step to account for it. Given the relatively small sample sizes and the observational nature of the included studies, we felt a meta-regression would not do justice to the available data, and would be overreaching.
Finally, they note that several of our studies used balloon angioplasty in addition to IADs, which might have significantly influenced our findings of IAD efficacy and safety. This is a valid concern, which we had anticipated and stated in the limitations section of our manuscript that, “IAD and balloon angioplasty were used in combination in many patients, which may confound our results when the aim was to isolate the effects of IADs”(2). During our data abstraction, we noted that most studies did not separately report data for IADs and balloon angioplasty, and often used these in conjunction. In the interest of retaining sufficient sample sizes for our analysis, we were left with no recourse but to accept even those studies that included balloon angioplasty along with IADs.
We would once again like to thank Drs. Yao and You for their interest in our paper, and their insightful questions.
Authors
References
1. Yao ZY, C. Intra-arterial vasodilators for vasospasm following aneurysmal subarachnoid hemorrhage. Journal of Neurointerventional Surgery. 2017.
2. Venkatraman A, Khawaja AM, Gupta S, Hardas S, Deveikis JP, Harrigan MR, et al. Intra-arterial vasodilators for vasospasm following aneurysmal subarachnoid hemorrhage: a meta-analysis. J Neurointerv Surg. 2017.
3. Mortimer AM, Steinfort B, Faulder K, Bradford C, Finfer S, Assaad N, et al. The detrimental clinical impact of severe angiographic vasospasm may be diminished by maximal medical therapy and intensive endovascular treatment. J Neurointerv Surg. 2015;7(12):881-7.
4. Morgan M, Halcrow S, Sorby W, Grinnell V. Outcome of aneurysmal subarachnoid haemorrhage following the introduction of papaverine angioplasty. J Clin Neurosci. 1996;3(2):139-42.
5. Morgan MK, Jonker B, Finfer S, Harrington T, Dorsch NW. Aggressive management of aneurysmal subarachnoid haemorrhage based on a papaverine angioplasty protocol. J Clin Neurosci. 2000;7(4):305-8.
6. Little N, Morgan MK, Grinnell V, Sorby W. Intra-arterial papaverine in the management of cerebral vasospasm following subarachnoid haemorrhage. J Clin Neurosci. 1994;1(1):42-6.
With great interest, we read the article of Venkatraman et al.[1] published in the Journal of NeuroInterventional Surgery recently. They presented a comprehensive picture depicting the effect of intra-arterial vasodilators (IADs) on the vasospasm following aneurysmal subarachnoid hemorrhage. But we were concerned with several questions weakening the reliability and generalization of the meta-analysis.
Firstly , though the detailed including criteria and searching strategy were provided in their meta-analysis, at least two eligible studies2,3 were missed which conformed to their including criteria and unfulfilled the excluding criteria. Two cohort studies of Morgan [2] and Mortimer [3] reported the effects of IADs on vasospasm with documentation of interested events, which should be included in Venkatraman’s analysis. Whether addition of these two studies could change the overall effect of IADs was unclear, but including any eligible study was in accordance with PRISMA principle.
Secondly, owing to the large number of included studies, the heterogeneity was substantial. Venkatraman et al.[1] conducted subgroup and sensitivity analyses, in which the heterogeneity remained significant (most values of I2 greater than 50%). It was rationale to turn to regression analyses in order to find and solve the heterogeneity.
Besides, this article included studies combining IADs with balloon angioplasty, which might overestimate effectiveness of IADs. IADs w...
With great interest, we read the article of Venkatraman et al.[1] published in the Journal of NeuroInterventional Surgery recently. They presented a comprehensive picture depicting the effect of intra-arterial vasodilators (IADs) on the vasospasm following aneurysmal subarachnoid hemorrhage. But we were concerned with several questions weakening the reliability and generalization of the meta-analysis.
Firstly , though the detailed including criteria and searching strategy were provided in their meta-analysis, at least two eligible studies2,3 were missed which conformed to their including criteria and unfulfilled the excluding criteria. Two cohort studies of Morgan [2] and Mortimer [3] reported the effects of IADs on vasospasm with documentation of interested events, which should be included in Venkatraman’s analysis. Whether addition of these two studies could change the overall effect of IADs was unclear, but including any eligible study was in accordance with PRISMA principle.
Secondly, owing to the large number of included studies, the heterogeneity was substantial. Venkatraman et al.[1] conducted subgroup and sensitivity analyses, in which the heterogeneity remained significant (most values of I2 greater than 50%). It was rationale to turn to regression analyses in order to find and solve the heterogeneity.
Besides, this article included studies combining IADs with balloon angioplasty, which might overestimate effectiveness of IADs. IADs worked in coordination with balloon angioplasty, for balloon angioplasty dilated proximal vessel assisting IADs to expand distal vessels. We could not exclude the possibility partial effect on the outcomes was attributable to balloon angioplasty. Similarly, it was reasonable to ascribe many complications to the balloon angioplasty, like vessel perforation.
In all, we would like to congratulate Venkatraman for the great work of meta-analyzing the impact of IADs on the treatment of vasospasm following subarachnoid hemorrhage.
References
1. Venkatraman A, Khawaja AM, Gupta S, et al. Intra-arterial vasodilators for vasospasm following aneurysmal subarachnoid hemorrhage: a meta-analysis. J Neurointerv Surg. 2017.
2. Morgan M, Halcrow S, Sorby W, Grinnell V. Outcome of aneurysmal subarachnoid haemorrhage following the introduction of papaverine angioplasty. J Clin Neurosci. 1996;3(2):139-142.
3. Mortimer AM, Steinfort B, Faulder K, et al. The detrimental clinical impact of severe angiographic vasospasm may be diminished by maximal medical therapy and intensive endovascular treatment. Journal of Neurointerventional Surgery. 2015;7(12):881-887.
We would like to thank Dr. Shotar and colleagues for their interest in our article. As highlighted by Dr. Shotar, delayed enhancing lesions (DEL) after coil embolization of aneurysm are suspected as a result of foreign body reaction 1-5. We agree with their opinion that the catheter coating of the inner wall of guiding catheter and/or the outer wall of microcatheter may be the source of foreign body. However, according to our experiences and analysis, it is our opinion that the coating material of the inner wall of microcatheter may also be the source.
Dr Shotar suggests that the distribution of the MR lesions in the territory of the parent artery (i.e.: ICA) in our series suggests the guiding catheter as the culprit. However, in all our cases 6, the aneurysms were located at the distal ICA (Ophthalmic artery, IC-anterior choroidal artery, superior hypophyseal artery). Thus, we believe that the distribution of the DELs on MR is not in conflict with our claim that the inner wall of the microcatheter is the source. Foreign body fragments from the microcatheter probably migrated into the aneurysmal sac during multiple coil introduction attempts under unusual friction and were swept downstream. Our benchtop analyses also support this finding.
Regarding Dr Shotar’s suggestion that "the patient treated with the microcatheter that showed coating fragments at the location of the friction on bench tests did not have DELs", this microcatheter was withdrawn imme...
We would like to thank Dr. Shotar and colleagues for their interest in our article. As highlighted by Dr. Shotar, delayed enhancing lesions (DEL) after coil embolization of aneurysm are suspected as a result of foreign body reaction 1-5. We agree with their opinion that the catheter coating of the inner wall of guiding catheter and/or the outer wall of microcatheter may be the source of foreign body. However, according to our experiences and analysis, it is our opinion that the coating material of the inner wall of microcatheter may also be the source.
Dr Shotar suggests that the distribution of the MR lesions in the territory of the parent artery (i.e.: ICA) in our series suggests the guiding catheter as the culprit. However, in all our cases 6, the aneurysms were located at the distal ICA (Ophthalmic artery, IC-anterior choroidal artery, superior hypophyseal artery). Thus, we believe that the distribution of the DELs on MR is not in conflict with our claim that the inner wall of the microcatheter is the source. Foreign body fragments from the microcatheter probably migrated into the aneurysmal sac during multiple coil introduction attempts under unusual friction and were swept downstream. Our benchtop analyses also support this finding.
Regarding Dr Shotar’s suggestion that "the patient treated with the microcatheter that showed coating fragments at the location of the friction on bench tests did not have DELs", this microcatheter was withdrawn immediately after detection of unusual friction without additional coil introduction attempts. We believe that ‘immediate withdrawl’ was essential in preventing distal migration of foreign body materials.
We agree with Dr Shotar’s analyses on the recent increase in the literature on such complications. Further investigation is necessary for identification of its causes. In the meanwhile, based on our series and the experiences of others, we believe that both the inner and outer walls of the micro and/or guiding catheters may be the source 1 6. Our main interest was to identify the cause and elucidate the signs during the procedure –unusual friction development- at which such phenomenon occurs so that clinical complications may be prevented.
1. Shotar E, Law-Ye B, Baronnet-Chauvet F, et al. Non-ischemic cerebral enhancing lesions secondary to endovascular aneurysm therapy: nickel allergy or foreign body reaction? Case series and review of the literature. Neuroradiology 2016 doi: 10.1007/s00234-016-1699-5 [published Online First: 2016/05/25]
2. Shapiro M, Ollenschleger MD, Baccin C, et al. Foreign Body Emboli following Cerebrovascular Interventions: Clinical, Radiographic, and Histopathologic Features. AJNR American journal of neuroradiology 2015;36(11):2121-6. doi: 10.3174/ajnr.A4415 [published Online First: 2015/08/22]
3. Cruz J, Marotta T, O'Kelly C, et al. Enhancing Brain Lesions after Endovascular Treatment of Aneurysms. American Journal of Neuroradiology 2014
4. Skolarus LE, Gemmete JJ, Braley T, et al. Abnormal white matter changes after cerebral aneurysm treatment with polyglycolic-polylactic acid coils. World neurosurgery 2010;74(6):640-4. doi: 10.1016/j.wneu.2010.03.026 [published Online First: 2011/04/16]
5. Fealey ME, Edwards WD, Giannini C, et al. Complications of endovascular polymers associated with vascular introducer sheaths and metallic coils in 3 patients, with literature review. The American journal of surgical pathology 2008;32(9):1310-16.
6. Oh SW, Shin NY, Lee HJ, et al. Delayed enhancing lesions after coil embolization of aneurysms: clinical experience and benchtop analyses. Journal of neurointerventional surgery 2017 doi: 10.1136/neurintsurg-2016-012833 [published Online First: 2017/01/08]
We read with great interest the article by McTaggart et al. on the new embolectomy technique called Continuous Aspiration Prior To Intracranial Vascular Embolectomy (CAPTIVE).(1) The paper adds information on the supporting evidence that a combined approach of stentretriever and aspiration-catheter utilization may be the optimal path in achieving higher rates of complete reperfusion in patients with large vessel occlusions.(2, 3) While the idea of starting aspiration with the intermediate catheter prior to and during the stentretriever placement is intriguing, attention has to be paid on the effect of prolonged aspiration on collateral flow, as reported in a recent JNIS publication.(4) Additionally, the ‘continuous’ part of the title may be misleading, as the authors state that they advance the aspiration-catheter towards the face of the clot until the drip rate has stopped. As seen in Fig 1E of the CAPTIVE publication, the tip of the aspiration-catheter becomes clogged with clot as ‘a portion is held captive within the distal aspiration catheter.’ This probably results in vacuum within the aspiration-catheter and non-existent aspiration in the vicinity of the aspiration-catheter tip during immobilization of the stentretriever/clot/aspiration-catheter unit. At last, the authors describe thoroughly a ‘De-CAPTIVE shear’ on Fig 2 but neglect to acknowledge that the same danger of clot-shearing applies to the moments of stentretriever/clot/aspiration-cath...
We read with great interest the article by McTaggart et al. on the new embolectomy technique called Continuous Aspiration Prior To Intracranial Vascular Embolectomy (CAPTIVE).(1) The paper adds information on the supporting evidence that a combined approach of stentretriever and aspiration-catheter utilization may be the optimal path in achieving higher rates of complete reperfusion in patients with large vessel occlusions.(2, 3) While the idea of starting aspiration with the intermediate catheter prior to and during the stentretriever placement is intriguing, attention has to be paid on the effect of prolonged aspiration on collateral flow, as reported in a recent JNIS publication.(4) Additionally, the ‘continuous’ part of the title may be misleading, as the authors state that they advance the aspiration-catheter towards the face of the clot until the drip rate has stopped. As seen in Fig 1E of the CAPTIVE publication, the tip of the aspiration-catheter becomes clogged with clot as ‘a portion is held captive within the distal aspiration catheter.’ This probably results in vacuum within the aspiration-catheter and non-existent aspiration in the vicinity of the aspiration-catheter tip during immobilization of the stentretriever/clot/aspiration-catheter unit. At last, the authors describe thoroughly a ‘De-CAPTIVE shear’ on Fig 2 but neglect to acknowledge that the same danger of clot-shearing applies to the moments of stentretriever/clot/aspiration-catheter unit retraction within the tip of the guide catheter/sheath. This exact case is depicted in our example ( http://onestopinstroke.eu/wp-content/uploads/Fig1-1.jpg ) during embolectomy of a mid-basilar occlusion (A). B shows recanalization of the occlusion after one maneuver but without proximal aspiration on the guide catheter there is clot-shearing at the catheter tip seen on the early images of the series (C), with dislocation of the clot towards the basilar artery during the angiogram (D and E). Control-angiogram shows re-occlusion of the basilar artery (F) which could be recanalized with another maneuver (G), but resulted in an incomplete reperfusion of the downstream territory. This danger can be reduced by applying aspiration on the guide catheter during retraction of the unit, while preserving vacuum within the aspiration catheter either with pump-aspiration or with the use of a vacuum-lock syringe. In our experience, the addition of proximal aspiration to a primarily combined approach (stentretriever plus aspiration-catheter) results in high rates of mTICI3 reperfusion.(3)
1. McTaggart RA, Tung EL, Yaghi S, Cutting SM, Hemendinger M, Gale HI, et al. Continuous aspiration prior to intracranial vascular embolectomy (CAPTIVE): a technique which improves outcomes. Journal of neurointerventional surgery. 2016. Epub 2016/12/18.
2. Massari F, Henninger N, Lozano JD, Patel A, Kuhn AL, Howk M, et al. ARTS (Aspiration-Retriever Technique for Stroke): Initial clinical experience. Interventional neuroradiology : journal of peritherapeutic neuroradiology, surgical procedures and related neurosciences. 2016;22(3):325-32. Epub 2016/02/26.
3. Maus V, Behme D, Kabbasch C, Borggrefe J, Tsogkas I, Nikoubashman O, et al. Maximizing First-Pass Complete Reperfusion with SAVE. Clinical neuroradiology. 2017. Epub 2017/02/15.
4. Lally F, Soorani M, Woo T, Nayak S, Jadun C, Yang Y, et al. In vitro experiments of cerebral blood flow during aspiration thrombectomy: potential effects on cerebral perfusion pressure and collateral flow. Journal of neurointerventional surgery. 2016;8(9):969-72. Epub 2015/09/01.
With great interest we read the recent paper by Martinez-Galdámez et al. regarding the periprocedural outcomes and early safety after placement of a Pipeline Embolization Device with Shield Technology (PEDshield) (1). Evaluation of new endovascular devices, such as PEDshield, is of the utmost importance to give future users a chance to objectively review possible benefits for their clinical practice.
In the study of Martinez-Galdámez et al. 76% of the target aneurysms were small (< 10 mm). It is known that small aneurysms are associated with a lower probability of thromboembolisms and ischemic stroke after flow diverter treatment than large and giant aneurysms (2,3). The size of the treated aneurysms, and not the PEDshield, might therefore explain the lack of thromboembolic complications reported in the study of Martinez-Galdámez et al. Selection bias might thus have led to the conclusion that the early safety of the PEDshield device is warranted.
Furthermore, it is hard to understand why only 21 out of 50 patients (42%) underwent platelet reactivity testing, especially since the primary outcome measure focused on identifying thromboembolic complications in the territory supplied by the treated artery. To make matters worse: when platelet reactivity tests revealed the presence of hyporesponders, anti-platelet therapy was left unchanged in most cases. If thromboembolic complications do occur in the 6-month and 1-year follow-up of this...
With great interest we read the recent paper by Martinez-Galdámez et al. regarding the periprocedural outcomes and early safety after placement of a Pipeline Embolization Device with Shield Technology (PEDshield) (1). Evaluation of new endovascular devices, such as PEDshield, is of the utmost importance to give future users a chance to objectively review possible benefits for their clinical practice.
In the study of Martinez-Galdámez et al. 76% of the target aneurysms were small (< 10 mm). It is known that small aneurysms are associated with a lower probability of thromboembolisms and ischemic stroke after flow diverter treatment than large and giant aneurysms (2,3). The size of the treated aneurysms, and not the PEDshield, might therefore explain the lack of thromboembolic complications reported in the study of Martinez-Galdámez et al. Selection bias might thus have led to the conclusion that the early safety of the PEDshield device is warranted.
Furthermore, it is hard to understand why only 21 out of 50 patients (42%) underwent platelet reactivity testing, especially since the primary outcome measure focused on identifying thromboembolic complications in the territory supplied by the treated artery. To make matters worse: when platelet reactivity tests revealed the presence of hyporesponders, anti-platelet therapy was left unchanged in most cases. If thromboembolic complications do occur in the 6-month and 1-year follow-up of this cohort, it will make interpretation of the primary outcome measure more difficult as it will be impossible to rule out ineffective anti-platelet therapy.
References
1) Martinez-Galdámez M, Lamin SM, Lagios KG, et al. Periprocedural outcomes and early safety with the use of Pipeline Flex Embolization Device with Shield Technology for unruptured intracranial aneurysms: preliminary results from a prospective clinical study. J Neurointervent Surg 2017;0:1-6.
2) Heller RS, Dandamundi V, Lanfranchi M, et al. Effect of antiplatelet therapy on thromboembolism after flow diversion with the Pipeline Embolization Device. J Neurosurg 2013;119:1603-10.
3) Brinjikji W, Murad MH, Lanzino G, et al. Endovascular treatment of intracranial aneurysms with flow diverters. A meta-analysis. Stroke 2013;44:442-7.
We have read with great interest the article describing the CAPTIVE technique for endovascular acute ischemic treatment by McTaggart et al.1. Firstly, we would like to commend the great clarity they used to describe the combination of distal aspiration and stent retriever to perform mechanical thrombectomy. Notably, they illustrated the rationale for aspiration prior to stent deployment as well as the removal of both distal aspiration catheter and stent as a single unit to decrease possible clot fragmentation.
We adopt a very similar approach for most of our cases, although we would like to emphasize a slight variant that appears clinically interesting.
In combination with stent retrievers, the balloon guide catheter (BGC) has been shown to improve the effectiveness of mechanical thrombectomy2, 3. In our experience, we typically use the CAPTIVE technique in association with a BGC which presents several potential advantages.
Firstly, in cases of tortuous anatomy it provides excellent support for navigating the distal aspiration catheter. In addition, the balloon can be temporarily inflated at this stage to provide an anchoring effect in order to avoid potential push back of the guiding catheter4.
Secondly, McTaggart et al. reported 5% embolization to new territory with the CAPTIVE technique; an equivalent rate to previous reports on distal aspiration with no stent retriever5. In an in vitro study, Chueh et al.6 demonstrated a significant decrease o...
We have read with great interest the article describing the CAPTIVE technique for endovascular acute ischemic treatment by McTaggart et al.1. Firstly, we would like to commend the great clarity they used to describe the combination of distal aspiration and stent retriever to perform mechanical thrombectomy. Notably, they illustrated the rationale for aspiration prior to stent deployment as well as the removal of both distal aspiration catheter and stent as a single unit to decrease possible clot fragmentation.
We adopt a very similar approach for most of our cases, although we would like to emphasize a slight variant that appears clinically interesting.
In combination with stent retrievers, the balloon guide catheter (BGC) has been shown to improve the effectiveness of mechanical thrombectomy2, 3. In our experience, we typically use the CAPTIVE technique in association with a BGC which presents several potential advantages.
Firstly, in cases of tortuous anatomy it provides excellent support for navigating the distal aspiration catheter. In addition, the balloon can be temporarily inflated at this stage to provide an anchoring effect in order to avoid potential push back of the guiding catheter4.
Secondly, McTaggart et al. reported 5% embolization to new territory with the CAPTIVE technique; an equivalent rate to previous reports on distal aspiration with no stent retriever5. In an in vitro study, Chueh et al.6 demonstrated a significant decrease of distal emboli when a BGC is combined with a stent retriever. They also showed an increased risk of distal embolization when using the direct aspiration technique (ADAPT). Since the CAPTIVE technique has evolved from the ADAPT technique, so similarly, once the clot is engaged inside the aspiration catheter the flow reversal stops. By promoting flow arrest, the addition of a BGC could potentially decrease the rate of embolization in new territory, particularly in cases of either long clots incompletely covered by the stent or soft elastic clots, as suggested in vitro6.
Finally, the large lumen of the BGC is likely to avoid any shearing of the embolus during withdrawal of the distal aspiration catheter inside the guiding catheter. A similar potential hazard was importantly illustrated by McTaggart et al. in cases of inadvertent advance of the distal aspiration catheter over the clot-stent complex during removal of the stent.
The use of a BGC in addition to the CAPTIVE technique could however pose certain limitations. Firstly, navigating a 9F catheter is clearly more challenging than a 6F catheter, particularly in cases of tortuous anatomy; although often an exchange manoeuver over a stiff wire allows an appropriate positioning of the BGC in the targeted vessel. The aspiration from the BGC is here limited due to the triaxial approach, hower the additional effect of blockage of the flow could also support the aspiration force of the distal catheter.
Also, in cases of M1 occlusion inflating the balloon may limit collateral flow to the ischemic area. Considering this, and as described by McTaggart et al., our strategy is to turn on distal aspiration prior to deployment of the stent retriever but only prior to removal of the stent the BGC is inflated and proximal aspiration is turned on.
To conclude we would like to thank McTaggart et al. for sharing their experience. In accordance with other recently published studies7 their work emphasize the need to reach high rates of TICI3 recanalization to maximize the likelihood of good clinical outcomes for our patients.
1. McTaggart RA, Tung EL, Yaghi S, et al. Continuous aspiration prior to intracranial vascular embolectomy (CAPTIVE): a technique which improves outcomes. Journal of NeuroInterventional Surgery; 2016:neurintsurg-2016-012838-012836
2. Velasco A, Buerke B, Stracke CP, et al. Comparison of a Balloon Guide Catheter and a Non–Balloon Guide Catheter for Mechanical Thrombectomy. Radiology; 2016:169-176
3. Nguyen TN, Malisch T, Castonguay AC, et al. Balloon Guide Catheter Improves Revascularization and Clinical Outcomes With the Solitaire Device: Analysis of the North American Solitaire Acute Stroke Registry. Stroke; 2013:141-145
4. Matsumoto H, Nishiyama H, Tetsuo Y, et al. Initial clinical experience using the two-stage aspiration technique (TSAT) with proximal flow arrest by a balloon guiding catheter for acute ischemic stroke of the anterior circulation. Journal of NeuroInterventional Surgery: British Medical Journal Publishing Group; 2016:neurintsurg-2016-012787-012786
5. Kowoll A, Weber A, Mpotsaris A, et al. Direct aspiration first pass technique for the treatment of acute ischemic stroke: initial experience at a European stroke center. Journal of NeuroInterventional Surgery; 2016:230-234
6. Chueh J-Y, Puri AS, Wakhloo AK, et al. Risk of distal embolization with stent retriever thrombectomy and ADAPT. Journal of NeuroInterventional Surgery; 2016:197-202
7. Dargazanli C, Consoli A, Barral M, et al. Impact of Modified TICI 3 versus Modified TICI 2b Reperfusion Score to Predict Good Outcome following Endovascular Therapy. American Journal of Neuroradiology: American Society of Neuroradiology; 2017:90-96
Giragani S et al. (published online 25 January 2017) described a remarkable case of recurrent transient ischemic attacks (TIA) due to carotid free floating thrombus. They successfully used stentriever with distal filter protection in retrieving the thrombus.
Here we share a similar case of TIA with right common carotid artery (CCA) floating thrombus that was effectively managed with distal filter protection and aspiration. A 48-year-male with recurrent ischemic symptoms detected to have right CCA long segment floating thrombus (approximately 4.5 cm) extending upto right proximal external carotid artery.* Under general anaesthesia through right femoral route long sheath guiding catheter (Neuron Max 6F088; Penumbra, Inc. Alameda, USA) was placed in right proximal CCA. After parking the filter device (Spider FX 6mm; eV3, Plymouth, Minnesota, USA) at distal cervical segment, thrombus was aspirated using penumbra system (5MAX ACE, 132 cm; Penumbra, Inc. Alameda, USA).* Final check angiography showed 80 % reduction in clot burden .*
Placing the filter protection device in the distal cervical segment does not protect thrombus migration to ECA, although it primarily prevent intracranial shower. In our index case thrombus fragment migrated to ECA, although it did not cause any neurological deficit. These cases highlight a novel technique to treat free floating thrombus.
With interest, I read this article and the authors' claim that their technique has not been previously described. A cursory search using PubMed would have shown that we described this approach almost 30 years ago:
Treatment of dural sinus thrombosis with local urokinase infusion. Case report. Scott JA, Pascuzzi RM, Hall PV, Becker GJ. J Neurosurg. 1988 Feb;68(2):284-7.
I was interested to read the paper by Yamauchi K and colleagues published in J Neurointerv Surg 2017 Sep. Hyperperfusion syndrome after carotid interventions has a low incidence but it can lead to morbidity and mortality. The aim of the authors was to evaluate the usefulness of quantitative DSA for predicting hyperperfusion phenomenon (HPP) after carotid artery stenting and angioplasty. Thirty-three consecutive patients with carotid stenosis treated with carotid artery stenting or angioplasty between February 2014 and August 2016 were included. The cerebral circulation time (CCT) was defined as the difference in the relative time to maximum intensity between arterial and venous regions of interest set on the angiograms. HPP was diagnosed straight after the procedure with qualitative 123I-IMP single-photon emission CT (SPECT). Cut-off points for detecting HPP for preprocedural CCT and periprocedural change of CCT were assessed by receiver operating characteristic analysis using 123I-IMP SPECT as reference standard. Differences between patients with and without HPP were analyzed by Student's t test for continuous variables and Fisher`s exact test for categorical variables. A p value of <0.05 was considered statistically significant. Receiver operating characteristic curve analysis of preprocedural CCT and ΔCCT was performed for the prediction of HPP, with 123I-IMP SPECT as standard of reference. They reported that the optimal cut-off points of preprocedural CCT and c...
Show MoreWe read with interest the recent paper looking at venous sinus pressure gradients prior to stenting (1), and commend the authors for their work on this interesting topic. We also share an interest in the subject, and recently published our experience looking at venous stenting in a similar patient population (2). The authors of the current paper documented significant differences in trans-stenotic venous pressure-gradients measured under general anaesthesia (GA), and suggested that pressure measurements should be performed with patients awake to counteract this. Another paper published in this issue of JNIS also documented the disparities between pressure measurements performed under GA versus those performed under conscious sedation (CS) (3). The pressure differences in our paper were significantly more marked in those patients who underwent measurements under local anaesthesia alone versus under CS. We can therefore hypothesise that even the use of CS can result in changes in the measured venous pressures in these patients, and indeed in the current paper the authors noted that the use of midazolam in their awake patients had a statistically significant effect on the pressures obtained. Since the decision to treat often hinges on this all-important measurement, we thus propose that venous sinus pressure measurements should be always performed using local anaesthesia alone, in an effort to minimise this variability.
1: Fargen KM, Spiotta AM, Hyer M, et al, Comparis...
Show MoreWe appreciate the interest shown by Drs. Yao and You (1) in our paper (2) and find it our pleasure to address their concerns.
The first point raised by Drs. Yao and You is that our search strategy missed two articles, namely those of Mortimer et al (2015) (3) and Morgan et al (1996) (4). We would like to reassure Drs. Yao and You that we did screen these articles, and decided against including them in our meta-analysis based on our inclusion criteria. The article by Mortimer et al (2015) (3) describes a patient population where balloon angioplasty, verapamil, and papaverine infusions were used separately or in various combinations. They did not break down their results by the specific intra-arterial vasodilator (IAD) used, and therefore we decided not to include this information. The paper by Morgan et al (1996) (4) describes a patient population which overlapped with that described by the same group in another paper, Morgan et al (2000) (5). We had personally communicated with the authors in 2016 regarding the multiple papers from this group, such as Little et al (1994) (6) and Morgan et al (2000)
(5) that described papaverine infusions for vasospasm. We found out that there were overlaps in these study populations, and that the cohort in the 2000 paper(5) was the most complete. Therefore, only this paper was included in our meta-analysis, while the earlier ones were excluded.
The second suggestion by Drs. Yao and You was to perform a regression ana...
Show MoreWith great interest, we read the article of Venkatraman et al.[1] published in the Journal of NeuroInterventional Surgery recently. They presented a comprehensive picture depicting the effect of intra-arterial vasodilators (IADs) on the vasospasm following aneurysmal subarachnoid hemorrhage. But we were concerned with several questions weakening the reliability and generalization of the meta-analysis.
Show MoreFirstly , though the detailed including criteria and searching strategy were provided in their meta-analysis, at least two eligible studies2,3 were missed which conformed to their including criteria and unfulfilled the excluding criteria. Two cohort studies of Morgan [2] and Mortimer [3] reported the effects of IADs on vasospasm with documentation of interested events, which should be included in Venkatraman’s analysis. Whether addition of these two studies could change the overall effect of IADs was unclear, but including any eligible study was in accordance with PRISMA principle.
Secondly, owing to the large number of included studies, the heterogeneity was substantial. Venkatraman et al.[1] conducted subgroup and sensitivity analyses, in which the heterogeneity remained significant (most values of I2 greater than 50%). It was rationale to turn to regression analyses in order to find and solve the heterogeneity.
Besides, this article included studies combining IADs with balloon angioplasty, which might overestimate effectiveness of IADs. IADs w...
We would like to thank Dr. Shotar and colleagues for their interest in our article. As highlighted by Dr. Shotar, delayed enhancing lesions (DEL) after coil embolization of aneurysm are suspected as a result of foreign body reaction 1-5. We agree with their opinion that the catheter coating of the inner wall of guiding catheter and/or the outer wall of microcatheter may be the source of foreign body. However, according to our experiences and analysis, it is our opinion that the coating material of the inner wall of microcatheter may also be the source.
Show MoreDr Shotar suggests that the distribution of the MR lesions in the territory of the parent artery (i.e.: ICA) in our series suggests the guiding catheter as the culprit. However, in all our cases 6, the aneurysms were located at the distal ICA (Ophthalmic artery, IC-anterior choroidal artery, superior hypophyseal artery). Thus, we believe that the distribution of the DELs on MR is not in conflict with our claim that the inner wall of the microcatheter is the source. Foreign body fragments from the microcatheter probably migrated into the aneurysmal sac during multiple coil introduction attempts under unusual friction and were swept downstream. Our benchtop analyses also support this finding.
Regarding Dr Shotar’s suggestion that "the patient treated with the microcatheter that showed coating fragments at the location of the friction on bench tests did not have DELs", this microcatheter was withdrawn imme...
To the Editor:
We read with great interest the article by McTaggart et al. on the new embolectomy technique called Continuous Aspiration Prior To Intracranial Vascular Embolectomy (CAPTIVE).(1) The paper adds information on the supporting evidence that a combined approach of stentretriever and aspiration-catheter utilization may be the optimal path in achieving higher rates of complete reperfusion in patients with large vessel occlusions.(2, 3) While the idea of starting aspiration with the intermediate catheter prior to and during the stentretriever placement is intriguing, attention has to be paid on the effect of prolonged aspiration on collateral flow, as reported in a recent JNIS publication.(4) Additionally, the ‘continuous’ part of the title may be misleading, as the authors state that they advance the aspiration-catheter towards the face of the clot until the drip rate has stopped. As seen in Fig 1E of the CAPTIVE publication, the tip of the aspiration-catheter becomes clogged with clot as ‘a portion is held captive within the distal aspiration catheter.’ This probably results in vacuum within the aspiration-catheter and non-existent aspiration in the vicinity of the aspiration-catheter tip during immobilization of the stentretriever/clot/aspiration-catheter unit. At last, the authors describe thoroughly a ‘De-CAPTIVE shear’ on Fig 2 but neglect to acknowledge that the same danger of clot-shearing applies to the moments of stentretriever/clot/aspiration-cath...
Show MoreTo the editor,
With great interest we read the recent paper by Martinez-Galdámez et al. regarding the periprocedural outcomes and early safety after placement of a Pipeline Embolization Device with Shield Technology (PEDshield) (1). Evaluation of new endovascular devices, such as PEDshield, is of the utmost importance to give future users a chance to objectively review possible benefits for their clinical practice.
In the study of Martinez-Galdámez et al. 76% of the target aneurysms were small (< 10 mm). It is known that small aneurysms are associated with a lower probability of thromboembolisms and ischemic stroke after flow diverter treatment than large and giant aneurysms (2,3). The size of the treated aneurysms, and not the PEDshield, might therefore explain the lack of thromboembolic complications reported in the study of Martinez-Galdámez et al. Selection bias might thus have led to the conclusion that the early safety of the PEDshield device is warranted.
Furthermore, it is hard to understand why only 21 out of 50 patients (42%) underwent platelet reactivity testing, especially since the primary outcome measure focused on identifying thromboembolic complications in the territory supplied by the treated artery. To make matters worse: when platelet reactivity tests revealed the presence of hyporesponders, anti-platelet therapy was left unchanged in most cases. If thromboembolic complications do occur in the 6-month and 1-year follow-up of this...
Show MoreWe have read with great interest the article describing the CAPTIVE technique for endovascular acute ischemic treatment by McTaggart et al.1. Firstly, we would like to commend the great clarity they used to describe the combination of distal aspiration and stent retriever to perform mechanical thrombectomy. Notably, they illustrated the rationale for aspiration prior to stent deployment as well as the removal of both distal aspiration catheter and stent as a single unit to decrease possible clot fragmentation.
We adopt a very similar approach for most of our cases, although we would like to emphasize a slight variant that appears clinically interesting.
In combination with stent retrievers, the balloon guide catheter (BGC) has been shown to improve the effectiveness of mechanical thrombectomy2, 3. In our experience, we typically use the CAPTIVE technique in association with a BGC which presents several potential advantages.
Show MoreFirstly, in cases of tortuous anatomy it provides excellent support for navigating the distal aspiration catheter. In addition, the balloon can be temporarily inflated at this stage to provide an anchoring effect in order to avoid potential push back of the guiding catheter4.
Secondly, McTaggart et al. reported 5% embolization to new territory with the CAPTIVE technique; an equivalent rate to previous reports on distal aspiration with no stent retriever5. In an in vitro study, Chueh et al.6 demonstrated a significant decrease o...
To the editor,
Giragani S et al. (published online 25 January 2017) described a remarkable case of recurrent transient ischemic attacks (TIA) due to carotid free floating thrombus. They successfully used stentriever with distal filter protection in retrieving the thrombus.
Here we share a similar case of TIA with right common carotid artery (CCA) floating thrombus that was effectively managed with distal filter protection and aspiration. A 48-year-male with recurrent ischemic symptoms detected to have right CCA long segment floating thrombus (approximately 4.5 cm) extending upto right proximal external carotid artery.* Under general anaesthesia through right femoral route long sheath guiding catheter (Neuron Max 6F088; Penumbra, Inc. Alameda, USA) was placed in right proximal CCA. After parking the filter device (Spider FX 6mm; eV3, Plymouth, Minnesota, USA) at distal cervical segment, thrombus was aspirated using penumbra system (5MAX ACE, 132 cm; Penumbra, Inc. Alameda, USA).* Final check angiography showed 80 % reduction in clot burden .*
Placing the filter protection device in the distal cervical segment does not protect thrombus migration to ECA, although it primarily prevent intracranial shower. In our index case thrombus fragment migrated to ECA, although it did not cause any neurological deficit. These cases highlight a novel technique to treat free floating thrombus.
*Representative image available.
With interest, I read this article and the authors' claim that their technique has not been previously described. A cursory search using PubMed would have shown that we described this approach almost 30 years ago:
Treatment of dural sinus thrombosis with local urokinase infusion. Case report. Scott JA, Pascuzzi RM, Hall PV, Becker GJ. J Neurosurg. 1988 Feb;68(2):284-7.
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