Detection and characterization of very small cerebral aneurysms by using 2D and 3D helical CT angiography.
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Aneurysm, Ruptured↗
Biomedical subjects
David F Kallmes
Publications and source records attributed to David F Kallmes.
A collagen-based coil for embolization of saccular aneurysms in a New Zealand White rabbit model.
BACKGROUND AND PURPOSE: In the treatment of cerebral aneurysms, platinum coils often fail to elicit a fibrotic response. We tested the hypothesis that a new, collagen-based endovascular coil would improve angiographic and histologic outcomes as compared with those achieved with platinum coils in a rabbit model of saccular aneurysms. METHODS: Elastase-induced aneurysms were created in 12 New Zealand White rabbits (body weight, 3-4 kg). Embolization was performed either by use of collagen-based coils (n = 6) or platinum coils (n = 6). In both coil groups, subjects were kept alive for either 2 weeks (n = 3 [collagen], n = 3 [platinum]) or 10 weeks (n = 3 [collagen], n = 3 [platinum]) after embolization and then were sacrificed. Digital subtraction angiography (DSA) was performed immediately after embolization and immediately before sacrifice. Postmortem histologic analysis of all coils was performed. RESULTS: Collagen-based coils were loosely packed in all cases because of limitations in size of coils available for embolization. In all six aneurysms packed with collagen-based coils, progressive thrombosis was noted at follow-up (DSA). Platinum coil samples were densely packed in all six cases. Progressive thrombosis was seen in one case, and interval regrowth was present in one case. Two weeks after embolization, collagen-based coil samples showed a marked peri-coil cellular response. Ten weeks after embolization, collagen-based samples had dense connective tissue matrix deposition in two of three cases. Platinum coils had unorganized thrombus at 2 weeks; loose-matrix deposition was only seen in the 10-week samples. Smooth muscle actin-positive cells were seen across the neck of the aneurysm in four of six collagen-based coil cases. CONCLUSION: Collagen-based coils show a marked cellular response in animal-model aneurysms, with resultant high rates of progressive occlusion after embolization. Dense matrix deposition is commonly seen with collagen-based coils. This contrasts with low rates of progressive thrombosis and high rates of loose matrix deposition seen with platinum coils.
Angiography, Digital Subtraction↗
Bone morphogenetic protein gene therapy.
STUDY DESIGN: A retrospective analysis of previous BMP gene therapy and general gene therapy publications. OBJECTIVE: To present the potential role of BMP gene therapy for the induction of osteogenesis and spinal fusion. SUMMARY OF BACKGROUND DATA: A variety of viral and non-viral techniques have been utilized to insert foreign transgenes into cells, both in vivo and in vitro. These techniques are now being used to transduce cells with a BMP gene to express significant amounts of BMP. This secreted BMP can subsequently stimulate osteogenesis in a variety of locations, including in the paraspinal regions. METHODS: A retrospective analysis of the literature. RESULTS: Direct and ex vivo BMP gene therapy has been shown to successfully promote bone healing and regeneration in a variety of animal models. Long-term and regulated transgene expression are clear advantages of BMP gene delivery, compared to direct BMP application. To date, BMP gene delivery with adenoviral vectors have been the most effective approach for stimulating bone induction in vivo. CONCLUSIONS: Although BMP gene therapy techniques have significant potential for the treatment of spine pathology, further preclinical and clinical research and development are required before this technology will have direct clinical applications.
Animals↗
Ectopic osteogenesis using adenoviral bone morphogenetic protein (BMP)-4 and BMP-6 gene transfer.
Bone morphogenetic proteins (BMPs) delivered on scaffolds can induce ectopic bone formation after subcutaneous injection. Adenoviral vectors (Ad) carrying BMP2, BMP7, and BMP9 cDNAs have been shown to produce bone through endochondral ossification. The present study was performed to elucidate the histological events leading to ectopic ossification for two novel first-generation adenoviral constructs encoding BMPs, AdBMP4 and AdBMP6. In vitro, the viral constructs produced and secreted the mature BMP4 and BMP6 proteins. In vivo, the calf muscles of athymic nude rats were injected with AdBMP4, AdBMP6, AdBMP2, or AdlacZ. Rats were sacrificed 3, 6, 9, 16, 21, 60, and 90 days postinjection. Whereas AdBMP4 produced ectopic bone through mechanisms similar to endochondral ossification, AdBMP6 seemed to induce bone by way of mechanisms similar to both intramembranous and endochondral ossification pathways. At the relatively low vector dose used in this study, AdBMP2 caused an initial recruitment of primitive mesenchymal cells, without further development to bone. From computed tomographic analysis, AdBMP6 produced the most rapid tissue calcification. The ultimate density of ectopic bone formed by AdBMP4 and AdBMP6 was comparable. The current study demonstrates that AdBMP4 and AdBMP6 are more potent than the prototypical osteogenic adenoviral vector AdBMP2 and seem to induce ectopic bone by different mechanisms.
Adenoviridae↗
Lack of preoperative spinous process tenderness does not affect clinical success of percutaneous vertebroplasty.
PURPOSE: Some operators use the lack of point tenderness over compression fractures to exclude patients from undergoing percutaneous vertebroplasty procedures. The purpose of this study was to determine whether this lack of tenderness portends a poorer clinical outcome after vertebroplasty than is achieved in patients with such tenderness. MATERIALS AND METHODS: The authors conducted a retrospective review of consecutive percutaneous vertebroplasty procedures performed at their institution to define two populations. Group 1 included 90 patients with tenderness to palpation over the spinous process of the fractured vertebra, whereas group 2 included 10 patients without such tenderness. This second group presented with back pain and demonstrated tenderness distant from the fracture (n = 5), tenderness lateral to the fracture (n = 4), or no focal tenderness at all (n = 1). All were treated because of edema seen on magnetic resonance (MR) imaging and/or increased activity on bone scan. Clinical outcomes were assessed by quantitative measurements of pre- and postoperative levels of pain (11-point scale) and mobility (five-point scale). RESULTS: Pain improvement of three points or greater occurred in 77 of the 85 patients (91%) in group 1 who complied with follow-up and nine of nine such patients (100%) in group 2, with mean postoperative pain levels of 1.82 and 0.33 points, respectively (P =.14). Forty of 45 patients (89%) in group 1 with impaired preoperative mobility reported improvement postoperatively, as did two of three such patients (67%) in group 2. Mean levels of postoperative impaired mobility for groups 1 and 2 were 0.27 and 0.67 points, respectively (P =.27). CONCLUSION: Pain on palpation over the fractured vertebra is not a necessary requirement in selecting patients who will benefit from percutaneous vertebroplasty. Other factors, such as MR evidence of edema or increased uptake on bone scan, should be weighed considerably in the decision to treat a patient.
Aged↗
CT and radionuclide study of BMP-2 gene therapy-induced bone formation.
RATIONALE AND OBJECTIVES: Gene therapy techniques have the potential to treat numerous diseases, from cancer to diabetes. One promising application is the use of bone morphogenetic protein (BMP) gene transfer to induce bone formation. Previous studies have demonstrated that both direct and ex vivo BMP gene therapy have the capacity to initiate the normal endochondral pathway, leading to rapid mature bone formation. In the present study, computed tomography (CT) and radionuclide imaging was used to assess bone formation induced by BMP gene therapy accurately and noninvasively. MATERIALS AND METHODS: Athymic nude rodents were treated with 1.25 x 10(10) particles of adenovirus-BMP-2 (Ad-BMP-2) (treatment group) or adenovirus-beta-gal (control group). At various intervals after treatment, the animals underwent CT, planar digital radiography, and planar radionuclide scintigraphic imaging. RESULTS: Radionuclide scintigraphy clearly demonstrated active bone deposition that began as early as 15 days after treatment and peaked at approximately 36 days, only at the Ad-BMP-2 injection sites. CT clearly demonstrated ectopic bone induction over time at the Ad-BMP-2 treatment sites, in perfect correlation with the scintigraphic findings. CONCLUSION: This study clearly illustrates that gene therapy-induced osteogenesis can be studied with multimodality imaging and supports the use of these approaches in future preclinical and clinical studies.
Adenoviridae↗
Ex vivo bone morphogenetic protein-9 gene therapy using human mesenchymal stem cells induces spinal fusion in rodents.
OBJECTIVE: Ex vivo gene therapy with the use of human mesenchymal stem cells (hMSCs) and bone morphogenetic protein (BMP) genes provides a local supply of precursor cells and a supraphysiological dose of osteoinductive molecules that may promote bone formation in patients with inadequate hMSC populations because of age, osteoporosis, metastatic bone disease, iatrogenic depletion, or other metabolic derangements. This study was undertaken to evaluate the efficacy of ex vivo gene therapy with the use of hMSCs and the BMP-9 gene to promote spinal fusion in the rat. METHODS: Sixteen athymic nude rats were treated with hMSCs transduced with recombinant, replication-defective Type 5 adenovirus containing the cytomegalovirus promoter and either the BMP-9 (Ad-BMP-9) or the beta-galactosidase (Ad-beta-gal) gene. Ad-beta-gal served as the control. Each animal received a percutaneous, paraspinal injection of 10(6) hMSCs transduced with 50 plaque-forming units/cell adenovirus in the lumbar region, with Ad-BMP-9 on the left and Ad-beta-gal on the right. At 8 weeks postinjection, computed tomographic scans of the lumbosacral spine were obtained, and the lumbosacral spine specimens were examined histologically. RESULTS: Both computed tomographic studies and histological analysis clearly demonstrated large volumes of ectopic bone at the Ad-BMP-9-transduced hMSC injection sites, resulting in successful spinal fusion and no evidence of nerve root compression or local or systemic toxicity. The contralateral regions that were treated with Ad-beta-gal-transduced hMSCs showed no evidence of osteogenesis. CONCLUSION: The results of this study suggest that hMSC and BMP-9 ex vivo gene therapy may be useful in inducing spinal fusion as well as other related procedures and certainly warrants further clinical development.
Animals↗
Unilateral transpedicular percutaneous vertebroplasty: initial experience.
PURPOSE: To compare the radiographic and clinical outcomes of a unipediculate approach with those of standard bipediculate vertebroplasty. MATERIALS AND METHODS: Retrospective review of percutaneous vertebroplasties yielded 18 vertebrae in 17 patients that were treated with a standard bipediculate approach and 57 vertebrae in 32 patients that were treated with a modified unipediculate approach. Anteroposterior radiographs obtained after the procedure were viewed to calculate the percentage of cement opacification in both vertebral halves, and mean values were compared between uni- and bipediculate approaches by using a two-tailed Student t test. Clinical outcomes, including pain relief and change in pain medication requirements, were compared in the two groups by using the chi(2) or Fisher exact test. RESULTS: With the unipediculate approach, filling across the midline was achieved in 55 (96%) of 57 injections. Mean opacification of vertebral body halves was 83% +/- 19 (SD) and 77% +/- 16 for the bipediculate and unipediculate approaches, respectively (P =.19). Among patients with available follow-up data, 16 (94%) of 17 patients who underwent the bipediculate procedure and 28 (88%) of 32 patients who underwent the unipediculate procedure achieved adequate pain relief (P =.65) with mean decreases in pain severity of 7.3 +/- 3.1 and 6.6 +/- 2.9, respectively. CONCLUSION: Use of a unipediculate approach in percutaneous vertebroplasty allows filling of both vertebral halves from a single puncture site with no statistically significant difference in clinical outcome from that of bipediculate vertebroplasty.
Aged↗
Elastase-induced saccular aneurysms in rabbits: a dose-escalation study.
BACKGROUND AND PURPOSE: Reproducible animal models facilitate preclinical assessment of aneurysm therapies. Our purpose was to determine if increased elastase doses enlarge aneurysms and parent arteries. METHODS: Rabbit right common carotid artery (CCA) aneurysms were created with distal ligation and intraluminal elastase incubation. Groups were 1) sham (no elastase, n = 3), 2) 25% elastase (10 minutes, n = 9), 3) 50% elastase (10 minutes, n = 7), and 4) 50% elastase (20 minutes, n = 41). Angiography was performed after 14 days. Resultant aneurysm width and height and parent artery diameters were measured and compared with the Student t or Mann-Whitney (Wilcoxon rank sum) test. RESULTS: Proximal segments were enlarged in all elastase subjects and no sham subjects. Mean measurements were significantly smaller in the sham group than in other groups. Aneurysm widths and heights, respectively, were 3.8 mm +/- 0.8 and 7.4 mm +/- 2.0 in the low-dose group; 3.9 mm +/- 1.3 and 8.5 mm +/- 3.8, medium-dose group; and 4.1 mm +/- 1.1 and 8.7 mm +/- 2.6, high-dose group. Differences were not significant. Parent artery widths were 3.5 mm +/- 0.7, 3.8 mm +/- 0.7, and 4.3 mm +/- 1.4 in the low-, medium-, and high-dose groups, respectively; the high-dose group had larger arteries (P =.07). CONCLUSION: Aneurysms were reliably created and were sized similar to human intracranial aneurysms. Elastase concentration and incubation duration did not affect resultant size. Relatively short incubation (eg, 10 minutes) and 25% elastase can be used to create rabbit aneurysms, especially if dilatation of adjacent parent arteries is to be avoided.
Angiography, Digital Subtraction↗
Relevance of antecedent venography in percutaneous vertebroplasty for the treatment of osteoporotic compression fractures.
BACKGROUND AND PURPOSE: Controversy exists regarding the utility of antecedent venography in percutaneous vertebroplasty. Our purpose was to determine whether antecedent venography improves clinical outcomes and/or decreases extravertebral cement extravasation in these procedures. METHODS: We retrospective reviewed outcomes of consecutive percutaneous vertebroplasty procedures performed at our institution to define two populations, each consisting of 24 patients treated at 42 vertebral levels. Group 1 included patients who underwent antecedent venography, and group 2 included patients treated without venography. Clinical outcomes were assessed with quantitative measurements of pain and mobility. Venograms and postprocedural radiographs were interpreted to evaluate the number of vertebrae with extravertebral cement extravasation, degree of extravasation at each level, and correlation between venography and vertebroplasty. RESULTS: Pain improved in 19 of 20 group 1 patients, compared with 21 of 22 group 2 patients; mean postoperative pain levels were 1.3 and 1.8, respectively (P =.50), on a scale of 0 (no pain) to 10 (worst pain). All 11 group 1 patients with impaired preoperative mobility reported postoperative improvement, as did all 12 group 2 patients; mean levels of postoperative impaired mobility for groups 1 and 2 were 0.35 and 0.27, respectively (P =.43). Twenty-two of 42 vertebrae treated in group 1 demonstrated extravasation, compared with 28 of 42 in group 2 (P =.266); amounts of extravasation did not differ. Among 22 levels of extravasation in group 1, venograms in 14 showed correlative extravasation. CONCLUSION: Antecedent venography does not significantly improve the effectiveness or safety of percutaneous vertebroplasty performed by qualified, experienced operators.
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Cardiovascular effects of polymethylmethacrylate use in percutaneous vertebroplasty.
BACKGROUND AND PURPOSE: Previous investigators have described an association between polymethylmethacrylate (PMMA) use in hip arthroplasty and cardiovascular derangement. Our purpose was to evaluate the effects of PMMA injection on patient vital signs during percutaneous vertebroplasty. METHODS: We retrospectively reviewed patient charts at our institution to gather blood pressure, heart rate, and arterial oxygen saturation data for the following time points: before, during, 5 minutes after, and 10 minutes after PMMA injection during percutaneous vertebroplasty. These data were obtained for 142 injections (78 patients), and preinjection vital signs were compared with vital signs during and after PMMA injection. Multivariable regression modeling was used to ascertain the effects of cardiopulmonary comorbidities on vital signs. RESULTS: Mean arterial blood pressure and heart rate during, 5 minutes after, and 10 minutes after PMMA injection were not significantly different from their respective preprocedure values (P =.19-.92). Values for oxygen saturation during PMMA injection and 5 minutes thereafter were not significantly different from preprocedure values (P =.80 and.89, respectively). Oxygen saturation was significantly lower at 10 minutes after injection than before injection (P =.007), although the mean difference was negligible (0.6%). CONCLUSION: We find no generalized association between PMMA injection during percutaneous vertebroplasty and systemic cardiovascular derangement.
Aged↗
Vertebroplasty in the mid- and upper thoracic spine.
BACKGROUND AND PURPOSE: Vertebroplasty performed in the mid- and upper thoracic spine presents technical challenges that differ from those in the lower thoracic and lumbar region. We herein report results of percutaneous vertebroplasty for treatment of painful, osteoporotic compression fractures in the mid- and upper thoracic spine. METHODS: Retrospective chart review identified vertebroplasty treatments performed for painful osteoporotic compression fractures at T4-T8. The following were catalogued: percentage of vertebral body compression, needle size, surgical approach, clinical outcome, volume of cement injected, and complications. RESULTS: Sixty-three vertebral bodies were treated in 41 patients. Mean percentage of compression was 44%. Bipediculate injections were used in 12 (19%) of 63 treatment levels, and unipediculate injections were used in 51 (81%) of treatments (75 injections performed). Eleven-gauge needles were used for 55 (73%) of the 75 injections, and 13-gauge needles were used for 20 (27%). Clinical follow-up was available for 76% of the patients. Mean pre- and postoperative pain intensity was 9.7 +/- 1.0 and 1.7 +/- 1.9, respectively (P <.0001). Mean pre- and postoperative medication scores were 3.4 +/- 0.7 and 1.7 +/- 1.7, respectively (P =.075). Fracture involving the pedicle used for needle access was noted in one (1.3%) of 75 injections; this pedicle had been traversed using a 13-gauge needle. Staphylococcus epidermidis infection occurred in one case. No cases of pneumothorax were noted. CONCLUSION: Transpedicular vertebroplasty is readily and safely performed using 11-gauge needles in the mid- and upper thoracic regions, yielding excellent pain relief and low complication rates.
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Healing response in elastase-induced rabbit aneurysms after embolization with a new platinum coil system.
BACKGROUND AND PURPOSE: Elastase-induced rabbit aneurysms offer promise in preclinical testing, but their radiographic and histologic features after dense packing with platinum coils are unknown. We evaluated these features by using a new platinum coil system. METHODS: Right common carotid arterial (CCA) aneurysms were created in 17 rabbits by distal ligation and intraluminal elastase incubation. At least 3 weeks later, aneurysms were packed with detachable platinum coils. Animals were sacrificed at 2 (group 1, n=4), 4 (group 2, n=5), 12 (group 3, n=4), or 24 (group 4, n=4) weeks. Aneurysmal occlusion and coil compaction were angiographically assessed. Histologic features of tissue covering the coils and the aneurysmal dome were assessed and semiquantitatively compared across groups. RESULTS: No notable tracking, deployment, or detachment problems occurred. Volumetric occlusion was 5-49% (mean, 26.8% +/- 11%). Angiographic occlusion was 100% in six cases, 95% in four, and 90% in seven; occlusion scores remained unchanged in 13 cases, decreased in one, and increased in two (one case excluded from angiographic follow-up). Histologic findings were concordant within groups. Group 1 had coverage with thin fibrin layers and scattered leukocytes; group 2, some spindle-cell coverage; group 3, spindle-cell coverage. In groups 1 and 2, dome findings included only unorganized blood products. In group 3, blood products had been replaced with a hypocellular, poorly staining matrix. Some group 4 subjects had variably aged blood products, with tissue of limited organization. CONCLUSION: The platinum coil system performed well in experimental aneurysmal embolization. Densely packed rabbit aneurysms demonstrate reproducible histologic evolution: early fibrin coverage, delayed spindle-cell coverage, delayed intraaneurysmal thrombus resorption, and occasional coil compaction.
Animals↗
Thrombus formation at the neck of cerebral aneurysms during treatment with Guglielmi detachable coils.
BACKGROUND AND PURPOSE: Thromboembolic events are a common source of complications during Guglielmi detachable coil (GDC) treatment of intracranial aneurysms. Thrombus formation at the coil-parent artery interface is not commonly reported but is an important potential source of emboli. We describe nine cases in which thrombus propagated from GDCs into the parent artery during coil therapy of cerebral aneurysms and subsequent treatment of the thrombus. METHODS: A retrospective review of a procedural database was performed to identify cases in which thrombus occurred during GDC treatment of cerebral aneurysms during a 30-month period. All images were reviewed at the time of the procedure. Nine cases of thrombus forming at the coil-parent artery interface and five cases of distal emboli were identified among 210 cases. All patients underwent anticoagulation with heparin during GDC treatment procedures. RESULTS: Thrombus was identified at the coil-parent artery interface during GDC treatment in nine (4.3%) of 210 cases. In each case, the thrombus was recognized before distal embolic complication occurred and was successfully treated with heparin alone (five patients) or with heparin plus a glycoprotein IIb-IIIa inhibitor (four patients). CONCLUSION: Potential clinical complications can be avoided by early recognition of thrombus at the coil-parent artery interface and by administering appropriate medical therapy.
Abciximab↗
New expandable hydrogel-platinum coil hybrid device for aneurysm embolization.
This study introduces a new, hybrid embolic device that in addition to offering all the important attributes of existing detachable platinum coils also shows an enhanced ability to fill aneurysm cavities. The device consists of a carrier platinum coil coupled to an expandable hydrogel material, which undergoes a ninefold increase in volume when placed into a physiological environment. Distinct from previous devices aimed at speeding the organization of thrombus, the new device has been designed to entirely fill the aneurysm cavity, with complete or near-complete exclusion of thrombus. Unlike thrombus, the hydrogel material is stable and unaffected by natural thrombolytic processes and thus may diminish observed rates of aneurysm recanalization. We report the angiographic and histologic findings of the new, hybrid device used to treat experimental aneurysms in rabbits.
Angiography, Digital Subtraction↗
The therapeutic benefit of repeat percutaneous vertebroplasty at previously treated vertebral levels.
BACKGROUND AND PURPOSE: Recurrent pain after vertebroplasty is relatively common, usually representing a new fracture at a different vertebral level. In a small cohort described herein, clinical and imaging findings indicated that recurrent pain arose from abnormality of the previously treated level. Our purpose was to demonstrate that repeat percutaneous vertebroplasty performed within the same fractured vertebra can offer therapeutic benefit for patients with recurrent pain after initial treatment. METHODS: We conducted a retrospective review of consecutive vertebroplasty procedures performed at our institution to define a patient population that underwent repeat vertebroplasty for recurrent pain at previously treated vertebral levels. We identified six such patients over an 8-year period, and clinical outcomes were assessed through quantitative measurements of pre- and postoperative levels of pain and mobility. RESULTS: Initial vertebroplasty resulted in substantial improvement in pain in all six patients. Patients developed recurrent pain between 8 days and 167 days after initial vertebroplasty. After repeat vertebroplasty, five of the six patients reported a reduction of at least 3 points in their rating of pain, with a mean reduction of 6.5 points and a mean postoperative pain level of 3.5 points (11-point scale). Four of six patients reported impaired mobility before repeat vertebroplasty, and all four demonstrated a postoperative improvement in mobility. Mean increase in mobility was 1.50 points, and the mean postoperative mobility impairment was 0.25 points (5-point scale). CONCLUSION: The clinical outcomes of the patients within this case series suggest that repeat percutaneous vertebroplasty performed at previously treated vertebral levels for recurrent pain offer therapeutic benefit.
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Assessment of the interventional neuroradiology workforce in the United States: a review of the existing data.
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Cerebrovascular Disorders↗
Cerebral aneurysm perforations complicating therapy with Guglielmi detachable coils: a meta-analysis.
BACKGROUND AND PURPOSE: The risk of intraprocedural aneurysm perforation in patients with previously ruptured aneurysms tends to be higher than that of patients with previously unruptured aneurysms, but a statistically significant difference has not been shown. Our purpose was to define the rates of occurrence and of morbidity and mortality associated with aneurysmal perforation associated with coil embolization. METHODS: A meta-analysis of the results from 17 published retrospective reports of aneurysm perforations complicating therapy with Guglielmi detachable coils (GDCs) was performed. Rates of perforation and associated morbidity and mortality in previously ruptured and unruptured aneurysms were calculated. The mechanism of perforation was noted. RESULTS: The risk of intraprocedural perforation was significantly higher in patients with ruptured aneurysms compared with patients with unruptured aneurysms (4.1% vs 0.5%; P <.001). The combined risk of permanent neurologic disability and death associated with intraprocedural aneurysm perforation was 38% for ruptured aneurysms and 29% for unruptured aneurysms. The morbidity and mortality rates with perforations caused by coils (39%) and microcatheters (33%) were similar. The morbidity and mortality rate for microguidewire perforations was considerably lower (0%, n = 4) than the rates for coils and microcatheters, but number of cases was too low to indicate statistical significance. CONCLUSION: The risk of aneurysm perforation during GDC therapy is much higher in patients with previously ruptured aneurysms than in those with unruptured aneurysms. The morbidity and mortality rates are substantial for perforations caused by coils and microcatheters, whereas they seem to be much lower for perforations caused by microguidewires.
Aneurysm, Ruptured↗