In vivo intraaneurysmal pressure measurements in experimental lateral wall aneurysms before and after onyx embolization

BACKGROUND

The aim of this study is to measure and compare the in vivo intraaneurysmal pressures of experimental lateral wall aneurysms, before and after onyx embolization. The data of this experiment will carry an important role in forming the scientific basis for the clinical endovascular applications.

MATERIALS AND METHODS

Five experimental lateral wall aneurysms were created by microsurgical techniques in 5 New Zealand rabbits' right common carotid arteries. Onyx embolization was applied to the aneurysms. Intraaneurysmal dome pressure and parent artery measurements before and after the procedure were recorded.

RESULTS

The mean arterial pressure recording in parent artery was 69.2 +/- 2.588 mm Hg under anesthesia. Mean heart rate was 131 beats per minute. The values were in physiologic limits. Meanwhile, aneurysm intradomal pressure recording showed a mean value of 59.2 +/- 5.069 mm Hg. Although there was incomplete occlusion of the aneurysm, intradomal mean pressure was recorded to be 24.4 +/- 8.876 mm Hg. After complete occlusion by onyx, mean intradomal aneurysm pressure was found to be 1.8 +/- 0.836 mm Hg.

DISCUSSION

This study is the first study reporting on intraaneurysmal pressure measurements before and after onyx embolization. The results in this experiment tend to show the adequate intraaneurysmal pressure control of onyx. This is important in the stabilization of the aneurysm to prevent rupture and rerupture. When compared with the findings of GDC coil, onyx embolization seems to be superior in intraaneurysmal pressure control.

CONCLUSION

In this study, it has been shown that onyx embolization decreases the intradomal aneurysmal pressure effectively.

Fibered electrolytically detachable platinum coils used for the endovascular treatment of intracranial aneurysms. Initial experiences and mid-term results in 474 aneurysms

SUMMARY

Between 1992 and 2003, a total of 2029 aneurysms in 1748 patients were treated by endovascular occlusion with electrolytically detachable coils. In this series, electrolytically detachable platinum coils with Nylon fibers (Sapphire Detachable Coil System, MTI, Irvine, CA, USA) were used in 474 aneurysms solely or in combination with bare coils from various manufacturers. To determine the safety and clinical efficacy of Nylon fibered coils for the endovascular treatment of intracranial aneurysms in comparison to bare platinum coils a thorough retrospective statistical analysis by means of logistic regression and matched pairs analysis was performed. Only treatments with data for all matching variables were used, resulting in 421 matched pairs. The analysis was performed with respect to clinical status and numerous parameters concerning individual aneurysm characteristics (e.g., location, neck width, fundus diameter). Treatment-related parameters included the use and percentage of fibered coils, occlusion rate, procedural complications, early clinical outcome and Glasgow Outcome Scale (GOS) scores. Finally, long-term follow-up results (particularly recurrence, cause of recurrence and post treatment haemorrhage) were evaluated. Both logistic regression and matched pairs analysis showed a statistically improved occlusion rate if fibered coils had been used (96% largely occluded with the use of fibered coils vs. 84-85% with the exclusive use of bare coils). However, the amount of fibered coils calculated as percentage of coil length did not seem to have significant impact. Procedures with fibered coils did not lead to a higher rate of thromboembolic events (8.0% for fibered vs. 10.5% for bare coils).The apparently better clinical outcome in the group treated with fibered coils determined by both postprocedural outcome and GOS, did not reach statistical significance. Analysis of the anatomical properties showed no differences between the groups treated with bare and fibered coils in terms of neck width, fundus diameter, and anatomic location. As expected, a higher occlusion rate was achieved in aneurysms with smaller neck and fundus independent from the type of coil used. On follow up angiography, there was an apparently lower rate of recurrence secondary to coil compaction in the group treated with fibered coils, but these data were compromised by the fact that up to date only about one third of 474 aneurysms treated with fibered coils had undergone angiographic follow-up and this did not reach statistical significance. From our experiences, we conclude that the use of fibered electrolytically detachable platinum coils in aneurysm treatment leads to significantly improved occlusion rates compared to the sole use of bare platinum coils. We hope that with increasing follow-up data we will be able to confirm that the apparently reduced recurrence rates for aneurysms treated with fibered coils can be proven with statistical significance.

In vitro and in vivo Studies of the Extent of Electrothrombotic Deposition of Blood Elements on the Surface of Electrolytically Detachable Coils

SUMMARY

Endovascular treatment of intracranial aneurysms with electrolytically detachable coils is often claimed to be based on electrothrombosis, i.e. intra-aneurysmal thrombus formation through applied direct current. Despite the fact that this concept was described more than a century ago, the significance of electrothrombosis in the endovascular treatment of aneurysms remains debatable. Apart from electrothrombosis, mechanical obliteration of the aneurysmal lumen might be one of the many possible mechanisms to explain why and how detachable coils are effective in preventing aneurysms from (re-)rupture. The purpose of this experimental study was to investigate to what extent direct current comparable to that used for coil detachment would influence the adhesion of cellular and liquid blood components to the surface of electrolytically detachable platinum coils. For the in vitro study, electrolytically detachable platinum coils of various types were exposed to stagnant heparinised blood for a total of 16 h, without or with applied direct current for 30 or 90 s (1 mA, 4-6 V, coil as anode). For the in vivo study, electrolytically detachable platinum coils were exposed to flowing blood for 180 s, without or with applied direct current (2 mA, 4-6 V, coil as either anode or cathode), without anti-coagulation and after intravenous administration of 5000 U Heparin and again after the intravenous administration of 500 mg Aspisol in addition to Heparin. After exposure to blood according to these different experimental protocols, the coils were fixed in formalin solution, gold coated and examined by scanning electron microscopy. Thrombus formation on the surface of all unfibred coils was thin and highly variable both from coil to coil, and on different areas of any given coil. The application of direct current minimally enhanced thrombus formation in stagnant blood in vitro, but not in vivo. The cellular and fibrin adhesions on the coil surfaces without and with applied current did not effectively increase the diameter or volume of unfibred coils. Coils with attached nylon fibres, however, proved to be highly thrombogenic without or with application of current. In fibred coils, surface adhesions without and with applied current were voluminous enough to effectively increase the diameter of the coil, potentially important for the process of endosaccular aneurysm occlusion. Electrothrombosis plays no role in the endovascular treatment of intracranial aneurysms with electrolytically detachable coils. This explains why platinum coils with non-electrolytic detachment mechanisms show a similar efficiency and recurrence rate.

The Underlying Mechanisms of Endovascular Exclusion of Intracranial Aneurysms by Coils. How Important is Electrothrombosis?

SUMMARY

Endovascular coil treatment of intracranial aneurysms is now widely accepted. We discuss some of the arguments for the relative roles of electrothrombosis, spontaneous thrombosis, mechanical filling, haemodynamic effects and surface properties in successful coil treatment. Despite an enormous body of literature, with many theories and much data, there is limited evidence for, or understanding of, the mechanisms by which coil treatment protects against aneurysm rupture. It seems likely that electrothrombosis plays no part.Dense packing is probably important in preventing recurrence. New technologies aiming to encourage endothelialisation and increased connective tissue formation appear promising.

Clinical and angiographic results of endosaccular coiling treatment of giant and very large intracranial aneurysms: a 7-year, single-center experience

OBJECTIVE

To evaluate whether the objectives of surgical treatment, i.e., prevention of aneurysmal rebleeding, relief of aneurysmal mass effect, and prevention of embolic complications, are met by endosaccular coiling treatment applied to giant and very large wide-necked aneurysms.

METHODS

Thirty patients with 31 giant or very large aneurysms were considered to show unacceptable risk/benefit ratios for open surgery and were treated using the Guglielmi detachable coil (GDC) method between 1992 and 1998.

RESULTS

With endosaccular GDC treatment, 73.3% of the population experienced excellent to good recoveries (Glasgow Outcome Scale scores of 4 or 5), with a 13.3% procedure-related morbidity rate and a 6.7% procedure-related mortality rate. Two hemorrhaging episodes occurred after GDC treatment (annual bleeding rate, 2.5%; 2 hemorrhaging episodes/79.2 patient-yr). Symptoms related to aneurysmal mass effect were improved for 45.5% of the patients presenting with signs of neural compression. Among 23 patients with 24 aneurysms who were available for angiographic follow-up assessment, complete or nearly complete occlusion was observed for 17 aneurysms (71%; angiographic follow-up period, 24.3 +/- 19.6 mo, mean +/- standard deviation). A single total embolization served as definitive treatment for only 12.5% of the giant aneurysms and 31% of the very large aneurysms.

CONCLUSION

Endosaccular GDC treatment of giant and very large aneurysms was accomplished with procedure-related morbidity and mortality rates comparable to those for open surgery performed by experts. However, because coil stability was unsatisfactory, we suggest that the GDC method should currently be reserved for individuals who are considered poor candidates for open surgery.

Acute histologic and ultrastructural study in one case of human basilar tip aneurysm embolised with guglielmi detachable coils

SUMMARY

Histologic findings after Guglielmi detachable coils endovascular embolisation have been studied in experimental aneurysms. Few reports describe histopathologic reactions to platinum coils in humans. In this report we describe gross, light microscopic pathology and scanning electron microscopy study of a ruptured basilar tip artery aneurysm in a patient who died 16 hours following coiling.

Gross and microscopic histopathological findings in aneurysms of the human brain treated with Guglielmi detachable coils

OBJECT

The histopathological characteristics of aneurysms obtained at autopsy or surgery 3 days to 54 months after being treated with Guglielmi detachable coils (GDCs) were assessed.

METHODS

Seventeen aneurysms were obtained at autopsy and one was removed at surgery. Fourteen were examined histologically with the coils in situ. Naked coils embedded in an unorganized thrombus were found in those aneurysms that had been treated with coils within 1 week earlier. An incomplete replacement of the intraluminal blood clot by fibrous tissue and a partial membranous covering at the aneurysm orifice were observed in those aneurysms that had been treated with coils between 2 and 3 weeks prior to examination. One small aneurysm treated 6 weeks before harvesting showed formation of an endothelium-lined layer of connective tissue at the orifice. Collagen-rich vascularized tissue surrounding the coils was found in an aneurysm removed at surgery 54 months after coil implantation. Interestingly, six (50%) of 12 aneurysms (two small, three large, and one giant) that had been deemed 100% occluded on initial angiography showed tiny open spaces between the coils at the neck on gross examination.

CONCLUSIONS

Endothelialization of the aneurysm orifice following placement of GDCs can occur; however, it appears to be the exception rather than the rule. In large aneurysms the process of intraaneurysm clot organization seems to be delayed and incomplete; tiny open spaces between the coils and an incomplete membranous covering in the region of the neck are frequently encountered. Further longitudinal studies are required to establish the spectrum of healing profiles that may direct our efforts in modifying the GDC system to produce a more stable long-term result.