Hydrophilic polymer-coated guide wire combined with progressive suppleness pursil catheter for safer, more definitive embolisation of arteriovenous malformations

History of surgery for cerebrovascular disease in children. Part III. Arteriovenous malformations

✓ Arteriovenous malformations (AVMs) are the most common cause of intracerebral hemorrhage in children. In this paper the authors trace the historical evolution of the recognition, diagnosis, and treatment of pediatric intracerebral AVMs, and they summarize the contemporary approach and current controversies surrounding treatment of these lesions. Important distinctions between adult and pediatric AVMs are emphasized.

Preoperative portal vein embolization with a new liquid embolic agent

PURPOSE

To evaluate the effectiveness and safety of a new liquid embolic agent in preoperative portal vein embolization.

MATERIALS AND METHODS

Embol-78 was obtained by means of hydrolysis of polyvinyl acetate and was dissolved in a mixture of ethanol and nonionic water-soluble contrast medium. After percutaneous puncture of the portal vein, embolization of the right portal vein was performed in 22 patients with hepatocellular carcinoma and in 29 patients with nonhepatocellular carcinoma. In each group, changes in volume of the future liver remnant, portal venous pressure, and liver enzymes were evaluated both before and after embolization. Complications were also evaluated.

RESULTS

Portal vein embolization was successful in all patients, without major complications. The mean volumes of the future liver remnant before and 2 weeks after embolization were 385 mL +/- 138 and 533 mL +/- 140, respectively, in the hepatocellular carcinoma group and 517 mL +/- 348 and 755 mL +/- 197, respectively, in the nonhepatocellular carcinoma group. There were only transient elevations in liver enzyme levels after embolization. Mean portal venous pressures before and after the procedure were 16.7 mm Hg +/- 3.8 and 20.3 mm Hg +/- 3.6, respectively, in the hepatocellular carcinoma group and 11.7 mm Hg +/- 3.5 and 14.6 mm Hg +/- 3.6, respectively, in the nonhepatocellular carcinoma group. In each group, changes in volume of the future liver remnant and portal venous pressure were statistically significant (P <.001).

CONCLUSION

The liquid embolic material Embol-78 seems to be effective and safe for preoperative portal vein embolization.

Combined embolization and microsurgery for cerebral arteriovenous malformation

Thirty-seven of 396 patients with arteriovenous malformations (AVMs) were treated by preoperative embolization and surgical excision in our medical center between 1991 and 1997. The AVMs were Spetzler-Martin grade I in six, grade II in 11, grade III in 12, grade IV in four, and Grade V in four. A total of 69 embolization procedures were performed using estrogen alcohol and polyvinyl acetate as liquid embolization materials. AVM grades improved following embolization in 10 patients. Three hemorrhages occurred several days after the final embolization, probably due to hemodynamic stress on the unoccluded perforating feeders or drainer occlusion. Surgical resection was performed under guidance of intraoperative digital subtraction angiography. Although the AVMs were excised totally in one stage with no major neurological deficits, normal perfusion pressure breakthrough occurred in a patient with prominent collateral circulation of the AVM which developed after the main feeder embolization. Preoperative staged embolization with estrogen alcohol and polyvinyl acetate is effective to expand the surgical indication and to achieve complete resection of difficult AVMs. Direct surgery should be performed as soon as possible if hemodynamic changes are observed following embolization.

An evaluation of the Physical Properties of Current Microcatheters and Guidewires. The Development of the "Catheter-glide Approach" in Response to Weaknesses of Current Materials

SUMMARY

The physical properties of the 16 microcatheters and 7 guidewires currently available were evaluated to assess their manoeuvrability. This investigation included the latest varieties of these products. The test results showed that there was a wide variation in flexibility and friction between the distal segments of the catheters. Even the recently developed hydrophilic polymer-coated catheters show this variation. Comparisons between guidewires also showed differing degrees of flexibility and friction. Torque transmission was also a variable factor. A combination of the most flexible microcatheter with the lowest friction and the most responsive guidewire with the lowest friction was picked for clinical evaluation. The effectiveness and safety of this combination of equipment was proved by embolising various cerebral arteriovenous malformations( AVMs) and thrombolysing cerebral emboli of arteriosclerotic patients. However it remains difficult to reach the nidus of distally located AVMs with extremely long and tortuous feeding pedicles such as parietal lobe AVMs. The efforts to overcome the weaknesses of current materials by further improving equipment and technique is another subject of the current paper.

Portal vein embolization with use of a new liquid embolic material: an experimental study

PURPOSE

To evaluate the efficacy and safety of a new liquid embolic material in portal vein embolization (PVE).

MATERIALS AND METHODS

A new embolic material (Embol) was percutaneously injected into the left portal vein of 13 swine, using a balloon catheter to prevent reflux. The swine were killed immediately (n = 6), 2 weeks (n = 4), and 4 weeks (n = 3) after the PVE, and the volumes of the right and left lobes were measured. The changes in body temperature, aspartate aminotransferase (AST) (formerly SGOT), alanine aminotrasferase (ALT) (formerly SGPT), and bilirubin levels after the PVE were studied, and the histopathologic changes in the embolized and nonembolized lobes were examined with light microscopy.

RESULTS

The average volume ratio of the right:left lobe immediately after the PVE was 55(+/-2):45(+/-1), and changed to 71(+/-3):29(+/-3) at 2 weeks and 82(+/-3):18(+/-3) at 4 weeks after embolization. There were only mild changes in AST, ALT, and bilirubin levels, and only one pig showed a significant elevation in body temperature after PVE. Microscopically, the embolized lobe showed contraction of hepatocyte without any sign of necrosis and the nonembolized lobe expansion of hepatocyte.

CONCLUSIONS

The new embolic material seems effective and safe for PVE.

Materials and biomaterials for interventional radiology

Devices used in interventional radiology have significantly developed in the past few years. In order to understand the trends of this development, we analyzed how new interventional devices are progressively incorporating materials having original physical properties, and how developers are today progressively turning towards biomaterials, with respect to the new regulatory environment, and the requirements of biocompatibility.