Vertebral artery origin stent placement with distal protection: technical and clinical results

OBJECTIVE

To report the feasibility, safety, and 1-month results of performing stent placement for vertebral origin stenosis with the use of a distal protection device. Distal protection devices have been shown to reduce the number of cerebral emboli and subsequent ischemic events when used as adjuncts to percutaneous carotid intervention; however, one case of the use of a distal protection device for vertebral artery has been reported in the literature.

METHODS

We retrospectively determined rates of technical success and 1-month stroke or death associated with stent placement by using distal protection (Filter EX; Boston Scientific, Natick, Mass) in patients with symptomatic vertebral artery origin stenosis. Technical success was defined as successful deployment of distal protection device and stent at target lesion followed by successful retrieval of the device and a final residual stenosis of less than 30%. Other outcomes ascertained included any stroke, death, and semiquantitative assessment of particulate material retained by the filter device.

RESULTS

The mean age of the 12 treated patients was 68 years (range, 52-88 years) and the group included 9 men and 3 women. The mean percentage of vertebral artery origin stenosis was 71 +/- 6%. Femoral and radial approaches were used in 9 and 3 cases, respectively. Technical success was achieved in 11 of the 12 patients in whom distal protection device placement was attempted. Postprocedure residual stenosis was 5 +/- 4%. Eight devices held macroscopically visible embolic debris (large and small amounts in 3 and 5 devices, respectively). No stroke or death was observed in the 1-month follow-up.

CONCLUSION

The present study demonstrates the feasibility of performing stent placement for vertebral artery origin stenosis by using a distal protection device. Further studies are required to determine the effectiveness of this approach for vertebral artery origin atherosclerosis.

Is IV tissue plasminogen activator beneficial in patients with hyperdense artery sign?

OBJECTIVE

To evaluate the effect of IV recombinant tissue plasminogen activator (rt-PA) in patients with hyperdense artery sign (HAS) on initial CT scan.

METHODS

The authors determined the differential effect of IV rt-PA (0.9 mg/kg) in patients with HAS by testing the interaction of rt-PA and HAS in a logistic regression model after adjusting for age, sex, initial NIH Stroke Scale score (NIHSSS), time to randomization, systolic blood pressure, serum glucose, body temperature, and rt-PA in 616 patients treated within 3 hours of symptom onset. Outcomes evaluated included intracranial hemorrhage, modified Rankin scale (mRS) 0-1, Barthel Index (BI) of > or = 95, Glasgow Outcome Scale (GOS) of 0-1, NIHSSS 0-1, and death at 90 days.

RESULTS

HAS was detected on the initial CT scan in 91 (15%) of the 616 patients by an independent neuroradiologist. Significantly lower rates of mRS 0-1, BI > or = 95, GOS of 0-1, or NIHSSS 0-1 at 90 days were observed among patients with HAS. IV rt-PA significantly increased the rates of mRS 0-1, BI > or = 95, GOS of 0-1, or NIHSSS 0-1 at 90 days after adjusting for potential confounders without any significant modifying effect (interaction) of HAS. Among the 91 patients with HAS, rt-PA use demonstrated a trend or significance for increased adjusted rates of favorable outcomes by mRS (p = 0.04), BI (p = 0.1), GOS (p = 0.03), and NIHSSS (p = 0.01).

CONCLUSION

Although hyperdense artery sign is associated with poor outcome, IV recombinant tissue plasminogen activator may be beneficial in this subgroup of patients with ischemic stroke.

Comparison of 1- and 2-marker techniques for calculating system magnification factor for angiographic measurement of intracranial vessels

BACKGROUND AND PURPOSE

Accurate estimation of an intracranial vessel size is crucial during a diagnostic or therapeutic angiography procedure. The use of 1 or 2 external markers of known size is previously proposed to manually estimate the magnification factor (MF) of an intracranial vessel. The authors evaluated the use of different external marker techniques commonly used during angiographic measurements.

METHODS

Forty-three intracranial vessels in 17 patients were measured using 1-and 2-marker techniques. To obtain the MF, 2 metallic markers were attached to the frontal-temporal regions. The MFs for the targeted vessels were obtained from the x-ray films by measuring the image sizes of the markers and their positions with respect to the target vessel.

RESULTS

Using a phantom, the errors resulted from (a) linear interpolation of MFs, (b) linear interpolation of inverse MFs, and (c) using the MFs of 1 marker, which were 1.23% to 2.23%, 0.8% to 1.55%, and 3.85% to 14.62%, respectively. A similar trend was observed for the measurement of cerebral arteries.

CONCLUSION

The use of 2 markers can result in a more accurate estimation of the vessel size. The use of only 1 external marker can lead to substantial error based on the location of the target vessel. Optimizing image acquisition is also crucial for accurate determination of vessel size.

Determination of blood flow velocity and transit time in cerebral arteriovenous malformation using microdroplet angiography

Advancement in imaging and biomedical technology has improved the use of catheter-based transarterial embolization (occlusive therapy) of cerebral arteriovenous malformations (AVMs). Among a variety of embolic agents, liquid adhesives (acrylates) have proven to be more successful in permanent obliteration of AVMs. The use of liquid adhesives requires the experience and skill of the operator. However, acquiring accurate information on blood flow and transit times through the AVM prior to embolization can optimize the treatment. In addition, knowledge of the polymerization time and behavior of the acrylate enables a complete and safe occlusion of the arteriovenous transition within the AVM nidus. Standard commercially available iodine-based contrast agents seem to be insufficient to determine AVM transit times from angiograms. For a more accurate assessment of AVM transit times, the use of a nonsoluble contrast agent (Ethiodol) and a high-speed digital subtraction angiography (DSA) is suggested. Small amounts (<20 microl) of Ethiodol were infused to create microdroplets and traced using DSA at 15 fps. Transit time, defined as the time interval required for a droplet to reach the venous part of the AVM after being flushed from the tip of the catheter, could be accurately calculated. Postprocessing was used to calculate trajectories and velocities of microdroplets.

Modification of a previously described arteriovenous malformation model in the swine: endovascular and combined surgical/endovascular construction and hemodynamics

BACKGROUND AND PURPOSE

The rete mirabile in swine has been proposed as an arteriovenous malformation (AVM) model for acute experimental studies through surgical creation of a large carotid-jugular fistula. This report describes two endovascular modifications to simplify the surgical creation and provides hemodynamic parameters for the AVM model.

METHODS

An AVM model was created in 29 animals to study n-butyl 2-cyanoacrylate polymerization kinetics. The common carotid artery (CCA) was punctured and a guiding catheter was inserted tightly into the origin of the ascending pharyngeal artery (APA). The CCA was ligated proximal to the catheter to create a pressure drop across the rete, which represented the AVM nidus. The catheter hub was opened whenever needed and served as the venous drainage of the AVM nidus. The contralateral APA served as the arterial feeder. Instead of the surgical ligation of the CCA, a temporary balloon occlusion was performed in three animals.

RESULTS

A mean pressure gradient of 14.9 +/- 10.5 mm Hg (range, 4-42 mm Hg) was measured across the rete. The mean flow rate was 30.4 +/- 14.2 mL/min (range, 3.5-46 mL/min), as measured at the venous drainage.

CONCLUSION

The endovascular and combined surgical-endovascular rete AVM model in swine is easy to construct and is less time-consuming than are the currently used models for acute experimental studies. Hemodynamic parameters can be monitored during the entire experiment and correspond to values found in human cerebral AVMs.

Microdroplet tracking using biplane digital subtraction angiography for cerebral arteriovenous malformation blood flow path and velocity determinations

High-speed biplane angiography is used to determine the path and velocity of microdroplets of contrast material in three dimensions. By allowing more accurate determination of detailed blood flow in feeding vessels and draining veins of cerebral arteriovenous malformations than available with standard angiography, the new method offers the potential for more accurate treatment and further study of neurovascular/cerebrovascular hemodynamics. The first study of the method is presented.