Utility of intravascular ultrasound in intracranial and extracranial neurointerventions: experience at University at Buffalo Neurosurgery-Millard Fillmore Gates Circle Hospital

Applications of a Novel Microangioscope for Neuroendovascular Intervention

BACKGROUND AND PURPOSE

Visualization in neuroendovascular intervention currently relies on biplanar fluoroscopy and contrast administration. With the advent of endoscopy, direct visualization of the intracranial intravascular space has become possible with microangioscopes. We analyzed the efficacy of our novel microangioscope to enable direct observation and inspection of the cerebrovasculature, complementary to a standard fluoroscopic technique.

MATERIALS AND METHODS

Iterations of microangioscopes were systematically evaluated for use in neurodiagnostics and neurointerventions in both live animal and human cadaveric models. Imaging quality, trackability, and navigability were assessed. Diagnostic procedures assessed included clot identification and differentiation, plaque identification, inspection for vessel wall injury, and assessment of stent apposition. Interventions performed included angioscope-assisted stent-retriever thrombectomy, clot aspiration, and coil embolization.

RESULTS

The microangioscope was found helpful in both diagnosis and interventions by independent evaluators. Mean ratings of the imaging quality on a 5-point scale ranged from 3.0 (clot identification) to 4.7 (Pipeline follow-up). Mean ratings for clinical utility ranged from 3.0 (aspiration thrombectomy) to 4.7 (aneurysm treatment by coil embolization and WEB device).

CONCLUSIONS

This fiber optic microangioscope can safely navigate and visualize the intravascular space in human cadaveric and in vivo animal models with satisfactory resolution. It has potential value in diagnostic and neurointerventional applications.

Co-registration of Intravascular Ultrasound With Angiographic Imaging for Carotid Artery Disease

BACKGROUND

Intravascular ultrasound (IVUS) provides endoluminal views and cross-sectional images of carotid arteries but lacks overview of vascular territory provided by angiography. Co-registration of IVUS with angiographic images may provide the potential to navigate both imaging modalities in a synchronous manner. The objective of this study is to evaluate the feasibility and accuracy of co-registering both imaging modalities in the carotid vasculature of the neck.

METHODS

Fourteen patients with 15 cervical carotid artery lesions underwent angiography and subsequent treatment. In each case, an IVUS catheter was advanced to the target lesion and a reference angiography sequence was acquired. This was followed by an electrocardiography-triggered fluoroscopy sequence that was initiated upon IVUS catheter pullback. IVUS data collected during pullback were registered with fluoroscopy and evaluated for error and clinical usability.

RESULTS

A total of 32 landmarks were identified that demonstrated reasonable agreement during IVUS-angiography co-registration. There was a mean registration error distance of 3.36 mm (SD 2.82 mm) between targets. The longitudinal extent and severity of the disease through the target segment could be easily evaluated after co-registration.

CONCLUSION

Semiautomatic tracking and co-registration of angiography and IVUS is a new technology and has the potential to increase the use of IVUS in carotid disease and to proivde the opportunity to optimize procedural outcomes.

Utility of Intravascular Ultrasound During Carotid Angioplasty and Stenting with Proximal Protection

Carotid artery stenting (CAS) is an established treatment for patients at high-risk for endarterectomy. Patients who undergo CAS have been shown to have periprocedural microembolic events on transcranial Doppler ultrasonography. Flow reversal is often applied in these situations to prevent distal emboli and concurrently allow blood to flush into the common carotid artery. Patients who demonstrate soft plaque morphology that may embolize distally during CAS benefit from flow reversal. Even so, the all-stroke risk in these patients is nearly 1.4%. High-risk patients typically have more difficult plaque morphology; flow reversal decreases the rate of distal emboli but does not offer the intraprocedural visualization seen with intravascular ultrasound (IVUS). In this paper, we illustrate potential periprocedural outcomes associated with stenting of the stenotic carotid bifurcation under flow reversal and how IVUS influenced endovascular management. Three high-risk patients who underwent CAS with direct common carotid artery cutdown approaches due to common carotid ostia disease with flow-reversal proximal embolic protection also had intraprocedural IVUS performed to evaluate plaque morphology and stability before the protection system was removed. Case 1 illustrates no intraluminal thrombus on IVUS, requiring no further intervention after stent placement. Case 2 demonstrates intraluminal thrombus on IVUS requiring a second stent to stabilize plaque. Case 3 shows the inadequate resolution of thrombus after a second stent, which was addressed with balloon angioplasty. In our experience, using IVUS as an adjunct to CAS under proximal embolic protection helped demonstrate plaque morphology and plaque fragmentation after stent placement. These cases illustrate the potential benefit of allowing stabilization of the plaque before flow reversal is stopped.

A new set of eyes: development of a novel microangioscope for neurointerventional surgery

BACKGROUND

Endovascular technological advances have revolutionized the field of neurovascular surgery and have become the mainstay of treatment for many cerebrovascular pathologies. Digital subtraction angiography (DSA) is the 'gold standard' for visualization of the vasculature and deployment of endovascular devices. Nonetheless, with recent technological advances in optics, angioscopy has emerged as a potentially important adjunct to DSA. Angioscopy can offer direct visualization of the intracranial vasculature, and direct observation and inspection of device deployment. However, previous iterations of this technology have not been sufficiently miniaturized or practical for modern neurointerventional practice.

OBJECTIVE

To describe the evolution, development, and design of a microangioscope that offers both high-quality direct visualization and the miniaturization necessary to navigate in the small intracranial vessels and provide examples of its potential applications in the diagnosis and treatment of cerebrovascular pathologies using an in vivo porcine model.

METHODS

In this proof-of-concept study we introduce a novel microangioscope, designed from coherent fiber bundle technology. The microangioscope is smaller than any previously described angioscope, at 1.7 F, while maintaining high-resolution images. A porcine model is used to demonstrate the resolution of the images in vivo.

RESULTS

Video recordings of the microangioscope show the versatility of the camera mounted on different microcatheters and its ability to navigate external carotid artery branches. The microangioscope is also shown to be able to resolve the subtle differences between red and white thrombi in a porcine model.

CONCLUSION

A new microangioscope, based on miniaturized fiber optic technology, offers a potentially revolutionary way to visualize the intracranial vascular space.

Imaging Inflammation in Cerebrovascular Disease

Imaging inflammation in large intracranial artery pathology may play an important role in the diagnosis of and risk stratification for a variety of cerebrovascular diseases. Looking beyond the lumen has already generated widespread excitement in the stroke community, and the potential to unveil molecular processes in the vessel wall is a natural evolution to develop a more comprehensive understanding of the pathogenesis of diseases, such as ICAD and brain aneurysms.

Endovascular Advances for Extracranial Carotid Stenosis

Carotid artery stenting has become a viable alternative to carotid endarterectomy in the management of carotid stenosis. Over the past 20 years, many trials have attempted to compare both treatment modalities and establish the indications for each one, depending on clinical and anatomic features presented by patients. Concurrently, carotid stenting techniques and devices have evolved and made endovascular management of carotid stenosis safe and effective. Among the most important innovations are devices for distal and proximal embolic protection and new stent designs. This paper reviews these advances in the endovascular management of carotid artery stenosis within the context of the historical background.

Role of stenting for intracranial atherosclerosis in the post-SAMMPRIS era

Introduction. The initial promise of endovascular stenting for the treatment of intracranial atherosclerotic disease (ICAD) has been tempered by the results of the SAMMPRIS trial which demonstrated better outcomes with medical management compared to stenting for symptomatic ICAD. We review post-SAMMPRIS ICAD stenting outcomes. Methods. A comprehensive literature search was performed using PubMed to identify all ICAD stenting series published after the SAMMPRIS in September 2011. The type and design of the stent, number of patients and lesions, inclusion criteria, and clinical and angiographic outcomes were noted. Results. From October 2011 to August 2013, 19 ICAD stenting series were identified describing the interventional outcomes for 2,196 patients with 2,314 lesions. Of the 38 different stents used, 87% were balloon-expandable stents (BESs) and 13% were self-expanding stents. The median minimum stenosis was 50%. The median rates of technical success rate, postprocedural ischemic events, and symptomatic in-stent restenosis (ISR) were 98% (range 87–100%), 9.4% (range 0–25%), and 2.7% (range 0–11.1%), respectively. The median follow-up durations were one to 67 months. Conclusions. The management of severe ICAD remains controversial. Future trials are needed to define the optimal patient, lesion, and stent characteristics which will portend the best outcomes with intervention.

Perioperative Complications After Carotid Artery Stenting

BACKGROUND:

Technological advances have resulted in diminishing perioperative complications reported during carotid artery stenting (CAS) trials. Because trial experience lags behind technological advances, an understanding of the incidence of perioperative complications after CAS remains in flux.

OBJECTIVE:

In this single-arm, observational study, a contemporary experience of CAS at a high-volume academic training center for neuroendovascular surgeons was reviewed to assess perioperative morbidity.

METHODS:

A prospectively maintained database of all neuroendovascular procedures was queried for all CAS procedures performed for stenotic atherosclerotic disease between 2009 and 2011. Each case was assessed for major perioperative (30 day) adverse events, including new acute ischemic stroke, postoperative symptomatic intracranial hemorrhage, myocardial infarction (MI), and mortality.

RESULTS:

A total of 474 patients were identified. Perioperative adverse events were noted in 13 patients (2.7%). These included 4 ischemic strokes, 4 intracranial hemorrhages, 3 MIs, and 5 deaths. Most perioperative events occurred in symptomatic patients (10 of 239 symptomatic patients with events, 4.2% event incidence), whereas these events occurred rarely in asymptomatic patients (3 of 235 asymptomatic patients with events, 1.3% event incidence).

CONCLUSION:

In this retrospective analysis of consecutive patients treated with CAS, the perioperative incidence of stroke (0.9%), MI (0.6%), and death (1.1%) was favorable.

Off-label use of drugs and devices in the neuroendovascular suite

SUMMARY

The off-label use of drugs and devices in neuroendovascular procedures is common. Neurointerventionalists should be well aware of the level of evidence available in support of the off-label use of drugs and devices in their practice and some of the potential adverse events associated with them. These uses are categorized as I or II if they have been evaluated as primary or ancillary interventions in prospective trials/registries of neuroendovascular procedures and III if they were evaluated in case series. Category IV use is based on evaluation as primary or ancillary interventions in prospective trials/registries of non-neuroendovascular procedures. Physicians are allowed to use off-label drugs and procedures if there is strong evidence that they are beneficial for the patient. The neurointerventional professional societies agree that off-label use of drugs and devices is an important part of the specialty, but practicing providers should base their decisions on sound evidence when using such drugs and devices.