Angioscopy: a new light on peripheral vascular disease

High-Resolution Scanning Fiber Angioscopy as an Adjuvant to Fluoroscopy During Endovascular Interventions

PURPOSE

To demonstrate the feasibility and potential utility of high-resolution angioscopy during common endovascular interventions.

METHODS

A 3.7-F scanning fiber angioscope was used in 6 Yorkshire pigs to image branch vessel selection, subintimal dissection, wire snaring, and stent placement. The angioscope was introduced in a coaxial fashion within a standard 6-F guide catheter. A clear field of view was provided using continuous heparinized saline flush through the outer guide catheter. The flush flow rate was manually adjusted to provide clear imaging depending on the diameter of the vessel and local blood flow conditions.

RESULTS

The scanning fiber angioscope was compatible with off-the-shelf catheters and devices commonly used in peripheral and aortic interventions. Video-rate, high-resolution images were obtained during all the interventions tested and provided information that was complementary to simultaneously acquired fluoroscopy. The scanning fiber angioscope was able to detect subintimal dissection and branch vessel stent coverage with higher resolution than fluoroscopy alone.

CONCLUSION

Endoluminal imaging with the scanning fiber angioscope is feasible with current endovascular devices and provides additional relevant information that cannot be assessed fluoroscopically. The scanning fiber angioscope represents a novel optical platform on which new endovascular techniques may be developed that will minimize radiation and contrast doses for patients.

High-resolution angioscopic imaging during endovascular neurosurgery

BACKGROUND

Endoluminal optical imaging, or angioscopy, has not seen widespread application during neurointerventional procedures, largely as a result of the poor imaging resolution of existing angioscopes. Scanning fiber endoscopes (SFEs) are a novel endoscopic platform that allows high-resolution video imaging in an ultraminiature form factor that is compatible with currently used distal access endoluminal catheters.

OBJECTIVE

To test the feasibility and potential utility of high-resolution angioscopy with an SFE during common endovascular neurosurgical procedures.

METHODS

A 3.7-French SFE was used in a porcine model system to image endothelial disruption, ischemic stroke and mechanical thrombectomy, aneurysm coiling, and flow-diverting stent placement.

RESULTS

High-resolution, video-rate imaging was shown to be possible during all of the common procedures tested and provided information that was complementary to standard fluoroscopic imaging. SFE angioscopy was able to assess novel factors such as aneurysm base coverage fraction and side branch patency, which have previously not been possible to determine with conventional angiography.

CONCLUSION

Endovascular imaging with an SFE provides important information on factors that cannot be assessed fluoroscopically and is a novel platform on which future neurointerventional techniques may be based because it allows for periprocedural inspection of the integrity of the vascular system and the deployed devices. In addition, it may be of diagnostic use for inspecting the vascular wall and postprocedure device evaluation.

Angioscopy in vascular surgery: the state of the art

Although angioscopy is considered by many vascular surgeons to be a valuable clinical tool, others view it as expensive and unnecessary. To better define the appropriate role for angioscopy in vascular surgery, a critical review of the recent literature was undertaken. Angioscopy allows more complete valvulotomies with fewer endothelial injuries when preparing autogenous veins to be used as arterial conduits, and results in more complete thromboembolectomy of native arteries and grafts. Angioscopy can replace completion arteriography in infrainguinal arterial reconstructions with an equivalent clinical outcome. Angioscopy may be useful in the assessment of carotid endarterectomy, femoral vein valve repair, and pulmonary embolectomy. It has been useful in various research applications. The rate of complications is less than 1%. Angioscopy is of benefit in preparing veins to be used as arterial conduits and in performing thromboembolectomy. In some circumstances it can replace intraoperative arteriography. Other applications await further validation. The risks of angioscopy are acceptably low.

Infragenicular in situ vein bypass graft occlusion: a multivariate risk factor analysis

Early postoperative thrombosis and the later development of graft stenoses are the two major causes of vein bypass graft failure. The risk factors for both these outcomes were analysed in a multivariate analysis of 82 consecutive infragenicular in situ vein grafts. Twenty-four grafts failed within 30 days but eight were successfully revised. Technical errors accounted for six of the failures. A multivariate analysis revealed graft resistance > 1.4 peripheral resistance units (odds ratio 5.8, 95% C.I. 1.6-20) as the only independent risk factor for early graft failure. Eighteen grafts (27%) developed a stenosis most commonly in the distal third of the graft (46%). Poor quality, small diameter vein was the only independent risk factor for graft stenosis (odds ratio 7, 95% C.I. 1.5-34). Composite vein grafts, where narrowed and thickened vein had been replaced, had a significantly lower stenosis rate (difference in proportions 0.41, 95% C.I. 0.1-0.8, Mann-Whitney U test).

Infrainguinal vein graft stenosis

Although knowledge of the biological processes involved in the development of intimal hyperplasia has increased markedly in recent years, the precise aetiology of infrainguinal vein graft stenosis remains undetermined. Current therapy is therefore directed at treatment of the established lesion rather than its prevention. There seems little doubt, however, that recent advances in understanding of the vascular biology of normal and pathological saphenous vein will eventually lead to specific targeted therapy that will allow the prevention of vein graft stenosis.