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.

The endoscopic no-touch saphenous vein harvesting technique.

The no-touch saphenous vein harvesting technique is being increasingly used; however, this technique causes more leg wound complications than conventional techniques. Endoscopic saphenous vein harvesting is considered a safe and effective approach for reducing leg complications, despite the fact that experience with this technique remains limited, because leg CO2 insufflation and dissection with a tip cannula to isolate the vein enables the graft to naturally skeletonize.  In this video tutorial, we demonstrate our endoscopic no-touch saphenous vein harvesting technique using a reusable saphenous vein retractor system without CO2 insufflation and an electrothermal bipolar vessel sealing device.

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.

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.

Detection of vulnerable atherosclerotic plaque during thoracic endovascular aortic repair using nonobstructive angioscopy.

An angioscope was used to observe the intima of the aorta in an 82-year-old patient who had undergone thoracic endovascular aortic repair. The aortic angioscopic findings showed vulnerable plaques from the ascending aorta to the aortic arch that had not been visualized using preoperative computed tomography. After deploying a stent graft from zone 1 to zone 4, the proximal edge of the stent graft was adjacent to the ruptured plaque with mixed thrombi. In spite of these findings, the patient had an uneventful recovery. Angioscopy may have the potential to stratify the risk of thoracic endovascular aortic repair-related complications.

Improving the visual field in coronary artery by with non-obstructive angioscopy: dual infusion method.

Non-obstructive angioscopy (NOA) is used to visualize the surface of the coronary artery, and a clear visual field is obtained by injecting transparent fluid into the gap between the probing catheter and the fiber. This study examines visual field expansion by a dual infusion method, which involves an infusion from the probing and guiding catheters, and the relationships between visual grade and vessel characteristics. Thirty-two patients and thirty patients performed coronary plaque analysis with NOA using the conventional method and the novel dual infusion method, respectively. Images were blindly analyzed retrospectively. Visual fields were assessed from image slices using a 5-point scale (0 = invisible, 1 = poor, 2 = adequate, 3 = good, 4 = excellent) at 5-s intervals. The relationships between visual grade and vessel characteristics were analyzed using multiple stepwise linear regression analysis. The mean visual grade, "excellent" ratio, and "adequate" ratio were significantly higher using the dual infusion method than those obtained using the conventional method (p = 0.003, p = 0.004, and p = 0.005 respectively). The "invisible" ratio was significantly lower using the dual infusion method than the conventional method (p = 0.027). The visual field was negatively associated with the conventional method (ß â€Š= -0.154, p < 0.001), large vessels (ß = -0.004, p < 0.49), bifurcation (ß  = -0.205, p < 0.001), vessels with a sharp angle (ß  = -0.106, p < 0.001), in-stent (ß = -0.180, p < 0.001), and distal border of stent (ß  = -0.075, p < 0.001); and positively associated with significant stenosis (ß â€Š= 0.072, p < 0.001) and significantly covered stents (ß â€Š= 0.050, p = 0.018). The visual field with NOA can be effectively expanded by the dual infusion method.

Angioscopic observation in chronic thromboembolic pulmonary hypertension before and after balloon pulmonary angioplasty.

: We here report the angioscopic assessment of inoperable peripheral chronic thromboembolic pulmonary hypertension in an 81-year-old man who was previously diagnosed with the disease. To assess the pathological morphology of the web lesion, pouch defect and band lesion, we used two types of angioscopic catheter: blood flow-maintaining type and blood flow-blocking type. Angioscopy revealed a heterogeneous thrombus that contained white organized thrombus, red fragile thrombus and yellowish thrombus. After three sessions of balloon pulmonary angioplasty, his pulmonary arterial pressure decreased and his symptom of dyspnea on exertion and desaturation were improved. Angioscopy displayed various forms of organized thrombus, and also allowed the detailed observation of lesions that were difficult to be observed by angiography.

[An Experimental Set-Up for Navigated-Contrast-Agent and Radiation Sparing Endovascular Aortic Repair (Nav-CARS EVAR)]. / Ein Prototyp für die navigierte Implantation von Aortenstentprothesen zur Reduzierung der Kontrastmittel- und Strahlenbelastung: Das Nav-CARS-EVAR-Konzept (Navigated-Contrast-Agent and Radiation Sparing Endovascular Aortic Repair).

INTRODUCTION: Over the last decade endovascular stenting of aortic aneurysm (EVAR) has been developed from single centre experiences to a standard procedure. With increasing clinical expertise and medical technology advances treatment of even complex aneurysms are feasible by endovascular methods. One integral part for the success of this minimally invasive procedure is innovative and improved vascular imaging to generate exact measurements and correct placement of stent prosthesis. One of the greatest difficulty in learning and performing this endovascular therapy is the fact that the three-dimensional vascular tree has to be overlaid with the two-dimensional angiographic scene by the vascular surgeon. MATERIAL AND METHODS: We report the development of real-time navigation software, which allows a three-dimensional endoluminal view of the vascular system during an EVAR procedure in patients with infrarenal aortic aneurysm. We used the preoperative planning CT angiography for three-dimensional reconstruction of aortic anatomy by volume-rendered segmentation. At the beginning of the intervention the relevant landmarks are matched in real-time with the two-dimensional angiographic scene. During the intervention the software continously registers the position of the guide-wire or the stent. An additional 3D-screen shows the generated endoluminal view during the whole intervention in real-time. RESULTS: We examined the combination of hardware and software components including complex image registration and fibre optic sensor technology (fibre-bragg navigation) with integration in stent graft introducer sheaths using patient-specific vascular phantoms in an experimental setting. From a technical point of view the feasibility of fibre-Bragg navigation has been proven in our experimental setting with patient-based vascular models. Three-dimensional preoperative planning including registration and simulation of virtual angioscopy in real time are realised. CONCLUSION: The aim of the Nav-CARS-EVAR concept is reduction of contrast medium and radiation dose by a three-dimensional navigation during the EVAR procedure. To implement fibre-Bragg navigation further experimental studies are necessary to verify accuracy before clinical application.

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.

Cannulation of the internal carotid artery in mice: a novel technique for intra-arterial delivery of therapeutics.

We have developed a novel minimally invasive technique for the intra-arterial delivery of therapeutics to the mouse brain. CD-1 mice were anesthetized and placed in a lateral decubitus position. A 10mm midline longitudinal incision was made over the thyroid bone. The omohyoid and sternomastoid muscles were retracted to expose the common carotid artery and external carotid artery (ECA). To maximize delivery of administered agents, the superior thyroid artery was ligated or coagulated, and the occipital artery and the pterygopalatine artery (PPA) were temporarily occluded with 6-0 prolene suture. The ECA was carefully dissected and a permanent ligature was placed on its distal segment while a temporary 6-0 prolene ligature was placed on the proximal segment in order to obtain a flow-free segment of vessel. A sterilized 169 µm outer diameter polyimide microcatheter was introduced into the ECA and advanced in retrograde fashion toward the carotid bifurcation. The catheter was then secured and manually rotated so that the microcatheter tip was oriented cephalad in the internal carotid artery (ICA). We were able to achieve reproducible results for selective ipsilateral hemispheric carotid injections of mannitol mediated therapeutics and/or gadolinium-based MRI contrast agent. Survival rates were dependent on the administered agent and ranged from 78 to 90%. This technique allows for reproducible delivery of agents to the ipsilateral cerebral hemisphere by utilizing anterograde catheter placement and temporary ligation of the PPA. This method is cost-effective and associated with a low rate of morbimortality.

Endovascular treatment of distal internal carotid artery occlusions with retrievable stents.

BACKGROUND: Acute stroke due to distal intracranial internal carotid artery (ICA) occlusion has a poor natural history. Outcome in patients who receive intravenous tissue plasminogen activator (tPA) is also unsatisfactory. The objective of this study is to evaluate the effectiveness and safety of endovascular treatment with retrievable stents in these patients. METHODS: Data from a prospective register of patients with acute stroke treated with an endovascular procedure in a single centre were analysed. RESULTS: A total of 20 patients with distal ICA occlusion were collected. Mean baseline National Institutes of Health Stroke Scale score was 18. Eight cases (40%) had received previous intravenous tPA. Mean time from stroke to recanalization was 393 min. Retrievable stents with proximal occlusion and aspiration were used in all cases. In 3 patients, 2 retrievable stents were used simultaneously. Complete recanalization (thrombolysis in cerebral infarction 2b/3) was accomplished in 85% of cases. A favourable clinical outcome (modified Rankin Scale score 0-2) was achieved in 13 patients (65%). Mortality occurred in 2 cases (10%). CONCLUSIONS: Endovascular treatment of patients with distal ICA occlusion seems safe and effective. Retrievable stents may be the treatment of choice, although randomized clinical trials are necessary. The use of 2 retrievable stents at the same time could be an alternative technique useful in thrombi of larger size.

Vascular microanastomosis through an endoscopic approach: feasibility study on two cadaver forearms.

The size of the incisions for free muscle flaps is often very large, and a source of deep adhesions and unaesthetic scars. But it is justified by performing the microsurgical step comfortably. In the hopes of shortening the size of incisions, the goal of this work was to study the feasibility of vascular microanastomoses through an endoscopic approach. The material consisted of two cadavers, a telemanipulator, and a vascular clamp. The antebrachial skin was detached then distended by gas insufflation. Four incisions, 1cm each, allowed the insertion of four trocarts connected to the telemanipulator. The artery was dissected (radial or ulnar) and the vascular clamp was introduced under the skin through one of the trocarts, and then installed on the dissected artery. The vascular anastomosis was performed with the use of a 10/0 nylon suture. The anastomosis lasted 2 hours under insufflation without any leak. The two arteries were identified then dissected without difficulty. The anastomosis was performed in good conditions. The assembling and disassembling of the clamp were time consuming. The main difficulties were caused by a long suture and a very fragile needle. Our results demonstrate the feasibility of vascular microanastomosis through an endoscopic approach. The next step is to perform the first clinical case for example on a latissimus dorsi free muscle flap.

Pulmonary vein isolation with a novel endoscopic ablation system using laser energy.

Pulmonary vein isolation (PVI) is the basis of all ablation techniques for paroxysmal atrial fibrillation. Performing conventional radiofrequency ablation for PVI is time consuming and sometimes challenging when using point-by-point applications to create continuous lesions. Small electrically conducting gaps evolving in the ablation lines may cause recurrences of atrial fibrillation or regular atrial re-entry tachycardias. Development of novel anatomically designed ablation catheters for PVI aim to facilitate the ablation procedure, to produce continuous and durable lesions with a limited number of ablation impulses and to reduce the complication rate. The endoscopic laser balloon ablation system (HeartLight® EAS, Cardiofocus Inc.) is the first system that allows direct visual guidance of energy delivery at the antral level of each pulmonary vein and uses a completely new energy source for ablation.

Subfascial endoscopic perforator surgery (SEPS) in chronic venous insufficiency. A 14 years experience.

INTRODUCTION: Subfascial Endoscopic Perforator Surgery (SEPS) enables the direct visualization and section of perforating veins. Morbidity and duration of hospitalization are both less than with conventional open surgery (Linton's or Felder's techniques). PATIENTS AND METHODS: A total of 322 legs from 285 patients with a mean age of 56 years (range 23-90) were treated at our Department from May 1996 to January 2010. In 309 cases, an endoscope (ETM Endoskopische Technik GmbH, Berlin, Germany) was introduced through a transverse incision approximately 1.5 cm in length and 10 cm from the tibial tuberosity, as with Linton's technique. A spacemaker balloon dissector for SEPS, involving a second incision 6 cm from the first, was used in only 13 cases. RESULTS: The procedure used in each case was decided on the basis of preoperative evaluation. SEPS and stripping were performed in 238 limbs (73.91%), SEPS and short stripping in 7 limbs (2.17%), SEPS and crossectomy in 51 limbs (15.84%), and SEPS alone in 26 limbs (8.07%). 103 patients presented a total of 158 trophic ulcers; the healing time was between 1 and 3 months, with a healing rate of 82.91% after 1 month and 98.73% after 3 months. CONCLUSION: Subfascial ligature of perforating veins is superior to sclerotherapy and minimally invasive suprafascial treatment for the treatment of CVI. It is easy to execute, minimally invasive and has few complications.

[Angioscopy: a new intraoperative diagnostic and interventional tool for thoracic aortic treatment]. / Angioskopie: Neues intraoperatives diagnostisches und interventionelles Verfahren für die Therapie der thorakalen Aortenerkrankung.

In complex thoracic aortic disease endovascular techniques and the use of hybrid stent grafts enables a combination therapy of the aortic arch and the descending aorta through a median sternotomy. This emphasizes the importance of intraoperative visualization of the descending aorta and its pathologies. Intraoperative angioscopy is a new diagnostic method for the assessment of distal aortic disease and assists in therapeutic decision-making and navigation of endovascular techniques in the descending aorta. This study presents the angioscopic results of 62 patients (mean age 60±12 years, 73% male, 54 aortic dissections, eight aortic aneurysms) during surgery of the thoracic aorta. Visualization of the extent of pathology along the downstream aorta was feasible in all patients. The implantation of a hybrid stent graft prosthesis was assisted by angioscopy in 34 patients and endovascular balloon dilatation of the stent graft was navigated by angioscopy in 11 patients. Angioscopy has become an indispensable tool in the intraoperative treatment of complex thoracic aortic disease in our clinic, particularly in the navigation of endovascular interventions in the distal thoracic aorta through the aortic arch.

Towards real-time intravascular endoscopic magnetic resonance imaging.

Fast, minimally invasive, high-resolution intravascular imaging is essential for identifying vascular pathological features and for developing novel diagnostic tools and treatments. Intravascular magnetic resonance imaging (MRI) with active internal probes offers high sensitivity to pathological features without ionizing radiation or the limited luminal views of conventional X-rays, but has been unable to provide a high-speed, high-resolution, endoscopic view. Herein, real-time MRI endoscopy is introduced for performing MRI from a viewpoint intrinsically locked to a miniature active, internal transmitter-receiver in a clinical 3.0-T MRI scanner. Real-time MRI endoscopy at up to 2 frames/s depicts vascular wall morphological features, atherosclerosis, and calcification at 80 to 300 µm resolution during probe advancement through diseased human iliac artery specimens and atherosclerotic rabbit aortas in vivo. MRI endoscopy offers the potential for fast, minimally invasive, transluminal, high-resolution imaging of vascular disease on a common clinical platform suitable for evaluating and targeting atherosclerosis in both experimental and clinical settings.

Angioscopic detection of pulmonary thromboemboli: with special reference to comparison with angiography, intravascular ultrasonography, and computed tomography angiography.

INTRODUCTION: Pulmonary embolism (PE) is often fatal and its incidence is increasing worldwide. Detection of thromboemboli (TEi) is essential for a definitive diagnosis of PE. The detection of TEi using most imaging methods is low in patients clinically suspected of having PE. This study was carried out to detect TEi in the pulmonary arterial trees by angioscopy (AS); to classify TEi; and to compare the sensitivity of detection for TEi among AS, angiography (AG), intravascular ultrasonography (IVUS), and computed tomography angiography (CTA) in patients with clinically suspected PE. METHODS: After CTA, AG, and IVUS, the pulmonary arterial trees were surveyed by AS in 49 patients clinically suspected of having PE. RESULTS: TEi were found by AS, AG, IVUS, and CTA in 81.6%, 24.4%, 34.8%, and 22.5% of 49 patients, respectively. The 48 TEi classified by AS were globular (35%), mural (10%), cap-like (8%), web-like (4%), patchy (33%), and micro (18%). Cap-like, patchy, and micro-TEi were not detectable by AG, IVUS, and CTA in any subjects. TEi color was classified as red, white, yellow, and red-and-yellow in a mosaic pattern in 10%, 31%, 38%, and 18%, respectively. Red and white globular TEi were observed in acute, and red-and-yellow TEi in both acute and chronic PE patients. TEi other than globular were observed in both patient groups. CONCLUSION: Although invasive, AS is superior to AG, IVUS, and CTA for the detection of TEi, and therefore is a helpful imaging method for the definitive diagnosis of PE.

Cateter óptico para aplicaçöes espectroscópicas / Optic catheter for spectroscopic applications

Neste trabalho é apresentada a caracterização de cateteres utilizando fibras ópticas para aplicações de espectroscopia in vivo. Estes cateteres apresentam a configuração de seis fibras em torno de uma fibra central de mesmo diâmetro, sendo estas fibras do tipo multimodo com diâmetro de núcleo de 100 mum. A eficiência de coleta de radiação para este tipo de cateter é da ordem de 0,05 por cento, variando em função da distância ao tecido e da distribuição de intensidade de sinal retroespalhado na superfície do mesmo.

ln this work we describe the characterization of fiber optic catheters for in vivo spectroscopy applications. This type of catheters have the geometry of one central fiber sun-ounded by six 100 µm diameter multimode fibers. The collection efficiency of these type of catheter is about 0.05% and it changes with the distance to the tissue surface and the signal intensity distribution on it.