Katsunari Namba

Microcatheter Shaping for Intracranial Aneurysm Coiling Using the 3-Dimensional Printing Rapid Prototyping Technology: Preliminary Result in the First 10 Consecutive Cases.

OBJECTIVE An optimal microcatheter is necessary for successful coiling of an intracranial aneurysm. The optimal shape may be predetermined before the endovascular surgery via the use of a 3-dimensional (3D) printing rapid prototyping technology. We report a preliminary series of intracranial aneurysms treated with a microcatheter shape determined by the patients anatomy and configuration of the aneurysm, which was fabricated with a 3D printer aneurysm model. METHODS A solid aneurysm model was fabricated with a 3D printer based on the data acquired from the 3D rotational angiogram. A hollow aneurysm model with an identical vessel and aneurysm lumen to the actual anatomy was constructed with use of the solid model as a mold. With use of the solid model, a microcatheter shaping mandrel was formed to identically line the 3D curvature of the parent vessel and the long axis of the aneurysm. With use of the mandrel, a test microcatheter was shaped and validated for the accuracy with the hollow model. All the planning processes were undertaken at least 1 day before treatment. The preshaped mandrel was then applied in the endovascular procedure. Ten consecutive intracranial aneurysms were coiled with the pre-planned shape of the microcatheter and evaluated for the clinical and anatomical outcomes and microcatheter accuracy and stability. RESULTS All of pre-planned microcatheters matched the vessel and aneurysm anatomy. Seven required no microguidewire assistance in catheterizing the aneurysm whereas 3 required guiding of a microguidewire. All of the microcatheters accurately aligned the long axis of the aneurysm. The pre-planned microcatheter shapes demonstrated stability in all except in 1 large aneurysm case. CONCLUSION When a 3D printing rapid type prototyping technology is used, a patient-specific and optimal microcatheter shape may be determined preoperatively.

Use of Dyna-CT Angiography in Neuroendovascular Decision-Making: A Case Report

A successful neuroendovascular procedure depends on accurate anatomical understanding of a target vessel in relation to surrounding anatomical structures or endovascular devices, such as coils and stents. During an endovascular procedure, with conventional or three dimensional (3D) rotational angiography, this type of information is extremely difficult to obtain in a timely manner. To overcome this drawback, a DynaCT was combined with low dose contrast injection to create CT angiography (CTA)-like images (DynaCTA). The images obtained were similar to those of conventional CTA but with better quality in analyzing vessels to surrounding anatomical structures and endovascular devices while the patient was on the table. The authors present three illustrative cases in which information added by the DynaCTA helped improve understanding of anatomy, and affected our clinical decision-making. Although better quality images may be obtained by other imaging modalities or careful angiographic interpretations, DynaCTA can be an easy and effective rescue technique worth keeping in mind in clarifying the relation of a vessel to surrounding anatomy.

Manufacture of patient-specific vascular replicas for endovascular simulation using fast, low-cost method

Patient-specific vascular replicas are essential to the simulation of endovascular treatment or for vascular research. The inside of silicone replica is required to be smooth for manipulating interventional devices without resistance. In this report, we demonstrate the fabrication of patient-specific silicone vessels with a low-cost desktop 3D printer. We show that the surface of an acrylonitrile butadiene styrene (ABS) model printed by the 3D printer can be smoothed by a single dipping in ABS solvent in a time-dependent manner, where a short dip has less effect on the shape of the model. The vascular mold is coated with transparent silicone and then the ABS mold is dissolved after the silicone is cured. Interventional devices can pass through the inside of the smoothed silicone vessel with lower pushing force compared to the vessel without smoothing. The material cost and time required to fabricate the silicone vessel is about USD

Vascular Anatomy of the Cauda Equina and Its Implication on the Vascular Lesions in the Caudal Spinal Structure

2 and 24 h, which is much lower than the current fabrication methods. This fast and low-cost method offers the possibility of testing strategies before attempting particularly difficult cases, while improving the training of endovascular therapy, enabling the trialing of new devices, and broadening the scope of vascular research.

Swine hybrid aneurysm model for endovascular surgery training.

The cauda equina is composed of the lumbosacral and the coccygeal nerve roots and the filum terminale. In the embryonic period, discrepancy in development between the termination of the spinal cord and the spinal column results in elongation of the nerve roots as well as the filum terminale in this region. Although the vascular anatomy of the caudal spinal structure shares many common features with the other metameric levels, this elongation forms the basis of the characteristic vascular anatomy in this region. With the evolution of the high quality imaging techniques, vascular lesions in the cauda equina are being diagnosed more frequently than ever before. Albeit the demand for accurate knowledge of the vascular anatomy in this region, descriptions are often fragmented and not easily accessible. In this review, the author attempted to organize the existing knowledge of the vascular anatomy in the cauda equina and its implication on the vascular lesions in this region. Also reviewed is the clinically relevant embryological development of the cauda equina.

A new hemostasis valve for neuroendovascular procedures.

The aim of this study was to develop a technically simple swine aneurysm-training model by inserting a silicone aneurysm circuit in the cervical vessels. A silicone aneurysm circuit was created by designing multiple aneurysms in size and configuration on a silicone vessel. Five swine underwent surgical implantation of this circuit in the cervical vessels: one end in the common carotid artery and the other in the external jugular vein. Using this model, an aneurysm coiling procedure was simulated under fluoroscopic guidance, roadmapping and digital subtraction angiography. Creating an aneurysm model for training purposes by this method was technically simple and enabled the formation of a wide variety of aneurysms in a single procedure. The quality of the model was uniform and the model was reproducible. Coiling training using this model resembled a realistic clinical situation. The swine hybrid aneurysm-training model was advantageous from the standpoint of technical simplicity in the creation and variety of aneurysms it provided. The swine hybrid aneurysm model may be an additional option for aneurysm coiling training.

A patient-specific intracranial aneurysm model with endothelial lining: a novel in vitro approach to bridge the gap between biology and flow dynamics

A hemostasis valve is routinely used in neuroendovascular procedures to decrease the risk of thromboembolism 1,2. Recently, a new hemostasis valve that is designed to minimize blood loss has been introduced. We report our initial experience in using this new hemostasis valve. In neuroendovascular procedures, a hemostasis valve is commonly used for continuous irrigation of guide and microcatheters to decrease the risk of thromboembolism 1,2,3. A conventional hemostasis valve has a rotating seal at the end, which is turned open or closed each time a wire or microcatheter/guidewire is introduced or extracted. Often this results in significant back bleeding. When a rotating seal is adjusted suboptimally during a wire or microcatheter manipulation, leakage of pressurized saline from the end of a hemostasis valve results in stagnation of blood within a guiding catheter, which becomes a potential source of emboli during a procedure. The Guardian Haemostasis Valve (Zerusa Limited, Galway, Ireland) is a new hemostasis valve that is designed to minimize blood loss during interventional procedures by minimizing the opening time of the valve during wire or microcatheter insertion. A continuous sealing mechanism during wire or microcatheter positioning minimizes blood loss and stagnation of blood within the guide catheter. We report our initial experience with the Guardian hemostasis valve.

Ocular thrombosis after stent-assisted coiling of a c7 (paraclinoid) internal carotid artery aneurysm. A report of two cases and literature review.

Objectives To develop an in vitro model for studying the biological effect of complex-flow stress on endothelial cells in three-dimensional (3D) patient-specific vascular geometry. Materials and methods A vessel replica was fabricated with polydimethylsiloxanes using 3D printing technology from vascular image data acquired by rotational angiography. The vascular model was coated with fibronectin and immersed in a tube filled with a cell suspension of endothelium, and then cultured while being slowly rotated in three dimensions. Culture medium with viscosity was perfused in the circulation with the endothelialized vascular model. A computational fluid dynamics (CFD) study was conducted using perfusion conditions used in the flow experiment. The morphology of endothelial cells was observed under a confocal microscope. Results The CFD study showed low wall shear stress and circulating flow in the apex of the basilar tip aneurysm, with linear flow in the parent artery. Confocal imaging demonstrated that the inner surface of the vascular model was evenly covered with monolayer endothelial cells. After 24 h of flow circulation, endothelial cells in the parent artery exhibited a spindle shape and aligned with the flow direction. In contrast, endothelial cells in the aneurysmal apex were irregular in shape and size. Conclusions A geometrically realistic intracranial aneurysm model with live endothelial lining was successfully developed. This in vitro model enables a new research approach combining study of the biological impact of complex flow on endothelial cells with CFD analysis and patient information, including the presence of aneurysmal growth or rupture.

Wire-probing technique to revascularize subacute or chronic internal carotid artery occlusion.

Stent-assisted coiling of paraclinoid aneurysms is widely performed in neurointerventional surgery. The most common adverse event related to this procedure is cerebral thromboembolism. However, reports on ocular thromboembolism are scarce. We report our experience with two patients who developed ocular thromboembolism following Enterprise stent-assisted coiling of paraclinoid aneurysms. We then review the available literature for the possible pathomechanism of ocular thrombosis. Ocular thromboembolism may be a risk of stent-assisted coiling when the stent traverses the orifice of the ophthalmic artery or the stent is placed in the C3 internal carotid artery. Further study is needed to clarify how to avoid this disabling complication.

A case of Marfan syndrome with ischemic stroke due to middle cerebral artery dissection

During endovascular revascularization of subacute and chronic occlusion of the cervical internal carotid artery (ICA) it may be difficult to penetrate the lesion. Selecting the appropriate “true lumen”, a remnant of what had been the arterial lumen, at the initial step may facilitate the procedure. Because plaque at the carotid bifurcation is known to propagate from the posterior wall, a gateway to this “true lumen” should exist in the anterior side of the occluded stump. This hypothesis was studied retrospectively in our series of revascularizing ICA subacute and chronic occlusion. Eleven patients underwent endovascular revascularization for symptomatic cervical ICA occlusion. Procedures were performed by initially penetrating the occluded stump with a guidewire, followed by supporting catheter advancement through the occluded segment to secure the distal normal arterial lumen. Cases were analyzed with regard to the location of initial guidewire penetration. Eight patients underwent successful revascularization. In five cases, the entry point to the occluded stump was located at the anterior side, and in three, at the posterior side. Two posterior stump penetration cases were met with resistance in guidewire advancement, whereas penetration was smooth in the anterior cases. In addition, two posterior stump penetration cases resulted in contrast stasis in the posterior ICA wall. In our series of revascularizing cervical ICA subacute and chronic occlusion, initially targeting the anterior side of the occluded stump resulted in favorable results. This may be the result of selecting the “true lumen” at the beginning of the procedure.