Microcatheter coaxial

Technically, solid - i.e., polyvinyl alcohol particles (PVA), platinum coils - and liquid embolics are used that are delivered through microcatheters coaxially introduced into a distal superselective position... 

The more peripheral the embolization is to the tumor, the less the opportunity for collateral circulation and the greater likelihood of tumor necrosis. While tumor necrosis is a desired effect, necrosis of adjacent non-targeted tissue is not. Microcatheter coaxial systems allow subselective or superselective embolizations to access tumor vessels and avoid non-targeted embolization. Peripheral embolization produces small vessel occlusion without sacrificing the main arteries, allowing future re-embolization when necessary. 

Technical Considerations Catheterization of the bronchial arteries is best approached from the femoral artery. Since most patients with lung cancer are older and the aorta is tortuous and atherosclerotic, a 5-F catheter with good torque control in a shepherd s crook (reverse curve) or forward seeking configuration is recommended. A finely tapered tip catheter for access which would allow a 3-F microcatheter coaxial system is optimal to bypass the spinal artery. The use of nonionic contrast media should minimize pain and the risk of contrast media-induced complications. The digital subtraction technique is of value for the identification of the anterior spinal artery with small branches to the spinal cord. 

Local intra-arterial thrombolysis (lAT) has several theoretical advantages over IV thrombolysis. For instance, by using coaxial microcatheter techniques, the occluded intracranial vessel is directly accessible and the fibrinolytic agent can be infused directly into the thrombus. This permits a smaller dose of fibrinolytic agent to reach a higher local concentration than that reached by systemic infusion, and ideally it allows for more complete recanalization with lower total doses of thrombolytic. With the smaller dose, complications from systemic fibrinolytic effects, including ICH, can theoretically be reduced. 

Controlled delivery of all pushable fibered Micro coils (Cook, Boston Scientific and Cordis) 0.018 in. is possible by using a coaxial guide (4-6 F) and microcatheters [14]. In order to achieve cross sectional occlusion of the artery or vein, the micro coils must be delivered into a tight coil mass. To achieve this, a 0.016 pusher wire (Boston Scientific or Cordis) is used and the same weaving action is performed during deployment in order to nest/pack the microcoil into a tight coil mass (Fig. 3.3). 

Fig. 3.9a-d. A standard 7-F gonadal guide catheter for occlusion of the left spermatic or ovarian vein (Cordis Inc., Miami, FL) is demonstrated in (a) and in (b) the 7/5 pulmonary guiding catheter and inner catheter for occlusion of pulmonary arteriovenous malformations is shown. Once the ovarian or internal spermatic vein are catheterized, any standard 100-cm 5-F endhole multipurpose catheter is advanced over a Bentson wire deep into the spermatic or ovarian vein where sclerosants and coils are usually placed. A standard 6-F RDC (Cordis Inc., Miami, FL) guide catheter for visceral embolization is demonstrated with a coaxial 4-F catheter in (c) and in (d), a triaxial system is demonstrated with an inner 0.021 lumen microcatheter... 

Properties of the microcatheters and micro-guidewires we use are listed in Table 5.4. Most companies offer adequate coaxial systems. We do not adhere to specific brands and have used all kinds of microcatheters and microguidewires over the years. 

Takahashi K, Yamada T et al. (2001) Selective balloon-occluded retrograde sclerosis of gastric varices using a coaxial microcatheter system. AJR Am J Roentgenol 177 1091-1093... 

For this reason, when an embolotherapy is planned we recommend immediate cessation of prostaglandin Ej agonist infusion. In case of arterial spasm at the ostium of the uterine artery, the use of a coaxial system with a microcatheter is then required. It is possible to successfully catheterize the distal part of the uterine artery in most cases. In these circumstances, the preferred embolic agent is the one that can be easily delivered through a microcatheter, such as PVA (Polyvinyl alcohol) or Embospheres. We prefer to use particles with larger diameters, such as Embospheres 700-900 mg. Even if these particles are used for the above-mentioned reasons, additional Gelfoam embolization of internal iliac arteries is performed because of the extensive collateral pathways of the female pelvis. 

The most commonly used liquid tissue adhesives are cyanoacrylates. Their low viscosity makes their delivery easy through small coaxial microcatheters. However, their rapid polymerization when in contact with blood, can make precise and safe occlusion challenging. Usually they are mixed with an oil-based contrast media, such as Ethiodol (Savage Laboratories, Melville, NY). The contrast serves to both opacify the cyanoacrylate and slows the polymerization time [30]. 

Tanaka N, Yamakado K, Murashima S, Takeda K, Matsu-mura K.NakagawaT et al. (1997) Superselective bronchial artery embolization for hemoptysis with a coaxial microcatheter system. J Vase Interv Radiol 8(1 Pt l) 65-70... 

The use of a coaxial microcatheter for catheterization and embolization may be needed to increase stability or to embolize the venous sac [9, 79]. In addition, the use of a microcatheter avoids... 

Following the initial anatomic survey, superselective right or left hepatic artery catheterization is then performed. While this is often possible with standard 4- to 5-F diagnostic angiographic catheters, coaxial microcatheter systems for all chemoembolization procedure are preferred. Microcatheter systems are easier to negotiate through tortuous hepatic arterial anatomy and probably reduce catheter-related spasm, thrombosis, and dissection. When tumor occupies more than 50% of the liver, or when the portal vein is occluded, microcatheter systems facilitate further... 

The celiac trunk and hepatic artery are usually catheterized by 4-F or 5-F catheters (cobra or sidewinder configuration), while the tumor-bearing target vessels should be approached by 2.7- to 3-F coaxial micro-catheters. The advantages of a microcatheter system are the increased injection resistance, which reduces the risk of microsphere reflux, and the smaller likelihood of vascular spasms. 

Coaxial use of a microcatheter or direct embolization through Cobra... 

Typically a groin approach is used and the celiac axis is selected with a Sos catheter. Selective angiography is performed to lay out the splenic artery. A glidewire is then passed distally and either the Sos or a Cobra catheter is advanced. Embolization can be performed through the 5 French catheter at this point. If too tortuous, then a microcatheter can be passed coaxially. (Fig. 8.4) We use either a Mass Transit (Cordis, Miami, FL) or Renegade (Boston Scientific, Boston, MA) microcatheter. These catheters can withstand a power injection of 2-3 cc per second if needed. 

Fig. 8.4. a Nonselective celiac angiogram in a patient with a large splenic pseudoaneurysm after trauma. Note the marked vasospasm and contrast pooling in the left upper quadrant, b Coaxial use of a microcatheter to obtain access distal to the neck of the pseudoaneurysm despite the vasospasm, c Follow-up splenic angiogram after coil embolization of the splenic artery. No further contrast extravasation was noted and the patient s vitals stabilized. (Courtesy of James R. Duncan, MD)... 

The RIM catheter was specifically designed for the inferior mesenteric artery. This catheter typically seats well in the origin, which arises at the level of the left pedicle of L3. A microcatheter can then be passed coaxially into the desired branch and microcoils deposited. Superselective technique is desired. Although some collateral flow is supplied to the distal colon via internal iliac branches, care must be taken when occluding more proximal vascular territories. 

Selecting the final catheter position Simmon s 1 or Cobra (Terumo) glide catheter over 0.035 glide wire (Terumo) 3 Fr microcatheter (Renegade, Boston Scientific ) coaxially through the 5 Fr or 4 Fr catheter over a 0.018 -wire (Transend, Boston Scientific)... 

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