ABSTRACT
Technique of recanalization Iliofemoral veins and IVC Owing to the lack of signs or symptoms of an occluded iliofemoral venous system in CHD patients undergoing cardiac catheterization, the operator must have a high index of suspicion and be prepared to handle an occlusion, especially if the patient has a history of multiple vascular access as an infant. When excellent blood return from a needle is not met with successful passage of a guide wire into the femoral vein, one should make a small hand injection into the needle to evaluate the vessel rather than simply remove the needle to start again. If the femoral vein is occluded, contrast will enter into venous collaterals that commonly circulate into the paravertebral venous system and eventually exit into a more proximal patent iliac system or IVC or contralateral iliofemoral venous system. An angiogram should be performed in both anteroposterior (AP) and lateral projections to evaluate these vessels. Special attention should be paid at the beginning of the injection to look for the “beak” of the remnant supercial femoral vein (Figure 16.1) before superimposition by contrast in the venous collaterals. Even when the angiogram is taken at 30-60 frames per second, only 1-2 frames may show this “beak.” Sometimes the “beak” is obvious, and at other times it can be very subtle, as shown in two patients in Figures 16.2 and 16.3. e lateral projection is particularly helpful because of the anterior course of the supercial femoral vein remnant in contrast to the venous collateral ow, which takes a more posterior course
AP APlat lat
into the paravertebral venous system. When this “beak” is identied, there is high likelihood for a successful recanalization. First, a small (0.014-0.018") guide wire is passed into the tip of the “beak” under uoroscopic guidance. e needle is replaced with a cannula to secure the initial access. Occasionally, an angled guide wire is all that is needed to push past the “beak” and up the occluded vessel. More commonly, the wire will simply buckle. e cannula should be exchanged for a 4-5 Fr dilator, which prevents the wire from buckling during its advancement. With support from the dilator, which is pushed up to the tip of the “beak,” the angle guide wire is advanced. If the front end of the wire is too so, then the stier back end of the wire can be used. e wire is advanced in small increments (mm), followed by advancement of the dilator. e wire is removed and repeated small hand injections are made to evaluate the course (Figure 16.4a and b). Contrast may stain the lumen of the thrombosed vessel. is sequence is repeated until contrast is seen owing freely in the proximal patent vessel, which could be the iliac vein if the occluded segment is short or even as far as the IVC if there is a long segment occlusion (Figure 16.4c and d). It is important to note the anterior course of this vessel and to assess for extravasation (Figure 16.5a-c). Once the wire is passed into the patent segment, the occluded segment can be serially dilated with either progressively larger dilators or dilation balloons until it is large enough to accommodate a sheath. It is advisable to use a long sheath (such as a Mullins sheath) to secure a long-segment occlusion for the cardiac catheterization. e planned procedure should be performed rst and the vessel should be stented
at the end of the planned procedure. An angiogram of the entire length of the iliofemoral venous system and IVC should be performed in order to assess the diameters for proper stent and balloon size selection. When a single stent is inadequate to cover the entire length of the occluded segment, multiple overlapping stents should be used starting from the most cranial end (Figure 16.6a and b). When the occlusion involves the IVC, patency is oen seen at the level of the renal veins, most likely due to the high ow of these veins back into the IVC. Presently, only balloon-expandable stents are used in growing children to accommodate future further dilation as the child grows. e Genesis stent is a good choice for these vessels. Balloon size selection should be based on the normal caliber of the adjacent patent vessel. During stent implantation, a clamp is placed on the inguinal ligament to dene the caudal limit for stent positioning. A needle is usually placed on the groin, parallel to the femoral vein course, to help determine the level at which the tip of the needle can enter the stent. By positioning the stent such that the most caudal edge can be entered by the percutaneous needle, future access into the stent is ensured even if the stent becomes reoccluded. However, keep in mind that on the lateral projection, the stent should not be positioned too anteriorly so that exion of the hips will distort the stent. In general, if the stent is positioned such that its most caudal edge is in the mid-portion of the bladder, it is safe from hip exion. At the end of the procedure, the hips can be exed under lateral uoroscopy to ensure stent positioning. Follow-up angiogram should be taken to evaluate inow (Figure 16.7a-c). If the distal femoral vein is small or
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the inow into the stent appears inadequate, there is a possibility of stent reocclusion. is should not pose a hemodynamic problem since the vein was occluded in the rst place prior to recanalization. However, by having the stent in place, future catheterizations can still be performed even if the stent occludes. By using biplane uoroscopic guidance, a needle can be directed into the lumen of the radiopaque
stent and advanced further into the patent vessel distally. As long as the needle remains inside the stent, extravasation is avoided. As shown in the Figures 16.8 and 16.9, multiple catheterizations were performed for cardiac biopsies in a transplant patient in whom an occluded femoral vein was stented and became reoccluded due to poor inow. As the child grew, longer (Chiba) needles were needed to reach
the stent edge, but once there, a wire was easily advanced through the thrombosed stent and nally into the more cranial patent segment of the femoral vein. Following stent implantation in a systemic vein, lifetime antiplatelet therapy with low-dose aspirin is prescribed. Occasionally, the occluded venous segments can be quite extensive, requiring multiple stents involving bilateral femoral and iliac veins as well as the IVC as shown in Figures 16.10 through 16.13.
