|
 |
|||||||
Radiology
A 21-year-old lady presented with history of dyspnea ,weakness in both lower limbs since two years and was detected to be hypertensive since last two months. On clinical examination, her blood pressure was 210/150 mm of Hg ; both the lower limb pulses were feeble .Fundoscopic examination showed grade 1 hypertensive changes. She was on Depin and Atenelol.
Angiographic findings were consistent with aortoarteritis with affection of the left subclavian artery and aorta at the thoraco-abdominal junction in the form of high grade narrowing. The intraluminal aortic pressure gradient across the thoraco-abdominal aortic stenosis was 54 mm of Hg.
 |
| Fig 1 |
Stenting of the stenotic segment of thoraco-abdominal aorta was planned.
Through the right tranfemoral route using 10F sheath, prior to stenting, angioplasty of the stenotic segment was done using a 14 mm diameter balloon dilatation catheter (Medi-tech XXL, Boston scientific .Post angioplasty angiogram revealed a dissection, with significant residual stenosis in the stenotic segment (Fig.2).
 |
| Fig 2 |
A 40 -mm- long Palmaz balloon expandable stent (P5014 ,Cordis) was chosen for deployment across the stenosis The stent was mounted and crimped on a14 x 50mm diameter balloon catheter (Medi-tech XXL, Boston scientific ). However, after proper placement of the stent across the stenotic segment, during deployment and while inflating the balloon, the balloon slipped out of the stent and the distal end of the stent remained unexpanded with the proximal end flared (Fig .3).
 |
| Fig 3 |
Because of difficulty in negotiating even a small shaft diameter angioplasty catheter, through the undeployed stent which was placed across the stenosis, and possible difficulty in retrieving the stent due to the flared proximal end through the transfemoral route , it was decided to bring the stent as low as possible to enable it's deployment in the common iliac artery or aorta.
 |
| Fig 4 |
The retriever -18 endovascular snare (Target Therapeutics) was looped around the distal end of the stent (Fig 4) to bring it down till the aortic bifurcation beyond which retrieval was difficult (Fig.5)
 |
| Fig 5 |
Keeping the undeployed stent held, with the help of the snare in this position, a 14 x 50mm self expandable nitinol MEMOTHERM stent (ANGIOMED ,BARD) was introduced through10F right transfemoral sheath, parallel to it (Fig.6). This stent was then deployed across the stenosis satisfactorily and post-deployment angiogram showed no residual stenosis (Fig.7). Post-stenting, the intraluminal aortic pressure gradient across the stenosis was reduced to 8 mm of Hg.
 |
| Fig 6 |
 |
| Fig 7 |
After positioning the first partially deployed stent just proximal to the bifurcation, it was held in place by the snare and gradually dilated to the full aortic diameter after negotiating the balloon catheter.(Ultra -thin and Medi-tech XXL, Boston scientific ) through it. (Fig 8 and 9). Post stentplasty angiogram revealed appropriate placement of the stent in the infrarenal aorta (Fig.10) .
 |
| Fig 8 |
 |
| Fig 9 |
 |
| Fig 10 |
Discussion :
The use of endovascular stents to relieve hemodynamically significant vascular obstruction is common . During stenting ,apart from stent delivery procedure related complications like groin hematoma, dissection ,vessel perforation ,distal embolisation etc., the stent related complications like acute thrombosis, stent misplacement, dislodgment, pseudoaneurysm adjacent to the stented site , non-deployment can occur. A significant variety of techniques for retrieval of the undeployed dislodged stents have been described most of them are in relation with the intra-coronary balloon mounted stents .Large undeployed stents often necessitates arteriotomy after its retrieval upto iliac or common femoral artery because of its larger diameter.
Bogart et al described introduction of a parallel extra stiff support wire adjacent to the wire on which a lost stent remains to stabilize a snare for stent retrieval .This extra stiff guidewire provides greater degree of support or movement of not only the snare but also the sheath or other guiding catheters .With this technique there is potential for the stent to be bent or crushed at the proximal end as it may catch on the edge of the sheath with only distal snared end . If this occurs ,the stent cannot be withdrawn into the sheath .If it is a large-sized stent, it may not be retrievable even using 12 or 14 F sheaths. So a modification of this approach can be, to pass an additional wire through the struts of the proximal end of the dislodged stent and snare this second wire, thus creating a loop between the snare and end of the wire that has been used to traverse the struts of the stent.
Bioptomes of various sorts have been used to grasp dislodged stents .Retrieval of a migratory coronary stents by means of an alligator foreceps catheter, biopsy forceps have been described.
In some cases it is possible to pass a fixed wire balloon , through an unexpanded stents, inflate the balloon distally to the stent, and pull back the stent into the guide and further into sheath ("Fogarty" technique). It is also possible to place the contralateral sheath, snare and pull the wire, on which the stent is retained out through the contralateral sheath, and then from the ipsilateral side use a small calibre catheter over the guidewire to push the stent out of the contralateral sheath .
All these approaches are difficult, time consuming and sometimes harrowing . An alternative approach is to bury the stent particularly a small sized one, underneath the other stent after crushing the undeployed stent with a PTA balloon in a segment of the vessel that is not severely diseased .
This case illustrates a unusual potential problem when deploying Palmaz stent and offers a practical endovascular solution obviating the need for possible surgical intervention.