"Accordion" deformity of a tortuous external iliac artery after stent-graft placement.

PURPOSE: To identify a complication of endograft deployment in aneurysmal iliac arteries. CASE REPORT: A 71-year-old man was referred for endovascular treatment of a 60-mm-diameter right common iliac artery aneurysm; however, deployment of a homemade covered stent (Palmaz-Schatz and polytetrafluoroethylene) induced shortening of the tortuous external iliac artery, causing an "accordion" deformity. The anomaly proved difficult to treat with serial Wallstent deployment, because the convolution tightened and migrated caudally with each stent deployed, threatening outflow. Finally, after 3 Wallstents were implanted, the contour of the external iliac artery was straight, and flow was unimpeded. However, 3 weeks later, the external iliac artery had recoiled to its original redundant appearance, but flow remained satisfactory. The aneurysm remains excluded, with satisfactory distal flow after 24 months. CONCLUSIONS: Implanting endografts in redundant, tortuous arterial segments may prove problematic, since induced straightening by the device precipitates kinking in the redundant system. Although treatment may be required in some situations, the vessels may return to a noncompressed state by removing the delivery system and guidewire.

Carbon dioxide/digital subtraction arteriography-assisted transluminal angioplasty.

During a 62-month period, carbon dioxide was used to supplement or completely replace iodinated contrast agents in performing 27 transluminal angioplasties in 26 patients. The arterial segments addressed included the following: renal in two cases, iliac in five, femoral/popliteal in 15, infrapopliteal in two, and combined in three. Indications for intervention included lower extremity gangrene in 11 cases, ischemic ulceration in 10, rest pain in three, claudication in one, and ischemic nephropathy in two. Contraindications to iodinated contrast agents included renal insufficiency resulting from diabetes (n = 20) or ischemic nephropathy (n = 2) and congestive heart failure (n = 4). Eight procedures used carbon dioxide as the sole contrast agent, whereas 19 required supplementation of carbon dioxide with a mean of 39 ml of nonionic contrast medium. Technical success was achieved in 25 procedures with significant hemodynamic improvement in 20 patients. Complications included transient deterioration in renal function in two patients and myocardial infarctions in two. At 30 days 18 patients had demonstrated significant clinical improvement. Patients at high risk for iodinated contrast-related complications may undergo transluminal angioplasty using carbon dioxide/digital subtraction arteriography to reduce or eliminate the need for iodinated contrast agents.

Upregulation of angiotensin II type 1 receptor gene expression in chronic renovascular hypertension.

Although the renin-angiotensin system has been implicated in the pathogenesis of renovascular hypertension (RVH), blood pressure does not parallel serum levels of renin or angiotensin II (AII) in chronic RVH. Upregulation of angiotensin II type 1 receptor (AT1) gene expression may explain this paradox and clarify the pathogenesis of chronic hypertension in RVH. To investigate this hypothesis, we studied changes in AT1 mRNA levels in rat kidney in a two-kidney, one-clip (2K1C) rat model of RVH. Animals were sacrificed at 1 or 10 weeks postoperatively. Blood pressure was measured with a tail cuff photosensor. Relative gene expression was quantitated by dot blotting total RNA, hybridizing with a cDNA probe for AT1, and quantitating signal intensity with scanning densitometry. A significant increase in blood pressure (BP) was observed at 1 week postoperatively (delta BP: 2K1C = +24 mm Hg, n = 3; controls = +7 mm Hg, n = 3; P < 0.05), and at this time relative AT1 mRNA levels actually decreased in the clipped kidney (P < 0.05). Hypertension intensified 10 weeks postoperatively (delta BP: 2K1C = +46 mm Hg, n = 20; controls = -17 mm Hg, n = 7; P < 0.005) and, remarkably, was paralleled by an almost sevenfold upregulation of AT1 mRNA levels in the clipped kidney (P < 0.005) and more than eightfold in the unclipped kidney (P < 0.005) of 2K1C animals. Upregulation of renal AT1 gene expression could lead to increased AT1 receptor production, hypersensitivity to AII, and chronic hypertension in RVH.