Interventional uroradiologic procedures can be divided into two major groups: vascular and percutaneous nonvascular. Percutaneous nonvascular interventional procedures are discussed elsewhere. The intravascular route is used, as the therapy of choice, for the embolization of arteriovenous fistulas (AVFs) or malformations, and for bleeding sites. Transcatheter embolization is used for tumor embolization, for the ablation of renal function, for the treatment of testicular vein and ovarian vein varices, and for the treatment of high-flow priapism (Ginat et al, 2009). Balloon angioplasty and stenting of stenotic renal arteries are frequently performed endovascular techniques for the treatment of ischemic nephropathy and secondary hypertension. Renal artery aneurysms may also be treated using catheter-directed techniques such as stent grafting and selective embolization. Occasionally, fibrinolytic agents are delivered via an endovascular catheter to thrombosed renal arteries. Mechanical devices are also available for endovascular treatment of thrombosed renal vessels. This chapter will review these intravascular interventions.
*The authors wish to thank Dr. Anthony Verstandig, Hadassah University Hospital, Jerusalem, Israel, for providing the clinical information and images of the patient depicted in Figures 7–4A and 7–4B.
Renal AVFs and Malformations
Transcatheter embolization is the treatment of choice for renal AVFs, which may be congenital, spontaneous, or acquired. Iatrogenic AVFs are the type most commonly treated by transcatheter embolization. These occur as a complication of such procedures as percutaneous renal biopsy (Libicher et al, 2006), nephrostomy placement, and pyelolithotomy. Trauma or surgery can also result in AVFs. AVF occurring in the transplant kidney is successfully managed by embolization. The classical angiographic finding of spontaneous or acquired AVF is a feeding artery with an early draining vein. Ancillary findings include pseudoaneurysm and extravasation of contrast material. Congenital AVMs (AV malformations) consist of a group of multiple coiled communicating vessels that may be associated with enlarged feeding arteries and draining veins.
The modes of clinical presentation include hematuria; retroperitoneal or intraperitoneal hemorrhage; and congestive heart failure, cardiomegaly, or both. Hypertension can occur as a consequence of ischemia secondary to venous shunting of blood away from the affected area. A bruit may be heard on physical examination. Duplex Doppler ultrasound is the most useful diagnostic study, performed before angiographic intervention.
Successful intervention requires the angiographic identification, selective catheterization, and embolization of the feeding artery (Figures 7–1A, B). Using a transfemoral approach, an abdominal aortogram is performed to identify the arterial supply to the bleeding kidney. In the case of a renal transplant, an initial pelvic angiogram is performed in a steep oblique projection. The artery supplying the bleeding site is selectively catheterized. A 3 French (3F) coaxial microcatheter is then used for subselective catheterization and embolization of the feeding artery. The use of a microcatheter allows accurate placement of the embolic material. Microcoils are used for the occlusion of iatrogenic AVFs because they can be deployed very precisely, thereby minimizing the loss of renal parenchyma ...