WORKUP	Section 5 of 11
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Lab Studies:

• A complete blood cell count, chemistry panel, coagulation profile, and urinalysis should be performed.

• In a patient with an RAA who does not have associated stenosis and severe hypertension, other endocrine sources should be excluded. These include the following:

• Pheochromocytoma - A 24-hour urine collection for vanillylmandelic acid, metanephrine, and normetanephrine

• Primary aldosteronism - Serum potassium

• Cushing syndrome - Cortisol levels

• Carcinoid - Urinary 5-hydroxyindoleacetic acid

Imaging Studies:

• Because most RAAs are asymptomatic and are found incidentally during a workup for other intra-abdominal pathology, imaging studies are required only for preintervention planning or longitudinal follow-up care.

• Duplex examination is the least invasive. The quality of imaging is highly operator-dependent and may be limited by the patient's body habitus.

• CT scan is the most widely available and reproducible imaging modality. It is the test of choice for diagnosis and follow-up. The advent of CT angiography and 3-dimensional reconstruction can allow for accurate preinterventional planning. Because intravenous iodinated dye must be used, its only real limitation is in patients who have a life-threatening dye allergy or impaired renal function. Non–life-threatening dye allergies can be managed with premedication with Benadryl (histamine-1 receptor antagonist), cimetidine (histamine-2 receptor antagonist), and Solu-Medrol.

• MRA with gadolinium enhancement and 3-dimensional reconstruction can produce images similar in quality to those with arteriography. This technology currently may not be as widely available as CT angiography.

• Arteriography is useful for helping define arterial anatomy prior to an intervention and, because of its invasiveness, should be used only for this purpose. It has largely been supplanted by CT angiography and MRA.

	TREATMENT	Section 6 of 11
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Surgical therapy:

Emergency surgical repair of ruptured renal artery aneurysm

Emergency surgery is required to control hemorrhage and prevent death from a ruptured aneurysm. A midline approach with supraceliac aortic control is required because exposure of the renal vessels may be difficult in the presence of a large perinephric hematoma. The aortic cross clamp can be removed once the renal artery is controlled. In most cases of rupture, renal salvage may not be possible because of hemodynamic instability; therefore, nephrectomy may be necessary. In a hemodynamically stable patient, renal salvage may be considered.

If the aneurysm extends to the kidney parenchyma, ex vivo repair followed by reimplantation may be necessary. In such circumstances, proceeding with nephrectomy may be safer as long as the patient has a functioning contralateral kidney.

Management of the gravid uterus in a pregnant patient with acute RAA rupture should follow the same principles observed when treating hemorrhage caused by intra-abdominal trauma in a pregnant patient. Cesarean delivery should be avoided if possible because it increases operative time and results in additional blood loss. Specific indications for cesarean delivery at the time of emergency laparotomy include interference of the gravid uterus with adequate exposure, fetal distress that outweighs the risk of fetal prematurity, and impending or recent maternal death.

Elective surgical repair of renal artery aneurysm

Elective repair of an RAA is generally undertaken to obviate the risk of rupture. A variety of operations are available for patients with RAAs who require surgical treatment. With improved surgical technique and earlier detection of these aneurysms, renal preservation should be considered the standard of care.

Tangential excision with primary repair or patch angioplasty

This is the procedure of choice for solitary saccular aneurysm at a proximal bifurcation and should be performed whenever feasible. It is associated with good anatomical and clinical results. Approximately one third of RAAs are amenable to such treatment. Aneurysms with small necks may be repaired primarily; otherwise, a patch angioplasty using autogenous saphenous vein or prosthetic material may be needed.

Aneurysm excision with reconstruction using bypass

This is indicated if simpler in situ arterioplasty is not possible, such as in large aneurysms or those associated with proximal renal artery stenosis. The preferred operation is aortorenal bypass using autogenous saphenous vein. This is typically constructed with an end-to-side configuration for the proximal anastomosis and an end-to-end configuration for the distal anastomosis. Prosthetic graft material is a suitable although less-preferable alternative, particularly in a younger patient. If the aorta is heavily diseased by atherosclerosis, alternative bypass donor arteries may be used. These procedures include splenorenal bypass, hepatorenal bypass, and iliac-to-renal bypass.

Extracorporeal vascular reconstruction with autotransplantation

This technique is useful for repair of complex hilar or intrarenal aneurysms involving multiple arterial segments, especially when more than 45 minutes of warm ischemia is anticipated. It is also useful for the treatment of renal artery dissection, particularly when multiple branches are involved or when acute thrombosis is present. Ex vivo surgery should be considered when in situ repair is deemed impossible or excessively difficult. Making this determination early is important, preferably before surgery, because considerable warm ischemia time may accumulate while in situ repair is being attempted, thus dooming the eventual ex vivo repair to failure. The advantages of this technique include a superficial blood-free operating field and the opportunity to use an operating microscope and microsurgical instruments.

Simple continuous perfusion of the kidney with cold heparinized saline solution may allow the kidney to be maintained safely ex vivo for 3 hours. This time may be extended if hypothermic pulsatile perfusion with Collins or University of Wisconsin solution is used. Once ex vivo reconstruction is complete, the kidney may be autotransplanted into the iliac fossa, as in renal transplant recipients, or replaced into the original renal fossa and attached to the renal vessels. The latter is favored because many ex vivo procedures are performed in relatively young patients. Attachment of the kidney to the iliac arterial system within or below sites commonly susceptible to significant atherosclerotic disease may adversely affect the long-term success of renovascular reconstruction.

Nephrectomy

Nephrectomy is indicated in patients with multiple large intrarenal aneurysms, severe ischemic renal atrophy, end-stage renal disease, renal infarction, associated renal lesions, or prior failed revascularization. Nephrectomy may be inevitable for patients with ruptured aneurysms.

Endovascular treatment of RAAs

Advances in endovascular techniques have led some investigators to attempt endovascular therapy for RAAs and other visceral aneurysms. This includes transcatheter embolization using various materials, including coils, or deployment of a stent-graft across the neck of an aneurysm to exclude it from the circulation. These techniques have limited use in the treatment of aneurysms with wide necks or those in close proximity to branch vessels. Although the clinical and angiographic success rates using these techniques are very high, the long-term results remain unclear. Periodic surveillance for patients treated with endovascular techniques is essential.

Preoperative details: Once the patient has been deemed a candidate for surgery, appropriate preparations are needed. As a minimum, all patients should have a complete blood cell count, chemistry panel, coagulation profile, urinalysis, and blood cross-match for 2 units. Patients older than 35 years should have an electrocardiogram and be appropriately screened and evaluated for cardiac disease prior to elective surgery. Patients older than 50 years or those with a history of pulmonary disease should have a preoperative chest radiograph.

Intraoperative details: Depending on the planned procedure, the patient should be positioned for either a transperitoneal or retroperitoneal approach. As with all aneurysm surgery, the principles of carefully obtaining proximal and distal control prior to dissecting around the aneurysm are essential. If a complex repair is anticipated, early consideration should be given to performing an ex vivo reconstruction.

Postoperative details: Standard principles of postoperative care should be applied.

Follow-up care: Ideally, patients should have a postoperative renal artery duplex scan. This can serve as a baseline for future studies. Abnormal findings on duplex images can be confirmed by performing CT scan, MRA, or arteriography. Those who have undergone endovascular repair merit close follow-up because long-term data on the success of this approach are lacking.