Alternative Renal Artery Reconstruction Techniques: Hepatorenal, Splenorenal, Iliorenal, and Mesorenal Bypass Procedures

Open renal revascularization for renovascular hypertension is being performed less often given advances in endovascular therapy. In fact, currently most renal artery bypass procedures are undertaken as part of hybrid operations accompanying endovascular interventions for aortic aneurysmal disease.

Alternatives to conventional renal revascularizations may be very important when an open procedure is needed. Marginal cardiac function or a hostile aorta because of coexistent aortic disease or prior aortic surgery can preclude safe aortic clamping for an endarterectomy or origination of a renal bypass accompanying an open procedure. In these cases, indirect reconstructions arising from the splenic, hepatic, superior mesenteric, or iliac arteries become a preferred intervention. When undertaking a splenorenal or hepatorenal bypass an appropriate imaging study must first document that the proximal celiac artery or its branches do not have an occlusive lesion significant enough to cause a pressure gradient that would perpetuate the hypertensive state following the reconstruction.

Certain general tenets apply to these alternative procedures. Exposure of the renal artery is similar in most alternative revascularizations. Preference is given to an extended subcostal or a transverse supraumbilical abdominal incision extending from the contralateral posterior axillary line to the ipsilateral posterior axillary line, in which the rectus muscles and oblique muscles are transected. Such a transverse abdominal incision provides a distinct technical advantage over midline incisions in the greater ease of handling instruments parallel to the longitudinal axis of the renal artery during complex procedures. The intestines are usually displaced outside the confines of the abdominal cavity.

Before the donor vessel or renal artery is occluded, the patient is systemically anticoagulated with intravenous heparin 150 mg/kg. Diuresis should be established with mannitol before interrupting renal blood flow. This is particularly important when performing hybrid procedures in patients who do not have antecedent renal artery occlusive disease. In contrast, patients with renovascular hypertension have preformed collateral vessels that usually provide sufficient blood flow to maintain kidney viability during the needed renal artery occlusion during its operative repair, and in these patients, cooling of the kidney or other adjunctive renoprotective measures are rarely needed.

Microvascular Heifetz clamps, developing noninjurious tensions of 30 to 70 g, are used in preference to conventional macrovascular clamps or elastic slings for occluding the renal vessels. Because they are very small, these microvascular clamps have the additional advantage of not obscuring the operative field. Once the renal anastomoses are completed and antegrade renal blood flow is established, the heparin anticoagulation is reversed with administration of intravenous protamine. The adequacy of the reconstruction is then assessed using duplex scanning or a directional Doppler. Specific comments about the individual procedures are warranted.

Splenorenal Bypass

Splenorenal bypass is the most commonly performed alternative renal artery reconstructive procedure for patients with left-sided disease. This usually involves a direct end-to-end anastomosis of the splenic artery to the renal artery ( Figure 1 ). Occasionally, this nonanatomic reconstruction requires an interposition vein graft between the splenic and renal arteries.

The left renal artery is exposed by medial reflection of the viscera, including the left colon, with identification and mobilization of the renal vein, which overlies the renal artery. This exposure is facilitated by ligation and transection of the gonadal and adrenal branches of the renal vein, which allows it to be elevated from underlying the renal artery. Such an extraperitoneal approach to the mid and distal renal vessels is preferred over exposure gained directly through an incision in the posterior retroperitoneum at the root of the mesocolon and mesentery. The renal artery should be mobilized for 2 to 3 cm beyond its aortic origin. This allows the freed artery to assume a gentle curve upward when anastomosed to the splenic artery, and it lessens the likelihood of kinking.

The preferred exposure of splenic artery is through the retroperitoneum after medial mobilization of the colon in a manner similar to that used for exposure of the renal artery. The fascial plane between the mesocolon, pancreas, and Gerota’s capsule over the anterior surface of the kidney is relatively avascular and allows easy elevation of the pancreas from the retroperitoneum. The splenic artery lies within a few centimeters above and in front of the left renal artery. It is easily palpated as it courses along the superior border of the pancreas.

Splenic arteries in women are often tortuous, and they are often heavily calcified in both genders. Because of the calcification, it may be difficult to mobilize the splenic artery for the anastomosis to the renal artery without its buckling or kinking, and care in its positioning before completing an anastomosis is very important. The problem of kinking is less likely to affect the proximal splenic artery, and dissection of this more central vessel is best started in its midportion, proceeding proximally. The splenic artery can be exposed directly through the base of the mesentery and mesocolon, but this approach is fraught with bleeding from small vessels and limits the length of splenic artery that can be dissected easily.

The splenic and renal arteries, or an interposition vein graft if needed, should be spatulated so as to create an ovoid end-to-end anastomosis. Although some report end-to-side splenic artery–to–renal artery reconstructions when significant size differences in these two arteries exist, this manner of anastomosis is not favored by most surgeons. Splenorenal bypasses in children are in disfavor because of early thromboses and later problems if celiac artery stenotic disease evolves, which would lead to recurrent hypertension.