Anatomical variants of the renal arteries are relatively common [1], and multiple renal arteries with two hilar arteries are the most common anatomical variation. Accessory renal inferior polar arteries are also common type of multiple renal arteries [2]. If an abdominal aortic aneurysm (AAA) coexists with an ectopic main renal artery originating from the aneurysmal sac, a proper surgical strategy must be followed to preserve the renal function of the kidney perfused by the ectopic artery. Herein, we present a rare case of an AAA with an ectopic right main renal artery originating from the aneurysmal sac, perfusing a normotopic right kidney. The patient’s consent was received for the publication of this paper.

A 68-year-old male was referred to our department with vague abdominal pain and a pulsatile abdominal mass. His medical history included arterial hypertension, hyperlipidemia, coronary artery disease with myocardial infarction treated by stenting, and an ejection fraction (EF) of 40%.

The patient had no family history of AAA. Computed tomography (CT) with an angiographic protocol revealed an infrarenal AAA with a maximum diameter of 5.5 cm, with an ectopic right main renal artery originating from the aneurysmal sac located anterior to the inferior vena cava (Fig. 1, 2). A right common iliac artery aneurysm with a 2.1 cm diameter was also noted, but no other accessory renal arteries were detected. We decided to treat the patient with an open surgery because of the ectopic right-sided renal artery from the aneurysm sac. A midline incision was made under general anesthesia. After preparing the infrarenal aorta, common iliac arteries, and right renal arteries, 5,000 IU of unfractionated heparin was administered intravenously. Two liters of cold (at 4°C) lactated Ringer solution enriched with mannitol (12.5 g/L), methylprednisolone (125 mg/L), and heparin (2,000 U/L) had already been prepared, and 1 L of the solution was connected to a peristaltic pump; bags with ice cubes were also prepared to protect the right kidney in situ and its renal function. No other solution, such as solutions widely used in organ transplantation, was used because the potassium and adenosine content could cause cardiovascular complications.

Figure 1. Multiple axial images of the outgrowth of the right ectopic renal artery from the sac of the infrarenal aortic aneurysm and its anterior location to the inferior vena cava on contrast-enhanced computed tomography.

Figure 2. Preoperative three-dimensional contrast-enhanced computed tomography: left renal artery (black arrow) and right renal artery (black dotted arrow) with ectopic location from the infrarenal abdominal aneurysm (white arrows); small aneurysm of the right common iliac artery (white dotted arrow).

The aorta was cross-clamped inferior to the left renal artery and distally just above the bifurcation. An aortic Carrel patch was created with the orifice of the right renal artery, and the right renal artery was catheterized and perfused with cold enriched Ringer solution at a rate of 70 mL/min [3]. A tube polyester 16-mm Dacron graft was anastomosed to the infrarenal aorta (inferior to the left renal artery, polypropylene 3.0). Upon completing the proximal anastomosis, the aortic Carrel patch with the right renal artery orifice was anastomosed to the mediolateral right side of the tube graft (polypropylene 4.0), where an opening was already created. Immediately, the clamp was moved beyond this anastomosis; the total hypothermic ischemia of the right kidney was <16 minutes (Fig. 3, 4).

Figure 3. Intraoperative photograph of the ectopic right main renal artery from the sac of the infrarenal aortic aneurysm.

Figure 4. A tube polyester 16 mm Dacron graft was anastomosed to the infrarenal aorta, and the aortic Carrel patch with the right renal artery orifice was anastomosed to the mediolateral right side of the tube graft.

Consequently, the distal end of the tube graft was anastomosed to the aortic bifurcation, and perfusion of the lower torso was restored. Finally, the fully exposed right common iliac artery was 360° wrapped with a polyester band covering the entire length of the vessel; the band was fixed with running sutures throughout the same length. The patient was extubated in the operating room, recovered rapidly, and was discharged from the hospital in good condition on the 9th postoperative day, with normal postoperative levels of urea (urea=35 mg/dL) and serum creatinine (Cr=1.1 mg/dL). Five years later, follow-up with contrast-enhanced CT revealed patency of the right renal artery and a normally enhanced right kidney (Fig. 5); all laboratory values were normal.

Figure 5. A follow-up with three-dimensional contrast-enhanced computed tomography revealed patency of the right renal artery (black dotted arrow), reconstruction of the infrarenal abdominal aorta (white arrows), small aneurysm of the right common artery (white dotted arrow), and left renal artery (black arrow).

Anomalies of the renal vasculature are common and, as a rule, are asymptomatic. Their discovery is often incidental, usually following an abdominal CT scan for other reasons. However, in the case of the coexistence of an AAA that has to be repaired, anomalies of the renal vasculature, such as an ectopia of the main renal artery, or when important accessory renal arteries are present and should be preserved, a personalized surgical strategy is mandated to avoid hemorrhage or preserve renal perfusion [4-6]. In the present case, the patient had an AAA with an approximately 4% annual rupture risk [7], and although he had two normotopic, normally functioning kidneys, he had an ectopic main right renal artery originating from the aneurysm sac, which is an infrequent finding. As in most reported cases of renal artery ectopia, the ectopic arteries had a high origin above their usual anatomic position or concurred with an ectopic kidney [8,9]. Doppman [10] first described a single ectopic renal artery without renal malformation or mispositioning in 1967.

In the case of a concurrent aortoiliac aneurysm, although the existence of multiple arteries (frequency 15%-30%) or important accessory arteries (23%) [6] already demands careful planning for their salvage, the surgical tactic is also challenging in the case of an ectopic main renal artery that arises from the aneurysm sac, similar to a concomitant AAA with a pelvic kidney (usually with a low renal artery origin) or when there is an aortoiliac aneurysm in a patient with a kidney transplant [11]. Although polar renal arteries are usually small-caliber and can be sacrificed with little loss of renal parenchyma, some authors advocate a polar artery with a diameter of >2 mm requires salvage [12]. The Society of Vascular Surgery guideline recommends the preservation and reimplantation of a major accessory renal artery with a diameter >3 mm or those that supply one-third or more of the kidney during open aneurysmal repair [13].

When ectopia of the main renal artery is involved in AAA repair, preserving the artery and protecting the relevant kidney are the two cornerstones of treatment. Preoperative hydration and the intraoperative systemic administration of mannitol, dopamine, and furosemide along with the stabilization of arterial blood pressure, are usually supportive of normal renal function in aortic surgery [14]. However, during AAA repair, aortic cross-clamping interrupts kidney perfusion when the main feeder arises from below the cross-clamping, as in our case. Most investigators suggest measures for preserving the renal function of the kidney at risk when extended renal ischemia is anticipated, as in thoracoabdominal aneurysm repair. Left heart bypass or tubes (Gott shunt) can be used as adjuncts to perfuse the renal arteries during aortic reconstruction until the final reimplantation of the renal arteries. However, these manipulations could lead to hemorrhage or renal artery injury [15].

In simpler cases, during juxtarenal AAA repair with suprarenal or interrenal aortic cross-clamping, cold renal perfusion is not always necessary because the expected renal ischemic time is not long. In a review of Vascular Quality Initiative data from the United States, cold renal perfusion was used in 10.4% of inter-renal clamping and 14.3% of suprarenal clamping cases; notably, ischemia for more than 40 minutes has been associated with poor outcomes such as acute kidney injury, new-onset renal replacement therapy, and 1-year mortality [16]. Regarding renal ischemia time, our case presented a unique situation. In our case, renal perfusion could be restored after proximal aortic graft anastomosis and additional renal artery reimplantation different from standard AAA repair. Therefore, we performed cold renal perfusion because the renal ischemic time was suspected to be longer than that of traditional surgery for normotopic renal arteries. Although there is no unique and safe regime, most authors suggest perfusing the kidney with cold (4°C) lactated Ringer solution with heparin, mannitol, or methylprednisolone [15]. Regarding methods for cold renal perfusion, it is possible to use selective infusions of a bolus of solution, repeated every 10-30 minutes or continuously infused. No direct comparison exists regarding perfusion methods between intermittent and continuous infusions in AAA; therefore, both methods could be used. However, regardless of the technique used, cold crystalloids should only be delivered unless the patient is not too cold or is volume-overloaded.

Proximal aortic-to-graft anastomosis and reimplantation of the ectopic right renal artery via the Carrel patch were performed in less than 16 minutes in our case, as the patient was thin and the artery was in a suitable position for reconstruction. However, some cases require much more time, especially in cases of complications such as hemorrhage; in this situation, renal protection is possible using selective infusions of a bolus of cold (4°C) Ringer lactate, repeated every 20 minutes or continuously infused [17]. Renal artery reconstruction per se depends on artery quality and caliber. Using an aortic collar (Carrel patch) is the most widespread tactic, although jump grafts can be used without any perfusion adjunct.

Finally, in this case, we decided to act promptly as the patient’s general condition was borderline due to low cardiac EF; thus, the distal anastomosis of the tube graft was performed at the aortic bifurcation, and the aneurysm of the right common iliac artery was simply 360° wrapped by a band of the remaining polyester graft. Although the iliac aneurysm was small (diameter of approximately 2 cm), we managed it in the open abdomen without additionally exposing the patient to repeated cross-clamping. By tightly enveloping the aneurysm with a polyester band, we avoided additional time for another iliac exposure and anastomosis. Large-vessel polyester wrapping is frequently used in thoracic aorta repairs [18].

In conclusion, in cases of AAA with a clear indication for repair and an ectopic main renal artery arising from the aneurysmal sac, it is safe to consider special measures to protect the ipsilateral kidney from the anticipated in situ ischemia until the ectopic artery reconstruction and kidney reperfusion. Open surgical management is useful and thorough preoperative planning and intraoperative execution are mandated [19].

None.

The authors have nothing to disclose.

Concept and design: TK, PC. Analysis and interpretation: TK, PC. Data collection: all authors. Writing the article: all authors. Critical revision of the article: TK, PC. Final approval of the article: all authors. Statistical analysis: none. Obtained funding: none. Overall responsibility: TK, PC.