Mesoaortic Compression of the Left Renal Vein (Nutcracker Syndrome): Case Reports and Review of the Literature

Mesoaortic Compression of the Left Renal Vein (Nutcracker Syndrome): Case Reports and Review of the Literature Udo Rudloff, MD,1 Raymond J. Holmes, MD,1 Jeffrey T. Prem, MD,1 Glenn R. Faust, MD,1 Robert Moldwin, MD,2 and David Siegel, MD,3 New Hyde Park, NY

Compression of the left renal vein between the aorta and the superior mesenteric artery has been termed the nutcracker syndrome. Obstruction of left renal vein outflow results in venous hypertension with the formation of intra- and extrarenal collaterals and/or the development of gonadal vein reflux. To date, a variety of clinical symptoms due to mesoaortic compression of the left renal vein (nutcracker syndrome) have been described. It is not known what pathophysiological variables play a role in the different clinical manifestations of nutcracker syndrome. We report two patients representing the two different forms of the condition. In the first, hematuria and left flank pain resolved in a young man after successful renocaval reimplantation. In the second, symptoms of pelvic congestion due to pelvic varices improved in a middle-aged woman after successful embolization of the gonadal vein and pelvic collaterals. This report reviews the pathophysiology, presentation, diagnosis including radiographic findings, management options, as well as the current literature on nutcracker syndrome.

The term nutcracker syndrome (NCS) dates back to the anatomic description by Grant,1 who stated that ‘‘the left renal vein as it lies between the aorta and the superior mesenteric artery resembles a nut between the jaws of a nutcracker.’’ Although mesoaortic compression of the left renal vein (LRV) has been considered for decades to be the cause of varices associated with the ovarian vein syndrome,2,3 it was not until de SchepperÕs4 description of a 16-year-old boy studied for gross hematuria with selective venography that the observed extensive peri- and pararenal varicosities 1 Department of Surgery, Division of Vascular Surgery, Long Island Jewish Medical Center, Long Island Campus for the Albert Einstein College of Medicine, New Hyde Park, New York. 2 Department of Urology, Long Island Jewish Medical Center, Long Island Campus for the Albert Einstein College of Medicine, New Hyde Park, New York. 3 Department of Radiology, Division of Vascular and Interventional Radiology, Long Island Jewish Medical Center, Long Island Campus for the Albert Einstein College of Medicine, New Hyde Park, New York. Correspondence to: Udo Rudloff, MD, Deparment of Surgery, North Shore University Hospital, 300 Community Drive, Manhasset, NY 11030, USA, E-mail: [email protected]

Ann Vasc Surg 2006; 20: 120-129 DOI: 10.1007/s10016-005-5016-8 Ó Annals of Vascular Surgery Inc. Published online: January 1, 2006

120

and hematuria were linked to compression of the LRV. The term nutcracker syndrome was applied.4 The increased venous pressure within the renal circulation promotes the development of collaterals of the renal pelvis, and this plexus of abnormal hypertensive veins causes microhematuria or gross hematuria.5-7 Other possible symptoms include left flank pain,8 left-sided varicocele,3,9 pelvic congestion,10,11 chronic pediatric fatigue syndrome,12,13 orthostatic proteinuria,8,14 and gastrointestinal symptoms.15 A number of surgical procedures, including minimally invasive and endovascular approaches, have been described to alleviate LRV compression. Persistent venous hypertension in the LRV outflow, however, or matured connections between renal varices and the collecting system may lead, despite removal of the obstruction, to renal venous backflow and pelvic venous congestion or refractory hematuria and treatment failure.16,17 These cases might be better served with embolization of pelvic collaterals and varices or gonadocaval bypass.11,17 Here, we report our experience with the diagnosis and treatment of two cases of NCS. We critically examine and discuss the surgical options and review the current literature to emphasize an

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Fig. 1. A Ultrasonography shows dilatation of the distal part of the LRV (diameter 14 mm) with intrarenal collaterals. B Left retrograde pyelogram demonstrates blunting of calyces and indentations of the pelvicalyceal system suggestive of intrarenal varices.

Fig. 2. Axial section of contrast-enhanced abdominal CT at the level of the renal veins demonstrates marked compression of the LRV between the aorta and SMA (nutcracker phenomenon).

individually designed approach, taking the clinical and hemodynamic manifestations of this peculiar and rare condition into consideration.

CASE 1 A 17-year-old male was hospitalized in our unit for persistent hematuria and recurrent left flank pain of 6 monthsÕ duration. During this time, the patient had undergone repeat cultures of urine and excretory urography with negative results. On admission, gross hematuria was still present. The patient continued to have noncolicky left flank and lower abdominal pain aggravated by meals and change in position. Past medical and family history was noncontributory except for mild developmental delay. Physical examination was unremarkable except for very thin and tall body habitus. His weight was 47.5 kg and his height was 178 cm. Laboratory examinations were normal except for

moderate anemia, with hemoglobin level of 7 mg/ dl. Urinary red cell morphology showed 90% isomorphic red cells. Casts were absent and urine cytology was negative for malignancy. Renal Doppler ultrasonography showed dilatation of the distal part of the LRV and intrarenal venous collaterals (Fig. 1). Cystoscopy showed bleeding from the left ureteral orifice. Retrograde left urography revealed blunting and compression of renal calyces typical of intrarenal varices (Fig. 1). Computed tomography (CT) demonstrated compression of the LRV between the aorta and the superior mesenteric artery (SMA) (Fig. 2). The arterial phase of a selective renal angiogram was normal, but the venous phase showed bulbous dilatation of the midrenal vein with delayed flow into the inferior vena cava (IVC) and intrarenal varices with tortuous collateral vessels at the site of the pelviureteral junction (Fig. 3). Selective retrograde renal phlebography confirmed compression of the LRV at the level of the aorta (Fig. 3). Following retrograde LRV-IVC pullback pressure recording, a pressure gradient of 7 mm Hg was consistently demonstrated. Composite selective renal arterio- and venograms with three-dimensional reconstruction confirmed NCS by showing the pinching-off of the LRV as it courses between the aorta and SMA (Fig. 4). The patient initially refused surgery. He had frequent visits to the emergency department and several hospitalizations for symptoms of anemia due to intermittent severe hematuria requiring multiple blood transfusions. His pain persisted. One year after initial presentation, he underwent explorative laparotomy. The retroperitoneum was explored via a right mediovisceral rotation. The LRV was compressed between the aorta and SMA, which coursed proximally at a more acute angle than normal in the root of the mesentery. A groove in the anterior surface of the LRV was evident where it passed posterior to the SMA (Fig. 5). To

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Fig. 3. A Delayed venous phase of left renal arteriogram with abnormal bulbous dilatation of the LRV and engorged intrarenal varices. Note the absence of gonadal vein reflux. B Selective left renal venogram shows compression of the main LRV with dilated intrarenal collaterals. Pullback renocaval pressure gradient was 7 mm Hg.

clamped and the kidney cooled externally. Transposition of the LRV was performed by an end-toside anastomosis, and after restoration of renal circulation, the upper caval venostomy opening was closed with a running polypropylene suture (Fig. 5). The patient had an uneventful postoperative course. He was asymptomatic and free of hematuria during a 1.5-year follow-up, with resolution of his fatigue. Repeat renal ultrasonography revealed normalization of LRV measurements and resolution of intrarenal varices.

CASE 2

Fig. 4. Composite left renal arteriogram and venogram displays anatomic configuration of NCS.

relieve the compression, the SMA was dissected off the LRV. The left inferior adrenal vein, small perihilar varices, and lumbar veins draining into the LRV were ligated and transected. Following placement of a Satinski clamp, the IVC was opened laterally 5 cm inferior of the confluence of the LRV, keeping clear of the origin of the inferior mesenteric artery (IMA). The left renal artery was

A 64-year-old woman presented with pelvic pain, dyspareunia, and intermittent hematuria of 2 yearsÕ duration. Initially, the patient reported the pain to be aggravated by long periods of standing and to be worse at the end of the day. When the patient was referred to our institution, the pain had worsened with any type of upright activity, including sitting. Past medical history was noncontributory except for total abdominal hysterectomy 4 years prior. Physical examination revealed no abnormalities except tenderness in the left vaginal fornix on pelvic examination. Laboratory tests were within normal limits. Initial investigations including repeat cultures of urine, urine cytology, and cystoscopy with bladder biopsy were without abnormal findings. Ultrasonography of the urinary tract and excretory urography were normal. Repeat cystoscopy showed bleeding from the left ureteral orifice. CT of the abdomen demonstrated LRV compression between the SMA and the abdominal aorta and extensive pelvic varices filling the entire left broad ligament (Fig. 6). Transfemoral left renal venography performed with a 5 Fr. catheter showed near obstruction of the LRV with severe backflow into

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Case reports 123

Fig. 5. Transposition of the LRV. A Groove at the left renocaval junction (arrow) at site of compression by SMA (reflected cephalad). B LRV transposed 4 cm inferiorly, keeping clear of the IMA.

minimal filling of varices were identified after the injection, and subsequently a total of nine microcoils were placed in the lower and middle aspects of the gonadal vein. Completion venography demonstrated successful occlusion of these vessels. Six months after the procedure, the patient reported near complete resolution of her pelvic pain.

DISCUSSION

Fig. 6. Contrast-enhanced CT of the abdomen demonstrates large varices along the pelvic sidewalls (arrows), which are more pronounced on the left.

the lumbar veins and gonadal vein reflux (Fig. 7). The dilated ovarian vein with perirenal and periureteral collaterals drained into large pelvic varicosities (Fig. 7). Renocaval pullback pressure gradient measurements revealed a 6.7 mm Hg gradient across the renal vein. On the basis of these findings, a diagnosis of pelvic congestion syndrome secondary to NCS was made. Utilizing a 2.8 Fr. coaxial microcatheter through the 5 Fr. catheter, the left gonadal vein was descended to the level of the pelvis and venography performed, demonstrating a tangle of varices on the left pelvic side wall/periovarian region. During injection into these varices, the patient complained of pain similar to that of her chief complaint. The catheter was advanced farther distally, and 2 cc of sodium morrhuate solution (50 mg/cc) was injected during withdrawal of the catheter to the upper aspect of the varices. Marked spasm and

Vascular surgeons treat various vascular compression syndromes, including thoracic outlet, celiac axis, and May-Thurner syndrome. NCS, or mesoaortic compression of the LRV, one of the rarest and most intriguing, has not been recognized with similar attention by our specialty. It typically presents with hematuria, with or without left flank pain. The majority of afflicted patients are young (Table I). Varicocele is not an uncommon finding in young males.9,18,19 There is a second peak of NCS occurring in middle-aged women. These patients frequently present with symptoms of pelvic venous congestion due to massive gonadal vein reflux and pelvic varices.10,11,20-23 The left side is involved 90% of the time, and bilateral varices have been reported in 4% of cases.11,24 Microscopic hematuria is a common finding in these patients, while only a third complain about left flank pain.11,20,24 Whether these two different clinical pictures reflect different stages of the disease requiring different surgical approaches is so far not known. It has now been accepted that an abnormality within the configuration of the origin of the SMA from the aorta constitutes the congenital cause of this syndrome. Hohenfellner et al.16 demonstrated, using sagittal magnetic resonance imaging (MRI) investigations in three patients with NCS, an initial steep caudal descent of the SMA causing compression of the LRV in the narrow slit between the aorta and SMA. This finding is in contrast to a

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Fig. 7. Retrograde catheterization of the gonadal vein. A LRV is not opacified, suggestive of renal venous hypertension. A large gonadal vein measuring 10-12 mm (normal 3-4 mm) is noted, filling the paravertebral venous plexus. B Gonadal venous reflux has led to the formation of extensive pelvic and adnexal varicosities.

nearly rectangular configuration in 10 volunteers where the SMA ran a course of about 4-5 mm in the ventral direction before its caudal descent.16 Shokeir et al.18 confirmed these findings in three patients with angles between the aorta and the SMA of 42, 47, and 51 degrees compared to the usual rectangular branching in 12 healthy donors. However, the observation of LRV obstruction on plain imaging does not prove the existence of hemodynamic significance and should not automatically lead to the diagnosis of NCS since only a minority of patients with LRV compression develop clinical symptoms of NCS.25,26 The primary diagnostic test should therefore be the clinical examination. If a patient has symptoms of hematuria and pelvic congestion, the association of left-sided flank pain, pelvic discomfort, and pelvic and vulvar varices in the female and varicocele in the male constitute a strong basis for the diagnosis. Duplex ultrasonography, MRI, or CT, which can visualize LRV compression, should be the next diagnostic step. Excretory or retrograde urography is abnormal in about half of the cases,24 often showing indentations and scalloping of the renal pelvis or the ureter from compression by varices.10,19,24 However, renal angiography and retrograde venography remain the standards for diagnosis. The arterial phase of the renal angiogram is usually normal, and the delayed venous phase may show dilatation of the LRV with dilated intra- and perirenal collaterals. The definite documentation of NCS should be the contrast visualization of the renal and gonadal vein system and its pelvic and extrapelvic connections on selective venography with renocaval pressure gradient determination. A pressure gradient of less than 1 mm Hg between the distal LRV and the IVC was found in 49 of 50 normal individuals in the landmark study by Beinart et al.27 Zerhouni et al.9 noted renocaval pressure gradients of 17, 16, and 4 mm Hg in three patients with NCS, whereas the gradient in five

normal controls ranged 0-3 mm Hg. Nishimura et al.28 regarded a pressure gradient of 3 mm Hg or more as indicative of LRV hypertension. However, there is still no clear agreement as to the cut-off value with which NCS should be diagnosed.16,29,30 Normal ranges may vary between 3 and 10 cmH2O, and pressure gradients in patients with NCS may range between 4.9 and 14 cmH2O.16 There are reports of the usefulness of color Doppler ultrasonography in the diagnosis of NCS. The sensitivity and specificity for revealing NCS were 78% and 100%, respectively, when color flow in collateral veins was included.31 At that point, we feel a diagnosis of NCS should not be made without knowing the hemodynamic significance of an observed LRV compression; therefore, we have not included reports without renocaval pressure gradient determination in Table I. How does compression of the LRV lead to symptoms of hematuria and left flank pain, and do the different manifestations of NCS have different pathophysiological causes? In its purest form, NCS is described as LRV compression between the aorta and SMA. This outflow obstruction causes elevated LRV pressure. One of the first compensating mechanisms is the development of new, valveless venous collaterals to increase venous capacitance and drainage. Assuming that the valves of the gonadal, inferior adrenal, and lumbar veins remain competent and there is no significant reflux into these veins, a situation of LRV hypertension will persist. A high renocaval pressure gradient will be detectable. The careful work of MacMahon and Latorraca,5 Pytel,6 and Low and Matz7 proved histologically in this situation direct channels of communication between the lumen of dilated, extremely thin-walled venous sinuses, and adjacent calyces in cases of essential hematuria. The walls of these communicating channels were lined in part by endothelium and in part by transitional epithelium. Left flank pain may be caused by the

2001

2001

2000

2000

1999

1997

1998

1997

Igari26

Takahashi et al.13

Park et al.47

Segawa et al.46

Russo et al.49

Hilgard et al.15

Itoh et al.51

2002

Scultetus et al.11

1

2002

Andrianne et al.23 Chen et al.48

1

1

2

1

1

9 (11-14)

19

9

8

1

2003

Ali-El-Dein et al.34

2002

8

Year

Author

Hohenfellner et al.17

Pts. (n)

27

22

20, 20

40

47

12

24 (18-32)

35.5 (28-46)

39.1 (23-58)

25

58

31.5 (mean)

Age (years)

0/1

1/0

0/2

0/1

1/0

1/8

NS

0/9

4/4

0/1

0/1

NS

Sex (M/F)

2 (25%)

1

1

8 (100%)

Pain [n (%)]

?

1

0

2

1

0

1

0

0

0 0 All patients investigated for chronic fatigue 1 0

19 (100%)

9 (100%) 9 (100%) All patients investigated for pelvic syndrome congestion

8 (100%)

1

1

NS

Hematuria [n (%)]

2nd trimester of pregnancy

Asthenic habitus, chronic fatigue

Previous left varicocelectomy

2 With orthostatic proteinuria

Scrotal varices in most men

3 Vulvar varices 2 Gluteal varices 4 Lower extremity varices

NS

Thin body habitus

NS

Physical exam (external varices)

Table I. Reported cases of NCS with renocaval pressure gradient determination

18 Patients with collaterals in intraand extrarenal location 4 Patients with extrarenal collaterals/varices Hilar varices and collaterals at ureteropelvic junction Multiple collateral channels Intrarenal varices in both Peripelvic varices with retrograde flow into testicular vein Increased collateral blood flow

All patients with perirenal varicosities with reflux into ovarian vein filling extensive pelvic and vulvar collaterals

Peripelvic and periureteric varices and gonadal vein reflux Entrapment of LRV between aorta and SMA

Perirenal and periureteric collaterals with gonadal vein reflux Reflux into collaterals

Selective venogaphy (internal varices)

3.5 cm H2O

5.0 and 7.0 cm H2O 15

5 cm H2O

3

5.6 (3-7) in 5 cases

>3 in 13 patients

4-14

12.8 ± 2.7 (8-14)

6.8 cm H2O

4 cm H2O

9.5 cm H2O (mean)

RCG [mean (mm Hg)]

(Continued)

Nonoperative aggravation during pregnancy

Renocaval reimplantation

Endovascular placement of Niki stent Endovascular stent placement Refused surgery

NS

1 Nephrectomy after 6 years for persistent hematuria 2 External stenting (PTFE ring) 1 Endovascular placement of Palmaz balloon stent 3 Gonadocaval bypass (Dacron) NS

8 Transposition of LRV

Venolysis + augmentation plasty Lost to follow-up

6 Renal autotransplantation

Treatment (n with intervention)

Vol. 20, No. 1, 2006 Case reports 125

1997

1997 1996

1994 1994

1994

1990

1988

1986 1983 1982

1980

1980

1978

1972

Chuang et al.50

Lee et al.14 Neste et al.45

Ishidoya et al.52 Shaper et al.19

Shokeir et al.18

Ariyoshi et al.33

Barnes et al.24

Dever et al.22 Weiner et al.21 Stewart et al.29

Zerhouni et al.9

Wendel et al.20

Coolsaet10

de Schepper4

2

21

1

3

1 1 3

1

1

3

1 5

2 1

1

Pts. (n)

16, 58

NS

45

15, 16, 34

40 20 33 19, 24

17

20

37

38 25 (21-35)

11,12 58

27

Age (years)

2/0

0/21

0/1

3/0

0/1 0/1 1/2

0/1

1/0

1/2

1/0 2/3

0/2 1/0

0/1

Sex (M/F)

RCG, renocaval gradient (mmHg); NS, not stated.

Year

Author

Table I. Continued

1

Pain [n (%)]

Physical exam (external varices)

1

0

1

0

1 1 2 (67%)

1

1

?

21 (100%)

1

0

0 1 3 (100%)

1

0

NS

All 3 patients investigated for left varicocele Asthenic build

Thin body habitus

Thin and above average height

Orthostatic proteinuria in both patients 1 0 Previous pancreatic surgery and radiation 1 1 Thin stature 5 (100%) 5 (100%) Left varicocele in 1 patient, all above average height 3 (100%) 3 (100%) Left varicocele in male patient

1

Hematuria [n (%)]

Extensive perirenal and periureteric vein plexus with collaterals

Dilated periureteral veins with gonadal vein reflux 12 Periureteric varices with gonadal vein reflux

Reflux into gonadal vein Left ovarian vein reflux 2 Renal varices with perirenal and periureteric collaterals

Periureteral varices

Perirenal and periureteric collaterals with gonadal reflux No collaterals

Perirenal varices Perihilar varices in all 5 patients

Collateral veins Multiple collateral channels

Dilated left gonadal vein

Selective venogaphy (internal varices)

Positive but values NS

Positive in all 21 patients but values NS

7 cm H2O

17, 16, 4

5 5 cm H2O 6.3, 6.0, and 5.5 cm H2O

12

8.2 cm H2O

8, 11, 12 cm H2O

6 cm H2O > 3 in all 5 patients

18 and 10 18 cm H2O

4.8 cm H2O

RCG [mean (mm Hg)]

12 Ligation of upper renoureteral varices with selective gonadal vein resection and nephrectomy

Anterior nephropexy with ligation of collaterals

Renocaval reimplantation with placement of synthetic wedge External stenting of LRV with PTFE ring Nonoperative Nonoperative 3 Transposition of LRV and resection of collateral vessels NS

Renocaval reimplantation 4 LRV transposition, 1 LRV Gortex interposition, graft interposition 2 autotransplantation of left kidney

Renal autotransplantation NS Endovascular placement of Wallstent

Treatment (n with intervention)

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passage of blood or clots. A peak of NCS occurrence can be observed during adolescence and early adulthood, commonly presenting with hematuria and left flank pain or with constitutional symptoms like chronic fatigue, as in our patient (see Table I). The overrepresentation of thin and asthenic patients in this group has been previously noted, and body habitus, amount of retroperitoneal fat, and pattern of body development might be contributory factors.8,13,20 Wendel et al.20 hypothesized that stretching of the LRV over the aorta and dorsal ptosis of the left kidney in the supine position due to lack of retroperitoneal fat contribute to LRV compression. Interestingly, it is in this group of patients that, if symptoms permit, expectant management without operative intervention often leads to spontaneous resolution of symptoms.10,16,18,19 On the other hand, there is a subset of patients, mainly middle-aged women, where NCS presents with symptoms of pelvic venous congestion, like chronic pelvic pain, dyspareunia, dysuria, or dysmenorrhea.11,20-23 Venography reveals massive gonadal vein reflux leading to the development of pelvic, vulvar, and even lower extremity varices.11 In these cases, long-standing LRV hypertension has led to valvular incompetence and venous insufficiency of the gonadal and lumbar veins. Decompression of the LRV through its collaterals and reflux into the gonadal vein system have occurred. These patients rather show an increased renal venous baseline pressure with a low pressure gradient. Do these clinicopathological observations have implications for the treatment of patients with NCS? Nearly all surgical approaches aim to relieve the LRV outflow obstruction. Surgical modalities include LRV bypass with polytetrafluoroethylene (PTFE) graft interposition and reanastomosis to the IVC anteriorly.19 Autotransplantation of the left kidney has been performed by Shokeir et al.18 with satisfying results. The left kidney was reimplanted into the left iliac fossa, and hematuria ceased in all patients. Mesoaortic transposition, described by Thompson et al.,32 was not repeated in published studies. The low morbidity of renal vein-related procedures and the potential disastrous complications related to impaired blood flow within the SMA prevented acceptance of this technique. The so far most frequently reported procedure is transposition of the renal vein with33 or without16,17,19,29 additional placement of a synthetic wedge. It requires only limited exposure of the retroperitoneum and avoids an additional anastomosis. Its renal ischemia time is shorter than in autotransplantation of the kidney. Although it is an

Case reports 127

efficient and safe procedure, Hohenfellner et al.17 described in a series of eight patients one treatment failure requiring nephrectomy after 6 years because of recurrent hematuria. The persistent hematuria and failed normalization of renocaval pressure gradients were explained by the maturity of significant shunts between the LRV and the collecting system and transformation and fixation into a highpressure system.17 In this regard, renal autotransplantation with its disconnection from renal vein contributories may offer maximal efficacy in terms of normalization of renal venous circulation.17,34 However, the majority of reports describe resolution or improvement of clinical symptoms.17,19,29,33 A different situation, we think, exists in patients who predominantly present with pelvic venous congestion due to massive gonadal vein reflux. In his landmark contribution, Coolsaet10 recognized that ligation of collateral vessels might increase the renocaval pressure gradient in patients with NCS after abolition of its draining channels and proposed bypass of the venous compression as the procedure of choice. Scultetus et al.11 observed that patients with massive gonadal vein reflux undergoing renal bypass did not have similar improvements in their symptoms. This subset of patients, in addition to relief of the obstruction, requires either ablation or an additional drainage procedure of the pelvic varices.11,35 In this situation, a gonadocaval bypass can serve as both an outflow for the obstruction of the gonadal system and an accessory drainage pathway for the renal vein. This type of approach has been used successfully in mesocaval anastomosis (H graft) for the treatment of portal hypertension. Scultetus et al.11 reported the successful use of this method in three patients with severe gonadal vein reflux using a 5 mm DacronTM segment. More recent reports raise enthusiasm for minimally invasive and endovascular treatment modalities of NCS. Initially performed via a transperitoneal approach, a PTFE ring-forced external stent can be wrapped around the renal vein to prevent its compression by the mesoaortic clamp.11,24 The procedure has now also been performed by laparoscopic surgery.11 However, the risk of erosion of adjacent structures and dislodgment of the stent has not been defined yet. There are five reports of an endovascular approach to NCS. The use of endoluminal stents in the venous system to correct stenotic segments stems from optimistic results in the treatment of CockettÕs or May-Thurner,36-39 superior vena cava,40 thoracic outlet,41 and Budd-Chiari syndromes and the treatment of venous stenosis in patients undergo-

128 Case reports

ing hemodialysis.42-44 The first report of the use of an expandable metallic stent in the renal vein for NCS was described by Neste et al.45 A 42 mm Wallstent was deployed to reduce the gradient between the LRV and the IVC from 8 to 3 cmH2O. Segewa et al.46 placed a 7 cm long, 20 mm diameter metallic stent at the site of mesoaortic compression. The renocaval gradient disappeared, and the hematuria of the patient resolved. Park et al.47 used an 18 mm diameter Niki stent and Scultetus et al.,11 a 60 mm Palmaz balloonexpandable stent. In the absence of long-term experience, intimal fibromuscular hyperplasia leading to venous thrombosis is a feared complication. The venous system is particularly prone to thrombosis, and the revision of two cases of NCS treated with endovascular stenting after 4 years has been recently reported.11 Another complication is retrograde thrombosis extension and proximal embolization. In the first patient, our choice of direct renal vein transposition was guided by two considerations. First, we felt that we were dealing with an ‘‘early’’ form of NCS. The young age of the patient, the presence of symptoms for 6 months, the absence of varicocele, and documented pelvic vein reflux via testicular vein reflux on retrograde phlebography did not indicate renal vein compression with hemodynamic venous decompensation or formation of a renal venous high-pressure system. Correction of the venous outflow seemed sufficient to expect a successful outcome. Second, the young age of the patient and the absence of long-term data on the safety of external or internal stenting procedures led us favor direct renocaval reimplantation. In our second patient, long-standing LRV hypertension led to severe gonadal vein reflux with development of pelvic varices. Fixed renal venous hypertension was likely, and solely correction of the outflow obstruction seemed unlikely to diminish reflux and collateral blood flow and to improve the patientÕs symptoms. Embolization of the gonadal vein system and pelvic varices led to near complete resolution of the patientÕs symptoms. In conclusion, the diagnosis of NCS should be considered on the basis of a thorough clinical examination in patients with hematuria, left flank pain, varicocele, and symptoms of pelvic venous congestion. Compression of the LRV between the SMA and aorta observed on ultrasonography, CT, or MRI should alert the physician to consider the diagnosis. If the symptoms merit, in particular if cystoscopy demonstrates left ureteral hematuria, selective left renal venography with pullback

Annals of Vascular Surgery

determination of renocaval pressure gradient is the diagnostic test of choice and should be performed in all patients. Elevated LRV baseline pressure with massive gonadal vein reflux into peripelvic varices might indicate transformation into a high-pressure venous system. These cases are best served with embolization of the varices. Alternatively, drainage procedures of the gonadal vein system like gonadocaval bypass are efficient at improving symptoms due to pelvic congestion. Relief of outflow obstruction of the LRV is the main goal of treatment in all other cases. Direct renocaval reimplantation of the LRV seems to be the procedure preferred by most surgeons to date. Renal autotransplantation may offer maximal efficiency in terms of normalizing renal venous circulation. External and internal stenting procedures by either minimally invasive or endovascular approaches are promising treatment options. The rarity of described cases with an absence of long-term followup limits its use at this point. Indications for surgical and radiological interventional methods should be guided closely by the clinical and radiological findings as different manifestations due to different stages of the disease may require additional interventions.

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