Left Renal Vein Obstruction


Article Author:
Muhammad Hanif


Article Editor:
Sandeep Aggarwal


Editors In Chief:
Stephen Leslie
Karim Hamawy


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Trevor Nezwek
Radia Jamil
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
6/4/2019 4:53:49 PM

Introduction

Left renal vein obstruction, also known as Nutcracker phenomenon (NCP), occurs due to the external compression of the left renal vein (LRV) in between the angle formed by the origin of the superior mesenteric artery (SMA) from the aorta. The word "Nutcracker" was first used by Chait et al. in 1971, but in 1972, the Belgian physician De Schepper named it after his observation of the compression of LRV between the aorta and SMA which behave as 2 levers of the Nutcracker.[1][2]

Etiology

LRV compression is a developmental anomaly. It occurs when the average angle between the SMA and the aorta of approximately 90 degrees reduces to less than 35 degrees.[3] This leads to the NCP. The term Nutcracker syndrome (NCS) is interchangeably used with NCP when clinical symptoms accompany the anatomical findings. The LRV courses in front of the aorta before draining into the inferior vena cava. It has an extended course of 6 to 7 cm compared to 3 to 4 cm of the right renal vein. There have been several arterial and venous anomalies associated with NCS. Venous anomalies include LRV bifurcation with branches coursing in front and back of the aorta. The LRV compresses between the aorta and vertebral body in cases where it takes a retro-aortic route leading to posterior NCS.[4] Arterial anomalies include the low or lateral origin of the SMA from the aorta leading to the most common type of compression between the SMA and aorta which is known as anterior Nutcracker syndrome. Anterior NCS can also co-exist with compression of the duodenum as part of the Wilkie syndrome (SMA syndrome). Excessive fibrous tissue along the origin of SMA which compresses the left renal vein. Les frequently, LRV can be externally compressed by pancreatic neoplasm, para-aortic lymphadenopathy, retroperitoneal tumor, and abdominal aortic aneurysm.[3]

Epidemiology

The exact prevalence of Nutcracker syndrome is unknown. Although it is more common in women especially in the second and third decade of life as suggested by the reported cases, it can occur from first to the seventh decade of life. A low body mass index (BMI) has shown a positive association with the NCS, due to the rapid increase in body height and vertebral bodies maturation during puberty leading to narrowing of the angle between SMA and Aorta.[5] It is not a hereditary phenomenon, but coincidental cases in siblings have been reported.

History and Physical

Clinical manifestations differ widely among patients with NCS, but the most common complaint is hematuria with or without flank pain. Presentation in children is usually asymptomatic hematuria. In the female, it often presents with pelvic congestion syndrome with associated symptoms of dysmenorrhea, dyspareunia, dysuria, lower abdominal pain, post-coital pain, varices (gluteal/thigh) and emotional disturbance.[6] Other presentations include orthostatic proteinuria and varicocele in males.

Hematuria occurs in the background of rupture of thin-walled varices into the collecting system secondary to venous congestion and hypertension. Hematuria can be macroscopic or microscopic which can lead to resultant anemia. Pain is part of the pelvic congestion syndrome and can be aggravated by sitting, walking or riding in a vehicle. Sometimes, Left flank pain could be due to the passage of blood clots in the ureter leading to ureteric colic. Orthostatic proteinuria occurs more in puberty. Increased LRV pressure along with subclinical immune injury is thought to be the mechanism behind it. Left-sided varicoceles secondary to the Left renal vein hypertension occur in males.[2]

Evaluation

The path to diagnose NCS is often a difficult one, and most of the times it comes under the diagnosis of exclusion. The workup is usually related to the presentation of typical Hematuria which includes urinalysis, urine culture, cystoscopy, ureterorenoscopy, and even renal biopsy. The vascular anomaly can then be ruled out by doing ultrasound imaging and color Doppler scanning which has a sensitivity of 78% and specificity of about 100%. The anteroposterior diameter and peak velocities of LRV should be measured at 2 points in the transverse plane. First, at the level of renal hilum and second, when it crosses the aorta and SMA. When the peak velocity and AP diameter at these 2 points exceed by factor 5, the diagnosis should be suspected of NCS. Then further workup should be done by CT angiography or MRA to define the anatomical relation of LRV to aorta and SMA. With MRA being superior to CTA due to the fact of absence of radiation and having multi-planer imaging.[7] Anatomical abnormalities that could be found include an abnormal origin of SMA, an abnormal high course of LRV, dorsolateral torsion of the L kidney, abnormally low or lateral origin of the SMA.

The gold standard then to establish the final diagnosis is by doing the cine-video angiography and retrograde phlebography along with reno-caval pressure gradient measurement. The normal mean pressure gradients range from 0 to 1 mm Hg. To establish the diagnosis of NCS, the pressure gradient between the left renal vein and IVC should be greater than 3 mm Hg. The advantage of cine-video angiography is not only it allows visualization of LRV compression at the level of crossover between aorta and SMA, but it also shows reflux of collaterals into the adrenal and gonadal veins with stasis of contrast in the renal vein.[8]

Treatment / Management

Since NCS is uncommon, management over the recent decades has been a subject of debate, and it varies a lot depending on the symptoms and age of the patient. Young patients who are in their adolescence with short periods of mild hematuria and insignificant pain can be observed without any treatment for at least 2 years as with physical development the increase in fat and fibrous tissue relieve the LRV obstruction.[9] In patients with orthostatic proteinuria ACE inhibitors have a role in improving it.[10] On the other hand, patients who are symptomatic with flank pain and hematuria can be tried for different surgical options ranging from intravascular or extravascular stenting, intrapelvic chemical cauterization and open surgical procedures such as nephrectomy to renal autotransplant.

Pastershank did the first surgical procedure in 1974. It involved renal vein release via cutting through the fibrous tunnel between aorta and SMA. The most reported procedure was LRV transposition which included separation of the LRV at its convergence with the inferior vena cava and reanastomosis of the excised LRV at a lower level of IVC incision aside from the SMA. Transposition of SMA has the similar type of principal as LRV transposition has that is the division of SMA from its origin of aorta and reanastomosis at a lower level away from LRV, but it has a risk of intestinal ischemia which explains its avoidance nowadays.[11] Renal autotransplant which has wide surgical exploration is more invasive than LRV transposition.[12][13]

Intravascular and extravascular stenting have been applied recently. Extravascular stenting utilizing a ring polytetrafluoroethylene graft is used by open surgery after mobilization of the duodenum the PTFE ring is applied around the LRV. During Intravascular stenting the endograft is being delivered to the narrow portion of the LRV via the femoral vein. Some of the complications of stenting include stent migration, restenosis, and embolization.[14][15]

Pearls and Other Issues

NCS remains underdiagnosed, and a  proper understanding of NCS or NCP is essential to keep it in mind when seeing a patient with clinical symptoms and signs of hematuria, pelvic pain, pelvic varicosities, and varicoceles. Lack of knowledge of the natural history of this condition leads to improper diagnostic criteria and treatment. Patients who are in their adolescence with a benign course require a more conservative approach as they will outgrow their symptoms with physical development. Those with severe symptoms require vascular intervention or surgery to treat the condition.[12]

Enhancing Healthcare Team Outcomes

Left renal vein occlusion is a rare disorder that is difficult to diagnose. Because of its diverse presentation and complexity in diagnosis, it is best managed by a multidisciplinary team that includes nurses and pharmacists. Since NCS is uncommon, management over the recent decades has been a subject of debate, and it varies a lot depending on the symptoms and age of the patient. Young patients who are in their adolescence with short periods of mild hematuria and insignificant pain can be observed without any treatment for at least 2 years as with physical development the increase in fat and fibrous tissue relieve the LRV obstruction.[9] In patients with orthostatic proteinuria ACE inhibitors have a role in improving it.[10] On the other hand, patients who are symptomatic with flank pain and hematuria can be tried for different surgical options ranging from intravascular or extravascular stenting, intrapelvic chemical cauterization and open surgical procedures such as nephrectomy to renal autotransplantation. Recently endovascular stenting has been attempted but the procedure has been associated with stent dislodgment and migration.

The outcomes remain unknown because of the few cases and lack of controlled trials.


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Left Renal Vein Obstruction - Questions

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During surgery in a patient with an abdominal aortic aneurysm, the left renal vein is engorged but the left kidney appears normal. What vessel must be examined in such a scenario?



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A 30-year-old African American female with past medical history of hypertension has had hematuria for 2 weeks. CT scan of the abdomen revealed narrowed angle between the superior mesenteric artery and the aorta of 32 degrees with normal being 90 degrees. The distance measures 5 mm with normal more than 8 mm, and the interventional radiology venogram revealed a pressure gradient across the area of compression of 1 mmHg (normal less than 1 mmHg) suggestive of left renal vein hypertension. What should be the next step in the management of this patient?



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A 35-year-old female with past medical history of gastroesophageal reflux disease came to the office because of left sided flank pain since one month. The pain is without fever, chills and burning micturition. Which radiologic investigation would be the next best step if nutcracker syndrome is suspected?



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What is the most common anatomical manifestation that leads to left renal vein obstruction?



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What is the angle between the superior mesenteric artery and aorta which causes compression of the left renal vein leading to increased risk of having nutcracker phenomenon?



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A 24-year-old male presents with the complaint of severe vomiting, epigastric pain and bloating since 4 days. On clinical examination, the patient was underweight with a BMI of 16 kg/m2 with upper abdominal tenderness. Initial laboratory workup was negative. Ultrasound abdomen didn't show any sonographic abnormality. CT scan abdomen was performed with contrast which showed dilated proximal duodenum with narrowing of the third part of the duodenum between the angle of Aorta and superior mesenteric artery (SMA) and decreased aortomesenteric angle of 17 degrees. Also, there was compression of the left renal vein. Upon further questioning, the patient had a history of intentional weight loss to pursue a career in modeling. There was no history of hematuria or proteinuria. After conservative pain management and fluid resuscitation, his symptoms improved. The patient was concern about future episodes of abdominal pain on discharge. What should be the ideal approach in the management of this patient?



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Left Renal Vein Obstruction - References

References

A systematic review on management of nutcracker syndrome., Velasquez CA,Saeyeldin A,Zafar MA,Brownstein AJ,Erben Y,, Journal of vascular surgery. Venous and lymphatic disorders, 2017 Dec 29     [PubMed]
Left Renal Vein Compression Syndrome: Cracking the Nut of Clinical Dilemmas - Three Cases and Review of Literature., Siddiqui WJ,Bakar A,Aslam M,Arif H,Bianco BA,Trebelev AE,Kelepouris E,Aggarwal S,, The American journal of case reports, 2017 Jul 6     [PubMed]
Endovascular stent placement for nutcracker phenomenon., Li H,Sun X,Liu G,Zhang Y,Chu J,Deng C,Zhou B,Chen W,Yang J,, Journal of X-ray science and technology, 2013     [PubMed]
Extravascular stent management for migration of left renal vein endovascular stent in nutcracker syndrome., Tian L,Chen S,Zhang G,Zhang H,Jin W,Li M,, BMC urology, 2015 Jul 24     [PubMed]
Nutcracker Syndrome with Pelvic Congestion: A Case Report., Ito K,Ookawara S,Ueda Y,Morishita Y,, Internal medicine (Tokyo, Japan), 2017 Oct 15     [PubMed]
Nutcracker phenomenon and nutcracker syndrome., Kurklinsky AK,Rooke TW,, Mayo Clinic proceedings, 2010 Jun     [PubMed]
ACE inhibition can improve orthostatic proteinuria associated with nutcracker syndrome., Ha TS,Lee EJ,, Pediatric nephrology (Berlin, Germany), 2006 Nov     [PubMed]
Current trends in the diagnosis and management of renal nutcracker syndrome: a review., Ahmed K,Sampath R,Khan MS,, European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery, 2006 Apr     [PubMed]
Spontaneous remission of persistent severe hematuria in an adolescent with nutcracker syndrome: seven years' observation., Tanaka H,Waga S,, Clinical and experimental nephrology, 2004 Mar     [PubMed]
Magnetic resonance angiography in nutcracker phenomenon., Kaneko K,Ohtomo Y,Yamashiro Y,Obinata K,Kurokawa S,Aizawa S,, Clinical nephrology, 1999 Apr     [PubMed]
["Nutcracker" phenomenon of the renal vein and venous pathology of the left kidney]., de Schepper A,, Journal belge de radiologie, 1972 Sep-Oct     [PubMed]
Oh MJ, Superior Mesenteric Artery Syndrome Combined with Renal Nutcracker Syndrome in a Young Male: A Case Report. The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi. 2017 Dec 25;     [PubMed]
Reed NR,Kalra M,Bower TC,Vrtiska TJ,Ricotta JJ 2nd,Gloviczki P, Left renal vein transposition for nutcracker syndrome. Journal of vascular surgery. 2009 Feb;     [PubMed]
Park JH,Lee GH,Lee SM,Eisenhut M,Kronbichler A,Lee KH,Shin JI, Posterior nutcracker syndrome - a systematic review. VASA. Zeitschrift fur Gefasskrankheiten. 2018 Jan;     [PubMed]
Pinto Sousa P,Machado R,Sá Pinto P,Almeida R, Renal Autotransplantation - The Solution for Different Pathologies. Revista portuguesa de cirurgia cardio-toracica e vascular : orgao oficial da Sociedade Portuguesa de Cirurgia Cardio-Toracica e Vascular. 2017 Jul-Dec;     [PubMed]

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