Renal vascular malformations and compression

　　1. Etiology

　　The etiology of renal vascular malformation and compression can be divided into congenital and acquired types. Congenital renal vascular malformations and variations are difficult to differentiate. Usually, 'malformation' refers to morphological and structural abnormalities accompanied by functional disorders and pathological changes; while 'variation' refers to morphological and structural abnormalities without affecting organ function or causing pathological changes. Certain variations of renal vessels may also cause pathological changes under specific conditions, and renal vascular malformations may not constitute pathological changes. For example, some small branch renal arteriovenous fistulas generally do not affect health, but when female patients are pregnant, due to increased blood flow, they may lead to high cardiac output heart failure. The etiology of congenital renal vascular malformations is not yet clear, and it may be due to chromosomal abnormalities caused by certain viral infections during embryonic development, or DNA recombination errors during cell division. Acquired factors include trauma, tumors, etc.

　　2. Pathogenesis

　　Currently, it is generally believed that the pathogenesis of the disease includes: First, due to the fact that the left renal vein enters the inferior vena cava through the gap between the superior mesenteric artery and the abdominal aorta, it is pinched during the passage, causing obstruction of renal venous return, leading to increased pressure in the renal venous system, formation of collateral veins in the renal and perirenal veins, varicose deformation, and in severe cases, rupture and bleeding, causing hematuria. Second, congenital renal artery is small or absent, originating from other secondary branches of the abdominal aorta or fibromuscular dysplasia of the renal artery, or acquired compression of the main trunk or branches of the renal artery, leading to increased arterial pressure and decreased renal blood flow. All these reasons can cause a decrease in blood flow to varying degrees, leading to ischemia of juxtaglomerular cells near the glomerular artery, releasing renin, and increasing the activity of the renin-angiotensin system, causing hypertension.

　　Renal arteriovenous fistula and renal vein compression increase renal intravenous pressure, leading to edema and congestion of the renal collecting tubules or renal trauma, abscesses, etc., causing renal vascular rupture, involving the renal collecting system, and thus resulting in hematuria and proteinuria.

　　They often cause hematuria, proteinuria, renal colic; patients may develop hypertension and heart failure due to decreased renal blood flow. Severe or advanced cases may present with azotemia, and cases of death from uremia are reported less frequently. Patients with acquired renal arteriovenous malformations and compression may have symptoms and signs of the primary disease. Severe cases may cause acute heart failure, which is life-threatening.

　　Clinical symptoms and signs of renal vascular malformation and compression are non-specific. Generally, they are influenced by the severity of hemodynamic changes in the affected kidney, and they also vary depending on whether the lesion damages the renal collecting system. Common clinical manifestations include the following:

　　1, Hidden pain in the lumbar costal region:主要以闷痛，胀痛为主, rarely accompanied by renal colic, physical examination shows tenderness and percussion pain in the affected side of the lumbar or abdominal back or in the renal area.

　　2, Hypertension:Patients may develop secondary hypertension due to decreased renal blood flow, most of whom appear moderate to severe refractory hypertension 1 to 2 weeks after onset. Congenital renal vascular malformation or compression, patients may onset in infancy or adolescence, and physical examination may find vascular murmurs on both sides of the upper abdominal midline or in the lumbar region in some patients.

　　3, Renal collecting duct involvement:It often causes hematuria, proteinuria, and generally mild renal function damage. In severe or advanced cases, azotemia may occur, and cases of death from uremia are rarely reported. Acquired renal arteriovenous malformation and compression may coexist with symptoms and signs of the primary disease.

　　Four, large renal arteriovenous fistulas can cause left-to-right shunting in the circulation, increase the preload of the heart, and the decrease in renal blood flow can lead to an increase in blood volume and an increase in arterial pressure, which can further increase the preload and afterload of the heart. Severe cases can cause acute heart failure, which is life-threatening.

　　Five, some patients have mild clinical manifestations or no manifestations at all, leading to a high misdiagnosis rate. Occasionally, it has been reported that varicocele is the only complaint, and the diagnosis is left renal vein compression syndrome.

　　In general, renal vascular malformation and compression can be divided into the following situations: renal artery stenosis and compression malformation, mostly presented with hypertension; renal vein compression, mostly presented with hematuria and proteinuria; small renal arteriovenous fistula, clinical symptoms are often absent, while large fistula openings are the first symptoms of heart failure. Renal artery malformation or compression leading to secondary hypertension has been described in relevant chapters. Here, the clinical manifestations of renal arteriovenous fistula and renal vein compression malformation are discussed in detail. Other renal vascular malformations are rare in clinical practice and often have no clinical symptoms, so detailed descriptions are not made.

　　1, Renal arteriovenous fistula:Renal arteriovenous fistula malformation can be divided into congenital and acquired according to the etiology, into intrarenal and extrarenal types according to the location of the fistula opening, and into varicose type and aneurysmal type according to the clinical symptoms.

　　①Varicose type: mostly congenital renal arteriovenous fistula, with relatively small fistula openings. Clinically, the vast majority of patients are asymptomatic, and a few patients may have lumbar costal pain. When the varicose fistula tract ruptures, hematuria may occur, and the ureter and urethra may cause pain, frequent urination, urgency, and difficulty in urination due to blood clot blockage. Pregnant women may induce congestive heart failure due to a sharp increase in blood volume and an increase in arterial pressure, but it is not common. The fistula openings of this type are mostly located outside the kidney.

　　②Arteriovenous malformation type: mostly acquired, commonly seen in renal surgery, trauma, renal abscess rupture, renal tumor, etc., with a large fistula opening and a short fistula tract, with a large amount of arteriovenous shunting. Clinically, in addition to the manifestations of the primary disease, there are often symptoms and signs of cardiovascular system, mainly the clinical manifestations of congestive heart failure, and may also have lumbar and abdominal vascular murmurs, increased blood pressure, etc. However, the arteriovenous fistula complications of renal puncture biopsy are often very small, the fistula opening can heal spontaneously in 2 weeks to 18 months, and in the absence of severe symptoms, it is generally not necessary to undergo special treatment.

　　2. Left renal vein compression syndrome (LRVES):Since Nutcracker described the left renal vein compression syndrome in 1972, many cases have been reported in China and abroad. The disease is more common in children and young adults, affecting both males and females. The vast majority of patients present with gross hematuria as the initial symptom, and some patients have lumbar pain. There are also reports of patients presenting with orthostatic proteinuria as the only clinical manifestation.

　　2. Follow-up observation: The vast majority of patients with congenital renal vascular malformation or compression do not require treatment if there are no clinical symptoms. However, long-term follow-up observation is necessary, and timely treatment should be sought if there is severe organ dysfunction.

　　1. For renal vascular malformation and compression caused by acquired factors, it is necessary to actively treat the primary disease to relieve compression, improve the condition, and prevent the occurrence of various complications.

　　1. Blood examination:Renal vascular malformation and compression, except for a few patients who may have increased activity of the renin-angiotensin system, almost no other biochemical examination abnormalities are found. Renal function impairment is generally mild, and only in severe or advanced cases may azotemia occur.

　　2. Urinalysis:Hematuria is common, and proteinuria may also occur.

　　The diagnosis of this disease mainly relies on imaging examinations.

　　3. X-ray examination

　　1. Plain film:It may be normal, or in severe cases of renal hypoperfusion, one side of the renal shadow may appear smaller, and patients with left renal vein compression syndrome may have an enlarged left renal shadow.

　　2. Renal venography:Generally, there are no positive findings. In cases where there is organ swelling or compression near the renal hilum, there may be compression and deformation of the renal pelvis with obstruction of contrast medium excretion.

　　3. Renal Arteriography:The renal vascular malformation or compressed areas, the extent, degree, pathological nature, collateral circulation, and details of changes in the abdominal aorta can be directly displayed. Congenital renal arteriovenous fistula is often located near the renal hilum in the central part of the kidney, showing clumps of coiled blood vessels, thickened supplying arteries, early appearance of the renal vein, and even the inferior vena cava may be visualized during the arterial phase. Acquired arteriovenous fistula can be seen with thickened supplying arteries, early appearance of the renal vein, and cystic dilation; during the renal parenchyma phase, the diseased side of the renal parenchyma appears as a conical hypodense area, and patients with left renal vein compression syndrome can undergo abdominal aortic or renal artery angiography to show the location of the angle between the abdominal aorta and the superior mesenteric artery and the position relationship with the left renal vein during the arterial phase, and the degree and location of compression of the left renal vein during the venous phase. The renal parenchyma on the affected side shows a conical hypodense area at the site of the lesion during the renal parenchyma phase. Patients with left renal vein compression syndrome can undergo abdominal aortic or renal artery angiography to show the location of the angle between the abdominal aorta and the superior mesenteric artery and the position relationship with the left renal vein during the arterial phase, and the degree and location of compression of the left renal vein during the venous phase.

　　Four, CT Scan:It can show the shape of the kidney, the nature, location, size, shape, and compression of kidney and perirenal tumors, which is of certain significance for differential diagnosis.

　　Five, Abdominal Ultrasound Examination:Renal color Doppler examination can detect abnormal blood flow, and B-ultrasound can show the size and condition of the kidney and tumors, but the sensitivity is not high.

　　Six, Nuclear Medicine Examination:Radionuclide renal blood pool or renal parenchyma imaging has no specificity for diagnosing renal arteriovenous fistula and renal vascular compression, but it has certain value in differential diagnosis. Additionally, if the 99mTc-RBC blood pool imaging shows local high concentration shadows, while the 99mTc-gluconate calcium renal imaging shows local defects in the same area, it has qualitative significance for diagnosing renal aneurysm.

　　First, Food Therapy Formula

　　1. Sea Cucumber Porridge:50 grams of dried sea cucumber (chopped), 100 grams of glutinous rice, cooked into porridge together, with a little scallion, ginger, and salt for seasoning. It has the effects of tonifying the kidney and enriching essence, nourishing yin and blood. It is suitable for those with kidney yin deficiency, leading to weakness of the physique, weakness of the waist and knees, insomnia, and night sweats.

　　2. Lycium Pork Kidney Porridge:10 grams of Lycium barbarum, one pork kidney (with the inner membrane removed and chopped), 100 grams of glutinous rice, a little scallion, ginger, and salt, cooked into porridge together. It has the effects of nourishing kidney yin and yang, consolidating essence, and strengthening the waist. It is suitable for kidney deficiency and exhaustion, with both yin and yang deficiency, leading to lumbar and spinal pain, weakness of the waist and knees, weakness of the legs and feet, dizziness, and tinnitus. This recipe is a classic in kidney deficiency food therapy.

　　3. Cistanche Sheep Kidney Porridge:10 grams of Cistanche deserticola, one sheep kidney (with the inner membrane removed and chopped), 100 grams of glutinous rice, cooked into porridge together. It has the effects of tonifying the kidney and yang, enriching essence and promoting bowel movements. It is suitable for the elderly with kidney yang deficiency, leading to aversion to cold, coldness of the limbs and waist, frequent urination, nocturnal enuresis, and constipation. This recipe is a classic in kidney deficiency food therapy.

　　4. Deer Antler Glue Porridge:6 grams of deer antler glue, 100 grams of glutinous rice, boil the rice into porridge, then crush the deer antler glue and dissolve it in the hot porridge, add an appropriate amount of sugar. It has the effects of tonifying kidney yang and enriching essence and blood. It is suitable for those with insufficient kidney yang and deficient essence and blood, leading to emaciation, weakness of the waist and knees, pain, seminal emission, and impotence.

　　5. Eucommia Kidney Slices:12 grams of eucommia, boiled and filtered for use. One pair of pork kidneys, with the inner membrane removed, cut into kidney slices. Use the eucommia decoction as the sauce, add scallions, ginger, and salt, and stir-fry until done. It has the effects of tonifying the liver and kidney, strengthening the tendons and bones, and lowering blood pressure. It is suitable for kidney deficiency and lumbar pain due to insufficient liver and kidney in the middle-aged and elderly, as well as dizziness, tinnitus, and hypertension.

　　6. Roasted Walnut Kernels:10 grams of walnuts, roasted and chewed. It has the effects of tonifying the kidney and warming the lung, moistening the intestines and promoting defecation. It is suitable for kidney deficiency with lumbar pain and weakness of the feet, or for those with deficiency cold cough and constipation.

　　7. Three-ingredient Egg Soup:One egg, 9 grams each of lotus seed core, euryale flos, and hawthorn root, with an appropriate amount of sugar. Boil into a medicine decoction and eat the egg and drink the decoction. It is used to treat kidney deficiency.

　　8, Euryale ferox and walnut porridge:30 grams of Euryale ferox, 20 grams of walnuts, 10 dates, and 50 grams of rice. Cooked as porridge for regular consumption. It has the effect of tonifying kidney, regulating breath, and stopping asthma.

　　9, Five-flavor dessert:150 grams of adzuki beans, 10 grams of black sesame, 5 grams of walnuts, 120 grams of sugar, and 125 grams of lard. Made into desserts for consumption. It is mainly used for kidney deficiency.

　　10, Yam meat ball:200 grams of yam, 300 grams of pork, 30 grams of mushrooms, 1 egg white, 500 grams of peanut oil, a little sesame oil, chopped green onions, a little MSG, a little ginger juice, 5 grams of white pepper, 20 grams of cornstarch, and appropriate amount of salt. Mix all the ingredients to make meat balls for side dishes. It is mainly used for kidney deficiency.

　　11, Mutton and glutinous rice porridge:3 to 5 liang of fresh lean mutton, appropriate amount of glutinous rice. Clean the mutton, cut into pieces, and cook with glutinous rice. This formula benefits Qi and blood, supplements deficiency and damage, warms the spleen and stomach, and is suitable for people with insufficient Yang Qi, Qi and blood deficiency, emaciation, epigastric pain due to deficiency, aversion to cold, cold loins and knees, and weakness.

　　12, Mutton soup:500 grams of mutton, appropriate amounts of fine salt, cooking wine, scallions, ginger, and pepper. Cooked meat and soup for consumption. It has the effects of tonifying kidney Yang, benefiting essence and Qi, and warming the loins and knees. It is suitable for patients with kidney deficiency and back pain, cold pain in both knees, weakness, impotence and seminal emission, and cold hands and feet.

　　13, Millet porridge with sparrows:5 sparrow (with internal organs removed and cleaned), 100 grams of millet, scallions, ginger, vegetable oil, salt, and yellow wine. Cooked as porridge for consumption. This formula has the effect of tonifying Yang and benefiting essence. It is suitable for Yang deficiency and emaciation.

　　14, Hawthorn berries and Chinese wolfberry stewed dog meat:15 grams of hawthorn berries, 15 grams of Chinese wolfberry, 500 grams of dog meat, appropriate amounts of fine salt, cooking wine, and Sichuan pepper. Cooked meat and soup for consumption. It has the functions of tonifying kidney and Yang, strengthening tendons and bones, consolidating essence and astringing intestines, and stopping urine and lochia. It is suitable for kidney deficiency, frequent urination, seminal emission, impotence, premature ejaculation, weakness of the feet, and polyuria in the elderly.

　　15, Stewed pigeon with chicken:One pigeon, 200 grams of chicken, 10 grams of cooked green vegetables, chicken soup, fine salt, pepper, and chopped green onions. Cooked meat and soup for consumption. It can nourish the liver and kidneys, benefit the essence and blood, strengthen Yang and treat flaccidity, dispel wind and detoxify. This soup is suitable for people with emaciation, kidney Yang deficiency, diabetes, and women with blood deficiency and amenorrhea.

　　2. Diet

　　Reduce fluid intake and salt intake, and avoid foods rich in potassium such as oranges, tangerines, and various fruits. Low phosphorus diet, such as avoiding crabs, and not eating plant protein-rich foods such as peanuts, soy products, beans, various nuts, soy milk, etc., should be avoided. Increase calorie intake, such as eating more apples, sweet potatoes, yams, etc.

　　1. Treatment

　　The vast majority of patients with congenital renal vascular malformations or compression have no clinical symptoms and do not require treatment. However, once the existence of such diseases is discovered, long-term follow-up observation is necessary, and surgical treatment is still required if severe organ dysfunction occurs.

　　Renal vascular lesions formed after trauma or surgery generally require surgical treatment. Renal arteriovenous fistulas formed after percutaneous renal biopsy usually do not require treatment and the fistula orifices heal spontaneously within 2 to 18 months, with rare cases leading to clinical symptoms. For patients with tumors or lesions in extrarenal organs compressing renal vessels, the primary disease should be treated first, followed by consideration of renal vascular decompression.

　　The treatment methods for left renal vein compression syndrome have not been unified to this day. Why most patients have anatomical changes of left renal vein compression without clinical symptoms, and the same pathological changes only occur in a few patients with severe symptoms have not been explained reasonably. It is generally believed that in cases where the symptoms are severe and medical treatment has not been effective, surgical treatment should be performed.

　　1. Surgical Treatment

　　(1) Indications: ① Heart failure; ② Progressive renal dysfunction; ③ Tumor compression or fistula formation; ④ Severe pain and hematuria; ⑤ Refractory hypertension; ⑥ Renal trauma leading to fistula.

　　(2) Surgical Method:

　　① Nephrectomy: In cases where there is unilateral renal vascular involvement, severe cardiac and renal insufficiency, and the lesion is extensive and it is difficult to perform renal vascular repair surgery, nephrectomy is still a relatively simple and effective method.

　　② Direct visualization renal vascular repair surgery: suitable for patients with renal arteriovenous fistula and renal artery aneurysm. The fistula can be directly eliminated, and the aneurysm and varicose vessels can be excised, but there is a possibility of renal ischemia complications. Before surgery, a detailed understanding of the blood supply of the lesion should be obtained through renal angiography to reduce the occurrence of renal ischemia.

　　2. Interventional Radiological Treatment:That is, at the same time as renal angiography, embolization, dilation, or placement of stents is performed on the diseased vessels through catheters to eliminate the symptoms of fistula, stenosis, or compression. The advantages of this method are minimal damage, good tolerance of patients, only requiring a small amount of local anesthesia, no anesthetic complications, and fast postoperative recovery. This method can be tried for both mild and severe patients. However, this method can also cause complications such as renal ischemia, and there is also a possibility of complications such as embolism or stent detachment, vascular injury, and bleeding during the catheter manipulation process, which should be avoided as much as possible.

　　In summary, renal vascular malformation and compression are a class of complex and diverse diseases. The determination of treatment methods depends not only on clinical symptoms but also on comprehensive consideration of different types of pathological anatomical changes, specific analysis, in order to achieve minimal damage, good results, and reduce mortality.

　　II. Prognosis

　　The prognosis of this disease is related to the degree of vascular malformation and compression. Mild cases show no obvious pathological changes clinically and have a good prognosis. Severe cases can cause multiple systemic lesions such as heart failure, renal vein compression syndrome, severe hypertension, and acute renal failure, at which time the mortality rate is high and the prognosis is poor.