Intrarenal arteriovenous malformation

Recurrent urinary retention due to clots caused by a congenital renal arteriovenous malformation that forms a complex vascular network: Report of two cases

INTRODUCTION

Repeated urinary retention due to clots caused by congenital renal arteriovenous malformation is rare.

CASE PRESENTATION

A 40-year-old woman (case 1) and a 66-year-old man (case 2) experienced recurrent urinary retention due to clots. Neither patient had a history of renal trauma nor was taking any medications. Contrast-enhanced abdominal computed tomography revealed a large hematoma in the renal pelvis and ureter with no masses, stones, or vascular lesions and only dilated blood vessels in the arterial phase in case 1. Angiography of the kidney in both patients revealed an arteriovenous malformation, and embolization of the arteries feeding the arteriovenous malformation was performed. Soon after embolization, hematuria disappeared completely with no recurrence for 5 years in case 1 and 2 years in case 2.

CONCLUSION

Congenital renal arteriovenous malformation should be considered as a cause of recurrent clot retention, and angiographic embolization of the feeding arteries can be an effective treatment.

Endovascular catheter arterial embolization effectively treats secondary hypertension and increased plasma B-type natriuretic peptide level accompanied by idiopathic renal arteriovenous fistula

A 65-year-old woman with a history of hypertension and atrial fibrillation was referred to our hospital following detection of microscopic hematuria.

Physical examination showed continuous vascular murmur with the maximum point on the right side of the umbilicus. Contrast-enhanced computed tomography showed a right renal aneurysmal-type arteriovenous fistula. She underwent endovascular catheter arterial embolization. Following this, her blood pressure was virtually normalized, and her levels of plasma BNP were significantly reduced.

We recommend that patients with microscopic hematuria should be auscultated around the navel, because renal AV shunt is treatable; this may facilitate cure of secondary hypertension and cardiac load.

Transarterial embolisation for congenital renal arteriovenous malformations improves clinical condition even with partial obliteration

AIM

To evaluate the efficacy and safety of transarterial embolisation (TAE), used to treat congenital renal arteriovenous malformations (CRAVMs).

MATERIALS AND METHODS

The medical records were searched retrospectively to identify patients who underwent TAE to treat CRAVM from January 2003 to August 2015. Patient demographics, clinical presentations, and imaging findings were reviewed. TAE outcomes, including complete or partial obliteration, clinical success, complications, renal function changes, and relapse of symptoms or signs after the final TAE, were assessed.

RESULTS

Over the 12-year period, 16 patients (nine male, seven female; median age, 47 years) who underwent 21 TAE procedures to treat 16 CRAVMs were enrolled in the study. The most common clinical presentation was haematuria (81.3%). Thirteen patients (81.3%) had cirsoid and three (18.7%) had aneurysmal CRAVMs. Of the 16 CRAVMs, 11 (68.8%) were peripheral, four (25%) were central, and one (6.3%) was both peripheral and central. The complete obliteration rate was 56.3%. The clinical success rate was 87.5% over a median follow-up period of 398.5 days. Two (9.5%) major complications and 14 (66.7%) minor complications were encountered. No statistically significant change in renal function was evident after TAE.

CONCLUSION

TAE was safe and effective when used to treat CRAVM; the complication profile was acceptable and renal function was preserved. TAE improved the clinical condition of CRAVM patients even when obliteration was only partial.

Extensive Renal Arteriovenous Malformations Treated by Transcatheter Arterial Embolization

An 84-year-old woman was referred to our department due to gross hematuria. Enhanced computed tomography revealed early enhancement of the right renal vein and multiple tortuous vessels around the right renal hilus, part of which had invaded into the renal parenchyma and renal calix. We diagnosed her with arteriovenous malformations (AVMs) and performed transcatheter arterial embolization (TAE). Angiography showed extensive and complex AVMs located in the central and peripheral areas of her kidney. After TAE, the hematuria resolved and she became hemodynamically stable.

Embolization of Congenital Renal Arteriovenous Malformations Using Ethanol and Coil Depending on Angiographic Types

PURPOSE

To evaluate effectiveness and safety of embolization of congenital renal arteriovenous malformations (AVMs) using ethanol and/or coil according to angiographic type.

MATERIALS AND METHODS

Between August 2010 and October 2015, 11 patients (13 sessions; 10 women and 1 man; mean age, 50.8 y) with congenital renal AVMs were treated using ethanol and/or coils via 2 approaches (transarterial access or direct puncture). Demographics, clinical findings, diagnostic modalities, angiographic types, technical and clinical success rates, and complications were reviewed. Renal AVMs were classified into 3 angiographic types, and treatment was based on this classification.

RESULTS

Technical success rate was 91% (10/11), and clinical success rate was 100% (11/11). Of patients, 7 had type III AVMs, 3 had type I AVMs, and 1 had type II AVM. Embolic agents were ethanol in 5 patients, coils with ethanol in 3 patients, and coils in 3 patients. Of the 8 patients treated with ethanol, 6 had infarcted renal areas of 3.5%-30% (mean, 14.6%). After a mean follow-up period of 16.3 months, there was no evidence of recurrent AVMs on imaging or laboratory studies.

CONCLUSIONS

Embolization of congenital renal AVMs via transarterial or direct percutaneous approaches using ethanol and/or coils based on a simple angiographic classification was safe and effective and elicited good outcomes. Most of the patients with congenital renal AVMs were women.

Salvage of bleeding renal allograft following biopsy, with suture technique: a case report

Background

Percutaneous renal biopsy is a valuable procedure in the management of and prognostication for patients with renal disease. Complications, although rare, occur with renal biopsies. Arteriovenous fistulas and heavy bleeding are notable complications. In this report, we describe simple suturing of the biopsy tract for salvage of a graft destined for a nephrectomy due to a profusely bleeding arteriovenous fistula.

Case presentation

A 20-year-old Sri Lankan man with end-stage renal disease due to steroid-resistant nephrotic syndrome underwent a renal transplant. He had poor urine output following the surgery, and a renal biopsy was performed to diagnose his renal pathology. He experienced poorly controlled postprocedural hypertension, and he had four episodes of gross hematuria that required blood transfusion. Coil embolization was delayed due to technical issues, and a graft nephrectomy was planned following the fourth episode of hematuria, which was the most severe. A Doppler scan revealed a slender, iatrogenic arteriovenous fistula corresponding to the biopsy tract, with very high flow rates. With knowledge of the anatomy of the fistula, we performed suturing of the tract to obliterate the fistula as a last resort to salvage the graft. The surgical procedure stopped the bleeding, and the patient made a full recovery with an excellent quality of life.

Conclusions

In our patient, a renal transplant biopsy revealed acute tubular necrosis. The incidence and treatment of fistulas and differences in complication rates among native and graft kidney biopsies are discussed.

Renal Arteriovenous Shunts: Clinical Features, Imaging Appearance, and Transcatheter Embolization Based on Angioarchitecture

Renal arteriovenous (AV) shunt, a rare pathologic condition, is divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain, and high-output heart failure. Although transcatheter embolization is a less-invasive and effective treatment option, it has a potential risk of complications, including renal infarction and pulmonary embolism, and a potential risk of recanalization. The successful embolization of renal AV shunt requires a complete occlusion of the shunted vessel while preventing the migration of embolic materials and preserving normal renal arterial branches, which depends on the selection of adequate techniques and embolic materials for individual cases, based on the etiology and imaging angioarchitecture of the renal AV shunts. A classification of AV malformations in the extremities and body trunk could precisely correspond with the angioarchitecture of the nontraumatic renal AV shunts. The selection of techniques and choice of adequate embolic materials such as coils, vascular plugs, and liquid materials are determined on the basis of cause (eg, traumatic vs nontraumatic), the classification, and some other aspects of the angioarchitecture of renal AV shunts, including the flow and size of the fistulas, multiplicity of the feeders, and endovascular accessibility to the target lesions. Computed tomographic angiography and selective digital subtraction angiography can provide precise information about the angioarchitecture of renal AV shunts before treatment. Color Doppler ultrasonography and time-resolved three-dimensional contrast-enhanced magnetic resonance angiography represent useful tools for screening and follow-up examinations of renal AV shunts after embolization. In this article, the classifications, imaging features, and an endovascular treatment strategy based on the angioarchitecture of renal AV shunts are described.

Renal arteriovenous malformation presenting with massive hematuria

Renal arteriovenous malformations are abnormal communications between the intrarenal arterial and venous systems. They are a rare cause of hematuria. Color Doppler ultrasonography, multislice CT angiography, and DSA are important tools for making the diagnosis. We describe the case of a 62-year-old man with renal arteriovenous malformation who presented with gross hematuria.

Double Coaxial Microcatheter Technique for Glue Embolization of Renal Arteriovenous Malformations

PURPOSE

To demonstrate the technical benefit of the double coaxial microcatheter technique for embolization of renal arteriovenous malformations (AVMs) with n-butyl cyanoacrylate and iodized oil (glue).

MATERIALS AND METHODS

Six consecutive patients (1 man and 5 women; mean age 61 years; range 44-77 years) with renal AVMs were included. Five patients had hematuria, and one had a risk of heart failure due to a large intrarenal arteriovenous shunt. All patients underwent transarterial embolization using glue and the double coaxial microcatheter technique with outer 2.6F and inner 1.9F microcatheters. After glue injection, the inner microcatheter was retracted, while the outer microcatheter was retained. We assessed the complications and clinical outcomes of this technique.

RESULTS

Technical success was achieved in all patients. In 9 sessions, 34 feeding arteries were embolized with glue using the double coaxial microcatheter technique, 1 was embolized with glue using a single microcatheter, and 2 were embolized with coils. The double coaxial microcatheter technique was useful for selecting small tortuous feeding arteries, preventing glue reflux to the proximal arteries, and approaching multiple feeding arteries without complete retraction of the microcatheters. As a minor complication, glue migrated into the venous system in four patients without any sequelae. In all patients, favorable clinical outcomes, including hematuria cessation in five patients and improvement of the large intrarenal arteriovenous shunt in one patient, were obtained without deterioration of renal function.

CONCLUSION

Glue embolization with the double coaxial microcatheter technique was useful for treating renal AVMs with multiple tortuous feeding arteries.

Transarterial embolisation of renal arteriovenous malformation: safety and efficacy in 24 patients with follow-up

AIM

To evaluate the efficacy and safety of renal artery embolisation (RAE) for renal arteriovenous malformation (AVM) as well as its outcomes.

MATERIALS AND METHODS

The technical and clinical success rates, radiological and laboratory findings, and complications of RAE for 31 renal AVMs in 24 patients (M:F=9:15, mean age 46 years) at two separate medical institutions were retrospectively evaluated. Technical success was defined as complete occlusion of feeding arteries with no residual nidus seen on post-treatment angiography. Clinical failure was defined as recurrence of haematuria, presence of AVM on follow-up ultrasound or computed tomography, repeated RAE or surgery for the control of haematuria. Overall clinical success was defined as resolution haematuria or disappearance of AVM on follow-up imaging after single or multiple sessions of RAE.

RESULTS

Types of renal AVM were AVM, arterio-venous fistula (AVF) with intranidal aneurysm, and acquired AVF in 19, 1, and 4 patients, respectively. 18 patients (75%) underwent a single session of RAE, while 6 patients (25%) had two or more sessions of RAE. The level of embolisation was feeder, segmental artery, and main renal artery in 28 (90%), 2 (6%), and 1 (4%) procedures, respectively. Coil, n-butyl 2-cyanoacrylate, and polyvinyl alcohol were the most frequently chosen embolic materials and were used in 19, 14, and 8 procedures, respectively. The clinical success rate after initial RAE was 67% (16/24). Overall clinical success rate, including multisession RAE, was 88% (21/24). The technical success rate of 31 procedures was 65% (20/31). Among 11 technical failures in 10 patients, 4 achieved clinical success without additional RAE, 3 underwent second session RAE to achieve clinical success, and 3 patients underwent nephrectomy due to recurrence.

CONCLUSION

RAE is a safe and effective treatment for renal AVM. Technical failure of RAE does not always lead to clinical failure and multiple embolisation sessions may be effective for recurrent renal AVM.

Aneurysm of the right renal vein arising from an idiopathic arteriovenous fistula

A renal vein aneurysm is rarely secondary to an arteriovenous fistula. A symptomatic 4.7-cm aneurysm of the right renal vein arising from an idiopathic arteriovenous fistula in a 41-year-old woman is described. Imaging techniques have a critical role in planning the treatment. The 4.7-cm aneurysm showed a venous wall with uneven thickening of the intima, irregular atrophy and architectural disarray of the media, and partial loss of elastic fibers. Potential for rupture supports surgical intervention in a selected patient with a macroaneurysm.

Renal arteriovenous fistula revealed by severe hypertension during pregnancy

A 35-year-old woman developed severe hypertension resistant to antihypertensive treatment during the second trimester of pregnancy at 24 weeks gestation. Doppler ultrasonography achieved the diagnosis of idiopathic renal arteriovenous fistula in the left kidney associated with parenchymal hypoperfusion. A Caesarean section was performed 6 days after the diagnosis because of severe pre-eclampsia. After delivery, the symptoms disappeared. Fistula persisted after follow-up for over 1 year but with a dramatic decrease in its blood flow and normalisation of the left kidney hemodynamics. Nevertheless, embolisation was performed without complications to prevent recurrence during the next pregnancy expected by the patient.

Gross hematuria caused by a congenital intrarenal arteriovenous malformation: a case report

Introduction

We report the case of a woman who presented with gross hematuria and was treated with a percutaneous embolization.

Case presentation

A 48-year-old Caucasian woman presented with gross hematuria, left flank pain, and clot retention. The patient had no history of renal trauma, hypertension, urolithiasis, or recent medical intervention with percutaneous instrumentation. The patient did not report any bleeding disorder and was not taking any medication. Her systolic and diastolic blood pressure values were normal at presentation. The patient had anemia (8 mg/dL) and tachycardia (110 bpm). She underwent color and spectral Doppler sonography, multi-slice computed tomography, and angiography of the kidneys, which showed a renal arteriovenous malformation pole on top of the left kidney.

Conclusions

The feeding artery of the arteriovenous malformation was selectively embolized with a microcatheter introduced using a right transfemoral approach. By using this technique, we stopped the bleeding, preserved renal parenchymal function, and relieved the patient's symptoms. The hemodynamic effects associated with the abnormality were also corrected.

Congenital intrarenal arteriovenous malformation presenting with gross hematuria after endoscopic intervention: a case report

Introduction

Although diagnostic ureterorenoscopy is a minimally invasive and effective diagnostic procedure, it has the potential for significant postoperative complications. We report the first case in the literature of intrarenal arteriovenous fistulas causing hemodynamic effective anemia 4 days after ureterorenoscopic biopsy.

Case presentation

A 63-year-old Caucasian woman presented with hemodynamic effective macrohematuria (hemoglobin 70 g/liter) 4 days after ureterorenoscopy and biopsy of the upper pole collecting system due to recurrent microhematuria. Duplex-sonography and computed tomography angiography revealed multiple arteriovenous fistulas and erosions into the calyceal system. Intra-arterial digital subtraction angiography confirmed this condition. After superselective embolization of the arteriovenous fistulas, the patient had no further episodes of bleeding or microhematuria.

Conclusion

If malignancies, urolithiasis or urinary tract infections are ruled out by common diagnostic procedures as the cause of recurrent minor or gross hematuria, the possibility of arteriovenous fistulas should be included in the differential diagnosis and Duplex-Sonography or the more invasive selective renal arteriography should be performed as this is the most definitive method for diagnosing arteriovenous fistula.

[Doppler US of the urinary system and renal vessels in normal and pathologic conditions]

The interest of Doppler ultrasound (US) in urinary tract investigation has dramatically increased during the past 10 years. It can provide useful diagnostic informations in pedicular and intrarenal vascular disorders, some medical nephropathies, in the assessment of renal tumors and urinary tract disorders including urolithiasis, acute obstruction and ureteral reflux. Recent technical improvements including the development of US contrast agents (microbubbles) have contributed to increase the diagnostic accuracy of the technique.

Two giant renal aneurysms and renal arteriovenous fistula associated with cardiac insufficiency and a sustained elevation of atrial natriuretic peptide and brain natriuretic peptide

A 64-year-old man presented with chief complaints of exertional dyspnea and palpitation. He had previously undergone left nephrolithotomies twice. A chest roentgenogram showed pleural effusion on both sides with cardiac dilation, and electrocardiography showed a frequent occurrence of ventricular premature contractions. An echocardiogram showed diffuse hypokinesis of the left ventricular wall motion (ejection fraction, 45%) and dilation of the left ventricle (left ventricular end-diastolic dimension, 61 mm). We administered diuretics, ACE inhibitors and a beta-adrenergic blocking agent after making a diagnosis of cardiac insufficiency. Because coronary angiography showed 90% stenosis of the left anterior descending coronary artery (No. 7), we performed coronary angioplasty in this locus. Though both the left ventricular wall motion and ejection fraction improved, and the clinical symptoms disappeared, the left ventricular end-diastolic dimension, and arrhythmia did not improve. Furthermore, the brain natriuretic peptide increased despite these treatments. Thereafter, a left renal artery aneurysm (extrarenal aneurysm measuring 5 cm in diameter and an intrarenal aneurysm measuring 3 cm in diameter) and a left renal arteriovenous fistula were discovered when abdominal echography was performed because of epigastric discomfort. As a result, a left total nephrectomy was performed. Subsequently, the left ventricular end-diastolic dimension and arrhythmia improved, and the brain natriuretic peptide returned to a normal value. We herein report a case that developed cardiac insufficiency due to a renal aneurysm and renal arteriovenous fistula after undergoing left nephrolithotomies twice.

Radiofrequency ablation of a recanalized renal arteriovenous malformation

Radiofrequency (RF) ablation is becoming established as a method of treatment of small renal neoplasms. Successful RF ablation of a renal arteriovenous malformation (AVM) was performed in a patient who had previously undergone coil embolization and experienced hematuria after the feeding vessels recanalized. The 3.5-cm lesion was successfully treated with RF ablation, resulting in cessation of hematuria. At follow-up, there was no residual enhancement of the AVM on computed tomography and the lesion had decreased in size.

Erosion of embolization coils and guidewires from the kidney to the colon: delayed complication from coil and guidewire occlusion of renal arteriovenous malformation

Percutaneous transarterial embolization is a useful, nondrastic, valuable, and commonly used therapeutic option for the treatment of renal arteriovenous malformation (AVM). Compared with partial or total nephrectomy, transarterial embolization is more conservative and preserves renal function. However, it has some limitations and complications that could cause renal infarction and progression of hypertension, renal insufficiency, and pulmonary embolism. Large-sized AVM and multiplicity of abnormal vessels also limit the use of the embolization technique. The authors experienced erosion of the coils and guidewires that were used for embolization of renal AVM from kidney to descending colon. Coil embolization is practiced extensively, but a complication such as this does not appear to have been described.

Endovascular Treatment of Renal Arteriovenous Malformations

We report a case of renal arteriovenous malformation treated with superselective endovascular embolization using a light mixture of n-butyl-2-cyanoacrylate and Lipiodol. Diagnostic imaging modalities and treatment methods are discussed. In conclusion, successful superselective embolization should be the standard of care.

Congenital bilateral renal arteriovenous malformation: an unrecognized cause of renal failure

Congenital renal arteriovenous malformations (AVM) are very rare abnormal communications between arteries and veins. These lesions are almost always unilateral, predominantly in the right kidney, and usually asymptomatic until adulthood. We present a unique case of bilateral renal AVM in a 10-year-old white boy who developed renal failure requiring renal transplantation. Microscopic sections of an atrophic right and a slightly larger left kidney with tortuous and dilated hilar vessels showed elaborate derangement of arteries and veins insinuating between lobules. Glomeruli were diffusely enlarged with increased number of capillary loops. Glomerular basement membrane reduplication and fibrinoid necrosis was focally noted. Electron microscopy demonstrated absence of electron-dense deposits or mesangial interposition excluding membranoproliferative glomerulonephritis. We believe that the glomerular lesions are secondary to congenital renal arteriovenous malformation. To our knowledge, bilateral arteriovenous malformation in infancy is not previously described.

[Diagnostic imaging of peripheral renal vascular disorders]

Peripheral vascular disorders of the kidney involve the intrarenal branches of the renal vascular tree. It include occlusive (infarction and cortical necrosis) and non-occlusive vascular lesions (acquired arteriovenous fistulas, arteriovenous malformation, false aneurysms and microaneurysms). Initial diagnosis relies on color Doppler US and CT angiography. Angiography plays a therapeutic role. MR imaging provides useful diagnostic information on perfusion disorders especially in patients with renal insufficiency.

The role of renal scintigraphy in renal arteriovenous malformation treated by transcatheter arterial embolization

A 41-year-old woman was hospitalized because of gross hematuria. She was found to have a renal arteriovenous malformation and was treated with transcatheter arterial embolization (TAE). Renal scintigraphy with Tc-99m mercaptoacetyltriglycine was performed before and after TAE. Renal scintigraphy was useful for evaluating renal function in this patient.

Staged endovascular occlusion of giant idiopathic renal arteriovenous fistula with platinum microcoils and silk suture threads

Large symptomatic aneurysmal renal arteriovenous (AV) fistulas usually present with a flank bruit, uncontrolled hypertension, and high-output cardiac failure. Traditionally, these have been treated surgically because of the risk of inadvertent pulmonary embolism with use of embolization techniques. The authors report a case of a giant renal AV fistula successfully treated with staged embolization with use of metallic coils and silk suture. This resulted in a graded reduction in the extreme flow through the fistula, followed by delayed thrombosis and cure of the patient's symptoms.

Usefulness of dynamic renal scintigraphy in a patient with renal arteriovenous fistula treated by transcatheter embolization

Tc-99m-DTPA renal scintigraphy was performed before and after transcatheter coil embolization in a patient with renal arteriovenous fistula (AVF). Before embolization, scintigraphy showed a characteristic accumulation pattern compatible with the hemodynamics of an aneurysmal type of AVF in the vascular phase. After embolization, the effects of treatment, such as a change in the split renal function on the treated-side and the disappearance of the shunt flow through the fistula were evident. It was concluded that dynamic renal scintigraphy was very useful for patients with an aneurysmal type of renal AVF scheduled for transcatheter embolization.

High Output Cardiac Failure

Congestive heart failure describes a syndrome with complex and variable symptoms and signs, including dyspnea, increased fatigability, tachypnea, tachycardia, pulmonary rales, and peripheral edema. Although this syndrome usually is associated with low cardiac output, it may occur in a number of so-called high output states, when the cardiac output is normal or greater than normal. A high output state may occur in chronic severe anemia, large arteriovenous fistula or multiple small arteriovenous shunts as in Paget's bone disease, some forms of severe hepatic or renal disorders, and acutely in septic shock. The syndrome of systemic congestion in a high output state is traditionally referred to as high output heart failure. However, the term is a misnomer because the heart in these conditions is normal, capable of generating very high cardiac output. The underlying problem in high output failure is a decrease in the systemic vascular resistance that threatens the arterial blood pressure and causes activation of neurohormones, resulting in an increase in salt and water retention by the kidney. Many of the high output states are curable conditions, and because they are associated with decreased peripheral vascular resistance, the use of vasodilator therapy for treatment of congestion may aggravate the problem. There are other clinically important issues in high output failure that have received little attention in the current medical literature. This article reviews the available data on high output cardiac failure with particular emphasis on the underlying mechanisms and treatment.

Huge renal arteriovenous malformation mimicking simple parapelvic cyst

The presenting symptoms of renal arteriovenous malformations are usually gross hematuria and hypertension. Herein we present an unusual case of huge renal arteriovenous malformation without these signs, but with ultrasound picture mimicking simple parapelvic cyst. Other imaging test, including Duplex ultrasound, computerized tomography and aortography, demonstrated that vascular lesion. We suggest that Duplex ultrasound should accompany the routine renal ultrasound in order not to miss such cases, especially when the physical examination suggests intra-abdominal vascular lesion or bleeding.

High-output heart failure due to a renal arteriovenous fistula in a pregnant woman with suspected preeclampsia

A 29-year-old nulliparous woman had development of hypertension, proteinuria, and congestive heart failure during the third trimester of her pregnancy. Her symptoms and cardiovascular changes were consistent with congestive heart failure and severe preeclampsia. The underlying pathophysiology was believed to be caused by the high-output state of pregnancy and by the increased peripheral vascular resistance of preeclampsia. The patient underwent an elective cesarean section, but her cardiovascular symptoms did not resolve. Soon after delivery, the patient was found to have an arteriovenous fistula of the right renal artery that caused the high-output cardiac state. Embolization and surgical removal of the arteriovenous fistula resulted in complete resolution of the patient's high-output heart failure. All previously reported cases of renal arteriovenous fistulas and malformations that have occurred during pregnancy are reviewed.

Renal arteriovenous malformation mimicking hydronephrosis

Color and spectral Doppler sonography revealed that a patient believed to have hydronephrosis actually had a renal arteriovenous malformation. Although rare, such a misdiagnosis could have serious implications. In the case described here, there was a coexisting carcinoma of the colon, which required staging and could have led to complications for percutaneous intervention. This case illustrates that color Doppler sonography can be used to establish a diagnosis of arteriovenous malformation.

Cirsoid arteriovenous malformation of kidney presenting as a mass suggestive of malignancy

This paper reports a rare case of cirsoid renal arteriovenous malformation (AVM) that showed radiological characteristics of a renal malignancy. Using only conventional procedures such as computerized tomography, the present case was misdiagnosed as a solid tumor mass and therefore radical nephrectomy was indicated. Angiographic analysis is expected to improve the accuracy of diagnosis of AVM, thus reducing the need to resort to invasive techniques.

Congenital renal arteriovenous malformation in pregnancy presenting with hypertension

Congenital renal arteriovenous malformations (AVMs) are rare, with approximately 50 cases reported in the literature. Typically, they are small (1 to 2 cm) and the majority present with hematuria and symptoms and signs of congestive heart failure. Review of the literature revealed only 4 cases reported in pregnant patients and their presentation was with hematuria and rupture of the AVM. We present a case of a young female patient with a 6 cm congenital renal AVM who was otherwise asymptomatic until her first pregnancy, when she developed and presented with symptoms of hypertension and an abdominal bruit. Her symptoms persisted postpartum. Hematuria and rupture of the AVMs were not part of her clinical course. A partial nephrectomy was curative.

Transcatheter embolization of large idiopathic renal arteriovenous fistula

Renal arteriovenous fistulas are unusual lesions with a variety of clinical manifestations. Congenital and acquired forms have been treated successfully with transcatheter embolization for 2 decades. In the case of large aneurysmal lesions the risk of inadvertent pulmonary embolism has traditionally precluded this approach and necessitated open surgery. However, with refinements in angiographic equipment and technique, such an approach is now feasible and desirable.

Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas

Arteriovenous malformations remain relatively rare clinical lesions. However, with an increasing number of percutaneous renal procedures being performed, their overall incidence can be expected to increase. Congenital arteriovenous malformations usually present with hematuria, while acquired fistulas are more likely to present with hemodynamic changes, such as hypertension, cardiomegaly and congestive heart failure. Arteriography remains the principal method of diagnosis. However, newer imaging modalities such as CT, MRI and color duplex ultrasound may make significant contributions in the evaluation of these abnormalities (fig. 1). Surgery, whether nephrectomy or ligation of feeding vessels, has long been the standard treatment for symptomatic arteriovenous malformations or fistulas. The loss of normal renal parenchyma, migration of occluding agents or recanalization of abnormal vessels has limited the use of embolization as a method of treatment in the past. Recently, newer techniques and agents, such as pharmacoangiography and alcohol, have increased the efficacy of embolization therapy, either as an adjuvant to surgery, definitive therapy or palliation. Although to our knowledge there have been no controlled studies comparing surgical treatment versus embolization, certain recommendations can be made. Because of the decreasing morbidity and increasing efficacy, embolization should be attempted at the time of arteriography as a means of treatment for most arteriovenous malformations and fistulas. However, the choice of surgery, embolization or a combination must be individualized for each patient with regard to overall health, symptoms and manifestations of the fistula or malformation (fig. 2).

Arteriovenous malformation of ureter

Congenital arteriovenous malformations of the genitourinary tract are rare. We report the first case of an arteriovenous malformation of the ureter. The patient presented with recurrent hematuria and left flank pain. Evaluation included an intravenous urogram, cystoscopy, and retrograde pyelography. A pedunculated lesion thought to be a fibroepithelial polyp was seen at the time of ureteroscopy, and the lesion treated by excisional biopsy and fulguration. Pathologic examination demonstrated an arteriovenous malformation. After thirty-month follow-up, the patient remains asymptomatic and free of recurrence.

Spectrum of renal vascular malformation

In summary, renal AVMs are rare. The possibility of these lesions should be raised in cases of hematuria of unknown etiology, prolonged hematuria following trauma or needle biopsy, unexplained congestive heart failure or abdominal/flank bruit, or hypertension after renal trauma. Selective renal arteriography is the study of choice for establishing the diagnosis, the hallmark being demonstration of an abnormal arterial communication with a vein. The goal of management should be maximum preservation of renal parenchyma. Observation with follow-up is indicated for asymptomatic AVMs.

Renal arteriovenous fistula associated with a huge renal vein dilatation

We report a case of an aneurysmal type of renal arteriovenous fistula with a huge spherically dilated renal vein. Although the findings on routine computerized tomography made us strongly suspect renal cell carcinoma associated with a hilar lymph node metastasis, we were able to diagnose the arteriovenous fistula by means of a dynamic computerized tomography scan. On the basis of the roentgenographic findings, partial nephrectomy was performed successfully.

Hemodynamic and plasma renin responses to treatment of a renal arteriovenous malformation

We report a case of a right renal arteriovenous malformation with high output cardiac failure and hypertension which was cured by nephrectomy. Hemodynamic findings pre- and post-operatively are presented. Plasma renin activity (PRA), both from peripheral venous and renal vein samples, was assessed. The fall in PRA associated with nephrectomy lends support to the suggestion that the renin-angiotensin system plays a role in the hypertension in these patients.

Congenital arteriovenous malformation of kidney in pregnancy

Two cases of rupture of an arteriovenous malformation (AVM) of the kidney during pregnancy are reported. The surgical options are presented, and a new classification of arteriovenous malformation is proposed.