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High-Output Heart Failure Due to a Renal Arteriovenous Fistula in a Pregnant Woman With Suspected Preeclampsia

1998; Elsevier BV; Volume: 73; Issue: 9 Linguagem: Inglês

10.4065/73.9.888

1942-5546

Tommy S. Korn, Jeffrey M. Thurston, Cynthia S. Sherry, Darryl L. Kawalsky,

Abdominal vascular conditions and treatments

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 highoutput 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 highoutput heart failure. All previously reported cases of renal arteriovenous fistulas and malformations that have occurred during pregnancy are reviewed. 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 highoutput 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 highoutput heart failure. All previously reported cases of renal arteriovenous fistulas and malformations that have occurred during pregnancy are reviewed. Arteriovenous (AV) fistulas and AV malformations are rare clinical entities that may cause high-output heart failure. Prompt diagnosis often leads to resolution of the cardiovascular symptoms of heart failure. The presence of an AV fistula or malformation during pregnancy not only contributes to the preexisting high-output cardiac state1Ueland K Novy MJ Peterson EN Metcalfe J Maternal cardiovascular dynamics. IV. The influence of gestational age on the maternal cardiovascular response to posture and exercise.Am J Obstet Gynecot. 1969; 104: 856-864PubMed Scopus (271) Google Scholar, 2Marin-Neto JA Maciel BC Urbanetz LL Gallo Jr, L Almeida-Filho OC Amorim DS High output failure in patients with peripartum car-diomyopathy; a comparative study with dilated cardiomyopathy.Am Heart J. 1991; 121: 134-140Abstract Full Text PDF PubMed Scopus (24) Google Scholar but also may lead to congestive heart failure.3Periman HC Weiland PO An unusual case of arteriovenous fistula diagnosed by arteriography during pregnancy.Angiology. 1973; 24: 212-215Crossref PubMed Scopus (4) Google Scholar, 4Elliott JA Rankln RN Inwood MJ Milne JK An arteriovenous malformation in pregnancy: a case report and review of the literature.Am J Obstet Gynecol. 1985; 152: 85-88Abstract Full Text PDF PubMed Scopus (31) Google Scholar, 5Swinburne AJ Fedullo AJ Gangemi R Mijangos JA Hereditary telangiectasia and multiple pulmonary arteriovenous fistulas: clinical deterioration during pregnancy.Chest. 1986; 89: 459-460Crossref PubMed Scopus (51) Google Scholar Renal AV fistulas and malformations are even rarer clinical entities. The first case was described by Varela6Varela M Aneurisma arteriovenoso de los vasos renales y asistolia consecutiva.Rev Med Lat Am. 1928; 14: 3244Google Scholar in 1928. More than 200 cases of renal AV fistulas and malformations have been reported, but only 7 have occurred during pregnancy.7Smith Jr, GH Remmers Jr, AR Dickey BM Sarles HE Intra renal arteriovenous fistula and systemic hypertension following percutaneous renal biopsy: report of a case.Nephron. 1968; 5: 24-30Crossref PubMed Google Scholar, 8Klimberg I Wilson J Davis K Finlayson B Hemorrhage from congenital renal arteriovenous malformation in pregnancy.Urology. 1984; 23: 381-384Abstract Full Text PDF PubMed Scopus (17) Google Scholar, 9MacMillan RD Robinette MA Congenital arteriovenous malformation of kidney in pregnancy.Urology. 1985; 26: 441-445Abstract Full Text PDF PubMed Scopus (10) Google Scholar, 10Kerr PG Sheridan WP Kelly W Myers K Johnston Cl Hernodynamic and plasma renin responses to treatment of a renal arteriovenous malformation.Aust N ZJ Med. 1986; 16: 1-4Crossref PubMed Scopus (4) Google Scholar, 11Motta J Breslin DS Vogel F Muecke EC Fracchia JA Congenital renal arteriovenous malformation in pregnancy presenting with hyper tension.Urology. 1994; 44: 911-914Abstract Full Text PDF PubMed Scopus (12) Google Scholar, 12Gopalakrishnan G al-Awadi K Bhatia V Mahmoud AH Renal arteriovenous malformation presenting as haematuria in pregnancy.Br J Urol. 1995; 75: 110-111Crossref PubMed Scopus (9) Google Scholar Such vascular lesions can complicate pregnancy. Hypertensive disorders can also complicate pregnancy and are responsible for a substantial number of maternal deaths in the United States13Berg CJ Atrash HK Koonin LM Tucker M Pregnancy-related mortality in the United States. 1987 1990.Obstet Gynecol. 1996; 88: 161-167Crossref PubMed Scopus (393) Google Scholar and worldwide.14Duley L Maternal mortality associated with hypertensive disorders of pregnancy in Africa, Asia. Latin America and the Caribbean.Br J Obstet Gynaecol. 1992; 99: 547-553Crossref PubMed Scopus (399) Google Scholar Patients with pregnancy-induced hypertension (PIH) may have preeclampsia manifested as proteinuria and edema. Only prompt termination of the pregnancy can prevent maternal death due to PIH. In addition, pregnancy can produce a peripartum cardiomyopathy that leads to high-output heart failure.2Marin-Neto JA Maciel BC Urbanetz LL Gallo Jr, L Almeida-Filho OC Amorim DS High output failure in patients with peripartum car-diomyopathy; a comparative study with dilated cardiomyopathy.Am Heart J. 1991; 121: 134-140Abstract Full Text PDF PubMed Scopus (24) Google Scholar If the heart failure and hypertension do not resolve after termination of the pregnancy, an extensive search for other causes is warranted. We describe a 29-year-old woman who had hypertension, proteinuria, and high-output congestive heart failure during the third trimester of her first pregnancy. The patient's cardiovascular symptoms did not resolve after termination of the pregnancy by cesarean section. Subsequently, an AV fistula of the right kidney was detected. A 29-year-old nulliparous woman came to the emergency department during her 28th week of pregnancy because of increasing dyspnea of 2 weeks' duration. She had orthopnea, paroxysmal nocturnal dyspnea, and bilateral pedal edema. She denied having headache, visual disturbances, abdominal pain, or a history of cardiac or hypertensive disease. No history of trauma, renal biopsy, or abdominal operation was noted. She had been monitored closely by her obstetrician for prenatal care and had been noted to be in good health before this assessment. Physical examination showed a resting tachycardia of 100 beats/min and an increased blood pressure of 200/110 mm Hg. Cardiac examination demonstrated jugular venous distention, accentuated first and second heart sounds, a third heart sound in the left lower sternal border, and a grade 3 (on the basis of 1 to 6) systolic ejection murmur heard maximally in the aortic area. Bilateral inspiratory rates were detected in the lung bases. Pedal edema was 4+. Uterine fundal height was 28 cm. The fetal heart tones were normal. Results of laboratory studies revealed a serum albumin level 2.4 of g/dL., a serum total protein value of 5.2 g/dL., and a serum creatinine level of 0.9 mg/dL. (A baseline serum albumin was not available for comparison.) Urinalysis showed 2+ proteinuria. (A 24-hour urine collection was not obtained.) Serum electrolytes, liver function tests, coagulation studies, thyroid function tests, and complete blood cell count were normal. Chest roentgenography demonstrated bilateral pulmonary infiltrates and pleural effusions. An electrocardiogram revealed sinus tachycardia. Transthoracic echocardiography showed normal left ventricular function with no valvular disease. A subsequent ventilation-perfusion scan showed low probability for pulmonary emboli. A Swan-Ganz catheter revealed a cardiac output of 17.2 L./min, cardiac index of 8.7 L/min per m2, pulmonary artery pressure of 40/20 mm Hg, and pulmonary capillary wedge pressure of 20 mm Hg. On admission, the diagnoses were high-output congestive heart failure due to the peripartum state and PIH with features of severe preeclampsia. The patient was given intramuscular magnesium sulfate therapy for seizure prophylaxis and intravenous betamethasone therapy to help fetal maturity. Her blood pressure decreased to 160/100 mm Hg after hydralazine and furosemide were administered. Diuretic treatment resulted in excretion of 6 L of urine. Despite 2 days of intensive medical therapy, hypertension and congestive heart failure persisted. An elective cesarean section was performed. The viable male neonate weighted 1.6 kg and had Apgar scores of 8 and 9 at 1 and 5 minutes, respectively. The umbilical cord blood gas analysis revealed a pH of 7.43, partial pressure of carbon dioxide of 37 mm Hg, partial pressure of oxygen of 58 mm Hg, and base excess of +1. Findings on pathologic examination of the placenta were normal. The condition of the patient and the infant was stable postoperatively. High-output congestive heart failure persisted without change. A continuous bruit was detected posteriorly near the base of the right lung that had not been appreciated before delivery of the newborn. Contrast-enhanced spiral computed tomography showed asymmetry of nephrograms with delayed opacification on the right; tortuous large-caliber vessels filled the right renal pelvis (Fig. 1). The findings were consistent with either an AV fistula or a vascular malformation of the right kidney. The left kidney was normal. An arteriogram revealed aneurysmal enlargement of the right renal artery and early opacification of the right renal vein, consistent with rapid AV shunting (Fig. 2). The fistula was embolized with Gianturco steel coils until flow to the right renal artery was obliterated. Within 2 days, the patient's cardiovascular symptoms cleared, and her blood pressure (140/70 mm Hg) and hemodynamic factors became normal. The serum creatinine level was 1.1 mg/dL 2 days after embolization of the fistula. Two weeks later, the patient underwent right nephrectomy. Gross examination revealed a 250-g distorted kidney (10 by 9 by 5.5 cm) with a small amount of attached perirenal fat. The specimen was bivalved to reveal an aneurysm (5 by 5 by 4.5 cm) that communicated with the renal artery (Fig. 3). Microscopic examination revealed a dilated renal artery surrounded peripherally by small capillary proliferation. The gross and microscopic findings were consistent with those of an AV fistula of the right kidney. Three months later, both the patient and her baby were healthy.Fig. 2Subtraction image from aortogram, showing pooling of contrast medium in giant vascular channels, resulting in early filling of distended inferior vena cava (IVC), compatible with arteriovenous shunting. Enlarged tributaries extend radially. Pressure within IVC equaled that within aorta. Selective catheterization of renal vein resulted in repeated deflection of catheter back into IVC because of marked turbulence of flow. IVC was dilated with a diameter 3 times larger than diameter of aorta. AC = aortic catheter; AVF = arteriovenous fistula.View Large Image Figure ViewerDownload (PPT)Fig. 3Gross specimen of 250-g distorted kidney, 10 by 9 by 5.5 cm, with small amount of attached perirenal fat. Specimen is bivalved to reveal aneurysm, 5 by 5 by 4.5 cm, that appeared to communicate with renal artery.(Photograph courtesy of Dr. Beverly A. Dickson.)View Large Image Figure ViewerDownload (PPT) Seven cases of renal AV lesions (six malformations and one fistula) have previously been reported during pregnancy.7Smith Jr, GH Remmers Jr, AR Dickey BM Sarles HE Intra renal arteriovenous fistula and systemic hypertension following percutaneous renal biopsy: report of a case.Nephron. 1968; 5: 24-30Crossref PubMed Google Scholar, 8Klimberg I Wilson J Davis K Finlayson B Hemorrhage from congenital renal arteriovenous malformation in pregnancy.Urology. 1984; 23: 381-384Abstract Full Text PDF PubMed Scopus (17) Google Scholar, 9MacMillan RD Robinette MA Congenital arteriovenous malformation of kidney in pregnancy.Urology. 1985; 26: 441-445Abstract Full Text PDF PubMed Scopus (10) Google Scholar, 10Kerr PG Sheridan WP Kelly W Myers K Johnston Cl Hernodynamic and plasma renin responses to treatment of a renal arteriovenous malformation.Aust N ZJ Med. 1986; 16: 1-4Crossref PubMed Scopus (4) Google Scholar, 11Motta J Breslin DS Vogel F Muecke EC Fracchia JA Congenital renal arteriovenous malformation in pregnancy presenting with hyper tension.Urology. 1994; 44: 911-914Abstract Full Text PDF PubMed Scopus (12) Google Scholar, 12Gopalakrishnan G al-Awadi K Bhatia V Mahmoud AH Renal arteriovenous malformation presenting as haematuria in pregnancy.Br J Urol. 1995; 75: 110-111Crossref PubMed Scopus (9) Google Scholar Our case is the second renal AV fistula to be reported during pregnancy. The first reported renal AV fistula was the result of a percutaneous renal biopsy performed during the third trimester.7Smith Jr, GH Remmers Jr, AR Dickey BM Sarles HE Intra renal arteriovenous fistula and systemic hypertension following percutaneous renal biopsy: report of a case.Nephron. 1968; 5: 24-30Crossref PubMed Google Scholar Our patient, however, had no history of a renal biopsy. The large size of our patient's fistula and the absence of symptoms until her pregnancy suggested that a small renal AV fistula had been present for many years and had become clinically significant because of the pregnancy. Indeed, investigators have speculated that pregnancy promotes the development of AV lesions.4Elliott JA Rankln RN Inwood MJ Milne JK An arteriovenous malformation in pregnancy: a case report and review of the literature.Am J Obstet Gynecol. 1985; 152: 85-88Abstract Full Text PDF PubMed Scopus (31) Google Scholar Maternal cardiac output typic all y increases between the 20th and 24th week of pregnancy.1Ueland K Novy MJ Peterson EN Metcalfe J Maternal cardiovascular dynamics. IV. The influence of gestational age on the maternal cardiovascular response to posture and exercise.Am J Obstet Gynecot. 1969; 104: 856-864PubMed Scopus (271) Google Scholar Because cardiac output and blood volume increase by at least 50% during pregnancy, investigators have hypothesized that this excess blood volume when shunted through a renal AV lesion results in high-output heart failure in a previously asymptomatic patient.2Marin-Neto JA Maciel BC Urbanetz LL Gallo Jr, L Almeida-Filho OC Amorim DS High output failure in patients with peripartum car-diomyopathy; a comparative study with dilated cardiomyopathy.Am Heart J. 1991; 121: 134-140Abstract Full Text PDF PubMed Scopus (24) Google Scholar, 11Motta J Breslin DS Vogel F Muecke EC Fracchia JA Congenital renal arteriovenous malformation in pregnancy presenting with hyper tension.Urology. 1994; 44: 911-914Abstract Full Text PDF PubMed Scopus (12) Google Scholar Of the seven previously reported cases of renal AV lesions, four (malformations) occurred during the first trimester, and three (two malformations and one fistula) occurred during the third trimester. On the basis of the published literature, the distinction between AV fistulas and AV malformations is confusing because of the different terms used. Each entity has a different cause and clinical manifestation. According to Crotty and associates,15Crotty KL Orihuela E Warren MM Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas.J Urol. 1993; 150: 1355-1359PubMed Google Scholar AV fistulas are acquired anomalous connections between arterial and venous systems that can result from blunt and penetrating trauma, malignant disease, inflammation, and various invasive procedures such as partial nephrectomies, nephrolithotomies,16Lalude AO Martin DC Renal arteriovenous fistula: a complication of anatrophic nephrolithotomy.J Urol. 1983; 130: 754-756PubMed Google Scholar renal artery angioplasties,17Oleaga JA Grossman RA McLean GK Rosen RJ Freiman DB Ring EJ Arteriovenous fistula of a segmental renal artery branch as a complication of percutaneous angioplasty.AJR Am J Roentgenol. 1981; 136: 988-989Crossref PubMed Scopus (14) Google Scholar and percutaneous renal operations18Lee WJ Smith AD Cubelli V Badlani GH Lewin B Vernace F et al.Complications of percutaneous nephrolithotomy.AJR Am J Roentgenol. 1987; 148: 177-180Crossref PubMed Scopus (233) Google Scholar, 19Segura JW Patterson DE LeRoy AJ Williams Jr, HJ Barrett DM Benson Jr, RC et al.Percutaneous removal of kidney stones: review Of 1.000 cases.J Urol. 1985; 134: 1077-1081PubMed Google Scholar and biopsies.20Ekelund L Llndholm T Arteriovenous fistulae following percutaneous renal biopsy.Acta Radiol. 1971; 11: 38-48Crossref Scopus (64) Google Scholar In contrast, AV malformations have multiple communications between the main or segmental renal arteries and veins. Idiopathic AV fistulas constitute less than 3% of all renal AV fistulas.21Stanley JC Rhodes EL Gewertz BL Chang CY Walter JF Fry WJ Renal artery aneurysms: significance of macroaneurysms exclusive of dissections and fibrodysplastic mural dilations.Arch Surg. 1975; 110: 1327-1333Crossref PubMed Scopus (164) Google Scholar The pathophysiology of idiopathic AV fistulas is postulated to be the result of a preexisting renal artery aneurysm eroding into an adjacent vein.22Imray TJ Cohen AJ Hahn L Renal arteriovenous fistula associated with fibromuscular dysplasia.Urology. 1984; 23: 378-380Abstract Full Text PDF PubMed Scopus (22) Google Scholar Various rare AV fistulas and malformations have been described during pregnancy, including cutaneous hemangiomas.23Rose T The hemangiomata of pregnancy.Br J Obstet Gynaecol. 1949; 56: 364-366Crossref Scopus (4) Google Scholar, 24Letterman G Schurter M Barter RH Martin SS Hemangiomas of pregnancy.South Med J. 1957; 50: 594-599Crossref PubMed Scopus (10) Google Scholar pelvic25Benson RC Dotter CT Peterson CG Brlstow JD Metcalfe J Kraushaar OF Congenital arteriovenous fistula and pregnancy.Am J Obstet Gynecol. 1965; 92: 672-683PubMed Scopus (11) Google Scholar and spina26Fields WS Jones JR Spinal epidural hemangioma in pregnancy.Neurology. 1957; 7: 825-828Crossref PubMed Google Scholar, 27Newquist RE Mayfield FH Spinal angioma presenting during pregnancy.J Neurosurg. 1960; 17: 541-545Crossref PubMed Scopus (17) Google Scholar malformations, cerebral malformations and fistulas,28Raskind R Johnson N Hance D Carotid cavernous fistula in pregnancy.Angiology. 1977; 28: 671-676Crossref PubMed Scopus (12) Google Scholar and pulmonary5Swinburne AJ Fedullo AJ Gangemi R Mijangos JA Hereditary telangiectasia and multiple pulmonary arteriovenous fistulas: clinical deterioration during pregnancy.Chest. 1986; 89: 459-460Crossref PubMed Scopus (51) Google Scholar and hepatic29Livneh A Langevitz P Morag B Catania A Pras M Functionally reversible hepatic arteriovenous fistulas during pregnancy in patients with hereditary hemorrhagic telangiectasia.South Med J. 1988; 81: 1047-1049Crossref PubMed Scopus (38) Google Scholar fistulas. A hypothesis is that pregnancy promotes the development of new vascular lesions and enhances the growth of preexisting lesions.4Elliott JA Rankln RN Inwood MJ Milne JK An arteriovenous malformation in pregnancy: a case report and review of the literature.Am J Obstet Gynecol. 1985; 152: 85-88Abstract Full Text PDF PubMed Scopus (31) Google Scholar Typically, the clinical manifestations of renal AV malformations and AV fistulas differ. Congenital renal AV malformations cause hematuria in 72% of reported cases.30Takaha M Matsumoto A Ochi K Takeuchi M Takemoto M Sonoda T Intrarenal arteriovenous malformation.J Urol. 1980; 124: 315-318PubMed Google Scholar Ruptured AV malformations may manifest with urinary retention.9MacMillan RD Robinette MA Congenital arteriovenous malformation of kidney in pregnancy.Urology. 1985; 26: 441-445Abstract Full Text PDF PubMed Scopus (10) Google Scholar, 31Chivate JG Blewitt RW Congenital renal arteriovenous fistula.Br J Urol. 1993; 71: 358-359Crossref PubMed Scopus (5) Google Scholar Renal AV fistulas have manifested with heart failure in 32 to 42% of reported cases and diastolic and systolic hypertension in about 50 to 60% of reported cases.30Takaha M Matsumoto A Ochi K Takeuchi M Takemoto M Sonoda T Intrarenal arteriovenous malformation.J Urol. 1980; 124: 315-318PubMed Google Scholar, 32McAlhany Jr, JC Black Jr, HC Hanback Jr, LD Yarbrough III, DR Renal arteriovenous fistula as a cause of hypertension.Am J Surg. 1971; 122: 117-120Abstract Full Text PDF PubMed Scopus (73) Google Scholar Renal arteriography remains the "gold standard" to identify renal AV fistulas and malformations. The visualization of contrast dye in the inferior vena cava within seconds after injection confirms the presence of a renal AV fistula or malformation. Duplex ultrasonography with color flow Doppler imaging is preferred in a pregnant patient because it is noninvasive and involves no irradiation. On Doppler ultrasonography, turbulent vascular flow echoes within the lesion indicate the presence of an AV fistula or malformation.33Katske F McDonald D Seventy-eight-year old woman with hematuria, hypertension, and flank bruits.Urology. 1991; 38: 582-584Abstract Full Text PDF PubMed Scopus (4) Google Scholar Other noninvasive methods to diagnose AV fistulas and malformations include computed tomography30Takaha M Matsumoto A Ochi K Takeuchi M Takemoto M Sonoda T Intrarenal arteriovenous malformation.J Urol. 1980; 124: 315-318PubMed Google Scholar, 34Honda H Onitsuka H Naitou S Hasuo K Kamoi I Hanada K et al.Renal arteriovenous malformations: CT features.J Comout Assist Tomogr. 1991; 15: 261-264Crossref PubMed Scopus (32) Google Scholar and magnetic resonance imaging.35Selli C Bartolozzi C Lizzadro G Petacchi D Arteriovenous fistula associated with renal cell carcinoma: demonstration by magnetic resonance imaging.Urol Radiol. 1986; 8: 190-193Crossref PubMed Scopus (9) Google Scholar Renal arteriography is the only imaging modality, however, that allows concurrent access for diagnosis and radiographic treatment. Treatment is primarily radiographic embolization and surgical removal of the lesion. Radiographic embolization is achieved through the use of steel Coils36Gianturco C Anderson JH Wallace S Mechanical devices for arterial occlusion.AJR Am J Roentgenol. 1975; 124: 428-435Crossref Scopus (326) Google Scholar, 37Wallace S Gianturco C Anderson JH Goldstein HM Davis LJ Bree RL Therapeutic vascular occlusion utilizing steel coil technique: clinical applications.AJR Am J Roentgenol. 1976; 127: 381-387Crossref PubMed Scopus (141) Google Scholar or silicone polymer injections.38Doppman JL Zapol W Pierce J Transcatheter embolization with a silicone rubber preparation: experimental observations.Invest Radiol. 1971; 6: 304-309Crossref PubMed Scopus (40) Google Scholar Partial or total nephrectomy is the therapy of choice for large aneurysmal AV fistulas and malformations.30Takaha M Matsumoto A Ochi K Takeuchi M Takemoto M Sonoda T Intrarenal arteriovenous malformation.J Urol. 1980; 124: 315-318PubMed Google Scholar Surgical removal results in resolution of hypertension in 62% of all cases of congenital AV malformations and in 85% of all cases of posttraumatic AV fistulas.32McAlhany Jr, JC Black Jr, HC Hanback Jr, LD Yarbrough III, DR Renal arteriovenous fistula as a cause of hypertension.Am J Surg. 1971; 122: 117-120Abstract Full Text PDF PubMed Scopus (73) Google Scholar Because of our patient's cesarean section, we used radiographic embolization of the renal AV fistula instead of the more invasive total nephrectomy. The embolization of the fistula resolved her cardiovascular symptoms. A total nephrectomy was performed at a later date to prevent recurrence of symptoms and to remove a potentially necrotic kidney. Only the removal of the renal AV fistula led to complete resolution of our patient's cardiovascular symptoms. This case was challenging and unique because her hypertension, pathologic edema, and proteinuria led us to believe that preeclampsia was the primary cause of her symptoms. Thus, delivery should have been curative. The patient's symptoms had elements consistent with diagnoses of both preeclampsia and renal AV fistula, such that the former may have been superimposed on the latter. The other feature supporting the coexistence of preeclampsia was proteinuria, a nonspecific sign. Many investigators believe that the diagnosis of preeclampsia is suspect if proteinuria is absent.39Chesley LC Diagnosis of preeelampsia.Obstet Gynecol. 1985; 65: 423-425PubMed Google Scholar The accepted value for proteinuria in preeclampsia is greater than 300 mg of protein per 24 hours or 100 mg/dL of protein in at least two random urine samples. A more definitive diagnosis of severe preeclampsia could have been made in our patient if a 24-hour urine collection for proteinuria had been obtained. The distinction between preeclampsia and renal AV fistula might have been better elucidated if proteinuria had been assessed before and after embolization. If the renal AV fistula had induced changes in glomerular filtration, the proteinuria would have persisted after delivery and would have resolved only after embolization. If preeclampsia was also present, the proteinuria should have eventually resolved after delivery as long as the renal AV fistula did not affect protein filtration. The seven previously reported cases of renal AV fistulas and malformations during pregnancy did not comment on proteinuria as a component of the patient's condition. In one reported case, however, gross proteinuria associated with a renal AV fistula in a nonpregnant patient resolved after nephrectomy.40Kajbafzadeh AM Broumand B Arteriovenous fistula following nephrectomy.Eur Urol. 1997; 31: 112-114PubMed Google Scholar Thus, on the basis of proteinuria, it is difficult to ascertain whether preeclampsia was present in our patient. The most important diagnostic clue was obtained from the abdominal examination, not the urinalysis. Investigators have reported that a continuous, loud abdominal bruit was detected in 74 to 82% of cases of renal AV fistulas30Takaha M Matsumoto A Ochi K Takeuchi M Takemoto M Sonoda T Intrarenal arteriovenous malformation.J Urol. 1980; 124: 315-318PubMed Google Scholar, 32McAlhany Jr, JC Black Jr, HC Hanback Jr, LD Yarbrough III, DR Renal arteriovenous fistula as a cause of hypertension.Am J Surg. 1971; 122: 117-120Abstract Full Text PDF PubMed Scopus (73) Google Scholar and in 9% of cases of renal AV malformations.30Takaha M Matsumoto A Ochi K Takeuchi M Takemoto M Sonoda T Intrarenal arteriovenous malformation.J Urol. 1980; 124: 315-318PubMed Google Scholar In our patient, an abdominal or flank bruit was not detected on initial examination and was discovered only after the delivery of the fetus. This finding resulted in appropriate management of the patient. Although we did not initially suspect the existence of a renal AV fistula, the possibility of severe preeclampsia necessitated immediate medical stabilization. The termination of the pregnancy by cesarean section was necessary in order to halt the life-threatening progression of the disease process. AV fistulas and malformations of the kidney rare clinical entities. Congenital renal AV malformations may manifest with hematuria during pregnancy. Renal AV fistulas, however, often manifest as symptoms of congestive heart failure. Thus, any pregnant patient who initially has hypertension, congestive heart failure, and edema should not necessarily be assumed to have PIH. If these cardiovascular symptoms fail to resolve after termination of the pregnancy, a thorough search should be performed for other causes. A prior history of a renal operation, biopsy, or trauma places the patient at risk for the development of a renal AV fistula. The presence of a renal AV lesion should be considered if a continuous abdominal or flank bruit is detected. Prompt diagnosis and removal of the lesion will lead to resolution of the high-output heart failure and hypertension.