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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 state
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.
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.
REPORT OF CASE
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.
Seven cases of renal AV lesions (six malformations and one fistula) have previously been reported during pregnancy.
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.
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.
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,
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,
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.
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.
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.
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 fistulas
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.
We thank Dr. James P. Knochel for his critical review of our submitted manuscript.
Maternal cardiovascular dynamics. IV. The influence of gestational age on the maternal cardiovascular response to posture and exercise.