Postnephrectomy arteriovenous fistula

The development of the postnephrectomy arteriovenous fistula (PNAVF) between the renal vessels stumps is rare. Here we present a case report of PNAVF, and review the diagnasis, treatment and preventian. The mast camman clinicai features include a laud murmur aver the previaus nephrectamy scar, and heart failure resistant ta camman medicai treatment. A 58-year-ald white waman was admitted ta the haspital far a camplete evaluatian af an unexplained cangestive heart failure with na respanse ta camman medicai treatment. She had had a right nephrectamy far pyanephrasis 13 years befare. The diagnasis af PNAVF was sL!spected because aver the right lumbar regian a definite trill was palpated, and an auscultatian a harsh, machinery-like murmur was heard. The diagnasis was canfirmed by aartagram and selective renal arteriagraphy. In May 1989, the right arteriavenaus was excised thraugh a right subcastal transperitaneal appraach. The renal vessel stumps were individually Iigated and sutured separately clase ta aarta and vena cava. The patient's pastaperative caurse was entirely uneventful in the fallawing seven years. We canclude that during nephrectamy, the renal vessels shauld be Iigated separately, and the transfixatian in mass af the stumps avaided ta prevent arteriavenaus fistula.


INTRODUCTION
T he development of the postnephrectomy arteriovenous fistula (PNAVF) is arare complication of a common surgical procedure.I -3  Mass ligation and transfixation of the renal vessels in nephrectomy, although commonly practiced, is condemned by many surgeons as favoring the development of arteriovenous fistula.I ,4,5  We present a case of the postnephrectomy arteriovenous fistula, review the literature and discuss the diagnosis, treatment and prevention.

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José Carlos Costa Baptista-Silva Rua Prof. Artur Ramos, 178, 123-Vega São Paulo /SP -Brasil-CEP 01454-904 CASE REPORT R.S., a 58-year-old white woman, was admitted to the Beneficência Portuguesa Hospital with an unexplained congestive heart failure nonresponsive to common medicaI treatment.The patient had undergone a right nephrectomy 13 years earlier for pyelonephrosis, and had been presenting symptoms of gallbladder lithiasis with surgical indication.
Upon physical examination, blood pressure was 150/ 80. mmHg and the cardiac rate was 96 bpm.A trill was palpated over the right lumbar region and a loud, continuous machinery-like murmur was heard upon auscultation over the right flank.Eletrocardiography revealed left ventricular hypertrophy and arrhythmia, and chest roentgenograms showed a minimal cardiomegaly and slight vascular congestiono Alllaboratory tests were within normallimits.
With a suspicion of a systemic arteriovenous fistula, a percutaneous transfemoral abdominal aortogram and a selective renal arteriography were peiformed.Arteriographic studies revealed a dilated right renal artery with a diameter of 10 mm.At a point 3 em from its aortic origin, the contrast medium coursed throúgh a winding channel and entered the inferior vena cava, and a large arteriovenous fistula between the renal artery and vena cava at the site of previous right nephrectomy was revealed.The i lferior vena cava proximal to the renal vessels stumps was dilated and had a maximum diameter about 40 mm (Fig. 1).
On May 3,1989, correction ofthe fistula was carried out through a right subcostal transperitoneal incision.A pulsating mass about 2 em in diameter was found near the right renal vessel stumps.The renal vessel stumps were isolated, ligated and divided.The sac (fistula) was individualized and removed.The renal artery and vein stumps were individually ligated with 2-0 silk, and ~utured separately with monofilamentar polypropylene close to aorta and vena cava respectively.The retroperitoneum was closed, and the cholecystectomy was carried out.
The patient's postoperative course was entirely uneventful.The murmur and trill disappeared after the procedure.The patient was discharged from the hospital five days later on May 8 without any complications.In March 1996, the patient was asymptomatic and clinicaI examinations revealed no sign of heart failure.Blood pressures, analytic tests and pulse were within normal limits, and the cardiomegaly was reduced.An abdominal ultrasonography was within normallimits, except for the absence of the gallbladder, right ki~ney and arteriovenous fistula (postoperative status).

DISCUSSION
Renal arteriovenous fistula can be idiopathic, congenital or acquired A , 6 Postnephrectomy renal arteriovenous fistulas are rare complications that may develop over a period of time ranging from days to 35 years. 2 ,7,8 In 800 renal transplants performed at the University of Minnesota, this complication has occurred only twice, and may well have been caused by simultaneous ligation of renal artery and renal vein. 7 Factors considered to be of etiologic significance in the development of postnephrectomy arteriovenous fistula include: mass ligation of the renal pedicle, especially when transfixation sutures are used; nephrectomy for tuberculosis of the kidney; postoperative infection in the nephrectomy bed, and; renal carcinoma.The mechanism of fistula formation was clear in some of the cases.Those which developed following nephrectomy were likely due to ligation in mass of vessels, with subsequent necrosis of the wall and perforation.Similar changes occurred after direct trauma.In congenitallesions, the large vessels made up' the fistula.
Among the cases ofhypemephroma, there frequently existed both a connection of large artery to the vein due to tumor invasion, and large communicating vascular spaces within the partially necrotic tumor. 4In the remaining cases, the initiallesion probably was an arterial aneurysm which eventually eroded the wall of the vein to form the connection, but this condition is rare. 4  The literature has recorded more frequent involvement of the right postnephrectomy renal arteriovenous fistula because of the anatomic disposition of the right kidney and a short renal vein pedicle.Twothirds of the cases are found on the right side; removal of the kidney is technically more difficult on this side. 2,7,12,13  Like all peripheral arteriovenous fistula, they create a high venous return, an increase in cardiac output, and sometimes, a rise in systolic blood pressure.This leads to a reduction in peripheral resistance and a decrease in diastolic blood pressure.If the heart cannot compensate for this shunt while trying to meet increased tissue demands, high output cardiac failure will naturally result. 4 Postnephrectomy renal arteriovenous fistula must be suspected in alI patients with a history of previous nephrectomy when congestive heart failure and a high cardiac output state are present, especially if resistant to common medicaI treatment.2,14 The clinicaI presentation of this syndrome is very impressive because many patients have symptomatic congestive heart failure, high cardiac output, hypertension and continuous abdominal murmur. 4 With the clinicaI manifestations of an increased cardiac output, hyperthyroidism, anemia, beriberi heart disease, Paget' s disease and an intracardiac shunt as mentioned should be considered in the differential diagnosis.The pertinent clinicaI features of these various conditions will not be discussed at this time but a complete physical examinations, fluoroscopy ofthe chest, and a few laboratory studies will usually suffice to distinguish the various disorders.

,ll
The duplex scan ultrasound, helical.3-D (spiral) computer tomography and magnetic resonance angiographic images are alternative imaging modalities for the aorta and its branches, but definitive diagnosis is made by abdominal aortogram and selective renal arteriogram in case of the PNAVF. 1 ,2,4,14-16  Treatment can be accomplished through embolization or occlusion of the fistula through angiographic techniques, but the possibility of pulmonary emboli exists.Most surgeons prefer surgical excision and ligation of the fistula. 17-19 In our patient, we preferred surgical procedure to treat the arteriovenous fistula and the gallbladder lithiasis at the same time.We concluded that during nephrectomy,.the renal vessels should be ligated separately, and the transfixation in mass avoided in order to prevent the arteriovenous fistula.

Figure 1 -
Figure 1 -Percutaneous retrograde ,abdominal aortogram demonstrates dilated right renal artery, winding stump of the renal vein, and opacification of inferior vena cava.