A 58-year-old man with end-stage renal disease secondary to diabetes mellitus began hemodialysis therapy in February 2003 through a left upper-extremity arteriovenous fistula. Hypertension was first diagnosed in 2000, and after starting dialysis therapy, systolic blood pressure (BP) was controlled at 150 mm Hg. However, in 2007 and 2008, BP increased to 190/90 mm Hg before, during, and after dialysis treatments despite attempts to reduce his dry weight and administration of maximal doses of nifedipine, valsartan, hydralazine, clonidine, labetalol, and doxazosin. The dialysate bath contained a calcium concentration of 3.0 mEq/L. The patient reported no previous abdominal trauma, surgery, or kidney biopsy. On physical examination, BP in the right arm was 190/90 mm Hg and BP in the right leg was 200/95 mm Hg. There were no vascular bruits and pulses were brisk and strong bilaterally. Blood tests showed a calcium concentration of 9.25 mg/dL (2.31 mmol/L), albumin level of 4.1 g/dL (41 g/L), intact parathyroid hormone level of 236.6 pg/mL, plasma renin activity of 0.65 ng/mL/h (0.18 ng/L/s), and aldosterone level of 98.7 ng/dL (2.74 nmol/L). Hematocrit was 31%, and he received 2,000 U/wk of erythropoietin. Echocardiography showed left ventricular hypertrophy. Color Doppler ultrasonography (Fig 1) and abdominal computed tomography (CT; Fig 2) were performed.
■ What is the differential diagnosis of refractory hypertension in a previously stable hemodialysis patient?
■ What testing would assist in this evaluation?
■ What diagnosis is suggested by the radiological test results?
■ What treatment is available for this patient?
Discussion
What is the differential diagnosis of refractory hypertension in a previously stable hemodialysis patient?
Hypertension is common in hemodialysis patients. Volume overload is the leading cause, and adequate volume management is essential. This requires restriction of sodium and fluid intake and careful ultrafiltration to an estimated dry weight. In the 20% of hypertensive hemodialysis patients unresponsive to ultrafiltration and maximal antihypertensive therapy, secondary causes should be explored. These include hypercalcemia, increased dialysate calcium concentration, secondary hyperparathyroidism, erythropoietin dosage, and traditional causes of secondary hypertension.
What testing would assist in this evaluation?
The patient was following a low-salt diet and gained less than 2.5% of body weight between dialysis sessions. Attempts to decrease his dry weight over 6 months were unsuccessful because of patient intolerance. One tool to monitor for subclinical volume overload is measuring the diameter of the inferior vena cava after dialysis.1 This did not suggest volume overload.
Other causes of hypertension were assessed. Erythropoietin therapy was discontinued, but without improvement. Coarctation of the aorta was less likely given the physical examination findings, and laboratory test results suggested that electrolyte causes were unlikely. On ultrasound, both kidneys were 9.5 cm in length, reducing suspicion for anatomic abnormalities.
What diagnosis is suggested by the radiological test results?
Color Doppler ultrasound (Fig 1) showed vascular flow in the lower pole of the left kidney (arrow) and color duplex imaging (not shown) indicated a low resistive index (0.58) there. Contrast-enhanced abdominal CT (Fig 2) further showed no other anatomic abnormalities except for an abnormal vascular lesion (arrow) in the left kidney. Computed tomographic angiography (Fig 3) suggested a left renal arteriovenous malformation (RAVM), confirmed by using angiography (Fig 4). Angiography did not yet show left renal artery stenosis. Left RAVM seems the most likely cause of this patient's refractory hypertension.
Figure 3. Oblique coronal maximum intensity projection computed tomographic angiography showed dilated vessels (large arrow) with early opacification of the renal vein (small arrow) in the left kidney.
Figure 4. Selective left renal digital subtraction angiography shows localized tortuous vascular channels (large arrow) in the lower pole of the left kidney with early filling of the left renal vein (small arrow) on the arterial phase.
RAVM is a rare (prevalence, <0.04%) and underrecognized cause of renovascular hypertension.2 It can be congenital, acquired, or idiopathic. Acquired RAVM is secondary to abdominal trauma, malignancy, or kidney biopsy. These risk factors were not present in our patient. Because the lesion was absent on prior imaging in 2003, this appears to be an idiopathic acquired lesion that emerged after hemodialysis. It is unclear whether the RAVM might be related in any way to hemodialysis.
Half the patients with RAVM develop hypertension.3 It has been postulated that local kidney ischemia triggers renin secretion and subsequent hypertension.3 However, much evidence shows that renal vein renin levels are normal without lateralization, and renal vein renin sampling is of little diagnostic value.3 Moreover, plasma renin activity measurement rarely is recommended.
Color Doppler duplex ultrasound allows rapid detection of vascular lesions within the kidneys. CT and angiography can confirm the diagnosis.
What treatment is available for this patient?
Treatment aims to cure the hypertension. Although nephrectomy and transcatheter embolization can be used to treat symptomatic RAVM, the literature provides limited evidence of its effectiveness for the treatment of hypertension secondary to RAVM.3 One study reported that hypertension was treated successfully in 62% of patients with RAVM.4 Nevertheless, the longer the patient has hypertension, the lower the cure rate.5 The cure rate depends on the duration of hypertension because long-term hypertension may lead to nephrosclerosis.4 Embolization also carries the risk of pulmonary embolism.4
In our patient, it was believed that the long-standing hypertension would not be responsive to correction of the RAVM, and the patient ultimately chose medical treatment. The case reminds nephrologists to carefully evaluate long-term hemodialysis patients with an acute change in hemodynamic parameters for potential secondary causes.
Final Diagnosis
Renovascular hypertension secondary to left renal arteriovenous malformation.
References
1. 1Jaeger JQ, Mehta TL. Assessment of dry weight in hemodialysis: An overview. J Am Soc Nephrol. 1999;10:392–403. MEDLINE
2. 2Cho KJ, Stanley JC. Non-neoplastic congenital and acquired renal arteriovenous malformations and fistulas. Radiology. 1977;129:333–343. MEDLINE
3. 3Purtak-Paschalis K, Januszewicz M, Rokicki A, et al.Arteriovenous fistula of the kidney: A case report of 47-year-old female patient treated by embolisation. J Hum Hypertens. 2003;17:293–296. MEDLINE |
CrossRef
4. 4Crotty KL, Orihuela E, Warren MM. Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas. J Urol. 1993;150:1355–1359. MEDLINE
Case provided and authored byYi-Chun Chen, MD,1,2 Yu-Chieh Su, MD,2,3 Chih-Wen Lin, MD,4 and Shang-Jyh Hwang, MD,51Division of Nephrology, Department of Internal Medicine, Buddhist Dalin Tzu Chi General Hospital, Chiayi; 2School of Medicine, Tzu Chi University, Hualien; 3Division of Hematology-Oncology and 4Department of Medical Imaging, Department of Internal Medicine, Buddhist Dalin Tzu Chi General Hospital, Chiayi; and 5Division of Nephrology, Department of Internal Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Address correspondence to Chih-Wen Lin, MD, Department of Medical Imaging, Buddhist Dalin Tzu Chi General Hospital, No. 2, Minsheng Rd, Dalin Township, Chiayi County 622, Taiwan. E-mail:dalinchiayi@yahoo.com.tw
FULL TEXT
00968-8/journalimage?img=PIIS0272638609009688.gr1.lrg.gif&fig=fig1&kwhquery=&issn=0272-6386&ishighres=false&allhighres=false&free=yes','journalimage');)
00968-8/journalimage?img=PIIS0272638609009688.gr2.lrg.gif&fig=fig2&kwhquery=&issn=0272-6386&ishighres=false&allhighres=false&free=yes','journalimage');)
00968-8/journalimage?img=PIIS0272638609009688.gr3.lrg.gif&fig=fig3&kwhquery=&issn=0272-6386&ishighres=false&allhighres=false&free=yes','journalimage');)
00968-8/journalimage?img=PIIS0272638609009688.gr4.lrg.gif&fig=fig4&kwhquery=&issn=0272-6386&ishighres=false&allhighres=false&free=yes','journalimage');)