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Saudi Journal of Kidney Diseases and Transplantation
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CASE REPORT  
Year : 2015  |  Volume : 26  |  Issue : 4  |  Page : 778-782
Renal artery stenosis: An unusual etiology of hypertensive encephalopathy in a child with fanconi anemia


1 Department of Pediatric Medicine, Nil Ratan Sircar Medical College and Hospital, Kolkata, West Bengal, India
2 Department of Radiology, Nil Ratan Sircar Medical College and Hospital, Kolkata, West Bengal, India

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Date of Web Publication8-Jul-2015
 

   Abstract 

A 9-year-old girl, diagnosed case of Fanconi anemia, presented with generalized convulsion with altered sensorium. She had fever, severe pallor, sinus tachycardia, blood pressure of 180/120 mmHg in both upper and lower limb, pan-systolic murmur of grade 2/6, abdominal bruit and bilateral papilledema. A provisional diagnosis of hypertensive encephalopathy was made and managed with continuous labetalol infusion. Detailed evaluation including magnetic resonance angiography of renal artery detected underlying atrophic and non-functioning right kidney secondary to severe renal artery stenosis on the same side. She was started with multiple antihypertensives, but her blood pressure was maintained poorly. Later on, she underwent rightsided nephrectomy. Following surgery, she was doing well and maintaining normal blood pressure without any antihypertensives. Our child is the second reported case of Fanconi anemia associated with renal artery stenosis presenting with hypertensive encephalopathy.

How to cite this article:
Purkait R, Mukherji A, Datta S, Bhadra R. Renal artery stenosis: An unusual etiology of hypertensive encephalopathy in a child with fanconi anemia. Saudi J Kidney Dis Transpl 2015;26:778-82

How to cite this URL:
Purkait R, Mukherji A, Datta S, Bhadra R. Renal artery stenosis: An unusual etiology of hypertensive encephalopathy in a child with fanconi anemia. Saudi J Kidney Dis Transpl [serial online] 2015 [cited 2020 Jun 1];26:778-82. Available from: http://www.sjkdt.org/text.asp?2015/26/4/778/160215

   Introduction Top


Fanconi anemia is the most common form of constitutional aplastic anemia and is inherited as an autosomal recessive condition. Most patients have short stature, growth failure, hyperpigmentations and/or cafe΄ au lait spots and skeletal abnormalities. Absent, misshapen or supernumerary thumbs and dysplastic radii occur in half of the patients. Renal anomalies, like absent, ectopic, misshapen or horseshoe kidney, are detected in 21% of patients. [1] But, association with renal artery stenosis is rare. To the best of our knowledge, only one case of Fanconi anemia associated with renal artery stenosis has been reported in the literature. [2]


   Case Report Top


A 9-year-old girl was admitted with complaints of fever, headache and vomiting for three days and two episodes of generalized convulsions on the day of admission. On examination, she had fever, pallor, altered sensorium with Glasgow coma scale of E2M1V3 and no signs of meningeal irritation. There were no focal neurological signs. Fundoscopic examination showed bilateral papilloedema. She had a sinus tachycardia of 120/min and blood pressure of 180/120 mm Hg in both upper and lower limbs. A pan-systolic murmur of grade 2/6 was heard on the left sternal border. Auscultation of the abdomen revealed bruit. Past medical records disclosed that she has been diagnosed as Fanconi anemia based on a chromosomal breakage study when she was five years old.

Initial investigation revealed hemoglobin of 6.3 g/dL (normal children 11.5-15.5 g/dL), white cell count of 4.3 × 10 3 /μL (normal children 4.5-13.5 × 10 3 /μL) and platelets 150 × 10 3 /μL (normal children 150-400 × 10 3 /μL). Liver function tests, blood urea nitrogen, serum creatinine, serum electrolytes and routine urine examination were within the normal limit. Left ventricular hypertrophy secondary to persistent arterial hypertension was evident on echocardiography. The cranial computed tomography (CT) scan was normal and lumbar puncture revealed an elevated cerebrospinal fluid pressure of 300 mm but with normal protein content and microscopy.

Her blood pressure was controlled with continuous labetalol infusion and she regained consciousness with no further fits. She was then started with combination oral antihypertensive therapy with labetalol, amlodepine, spironolactone and enalapril, but maintained blood pressure poorly. Anemia was corrected with packed cell transfusion. Considering the age of the child, clinical presentation, physical examination and absent family history of hypertension, her hypertension was thought to be secondary to renal origin and she was then advised for detailed investigation accordingly.

Color Doppler ultrasound (CDUS) revealed an abnormally small (5.2 cm) right kidney with high peak systolic velocity of 211 cm/s and the right intrarenal flow was flattened, with a "parvus et tardus" pattern, characteristic for a high-degree stenosis [Figure 1]. The left kidney was normal-sized (9.5 cm) without sonographic evidence of renal artery stenosis. This finding was confirmed with renal magnetic resonance angiography (MRA), which revealed atrophic right kidney and severe stenosis in the right renal artery [Figure 2]. The other arteries (abdominal aorta, left renal artery, celiac artery, mesenteric arteries and periphery arteries) were normal. The child then underwent Captopril-enhanced renal scintigraphy with 99m technetium-diethylene triamine penta-acetic acid (99mTc-DTPA) for functional evaluation, which showed severely compromised renal function (<10% of total renal function) and reduced glomerular filtration rate (GFR) (<7 mL/min) on the right.We could not measure renal vein renin activity as the facility for the same is not available at our center. But, we did measure the peripheral plasma renin activity, which was elevated. Accordingly, a urosurgeon was consulted and the child underwent right-sided nephrectomy. Following surgery, her blood pressure started to regress and became normal and was without any antihypertensive on the follow-up visit at three months; peripheral plasma renin activity came down to the normal level. The child was kept under regular follow-up.
Figure 1: (a) Doppler frequency spectrum documents high systolic flow velocity of 211 cm/s and (b) the right intrarenal flow was flattened, with a "parvus et tardus" pattern, characteristic for a high-degree stenosis.

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Figure 2: (a) Right-sided atrophic kidney and (b) severe stenosis in the right renal artery 6 cm away from its origin from the abdominal aorta.

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   Discussion Top


Systemic hypertension is less common in children than in adults, although the incidence seems to be rising recently. Unlike adults, 70- 80% of hypertension in children is secondary to renal abnormalities; cardiovascular disease or endocrinopathies are additional etiologies. Renal or renovascular hypertension (RVH) accounts for approximately 90% of children with secondary hypertension. [3]

Renal artery stenosis is the most common potentially curable cause of RVH, which is often secondary to arteriosclerosis or fibromuscular dysplasia. The location of atherosclerotic disease is most often at the origin of the renal artery. But, fibromuscular dysplasia is classically located away from the origin of the renal artery, often in the midportion of the vessel or at the first arterial bifurcation. Manifestations of renal artery stenosis may vary from a purely "incidental" finding noted during angiography for other peripheral vascular diseases to advancing renal failure leading to the need for dialysis. Studies showed that more than 70% of luminal obstruction needs to be present to manifest clinically significant renal artery stenosis. Development of systemic hypertension due to underlying renal artery stenosis shares a complex pathophysiologic mechanism, which starts with increased secretion of renin from the juxtaglomerular cells of the afferent arterioles of the ischemic kidney. Renin acts on angiotensinogen to form angiotensin I. Angiotensin-converting enzyme (ACE) then converts angiotensin I to form angiotensin II. Angiotensin II is a potent arterial vasoconstrictor. It also stimulates the zona glomerulosa of the adrenal glands to secrete aldosterone, thereby increasing sodium retention, which further increases blood pressure. GFR in the affected kidney is thus initially maintained by increasing systemic blood pressure. But, as the stenosis progresses, this compensatory mechanism fails to maintain GFR on the affected side, thereby setting up a vicious cycle. In patients with unilateral renal artery stenosis and a normal contralateral kidney, no clinically detectable change in renal function is observed due to the effective compensation of the normal kidney. But, in bilateral renal artery stenosis and those with solitary kidney, patients may land up with renal failure. [4]

Early diagnosis of renal artery stenosis is an important clinical objective as interventional therapy can improve or cure hypertension and preserve renal function. The gold standard technique for renal artery stenosis diagnosis is intra-arterial digital subtraction angiography; however, it remains unsuitable for renal artery stenosis screening because it is an invasive and expensive method. MRA and CT angiography are promising alternative techniques, which are also expensive and not widely available. However, the major limitation of conventional MRA and CT angiography is that they only provide anatomical information about renal artery stenosis and cannot document whether a stenosis is severe enough to cause a pressure gradient, trigger renin release and subsequent renovascular hypertension. Studies have shown that CDUS, although highly operator-dependent, can be an effective tool in the diagnosis of renal artery stenosis. CDUS imaging is a simple, safe (non-invasive) and widely available technique; in addition, the procedure is painless and well tolerated by patients. The most reliable approach to detect severe renal artery stenosis by CDUS is the combined use of a direct parameter such as a peak systolic velocity (PSV) >200 cm/s or the renal/aortic ratio (RAR) >3.5 and an indirect parameter, most likely the side-to-side difference of the resistance index (RI). [5],[6] Captopril-enhanced renal scintigraphy with 99mTc-DTPA is also a less-invasive and widely accepted screening tool for the diagnosis of hemodynamically significant renal artery stenosis, but sensitivity and specificity are 68% and 92%, respectively.7

The optimal treatment of hypertension due to unilateral renal artery stenosis remains uncertain. In recent years, due to advancement of newer antihypertensive drugs and the development of percutaneous transluminal renal angioplasty (PTA) with the implanting of "stents," nephrectomy becomes the worst therapeutic option.8 Surgical correction is preferred in those patients who fail or refuse angioplasty, as lifelong medical therapy is less desirable in the typically young patients with this disorder. Because of limited existing data, specific guidelines cannot be made regarding the indication of nephrectomy of unilateral atrophic kidney in patients with RVH having refractory blood pressure or deterioration of the renal function, and where the revascularization of the artery is no longer possible. Marboeuf et al9 observed in their retrospective study that following nephrectomy, there was spectacular improvement in blood pressure, but insignificant improvement in renal function when compared with revascularization. In another retrospective study of 51 patients with RVH performed by Thomaz et al,[10] it was found that removal of the atrophic kidney results in improvement of the arterial hypertension and of the renal function in two-thirds of patients. Both the authors proposed in their articles that nephrectomy could be the treatment option in selected patients with resistant hypertension where the renal artery stenosis has resulted in non-functioning (<10% of total renal function) atrophic kidneys and hypersecretion of renin (ratio>1.5 in relation to the contralateral kidney).[9],[10]

Conflict of interest: None

 
   References Top

1.
Segel GB, Lichtman MA. Aplastic anemia: Acquired and inherited. In: Kaushansky K, Lichtman MA, Beutler E, Kipps TJ, Seligsohn U, Prchal JT, eds. William Hematology. 8 th New York: McGraw Hills; 2010. p. 475-9.  Back to cited text no. 1
    
2.
Vowels M, Hughes DO, Beveridge J. Renal artery stenosis with hypertension in Fanconi's cytopenia. Med J Aust 1970;1:173-7.  Back to cited text no. 2
[PUBMED]    
3.
Lande MB. Systemic hypertension. In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, Behrman RE, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia: Saunders; 2012. p. 1639-47.  Back to cited text no. 3
    
4.
Textor SC. Renovascular hypertension and ischemic nephropathy. In: Brenner BM, edr. Brenner and Rector's the Kidney. 8th ed. Philadelphia: Saunders; 2008. p. 1528-66.  Back to cited text no. 4
    
5.
Drieghe B, Madaric J, Sarno G, et al. Assessment of renal artery stenosis: Side-by-side comparison of angiography and duplex ultrasound with pressure gradient measurements. Eur Heart J 2008;29:517-24.  Back to cited text no. 5
    
6.
Spyridopoulos TN, Kaziani K, Balanika AP, et al. Ultrasound as a first line screening tool for the detection of renal artery stenosis: A comprehensive review. Med Ultrason 2010;12:228-32.  Back to cited text no. 6
    
7.
Johansson M, Jensen G, Aurell M, et al. Evaluation of duplex ultrasound and captopril renography for detection of renovascular hypertension. Kidney Int 2000;58:774-82.  Back to cited text no. 7
    
8.
Kashyap VS, Schneider F, Ricco JB. Role of interventions for atherosclerotic renal artery stenoses. J Vasc Surg 2011;54:563-70.  Back to cited text no. 8
    
9.
Marboeuf P, Delsart P, Hurt C, et al. Management of renal atrophy in hypertensive patients: Experience in Lille. Presse Med 2010;39:e67-76.  Back to cited text no. 9
    
10.
Thomaz MJ, Lucon AM, Praxedes JN, Bortolotto LA, Srougi M. The role of nephrectomy of the atrophic kidney in bearers of renovascular hypertension. Int Braz J Urol 2010;36:159-70.  Back to cited text no. 10
    

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Correspondence Address:
Radheshyam Purkait
Department of Paediatric Medicine, Nil Ratan Sircar Medical College and Hospital, Kolkata, West Bengal
India
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DOI: 10.4103/1319-2442.160215

PMID: 26178556

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    Abstract
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