Nephrol Dial Transplant (1999) 14: 2734-2737
© 1999 European Renal Association-European Dialysis and Transplant Association
Teaching Point
A young woman with high blood pressure on haemodialysis: it is never too late to evaluate hypertension
1 Institute for Pathology 2 and Department of Nephrology, University of Basel, Kantonsspital, Switzerland
Correspondence and offprint requests to: Prof. Dr. M. J. Mihatsch, Institute for Pathology, University of Basel, Kantonsspital, Schoenbeinstrasse 40, CH-4003 Basel, Switzerland.
Keywords: fibromuscular dysplasia; histology; hypertension; kidney; pathology; renal artery
Introduction
Once a patient is on haemodialysis long-term renal replacement therapy is usually needed because of irreversible nephron loss. Severe kidney disease accompanied by high blood pressure is often due to extensive glomerular injury. However, some patients do come off haemodialysis, making a careful clinical work-up mandatory to rule out curable disorders. Stenosis of the renal artery should be included into the differential diagnosis, since it is a reversible cause of severe hypertension and renal dysfunction. This important fact is underlined by the present case. We observed a young female with severe arterial hypertension and renal failure requiring haemodialysis. Haemodialysis could be stopped, once a dysplastic renal artery had been surgically revised and renal function and blood pressure had returned to normal limits.
Case report
A 28-year-old woman from Yugoslavia was admitted to the university hospital in Basel for dyspnea and headaches. In Yugoslavia she had been suffering from severe renal failure of unknown aetiology for the past 9 months. An underlying glomerulonephritis had been suspected. On admission the patient was in severe distress with pulmonary oedema and arterial hypertension (170/130 mmHg). She had pitting oedema of the lower extremities. The serum creatinine was 861 µmol/l and urea 395 µmol/l. The urinary sediment showed microscopic haematuria and proteinuria (dip stick +++). The patient was immediately placed on haemodialysis and aggressive ultrafiltration. The further work-up included an abdominal ultrasound and CT scan revealing a small right kidney (length 5.5 cm) and an 11-cm long left kidney. A subsequent angiogram of the left renal artery demonstrated an obstruction 3 cm distal to its origin (Figure 1
). Collateral capsular and lower pole vessels were well developed indicating that the disease process was not of acute onset. Blood flow in the small right kidney was slow, however, arterial abnormalities and stenoses were not observed. The occlusion of the left renal artery was surgically repaired by insertion of a saphenous vein graft, which was followed by recovery of urine output within minutes. A follow-up renal angiogram 9 days post-surgery revealed patency of the vascular graft and good arterial perfusion of the renal parenchyma (Figure 2). Intraparenchymal arteries were unremarkable. However, one lower pole branch immediately distal to the anastomotic site demonstrated segmental `beading', indicative of dysplasia (Figure 2). Within 2 weeks following surgery the serum creatinine had decreased to 89 µmol/l. The blood pressure ranged between 120 and 130 systolic and 80–90 diastolic. Urinalysis was normal except for mild proteinuria (dip stick +). Follow-up 4 months post-surgery confirmed stable renal function and normal blood pressure. The cause of the small right kidney remained undetermined; possibly, hypoplasia is the underlying condition.
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A segment of the left renal artery was resected and a needle biopsy of the left kidney was performed during surgery. The specimens were examined histologically.
Histopathology
Histological examination of the renal artery showed dysplastic changes. The arterial wall architecture was severely altered by deposition of fibrous tissue, focally `replacing' the outer half of the arterial wall, in particular the outer media (Figure 3). Higher power magnification revealed that smooth muscle cells were not eradicated, but highly atrophic and `strangulated' by collagen (Figure 4). Segmentally, connective tissue appeared to infiltrate from the outer portion of the media into the inner layers, sparing only small islands of muscle. In segments with better preserved media, rudimentary elastic lamellae were located amidst smooth muscle bundles separating the outer `longitudinal' from the inner `circumferential' portion (Figure 4). Structural changes were also found along the internal elastic lamina with partial fragmentation and loss (Figures 3 and 5). Connective tissue expanded the intima which showed features of fibroplasia along the outer aspect (alpha smooth muscle actin positive myofibroblasts) and an organized thrombus with iron deposition and neo-vascularization centrally (Figures 3 and 5). The radiographically observed vascular occlusion was due to thrombus formation. Arterial wall thinning or aneurysms were not present.
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The renal biopsy contained seven normal glomeruli lacking any light microscopical or immunohistochemical evidence of glomerulonephritis. Tubules, arterioles and small arteries were unremarkable. The interstitium revealed only mild patchy inflammatory fibrosis and minute foci of non-specific mononuclear cell infiltrates. Arcuate type arteries were not sampled.
Comment
Excessive persisting hypertension despite aggressive ultrafiltration prompted an intensive search for underlying renal vascular lesions which proved rewarding in this young lady who presented with (sub) acute renal failure. She had unilateral renal artery dysplasia with occlusion and became dialysis dependent because the contralateral kidney was hypoplastic.
Renal artery dysplasia mostly affects patients in their second or third decades, is more common among women and usually involves only one side. Renal veins remain unchanged [1]. The mechanisms leading to structural changes in the arterial wall are undetermined. It has been speculated that mechanical injury due to increased mobility of the kidney and stretching of the renal artery may lead to fibrous remodelling of the vessel wall [2,3]. However, this hypothesis seems unlikely because the carotid or iliac arteries are occasionally dysplastic as well [4]. Renal artery dysplasia seems progressive [5,6]: both the degree of stenoses and the lengths of involved arterial segments tend to increase with time. On follow-up of untreated cases, a decrease of renal size was observed in 62% of patients [5]. The frequency of total renal infarction was reported to be as high as 24% [5].
Fibromuscular dysplasia can be subtyped according to the arterial wall layer being most affected [7,8,9,10]:
- i. Intimal fibroplasia (rare; can be difficult to distinguish from non-specific fibrosis as seen in atherosclerosis)
- Medial `muscular' hyperplasia (rare).
- Medial fibroplasia with aneurysms (common: 60–70%; bilateral in 60%)
- Perimedial fibroplasia (common, 15–25%)
- Medial dissection (infrequent, 5–10%)
ii. Medial types;
iii. Adventitial fibroplasia (rare)
Medial fibroplasia with aneurysms (iiB) and perimedial fibroplasia (iiC) are the most common forms accounting for 75–95% of all cases. The histological changes observed in the case under discussion are consistent with a `perimedial' type. The extensive fibrous replacement of the outer portion of the media, the lack of aneurysms, the unilateral occurrence, thrombosis, and angiographic `beading' favour the perimedial variant [7]. Unusual features of the perimedial type in the current case are the segmental loss and fragmentation of the internal elastic lamina, elastic lamellae misplaced between smooth muscle bundles and fibroplastic thickening of the intima. Thus, our histological findings underline the great variability of patterns.
The long-term prognosis of our patient seems excellent, since recurrence of dysplasia after renovascular repair is exceptional [4], and because her intrarenal vessels were free of radiologically evident dysplastic changes. Intraparenchymal arteries may occasionally be the site of dysplastic alterations causing therapy resistent hypertension [11]. Although, dysplastic changes were found in our patient postoperatively in a non-repaired branch of the renal artery, progressive stenosis might be managed in the future by percutaneous transluminal angioplasty [6].
Teaching Point
- The possibility of renovascular lesions should be considered in young patients with apparent end-stage renal failure and severe hypertension despite aggressive ultrafiltration.
- Unilateral arterial dysplasia may cause renal failure if it induces hypertension and parenchymal damage in the contralateral kidney, or—as in this case—when the contralateral kidney is hypoplastic.
- Three categories of dysplastic arteries can be distinguished, but morphological subtyping is sometimes arbitrary.
References
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- Anderson GH Jr, Blackeman N, Streeten DH. The effect of age on prevalence of secondary forms of hypertension. J Hypertens 1994; 12: 609–615[Web of Science][Medline]
- Petit R, Delivigne J. Indication de la néphropexie: apports du néphrogramme isotopique et de l'artériographie rönale. Acta Urol Belg 1973; 41: 386–395[Medline]
- Kelly TF, Morris GC. Arterial fibromuscular disease. Observations on pathogenesis and surgical management. Am J Surg 1982; 143: 232–236[Web of Science][Medline]
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Goncharenko V, Gerlock AJ Jr, Shaff MI, Hollifield JW. Progression of renal artery fibromuscular dysplasia in 42 patients as seen on angiography. Radiology 1981; 139: 45–51
[Abstract/Free Full Text] - Lorelius LE, Hemmingsson A, Hagg A, Morlin C, Aberg H. Progressive fibromuscular dysplasia of the renal artery. Angiographic and clinical follow-up. Acta Radiol [Diagn] (Stockh) 1985; 26: 705–708[Medline]
- Olson JL. Hypertension: essential and secondary forms. In: Jennette JC, Olson JL, Schwartz MM, Silva FG, eds. Heptinstall's Pathology of the Kidney Lippincott-Raven, New York: 1998: 943–1001
- Harrison EG Jr, McCormack LJ. Pathologic classification of renal arterial disease in renovascular hypertension. Mayo Clin Proc 1971; 46: 161–167[Web of Science][Medline]
- Youngberg SP, Sheps SG, Strong CG. Fibromuscular disease of the renal arteries. Med Clin North Am 1977; 61: 623–641[Web of Science][Medline]
- Luscher T, Lie JT, Stanson AW, Houser OW, Hollier LH, Sheps SG. Arterial fibromuscular dysplasia. Mayo Clin Proc 1987; 62: 931–952[Web of Science][Medline]
- Holm-Bentzen M, Gerstenberg T, Horn T, Larsen S. Medical fibroplasia: involvement of renal artery and small renal arteries in renal vascular hypertension. Scand J Urol Nephrol 27; 1993: 263–265[Web of Science][Medline]
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