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Patient Story

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A 14-year-old girl presents to your office for a routine physical examination. She has history of chronic headaches and complains about abdominal pain after eating. Her vital signs reveal a blood pressure of 163/100 mm Hg. Repeat manual blood pressure is 152/98 mm Hg. You obtain laboratory studies, which reveal a normal serum creatinine, mild hypokalemia, and elevated plasma renin activity and aldosterone level. Her renal ultrasound with Doppler is suspicious for right renal artery stenosis. You start hypertension management with a calcium-channel blocker and refer her to a pediatric nephrologist, who obtains a computed tomography angiography (Figure 71-1) that reveals severe narrowing of right renal artery. Her blood pressure remains sub-optimally controlled with calcium-channel blockers. An angiotensin II receptor blocker is added to her hypertension management.

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FIGURE 71-1

Stenosis of the right renal artery (arrow) on computed tomography angiography. (Used with permission from Halima Janjua, MD.)

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Introduction

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Renovascular hypertension is hypertension that results from lesions that impair blood flow to one or both kidneys. It is an important cause of reversible hypertension in children.

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Synonyms

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Renal artery stenosis; renovascular disease.

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Epidemiology

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  • Renovascular hypertension accounts for about 5 to 10 percent of hypertension in children.1,2

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Etiology and Pathophysiology

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  • Renovascular hypertension is caused by the interplay of renin-mediated mechanisms, sodium-related volume expansion, and increased sympathetic nervous system activity.

  • Specific causes of renovascular hypertension include:

    • Fibromuscular dysplasia.

    • Vasculitis (e.g., Takayasu’s disease, Polyarteritis nodosa, or Kawasaki disease).

    • Syndromes (e.g., Neurofibromatosis type 1, Tuberous sclerosis, Williams syndrome, or Marfan syndrome).

    • Umbilical artery catheterization.

    • Mid-aortic syndrome.

    • Renal artery hypoplasia.

    • Extrinsic compression (e.g., Neuroblastoma, Wilms tumor).

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Diagnosis

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Clinical Features
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  • The clinical presentation of renovascular hypertension can be very variable.

  • Children can be asymptomatic and incidentally found to have severe hypertension or they can present with symptoms secondary to end-organ damage from severe hypertension.

  • An abdominal or flank bruit, signaling turbulent blood flow, may be heard on physical exam.

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Laboratory Testing
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  • Increased plasma renin activity (PRA)—PRA may be elevated in children with renovascular hypertension.

  • Hyperaldosteronism—Aldosterone may be elevated due to activation of rennin-angiotensin-aldosterone system.

  • Hypokalemia—May be seen due to effect of aldosterone.

  • Metabolic alkalosis—May be seen due to effect of aldosterone.

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Imaging
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  • Doppler Ultrasonography—Renal arteries and its branches can be viewed by color and pulsed-wave Doppler. Ultrasonography allows for measurement of peak systolic velocities in the intrarenal branches, although this study may not be sensitive enough to detect distal sites of stenosis.3

  • Computed Tomography Angiography (CTA)—It provides three-dimensional images. It has better spatial resolution compared to magnetic resonance angiography (MRA). This study ...

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