Internal Medicine · Year 3 · from Internal Medicine

Case 3: Secondary Hypertension - Renal Artery Stenosis

Patient Presentation

A 65-year-old man with a 20-pack-year smoking history and known peripheral arterial disease presents with new-onset hypertension at age 62. His blood pressure has been increasingly difficult to control despite multiple medications. He reports episodes of sudden shortness of breath ("flash pulmonary edema") that resolve without clear explanation.

Vital Signs

  • Blood Pressure: 178/102 mmHg
  • Heart Rate: 80 bpm
  • Respiratory Rate: 16/min

Physical Examination

  • General: Well-appearing
  • Cardiovascular: Abdominal bruit appreciated in right upper quadrant
  • Pulmonary: Clear
  • Extremities: Diminished pedal pulses bilaterally

Laboratory Results

  • Creatinine: 1.8 mg/dL (was 1.2 one year ago)
  • Potassium: 3.8 mEq/L
  • Urinalysis: Trace protein

Imaging

  • Renal duplex ultrasound: Right kidney 8.5 cm, left kidney 11 cm; elevated resistive indices on right

Clinical Image

Figure 3: MR angiography demonstrating severe right renal artery stenosis (arrow) due to atherosclerotic disease.

Image Source: Educational illustration for teaching purposes.

Questions

  1. What clinical features suggest renovascular hypertension in this patient?
  • A) Age of onset and family history
  • B) New-onset hypertension after age 55, flash pulmonary edema, asymmetric kidneys, abdominal bruit
  • C) Obesity and sleep apnea
  • D) Palpitations and sweating
  1. What are the two main causes of renal artery stenosis?
  • A) Diabetes and hypertension
  • B) Atherosclerosis and fibromuscular dysplasia
  • C) Glomerulonephritis and polycystic kidney disease
  • D) Aortic dissection and aneurysm
  1. What is the gold standard diagnostic test for renal artery stenosis?
  • A) Renal duplex ultrasound
  • B) CT angiography
  • C) Catheter-based renal angiography
  • D) Captopril renogram
  1. What precaution must be taken when using ACE inhibitors in patients with renal artery stenosis?
  1. When is revascularization indicated for atherosclerotic renal artery stenosis?

Answers

  1. B) New-onset hypertension after age 55, flash pulmonary edema, asymmetric kidneys, abdominal bruit - These are classic features of renovascular hypertension. Flash pulmonary edema (Pickering syndrome) occurs due to fluid retention in bilateral RAS or unilateral RAS with a solitary kidney.
  1. B) Atherosclerosis and fibromuscular dysplasia - Atherosclerotic RAS accounts for 90% of cases, typically in older patients with cardiovascular risk factors. FMD accounts for 10%, typically in younger women, and has a "string of beads" appearance.
  1. C) Catheter-based renal angiography - Digital subtraction angiography is the gold standard but is invasive. CT angiography and MR angiography are preferred for initial evaluation due to less invasiveness with good sensitivity and specificity.
  1. ACE inhibitor precautions in RAS:
  • In bilateral RAS or RAS in a solitary kidney, ACE inhibitors can cause acute kidney injury
  • Efferent arteriolar dilation reduces intraglomerular pressure needed to maintain GFR
  • Monitor creatinine within 1-2 weeks of starting ACE inhibitor
  • >30% rise in creatinine warrants discontinuation and further workup
  • ACE inhibitors may still be used in unilateral RAS with careful monitoring
  1. Indications for revascularization:
  • Resistant hypertension despite optimal medical therapy
  • Recurrent flash pulmonary edema
  • Progressive chronic kidney disease
  • Unstable angina with significant RAS
  • Recent trials (CORAL, ASTRAL) show limited benefit for revascularization over medical therapy in most patients
  • Best reserved for patients with clear clinical indications and >70% stenosis

Learning Points

  1. Hypertensive emergency requires IV medications and ICU monitoring with gradual BP reduction to prevent hypoperfusion injury.
  1. Resistant hypertension warrants screening for secondary causes, particularly primary aldosteronism (most common endocrine cause).
  1. Primary aldosteronism screening involves aldosterone-to-renin ratio; confirmatory testing and adrenal imaging guide treatment.
  1. Renovascular hypertension should be suspected with new-onset hypertension >55 or <30 years, flash pulmonary edema, or worsening kidney function on ACE inhibitors.
  1. Blood pressure goals are <130/80 mmHg for most adults with hypertension according to current guidelines.

All cases for this lecture as Markdown