questions 3

Renal Artery Stenosis

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Topic updated on 07/24/17 9:23pm

Snapshot
  • A 59-year-old man with a history of hypertension presents to his primary care physician for blood pressure management. He has tried lisinopril, hydrochlorothiazide, and losartan, and had minimal effect. He has a strong family history of cardiovascular disease. Physical examination is notable for a bruit in the right flank. Routine bloodwork shows an elevated creatinine. Preparations are made for a doppler ultrasound of the renal arteries.
Introduction
  • renal artery stenosisClinical definition
    • narrowing of one or both renal arteries
      • this often causes renovascular hypertension
      • grade 1 – RAS (Renal artery stenosis) with no clinical symptoms
      • grade 2 – RAS with controlled hypertension
      • grade 3 – RAS with resistant hypertension, abnormal renal function, or volume overload
  • Epidemiology
    • prevalence
      • 7% in the United States
      • present in up to 1/3 of patients with malignant or resistant hypertension
    • demographics
      • atherosclerotic disease
        • patients > 50 years of age
      • fibromuscular dysplasia
        • young women
    • risk factors
      • atherosclerosis and its risk factors (e.g., smoking and fatty diet)
      • fibromuscular dysplasia
      • kidney transplant patients
      • high calcium or phosphorous levels
      • high low-density lipoprotein cholesterol levels
  • Pathophysiology
    • pathophysiology
      • narrowing of artery lumen due to
        • atherosclerosis
        • fibromuscular dysplasia
      • narrowed arteries lead to reduced renal perfusion
        • reduced perfusion leads to activation of renin-angiotensin system
          • increased renin → hypertension, hypokalemia, and hyponatremia
        • bilateral renal stenosis can lead to volume overload
          • heart failure
          • pulmonary edema
  • Associated conditions
    • other manifestations of atherosclerotic disease
      • carotid artery disease
      • lower extremity artery disease
      • coronary heart disease
  • Prognosis
    • prognostic variable
      • negative
        • elevated serum creatinine
        • comorbid heart disease
        • comorbid chronic obstructive pulmonary disease (COPD)
    • survival with treatment
      • 91% at 1 year
      • 67% at 5 years
      • 41% at 10 years
Presentation
  • History
    • hypertension before 30 years of age
      • consider fibromuscular dysplasia in young women with abrupt onset of hypertension
    • resistant or malignant hypertension
    • worsening renal function after taking an ACE inhibitor or angiotensin receptor blocking (ARB) agent
      • may indicate bilateral RAS because ACE inhibitors and ARBs further decrease glomerular filtration rate and worsens renal function
    • sudden unexplained volume overload (heart failure or pulmonary edema)
  • Symptoms
    • primary symptoms
      • hypertension
  • Physical exam
    • extremities
      • may have edema if volume overloaded
    • abdomen
      • abdominal or flank bruit through systole and diastole
Imaging
  • Ultrasound
    • indications
      • often initial imaging in those < 60 years of age in patients with suspected RAS
    • sensitivity and specificity
      • sensitivity 88-93%
      • specificity 82-89%
  • CT angiography
    • indications
      • in patients with normal renal function and suspected RAS
    • sensitivity and specificity
      • sensitivity 90%
      • specificity 94%
  • MR angiography in patients with renal insufficiency
    • indications
      • in patients with renal insufficiency and suspected RAS
    • sensitivity and specificity
      • sensitivity 75-97%
      • specificity 64-93%
  • Invasive catheter angiography
    • indications
      • only indicated if high suspicion of disease but inconclusive imaging or if revascularization is planned
    • gold standard for diagnosis
Studies
  • Labs
    • serum creatinine to assess renal function
      • elevated creatinine may indicate atherosclerosis-associated RAS
      • normal creatinine may indicate fibromuscular dysplasia-associated RAS
    • urine protein to assess renal function
      • typically below nephrotic range (< 3.5 g in 24 hours)

  • Histology
    • fibromuscular dysplasia
      • medial fibroplasia
  • Diagnostic criteria
    • reduction of diameter of > 60%
    • string-of-beads appearance on angiography in fibromuscular dysplasia
Differential
  • Essential hypertension
    • typically responsive to therapy
  • Primary hyperaldosteronism
    • high levels of aldosterone
  • Obstructive sleep apnea
    • lethargy and fatigue
Treatment
  • Medical
    • ACE-inhibitors or ARBs
      • indications
        • persistent hypertension in patients with RAS
      • contraindicated in bilateral RAS or RAS in patients with single kidney
    • calcium channel blockers or β-blockers
      • given if patients do not respond to ACE-inhibitors or ARBs
    • manage lipid disorders with statins
  • Operative
    • revascularization
      • indications
        • severe complications of RAS
          • unexplained heart failure
          • unexplained pulmonary edema
          • chronic kidney disease
          • inadequately controlled hypertension
      • outcomes
        • may not improve outcomes in those with atherosclerotic RAS
        • cures up to 58% of hypertension in patients with fibromuscular dysplasia-associated RAS
      • complications
        • contrast-induced acute kidney injury or allergic reaction (< 3%)
        • bleeding, hematoma, or arteriovenous fistula
Complications
  • Renal dysfunction can progress to end-stage renal disease
    • incidence
      • 4% in one study of 68 adults over 39 months
    • treatment
      • dialysis and kidney transplant
 


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Qbank (2 Questions)

TAG
(M2.RL.174) A 69-year-old man with a 55-pack-year smoking history, diabetes type II, and hyperlipidemia presents to his primary care clinic for an annual exam. He has no complaints. He reports that his blood glucose has been under tight control and that he has not smoked a cigarette for the past 5 months. Vital signs are HR 69 bpm, BP 180/100 mm Hg, RR 12/min, and O2 saturation 99% on room air. Physical examination is notable for bruits bilaterally just lateral of midline near his umbilicus. You initiate an anti-hypertensive medication, but his blood pressure continues to be suboptimal. Creatinine is 3.5. Regarding this patient's disease, which of the following is the best initial step in management? Topic Review Topic

1. Reassure the patient that his high blood pressure is to be expected as he ages
2. Perform a renal angiogram
3. Renal ultrasound with Doppler
4. Perform revascularization with percutaneous transluminal angioplasty
5. Begin treatment with ACE inhibitors prior to any other workup

PREFERRED RESPONSE ▶
TAG
(M2.RL.4867) A 32-year-old woman presents to her primary care physician for a general wellness appointment. The patient has no complaints currently and just wants to be sure that she is in good health. The patient has a past medical history of asthma, hypertension, and anxiety. Her current medications include albuterol, fluticasone, hydrochlorothiazide, lisinopril, and fexofenadine. Her temperature is 99.5°F (37.5°C), blood pressure is 165/95 mmHg, pulse is 70/min, respirations are 15/min, and oxygen saturation is 98% on room air. On exam, you note a healthy young woman with a lean habitus. Cardiac exam reveals a S1 and S2 heart sound with a normal rate. Pulmonary exam is clear to auscultation bilaterally with good air movement. Abdominal exam reveals a bruit, normoactive bowel sounds, and an audible borborygmus. Neurological exam reveals cranial nerves II-XII as grossly intact with normal strength and reflexes in the upper and lower extremities. Which of the following is the best next step in management? Topic Review Topic

1. Raise lisinopril dose
2. Add furosemide
3. Ultrasound
4. CT of the abdomen
5. No additional management needed

PREFERRED RESPONSE ▶
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