WBR0813
| Author | [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Serge Korjian)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pharmacology |
| Sub Category | SubCategory::Renal |
| Prompt | [[Prompt::A 67-year-old man presents to the physician's office for high blood pressure. Physical examination is remarkable for elevated blood pressures and faintly audible abdominal bruits bilaterally. The physician orders a Doppler ultrasound and the diagnosis of high-grade bilateral atherosclerotic renal artery stenosis is made. The physician decides to initiate anti-hypertensive therapy. Which of following medications should be avoided in this patient?]] |
| Answer A | AnswerA::Furosemide |
| Answer A Explanation | AnswerAExp::Diuretics in general are not contraindicated in bilateral renal artery stenosis. |
| Answer B | AnswerB::Enalapril |
| Answer B Explanation | AnswerBExp::ACE-inhibitors are contraindicated in bilateral renal artery stenosis. |
| Answer C | AnswerC::Nifedipine |
| Answer C Explanation | AnswerCExp::Calcium channel blockers are not contraindicated in bilateral renal artery stenosis. |
| Answer D | AnswerD::Hydrochlorothiazide |
| Answer D Explanation | AnswerDExp::Diuretics in general are not contraindicated in bilateral renal artery stenosis. |
| Answer E | AnswerE::Metoprolol |
| Answer E Explanation | AnswerEExp::Beta-blockers are not contraindicated in bilateral renal artery stenosis. |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::
Angiotensin-converting enzyme inhibitors (ACEI) are contraindicated in patients with bilateral renal artery stenosis because they might cause acute kidney injury. In high-grade bilateral renal artery stenosis, the glomerular filtration rate (GFR) depends mostly on the action of angiotensin II (ANGII) depletion of extracellular fluid volume. ANGII regulates renal vascular resistance by activation of renin from the juxtaglomerular cells and the sympathetic nervous system to maintain renal blood flow (RBF) and GFR. It is important to remember that ANGII has a preferential vasoconstrictive role on the efferent arteriole (post-glomerulus) than the afferent arteriole (pre-glomerulus); this mechanism is normally advantageous because it maintains GFR when perfusion pressure decreases. The use of ACE-I and losing the capacity of ANGII to maintain GFR in patients whose renal perfusion is highly dependent on the action of ANGII, such as in bilateral renal artery stenosis or advanced renal disease, will lead to reduced GFR and renal impairment. Accordingly, ACE-I are contraindicated in bilateral renal artery stenosis. The same applies to angiotensin receptor blockers (ARBs) that have a similar effect. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::ACE inhibitor, WBRKeyword::Angiotensin converting enzyme, WBRKeyword::Bilateral renal artery stenosis, WBRKeyword::RAS, WBRKeyword::Hypertension, WBRKeyword::Bruit, WBRKeyword::ARB, WBRKeyword::Angiotensin receptor blocker |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |