An otherwise healthy 19-year-old woman comes to clinic for a

[kailash]

An otherwise healthy 19-year-old woman comes to clinic for a routine health check. She complains of episodic headaches as well as occasional palpitations. A blood-pressure check at that time reveals a pressure of 190/110 mm Hg. Physical examination reveals an abdominal bruit heard over the lower abdominal quadrants. Because the patient has previously had normal blood pressures and has no family history of hypertension, an extensive search for secondary causes of hypertension is undertaken. Magnetic resonance angiography confirms the suspicion of bilateral fibromuscular dysplasia. Which of the following antihypertensive agents, if used, should be used with the most utmost vigilance in this patient?

A. Amlodipine
B. Clonidine
C. Fosinopril
D. Hydrochlorothiazide
E. Metoprolol

[kailash]

C. Fosinopril

[subhda]

The answer is C.
Bilateral renal ischemia leads to sodium retention with an increase in extracellular fluid volume because of the activation of the renin-angiotensin-aldosterone system. However, lowering the mean blood pressure will reduce the intraglomerular pressure because of renal artery stenosis. The normal autoregulatory response maintains the intraglomerular pressure by angiotensin-II mediated preferential increase in resistance at the postcapillary arteriole. Blocking angiotensin II formation with an ACE inhibitor will blunt this response and reduce the GFR. The effect is more pronounced with diuretic-induced volume depletion, which makes maintenance of the GFR more angiotensin II dependant. Therefore, the combination of an ACE inhibitor and a diuretic can control the hypertension and is likely to be more effective than other antihypertensive agents; however, this may lead to a decline in GFR causing the serum creatinine to rise. ACE inhibitors are not contraindicated as long as the patient is carefully monitored.

Other agents—calcium channel blockers such as amlodipine (choice A), centrally acting sympathetic agents such as clonidine (choice B), thiazide diuretics such as hydrochlorothiazide (choice D), or beta-blocking agents such as metoprolol (choice E)—are generally acceptable choices. All drugs must be used with care because patients with severe bilateral renal artery disease may have a decline in GFR with any antihypertensive drug