## **Core Concept**
Renovascular hypertension is a type of secondary hypertension caused by **renal artery stenosis**, leading to decreased blood flow to the kidneys. This decrease triggers the **renin-angiotensin-aldosterone system (RAAS)**, resulting in increased blood pressure. The condition involves complex interactions between renal blood flow, hormonal regulation, and vascular resistance.

## **Why the Correct Answer is Right**
The correct answer, **ACE inhibitors**, can worsen renovascular hypertension in patients with bilateral renal artery stenosis or unilateral stenosis in a solitary functioning kidney. This is because ACE inhibitors block the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor that also stimulates aldosterone release. In the setting of reduced renal blood flow, the kidneys rely on angiotensin II to maintain glomerular filtration pressure. By inhibiting angiotensin II production, ACE inhibitors can reduce glomerular filtration rate (GFR) and potentially worsen renal function and hypertension.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Diuretics might affect blood pressure and fluid status but do not directly worsen renovascular hypertension by interfering with the compensatory mechanisms of the RAAS or renal blood flow.
- **Option B:** Beta-blockers can actually help manage hypertension by reducing cardiac output and renin release, not worsen it.
- **Option C:** Calcium channel blockers are generally used to treat hypertension and do not worsen renovascular hypertension; they can actually help manage blood pressure through vasodilation.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that patients with renovascular hypertension should be carefully evaluated before starting ACE inhibitors or angiotensin receptor blockers (ARBs), as these can precipitate acute kidney injury in the setting of bilateral renal artery stenosis or significant unilateral stenosis.

## **Correct Answer:** . ACE inhibitors