What is the next investigation for an elderly patient with uncontrolled Hypertension (HTN) and renal artery stenosis, who has undergone ultrasonography showing a small left kidney and renal arteriography?

Next Investigation for Elderly Patient with Uncontrolled Hypertension and Renal Artery Stenosis

For an elderly patient with uncontrolled hypertension despite multiple medication trials, small left kidney on ultrasound, and renal artery stenosis on arteriography, balloon angioplasty (option D) is the next appropriate step rather than additional imaging.

Rationale for Balloon Angioplasty

The patient already has confirmed renal artery stenosis through arteriography, which is considered a definitive diagnostic test. The clinical scenario presents several high-risk features that warrant intervention:

1. Uncontrolled hypertension despite multiple medication trials
2. Evidence of end-organ damage (small left kidney)
3. Confirmed renal artery stenosis on arteriography

According to the 2024 ESC guidelines, renal artery revascularization should be considered in patients with:

• Atherosclerotic unilateral >70% RAS
• Concomitant high-risk features (including treatment-resistant hypertension)
• Signs of kidney viability 1

Why Additional Imaging is Not Indicated

The options A (Renal CTA), B (Renal MRA), and C (Retrograde pyelography) represent additional diagnostic imaging, which is unnecessary when:

• Renal artery stenosis has already been confirmed by arteriography
• The patient has clinical indications for intervention (uncontrolled hypertension)
• The patient shows evidence of end-organ damage (small left kidney)

The 2024 ESC guidelines clearly state that duplex ultrasound is recommended as first-line imaging, followed by MRA or CTA if duplex is inconclusive 1. In this case, arteriography has already been performed, which provides definitive diagnosis of renal artery stenosis.

Assessment of Kidney Viability

Before proceeding with balloon angioplasty, assessment of kidney viability is important:

Parameter	Signs of viability	Signs of non-viability
Renal size	>8 cm	<7 cm
Renal cortex	Distinct cortex (>0.5 cm)	Loss of corticomedullary differentiation
Proteinuria	Albumin-creatinine ratio <20 mg/mmol	Albumin-creatinine ratio >30 mg/mmol
Renal resistance index	<0.8	>0.8

The small left kidney may indicate chronic ischemia, but intervention could still benefit blood pressure control even if full recovery of kidney function is unlikely.

Revascularization Benefits

The European Society of Cardiology recommends considering renal artery revascularization when:

• There is >70% stenosis with high-risk clinical features
• The patient has treatment-resistant hypertension
• There are signs of kidney viability 1

Balloon angioplasty with stenting (when indicated) is the preferred revascularization method for atherosclerotic renal artery stenosis.

Post-Procedure Management

Following balloon angioplasty:

• Initial follow-up at 1 month
• Subsequent follow-up every 12 months or when new symptoms arise
• Monitoring should include blood pressure control, renal function, and duplex ultrasound 1

Common Pitfalls to Avoid

1. Delaying intervention with unnecessary additional imaging when diagnosis is already established
2. Failing to recognize high-risk features that warrant intervention
3. Not assessing kidney viability before intervention
4. Inappropriate discontinuation of ACE inhibitors/ARBs when mild creatinine elevation occurs

In summary, this patient has already undergone diagnostic confirmation with arteriography, and the clinical picture strongly supports proceeding directly to balloon angioplasty rather than obtaining additional imaging studies.