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

Next Investigation for Renal Artery Stenosis in Uncontrolled Hypertension

Balloon angioplasty (D) is the next appropriate step for this elderly patient with uncontrolled hypertension, small left kidney, and confirmed renal artery stenosis on arteriography.

Rationale for Balloon Angioplasty

The patient presents with a classic case of renovascular hypertension that has already been confirmed through:

• Long-standing uncontrolled hypertension despite multiple drug treatments
• Ultrasonography showing small left kidney (suggesting chronic ischemia)
• Renal arteriography already confirming renal artery stenosis

At this point, further diagnostic imaging would be redundant since:

1. The diagnosis of renal artery stenosis has already been established by arteriography, which is considered a gold standard diagnostic test 1
2. The patient has clear clinical indicators of hemodynamically significant stenosis (uncontrolled hypertension and small kidney)
3. The patient has failed medical management, meeting criteria for intervention

Evidence-Based Management Algorithm

Step 1: Confirm Hemodynamically Significant Stenosis

• The patient already has arteriographic confirmation of stenosis
• Small kidney on ultrasound indicates chronic ischemic changes
• Uncontrolled hypertension despite multiple medications suggests hemodynamic significance

Step 2: Determine Appropriate Intervention

According to the 2017 ESC guidelines, renal artery angioplasty should be considered for patients with:

• Hemodynamically significant renal artery stenosis
• Resistant hypertension
• Hypertension with unexplained unilaterally small kidney 1

Step 3: Proceed with Revascularization

• Balloon angioplasty is the appropriate next step, potentially with stenting depending on the nature of the stenosis
• For atherosclerotic lesions (likely in an elderly patient), stenting is often added to angioplasty 1

Why Not Other Options?

• Renal CTA (A): Redundant as arteriography has already confirmed stenosis. Digital subtraction angiography (DSA) is considered the gold standard for diagnosis of renal artery stenosis 1.

• Renal MRA (B): Unnecessary when arteriography has already been performed. MRA is a non-invasive diagnostic tool used before confirmation by angiography, not after 1.

• Retrograde pyelography (C): Not indicated for renal artery stenosis evaluation. This technique evaluates the collecting system, not the vascular supply 1.

Clinical Considerations and Pitfalls

1. Monitor renal function: Patients may experience transient worsening of renal function after revascularization, especially if they are on ACE inhibitors or ARBs 1.

2. Blood pressure management: Following revascularization, most patients will still require antihypertensive medications, though often at reduced doses 2.

3. Follow-up surveillance: After angioplasty, regular monitoring is essential as restenosis can occur in 15-24% of treated patients 1.

4. Medication adjustments: ACE inhibitors or ARBs that may have been contraindicated or caused renal deterioration can often be safely reintroduced after successful revascularization 1.

5. Beware of false negatives: Diagnostic tests like duplex ultrasonography can sometimes miss significant stenosis, as highlighted in case reports 3.

The patient's presentation with uncontrolled hypertension, small kidney, and confirmed renal artery stenosis on arteriography represents a clear indication for proceeding with revascularization rather than additional diagnostic testing.