Renal artery stenosis

Diagnosis of Renovascular Hypertension

Cholatip Pongskul

Characteristics of atherosclerotic and fibromuscular dysplasia

Variable Atherosclerotic Fibromuscular dysplasia

Age at presentation Older(>50 yr) Usually young(<40 yr)

Sex Either Usually female

Lesion location Ostial, proximal, middle Middle or distal

BP response to revascularization

Unclear Normotensive in most patients

Atherosclerotic Fibromuscular dysplasia

Elderly>50 Younger<40,femaleResponse to correction

Pathophysiology of renal artery stenosis

Who should be tested for renovascular hypertension?

• 45-year-old man, uremia, BP 160/90 mmHg, proteinuria, kidney 8.5, 8 cm

• 70-year-old man, smoker, hypertension, dyslipidemia, presented with pulmonary edema, Cr=1.4 mg/dl

• 60-year-old woman with pulmonary edema, BP 180/100 mmHg, Cr=1.2 mg/dl

Who Should be tested

What testShould be performed

How

to interpret the result

Who

• Onset of severe hypertension after 55• Unexplained deterioration of kidney function

– Rising > 50%, 1 week, ACEI• Severe hypertension in diffuse atherosclerosis• Severe hypertension with asymmetry kidney >

1.5 cm• Severe hypertension with flash pulmonary

edema, refractory CHF• Systolic-diastolic bruit at one side

Test or not test?

• Medication is effective in renovascular hypertension

• Who will benefit from correction?

• Testing associated with potential risk• Correction procedure associated with

morbidity/mortality

Test should be performed in patient with high likelihood of benefit

from procedure

High likelihood of benefit from procedure

• Short duration• Failure of medical Rx, in patient with high

likelihood of renovascular hypertension• Intolerance to optimal medical therapy• Progressive renal failure• Suspected fibromuscular dysplasia• Recurrent flash pulmonary edema

Gold Renal angiography

More than 50% stenosis

Other tests• Duplex sonography• CT angiogram• MRA

Duplex doppler sonography

Functional and anatomical

Peak200 cm/sec

Peak systolic velocitySensitivity 85, specificity 92%Positive predictive value 84%

Positive test: more informative than negative test

Resistive index(1-end diastolic velocity)/PSV

Predict outcome after revascularization

Limitation

Time consuming operator dependent

Obese patient

CT angiography

Excellent sensitivity and specificityLimitation in distal stenosis (FMD)

Magnetic resonance angiography

MRA• Almost 100% sensitivity!• Nephrogenic systemic

fibrosis?

Functional assessment

Captopril renography: less commonly usedLittle predictive value

Not for screening test!

Selecting a diagnostic test

• Local availability• Expertise with each technique• Renal insufficiency?

Who

New onset HT>55 yrDeterioration GFRAsymmetry kidneyFlash pulmonary edema

Test

Failure medicalFMD?Progressive renalfailure

Benefit fromcorrection