Management of Renal Artery Stenosis

1. Management of Renal Artery Stenosis Kent MacKenzie, MD Division of Vascular Surgery McGill University Montreal, Quebec

2. Disclosures None

4. Atherosclerotic RAS • Often orificial/ostial • Associated aortic atherosclerosis • Associated atherosclerosis elsewhere • Coronary • Carotid • Peripheral • Fibrointimal Hyperplasia (FMD)

5. Atherosclerotic RAS • Clinical Consequences • Hypertension • Ischemic nephropathy • Chronic renal failure • Dialysis

6. Hypertension

7. Hypertension • Picture Renin-AII-Ald

8. Angiotensin II • Vasoconstriction • Sodium Retention • Aldosterone Release

9. Sustained HTN • Adaptive changes  PVR • Heart • Arteries • Endothelial dysfunction •  Nitrous oxide

10. The presence of hypertension is considered a prerequisite for renal artery intervention.

11. Diagnosis of RAS • Hemodynamically significant lesion in renal artery in a patient with HPTN • Pressure gradient • Diagnosis depends on identifying: • a pressure gradient • surrogate of a pressure gradient • Functional surrogate • Imaging surrogate

12. Functional Studies • Intravenous Pyelography • Differential Renal Function Studies • Plasma Renin Activity • Simulated Plasma Renin Activity • Renal Vein Renin • Catpopril Renal Scintography

13. Functional Studies

16. Functional Studies - Screening

17. Imaging Diagnosis • Imaging surrogates for hemodynamic RAS • Duplex ultrasound • CT • MRA • Angiography

18. CT Angio • Minimally invasive • Calcification artifact

19. MRA • NSF • ?overestimates • experience

20. Duplex Ultrasound • PSV criteria • PSV RA/Aorta ratios Picture

21. Angiography • ? Smaller contrast load • Allows intervention

22. Imaging Diagnosis of RAS

23. In Practice • High likelihood of RAS • Good clinical indications for intervention • Duplex ultrasound • Ad-hoc Diagnostic +/- Therapeutic renal arteriography

24. Indications for Revascularization The presence of hypertension is considered a prerequisite for renal artery intervention.

25. Revascularization • Potential Indications for renal revascularization • Incidental , asymptomatic RAS with need for aortic reconstruction • RAS with renal dysfunction alone • RAS with hypertension • RAS with hyperpertension and renal dysfunction • RAS with angina • RAS with recurrent flash pulmonary edema Chronic HPTN issues Acute HPTN issues

26. Revascularization with aortic surgery (prophylactic) • 69 y.o. patient requires: • Open AAA repair • Endo AAA repair • Aortofemoral bypass for occlusive dx. • Incidental imaging finding of severe RAS • No severe HPTN at diagnosis

27. Revascularization with aortic surgery (prophylactic) • 100 hypothetical patients with unsuspected RAS who will undergo aortic surgery • 44% (44 patients) lesion progression and RVH • 36% (16 patients) may develop preventable reduction in renal function • 66% (11 patients) will demonstrate restored function with delayed renal treatment Hansen KJ et al

28. Revascularization with aortic surgery (prophylactic) • Therefore only 5 patients (5%) will gain a unique benefit from prophylactic renal artery repair • Risk of adverse event with combined aortic/renal revasc. • 5-6% mortality in the best hands • 3-4% late failure of operative repair • Therefore, prophylactic renal revasc. will potentially result in benefit in 5% of patients yet an adverse outcome in 10% Hansen KJ et al

29. Revascularization with aortic surgery (prophylactic) • Prophylactic renal revascularization alone or in conjunction with aortic reconstruction is therefore not indicated • Surgical reconstruction • Catheter-based reconstruction Hansen KJ et al

30. Renal Insufficiency and RAS • The absence of hypertension in a patient with RAS and excretory dysfunction suggests the presence of severe parenchymal disease • Without HPTN, response to revascularization is poor

31. RAS and Hypertension alone • Treatment is empiric • Expectation of clinical improvement is less • Unilateral vs. Bilateral RAS • Hypertension response is poorly predictable

32. Hypertension with Renal Insufficiency • Accumulated experience has resulted in a paradigm shift in approach to selecting patients for intervention • Surgical literature PTA • RAS and severe HPTN as a pre-intervention predictor of response • Changes in renal function post-intervention being the short-term outcome • Improvements in all-cause cardiovascular outcomes being the outcome of interest in trials evaluating RA intervention

33. Hypertension with Renal Insufficiency All patients

34. Hypertension with Renal Insufficiency

35. Hypertension with Renal Insufficiency

36. Hypertension with Renal Insufficiency • Treatment of hemodynamically significant RAS in a patient with: • Hypertension (severe) • Rapidly progressive decline in renal function • Salvageable renal mass • Surgical literature suggests expectation of improved BP control and reduction in rate of functional loss

37. RAS with angina or pulm edema • Acute myocardial strain • Acute episodes of severe hypertension • Multiple case-series suggesting significant stabilzation of cardiac status after renal revascularization

38. Options for Intervention • Surgical Revascularization • Renal/aortic endarterectomy • Renal artery bypass • Direct • Aortorenal bypass, iliorenal bypass • Renal artery reimplantation • Indirect • Hepatorenal bypass • Splenorenal bypass • Mesorenal bypass

39. Surgical Revascularization Ex-vivo reconstruction To be considered in: Solitary kidney Complex renal artery branch reconstructions Options for Intervention

40. Options for Intervention • Percutaneous Treatment • Renal artery angioplasty • Renal artery angioplasty with provisional/selective stenting • Renal artery stenting

41. No controlled studies comparing angioplasty vs. stenting • Limited data comparing angioplasty/stenting to surgical revascularization • No strong evidence demonstrating superiority of surgical revascularization over medical therapy • No strong evidence demonstrating superiority of renal angioplasty/stenting over medical therapy • Uncontrolled, non-randomized data supports the use of renal revascularization in high-risk groups

42. Side-by-side comparison of large surgical series and renal angioplasty series suggests better durability and improvements in renal insufficiency in surgical patients • Comes at the cost of higher peri-procedural morbidity and mortality • So percutaneous treatments selected in most patients other than those with need for aortic reconstruction or with contraindications for PTA

43. Randomized Trials Percutaneous Renal Artery Intervention

45. EMMA Trial, 1998 • Unilateral atherosclerotic RAS • Normal renal function • 59 patients randomized • Primary outcomes • Ambulatory blood pressure (ABP) • Secondary outcomes • Treatment score • Complications

46. No difference in ABP • But lower Treatment Score (fewer meds) in angioplasty group • Higher procedural complication in angioplasty group (26% vs. 8%) • Criticisms: • 1/3 eligible screened patients not enrolled because of patient or physician preference for angioplasty • Protocol called for antihypertensives in angioplasty group if BP control ‘not optimal’ • Study design biased to not demonstrate primary outcome

48. Scottish/Newcastle study, 1998 • Atherosclerotic uni- or bilat- RAS • 135 patients eligible • Only 54 randomized • Non-randomized patients included for analysis • Primary endpoints • Mean BP and serum creatinine • 4 weeks and 6 months

49. Mean BP improved in medical and intervention arms during study period • Mean BP after angioplasty improved only in the bilateral, randomized group • Reduced hypertensive medication usage from 2.8 to 2.3 drugs in angioplasty groups • No differences in renal function between groups