Timir Paul, MD, PhD, FSCAI; Hady Lichaa, MD, FSCAI; Konstantinos Dean Boudoulas, MD, FSCAI

Introduction

Approximately 6.8% of healthy adults aged >65 years have renal artery stenosis (RAS) with a higher prevalence among those with cardiovascular (CV) risk factors, which is a marker of poorer prognosis.¹ It is estimated that ~10% of hypertensive patients in the US have resistant hypertension, and RAS is a common secondary cause (5%-34%).² The CORAL trial demonstrated that renal artery stenting is not associated with improvement of major adverse CV events³; however, for certain indications, as described in this Tip of the Month (TOTM), renal intervention remains an important therapeutic option. In addition, this TOTM will discuss some practical tips for renal artery intervention.

Table 1: ACC/AHA Guidelines on Screening, Diagnostic Modalities, and Treatment/ Revascularization of RAS^4,5

ACC: American College of Cardiology; AHA: American Heart Association; ACEIs: angiotensin-converting enzyme inhibitors; ARBs: angiotensin receptor blockers; MRA: magnetic resonance angiography; CT: computed tomography

Patient Selection

Appropriate patient selection is the key for optimal clinical outcomes of renal artery revascularization. Treating hemodynamically insignificant lesions, symptoms not related to RAS, and the concomitant presence of renal parenchymal disease are predictors of poor outcomes.

Table 2: Hemodynamic Criteria for Significant RAS and Predictors of Advanced Nephropathy

IVUS: intravascular ultrasound; Pd/Pa: ratio of mean distal to lesion to proximal pressure; FFR: fractional flow reserve; RRI: renal resistive index

Procedural Tips and Tricks

• Access:
  • A 6F to 7F femoral sheath depending on the selected stent size and type (uncovered vs. covered)
  • A 5F/6F or 6F/7F thin-walled radial sheath as a good alternative (left vs. right radial depending on the patient’s height, innominate artery tortuosity, and aortic arch type)
• Guide catheter:
  • Femoral:
    • A 65 cm 6F or 7F guide with a curved tip (i.e., Internal Mammary [IM], Renal Double Curve [RDC], Hockey Stick)
    • Other options: 6F to 7F sheathless guides to minimize the femoral arteriotomy size; 7F deflectable tip sheaths mostly for the use of a covered stent
  • Radial: A 100 cm to 125 cm main pulmonary artery (MPA) or Judkins right (JR)4 guide depending on the patient’s height, left vs. right access, and renal artery takeoff
• IVUS: Improvement of procedural safety, the lesion preparation strategy, the choice of stent type/size, and the post-dilation decision⁶
• Carbon dioxide (CO₂) gas: Very helpful in the avoidance of iodinated contrast use, especially when combined with IVUS⁷
• Renal FFR: Any 0.014” pressure wire for use in measuring renal FFR with papaverine or dopamine, with <80 being significant⁸
• Embolization-prevention techniques: Utilization of techniques such as guide catheter telescoping using a diagnostic catheter or the no-touch technique
• Balloon (definitive therapy for renal FMD):
  • Femoral:
    • 014” compatible semi-compliant or noncompliant balloons
    • Off-label use of cutting and scoring balloons or intravascular lithotripsy, which may be useful depending on lesion morphology
    • Availability of a dedicated ostial flaring balloon, if needed
    • No data on drug-coated balloons
  • Radial:
    • A 12 mm-20 mm 0.014” compatible 145 cm-155 cm monorail shaft (compliant or noncompliant)
    • Use of a short hemostatic valve (i.e., Checkflo [Cook Medical]), which allows reach in non-ostial lesions
  • Stent:
    • Femoral:
      • A 0.014” compatible balloon-expandable, bare-metal stent
      • Off-label use of dedicated coronary thick-strutted, left main drug-eluting stents (i.e., Megatron [Boston Scientific])
    • Radial:
      • A 0.014” compatible 135 cm-150 cm monorail shaft, balloon-expandable bare-metal stent
      • Off-label use of 145 cm monorail shaft coronary drug-eluting stent or coronary-covered bare-metal stent

Conclusion

Screening for RAS should be performed as per current ACC/AHA guidelines for aggressive risk factor modification and optimal medical therapy. For patients with severe RAS, who have uncontrolled hypertension on ≥ 3 medications — including a diuretic — or are intolerant to medications, renal artery stenting remains an important option.

References

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2. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018 Jun;71(6): 1269-1324.
3. Cooper CJ, Murphy TP, Cutlip DE, et al. Stenting and medical therapy for atherosclerotic renal-artery stenosis. N Engl J Med. 2014 Jan 2;370(1):13-22.
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8. Subramanian R, White CJ, Rosenfield K, et al. Renal fractional flow reserve: a hemodynamic evaluation of moderate renal artery stenoses. Catheter Cardiovasc Interv. 2005 Apr;64(4):480-6.