Cholesterol embolism evaluated by polarized light microscopy after primary renal artery stent placement with filter...

Cholesterol microembolization may explain some treatment failures after renal artery stent placement. The identification of cholesterol crystals may provide significant help in diagnosing the real frequency and severity of this complication. The aim of the present study was to examine the efficacy of polarized light imaging in the detection of cholesterol emboli trapped in a protection device.

During a period of 18 months, 15 significant atherosclerotic stenoses of the ostium of the main renal artery were treated with primary stent placement with embolic protection. The filter device used was made of polyurethane, with a pore size of 115 ?m. The device was mounted over a 0.014-inch guide wire. For pathologic analysis, the recaptured filter basket was compressed between two slides and examined in a microscope under polarized light.

All the stenoses were successfully treated without clinical complications. All the filters were deployed and recaptured without difficulty. Cholesterol crystals were detected in 12 filters and no cholesterol was found in three. In one case, trouble with filter manipulation precluded pathologic analysis. No worsening of renal function was detected in any patient during follow-up.

Microscopic analysis with polarized light easily detects the cholesterol crystals trapped in the filter device. This provides evidence that renal cholesterol microembolism is highly prevalent during renal artery stent placement.