Fig. 1

Angiography and intravascular ultrasound (IVUS) of the treatment with the fracking technique in case 1. A Control angiography for quantitative vessel analysis (QVA) showed stenosis of 94% in eccentric calcified plaque in the right common femoral artery (green arrow), and IVUS before treatment showed a minimal lumen area (MLA) of 6.2-mm². B After dilatation with a 6.0 × 20-mm cutting balloon, QVA showed 24% stenosis (yellow arrow), and the MLA was 10.7-mm². C After a 7.0 × 40-mm noncompliant balloon inflation and percutaneous direct needle puncture of calcified plaque (PIERCE) to modify the calcification (Ichihashi et al. 2014), the MLA was 17.1-mm². D After the fracking was repeated at three locations at up to 8-atm, QVA showed an improvement of stenosis to 16% (blue arrow), and the MLA was significantly much greater, to 27.1-mm²