Fig. 2

Angiography and intravascular ultrasound (IVUS) of the treatment with the fracking technique in case 2. A Control angiography for quantitative vessel analysis (QVA) showed eccentric calcified plaque in the distal common femoral artery with stenosis of 96% (green arrow), and IVUS before treatment showed a minimal lumen area (MLA) of 10.0-mm². B After balloon dilatation with a 7.0 × 40-mm noncompliant balloon, QVA showed 42% stenosis (yellow arrow), and the MLA was 13.1-mm². C After the 7.0 × 40-mm noncompliant balloon inflation and percutaneous direct needle puncture of calcified plaque (PIERCE) (Ichihashi et al. 2014), the MLA was unsatisfactory, at 15.9-mm². D After the fracking technique was repeated at two locations at up to 5-atm, QVA showed an improvement in stenosis to 26% (blue arrow), and the MLA was significantly greater, at 28.9-mm²