Conductance sizing balloon for measurement of peripheral artery minimal stent area

BackgroundBecause stent underdeployment occurs frequently, accurate minimal stent area (MSA) measurement during postdilatation is necessary. This study investigated the accuracy and repeatability for MSA determination using a novel conductance balloon (CB) catheter for peripheral vessels.MethodsThe CB catheter is a standard balloon catheter that measures electrical conductance (ratio of current/voltage drop) in real-time during inflation, which directly relates to the balloon cross-sectional area through Ohm's law. CB measurements were made in 4- to 10-mm phantoms on the bench, ex vivo in stents fully deployed in diseased human peripheral arteries, and in vivo in stents fully deployed in peripheral vessels in six swine. CB measurement accuracy and repeatability were calculated and compared with the known dimension (bench phantoms) or with intravascular ultrasound (IVUS) measurement after stent deployment (ex vivo and in vivo).ResultsCB measurements were highly accurate (error: 1.8% bench, 5% ex vivo, and 5% in vivo) and repeatable (error: 0.9% bench, 1.8% ex vivo, and 1.3% in vivo), with virtually no bias (average difference in measurements: −0.05 mm bench CB vs known phantom diameters, −0.06 mm ex vivo CB vs IVUS, and −0.11 mm in vivo CB vs IVUS).ConclusionsThe CB sizing capability can be integrated within a standard balloon catheter (two-in-one function) to provide accurate, real-time assessment of MSA to ensure full stent apposition rather than the use of pressure as a surrogate for size.

Clinical RelevanceClinically, stent underdeployment is likely given that the expected balloon dimension is often not reached in vivo (ie, pressure/diameter relationships supplied by the manufacturer are inaccurate in vivo). The conductance balloon device described here serves as a standard postdilatation balloon with additional real-time, accurate, dimensional feedback. Balloon usage could eliminate the need for multiple inflations and potentially help with complications related to balloon underinflation and stent recoil, including in-stent restenosis, stent thrombosis, and revascularization. The future use of the technology could expand beyond peripheral postdilatation to other balloon applications, including coronary postdilatation, drug-eluting, cutting, cryoplasty, and valvuloplasty balloons.