Assessment of computer-controlled inflation/deflation for determining the properties of PTCA balloon catheters with pressure-volume curves.
Restenosis is a significant problem after percutaneous transluminal coronary angioplasty (PTCA), leading to further angina or even death. The mechanisms causing restenosis are not well understood and the effect of the angioplasty balloon on the artery wall is generally unknown. The aim of the research presented here was to assess the repeatability with which measurements of balloon pressure-volume characteristics could be made, to ensure that different balloons could be distinguished easily, an essential first step before the arteries themselves could be characterized. An inflation/deflation device was inflated with and without an attached balloon under computer control at a constant speed to 8 bar. The accuracy and repeatability of the technique was assessed within a single measurement session and between measurement sessions on six separate days. For each measurement session, four repeated inflations/deflations were carried out and the average was determined. Compliance (volume change/pressure change), inflation volume and pressure drop at 8 bar were determined for various balloon catheters of different size, type and manufacturer. The system repeatability SD for measuring volume without a balloon was +/- 0.0005 ml within a single measurement session, and +/- 0.002 ml between independent days. With an attached balloon the repeatability SD for measuring volume was +/- 0.001 ml within, and +/- 0.003 ml between days. Compliance was determined with a repeatability SD of +/- 0.16 microliter bar-1 within, and +/- 0.94 microliter bar-1 between days. The inflation/deflation device and technique employed allowed small changes in volume and compliance to be differentiated. The system also enabled differences due to the material characteristics for different PTCA balloons to be determined. Measured balloon characteristics were similar to the data given by manufacturers. This gives confidence in development of the technique for clinical use.
Olbrich
T
T
Regional Medical Physics Department, Freeman Hospital, Newcastle-upon-Tyne NE7 7DN, UK. tom.olbrich@nuth.northy.nhs.uk
Murray
A
A
D000399:Air Pressure; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation*; D002404:Catheterization / Q000295:instrumentation*; D003201:Computers; D006801:Humans; D015203:Reproducibility of Results; D013696:Temperature