The coaxial, double-lumen catheter has a 12F polyvinyl chloride tube shaft (Figure 1).

Figure 1
       The inner lumen of the catheter permits pressure measurements, blood sampling or insertion of a metal tube, a guide wire, or a stylet (Figure 2, A). The outer lumen connects proximally with a two-way stopcock (B) (used to connect the catheter to an inflation/deflation syringe), and a vent (C). The balloon, made of double layers of latex tubing, is mounted at the distal end of the catheter shaft.

Figure 2

       There are four types of balloon catheters, each designated by a symbol followed by its maximally inflatable balloon diameter (in mm): PTMC-30, PTMC-28, PTMC-26, and PTMC-24. The second-generation catheter balloons now in use (manufactured after September 1989) are less compliant and thus more pressure resistant than the first-generation ones. Please refer to the "Pressure-Volume Relationship" chart under PTMC Procedures -- Controlled Stepwise Dilatation Technique.

       The balloon can be transformed to various shapes from its natural form (Figure 3) to serve different functions. The balloon segment stiffens and slenderizes when the latex balloon is stretched by inserting a metal tube (A). The slenderized balloon allows a smooth entry of the balloon catheter into the femoral vein without the use of an introducer set. It also permits an easy passage of the catheter across the atrial septum after the septum has been dilated with a dilator.

       The synthetic mesh of the balloon is wound in such a way that the balloon changes shapes from its natural form (B) in three stages, depending on the extent of inflation. Initially, only the distal half inflates (C); then the proximal half inflates (D), with a constriction remaining in the middle. Finally, at full inflation, the constriction disappears (E) and the balloon assumes a more barrel-like shape with a maximal length of 45 mm. The entire inflation/deflation cycle takes about 5 seconds.

Figure 3
Versatility of the Inoue Balloon Catheter
 
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© 2002-2004 Dr. Jui-Sung Hung. All Rights Reserved.
Questions or Comments? Email shung@pipeline.com.