A balloon catheter device includes a multifilar tube shaft having a shaft lumen. A shaft lumen coating is provided on a surface of the multifilar tube shaft and extends from a proximal end of the multifilar tube shaft and terminates before a distal end of the multifilar tube shaft. An inflation balloon is disposed at the distal end of the multifilar tube shaft such that the shaft lumen coating and the inflation balloon form a continuously sealed length of the shaft lumen. The shaft lumen defines an inflation lumen that is in fluid communication with an interior space of the inflation balloon.