A catheter for carotid artery dilatation that includes a multi-chamber balloon assembly mounted at the distal end of the elongated tube that has at least two tandem chambers. Each side wall has an open slot extending from the edge to a closed end or base. The clip also biases the release button to a retracted position, the release button being in the retracted position when the cutting head is in the operating position. The bitlines are connected to the sourcedrain regions.