Combined large and small bore syringe

Claim 1

In combination, a dilatation catheter comprising a catheter portion and a syringe portion having its distal outlet end attached to the proximal inlet end of the catheter portion, said catheter portion comprising an elongated flexible tube having an invertible-eversible balloon element attached to and received within the distal end thereof, said syringe portion comprising a large bore cylinder and a large bore piston fitted therein and a small bore cylinder and a small bore piston fitted therein, said large bore cylinder having a distal outlet end in communication with said flexible tube, said large bore piston having said small bore cylinder formed therein, said small bore cylinder having a distal outlet end in communication with said large bore cylinder, the cross-sectional area of the bore of said large bore cylinder being a plurality of times as great as the cross-sectional area of the bore of said small bore cylinder whereby compression of said small bore piston within said small bore cylinder functions to evert the balloon element under high pressure and compression of said large bore piston within said large bore cylinder functions to inflate the balloon element under a lower pressure for dilatation.

Claim 6

A method of everting and inflating an invertible-eversible balloon element of a dilatation catheter comprising the following steps: providing a syringe which includes a large bore cylinder and a large bore piston fitted therein, with said large bore cylinder having a distal outlet, and a small bore cylinder with a small bore piston fitted therein and having a distal outlet in communication with said large bore cylinder, said large bore piston having said small bore cylinder formed therein; coupling said distal outlet of said large bore cylinder to an inlet of the dilating catheter; disposing a fluid in the catheter and in said large and small bore cylinders of said syringe; forcing said small bore piston into said small bore cylinder so as to cause a first volume of said fluid to be delivered to the catheter at a relatively high fluid pressure to evert the balloon element; and forcing said large bore piston into said large bore cylinder so as to cause a second volume of said fluid to be delivered to the catheter at a relatively low fluid pressure to inflate the balloon for dilata-purposes.

Claim 7

A method of everting and inflating an invertible-eversible balloon element of a dilatation catheter comprising the following steps: providing a syringe which includes a large bore cylinder and a large bore piston fitted therein, with said large bore cylinder having a distal outlet, and a small bore cylinder with a small bore piston fitted therein and having a distal outlet in communication with said large bore cylinder, said large bore piston having said small bore cylinder formed therein; coupling said distal outlet of said large bore cylinder to an inlet of the dilating catheter; disposing a fluid in the catheter and in said large and small bore cylinders of said syringe; forcing said small bore piston into said small bore cylinder so as to cause a first volume of said fluid to be delivered to the catheter at a relatively high fluid pressure to evert the balloon element; and forcing said large bore piston into said large bore cylinder so as to cause a second volume of said fluid to be delivered to the catheter at a relatively low fluid pressure to inflate the balloon for dilata-purposes.