Vascular dilatation device and method

DETAILED DESCRIPTION I claim: 1.
A vascular dilatation device for enlarging a flow passage in an obstruction in a vessel carrying flowing blood comprising a flexible cylindrical dilatation member for placement in the flow passage in the obstruction and having first and second ends and an intermediate portion between the first and second ends, said flexible cylindrical dilatation member also having an interior flow passage extending therethrough with a diameter and a longitudinally extending central axis, said diameter of said flow passage being variable with movement of the first and second ends relative to each other along the longitudinally extending central axis from a contracted position to an expanded position, said expanded position permitting blood to flow through the flexible cylindrical dilatation member and means for causing relative axial movement of said first and second ends towards each other from an extended position to a contracted position, said means for causing relative axial movement including an outer flexible elongate tubular member having proximal and distal extremities, said distal extremity of the outer flexible elongate tubular member being secured to the first end of said flexible cylindrical dilatation member and an inner flexible elongate tubular member having proximal and distal extremities and disposed between the first and second ends of the flexible cylindrical dilatation member, said distal extremity of the inner flexible elongate tubular member being secured to the second end of said flexible cylindrical dilatation member, said inner flexible elongate tubular member having sufficient rigidity for causing elongation of the cylindrical dilatation member so as to decrease its diameter and cause advancement of the cylindrical dilatation member through the obstruction in the vessel while preventing axial contraction of the cylindrical dilatation member.
2.
A device as in claim 1 further including a coil spring carried by said inner flexible elongate tubular member, said coil spring having turns which are in apposition to each other