Expandable medical devices

A medical device comprising:

• an elongated tubular body having proximal and distal ends;
• an expandable element at the distal end of the elongated tubular body, the expandable element being configured to exert a first expansion pressure and a second expansion pressure that is greater than the first expansion pressure;
• and
• an expandable tubular sleeve including a first end region, a second end region, and a middle region disposed between the first and second end regions, the expandable tubular sleeve disposed about the expandable element such that the expandable tubular sleeve can be fully expanded and retracted in association with the expandable element, the first end region having an amount of longitudinal compression that defines a first compression ratio and the middle region having an amount of longitudinal compression that defines a second compression ratio that is less than the first compression ratio such that first and second compression ratios of the expandable tubular sleeve alone are sufficient to dictate a sequence of expansion of the expandable element that includes the middle region expanding first in response to applying the first expansion pressure and the first end region expanding subsequently in response to applying the second expansion pressure greater than the first expansion pressure.

A medical device, comprising:

• an elongated tubular body having proximal and distal ends;
• an expandable element at the distal end of the elongated tubular body, the expandable element being configured to be activated to outwardly exert expansion pressure;
• and
• an expandable tubular sleeve disposed about the expandable element such that the expandable tubular sleeve can be fully expanded and retracted in association with the expandable element, the expandable tubular sleeve comprising at least a first end portion, a second end portion, and a middle portion between the first and second end portions, the middle portion having a radial strength less than a radial strength of the first end portion and less than a radial strength of the second end portion, the radial strength of the first end portion being defined by a compression ratio of the first end portion, the radial strength of the second end portion being defined by a compression ratio of the second end portion, and the radial strength of the middle portion being defined by a compression ratio of the middle portion of the expandable element, the middle element having a lower compression ratio than the first and second end portions such that first and second compression ratios of the expandable tubular sleeve alone are sufficient to dictate a sequence of expansion of the expandable tubular sleeve according to which the middle portion expands first in response to applying a lower expansion pressure and the first or second end portion expands subsequently to the middle portion in response to applying a higher expansion pressure.