Pleated or folded catheter-mounted balloon

1. A catheter-mounted balloon comprising:

an inflatable chamber defining a volume expandable from a deflated state to an inflated state, the inflatable chamber having a distal transition portion, a proximal transition portion, and a cylindrical body portion disposed between the distal transition portion and the proximal transition portion,

wherein the cylindrical body portion includes at least first and second pleat zones each having a soft pleat that causes the inflatable chamber to collapse or fold along the soft pleat into a pre-determined pleat pattern when the inflatable chamber is pushed through or pulled back into a guide catheter, wherein at least a portion of each soft pleat extends along a longitudinal axis of the cylindrical body portion when the inflatable chamber is in the deflated state, and wherein each soft pleat extends at least partially into the proximal transition portion of the inflatable chamber;

wherein the proximal transition portion includes a transition portion pleat disposed between the soft pleats of the first and second pleat zones, wherein the transition portion pleat extends between proximal and distal ends of the proximal transition portion substantially free of extension into the cylindrical body portion; and

an electrode disposed along a wall of the inflatable chamber, wherein at least one of the soft pleats traverses the electrode such that the electrode is pleated.

2. The catheter-mounted balloon of claim 1 , wherein the inflatable chamber defines at least one irrigation aperture to allow fluid to flow from within the inflatable chamber to outside the inflatable chamber when the inflatable chamber is in the inflated state.

3. The catheter-mounted balloon of claim 2 , wherein the at least one irrigation aperture is at least partially unobstructed by the soft pleats when the inflatable chamber is in the deflated state.

4. The catheter-mounted balloon of claim 2 , wherein the at least one irrigation aperture is disposed between one of the soft pleats and a side of the electrode.

5. The catheter-mounted balloon of claim 1 , wherein the electrode is helical around a longitudinal axis of the inflatable chamber.

6. The catheter-mounted balloon of claim 1 , wherein the inflatable chamber is collapsible along the soft pleats in response to a decrease in the volume of the inflatable chamber as the inflatable chamber is deflated from the inflated state to the deflated state.

7. The catheter-mounted balloon of claim 1 , wherein the inflatable chamber comprises a layer of shape memory material.

8. The catheter-mounted balloon of claim 1 , wherein at least one of the distal transition portion or the proximal transition portion of the inflatable chamber is frustoconically shaped.

9. The catheter-mounted balloon of claim 1 , wherein the soft pleats have crinkled pleats configured to reduce a likelihood that electrical properties of the electrode are compromised by the soft pleats.

10. The catheter-mounted balloon of claim 7 , wherein the shape memory material comprises a shape-memory polymer.

11. A catheter comprising:

a balloon at a distal portion of the catheter and including:

an inflatable chamber defining a volume expandable from a deflated state to an inflated state, the inflatable chamber having a distal transition portion, a proximal transition portion, and a cylindrical body portion disposed between the distal transition portion and the proximal transition portion,

wherein the cylindrical body portion includes a pleat zone having soft pleats that causes the inflatable chamber to collapse or fold along the soft pleats into a pre-determined pleat pattern when the inflatable chamber is pushed through or pulled back into the catheter, wherein at least a portion of the soft pleats extend along a longitudinal axis of the cylindrical body portion when the inflatable chamber is in the deflated state, wherein the soft pleats extend at least partially into the proximal transition portion of the inflatable chamber;

wherein the proximal transition portion includes a transition portion pleat disposed between the soft pleats of the pleat zone, wherein the transition portion pleat extends between proximal and distal ends of the proximal transition portion substantially free of extension into the cylindrical body portion; and

an electrode disposed along a wall of the inflatable chamber, wherein the soft pleats flank both sides of the electrode,

wherein the balloon is configured for guidewire delivery to an intravascular treatment site within a blood vessel of a human patient while the inflatable chamber is in the deflated state, and

wherein, when the inflatable chamber is in the inflated state, the cylindrical body portion including the pleat zone has a consistent diameter between the proximal transition portion and the distal transition portion to position the electrode in contact with an inner wall of the blood vessel.

12. The catheter of claim 11 , wherein the inflatable chamber of the balloon comprises a layer of shape memory material.

13. The catheter of claim 11 , wherein the soft pleats have crinkled pleats configured to reduce a likelihood that electrical properties of the electrode are compromised by the soft pleats.

14. The catheter of claim 11 , wherein the electrode is helical around a longitudinal axis of the inflatable chamber.

15. The catheter of claim 11 , wherein the distal transition portion and the proximal transition portion of the inflatable chamber are frustoconically shaped.

16. The catheter of claim 15 , wherein the soft pleat extends at least partially into the frustoconically shaped distal transition portion of the inflatable.