Endovascular device with internally-fixed balloon

1. An endovascular apparatus, comprising:

an elongated catheter having an inner lumen extending therethrough;

a balloon affixed to the catheter for expansion into the inner lumen of the catheter when the balloon is inflated;

a tube secured relative to the balloon, wherein the tube is configured to enable selective inflation and deflation of the balloon; and

at least one electrode located at the same axial position along the catheter as the balloon, wherein upon inflation of the balloon, the balloon is configured to press a medical instrument within the inner lumen of the catheter against the at least one electrode, and

wherein an outer diameter of a portion of the catheter adjacent the balloon is substantially the same when the balloon is inflated and when the balloon is deflated.

2. The endovascular apparatus of claim 1 , wherein the balloon is situated in an opening formed in a side wall of the catheter.

3. The endovascular apparatus of claim 2 , wherein the balloon is configured to expand through the opening and into the inner lumen of the catheter when the balloon is inflated.

4. The endovascular apparatus of claim 1 , wherein the balloon is situated outside of the inner lumen of the catheter when the balloon is deflated.

5. The endovascular apparatus of claim 1 , wherein an internal volume of the portion of the catheter adjacent the balloon is smaller when the balloon is inflated than when the balloon is deflated.

6. The endovascular apparatus of claim 1 , wherein an internal shape of the catheter adjacent the balloon is substantially circular when the balloon is deflated and non-circular when the balloon is inflated.

7. The endovascular apparatus of claim 1 , wherein the tube is arranged over the catheter, with an inflation passage formed between an outer surface of the catheter and an inner surface of the tube for delivery of inflation fluid to the balloon.

8. The endovascular apparatus of claim 7 , further comprising an airtight seal on an opposite side of the balloon from the inflation passage, wherein the airtight seal is configured to secure the catheter and the tube against relative movement.

9. The endovascular apparatus of claim 8 , wherein the airtight seal includes an inner surface delimiting an interior volume contiguous with the inner lumen of the catheter, and wherein the inner lumen of the catheter and the interior volume of the airtight seal form a delivery channel for advancement of the medical instrument therethrough.

10. The endovascular apparatus of claim 1 , wherein the balloon is configured to be selectively inflated and deflated based on control signals from a control device positioned outside a body of a patient.

11. The endovascular apparatus of claim 1 , further comprising at least one additional balloon affixed to the catheter for expansion into the inner lumen of the catheter when the at least one additional balloon is inflated.

12. The endovascular apparatus of claim 1 , wherein the balloon is configured to exert a stronger friction force on the medical instrument when the balloon is inflated, compared to when the balloon is deflated.

13. The endovascular apparatus of claim 1 , wherein the balloon is configured to obstruct axial advancement of the medical instrument through the inner lumen of the catheter when the balloon is inflated.

14. The endovascular apparatus of claim 1 , wherein upon inflation, the balloon is configured to secure the medical instrument against axial movement.

15. The endovascular apparatus of claim 1 , wherein an axial distance between the balloon and a distal tip of the catheter is equal to one inch or less.