The invention relates to a device and method for approximating two vessels. The device includes a first catheter and a second catheter. The second catheter is slidably disposed in the first catheter. A first expansible member is disposed on the first catheter, and a second expansible member is disposed on the second catheter. The medical device also includes a locking mechanism for interlocking the first catheter and second catheter to prevent relative movement between the first and second catheters.