Speak with your physician regarding long-haul air travel. If you are experiencing swelling at ground level, the results at high altitude can present a significant medical risk.
If you are cleared, be careful about what you say to any air carrier employee. Especially for long-haul, they are trained to seek medical assurances ---- usually through their own in-house or contracted medical service ---- that you are "fit to fly." A medical diversion on a long-haul flight may be dangerous or not possible.