As far as the flights, all of them (United-I know) have great medical kits, trained flight attendants who will request medical professionals but can administer help to a degree. Cockpit access to 24/7 doctors who help make calls in what to do to help the passenger, diverting, continuing to destination etc. luckily for her the time this occurred was close to LAX and the crew got there as quick as possible and had medical staff waiting and immediately on the plane when they arrived. They got the best case scenario for her and heopefully she recovers completely.

if you are traveling a lot or on long distance flights I would highly encourage you to get up and take a walk through the cabin, stretch your legs and arms, get some blood flowing and as long as it's okay for you health wise, take a baby aspirin. That advice saved the life of one of my Flight attendants earlier this year on a long haul flight.