Margret had a few episodes of fainting, five that I know of, over a period of several years. Here's how I reasoned one day in the late 1980s that she had pulmonary hypertension:
Margret had just completed a riding lesson, and had done well. She was now standing, holding the horse's head, while her teacher picked out his feet.* Her lips became very blue, and she fell over. Fortunately she still had on her hard hat to protect her head. She was limp, her skin was bluish, and she didn't respond to my voice nor her teacher's nor to being shaken.
While this was going on, some analytical part of my mind said, "She was just riding, so there was a greater demand for blood in her body, and her capillaries are now dilated. That lessens resistance to blood flow out through the aorta. With the hole in her heart, lessened left side resistance encourages the blood to go that way, through the hole from right to left, and not off to her lungs to pick up needed oxygen. So. Cyanosis. And a faint. That means the resistance to blood flow in her lungs is high, needing higher pressures to push blood through, hence pulmonary hypertension."
She revived on her own after a very short time. She appeared quite normal after, but was excruciatingly embarrassed that she'd wet herself. We went home, mentioned the incident to the doctor, saw the cardiologist, and life went on.
When I explained my reasoning to her cardiologist, he nodded absently and moved on to something else. I wasn't sure if he blew me off, or if he simply didn't think this fainting business was important, but that's as far as it went. We did not get a proper diagnosis for years.
Wish I knew then what I know now. He would have got an earful, and we might have changed specialists. I would have done a number of things differently. But I didn't know. I don't think there were many people at that time, medical or lay, who knew.
Hindsight. Isn't it wonderful? and terrible? and generally useless in the now except to make you feel bad.
I did the best I could with the information I had. I just didn't have enough information to do the things that might have slowed her PH down. Back then, the phrase 'pulmonary hypertension' was just a description of something I had worked out with logic, not a diagnosis, not worthy of capital P and H.
*Students usually picked out the horse's feet on their own, but Margret had knee problems. The amount of difficulty she experienced, and fear of an accident, exempted her from doing feet, but she had to participate by holding the horse still.