House has had two near-death experiences at the time of this episode. The first (that we know of) was when he had a heart attack during his treatment for the infarction ("Three Stories"). During the time he was hovering between life and death, he seemed to have an out of body experience, or so he told his class, dropping in on the futures of three patients, whom he may or may not have ever treated. These patients all had leg issues and their treatments had differing outcomes than his (both for the better).
When asked about these experiences - these visions - House says that the “white light” that some people seem to see when having a near-death experience (and the visits to the afterlife) are merely the chemical effects of the brain shutting down. It’s what, he says, he chooses to believe. He explains that his choice to believe this makes him more comfortable. His disbelief in the afterlife makes him hopeful that life (as brutal as it’s been at times, we now know) is not simply “a test” for some other life to come.
House’s second near-death experience came when he was shot by an assailant who has not, to this day, been caught. The loss of blood and shock had him hovering between life and death as he hallucinated entire conversations with his shooter. During his hallucination, House assessed his own life and self-worth in conversations with the shooter (who, because it was a hallucination, was really his own subconscious). Ultimately confronted with the easy exit of death (symbolized by the scene where he shared the suicide attempt of the shooter’s wife), House chose life and fought his way out of unconsciousness, however briefly, to tell Cameron he wanted to try a radical pain-management treatment. If he was going to live, he was going to try to better his conditions.
Arguably, House has had (at least) one attempted suicide — arguably, because there is some debate as to whether taking a bottle-full of oxycodone and forcing himself to drink a large tumbler full of whiskey is attempted suicide. And arguably because we don’t know if he’s been in a state where, perhaps just after the infarction or when Stacy left him, he was suicidal. Wilson says that House fell apart, so it’s possible.
So, what do we make of what happened in “97 Seconds?” We haven’t seen House in physical pain much this season; he seems, physically anyway, to be coping fairly well. We’ve seen him take Vicodin, but not hiding his pain; not wincing, not hurting, which have been past signals that House is not doing well physically. The only noteworthy occasion in "97 Seconds" when we see him in physical distress is after he distributes the patient charts to his candidates, coming down the lecture hall stairs without his cane. As he hobbles to the desk and perches on it, he is in quite a bit of pain. But I don’t think it’s significant to the story.