According to an Emedicine Article on Hyperbaric Oxygen Therapy (http://www.emedicine.com/plastic/topic526.htm), cardiovascular effects of hyperbaric therapy are as follows:
Heart rate - Decreased
Contractility - No effect
Stoke volume - No effect
Cardiac output - Decreased
Blood pressure - Possible minimal increase
Systemic vascular resistance - After load increases, arterial vasoconstriction
Remember, obviously, a blood pressure cuff won't work underwater because you have to inflate it with air (but wouldn't it be neat if...nevermind) so the only data available is obtained from a chamber. But pressure is pressure. Any folks with chamber experience (working in it, preferrably, but sitting in it after a barometric misadventure will do too) are invited to jump in and clarify this with certainty.
I'm with MichaelBaranows though: Although this is strictly anecdotal, I think my blood pressure decreases at depth because I'm at peace.
Heart rate - Decreased
Contractility - No effect
Stoke volume - No effect
Cardiac output - Decreased
Blood pressure - Possible minimal increase
Systemic vascular resistance - After load increases, arterial vasoconstriction
Remember, obviously, a blood pressure cuff won't work underwater because you have to inflate it with air (but wouldn't it be neat if...nevermind) so the only data available is obtained from a chamber. But pressure is pressure. Any folks with chamber experience (working in it, preferrably, but sitting in it after a barometric misadventure will do too) are invited to jump in and clarify this with certainty.
I'm with MichaelBaranows though: Although this is strictly anecdotal, I think my blood pressure decreases at depth because I'm at peace.