[sanotehu]

Yes, they are indeed. As a medical student I had the privilege of seeing a heart valve being installed. They are a witness to how far medicine has progressed since the days of barber surgeons.

The blood is taken out of your body through the femoral vein (under the skin between your hip and your nether regions), taken through the perfusion machine and pumped back into the femoral artery. Because at this stage the heart will have been stopped, the high pressure in the femoral artery makes blood flow backwards up the aorta, where it supplies oxygenated blood from the machine to the whole body.

At one stage the flow has to be switched off in order to sew the metal valve onto the top of the aorta. In preparation for this, the blood leaving the perfusion machine is chilled (I'm not sure to what temperature). This slows the body's metabolism down and would cause hypothermic stupor if the patient had not already been under anaesthetic. I was told by the perfusionist that this gave the surgeons around an hour of extra operating time before the brain's oxygen content dropped to dangerous levels. All this is of course monitored by the anaesthetist and the perfusionist. The hypothermia will be reversed during the process of reviving the patient.

With the advent of endovascular procedures, this sort of surgery is becoming a rarity. It's much easier to pass a small tube up the aorta and inflate the narrowed artery from the inside than it is to open up the chest and sew a new blood vessel onto the heart. Of course, the medicine's more boring but it's all about getting a good outcome for the patient, isn't it?

[gonzo]

As a medical student you'll appreciate that I have a 3-4" stint replacing a section of my aorta, starting about 1mm away from the aortic root.

This to repair an ascending aortic dissection that terminates in my left iliac.

I walked out of the hospital, but the recovery was a PITA.

My core temp got down to 18C (65-66F) for over an hour. (According to the surgical notes I was on the heart lung machine for over 4 hours, and without perfusion for 45 minutes.)

[sanotehu]

I think it's a testament to modern medicine that we can do these sorts of things. Glad to hear you got through the recovery alright. With the operation I saw, they packed the patient's head with ice bags as well as cooling the blood. I remember thinking to myself that I'd hate to be that guy waking up! Something like a large hangover ;)

[gonzo]

Oh yeah, 20 years ago and I'd have never survived the night.

Whole thing is here, http://aorticdissection.com/2011/12/06/jim-thompson-47/ though I assumed that the termination was the right iliac until last Spring, when I had them run a CT on the lower extremities, and found that the termination was in my left leg (and that the false lumen had blocked the iliac in my right leg.)

Maybe when you're a doctor you'll remember, "When the symptoms don't make sense, think dissection" and save someone else.

[shaydoc]

Amazing, the knowledge acquired, distilled and shared to enable this is just wanted immense. My father had a major bypass op 6 years ago and I remember him saying how he felt when he first awoke after the surgery. He mentioned feeling cold!

[UnFleshedOne]

I felt very cold waking up after surgery for lung collapse (as in, shivering uncontrollably, not really hypothermic I guess). I don't think they specifically lowered my temperature. Maybe that is a common effect of general anesthesia?

Those heated blankets they have in post-surgery rooms are very nice...

[sanotehu]

Shivering is a common side-effect of general anaesthetic. I've not seen enough post-op recovery to know exactly how common, but it's high on the list of side-effects we have to tell people.

WRT the hypothermia, you may have been slightly hypothermic as a result of having so much of your body surface exposed to the air. People don't realise that ambient temperature (18-22C) is actually quite cold in relation to body temperature (36.7C) - it's only the fact that we wear clothes that means we don't feel it.

Nowadays we have heated blankets in theatre too, to offset this heat loss.