On 6-7-2010 23:12, Orchid XP v8 wrote:
>>> At least I didn't say it was through the aorta. (That, of course, 
>>> would be the way *from* the heart, not *to* it.) I bothered to get 
>>> that much right. ;-)
>>
>> yes and no ;) Blood exits the heart via the aorta, but it used to be 
>> the standard entry point for catheters if you wanted to go to the left 
>> ventricle (where many arrhythmias originate).
> 
> Heh. I don't know if it's a rule of the Internet, but it probably should 
> be: For any conceivable topic, somebody else will know way, way more 
> about it than you. :-}

except that in this case you knew I would be such a somebody.

> 
> I would have thought trying to enter against the flow of blood through 
> the single largest blood vessel in the entire human body would be quite 
> difficult 

As you point out, it is big. Catheters are thin.

> - then again, I'm sure many people far more knowledgeable than 
> me have actually tried this out. Also, I guess it would depend on where 
> the hell you're trying to actually get to in the first place...
> 

>> BTW as you rightly guessed, that implies that the vast majority of 
>> catheterizations go via the inferior vene cava. Entering via the 
>> superior vene cava is very uncommon, except for the wires of a 
>> pacemaker or ICD (I guess you ended up in webpages describing those 
>> procedures).
> 
> Actually, I just looked up the major blood vessels of the heart and 
> tried to figure out which name goes with which tube on the diagram. 
> (You'd think this would be easy... you'd be wrong.) I eventually 
> determined that the two vena cavae are where the majority of blood 
> enters from, and arbitrarily selected the superior one.
> 
> Firstly because "superior" sounds better [although in fact I gather it 
> just means "higher up" in medical jargon], and partly because I imagined 
> the route from the brain to the heart. Most people perceive their body 
> looking down from where their head is. (Not that this has anything 
> remotely to do with the surgical feasibility of inserting stuff from 
> that direction...)

IIRC the first catheter insertion was via the arm, so that would have 
been the superior side. Aside, I think that you as a programmer would be 
more careful in selecting an apparently arbitrary choice of two. 
Especially if you know they are not interchangeable. Why didn't you go 
for e.g. the vena cava without mentioning wither inf. or sup.?

>> In principle you can also enter via the right outflow tract and there 
>> are also in general 4 lung venes (that transport oxygenated blood from 
>> the lungs to the left atrium). Of the top of my head I don't know of 
>> any procedure that uses any of those entry points.
> 
> Yeah, the heart is a double-pump, so there ought to be *two* entrances 
> in theory. (There are apparently more because humans have two lungs, 

with in most cases two venes entering from each lung (indeed an inferior 
and a superior).

> and because blood from above and below returns through different 
> routes.)
> 
> On a completely unrelated note, apparently in some animals the heart is 
> a single pump, and in yet others it's just a tube that sort of squirts,

In humans (and mammals and birds and probably also the reptiles and 
fishes) it starts out as a tube with peristaltic contractions only later 
the two separate circulations are formed. E.g. crocodiles have a single 
chamber, but don't make the assumption that therefore their heart is 
more primitive. For them that functions better than any 4 chambered 
heart would do.

Pity that given your interest in this topic (and in e.g. MathML) that 
you seem to be stuck in MK.

> and there are no blood "vessels" at all. The internal organs just sit in 
> a soup of... well, it's not even blood, it's haemolymph.
> 
> Then again, apparently some animals don't have red blood cells, the 
> haemoglobin just floats in solution. Larger animals don't do that 
> because to have enough haemoglobin to transport sufficient oxygen, their 
> blood would be like treacle. So RBCs evolved which are packed with this 
> oxygen-transport protein, but the blood remains liquid.
> 
> In other news, I spent a really absurd amount of time on Wikipedia. o_O

I think we noticed, and on WA.

>> To complete the picture you can also us a sternotomy or a laporoscopic 
>> procedure, but don't try that at home.
> 
> Yeah, that or any other medical procedure even remotely involving your 
> heart! o_O

I am not sure that sternotomy is 'remotely' involving hearts. I have 
been present at quite a number of procedures where this was the approach 
to open the heart and treat the inside.

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