#VitalsignsMOOC Week2 on Cardiac Stuff

This week flew by as the amount of new material was pretty limited. The quiz came out today, and I blew through it in about 5 minutes, getting a couple wrong because I didn’t read them properly. That being said, there is a huge boatload of information to reinforce from last week and a few cool rabbit trails.

I find that my knowledge of heart anatomy is still not at the point of being instantaneous. I’m having to look and think as to what the parts are, and thus more practice is needed. I did come across a most fascinating video from khan, where in they are viewing the heart from a patients perspective looking down into the chest. The interesting thing, albeit obvious point about this view is that it inverts the geometry left/right, in contrast with the anatomical view (coronal) I learned last week. I’m thinking multiple planes of view, both from the patient as well as the anatomical planes may prove beneficial as means of studying anatomy.

Being imaging studies reference the standard anatomical planes, I wonder if the observer (standard anatomical) vs patient reference frames might have played a role in the rapid prototype error discussed in the TED talk entitled how I repaired my own heart.

Hemodynamics has been bugging me to no end… and this graph is less than helpful.


The use of a linear Y axis completely buries pressure deltas starting with the capillairies and continuing on throughout the cardiac cycle. Alas, digging for a semi log plot of such to bring out the detail seems an exercise in frustration. One interesting bit to consider is the increased frequency in the arterioles, it appears to have doubled, but I’m not sure if that’s an artist error, or if muscle activity from the Tunica Media actually causes this.

Alas, the graph is helpful in one regard, as the first derivative clearly shows that aterioles are the major playing in decreasing pressure such that capillairies dont blow. This is graphical hand waving calculus… I’m not sure how you create a derivative with respect to a sequence of nouns. ­čÖé

That being said, I remember a post by @atdiy where she talked about a no beat heart, and some ideas as to why patient quality of life takes a header with a LVAD. Its a most fascinating read. See below for a xray of a no beat heart from healthcollege.edu.pl.

Getting back to a beating heart, I did find the following video of interesting. The author presents pressure variation where the supervior vena cava enters the atria. Its a rabbit trail for sure… but as I expected, there is massive variation in pressure (well massive from the point of view of heart action dicks around with the pressure) but not massive at all relative to the mean arterial pressure at the aorta.

Lastly, I managed to get a bee in my bonnet over what the professor said about mean aterial pressure referring to mean as an average… a moving average perhaps, but not an average of diastolic and systolic pressures. I did find an approximation formula which makes sense at https://www.columbia.edu/~kj3/Chapter3.htm .

Pm = 1/3Ps + 2/3Pd

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