Dear wofahulicodoc: A spelling bee word was "coarct". Couldn't find it, so I looked for
"coarctation". To my surprise, medical meaning was not given"
1) coarctation. The American HeritageŽ Dictionary of the English Language: Fourth Edition.
2000.
...The state of being enclosed in an oval horny case. Used of an insect pupa

Now to look up "coarctation of the aorta".
Mirabile dictu, I found a radiograph, type not stated, showing narrowing where ascending
aorta becomes the descending aorta, just below the arrowhead. Used to be hopeless, now
can be surgically corrected. Marvelous.

http://info.med.yale.edu/intmed/cardio/chd/e_coarct/.