Step I Ductus Arteriosus question

[zeloc]

From what I understand in the Goljan audio, the pulmonary artery mostly contains deoxygenated blood from the superior vena cava because the oxygenated blood from the umbilical vein through the inferior vena cava goes straight across the foramen ovale into the left atrium, and the blood from the SVC goes straight into pulmonary artery. But according to a question in mini-Qbook, the purpose of the ductus arteriosus is to shunt oxygenated blood from the pulmonary artery into the aorta. Which is it, or am I misunderstanding Goljan?

 

[xjacob]

From what I understand in the Goljan audio, the pulmonary artery mostly contains deoxygenated blood from the superior vena cava because the oxygenated blood from the umbilical vein through the inferior vena cava goes straight across the foramen ovale into the left atrium, and the blood from the SVC goes straight into pulmonary artery. But according to a question in mini-Qbook, the purpose of the ductus arteriosus is to shunt oxygenated blood from the pulmonary artery into the aorta. Which is it, or am I misunderstanding Goljan?

Yeah, I am always confused about this whole ductus thing. According to Moore, it carried blood with "medium oxygen content" in the fetus. The way I was taught at my school was that it is pretty much deoxygenated. Thus I think Kaplan is essentially wrong on this one.

 

[wwspeeds]

according to LANGE peds and surgery, they're both true.

The PDA shunts 60% of the total combined ventricular output into the aorta. The FO acts like a one way valve (sorta like a 5th heart valve) letting IVC blood directly into the L atrium.

Apparently goljan is a bad man but not a liar (in this case).

hope this is helpful

ww 😴

 

[zeloc]

So if it's 60% it's a good mixture of oxygenated and deoxygenated blood.

Another question: What is the best test for an acute MI? I'm guessing it's an ECG in the first 6 hours, but at 24 hours is it better to do CK-MB or troponins?

 

[exmike]

So if it's 60% it's a good mixture of oxygenated and deoxygenated blood.

Another question: What is the best test for an acute MI? I'm guessing it's an ECG in the first 6 hours, but at 24 hours is it better to do CK-MB or troponins?

troponin is more specific

 

[xjacob]

If I remember correctly, I was taught that troponins are "the best," but not yet done in all hospitals. CK-MB is thus more common.
As far as early diagnosis goes, ECG is always done, but it's snesitivity is not all the great. Troponins shoot up pretty soon after the MI, so they'd still be more sensitive. So it depends on what you mean by "best." Sensitivity -> troponin, Speed -> ECG.

 

[draino15]

from what i hear....the BEST test would be MYOGLOBIN.


however, i think its rarely used

 

[DropkickMurphy]

the BEST test would be MYOGLOBIN

Are you sure about this?

 

[draino15]

Barone said it for Kaplan PATH.

but....i guess it depends on how you define "BEST"

Myoglobin is the most SENSITIVE
but lacks SPECIFICITY
(it appears 1st, at about 2hours post-MI, peaks at 6-9hrs, and returns to normal at 24-36hrs.)

Troponin rises a tad later.
and i think is more SPECIFIC for the heart.

 

[xjacob]

Barone said it for Kaplan PATH.

but....i guess it depends on how you define "BEST"

Myoglobin is the most SENSITIVE
but lacks SPECIFICITY
(it appears 1st, at about 2hours post-MI, peaks at 6-9hrs, and returns to normal at 24-36hrs.)

Troponin rises a tad later.
and i think is more SPECIFIC for the heart.

yep, sorry, i meant to say that troponin is most specific (i dunno anything about its sensitivity) in my previous post.

 

[wwspeeds]

Myoglobin increases the most quickly. It's non-specific, though. these are my notes: (they may not be completely accurate)

CK: use for dx of re-infarction; !!!
- elevated as early as 3 hours
- peaks within 18 to 24 hours;
- Sudden increases in CKMB (CK) represent new infarction rather than a delayed effect

Myoglobin: first "enzyme" elevated [not really an enzyme -ed]; often within 1-2 hours ; peaks @ 6-7 hours; lasts no more than 1 day; notoriously nonspecific

Tn: increase in 3-12 hours
- peak in 1 day
- gradually taper over next 10 days

 

[wwspeeds]

Barone is a hack -- He steals Goljan's jokes -- straight up intellectual theft.

i heard it with my own eyes