werner@aecom.UUCP (Craig Werner) (12/11/85)
The following annotated answers may be self-explantory, but are probably
more worthwhile with the Case History and questions printed out in front of you.
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Answers:
Q1: The symptoms described are Classical for Angina. The sympathetic nervous
system output precipitated by the Times Crossword caused Coronary vessel
constriction (spasm) which would have been asymptomatic if the vessel had been
totally open. A heart attack would have persisted, as would an aortic
dissection. Atherosclerosis has no symptoms at rest. The answer is B.
Q2: It takes several hours for tissue death to occur, 2-3 for a
subendocardial (just the inside surface), 6-8 for a transmural. The symptoms
don't match necrosis of the AV node, which would probably be a fatal
arrythmia. The answer is C.
Q3: All except E could lead to a heart attack. The reason E can't is that
anything that broke off from the descending aorta would travel down to either
the Kidneys, the Abdominal Viscera, or the legs, where is still would cause
serious harm but not a heart attack. Answer is therefore E.
Q4: All the tissue death is done within the first 6-8 hours. While lifesaving
in this frame, after that window all reperfusion does is convert an ischemic
(pale) infarct to a hemorrhagic (bloody) infarct. It might save tissue on the
margins, and several islands of cells in the infarcted area, but these could
heal to become foci for life-threatening arrythmias, so it's a judgement call.
Anyway, since it is > 6 hrs and reperfused, the odds are we are dealing with a
transmural (from the inside all the way to the outside) hemorrhagic anterior
wall infarction (since the Left Anterior Descending Coronary was the one that
wa blocked, and it supplies the anterior wall). Also, after 24 hours, all
this would be visible, so this rules out E. The answer is A.
Q5: Fibrinous Pericarditis (the immune's system response to all this dead
tissue) only occurs in Transmural infarcts, since it has to effect the outside
surface of the heart, ruling out A. The time course is wrong for B and C. The
symptoms are wrong for D. However, E is just right.
Q6: This is tricky. One could argue for B (acute reocclusion) since most of
the tissue is already dead. Most is not all, and moreover, the stress of the
new occlusion could cause spasm ala question 1 which would do the heart in.
Choice A (Pulmonary embolism) seems wrong for the same reason that Aortic
emboli was wrong in Question 3 - the current is going the wrong way, a thrombi
in the left heart would embolize to the body, not to the lungs. However, this
forgets that Pulmonary emboli can arise in all immobilized patients
originating in the legs, through the right heart to the lung. D (Fibrinous
pericarditis) is already occuring. E (fibrillation) is the most common cause
of sudden death post heart attack. That leaves C. And the truth is,
Tamponade would not come on that suddenly. So the choice is wrong. The answer
is C.
Q7: In a coronary infarction, the lining of the heart is damaged and hence
accumulations of platelets, cells, etc, are not prevented from forming. This
is made worse by the stasis in the ventricle caused by the death of the muscle
underlying the injury. Thus, even without considering the other
possibilities, the answer is A.
Q8: It's been a week, or so. Scar tissue starts forming after a day or two,
and heals to fibrous tissue after about 3 weeks. If the patient had lived a
month, C would be right. If he had lived 6 months, C and E would be right. If
he had died immediately, A would be right. If the patient had gone to the
Hospital immediately and been treated correctly, D would be right. As it is,
we have dying heart muscle (myocardial necrosis) and a forming scar
(granulation tissue). The answer is B.
--
Craig Werner
!philabs!aecom!werner
"Time flies when you're streaking out N. gonorrheae." rwh@aesat.UUCP (Russ Herman) (12/13/85)
> From: werner@aecom.UUCP (Craig Werner) > If the patient had gone to the > Hospital immediately and been treated correctly, D would be right. Come on, Craig. Two questions we're "dying" to have answered: 1. What would have been "treated correctly"? How would it have improved his probability of survival? 2. What are the grounds for his survivors' malpractice suit :-) -- Russ Herman {allegra,ihnp4,linus,decvax}!utzoo!aesat!rwh