DrVirgo
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A subendocardial infarct will present with which of the following:
(pick all that apply)
ST Elevation
ST Depression
Q Waves
+ Cardiac Enzymes
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| arlete
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ST depression + cardiac enzymes
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| mildus
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ST depression, and cardiac enzymes (if it is not too small infarct). ST elevation and Q are in transmural infarct. What do you say?
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| DrVirgo
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I agree with ST depression and positive enzymes.
Are Q Waves ONLY found in Transmural Infarcts or can they be found in SOME Subendocardial Infarcts also?
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| mildus
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I think (although I can't guarantee) there is no Q in subendcardial infarction; however, even some transmural infarcts (if they are very small) can be without Q (it is also non-Q infarct)
Edited by mildus on 01/09/08 - 02:57 PM
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| arlete
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Sub epicardial and transmural infarcts have Q waves (not always, but most of the times). We know, "always" is a dangerous word in Medicine... No Q in subendocardial.
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| mildus
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Oh that "always", never know
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| DrVirgo
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You all are awesome... I know I learned this earlier, and I even posted it before but I got it mixed up again... so here is my final summary... Please let me know if its right.
Transmural Ischemia -ST elev, NO Q waves, No elevation in enzymes
Subendocardial Ischemia -ST Depr, NO Q waves, NO elevation in enzymes
Transmural Infarct -STelev, Q waves, and Enzymes elev.
Subendocardial Infarct -ST depr, NO Q waves, and Enzymes elev.
As I remember - ST elev means transmural and ST depr means Subendocardial paho.
Q waves only seen POST MI.
But 30-50% of MIs don't have Q-waves (Non Q-wave MI aka Subendocardial MI?)
Enzymes elev in MI -not Angina.
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| arlete
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I don't agree completely, I think it goes like this:
Subepicardial / Transmural ischemia = inverted T waves
Subendocardial ischemia = peaked positive T waves
The ischemia is not associated with ST segment changes, only T wave changes. When you have injury (infarct, enzymes elevation), then you have ST changes - exactly the ones you listed.
Edited by arlete on 01/09/08 - 04:57 PM
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| DrVirgo
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arlete wrote:
The ischemia is not associated with ST segment changes, only T wave changes. When you have injury (infarct, enzymes elevation), then you have ST changes - exactly the ones you listed.
Thanks for your help arlete. 
About what you said above....
In Prinzmetal's angina, there is ST Elevation.
And in Stable angina there is ST Depression.
Neither of these have infarct... Prinzmetal has cor.a spasm and angina can have some ischemia. But they BOTH have ST changes WITHOUT having infarct.
Right?
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| mildus
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apart from T wave changes, ST changes can be also present in ishaemia (usually depression, less frequent elevation, in that sence like you mentioned) but enzymes are normal;
infarcts without Q waves are subendocardial infarcts and some small transmural infarcts, majority of transmural infarcts has Q wave which is an indicator of necrosis and scar and appears after ST segment elevates
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| mildus
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DrVirgo your summary is very nice
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| cool doctor
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Transmural Ischemia -ST elev, NO Q waves, No elevation in enzymes
I dont think an ischemia will be associated with ST elevation.
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| DrVirgo
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cool doctor wrote:
Transmural Ischemia -ST elev, NO Q waves, No elevation in enzymes
I dont think an ischemia will be associated with ST elevation.
Ok, now I looked it up..
According to Kaplan:
Prinzmetal Variant Angina: "Transmural ischemia with ST segment elevation on EKG when symptomatic"
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| mildus
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A 12-lead ECG recorded at rest is normal in about half the patients with typical angina pectoris…
Typical ST-segment and T-wave changes that accompany episodes of angina pectoris and disappear thereafter are more specific.
In Unstable Angina, ST-segment depression, transient ST-segment elevation, and/or T-wave inversion occur in 30 to 50% of patients, depending on the severity of the clinical presentation.
The clinical diagnosis of variant angina is made with the detection of transient ST-segment elevation with rest pain.
Many patients also exhibit multiple episodes of asymptomatic ST-segment elevation (silent ischemia).
During the initial stage of the acute phase of MI, total occlusion of an epicardial artery produces ST-segment elevation. Most patients initially presenting with ST-segment elevation evolve Q waves on the ECG and are ultimately diagnosed as having sustained a Q-wave MI. A small proportion may sustain only a non-Q-wave MI.
Among patients presenting without ST-segment elevation, if a serum cardiac biomarker of necrosis is detected and no Q wave develops, the diagnosis of non-Q-wave MI is ultimately made. A minority of patients who present initially without ST-segment elevation may develop a Q-wave MI.
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| mildus
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Acute coronary syndromes. Following disruption of a vulnerable plaque, patients experience ischemic discomfort resulting from a reduction of flow through the affected epicardial coronary artery. The flow reduction may be caused by a completely occlusive thrombus or subtotally occlusive thrombus. Patients with ischemic discomfort may present with or without ST-segment elevation. Of patients with ST-segment elevation, the majority ultimately develop a Q-wave MI (QwMI), while a minority develop a non-Q-wave MI (NQMI). Patients who present without ST-segment elevation are suffering from either unstable angina or a non-ST-segment elevation MI (NSTEMI), a distinction that is ultimately made on the presence or absence of a serum cardiac marker such as CKMB or a cardiac troponin detected in the blood. The majority presenting with NSTEMI ultimately develop a NQMI on the ECG; a minority develop a QwMI. (Adapted from CW Hamm et al: Lancet 358:1533, 2001, and MJ Davies: Heart 83:361, 2000.)
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| mildus
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Both posts are copied from Harrison's Principles of Internal Medicine,16th Edition
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| arlete
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Yes, guys, you are right. Ischemia may produce ST elevation/depression. After all, that's what happens during the treadmill test, and the patient is not having an infarction (hopefully!)... That's what we see on silent ischemia during the holter, too...
Thank you...
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| cool doctor
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Thank you
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