equinoxe
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please help with this one:
A 61-year-old man presents to the emergency room with crushing substernal chest pain. The pain began 20 minutes ago. A 12-lead electrocardiogram (ECG) is recorded, and based on results, the patient undergoes emergent coronary angiography and tissue plasminogen activator (TPA) infusion. The initial findings and subsequent result of TPA therapy are shown in the angiographic images (see figures). Based on the clinical presentation and these images, which of the following was most likely present on the patient’s initial ECG tracing?
A. Broad notched R waves with ST depression in leads I, AVL, and V6, and broad QS waves in V1-V3
B. Raised ST segment and Q waves in the Inferior leads (II, III and AVF)
C. S wave in lead I, a Q wave in lead III and an inverted T wave in lead III only
D. ST segment depression and T wave inversion with no Q waves
E. ST segment elevation in leads I, AVL, and V2-V6
Attached Files:
Jxf083f1.jpg (46 KB, 60 downloads)
Edited by equinoxe on 02/07/08 - 06:30 AM
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| arlete
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RCA obstruction = inferior MI = B
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| equinoxe
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thank you, yes, this is what the authors marked as well - but is there a thing as an acute q wave?
doesn't q wave take time to develop? after all this an acute condition and the initial ecg traicing should not have a q wave... so I thought and this is why I avoided this answer and landed on a wrong ans.
Edited by equinoxe on 02/07/08 - 08:11 AM
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| arlete
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Yes, Q waves take time to appear. They mean cicatricial tissue has been formed, where electricity does not run through.
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| arlete
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C is pulmonary embolism.
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| RX 135
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e ..lateral..LAD or circumflex
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| RX 135
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A ..POSTERIOR
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| RX 135
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D..ISCHEMIA
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| arlete
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Now I read the explanation and understood A is LBBB, not posterior MI...
Posterior MI changes would be ST depressions in V1 and V2, most likelly in addition of an inferior MI.
Edited by arlete on 02/07/08 - 03:02 PM
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| nyimalay
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My answer is E.
Does anyone know the correct answer??
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| DrVirgo
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Good question -Can anyone please explain what EXACTLY we are seeing in the angio pictures? Thanks.
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| equinoxe
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the answer the authors (step123) give as correct is B. But since they ask for "the patient’s initial ECG tracing" and there's no Hx of other chest pain/MI than this 20min ago episode - I would not chose any answer with a Q wave for sure. About the angio I also had hesitations, but I chose in the end ischemia D - wrong answer. Still Q waves after 20 min of ischemia... maybe prev hx of mi...
Option B (Raised ST segment and Q waves in the Inferior leads (II, III and AVF)) is correct. Complete occlusion of the right coronary artery would most likely show ECG tracings consistent with an inferior myocardial infarction.
Option A (Broad notched R waves with ST depression in leads I, AVL, and V6, and broad QS waves in V1-V3) is incorrect. These are ECG findings consistent with left bundle branch block. A complete right coronary artery occlusion most likely will show raised ST segment and Q waves in the inferior leads (II, III, and AVF).
Option C (S wave in lead I, a Q wave in lead III and an inverted T wave in lead III only) is incorrect. These are the ECG findings expected for an acute pulmonary embolism. A complete right coronary artery occlusion most likely will show raised ST segment and Q waves in the inferior leads (II, III, and AVF).
Option D (ST segment depression and T wave inversion with no Q waves) is incorrect. After 20 minutes of complete right coronary artery occlusion, ECG tracings will almost certainly show raised ST segment and Q waves in the inferior leads (II, III, and AVF).
Option E (ST segment elevation in leads I, AVL, and V2-V6) is incorrect. This pattern would indicate an anterolateral infarct. The angiogram shows a complete occlusion of the right coronary artery. ECG tracings would most likely show changes consistent with a right or inferior infarct.
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| nyimalay
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Thanks.
I think I need to interpret angiogram correctly before choosing answer.
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| farnsworth
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B is the right answer (inferior MI w/ ST-segment elevations in II, III, aVF), due to RCA obstruction/narrowing!
this is best seen on the right picture in LAO projection
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