Dora, a 58 year old female, presents to the ER with severe crushing chest pain. The pain began 1 hour earlier while she was tending to her garden. She also complains of left arm and jaw numbness. At rest, shortness of breath is apparent. She has a medical history of diabetes for 10 years and high cholesterol for 5 years. She is currently taking glucophage and lipitor daily for these conditions. Her family history reveals that her dad died of an MI at the age of 69.
B/P 160/98
RR 30
HR 110
O2% 91
Sinus Tachycardia
Pt is quickly placed on oxygen and given an aspirin. Morphine is given for chest pain and anxiety relief and a nitroglycerin drip is started for chest pain control. Labs are drawn. EKG reveals ST-segment elevation and large Q waves in leads II, III, and AVF. Reciprocal changes are seen in leads I and AVL. Cardiology is immediately called in to see her.
Chest pain is persistent even with Morphine and Nitroglycerin drip titration. Catheterization lab employees are called in for an emergency cardiac catheterization. Dora is admitted and diagnosed with an acute myocardial infarction.
1. Based on Dora's EKG changes what type of MI is she having?
a. lateral
b. anterior
c. septal
d. inferior
An EKG with ST-segment elevation in leads II, III, and AVF represents an inferior MI. These leads view the inferior surface of the left ventricle.
2. Q waves are noted on the EKG. What are Q-waves and what are the pathological differences between a non Q-wave MI and a Q-wave MI?
Presentation of a Q-wave on an EKG represents a necrotic muscle that longer produces electrical activity. Q-waves are usually persistent findings and do not go away over time. Q-wave MIs tend to be larger than non Q-wave MIs. They are also associated with a more prolonged and complete thrombosis. Q-waves can appear on an EKG within hours of an MI or may appear days after the onset of symptoms.
3. Lab tests come back and confirm that her cardiac enzymes are elevated but her troponin levels are normal. Explain the possible rationalization behind her normal troponin levels in presenting with an acute MI.
Increased serum enzymes, such as myoglobin, rise 2-4 hours after an MI and peak in 9-12 hours. Duration is usually 1-2 days. CK-MB levels are more specific cardiac markers that rise 3-6 hours after an MI and peak 12-24 hours. Duration is usually 1-3 days. Troponin levels are highly specific in cardiac death and usually rise 4-8 hours after an MI and peak 12-16 hours. Duration lasts the longest at 2 weeks. Because Dora was taken to the ER immediately after her symptoms of an MI you may not see a rise in Troponin just yet, but can expect to see it on her next lab draw.
4. What is a possible side affect of cardiac catheterization with PTCA when it is not followed by anticoagulation?
a. stroke
b. pneumonia
c. cardiac tamponade
d. re-stenosis
The crushed plaque against the arterial wall can lead to a thrombosis post stent insertion. If an anti-coagulant is not begun after PTCA, re-stenosis is a major risk of concern.
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