Case Study: Evaluating and Managing a Patient with STEMI

Examining ST Segment Elevation and Heart Damage Location

Task:

You are in the middle of your shift in the coronary care unit (CCU) of a large urban medical center. Your new admission, C.B., a 47-year-old woman, was just flown to your institution from a small rural community more than 100 miles away. She had a STEMI (ST segment elevation myocardial infarction) last evening. Her current vital signs (VS) are 100/60, 86, 14. After you make C.B. comfortable, you receive this report from the flight nurse: “C.B. is a full-time homemaker with four children. She has had episodes of 'chest tightness' with exertion for the past year, but this is her first known MI. She has a history of hyperlipidemia and has smoked one pack of cigarettes daily for 30 years. Surgical history consists of total abdominal hysterectomy 10 years ago after the birth of her last child. She has no other known medical problems. Yesterday at 8 pm, she began to have severe substernal chest pain that referred into her neck and down both arms. She rated the pain as 9 or 10 on a 0-to-10 scale. She thought it was severe indigestion and began taking Maalox with no relief. Her husband then took her to the local emergency department, where a 12-lead electrocardiogram (ECG) showed hyperacute ST elevation in the inferior leads II, III, aVF and V5 to V6 . Before tissue plasminogen activator could be given, she went into ventricular fibrillation (V-fib). CPR was started and when the code team arrived, she was successfully defibrillated after two shocks. She then was started on nitroglycerin (NTG), heparin, and amiodarone drips. She was given IV metoprolol and aspirin 325mg to chew and swallow. This morning her systolic pressure dropped into the 80s, and she was placed on a low-dose norepinephrine drip and urgently flown to your institution for coronary angiography and possible percutaneous transluminal coronary angioplasty. Currently, she has amiodarone infusing at 1mg/min, heparin at 1200 units/hr, and norepinephrine at 0.5 mcg/kg/min. The NTG has been stopped because of low blood pressure. Laboratory work that was done yesterday showed Na 145mEq/L, K 3.6mEq/L, HCO3 19mEq/L, BUN 9mg/dL, creatinine 0.8mg/dL, WBC 14,500/mm3, Hct 44.3%, and Hgb 14.5g/dL.”

Questions:

1.Because the 12-lead ECG can tell you the location of the infarction, evaluate the leads that showed ST elevation. What areas of C.B.'s heart have been damaged?
2.Given the diagnosis of acute myocardial infarction (MI), what other laboratory results are you going to look at?
3.Indicate the expected outcome for C.B. associated with each medication she is receiving. For each of the drugs listed, state the purpose.
a. Intravenous (IV) nitroglycerin (NTG)
b. IV heparin
c. IV amiodarone
d. IV metoprolol
e. Aspirin, chewed and swallowed
f. IV norepinephrine
4.  You review the lab work on her chart. For each laboratory value listed previously, interpret the result, and evaluate the meaning for C.B.
5.  List at least two complications C.B. is at risk for at this time and the assessments that are
needed to identify these risks.
6.  You note that C.B.'s Spo2 on oxygen (O2) at 6L/min by nasal cannula is 92%. How do you
interpret this result?
7.  What can be done to promote her oxygenation at this time?
8.  An hour after her admission, you are preparing C.B. for her coronary intervention. Evaluate her readiness for teaching and her learning needs. What would you tell her?
Case Study Progress: The following day, you care for C.B. again. She is now on oral metoprolol, amiodarone, aspirin, and clopidogrel (Plavix). The norepinephrine and heparin have been discontinued. VS are stable:
9.  Which laboratory test result should you check before beginning the clopidogrel therapy?
a. PT/INR
b. aPTT
c. Platelet count
d. Potassium

Case Study Progress: As you work with C.B., you notice that she is extremely anxious. You had observed some anxiety yesterday, which you had attributed to the strange CCU environment, pain, and anticipation of the stenting procedure. The postprocedure test results showed that the stent was performing appropriately. You wonder what is wrong. She tells you that her heart attack occurred right in the middle of a move with her family from her rural community to an even smaller and unfamiliar town some 500 miles away in a neighboring state. She is dreading the move. Her husband “becomes angry easily and starts lashing out” toward her and the children. She is afraid to move to a community where she will have no friends and family to support her:

10.  How can you help your patient? Evaluate the situation and describe possible interventions.